Early prosthetic joint infections treated with debridement and implant retention: 38 primary hip arthroplasties prospectively recorded and followed for median 4 years

Background and purpose

Debridement and retention of the prosthesis is often attempted to treat early prosthetic joint infection (PJI). However, previous studies have found inconsistent results, with success rates ranging from 21% to 100%, and little has been written in the literature about hip function. We have therefore analyzed the clinical and functional outcome of early PJIs treated with this procedure.

Patients and methods

38 patients with early PJI after primary hip arthroplasty who were treated with debridement and retention of the implant between 1998 and 2005 were studied prospectively, with a median follow-up time of 4 (0.8–10) years. Early infection was defined as that which occurred within 4 weeks of index arthroplasty. The primary outcome measure was infection control. Functional outcome was assessed with the Harris hip score.

Results

27 of 38 patients were successfully treated, with no signs of infection or continued antibiotic treatment at the latest follow-up. Median Harris hip score was 86 (47–100) points. In 9 of the 11 patients for whom treatment failed, infection was successfully treated with 1-stage or 2-stage reimplantation or resection. Intraoperative cultures were positive in 36 hips, and the most frequently isolated organisms were Staphylococcus aureus and coagulase-negative staphylococci (CoNS). 15 infections were polymicrobial, and only 8 of them were successfully treated with debridement and retention of the implant.

Interpretation

Our data suggest that debridement and retention of the prosthesis is a reasonable treatment option in early PJI after primary hip arthroplasty, with satisfactory functional results.Prosthetic joint infection (PJI) occurs with an incidence of around 1% after primary hip surgery (NIH consensus conference 1995, Gaine et al. 2000, Phillips et al. 2006). The number of patients requiring a joint replacement is steadily increasing, and the absolute number of PJIs will be rising (NIH consensus conference 1995). Recent publications even suggest that the incidence of infection is increasing (Kurtz et al. 2008, Dale et al. 2009).In early PJI, debridement with retention of the implant is an attractive treatment option. This procedure reduces morbidity, and also length of hospital stay and costs, compared to 1-stage or 2-stage revision arthroplasty (Fisman et al. 2001). The reported success rates of this procedure range from 21% to 100% (Drancourt et al. 1993, Tsukayama et al. 1996, Brandt et al. 1997, Crockarell et al. 1998, Zimmerli et al. 1998, Barberan et al. 2006, Choong et al. 2007, Van Kleunen et al. 2010). Different definitions of acute postoperative infection, with length varying from 4 weeks to 3 months, combined with heterogenous patient series, make comparison of these studies difficult.Here we evaluated the clinical outcome of early PJI treated with debridement and retention of the implant in an 8-year prospective cohort.     

Effects of metal-on-metal wear on the host immune system and infection in hip arthroplasty

Background and purpose

Joint replacement with metal-on-metal (MOM) bearings have gained popularity in the last decades in young and active patients. However, the possible effects of MOM wear debris and its corrosion products are still the subject of debate. Alongside the potential disadvantages such as toxicity, the influences of metal particles and metal ions on infection risk are unclear.

Methods

We reviewed the available literature on the influence of degradation products of MOM bearings in total hip arthroplasties on infection risk.

Results

Wear products were found to influence the risk of infection by hampering the immune system, by inhibiting or accelerating bacterial growth, and by a possible antibiotic resistance and heavy metal co-selection mechanism.

Interpretation

Whether or not the combined effects of MOM wear products make MOM bearings less or more prone to infection requires investigation in the near future.Many young patients with painful coxarthrosis want to return to a high level of activity and require an implant that provides durability. The low wear rates of metal-on-metal (MOM) bearings have led to a resurgence in the use of MOM bearings (Wagner and Wagner 2000, Silva et al. 2005, Pollard et al. 2006, Vendittoli et al. 2007, Delaunay et al. 2008). 35% of all prostheses in the United States in 2006 (Bozic et al. 2009) and 16% of all prostheses implanted in Australia from 1999 through 2007 had MOM bearings (Graves et al. 2008).Metal alloys used in MOM bearings degrade through wear, from corrosion, or by a combination of the two (Yan et al. 2006, Jacobs et al. 2008). Consequently, MOM bearings produce nanometer- to submicrometer-sized metal particles (Campbell et al. 1996, Doorn et al. 1998). The high number of these very small particles presents a large cumulative surface area for corrosion. The biological effects of these particles and their corrosion products in the human body are for the most part unclear. Since the renewed interest in MOM bearings, extensive research has been done to determine the consequences of local and systemic exposure to wear particles and accompanying biologically active corrosion products (Amstutz and Grigoris 1996). It is well known that metal debris can induce pathological changes such as the release of inflammatory cytokines from macrophages, histiocytosis, fibrosis, and necrosis (Basle et al. 1996, Granchi et al. 1998, Caicedo et al. 2008, 2009). Metal debris is also thought to be associated with hypersensitivity and osteolysis (Hallab et al. 2000, 2010, Goodman 2007b, Carr and DeSteiger 2008, Huber et al. 2009). However, there is very little literature on the bacteriological effects of these degradation products (Anwar et al. 2007, Hosman et al. 2009). It is therefore unclear whether they can influence the risk of infection.The Australian and New Zealand joint registries have shown that between 9% and 15% of all total hip arthroplasty (THA) revisions are carried out because of infections related to the primary prosthesis (Rothwell et al. 2007, Graves et al. 2008). In cases of infection, bacteria adopt a biofilm mode of growth on the surface of the prosthesis, thus increasing the antibiotic resistance and resulting in major difficulties in treatment (Trampuz and Widmer 2006). Removal and replacement of an infected implant is usually required to eliminate the infection (Bozic and Ries 2005, Vincent et al. 2006). Recent research has suggested that particulate debris of any composition promotes bacterial growth by providing a scaffold for bacterial adhesion and biofilm growth (Anwar et al. 2007). On the other hand, high concentrations of metal ions have been shown to have bacteriostatic properties (Hosman et al. 2009).Considering the paucity of publications on the effects of MOM particles on infection, we performed a review of the literature on the influence of MOM wear particles and their corrosion products on the risk of infection.     

18F-FDG microPET imaging differentiates between septic and aseptic wound healing after orthopedic implant placement: A longitudinal study of an implant osteomyelitis in the rabbit tibia

Background and purpose

¹⁸F-FDG PET is a widely used tool for molecular imaging of oncological, cardiovascular, and neurological disorders. We evaluated ¹⁸F-FDG microPET as an implant osteomyelitis imaging tool using a Staphylococcus aureus-induced peroperative implant infection in rabbits.

Methods

Intramedullary titanium nails were implanted in contaminated and uncontaminated (control) proximal right tibiae of rabbits. Tibiae were quantitatively assessed with microPET for ¹⁸F-FDG uptake before and sequentially at 1, 3, and 6 weeks after surgery. Tracer uptake was assessed in soft tissue and bone in both treatment groups with an additional comparison between the operated and unoperated limb. MicroPET analysis was combined with radiographic assessment and complementary histology of the tibiae.

Results

At the first postoperative week, the ¹⁸F-FDG uptake in the contaminated implant group was significantly higher than the preoperative measurement, without a significant difference between the contaminated and uncontaminated tibiae. From the third postoperative week onward, ¹⁸F-FDG uptake allowed discrimination between osteomyelitis and postoperative aseptic bone healing, as well as quantification of the infection at distinct locations around the implant.

Interpretation

¹⁸F-FDG-based microPET imaging allows differentiation between deep infection and undisturbed wound healing after implantation of a titanium intramedullary nail in this rabbit model. Furthermore, our results indicate that ¹⁸F-FDG PET may provide a tool in human clinical diagnostics and for the evaluation of antimicrobial strategies in animal models of orthopedic implant infection.With more prostheses and osteosyntheses being implanted every year and a suggested increase in infection rate, the absolute number of implant infections will increase (Dale et al. 2009, Acklin et al. 2011, Kurtz et al. 2012). Deep orthopedic implant infections are difficult to diagnose in the early postoperative weeks, while diagnosis of infection in this period is important for optimal treatment and implant survival. A specific diagnostic tool to monitor implant infections is therefore imperative.Current diagnostics to detect orthopedic implant infections are based on clinical symptoms, hematological parameters, radiology, and nuclear scintigraphy. However, as in low-grade infections, in the early postoperative phase changes such as periosteal reactions and cortical thickening (Calhoun and Mader 1997, Smeltzer et al. 1997, Odekerken et al. 2013) or osteolysis and calcifications (Calhoun and Mader 1997, Smeltzer et al. 1997, Vogely et al. 2000, Odekerken et al. 2013) are not specific enough to differentiate between implant/soft tissue infection and aseptic wound problems. More discriminative power is needed to distinguish aseptic wound healing from bacterial infection and to follow implant infection quantitatively over time. ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) is widely used as a positron emission tomography (PET) tracer to diagnose and monitor several pathological conditions in the clinic (Stumpe et al. 2000, Toyama et al. 2004a,b, van der Bruggen et al. 2010, Huang et al. 2012, Marsboom et al. 2012). The use of ¹⁸F-FDG as a tracer is based on a local increase in metabolic turnover of glucose. Since the presence of bacteria and increased leukocyte infiltration in an infected area generates such a local increase in glucose turnover and leads to increased ¹⁸F-FDG uptake (Stumpe et al. 2000, Koort et al. 2004, Makinen et al. 2005a), local detection of bacterial infections is possible.We hypothesized that ¹⁸F-FDG PET scanning would be capable of providing the discriminative power needed to distinguish aseptic wound healing from orthopedic implant infection. To test this hypothesis, we sequentially determined the development of implant osteomyelitis by ¹⁸F-FDG microPET scanning of contaminated and uncontaminated rabbit tibiae and explored its possible use in diagnosis of implant infection.     

Perioperative mortality after hemiarthroplasty related to fixation method

Background and purpose

The appropriate fixation method for hemiarthroplasty of the hip as it relates to implant survivorship and patient mortality is a matter of ongoing debate. We examined the influence of fixation method on revision rate and mortality.

Methods

We analyzed approximately 25,000 hemiarthroplasty cases from the AOA National Joint Replacement Registry. Deaths at 1 day, 1 week, 1 month, and 1 year were compared for all patients and among subgroups based on implant type.

Results

Patients treated with cemented monoblock hemiarthroplasty had a 1.7-times higher day-1 mortality compared to uncemented monoblock components (p < 0.001). This finding was reversed by 1 week, 1 month, and 1 year after surgery (p < 0.001). Modular hemiarthroplasties did not reveal a difference in mortality between fixation methods at any time point.

Interpretation

This study shows lower (or similar) overall mortality with cemented hemiarthroplasty of the hip.The frequency of hip fractures is increasing with our ageing population, with an annual incidence of between 1.4 and 5 per 103 per year (Lonnroos et al. 2006, Icks et al. 2008, Varez-Nebreda et al. 2008). Health model projections have estimated that 6.3 million hip fractures will occur annually worldwide within the next 40 years (Cooper et al. 1992), imposing a significant economic health burden. There is a large reported perioperative mortality rate in this population, ranging from 2.4% to 8.2% at 1 month (Parvizi et al. 2001, Radcliff et al. 2008) and over 25% at 1 year (Elliott et al. 2003, Jiang et al. 2005). Furthermore, it was recently reported that the current mortality rate is higher now than 25 years ago (Vestergaard et al. 2007a). Today, it is generally accepted that displaced intracapsular fractures are best treated with arthroplasty rather than internal fixation (Keating et al. 2006, Leighton et al. 2007). In the at-risk population, however, multiple comorbidities are common and the best form of component fixation is in question.Bone cement implantation syndrome is a well-described complication of cemented hip arthroplasty. It is characterized by a systemic drop in systolic blood pressure, hypoxemia, pulmonary hypertension, cardiac dysrhythmias, and occasionally cardiac arrest and death (Rinecker 1980, Orsini et al. 1987, Parvizi et al. 1999). The prevailing theory to explain the pathophysiology of this phenomenon is embolism of fat, marrow contents, bone, and to some degree methylmethacrylate to the lung (Rinecker 1980, Elmaraghy et al. 1998, Parvizi et al. 1999, Koessler et al. 2001). An increased degree of pulmonary insult with fat microemboli has been demonstrated (mostly in randomized controlled trials) during insertion of a cemented femoral stem rather than an uncemented implant (Orsini et al. 1987, Ries et al. 1993, Christie et al. 1994, Pitto et al. 1999), presumably due to increased intramedullary femoral canal pressures in the cemented group (Kallos et al. 1974, Orsini et al. 1987). These pressures can be reduced by the use of distal venting holes in the femur during stem insertion (Engesæter et al. 1984). It has been shown previously by single-institutional review that patients undergoing cemented hip arthroplasty have a higher intraoperative mortality rate relative to uncemented arthroplasty, presumably due to a reduced incidence of fat embolism in the latter group (Parvizi et al. 1999). The increased mortality risk was also present at 30 days in the treatment of acute fractures with cemented arthroplasty, also from a single-institutional review (Parvizi et al. 2004). Although cement-related mortality is rare (Dearborn and Harris 1998, Parvizi et al. 1999, 2001, 2004, Weinrauch et al. 2006), it is a devastating complication—often reported through observational studies or literature reviews. Proponents of uncemented hip arthroplasty often cite this concern to support their reluctance to use cemented hip arthroplasty in both elective procedures and fracture management. However, many different types of studies have been unable to identify any increased mortality risk with the use of cement (Lausten and Vedel 1982 (observational), Emery et al. 1991 (RCT), Lo et al. 1994 (observational), Khan et al. 2002a,b (literature review), Parker and Gurusamy 2004 (literature review)) and others have shown a decrease in mortality at 30 days when cement is used (Foster et al. 2005).Cemented hip hemiarthroplasty appears to offer improved rate of return to baseline function, reduced postoperative pain, and superior long-term survivorship relative to uncemented arthroplasty (Khan et al. 2002a, b, Parker and Gurusamy 2004). We reasoned that failure to return to baseline function after hemiarthroplasty may be another risk factor for perioperative mortality (Hannan et al. 2001, Braithwaite et al. 2003). Lower revision rates for cemented prostheses and increased mortality at revision surgery contribute further to reducing the overall mortality risk. We evaluated the relationship between the method of fixation of hip arthroplasty and perioperative mortality using a large national joint replacement registry.     

PCR-hybridization after sonication improves diagnosis of implant-related infection

Purpose

We wanted to improve the diagnosis of implant-related infection using molecular biological techniques after sonication.

Methods

We studied 258 retrieved implant components (185 prosthetic implants and 73 osteosynthesis implants) from 126 patients. 47 patients had a clinical diagnosis of infection (108 components) and 79 patients did not (150 components). The fluids from sonication of retrieved implants were tested in culture and were also analyzed using a modified commercial PCR kit for detection of Gram-positive and Gram-negative bacteria (GenoType BC; Hain Lifescience) after extraction of the DNA.

Results

38 of 47 patients with a clinical diagnosis of infection were also diagnosed as being infected using culture and/or PCR (35 by culture alone). Also, 24 patients of the 79 cases with no clinical diagnosis of infection were identified microbiologically as being infected (4 by culture, 16 by PCR, and 4 by both culture and PCR). Comparing culture and PCR, positive culture results were obtained in 28 of the 79 patients and positive PCR results were obtained in 35. There were 21 discordant results in patients who were originally clinically diagnosed as being infected and 28 discordant results in patients who had no clinical diagnosis of infection.

Interpretation

For prosthetic joint infections and relative to culture, molecular detection can increase (by one tenth) the number of patients diagnosed as having an infection. Positive results from patients who have no clinical diagnosis of infection must be interpreted carefully.Management of orthopedic implant-related infections starts with a proper etiological diagnosis, which is required for specific antibiotic treatment. Different approaches are used to obtain such a diagnosis (Trampuz et al. 2006, Del Pozo and Patel 2009) and these must take into account the importance of the development of bacterial biofilms in the pathogenesis and management of implant-related infections (Trampuz et al. 2003, 2006, Costerton 2005).The use of low-intensity ultrasound that releases biofilms is an alternative to classical culture methods from implants, and several protocols have been developed for this purpose (Trampuz et al. 2007, Dora et al. 2008, Esteban et al. 2008, Piper et al. 2009, Achermann et al. 2010). In these reports, the use of sonication of retrieved implants was reported to have similar sensitivity to or higher sensitivity than conventional techniques. Nevertheless, there are still patients with a clinical diagnosis of infection and negative cultures (Berbari et al. 2007). Previous use of antibiotics has been implicated as one of the main causes of this problem (Trampuz et al. 2007), but other causes are also possible. To solve the problem, molecular biological techniques have been proposed in order to obtain faster and more accurate results than conventional culture (Tunney et al. 1999, Sauer et al. 2005, Dempsey et al. 2007, Fihman et al. 2007, Moojen et al. 2007, Gallo et al. 2008, Kobayashi et al. 2008, Vandercam et al. 2008, De Man et al. 2009, Piper et al. 2009, Achermann et al. 2010, Riggio et al. 2010, Marin et al. 2012). Most of these reports were based on protocols that were developed in-house, which are difficult to integrate into clinical microbiology routines, even though they may give good results. Recently, however, commercial kits have been designed to work under common routine laboratory conditions. Here, we describe a study on the diagnosis of infection in a broad range of orthopedic implant-related infections, comparing conventional culture with detection of microbial DNA using a commercial kit—in both cases after sonication of retrieved implants.     

Metal-backed versus all-polyethylene tibial components in primary total knee arthroplasty

Background and purpose

The choice of either all-polyethylene (AP) tibial components or metal-backed (MB) tibial components in total knee arthroplasty (TKA) remains controversial. We therefore performed a meta-analysis and systematic review of randomized controlled trials that have evaluated MB and AP tibial components in primary TKA.

Methods

The search strategy included a computerized literature search (Medline, EMBASE, Scopus, and the Cochrane Central Register of Controlled Trials) and a manual search of major orthopedic journals. A meta-analysis and systematic review of randomized or quasi-randomized trials that compared the performance of tibial components in primary TKA was performed using a fixed or random effects model. We assessed the methodological quality of studies using Detsky quality scale.

Results

9 randomized controlled trials (RCTs) published between 2000 and 2009 met the inclusion quality standards for the systematic review. The mean standardized Detsky score was 14 (SD 3). We found that the frequency of radiolucent lines in the MB group was significantly higher than that in the AP group. There were no statistically significant differences between the MB and AP tibial components regarding component positioning, knee score, knee range of motion, quality of life, and postoperative complications.

Interpretation

Based on evidence obtained from this study, the AP tibial component was comparable with or better than the MB tibial component in TKA. However, high-quality RCTs are required to validate the results.The design of the tibial component is an important factor for implant failure in total knee arthroplasty (TKA) (Pagnano et al. 1999, Forster 2003, Gioe et al. 2007b, Willie et al. 2008, Garcia et al. 2009, KAT Trial Group 2009). The metal-backed (MB) design of tibial component has become predominant in TKA because it is thought to perform better than the all-polyethylene (AP) design (Muller et al. 2006, Gioe et al. 2006, 2007a,b). In theory, the MB tibial component reduces bending strains in the stem, reduces compressive stresses in the cement and cancellous bone beneath the baseplate (especially during asymmetric loading), and distributes load more evenly across the interface (Bartel et al. 1982, 1985, Taylor et al. 1998). However, critics of the MB tibial component claim that there are expensive implant costs, reduced polyethylene thickness with the same amount of bone resection, backside wear, and increased tensile stresses at the interface during eccentric loading (Bartel et al. 1982, 1985, Pomeroy et al. 2000, Rodriguez et al. 2001, Li et al. 2002, Muller et al. 2006, Blumenfeld and Scott 2010, Gioe and Maheshwari 2010).In the past decade, several randomized controlled trials (RCTs) have been performed to assess the effectiveness of the MB tibial component (Adalberth et al. 2000, 2001, Gioe and Bowman 2000, Norgren et al. 2004, Hyldahl et al. 2005a, b, Muller et al. 2006, Gioe et al. 2007, Bettinson et al. 2009, KAT Trial Group 2009). However, data have not been formally and systematically analyzed using quantitative methods in order to determine whether the MB tibial component is indeed optimal for patients in TKA. In this study, we wanted (1) to determine the scientific quality of published RCTs comparing the AP and MB tibial components in TKA using Detsky score (Detsky et al. 1992) and (2) to conduct a meta-analysis and systematic review of all published RCTs that have compared the effects of AP and MB tibial components on the radiographic and clinical outcomes of TKA.     

Risk factors for revision due to infection after primary total hip arthroplasty: A population-based study of 80,756 primary procedures in the Danish Hip Arthroplasty Registry

Background and purpose

There has been a limited amount of research on risk factors for revision due to infection following total hip arthroplasty (THA), probably due to low absolute numbers of revisions. We therefore studied patient- and surgery-related risk factors for revision due to infection after primary THA in a population-based setting.

Materials and methods

Using the Danish Hip Arthroplasty Registry, we identified 80,756 primary THAs performed in Denmark between Jan 1, 1995 and Dec 31, 2008. We used Cox regression analysis to compute crude and adjusted relative risk (RR) of revision due to infection. Revision was defined as extraction or exchange of any component due to infection. The median follow-up time was 5 (0–14) years.

Results

597 primary THAs (0.7%) were revised due to infection. Males, patients with any co-morbidity, patients operated due to non-traumatic avascular femoral head necrosis, and patients with long duration of surgery had an increased RR of revision due to infection within the total follow-up time. A tendency of increased RR of revision was found for patients who had received cemented THA without antibiotic and hybrid THA relative to patients with cementless implants. Hip diagnosis and fixation technique were not associated with risk of revision due to infection within 1 year of surgery (short-term risk).

Interpretation

We identified several categories of THA patients who had a higher risk of revision due to infection. Further research is required to explain the mechanism underlying this increased risk. More attention should be paid by clinicians to infection prevention strategies in patients with THA, particularly those with increased risk.As with any other surgical operation, serious complications in patients undergoing total hip arthroplasty (THA) include infections. Most infections stem either from contamination in the operating room or from later hematogenous spread. Deep infection is the third most common cause of revision of THAs in Denmark (DHR Annual repport 2008). In the last 2 decades, advances in theater design and the prophylactic use of antibiotics, either systemically or incorporated in cement, have substantially reduced the incidence of infection after hip replacement (Zimmerli and Ochsner 2003, Ridgeway et al. 2005, Phillips et al. 2006). However, recent studies in the United States and Norway have found increasing infection rates (Dale et al. 2009, Kurtz et al. 2010).Research on risk factors for revision due to infection following THA has been limited, probably due to low absolute numbers of revisions. However, in the last few years several reports have suggested that some patient- and surgery-related factors may play a role (Furnes et al. 2001, Saleh et al. 2002, Ridgeway et al. 2005, Engesaeter et al. 2006, Bongartz et al. 2008, Pulido et al. 2008, Dale et al. 2009, Hooper et al. 2009, Ong et al. 2009). Comparison of these studies is difficult due to different inclusion criteria for the study population and different definitions of infection, sometimes including both joint infections and superficial infections, or infections in general. We studied only the infections that were followed by revision of the implant.For this reason, we conducted a nationwide follow-up study using the Danish Hip Arthroplasty Registry to examine potential patient- and surgery-related risk factors for revision due to infection.     

Surgical procedures in the treatment of 784 infected THAs reported to the Norwegian Arthroplasty Register

Background and purpose

Controversies still exist regarding the best surgical procedure in the treatment of periprosthetic infection after total hip arthroplasty (THA). Based on data in the Norwegian Arthroplasty Register (NAR), we have compared the risk of re-revision after 4 different surgical procedures: 2-stage with exchange of the whole prosthesis, 1-stage with exchange of the whole prosthesis, major partial 1-stage with exchange of stem or cup, and minor partial 1-stage with exchange of femoral head and/or acetabular liner.

Methods

Between 1987 and 2009, 124,759 primary THAs were reported to the NAR, of which 906 (0.7%) were revised due to infection. Included in this study were the 784 revisions that had been performed by 1 of the 4 different surgical procedures. Cox-estimated survival and relative revision risks are presented with adjustment for differences among groups regarding gender, type of fixation, type of prosthesis, and age at revision.

Results

2-stage procedures were used in 283 revisions (36%), 1-stage in 192 revisions (25%), major partial in 129 revisions (17%), and minor partial in 180 revisions (23%). 2-year Kaplan-Meier survival for all revisions was 83%; it was 92% for those re-revised by 2-stage exchange procedure, 88% for those re-revised by 1-stage exchange procedure, 66% for those re-revised by major partial exchange procedure, and it was 76% for those re-revised by minor partial exchange. Compared to the 2-stage procedure and with any reason for revision as endpoint (180 re-revisions), the risk of re-revision increased 1.4 times for 1-stage (p = 0.2), 4.1 times for major partial exchange (p < 0.001), and 1.5 times for minor partial exchange (p = 0.1). With infection as the endpoint (108 re-revisions), the risk of re-revision increased 2.0 times for 1-stage exchange (p = 0.04), 6.0 times for major partial exchange (p < 0.001), and 2.3 times for minor partial exchange (p = 0.02). Similar results were found when the analyses were restricted to the period 2002–2009.

Interpretation

In the Norwegian Arthroplasty Register, the survival after revision of infected primary THA with 2-stage implant exchange was slightly superior to that for 1-stage exchange of the whole prosthesis. This result is noteworthy, since 2-stage procedures are often used with the most severe infections. However, debridement with exchange of head and/or liner but with retention of the fixed implant (minor revision) meant that there was a 76% chance of not being re-revised within 2 years.The risk of periprosthetic infection after total hip arthroplasty (THA) has decreased from 5–10% in the late 1960s to around 1% today (Lidgren 2001, Lidgren et al. 2003, Zimmerli and Ochsner 2003, Dale et al. 2009, Walenkamp 2009, Ong et al. 2009, Urquhart et al. 2010). In the last few years, however, some reports have indicated that there is an increasing incidence of revisions for infected THA (Kurtz et al. 2008, Dale et al. 2009, Pedersen et al. 2010).The optimum treatment of deep infection remains controversial (Toms et al. 2006). 2-stage exchange requires a minimum of 2 surgical procedures and a substantial period of reduced mobility. Removal of a well-fixed cemented prosthesis may also result in degradation of the bone stock and perioperative fracture (Langlais 2003, Ong et al. 2009, Bejon et al. 2010). A procedure with debridement, antibiotics, and implant retention (DAIR) with or without exchange of removable parts (i.e. liner and/or head), which is technically less demanding, could therefore be an attractive option for treatment of early deep infections, especially in elderly or frail patients (Giulieri et al. 2004, Trebse et al. 2005, Toms et al. 2006, Byren et al. 2009).In this paper, based on the data in the Norwegian Arthroplasty Register (NAR), we compared the risk of re-revision after the first surgical revision for deep infection of a primary THA by one of the following 4 surgical procedures: 2-stage exchange of the whole prosthesis, 1-stage exchange of the whole prosthesis, major partial 1-stage with exchange of stem or acetabulum, and minor partial 1-stage with exchange of acetabular liner and/or femoral head (Trampuz and Zimmerli 2006).     

Locking plate osteosynthesis in displaced 4-part fractures of the proximal humerus

Background and purpose

There is considerable uncertainty about the optimal treatment of displaced 4-part fractures of the proximal humerus. Within the last decade, locking plate technology has been considered a breakthrough in the treatment of these complex injuries.

Methods

We systematically identified and reviewed clinical studies on the benefits and harms after osteosynthesis with locking plates in displaced 4-part fractures.

Results

We included 14 studies with 374 four-part fractures. There were 10 case series, 3 retrospective observational comparative studies, 1 prospective observational comparative study, and no randomized trials. Small studies with a high risk of bias precluded reliable estimates of functional outcome. High rates of complications (16–64%) and reoperations (11–27%) were reported.

Interpretation

The empirical foundation for the value of locking plates in displaced 4-part fractures of the proximal humerus is weak. We emphasize the need for well-conducted randomized trials and observational studies.There is considerable uncertainty about the optimal treatment of displaced 4-part fractures of the proximal humerus (Misra et al. 2001, Handoll et al. 2003, Bhandari et al. 2004, Lanting et al. 2008). Only 2 small inconclusive randomized trials have been published (Stableforth 1984, Hoellen et al. 1997). A large number of interventions are used routinely, ranging from a non-operative approach to open reduction and internal fixation (ORIF), and primary hemiarthroplasty (HA).In the last decade, locking plate technology has been developed and has been heralded as a breakthrough in the treatment of fractures in osteoporotic bone (Gautier and Sommer 2003, Sommer et al. 2003, Haidukewych 2004, Miranda 2007). Locking plate technique is based on the elimination of friction between the plate and cortex, and relies on stability between the subchondral bone and screws. Multiple multidirectional convergent and divergent locking screws enhance the angular stability of the osteosynthesis, possibly resulting in better postoperative function with reduced pain. Reported complications include screw cut-out, varus fracture collapse, tuberosity re-displacement, humeral head necrosis, plate impingement, and plate or screw breakage (Hall et al. 2006, Tolat et al. 2006, van Rooyen et al. 2006, Agudelo et al. 2007, Gardner et al. 2007, Khunda et al. 2007, Ring 2007, Smith et al. 2007, Voigt et al. 2007, Egol et al. 2008, Kirchhoff et al. 2008, Owsley and Gorczyca 2008, Brunner et al. 2009, Micic et al. 2009, Sudkamp et al. 2009). The balance between the benefit and harms of the intervention seems delicate.Several authors of narrative reviews and clinical series have strongly recommended fixation of displaced 4-part fractures of the humerus with locking plates (Bjorkenheim et al. 2004, Hente et al. 2004, Hessler et al. 2006, Koukakis et al. 2006, Kilic et al. 2008, Korkmaz et al. 2008, Shahid et al. 2008, Papadopoulos et al. 2009, Ricchetti et al. 2009) and producers of implants unsurprisingly strongly advocate them (aap Implantate 2010, Stryker 2010, Synthes 2010, Zimmer 2010). Despite the increasing use of locking plates (Illert et al. 2008, Ricchetti et al. 2009), we have been unable to identify systematic reviews on the benefits and harms of this new technology in displaced 4-part fractures. Thus, we systematically identified and reviewed clinical studies on the benefits and harms after osteosynthesis with locking plates in displaced 4-part fractures of the proximal humerus.     

Hydroxyapatite coating does not improve uncemented stem survival after total hip arthroplasty!: An analysis of 116,069 THAs in the Nordic Arthroplasty Register Association (NARA) database

ResultsUnadjusted 10-year survival with the endpoint revision of any component for any reason was 92.1% (CI: 91.8–92.4). Unadjusted 10-year survival with the endpoint stem revision due to aseptic loosening varied between the stem brands investigated and ranged from 96.7% (CI: 94.4–99.0) to 99.9% (CI: 99.6–100). Of the stem brands with the best survival, stems with and without HA coating were found. The presence of HA coating was not associated with statistically significant effects on the adjusted risk of stem revision due to aseptic loosening, with an HR of 0.8 (CI: 0.5–1.3; p = 0.4). The adjusted risk of revision due to infection was similar in the groups of THAs using HA-coated and non-HA-coated stems, with an HR of 0.9 (CI: 0.8–1.1; p = 0.6) for the presence of HA coating. The commonly used Bimetric stem (n = 25,329) was available both with and without HA coating, and the adjusted risk of stem revision due to aseptic loosening was similar for the 2 variants, with an HR of 0.9 (CI: 0.5–1.4; p = 0.5) for the HA-coated Bimetric stem.InterpretationUncemented HA-coated stems had similar results to those of uncemented stems with porous coating or rough sand-blasted stems. The use of HA coating on stems available both with and without this surface treatment had no clinically relevant effect on their outcome, and we thus question whether HA coating adds any value to well-functioning stem designs.Hydroxyapatite (HA) is thought to improve early implant ingrowth and long-term stability in bone (Overgaard et al. 1997), and many stems intended for uncemented total hip arthroplasty (THA) are thus manufactured with HA coating. Several uncemented stems are only available with HA coating. Some HA-coated stems have excellent long-term outcomes in terms of the risk of revision, both for any reason and due to aseptic loosening (Capello et al. 2003, Shah et al. 2009). Registry data from Norway and Finland also indicate that certain HA-coated stems have excellent survivorship up to 10 years (Eskelinen et al. 2006, Hallan et al. 2007, Makela et al. 2008).On the other hand, a number of studies on stem survival in the setting of randomized trials or smaller observational studies have failed to show beneficial effects of HA coating on clinical outcome and implant survival when compared to alternatives such as porous coating and sand-blasted rough surfaces (McPherson et al. 1995, Tanzer et al. 2001, Kim et al. 2003, Parvizi et al. 2004, Sanchez-Sotelo et al. 2004). Meta-analyses that have pooled data from randomized or cohort studies have come to the conclusion that there is “[…] no clinically beneficial effect to the addition of HA to porous coating alone in primary uncemented hip arthroplasty” (Gandhi et al. 2009, Li et al. 2013). In addition, a Danish registry analysis found that the use of HA coating does not reduce the risk of stem revision (Paulsen et al. 2007). Furthermore, a comparison of 4,772 uncemented Bimetric stems with or without HA coating implanted between 1992 and 2009 did not reveal any difference in survival between the 2 variants (Lazarinis et al. 2011).HA was initially introduced as an implant coating to speed up and facilitate ongrowth and ingrowth of bone and thereby improve fixation, based on comprehensive preclinical and promising clinical documentation (Geesink et al. 1987, Bauer et al. 1991, Overgaard et al. 1997, Karrholm et al. 1998). Later on, concerns were raised due to findings of delamination and generation of HA particles originating from the coating with the potential to trigger osteolysis, acceleration of polyethylene wear, and subsequent implant loosening (Bloebaum and Dupont 1993, Morscher et al. 1998, Lazarinis et al. 2010). Today, there is renewed interest in HA coatings due to possible properties as a carrier for agents aimed at preventing infection (Ghani et al. 2012). Theoretical arguments for and against the use of HA coating can therefore be found. Given the renewed interest in uncemented stems—instigated by favorable outcomes after uncemented stem fixation in younger patients—the question of whether HA coating is beneficial or not is highly relevant (Eskelinen et al. 2006, Hooper et al. 2009, Swedish Hip Arthroplasty Register 2011). We therefore investigated uncemented stems with and without HA coating that are in frequent use in the Nordic countries, regarding early and long-term survival.     

75% success rate after open debridement,exchange of tibial insert,and antibiotics in knee prosthetic joint infections: Report on 145 cases from the Swedish Knee Arthroplasty Register

Background and purpose

Prosthetic joint infection (PJI) is a leading cause of early revision after total knee arthroplasty (TKA). Open debridement with exchange of tibial insert allows treatment of infection with retention of fixed components. We investigated the success rate of this procedure in the treatment of knee PJIs in a nationwide material, and determined whether the results were affected by microbiology, antibiotic treatment, or timing of debridement.

Patients and methods

145 primary TKAs revised for the first time, due to infection, with debridement and exchange of the tibial insert were identified in the Swedish Knee Arthroplasty Register (SKAR). Staphylococcus aureus was the most common pathogen (37%) followed by coagulase-negative staphylococci (CNS) (23%). Failure was defined as death before the end of antibiotic treatment, revision of major components due to infection, life-long antibiotic treatment, or chronic infection.

Results

The overall healing rate was 75%. The type of infecting pathogen did not statistically significantly affect outcome. Staphylococcal infections treated without a combination of antibiotics including rifampin had a higher failure rate than those treated with rifampin (RR = 4, 95% CI: 2–10). In the 16 cases with more than 3 weeks of symptoms before treatment, the healing rate was 62%, as compared to 77% in the other cases (p = 0.2). The few patients with a revision model of prosthesis at primary operation had a high failure rate (5 of 8).

Interpretation

Good results can be achieved by open debridement with exchange of tibial insert. It is important to use an antibiotic combination including rifampin in staphylococcal infections.Prosthetic joint infection (PJI) is a leading cause of early revision after knee arthroplasty (Portillo et al. 2013, Dalury et al. 2013). Debridement with exchange of modular components is a treatment option that allows retention of the prosthetic components that are fixed to bone.The early experience on debridement of infected knee arthroplasties was summarized in 1993, and the overall success rate of treatment of 377 knees was found to be only 29% (Rand 1993). In 1998, Zimmerli et al. published results of a randomized controlled trial on the role of rifampin for treatment of orthopedic implant-related staphylococcal infections. The cure rate in the group treated with a combination of ciprofloxacin and rifampin was 12/12, as compared to 7/12 in the group treated with ciprofloxacin and placebo. In the algorithms for treatment of PJI published a few years later, debridement with retention of the prosthesis was recommended in early infection where the implant was stable, the soft tissues were not damaged, and rifampin was included in the antibiotic treatment of staphylococcal infections (Zimmerli and Ochsner 2003, Zimmerli et al. 2004). The Swedish Society for Infectious Diseases adopted these recommendations in the Swedish guidelines on musculoskeletal infections published in 2004 and revised in 2008 (Swedish Society for Infectious Diseases 2008).Still, poor results of debridement of knee PJI have been reported in several recent papers from the USA, with a failure rate of 56–64% (Azzam et al. 2010, Gardner et al. 2011, Odum et al. 2011, Fehring et al. 2013). The patient materials in these studies were, however, collected over long periods of time and no information on the antibiotic treatment given was provided. A higher cure rate (three-quarters) was reported in a Spanish study on early staphylococcal infections (in 34 knees and 18 hips) treated with debridement where all except 2 patients received a combination of antibiotics including rifampin (Vilchez et al. 2011). In a larger multicenter study on staphylococcal infections, the cure rate was 55% and the use of rifampin showed a protective effect (Lora-Tamayo et al. 2013).It has been debated how much time may be allowed to elapse from the primary operation or appearance of infection until debridement is performed. In recent guidelines from the Infectious Disease Society of America (IDSA), debridement with retention of the prosthesis is recommended within approximately 30 days of prosthesis implantation or less than 3 weeks of onset of infectious symptoms (Osmon et al. 2013). Furthermore, there is ongoing discussion about whether the results of debridement are affected by the bacterial species causing the infection, and an unfavorable outcome has been reported in infections caused by S. aureus ( Deirmengian et al. 2003, Choi et al. 2011).We investigated the success rate of open debridement and exchange of tibial insert in the treatment of knee PJI in a nationwide material. We also wanted to determine the effects of timing of debridement, bacterial species, and antibiotic treatment.     

Stable fixation of an osseointegated implant system for above-the-knee amputees: titel RSA and radiographic evaluation of migration and bone remodeling in 55 cases

Background and purpose

Rehabilitation of patients with transfemoral amputations is particularly difficult due to problems in using standard socket prostheses. We wanted to assess long-term fixation of the osseointegrated implant system (OPRA) using radiostereometric analysis (RSA) and periprosthetic bone remodeling.

Methods

51 patients with transfemoral amputations (55 implants) were enrolled in an RSA study. RSA and plain radiographs were scheduled at 6 months and at 1, 2, 5, 7, and 10 years after surgery. RSA films were analyzed using UmRSA software. Plain radiographs were graded for bone resorption, cancellization, cortical thinning, and trabecular streaming or buttressing in specifically defined zones around the implant.

Results

At 5 years, the median (SE) migration of the implant was –0.02 (0.06) mm distally. The rotational movement was 0.42 (0.32) degrees around the longitudinal axis. There was no statistically significant difference in median rotation or migration at any follow-up time. Cancellization of the cortex (plain radiographic grading) appeared in at least 1 zone in over half of the patients at 2 years. However, the prevalence of cancellization had decreased by the 5-year follow-up.

Interpretation

The RSA analysis for the OPRA system indicated stable fixation of the implant. The periprosthetic bone remodeling showed similarities with changes seen around uncemented hip stems. The OPRA system is a new and promising approach for addressing the challenges faced by patients with transfemoral amputations.The traditional method of attaching prostheses for patients who have undergone a transfemoral amputation is by means of socket prostheses. Numerous studies have documented the shortcomings of this approach (Hoaglund et al. 1983, Hagberg and Branemark 2001, Hoffman et al. 2002). Skin conditions and volume changes of the stump increase the difficulty in properly attaching and using the prosthesis (Sherman 1999, Collins et al. 2006). In addition, patients experience changes in gait, which reduces hip flexion and extension and increases pelvic tilt (Hagberg et al. 2005, Rabuffetti et al. 2005). There is also a lack of stabilization between the prosthesis and the residual limb.Brånemark introduced the concept of osseointegration in the 1950s (Sullivan 2001). Shortly afterwards, it was applied to human dental implants. Osseointegration was originally defined as “a direct structural and functional connection between ordered living bone and the surface of a load-carrying implant” (Branemark et al. 1977, 2001). This definition has since been modified over the years as follows: “...when there is no progressive relative movement between the implant and the bone with which it has direct contact” (Branemark et al. 2001). Adell et al. (1981) maintained that the fundamental crux and success of osseointegration was threefold: a delicate surgical technique, an adequate recovery period to allow for optimal bony ingrowth, and controlled loading when use of the implant begins. The bone remodeling that occurs around an osseointegrated implant during the carefully controlled rehabilitation permits further integration of the implant into the bone and gives enhanced long-term clinical outcome. The importance of osseointegration for the long-term stability of orthopedic implants has been successfully used in total joint arthroplasty (Engh et al. 2003, Glassman et al. 2006). This approach may provide a stable and functional prosthesis for patients who cannot use a conventional socket prosthesis (Hagberg and Branemark 2009).A number of studies have examined the positive effect of osseointegrated prostheses on the skin around the site and also on joint movement relative to the effect of standard socket prostheses (Hagberg et al. 2005, Lee et al. 2007, Hagberg and Branemark 2009). Increased quality of life, overall well-being, and improved prosthetic usage have been reported (Hagberg et al. 2008).We assessed long-term fixation and stability of the osseointegrated implant using radiostereometric analysis (RSA) and periprosthetic bone remodeling on plain radiographs. Our hypothesis was that there is not substantial micromotion of the implant and that periprosthetic bone remodeling does not have a negative effect on implant stability or performance.     

Hip-inspired implant for revision of failed reverse shoulder arthroplasty with severe glenoid bone loss: Improved clinical outcome in 11 patients at 3-year follow-up

Background and purpose

Glenoid reconstruction and inverted glenoid re-implantation is strongly advocated in revisions of failed reverse shoulder arthroplasty (RSA). Nevertheless, severe glenoid deficiency may preclude glenoid reconstruction and may dictate less favorable solutions, such as conversion to hemiarthropasty or resection arthropasty. The CAD/CAM shoulder (Stanmore Implants, Elstree, UK), a hip arthroplasty-inspired implant, may facilitate glenoid component fixation in these challenging revisions where glenoid reconstruction is not feasible. We questioned (1) whether revision arthroplasty with the CAD/CAM shoulder would alleviate pain and improve shoulder function in patients with failed RSA, not amenable to glenoid reconstruction, (2) whether the CAD/CAM hip-inspired glenoid shell would enable secure and durable glenoid component fixation in these challenging revisions.

Patients and methods

11 patients with failed RSAs and unreconstructable glenoids underwent revision with the CAD/CAM shoulder and were followed-up for mean 35 (28–42) months. Clinical outcomes included the Oxford shoulder score, subjective shoulder value, pain rating, physical examination, and shoulder radiographs.

Results

The average Oxford shoulder score and subjective shoulder value improved statistically significantly after the revision from 50 to 33 points and from 17% to 48% respectively. Pain rating at rest and during activity improved significantly from 5.3 to 2.3 and from 8.1 to 3.8 respectively. Active forward flexion increased from 25 to 54 degrees and external rotation increased from 9 to 21 degrees. 4 patients required reoperation for postoperative complications. No cases of glenoid loosening occurred.

Interpretation

The CAD/CAM shoulder offers an alternative solution for the treatment of failed RSA that is not amenable to glenoid reconstruction.Reverse shoulder arthroplasty (RSA) has become an established treatment for painful and debilitating shoulder pathologies associated with rotator-cuff insufficiency (Boileau et al. 2005, 2006, Frankle et al. 2005). The preoperative condition of shoulders requiring RSA and the technically demanding nature of the procedure make RSA challenging, with an overall complication rate of 15–50% in recently reported series (Guery et al. 2006, Gerber et al. 2009, Kempton et al. 2011). Complications related to the glenoid component (e.g. loosening, mechanical baseplate failure, dissociation) have been reported in 4–16% of cases (Gurey et al. 2006, Fevang et al. 2009, Farshad and Gerber 2010). Aseptic loosening is the most common glenoid-sided complication requiring revision following RSA (Fevang et al. 2009), and is often associated with considerable scapular bone loss (e.g. inferior scapular notching, glenoid deficiency after implant removal), which further complicates surgical revision (Antuna et al. 2001, Boileau et al. 2005, Elhassan et al. 2008, Gerber et al. 2009).Re-implantation of a glenoid component has been found to provide better clinical results than conversion to hemiarthroplasty or resection arthroplasty in revisions of both anatomical (Antuna et al 2001, Elhassan et al. 2008) and reverse shoulder arthroplasties (Farshad et al. 2012, Favard 2013), and it is strongly advocated. However, achievement of secure fixation of a glenoid implant may not be feasible in the presence of severe glenoid bone loss. Glenoid reconstruction with bone graft has been used to facilitate glenoid implant fixation in poor glenoid bone stock in primary shoulder arthroplasty (Hill and Norris 2001) and revision shoulder arthroplasty (Holcomb et al. 2009, Patel et al. 2012). The inconsistent clinical results and durability of fixation achieved with this technique have led to increasing interest in more reliable surgical alternatives for this challenging problem.The CAD/CAM (computer-assisted design/computer-assisted manufacture) shoulder (Stanmore Implants, Elstree, UK) is a constrained hip arthroplasty-inspired shoulder implant that was designed to facilitate glenoid implant fixation by securing a large glenoid shell to the scapula around the deficient glenoid, rather than to the deficient glenoid itself. Unlike Grammont-type implants, the CAD/CAM shoulder has an increased glenohumeral offset (less medialized implant), which has been shown to improve rotational movements of the shoulder (by recruiting anterior and posterior deltoid fibers and re-tensioning of the remaining rotator cuff) and to minimize scapular notching (Holcomb et al. 2009, Valenti et al. 2011)The purpose of this study was (1) to determine whether revision arthroplasty with the CAD/CAM shoulder would alleviate pain and improve shoulder function in patients with failed RSA and severe glenoid deficiency that is not amenable to reconstruction and inverted glenoid re-implantation; and (2) to determine whether the CAD/CAM hip-inspired glenoid shell would enable secure and durable glenoid component fixation in these challenging revisions. To our knowledge, no previous study has evaluated the use of such implants in revision surgery for failed glenoid-deficient RSA.     

Infection after primary hip arthroplasty: a comparison of 3 Norwegian health registers

Background and purpose

The aim of the present study was to assess incidence of and risk factors for infection after hip arthroplasty in data from 3 national health registries. We investigated differences in risk patterns between surgical site infection (SSI) and revision due to infection after primary total hip arthroplasty (THA) and hemiarthroplasty (HA).

Materials and methods

This observational study was based on prospective data from 2005–2009 on primary THAs and HAs from the Norwegian Arthroplasty Register (NAR), the Norwegian Hip Fracture Register (NHFR), and the Norwegian Surveillance System for Healthcare–Associated Infections (NOIS). The Norwegian Patient Register (NPR) was used for evaluation of case reporting. Cox regression analyses were performed with revision due to infection as endpoint for data from the NAR and the NHFR, and with SSI as the endpoint for data from the NOIS.

Results

The 1–year incidence of SSI in the NOIS was 3.0% after THA (167/5,540) and 7.3% after HA (103/1,416). The 1–year incidence of revision due to infection was 0.7% for THAs in the NAR (182/24,512) and 1.5% for HAs in the NHFR (128/8,262). Risk factors for SSI after THA were advanced age, ASA class higher than 2, and short duration of surgery. For THA, the risk factors for revision due to infection were male sex, advanced age, ASA class higher than 1, emergency surgery, uncemented fixation, and a National Nosocomial Infection Surveillance (NNIS) risk index of 2 or more. For HAs inserted after fracture, age less than 60 and short duration of surgery were risk factors of revision due to infection.

Interpretation

The incidences of SSI and revision due to infection after primary hip replacements in Norway are similar to those in other countries. There may be differences in risk pattern between SSI and revision due to infection after arthroplasty. The risk patterns for revision due to infection appear to be different for HA and THA.Increasing incidence of revision due to infection after primary total hip arthroplasty (THA) has been observed in different countries during the last decade (Kurtz et al. 2008, Dale et al. 2009, Pedersen et al. 2010). There have been several studies on incidence of and risk factors for infection based on data from surveillance systems (Ridgeway et al. 2005, Mannien et al. 2008), arthroplasty (quality) registers (Berbari et al. 1998, Dale et al. 2009, Pedersen et al. 2010), and administrative databases (Mahomed et al. 2003, Kurtz et al. 2008, Ong et al. 2009). There have been reviews on incidence of and risk factors for infection after hip arthroplasty, based on publications from databases with different definitions of infection (Urquhart et al. 2009, Jämsen et al. 2010a). Superficial surgical site infections (SSIs) may have risk factors that are different from those of full surgical revisions due to infection. Furthermore, THA and hip hemiarthroplasty (HA) may have different patterns of risk of infection (Ridgeway et al. 2005, Cordero–Ampuero and de Dios 2010).In the present study, we used data from 3 national health registries in Norway to assess incidence and some risk factors for infection after primary hip arthroplasty. Differences in risk patterns between SSI and revision due to infection were investigated for HA and THA.     

Hospital volume affects outcome after total knee arthroplasty: A nationwide registry analysis of 80 hospitals and 59,696 replacements

ResultsThe greater the volume of the hospital, the shorter was the average LOS and LUIC. Smaller hospital volume was not unambiguously associated with increased revision, re-admission, or MUA rates. The smaller the annual hospital volume, the more often patients were discharged home.InterpretationLOS and LUIC ought to be shortened in lower-volume hospitals. There is potential for a reduction in length of stay in extended institutional care facilities.Total knee replacement (TKR) is one of the most common orthopedic procedures, and it is expected to increase markedly in volume (Kurtz et al. 2007). Due to the potentially severe complications and the high economic impact of the procedure, efforts to minimize the risks and optimize perioperative efficiency are important.It has been suggested that increased hospital volume and reduction in length of stay (LOS) at the operating hospital after TKR are related, but there is no consensus (Yasunaga et al. 2009, Marlow et al. 2010, Paterson et al. 2010, Bozic et al. 2010, Styron et al. 2011). In addition, results on the association of hospital volume with re-admission rates (Soohoo et al. 2006b, Judge et al. 2006, Bozic et al. 2010, Cram et al. 2011) and revision risk have been inconclusive (Shervin et al. 2007, Manley et al. 2009, Bozic et al. 2010, Paterson et al. 2010). No-one has tried to study the association between length of uninterrupted institutional care (LUIC), incidence of manipulation under anesthesia (MUA) after TKR, and hospital volume.By combining 5 national-level registries, we examined possible associations between hospital volume and LOS, LUIC, discharge disposition, number of re-admissions within 14 and 42 days, MUA, and revisions after TKR for all knee arthroplasties performed in Finland between 1998 and 2010.     

No clinical benefit of gender-specific total knee arthroplasty: A systematic review and meta-analysis of 6 randomized controlled trials

Background and purpose

There is no consensus regarding the clinical relevance of gender-specific prostheses in total knee arthroplasty (TKA). We summarize the current best evidence in a comparison of clinical and radiographic outcomes between gender-specific prostheses and standard unisex prostheses in female patients.

Methods

We used the PubMed, Embase, Cochrane, Science Citation Index, and Scopus databases. We included randomized controlled trials published up to January 2013 that compared gender-specific prostheses with standard unisex prostheses in female patients who underwent primary TKAs.

Results

6 trials involving 423 patients with 846 knee joints met the inclusion criteria. No statistically significant differences were observed between the 2 designs regarding pain, range of motion (ROM), knee scores, satisfaction, preference, complications, and radiographic results. The gender-specific design (Gender Solutions; Zimmer Inc, Warsaw, Indiana) reduced the prevalence of overhang. However, it had less overall coverage of the femoral condyles compared to the unisex group. In fact, the femoral prosthesis in the standard unisex group matched better than that in the gender-specific group.

Interpretation

Gender-specific prostheses do not appear to confer any benefit in terms of clinician- and patient-reported outcomes for the female knee.Women account for almost two-thirds of knee arthroplasties (Kurtz et al. 2007). Recently, a possible effect of gender on functional outcomes and implant survivorship has been identified (Vincent et al. 2006, Ritter et al. 2008, Kamath et al. 2010, Parsley et al. 2010, O’Connor 2011). Gender differences in the anatomy of the distal femur are well documented (Conley et al. 2007, Yue et al. 2011a, b, Yan et al. 2012, Zeng et al. 2012). Women tend to have a less prominent anterior condyle (Conley et al. 2007, Fehring et al. 2009), a higher quadriceps angle (Q-angle) (Hsu et al. 1990, Woodland et al. 1992), and a reduced mediolateral to anteroposterior aspect ratio (Chin et al. 2002, Chaichankul et al. 2011). Investigators have found that standard unisex knee prostheses may not equally match the native anatomy in male and female knees (Clarke and Hentz 2008, Yan et al. 2012). A positive association between the femoral component size and the amount of overhang was observed in females, and femoral component overhang (≥ 3 mm) may result in postoperative knee pain or reduced ROM (Hitt et al. 2003, Lo et al. 2003, Mahoney et al. 2010).The concept of gender-specific knee prostheses was introduced to match these 3 anatomic differences in the female population (Conley et al. 2007). It includes a narrower mediolateral diameter for a given anteroposterior dimension, to match the female knee more closely. Additionally, the anterior flange of the prothesis was modified to include a recessed patellar sulcus and reduced anterior condylar height (to ovoid “overstuffing” during knee flexion) and a lateralized patellar sulcus (to accommodate the increased Q-angle associated with a wider pelvis).Several randomized controlled trials (RCTs) have failed to establish the superiority of the gender-specific prosthesis over the unisex knee prosthesis in the female knee (Kim et al. 2010a, b, Song et al. 2012a, Thomsen et al. 2012, von Roth et al. 2013). In contrast, other studies have found higher patient satisfaction and better radiographic fit in the gender-specific TKAs than in the standard unisex TKAs (Clarke and Hentz 2008, Parratte et al. 2011, Yue et al. 2014). We therefore performed a systematic review and meta-analysis to compare the clinical and radiographic results of TKA in female patients receiving gender-specific prostheses or standard unisex prostheses.     

Survival and prognostic factors in chondrosarcoma: results in 115 patients with long-term follow-up

Background and purpose

There have been few long-term studies on the outcome of chondrosarcoma and the findings regarding prognostic factors are controversial. We examined a homogeneous group of patients with primary central chondrosarcoma of bone who were treated according to a uniform surgical protocol at our institution, in order to determine the factors that influence survival and identify potential improvements to our therapeutic algorithm.

Patients and methods

We performed a retrospective analysis of 115 patients with primary central chondrosarcoma of bone who presented with localized disease and who had a minimum follow-up of 5 years after diagnosis. 68 tumors were localized in the extremities and 47 in the axial skeleton or pelvis. 59 patients had a high-grade (II and III) and 56 a low-grade (I) tumor. 94 patients underwent surgical resection with adequate (wide or radical) margins, while 21 patients had inadequate (marginal or intralesional) margins.

Results

Tumor grade and localization were found to be statistically significant independent predictors of disease-related deaths in multivariate analysis. The quality of surgical margins did not influence survival. The AJCC staging system was able to predict prognosis in patients with chondrosarcoma of the extremities, but not in those with tumors of the axial skeleton and pelvis. Long-term survival after secondary metastatic disease was only observed when metastases were resected with wide margins. Patients with metastases who received further treatment with conventional chemotherapy, radiotherapy, and/or further surgery had significantly better survival compared to those who received best supportive care.

Interpretation

The outcome in patients with primary central chondrosarcoma of bone who present with localized disease is mostly affected by tumor-related parameters.Chondrosarcoma is the second most common primary malignant solid tumor of bone, and accounts for approximately 25% of all bone sarcomas (Bertoni et al. 2002). It is largely considered to be resistant to conventional chemotherapy and radiotherapy (Healey and Lane 1986, Campanacci 1999, Gelderbloom et al. 2008). As such, surgical resection has been the cornerstone of treatment for over 50 years (Dahlin and Henderson 1956, Healey and Lane 1986, Gelderbloom et al. 2008). However, in recent years several novel therapeutic approaches have been evaluated in experimental studies (Morioka et al. 2003, Gouin et al. 2006, Klenke et al. 2007, Delaney et al. 2009, Schrage et al. 2009, 2010).There is no consensus on prognostic factors to determine which patients have a higher risk of treatment failure and disease-related deaths, although several papers have addressed this issue (Evans et al. 1977, Pritchard et al. 1980, Gitelis et al. 1981, Björnsson et al. 1998, Lee et al. 1999, Rizzo et al. 2001, Fiorenza et al. 2002). One reason may be that most studies have included patients treated over several decades, with no account for the different surgical criteria, indications, and methods applied over the years. Furthermore, most studies have included patients with short follow-up, despite the fact that a high rate of late recurrence and metastasis has been reported for chondrosarcoma patients compared to those with other primary bone sarcomas (Evans et al. 1977, Pritchard et al. 1980), as well as patients with rare histopathological subtypes that have a distinct biologic behavior (Lee et al. 1999, Bertoni et al. 2002, Gelderbloom et al. 2008) such as dedifferentiated chondrosarcoma, mesenchymal chondrosarcoma, and clear cell chondrosarcoma, thus reducing the validity of the results.The purpose of this long-term retrospective study was to examine a group of patients with primary central chondrosarcoma of bone who presented with localized disease and were treated with a uniform surgical protocol at our institution, in order to determine the factors that influence overall and event-free survival. We further aimed at identifying potential improvements to our therapeutic algorithm.     

More accurate component alignment in navigated total knee arthroplasty has no clinical benefit at 5-year follow-up

Background and purpose

Computer navigation in total knee arthroplasty is somewhat controversial. We have previously shown that femoral component positioning is more accurate with computed navigation than with conventional implantation techniques, but the clinical impact of this is unknown. We now report the 5-year outcome of our previously reported 2-year outcome study.

Methods

78 of initially 84 patients (80 of 86 knees) were clinically and radiographically reassessed 5 (5.1–5.9) years after conventional, image-based, and image-free total knee arthroplasty. The methodology was identical to that used preoperatively and at 2 years, including the Knee Society score (KSS) and the functional score (FS), and AP and true lateral standard radiographs.

Results

Although a more accurate femoral component positioning in the navigated groups was obtained, clinical outcome, number of reoperations, KSS, FS, and range of motion were similar between the groups.

Interpretation

The increased costs and time for navigated techniques did not translate into better functional and subjective medium-term outcome compared to conventional techniques.Abnormal wear patterns and component loosening are mainly results of component malalignment and complications of the extensor mechanism, the most common reasons for early failure of TKA (Ritter et al. 1994, Rand et al. 2003, Vince 2003, Bathis et al. 2004). It has been suggested that a varus or valgus malalignment of more the 3° leads to faster wear and debris, followed by early failure of TKA (Ecker et al. 1987, Archibeck and White 2003, Nizard et al. 2004).Several surgical navigation systems for TKA have been introduced to optimize component positioning (Delp et al. 1998, DiGioia et al. 1998, Krackow et al. 1999). It has been shown that navigation provides a more precise component positioning and fewer outliers (Bathis et al. 2004, Nabeyama et al. 2004, Stockl et al. 2004, Victor and Hoste 2004, Anderson et al. 2005, Zumstein et al. 2006). Nevertheless, comparing computer-navigated total knee arthroplasty with conventional implantation techniques, there is no evidence in the current literature of any significant improvement in clinical outcome and in component loosening (Bathis et al. 2004, Jenny et al. 2005, Yau et al. 2005, Bonutti et al. 2008, Molfetta and Caldo 2008).In a prospective study involving 86 patients in 3 different groups (image-based navigation, image-free navigation, and conventional), we showed that femoral component positioning was more accurate with navigation than with conventional implantation techniques, but tibial positioning showed similar results (Zumstein et al. 2006).Although other medium-term data on navigated total knee arthroplasty have already been reported (Ishida et al. 2011, Schmitt et al. 2011), there has been no prospective cohort series with reporting of the clinical, functional, and radiographic outcome with all 3 techniques: image-based navigated, image-free navigated, or conventional TKA. We therefore determined the clinical, functional, and radiographic 5-year results after each of the 3 techniques.     

Role of preoperative pain,muscle function,and activity level in discharge readiness after fast-track hip and knee arthroplasty

Methods Before surgery, hip pain (THA) or knee pain (TKA), lower-extremity muscle power, functional performance, and physical activity were assessed in a sample of 150 patients and used as independent variables to predict the outcome (dependent variable)—readiness for hospital discharge —for each type of surgery. Discharge readiness was assessed twice daily by blinded assessors.Results Median discharge readiness and actual length of stay until discharge were both 2 days. Univariate linear regression followed by multiple linear regression revealed that age was the only independent predictor of discharge readiness in THA and TKA, but the standardized coefficients were small (≤ 0.03).Interpretation These results support the idea that fast-track THA and TKA with a length of stay of about 2–4 days can be achieved for most patients independently of preoperative functional characteristics.Over the last decade, length of stay (LOS) with discharge to home after primary THA and TKA has declined from about 5–10 days to about 2–4 days in selected series and larger nationwide series (Malviya et al. 2011, Raphael et al. 2011, Husted et al. 2012, Kehlet 2013, Hartog et al. 2013, Jørgensen and Kehlet 2013). However, there is a continuing debate about whether selected patients only or all patients should be scheduled for “fast-track” THA and TKA in relation to psychosocial factors and preoperative pain and functional status (Schneider et al. 2009, Hollowell et al. 2010, Macdonald et al. 2010, Antrobus and Bryson 2011, Jørgensen and Kehlet 2013), or whether organizational or pathophysiological factors in relation to the surgical trauma may determine the length of stay (Husted et al. 2011, Husted 2012).We studied the role of THA and TKA patients’ preoperative pain and functional characteristics in discharge from 2 orthopedic departments with well-established fast-track recovery regimens (Husted et al. 2010).     

Total shoulder arthroplasty does not correct the orientation of the eroded glenoid

Background and purpose

Alignment of the glenoid component with the scapula during total shoulder arthroplasty (TSA) is challenging due to glenoid erosion and lack of both bone stock and guiding landmarks. We determined the extent to which the implant position is governed by the preoperative erosion of the glenoid. Also, we investigated whether excessive erosion of the glenoid is associated with perforation of the glenoid vault.

Methods

We used preoperative and postoperative CT scans of 29 TSAs to assess version, inclination, rotation, and offset of the glenoid relative to the scapula plane. The position of the implant keel within the glenoid vault was classified into three types: centrally positioned, component touching vault cortex, and perforation of the cortex.

Results

Preoperative glenoid erosion was statistically significantly linked to the postoperative placement of the implant regarding all position parameters. Retroversion of the eroded glenoid was on average 10° (SD10) and retroversion of the implant after surgery was 7° (SD11). The implant keel was centered within the vault in 7 of 29 patients and the glenoid vault was perforated in 5 patients. Anterior cortex perforation was most frequent and was associated with severe preoperative posterior erosion, causing implant retroversion.

Interpretation

The position of the glenoid component reflected the preoperative erosion and “correction” was not a characteristic of the reconstructive surgery. Severe erosion appears to be linked to vault perforation. If malalignment and perforation are associated with loosening, our results suggest reorientation of the implant relative to the eroded surface.Based on 2,540 shoulder arthroplasties, Bohsali et al. (2006) reported the aseptic loosening rate to be 39%. Many other studies have shown that implant malalignment may cause high radiographic loosening rates (Franklin et al. 1988, Nyffeler et al. 2003, Farron et al. 2006, Habermeyer et al. 2006, Hopkins et al. 2007, Shapiro et al. 2007).Glenoid implant positioning is a challenging procedure. Reasons include poor intraoperative glenoid exposure, lack of reference landmarks, and the surgeon being (mis)guided by the orientation of the eroded glenoid surface. Friedman et al. (1992) and Walch et al. (1999) found that due to osteoarthritic erosions, the preoperative glenoid was retroverted by more than 10°. Walch et al. (1999) observed that in 24% of total shoulder arthroplasties (TSAs) the preoperative retroversion was excessive due to arthritic changes showing on average 23° of retroversion. It seems likely that such deformed glenoid bone will cause malpositioning of glenoid implants. A particular consequence of this is that erosion may lead to an implant position that perforates the glenoid vault (Yian et al. 2005).In anatomical studies, normal glenoid version has been found to vary within a range of about 20°, with an average retroversion of 1–2° (Churchill et al. 2001, Kwon et al. 2005, Codsi et al. 2008). Without knowing the patient native version, the aim of TSA is to position the prosthesis in a neutral orientation, correcting for pre-existing erosion of the glenoid when possible.We hypothesized that in routine surgical practice, the position of the implant is determined by the preoperative orientation of the glenoid and surgery does not achieve neutral positioning. A second hypothesis was that excessive erosion of the glenoid would be associated with perforation of the glenoid vault by the implant, which may have important implications for the success of the arthroplasty.