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).     

Pain control after total knee arthroplasty: a randomized trial comparing local infiltration anesthesia and continuous femoral block

Background and purpose

Pain after total knee arthroplasty (TKA) is usually severe, and epidural analgesia or femoral nerve block has been considered to be an effective pain treatment. Recently, local infiltration analgesia (LIA) has become increasingly popular but the outcome of this method regarding the analgesic effect has not been fully evaluated. We compared local infiltration analgesia and femoral block with regard to analgesia and morphine demand during the first 24 h after TKA.

Methods

40 patients undergoing TKA under spinal anesthesia were randomized to receive femoral nerve block (group F) or peri- and intraarticular infiltration analgesia (group LIA) with a mixture containing ropivacaine, ketorolac, and epinephrine. All patients had access to intravenous patient-controlled analgesia (PCA) with morphine postoperatively. Pain intensity at rest and upon movement was assessed on a numeric rating scale (0–10) on an hourly basis over 24 h if the patients were awake.

Results

The average pain at rest was marginally lower with LIA (1.6) than with femoral block (2.2). Total morphine consumption per kg was similar between the 2 groups. Ancillary analysis revealed that 1 of 20 patients in the LIA group reported a pain intensity of > 7 upon movement, as compared to 7 out of 19 in the femoral block group (p = 0.04).

Interpretation

Both LIA and femoral block provide good analgesia after TKA. LIA may be considered to be superior to femoral block since it is cheaper and easier to perform.Pain after total knee arthroplasty (TKA) is usually severe and difficult to manage, and insufficient pain relief may delay recovery. The most effective pain treatment has traditionally been epidural analgesia or femoral nerve block (Singelyn et al. 1998, Ganapathy et al. 1999, Chelly et al. 2001, Davies et al. 2004, Ilfeld et al. 2006) in combination with opioid analgesics and non-steroidal anti-inflammatory drugs (NSAIDs, cyclooxygenase (cox) inhibitors). Each of these methods has its specific side effects. Urinary retention and muscular weakness are often reported after epidural analgesia. Unpleasant numbness of a large part of the lower extremity is common after femoral block. Opioid analgesics often cause sedation, nausea and vomiting, and also urinary retention. Non-selective cox inhibitors may cause gastrointestinal bleeding, renal complications, and epidural hematoma, especially in combination with anti-thrombotic prophylaxis with low-molecular-weight heparin (Afzal et al. 2006).An alternative method for postoperative pain relief after TKA, which has attracted growing interest in recent years, is multimodal wound infiltration analgesic technique consisting of peri- and intraarticular infiltration of local anesthetics and NSAID in the knee (LIA) (Andersen et al. 2008a, b, Kerr and Kohan 2008). This technique appears to offer several advantages over traditional methods, since the analgesia affects only the surgical area with limited interference of the muscle strength. Thus, easier rehabilitation of the operated extremity and earlier discharge from the hospital can be expected (Reilly et al. 2005, Essving et al. 2009). Furthermore, recent studies have shown that the LIA technique reduces the requirement for postoperative analgesia with opioids (Tanaka et al. 2001, Busch et al. 2006, Vendittoli et al. 2006).Only a few investigators have randomly compared LIA with other methods with proven analgesic effect, such as femoral block or epidural analgesia (Parvataneni et al. 2007, Toftdahl et al 2007). Parvatanemi and collaborators (2007) have shown that a combination of a femoral block and local administration of bupivacaine, morphine, and epinephrine results in better pain relief and patient satisfaction than femoral block. Toftdahl and collaborators (2007) presented data suggesting that LIA with ropivacaine, ketorolac, and epinephrine results in faster postoperative activation, as indicated by being better able to walk more than 3 m on the first postoperative day as compared to femoral block. A retrospective comparison (DeWeese et al. 2001) indicated that epidural anesthesia with fentanyl and bupivacaine resulted in better pain relief and less use of other analgesics than did continuous infiltration of the knee with bupivacaine.Femoral block is known to be an effective pain treatment after TKA (Szczukowski et al. 2004, Navas et al. 2005, Duarte et al. 2006). We compared the LIA technique with femoral block regarding efficacy of pain management at rest and upon movement after TKA. We also investigated whether LIA reduced the demand for intravenous morphine, administered via a patient-controlled analgesia (PCA) pump during the first 24 h postoperatively.     

Why still in hospital after fast-track hip and knee arthroplasty?

Background and purpose

Length of stay (LOS) following total hip and knee arthroplasty (THA and TKA) has been reduced to about 3 days in fast-track setups with functional discharge criteria. Earlier studies have identified patient characteristics predicting LOS, but little is known about specific reasons for being hospitalized following fast-track THA and TKA.

Patients and methods

To determine clinical and logistical factors that keep patients in hospital for the first postoperative 24–72 hours, we performed a cohort study of consecutive, unselected patients undergoing unilateral primary THA (n = 98) or TKA (n = 109). Median length of stay was 2 days. Patients were operated with spinal anesthesia and received multimodal analgesia with paracetamol, a COX-2 inhibitor, and gabapentin—with opioid only on request. Fulfillment of functional discharge criteria was assessed twice daily and specified reasons for not allowing discharge were registered.

Results

Pain, dizziness, and general weakness were the main clinical reasons for being hospitalized at 24 and 48 hours postoperatively while nausea, vomiting, confusion, and sedation delayed discharge to a minimal extent. Waiting for blood transfusion (when needed), for start of physiotherapy, and for postoperative radiographic examination delayed discharge in one fifth of the patients.

Interpretation

Future efforts to enhance recovery and reduce length of stay after THA and TKA should focus on analgesia, prevention of orthostatism, and rapid recovery of muscle function.Total hip and total knee arthroplasty (THA and TKA) are frequent operations with an average length of stay (LOS) of about 6–12 days in the United Kingdom, Germany, and Denmark (Husted et al. 2006, Bundesauswertung 2009, NHS 2010).During the last decade, however, there has been increased interest in optimal multimodal perioperative care to enhance recovery (the fast-track methodology). Improvement of analgesia; reduction of surgical stress responses and organ dysfunctions including nausea, vomiting, and ileus; early mobilization; and oral nutrition have been of particular interest (Kehlet 2008, Kehlet and Wilmore 2008). These principles have also been applied to THA and TKA, resulting in improvements in pain treatment with multimodal opioid-sparing regimens including a local anesthetic infiltration technique (LIA) or peripheral nerve blocks to facilitate early mobilization (Ilfeld et al. 2006a, b, 2010a, Andersen et al. 2008, Kerr and Kohan 2008), and allowing functional rehabilitation to be initiated a few hours postoperatively (Holm et al. 2010)—ultimately leading to a reduction in LOS (Husted et al. 2008, Barbieri et al. 2009, Husted et al. 2010a, b). Using these evidence-based regimens combined with an improved logistical setup, LOS is reduced to about 2–4 days (Kerr and Kohan 2008, Husted et al. 2010 a,b,c, Lunn et al. 2011).Having well-defined functional discharge criteria is imperative in order to ensure a safe discharge—and it is mandatory if meaningful comparison of LOS is done following alterations in the track (Husted et al. 2008). In the same fast-track setting, an earlier study focused on patient characteristics predicting LOS (Husted et al. 2008). However, little is known about the specific reasons for why patients are hospitalized during the first 1–3 days after THA or TKA; i.e. why can patients not be discharged?We therefore analyzed clinical and organizational factors responsible for being hospitalized in a well-defined prospective setup in a fast-track unit. This unit had previously documented LOS of about 2–3 days (Andersen et al. 2008, Holm et al. 2010, Husted et al. 2010b, c, Lunn et al. 2011).     

High-volume infiltration analgesia in bilateral hip arthroplasty. A randomized, double-blind placebo-controlled trial

Background and purpose

High-volume infiltration analgesia may be effective in postoperative pain management after hip arthroplasty but methodological problems prevent exact interpretation of previous studies.

Methods

In a randomized, double-blind placebo-controlled trial in 12 patients undergoing bilateral total hip arthroplasty (THA) in a fast-track setting, saline or high-volume (170 mL) ropivacaine (0.2%) with epinephrine (1:100,000) was administered to the wound intraoperatively along with supplementary postoperative injections via an intraarticular epidural catheter. Oral analgesia was instituted preoperatively with a multimodal regimen (gabapentin, celecoxib, and acetaminophen). Pain was assessed repeatedly for 48 hours postoperatively, at rest and with 45° hip flexion.

Results

Pain scores were low and similar between ropivacaine and saline administration. Median hospital stay was 4 (range 2–7) days.

Interpretation

Intraoperative high-volume infiltration with 0.2% ropivacaine with repeated intraarticular injections postoperatively may not give a clinically relevant analgesic effect in THA when combined with a multimodal oral analgesic regimen with gabapentin, celecoxib, and acetaminophen.Continuous epidural analgesia (Choi et al. 2003) or continuous or single-shot peripheral nerve blocks (Boezaart 2006, Ilfeld et al. 2008) may provide sufficient analgesia after total hip arthroplasty (THA), but both techniques are associated with potential motor blockade, thereby hindering early rehabilitation (Choi et al 2003, Boezaart 2006, Ilfeld et al. 2008).Local infiltration analgesia (LIA) (Röstlund and Kehlet 2007, Kerr and Kohan 2008, Otte et al. 2008) with intraoperative infiltration of local anesthetic in the surgical wound and subsequent supplementary postoperative intraarticular or wound injections has been reported to be effective in knee arthroplasty (Andersen et al. 2008). However, for THA only limited and inconclusive data are available from placebo-controlled and randomized trials (Bianconi et al. 2003, Andersen et al. 2007 a, b, Busch et al. 2010) and from non-randomized cohort studies (Kerr and Kohan 2008, Otte et al. 2008). We therefore decided to evaluate the analgesic efficacy of LIA in a placebo-controlled, randomized and double-blind trial in fast-track bilateral hip arthroplasty with administration of either ropivacaine or saline to the wound, thereby limiting the large inter-individual pain response to THA. This design has proven valid in assessing the analgesic value of LIA in TKA (Andersen et al. 2008). The primary endpoint was pain on flexion of the hip joint 8 hours postoperatively.     

Fast-track revision knee arthroplasty. A feasibility study

Background and purpose

Fast-track surgery has reduced the length of hospital stay (LOS), morbidity, and convalescence in primary hip and knee arthroplasty (TKA). We assessed whether patients undergoing revision TKA for non-septic indications might also benefit from fast-track surgery.

Methods

29 patients were operated with 30 revision arthroplasties. Median age was 67 (34–84) years. All patients followed a standardized fast-track set-up designed for primary TKA. We determined the outcome regarding LOS, morbidity, mortality, and satisfaction.

Results

Median LOS was 2 (1–4) days excluding 1 patient, who was transferred to another hospital for logistical reasons (10 days). None of the patients died within 3 months, and 3 patients were re-admitted (2 for suspicion of DVT, which was not found, and 1 for joint mobilization). Patient satisfaction was high.

Interpretation

Patients undergoing revision TKA for non-septic reasons may be included in fast-track protocols. Outcome appears to be similar to that of primary TKA regarding LOS, morbidity, and satisfaction. Our findings call for larger confirmatory studies and studies involving other indications (revision THA, 1-stage septic revisions).For more than a decade, favorable outcomes following fast-track protocols rather than more conventional hospital stays have been reported from numerous studies on primary THA and TKA. In the last few years, outcomes have been further improved, mainly due to improved multimodal opioid-sparing analgesia and early mobilization, allowing patients to fulfill functional discharge criteria within 2–3 days (Husted et al. 2008, 2010 a,b,c,d, Larsen et al. 2008 a,b,c, 2009, Andersen et al. 2009, Barbieri et al. 2009, Rotter et al. 2010). The addition of local infiltration analgesia (LIA) has improved early analgesia and facilitated early recovery, allowing patients to ambulate with full weight bearing within 2–3 hours of surgery (Andersen et al. 2008 a,b, 2009, Holm et al. 2010).So far, however, no one has reported the potential benefits of the fast-track methodology (including multimodal opioid-sparing analgesia, perioperative LIA, and early mobilization) for revision TKA, with its more extensive surgical trauma leading to a corresponding increase in the surgical stress responses. We therefore investigated the feasibility of our well-documented fast-track primary TKA program on a consecutive cohort of revision TKA patients.     

Removal of restrictions following primary THA with posterolateral approach does not increase the risk of early dislocation

Background and purpose

Patient education and mobilization restrictions are often used in an attempt to reduce the risk of dislocation following primary THA. To date, there have been no studies investigating the safety of removal of mobilization restrictions following THA performed using a posterolateral approach. In this retrospective non-inferiority study, we investigated the rate of early dislocation following primary THA in an unselected patient cohort before and after removal of postoperative mobilization restrictions.

Patients and methods

From the Danish National Health Registry, we identified patients with early dislocation in 2 consecutive and unselected cohorts of patients who received primary THA at our institution from 2004 through 2008 (n = 946) and from 2010 through 2014 (n = 1,329). Patients in the first cohort were mobilized with functional restrictions following primary THA whereas patients in the second cohort were allowed unrestricted mobilization. Risk of early dislocation (within 90 days) was compared in the 2 groups and odds ratio (OR)—adjusted for possible confounders—was calculated. Reasons for early dislocation in the 2 groups were identified.

Results

When we adjusted for potential confounders, we found no increased risk of early dislocation within 90 days in patients who were mobilized without restrictions. Risk of dislocation within 90 days was lower (3.4% vs 2.8%), risk of dislocation within 30 days was lower (2.1% vs 2.0%), and risk of multiple dislocations (1.8% vs 1.1%) was lower in patients who were mobilized without restrictions, but not statistically significantly so. Increasing age was an independent risk factor for dislocation.

Interpretation

Removal of mobilization restrictions from the mobilization protocol following primary THA performed with a posterolateral approach did not lead to an increased risk of dislocation within 90 days.Dislocation of the hip is one of the most common complications following total hip arthroplasty (THA), with reported incidence rates ranging from less than 1% to over 15%, and higher risk of dislocation after revision arthroplasty than after primary THA (Woo and Morrey 1982, Phillips et al. 2003, Khatod et al. 2006, Patel et al. 2007). Several patient-related and surgery-related parameters, such as age (Ali Khan et al. 1981), cognitive function (Fackler and Poss 1980, Jolles et al. 2002), component malposition (Lewinnek et al. 1978, Jolles et al. 2002, Nishii et al. 2004), surgical approach (Masonis and Bourne 2002) and soft-tissue related factors (White et al. 2001) contribute to the risk of dislocation. In the past, many surgeons have used patient education and postoperative mobilization restrictions in an attempt to reduce this risk (Woo and Morrey 1982, Morrey 1992, 1997). However, in recent years some authors have questioned the benefit of such restrictions (Peak et al. 2005, Restrepo et al. 2011) and no published studies have ever confirmed a reduction in dislocation using restrictions, making some authors question the value of postoperative restrictions (Husted et al. 2014).A possible limitation of these studies was that they all investigated primary THA performed using the anterolateral approach, which is probably associated with a lower rate of dislocation than primary THA using the posterior approach (Masonis and Bourne 2002). One recent study investigated a reduction in movement restrictions following primary THA with the posterolateral approach and found that fewer movement restrictions did not affect the patient-reported outcomes after 6 weeks, and led to earlier return to work. However, no recommendations on safety issues could be made due to the low number of patients (Mikkelsen et al. 2014).The main aim of this retrospective, non-inferiority study was to investigate the rate of early dislocation (within 90 days) following primary THA in an unselected patient cohort before and after removal of postoperative mobilization restrictions. We also investigated the reasons for dislocation in patients who were mobilized with and without restrictions.     

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.     

Worse patient-reported outcome after lateral approach than after anterior and posterolateral approach in primary hip arthroplasty: A cross-sectional questionnaire study of 1,476 patients 1–3 years after surgery

Background

The surgical approach in total hip arthroplasty (THA) is often based on surgeon preference and local traditions. The anterior muscle-sparing approach has recently gained popularity in Europe. We tested the hypothesis that patient satisfaction, pain, function, and health-related quality of life (HRQoL) after THA is not related to the surgical approach.

Patients

1,476 patients identified through the Norwegian Arthroplasty Register were sent questionnaires 1–3 years after undergoing THA in the period from January 2008 to June 2010. Patient-reported outcome measures (PROMs) included the hip disability osteoarthritis outcome score (HOOS), the Western Ontario and McMaster Universities osteoarthritis index (WOMAC), health-related quality of life (EQ-5D-3L), visual analog scales (VAS) addressing pain and satisfaction, and questions about complications. 1,273 patients completed the questionnaires and were included in the analysis.

Results

Adjusted HOOS scores for pain, other symptoms, activities of daily living (ADL), sport/recreation, and quality of life were significantly worse (p < 0.001 to p = 0.03) for the lateral approach than for the anterior approach and the posterolateral approach (mean differences: 3.2–5.0). These results were related to more patient-reported limping with the lateral approach than with the anterior and posterolateral approaches (25% vs. 12% and 13%, respectively; p < 0.001).

Interpretation

Patients operated with the lateral approach reported worse outcomes 1–3 years after THA surgery. Self-reported limping occurred twice as often in patients who underwent THA with a lateral approach than in those who underwent THA with an anterior or posterolateral approach. There were no significant differences in patient-reported outcomes after THA between those who underwent THA with a posterolateral approach and those who underwent THA with an anterior approach.The approach used for total hip arthroplasty (THA) is often based on the surgeon’s preference and local traditions. In 2011, 7,360 primary THAs were reported to the Norwegian Arthroplasty Register (NAR) (Norwegian Arthroplasty Register Annual Report 2012). A lateral approach was used in 53% of the operations, the posterolateral approach in 28%, and an anterior approach in 16%. Anterior muscle-sparing approaches have gained popularity because it has been argued that patients with such surgical approaches have less pain, shorter length of stay, and shorter rehabilitation time. These are short-term effects (Rodriguez et al. 2014), and the long-term effects are not well documented.The anterior approaches used in Norway are either a modified Smith-Petersen approach (Smith-Petersen 1949, Judet and Judet 1950) or an anterolateral Watson-Jones approach (Watson-Jones 1936). These may have a longer learning curve (Greidanus et al. 2013) and a higher incidence of early revision (Spaans et al. 2012, Lindgren et al. 2012). The lateral approach (Hardinge 1982) divides the anterior portion of gluteus medius and minimus. Muscular-tendon suture or osteosuture is used to reinsert the tendon into the trochanteric area. This approach has been blamed for increasing the risk of damage to the superior gluteal nerve and to the gluteus medius muscle (Jolles and Bogoch 2006, Arthursson et al. 2007, Khan and Knowles 2007).The posterolateral approach involves division of the piriformis, obturator internus, and gemelli tendons (Pellicci et al. 1998). This approach is considered to have less effect on gait since the abductor muscles are not dissected (Shaw 1991, Hedlundh et al. 1995), but it has been associated with an increased risk of dislocations, with risk of injury to the sciatic nerve. More recent studies have shown that use of larger femoral head sizes can markedly reduce the dislocation rate (Amlie et al. 2010, Bistolfi et al. 2011, Ho et al. 2012).We compared the different approaches with regard to patient satisfaction, pain, function, and HRQoL after primary THA.     

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.     

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.     

The final follow-up plain radiograph is sufficient for clinical evaluation of polyethylene wear in total hip arthroplasty: A study of validity and reliability

Background and purpose

Radiostereometric analysis (RSA) is a highly accurate tool for assessment of polyethylene (PE) wear in total hip arthroplasty (THA); however, PE wear measurements in clinical studies are often limited to plain radiographs. We evaluated the agreement between PE wear measured with PolyWare software, which uses plain radiographs, and by model-based RSA, which uses stereo radiographs.

Methods

Measurements of PE wear postoperatively and at final follow-up (after mean 6 years) on plain radiographs of 12 patients after cementless THA were evaluated with PolyWare software and the results were compared with those from RSA as the gold standard (Model-based RSA using elementary geometrical shape models; EGS-RSA). With PolyWare, we either used the final radiographic follow-up (PW1) only or both the postoperative follow-up and the final follow-up (PW2).

Results

The 2D mean wear measured (in mm) was 0.80, 1.07, and 0.60 for the PW2, PW1, and RSA method. 2D intra-method repeatability was similar for PW1 and RSA with limits of agreement (LOAs, in mm) of ± 0.22, and ± 0.23, respectively. 2D inter-method concurrent validity was best between PW1 and EGS-RSA with LOAs of ± 0.55. For 2D linear wear measurements, the PW1 method had a clinical repeatability similar to that of RSA.

Interpretation

PW1 is sufficient for retrospective determination of 2D wear from medium-term wear measurements above 0.5 mm, It alleviates the need for baseline plain radiographs, has a clinical precision similar to that of RSA, and is easy and inexpensive to use.Wear of polyethylene (PE) components is widely regarded as the main factor limiting longevity of total hip arthroplasty (THA) (Cooper et al. 1992). Clinical studies have shown that periprosthetic osteolysis and aseptic loosening is strongly related to wear rates of above 0.2 mm/year (Sochart 1999, Dowd et al. 2000).Radiostereometric analysis (RSA) is the most accurate tool for in vivo assessment of PE wear (Kärrholm et al. 1997, von Schewelov et al. 2004, Bragdon et al. 2006), and it is regarded as the gold standard (Ilchmann et al. 1995). However, many radiographic in vivo studies of PE wear in THA are restricted to measurements on plain radiographs because the RSA set-up is expensive and not widely available. Measurement of PE wear on plain radiographs is often limited to 2D analysis because poor quality of cross-table lateral radiographs is a common problem (Sychterz et al. 1999b, 2001). Although PE wear is known to occur multidirectionally (Yamaguchi et al. 1997, Akisue et al. 1999), the bulk of the wear is detectable on the anterior-posterior radiographs alone (Sychterz et al. 1997, Hui et al. 2003, Martell et al. 2003). Based on the availability of radiographs and investigator preferences, some authors favor analysis of serial radiographs (Sychterz et al. 1997, Kim et al. 2001, Hernigou and Bahrami 2003) to describe the pattern of wear and the steady-state wear (Sychterz et al. 1999a, Bragdon et al. 2006), whereas others use 2 radiographic follow-ups (postoperative and latest) (Kraay et al. 2006), or only the latest radiographic follow-up with the assumption of zero wear at baseline (Norton et al. 2002)Little is known about the conformity between PE wear results measured with RSA and computerized methods using plain radiographs (Ilchmann et al. 1995, von Schewelov et al. 2004, Bragdon et al. 2006). Our group has questioned the conformity of 2D PE wear measurements based on serial, 2, or 1 radiographic follow-up (Stilling et al. 2009b). We determined that there was a statistically significant difference between all approaches, but we were unable to determine which strategy best reflected the true extent of wear (Stilling et al. 2009b). In addition, we recently showed that model-based RSA is an accurate tool for measurement of PE wear in good agreement with the true wear (Stilling 2009).We have now studied the intra-method repeatability and concurrent validity between 2 methods (PolyWare and EGS-RSA) for measurement of PE wear in THA, in a group of patients with an average follow-up of 6 years. We wanted to determine (1) whether there would be a difference in repeatability between the methods, (2) whether there would be a difference in wear measured using 1 or 2 radiographic follow-ups with the PolyWare method, and (3) whether either of the 2 PolyWare measurement strategies (1 or 2 radiographic follow-ups) would give results similar to the wear measured by RSA (concurrent validity).     

Prognostic factors in lumbar spinal stenosis surgery: A prospective study of imaging- and patient-related factors in 109 patients who were operated on by decompression

Background and purpose

A considerable number of patients who undergo surgery for spinal stenosis have residual symptoms and inferior function and health-related quality of life after surgery. There have been few studies on factors that may predict outcome. We tried to find predictors of outcome in surgery for spinal stenosis using patient- and imaging-related factors.

Patients and methods

109 patients in the Swedish Spine Register with central spinal stenosis that were operated on by decompression without fusion were prospectively followed up 1 year after surgery. Clinical outcome scores included the EQ-5D, the Oswestry disability index, self-estimated walking distance, and leg and back pain levels (VAS). Central dural sac area, number of levels with stenosis, and spondylolisthesis were included in the MRI analysis. Multivariable analyses were performed to search for correlation between patient-related and imaging factors and clinical outcome at 1-year follow-up.

Results

Several factors predicted outcome statistically significantly. Duration of leg pain exceeding 2 years predicted inferior outcome in terms of leg and back pain, function, and HRLQoL. Regular and intermittent preoperative users of analgesics had higher levels of back pain at follow-up than those not using analgesics. Low preoperative function predicted low function and dissatisfaction at follow-up. Low preoperative EQ-5D scores predicted a high degree of leg and back pain. Narrow dural sac area predicted more gains in terms of back pain at follow-up and lower absolute leg pain.

Interpretation

Multiple factors predict outcome in spinal stenosis surgery, most importantly duration of symptoms and preoperative function. Some of these are modifiable and can be targeted. Our findings can be used in the preoperative patient information and aid the surgeon and the patient in a shared decision making process.Decompressive surgery for lumbar spinal stenosis is the most frequently performed spine operation in many countries (Weinstein et al. 2006, Strömqvist et al. 2009). However, one third of patients are not satisfied with the outcome because of residual leg and back pain, inferior function, and poor health-related quality of life (Katz et al. 1995, Airaksinen et al. 1997, Jönsson et al. 1997, Jansson et al. 2009, Strömqvist et al. 2009, Hara et al. 2010).2 recent randomized studies have shown surgery to be superior to nonoperative treatment in lumbar spinal stenosis (Malmivaara et al. 2007, Weinstein et al. 2008), but many patients improve without surgical treatment (Malmivaara et al. 2007). The question remains as to who benefits most from surgery. Identification of prognostic factors that can aid in selection of patients for surgery is therefore important. Prognostic factors in lumbar spinal stenosis surgery have been studied, but they are not well defined (Turner et al. 1992, Aalto et al. 2006). Aalto et al. (2006) reviewed studies of lumbar spinal stenosis surgery and found that only 21 studies of 885 were of sufficient quality to merit identification of prognostic factors. The main reason for exclusion was a retrospective study design and a limited number of predictors. Cardiovascular and overall comorbidity, disorders influencing walking ability, self-rated health, income, severity of central stenosis, and severity of scoliosis were found to be predictors of outcome, but no single study could identify more than one of these predictors. More recently, smoking, depression, psychiatric illness, and high body mass index have been found to be predictive of negative outcome, as have long duration of symptoms and preoperative resting numbness (Ng et al. 2007, Hara et al. 2010, Athiviraham et al. 2011, Radcliff et al. 2011, Sandén et al. 2011, Sinikallio et al. 2011).Cross-sectional imaging (most often MRI) has an important role in confirming the diagnosis of spinal stenosis, and is essential for surgical planning. Even so, the prognostic value of the narrowness of the dural sac area is not well established (Jönsson et al 1997, Amundsen et al. 2000, Yukawa et al. 2002). Studies incorporating both imaging and patient-related factors in a systematic way have been exceedingly rare (Amundsen et al. 2000, Yukawa et al. 2002).We used patient data from the Swedish Spine Register protocol (Strömqvist et al. 2009) and MRI measurements of central dural sac area, multilevel stenosis, and spondylolisthesis to find predictors of outcome in terms of function, HRLQoL, and leg and back pain after decompression for lumbar spinal stenosis.     

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.     

Persistent pain is common 1–2 years after shoulder replacement: A nationwide registry-based questionnaire study of 538 patients

Results 538 patients were available for analysis. The prevalence of persistent pain was 22% (CI: 18–25), and the prevalence of presumed neuropathic pain was 13% (CI: 10–16). Persistent pain was more frequent in fracture patients (29%) than in osteoarthritis patients (16%), while the prevalence of neuropathic pain was similar. Severe pain during the first postoperative week increased the risk of persistent pain. Risk also increased with hemiprosthesis (as compared to total prosthesis) in osteoarthritis patients, and with previous osteosynthesis and pain elsewhere in fracture patients.Interpretation Persistent pain after shoulder replacement is a daily burden for many patients. Further studies should address patient and prosthesis selection, postoperative pain management, and follow-up of these patients.There is a substantial amount of literature documenting that there is a possible risk of persistent pain after almost any surgical procedure (Macrae 2001, Johansen et al. 2012). The prevalence rates are highly dependent on the type of surgery, and vary from 5% to 85% (Kehlet et al. 2006, Macrae 2008). The consequences of chronic or persistent postsurgical pain are significant, not only in terms of suffering and reduced quality of life for the individual patient, but also with regard to the subsequent costs to healthcare services and social services. Many authors have reported putative risk factors for persistent pain, including genetic factors, age, psychosocial factors, type of anesthesia, pain elsewhere than the surgical site, other comorbidities, preoperative pain, and acute postoperative pain (Althaus et al. 2012, VanDenKerkhof et al. 2013). Intraoperative nerve damage and the extent of surgery are also important risk factors (Katz and Seltzer 2009). In fact, many patients with persistent postsurgical pain present with characteristic symptoms of neuropathic pain in the affected area (Kehlet et al. 2006).There is a scarcity of data on persistent postsurgical pain after orthopedic surgery. To our knowledge, previous studies focusing on persistent postsurgical pain in orthopedic patients have concerned mainly amputation or hip or knee replacement (Nikolajsen et al. 2006, Lundblad et al. 2008, Beswick et al. 2012, Liu et al. 2012, Jansen et al. 2014). Trials of shoulder replacement surgery have more commonly reported pain relief, or a composite score including pain, rather than the prevalence of pain at follow-up. There has been very little research on predictive factors for persistent postsurgical pain following shoulder replacement, but the general outcome has been shown to be associated with diagnosis and prosthesis type (Radnay et al. 2007, Fevang et al. 2013) and with previous shoulder surgery, age, and preoperative Short Form-36 mental score and DASH functional score (Simmen et al. 2008). Identification of subgroups at increased risk is important in order to establish interventions to prevent or minimize the impact of persistent postsurgical pain.We investigated the prevalence of, the characteristics of, and risk factors for persistent pain 1–2 years after more than 500 shoulder replacements performed in Denmark.     

Intraarticular location predicts cartilage filling and subchondral bone changes in a chondral defect

Background and purpose

The natural history of, and predictive factors for outcome of cartilage restoration in chondral defects are poorly understood. We investigated the natural history of cartilage filling subchondral bone changes, comparing defects at two locations in the rabbit knee.

Animals and methods

In New Zealand rabbits aged 22 weeks, a 4-mm pure chondral defect (ICRS grade 3b) was created in the patella of one knee and in the medial femoral condyle of the other. A stereo microscope was used to optimize the preparation of the defects. The animals were killed 12, 24, and 36 weeks after surgery. Defect filling and the density of subchondral mineralized tissue was estimated using Analysis Pro software on micrographed histological sections.

Results

The mean filling of the patellar defects was more than twice that of the medial femoral condylar defects at 24 and 36 weeks of follow-up. There was a statistically significant increase in filling from 24 to 36 weeks after surgery at both locations.The density of subchondral mineralized tissue beneath the defects subsided with time in the patellas, in contrast to the density in the medial femoral condyles, which remained unchanged.

Interpretation

The intraarticular location is a predictive factor for spontaneous filling and subchondral bone changes of chondral defects corresponding to ICRS grade 3b. Disregarding location, the spontaneous filling increased with long-term follow-up. This should be considered when evaluating aspects of cartilage restoration.Focal articular cartilage injuries of the knee are common (Hjelle et al. 2002, Aroen et al. 2004) and they can impair patients'' quality of life as much as severe osteoarthritis (Heir et al. 2010). The literature concerning the natural history of focal cartilage defects in patients, and the intrinsic factors affecting it, is limited (Linden 1977, Messner and Gillquist 1996, Drogset and Grontvedt 2002, Shelbourne et al. 2003, Loken et al. 2010). In experimental studies evaluating cartilage restoration in general, the importance of intrinsic factors such as the depth and size of the lesion and the time from when the lesion was made to evaluation have been emphasized (Shapiro et al. 1993, Hunziker 1999, Lietman et al. 2002). Which part of the joint is affected and whether or not the defect is weight-bearing are also of interest (Hurtig 1988, Frisbie et al. 1999). Most of these studies have, however, concerned defects penetrating the subchondral mineralized tissues corresponding to ICRS grade 4 (Brittberg and Winalski 2003). Access to bone marrow elements in these defects might be one of the strongest predictive factors for filling of the defect, making the importance of other factors difficult to evaluate (Hunziker 1999).In experimental studies on pure chondral defects that do not penetrate the subchondral mineralized tissues, corresponding to ICRS grade 3b (Brittberg and Winalski 2003), the type of animal studied, the size of the lesion, and the location of the defects vary, and there is limited data on the influence of these parameters on outcome (Breinan et al. 2000). The information on spontaneous filling comes mainly from observations of untreated defects serving as controls (Grande et al. 1989, Brittberg et al. 1996, Breinan et al. 1997, 2000, Frisbie et al. 1999, 2003, Dorotka et al. 2005) and the information on subchondral bone changes is even more limited (Breinan et al. 1997, Frisbie et al. 1999). Although most human focal cartilage lesions are located on the medial femur condyle (Aroen et al. 2004), there have been few experimental studies involving untreated ICRS grade 3b defects on the medial femur condyle (Dorotka et al. 2005). According to a PubMed search, the rabbit knee is the most widely used experimental animal model for cartilage restoration (Årøen 2005). The locations of ICRS grade 3 chondral defects in the rabbit knee evaluated for spontaneous changes have included the patella (Grande et al. 1989, Brittberg et al. 1996) and, in one study, defects at the distal surface of the femur (Mitchell and Shepard 1976). The latter report did not, however, include quantitative data.To our knowledge, the influence of the intraarticular location on the outcome of cartilage restoration and subchondral bone changes has not been thoroughly studied. Thus, the main purpose of our study was to test the hypothesis that the intraarticular location influences the spontaneous filling of a chondral defect that does not penetrate the subchondral bone. Secondly, we wanted to evaluate whether the intraarticular location would influence changes in the subchondral bone and degenerative changes as evaluated from macroscopic appearance and proteoglycan content of synovial fluid (Messner et al. 1993a).     

Increased risk of revision of cementless stemmed total hip arthroplasty with metal-on-metal bearings: Data from the Nordic Arthroplasty Register Association

Background and purpose

Data from the national joint registries in Australia and England and Wales have revealed inferior medium-term survivorship for metal-on-metal (MoM) total hip arthroplasty (THA) than for metal-on-polyethylene (MoP) THA. Based on data from the Nordic Arthroplasty Register Association (NARA), we compared the revision risk of cementless stemmed THA with MoM and MoP bearings and we also compared MoM THA to each other.

Patients and methods

We identified 32,678 patients who were operated from 2002 through 2010 with cementless stemmed THA with either MoM bearings (11,567 patients, 35%) or MoP bearings (21,111 patients, 65%). The patients were followed until revision, death, emigration, or the end of the study period (December 31, 2011), and median follow-up was 3.6 (interquartile range (IQR): 2.4–4.8) years for MoM bearings and 3.4 (IQR: 2.0–5.8) years for MoP bearings. Multivariable regression in the presence of competing risk of death was used to assess the relative risk (RR) of revision for any reason (with 95% confidence interval (CI)).

Results

The cumulative incidence of revision at 8 years of follow-up was 7.0% (CI: 6.0–8.1) for MoM bearings and 5.1% (CI: 4.7–5.6) for MoP bearings. At 6 years of follow-up, the RR of revision for any reason was 1.5 (CI: 1.3–1.7) for MoM bearings compared to MoP bearings. The RR of revision for any reason was higher for the ASR (adjusted RR = 6.4, CI: 5.0–8.1), the Conserve Plus (adjusted RR = 1.7, CI: 1.1–2.5) and “other” acetabular components (adjusted RR = 2.4, CI: 1.5–3.9) than for MoP THA at 6 years of follow-up.

Interpretation

At medium-term follow-up, the survivorship for cementless stemmed MoM THA was inferior to that for MoP THA, and metal-related problems may cause higher revision rates for MoM bearings with longer follow-up.Wear particles from the polyethylene liner in metal-on-polyethylene (MoP) bearings in total hip arthroplasty (THA) are associated with osteolysis and aseptic loosening of the implant (Jacobs et al. 1994). Surgeons therefore became interested in alternatives such as metal-on-metal (MoM) bearings. The main justification for using large-diameter-head (LDH) MoM bearings in THA was less wear and the hope of lower revision rates. However, a lower risk of revision has only been found for revision due to dislocation (Kostensalo et al. 2013), whereas the total risk of revision has been found to be increased in some studies (Smith et al. 2012, Huang et al. 2013). In addition, LDH MoM was introduced in order to achieve increased range of motion and better function (Burroughs et al. 2005, Davis et al. 2007), but that has not been shown clinically (Penny et al. 2013).Several concerns about the use of MoM bearings in hip surgery have been voiced in recent years: excessive failure rates for certain brands and implant combinations used with MoM components have been reported (Langton et al. 2011, Australian Orthopaedic Association 2013). Some designs are associated with increased frequency of aseptic loosening (Australian Orthopaedic Association 2013), and large head sizes placed on conventional stems may cause taper junction failure (Langton et al. 2012). Exposure to chromium and cobalt may cause adverse reactions to metal debris (ARMD) (Langton et al. 2010) such as pseudotumors (Pandit et al. 2008) and hypersensivity reactions (Willert et al. 2005) locally in the hip joint. Furthermore, metal ions may be genotoxic (Daley et al. 2004).Only a few population-based studies on MoM bearings in stemmed THAs from hip arthroplasty registries have been published (Smith et al. 2012, Mokka et al. 2013b, Furnes et al. 2014), with only 1 population-based study focusing on causes of revision resulting from specific combinations of acetabular and femoral components (Mokka et al. 2013b). We compared the 6-year revision risk for MoM bearings with that for MoP bearings in cementless stemmed THA. In addition, we studied different designs of stemmed MoM THAs and the causes of revision in a population-based follow-up study using data from the Nordic Arthroplasty Register Association (NARA).     

Increasing incidence of hip arthroplasty for primary osteoarthritis in 30- to 59-year-old patients

Background and purpose

The use of hip arthroplasties is evidently increasing, but there are few published data on the incidence in young patients.

Methods

We used data on total and resurfacing hip arthroplasties (THAs and RHAs) from the Finnish Arthroplasty Register and population data from Statistics Finland to analyze the incidences of THA and RHA in patients aged 30–59 years in Finland, for the period 1980 through 2007.

Results

The combined incidences of THAs and RHAs among 30- to 59-year-old inhabitants increased from 9.5 per 10⁵ inhabitants in 1980 to 61 per 10⁵ inhabitants in 2007. Initially, the incidence of THA was higher in women than men, but since the mid-90s the incidences were similar. The incidence increased in all age groups studied (30–39, 40–49, and 50–59 years) but the increase was 6-fold and 36-fold higher in the latter two groups than in the first. The incidence of THA was constant; the increased incidence of overall hip arthroplasty was due to the increasing number of RHAs performed.

Interpretation

We have found a steady increase in the incidence of hip arthroplasty in patients with primary hip osteoarthritis in Finland, with an accelerating trend in the past decade, due to an increase in the incidence of RHA. As the incidence of hip osteoarthritis has not increased, the indications for hip arthroplasty appear to have become broader.75% of THAs are performed on elderly patients for painful osteoarthritis (OA); in younger patients (under 50–60 years), the proportion of OA diminishes to 42–54%. Most patients are women (Lucht 2000, Furnes et al. 2001, Puolakka et al. 2001, Malchau et al. 2002).Several authors have reported an increasing incidence of treatment of OA with THA (Birrell et al. 1999, Ostendorf et al. 2002, Wells et al. 2002, Merx et al. 2003, Kurtz et al. 2005, 2007), but only a few authors have reported the incidences for younger patients separately (Birrell et al. 1999, Ingvarsson et al. 1999). Resurfacing hip arthroplasty (RHA) is an option marketed for younger patients, though its value is still uncertain (McGrory et al. 2009).We examined the changes in incidence of primary THA and RHA in young patients with OA in Finland between the years 1980 and 2007.     

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.     

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.     

Early subsidence of shape-closed hip arthroplasty stems is associated with late revision: A systematic review and meta-analysis of 24 RSA studies and 56 survival studies

Background and purpose

Few studies have addressed the association between early migration of femoral stems and late aseptic revision in total hip arthroplasty. We performed a meta-regression analysis on 2 parallel systematic reviews and meta-analyses to determine the association between early migration and late aseptic revision of femoral stems.

Patients and methods

Of the 2 reviews, one covered early migration data obtained from radiostereometric analysis (RSA) studies and the other covered long-term aseptic revision rates obtained from survival studies with endpoint revision for aseptic loosening. Stems were stratified according to the design concept: cemented shape-closed, cemented force-closed, and uncemented. A weighted regression model was used to assess the association between early migration and late aseptic revision, and to correct for confounders. Thresholds for acceptable and unacceptable migration were determined in accordance with the national joint registries (≤ 5% revision at 10 years) and the NICE criteria (≤ 10% revision at 10 years).

Results

24 studies (731 stems) were included in the RSA review and 56 studies (20,599 stems) were included in the survival analysis review. Combining both reviews for the 3 design concepts showed that for every 0.1-mm increase in 2-year subsidence, as measured with RSA, there was a 4% increase in revision rate for the shape-closed stem designs. This association remained after correction for age, sex, diagnosis, hospital type, continent, and study quality. The threshold for acceptable migration of shape-closed designs was defined at 0.15 mm; stems subsiding less than 0.15 mm in 2 years had revision rates of less than 5% at 10 years, while stems exceeding 0.15 mm subsidence had revision rates of more than 5%.

Interpretation

There was a clinically relevant association between early subsidence of shape-closed femoral stems and late revision for aseptic loosening. This association can be used to assess the safety of shape-closed stem designs. The published research is not sufficient to allow us to make any conclusions regarding such an association for the force-closed and uncemented stems.Over 1 million total hip arthroplasties (THAs) are performed every year worldwide, and this number is expected to double within the next 2 decades (Pivec et al. 2012). The design and method of fixation of a THA determines the stability of the implant, and these are therefore crucial factors for achievement of long-term survival. However, most of the new THA designs have been introduced onto the market without demonstrating good performance (Sheth et al. 2009). This has led to several THAs having high failure rates, such as the Charnley Elite Plus (Hauptfleisch et al. 2006). To prevent future disasters with orthopedic implants, several countries have developed guidelines to guarantee patient safety, e.g. the NICE guidelines (NHS). Furthermore, it has become increasingly evident that a phased evidence-based introduction, as is common with pharmaceuticals, is necessary to regulate the introduction of new THA designs to the market (Malchau 2000, McCulloch et al. 2009, Schemitsch et al. 2010). This should include systematic assessment and early detection of aseptic loosening in small groups of patients.Although it may take as long as 10 years for aseptic loosening of implants to become manifest, it is possible to detect the loosening process as early as 1–2 years postoperatively, using radiostereometric analysis (RSA). Since RSA allows in vivo, 3D measurement of the migration of THAs with an accuracy of 0.2 mm for translations and 0.5 degrees for rotations, only a small number of patients is needed to compare a new innovative design to a gold-standard design (Grewal et al. 1992, Karrholm et al. 1994, Ryd et al. 1995, Thanner et al. 1995, Hauptfleisch et al. 2006, Nieuwenhuijse et al. 2012). Thus, only a few patients will have been exposed if that design turns out to be a poor one. RSA could therefore play an important role in phased evidence-based market introduction of new THA designs (Faro and Huiskes 1992, Bulstrode et al. 1993, Malchau 1995, 2000, Nelissen et al. 2011).Following on from our 2 earlier studies on the association between early migration and late aseptic revision of tibial components and acetabular cups, this systematic review and meta-analysis focused on the femoral stem (Pijls et al. 2012a, b). We hypothesized that early migration, as measured with RSA, is associated with late revision for aseptic loosening. We systematically reviewed the association between early migration and late revision for aseptic loosening of the femoral stem in primary THA. This could eventually lead to clinical guidelines, to be used in a phased introduction of new THA designs.