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.     

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.     

Single periarticular local infiltration analgesia reduces opiate consumption until 48 hours after total knee arthroplasty: A randomized placebo-controlled trial involving 56 patients

Background —

Randomized trials evaluating efficacy of local infiltration analgesia (LIA) have been published but many of these lack standardized analgesics. There is a paucity of reports on the effects of LIA on functional capability and quality of life.

Methods —

56 patients undergoing unilateral total knee arthroplasty (TKA) were randomized into 2 groups in this placebo-controlled study with 12-month follow-up. In the LIA group, a mixture of levobupivacaine (150 mg), ketorolac (30 mg), and adrenaline (0.5 mg) was infiltrated periarticularly. In the placebo group, infiltration contained saline. 4 different patient-reported outcome measures (PROMs) were used for evaluation of functional outcome and quality of life.

Results —

During the first 48 hours postoperatively, patients in the LIA group used less oxycodone than patients in the placebo group in both cumulative and time-interval follow-up. The effect was most significant during the first 6 postoperative hours. The PROMs were similar between the groups during the 1-year follow-up.

Interpretation —

Single periarticular infiltration reduced the amount of oxycodone used and enabled adequate pain management in conjunction with standardized peroral medication without adverse effects. No clinically marked effects on the functional outcome after TKA were detected.The goal of local infiltration analgesia (LIA) after TKA is to provide simple, effective, and safe pain relief during the first postoperative days, with reduced opiate consumption (Kerr and Kohan 2008). Adequate postoperative pain control is usually achieved using multimodal pain management, but it continues to be a challenge in many TKA patients. The recommended intraoperative anesthetic technique during TKA is either general anesthesia combined with femoral nerve block or spinal anesthesia combined with morphine (Fischer et al. 2008). Femoral nerve block is effective in reducing pain, but may cause falls after TKA (Ilfeld et al. 2010). Opiates, although effective in reducing pain, have severe side effects (nausea, itching, reduced gut mobility, and urinary retention), which may markedly retard the postoperative recovery. Thus, in addition to providing better pain relief, multimodal analgesia is aimed at reducing the amount of opiates used.Several techniques of infiltration analgesia have been published, with enhanced pain relief for up to 48 hours (Kehlet and Andersen 2011). With longer follow-up time, the perioperatively administered LIA loses its efficacy (Essving et al. 2010). Furthermore, intra-articular LIA and extra-articular LIA have been reported to be equally effective in reducing postoperative pain (Andersen et al. 2008b). The benefit of using an intra-articular catheter has been questioned by some authors—concerning both the effectiveness of pain treatment and the theoretical increased risk of infection (Busch et al. 2006, Mullaji et al. 2010).A recently published review divided LIA techniques into 2 groups—single administration and multiple administration—and it also compared different local infiltration techniques (Gibbs et al. 2012). Many studies included in that review were poorly controlled, with no standardization of oral analgesics. In the group of multiple administration methods, the reduction of opiate consumption was comparable to the results for the single administration group. Based on these findings, the authors of the review recommended the use of a single, intraoperative and systematic infiltration cocktail of high-dose ropivacaine, adrenaline, and ketorolac to all exposed tissues. Another review highlighted poor documentation of the long-term effect of LIA on knee function and quality of life (Ganapathy et al. 2011).We studied the effects of a single, intraoperative periarticular infiltration on postoperative pain management after TKA.     

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.     

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.     

What is the optimal alignment of the tibial and femoral components in knee arthroplasty?: An overview of the literature

Background

Surgeon-dependent factors such as optimal implant alignment are thought to play a significant role in outcome following primary total knee arthroplasty (TKA). Exact definitions and references for optimal alignment are, however, still being debated. This overview of the literature describes different definitions of component alignment following primary TKA for (1) tibiofemoral alignment in the AP plane, (2) tibial and femoral component placement in the AP plane, (3) tibial and femoral component placement in the sagittal plane, and (4) rotational alignment of tibial and femoral components and their role in outcome and implant survival.

Methods

We performed a literature search for original and review articles on implant positioning following primary TKA. Definitions for coronal, sagittal, and rotational placement of femoral and tibial components were summarized and the influence of positioning on survival and functional outcome was considered.

Results

Many definitions exist when evaluating placement of femoral and tibial components. Implant alignment plays a role in both survival and functional outcome following primary TKA, as component malalignment can lead to increased failure rates, maltracking, and knee pain.

Interpretation

Based on currently available evidence, surgeons should aim for optimal alignment of tibial and femoral components when performing TKA.Total knee arthroplasty (TKA) is one of the most frequently performed orthopedic procedures, with an estimated 700,000 primary TKAs performed annually in the USA alone (National Hospital Discharge Survey 2010). While survival of primary TKAs is excellent, as most registries report 10-year survival of close to 95% for most implants (Graves et al. 2013, NJR 2013), recent studies have indicated that patient satisfaction is substantially worse. Up to 20% of the patients are not satisfied with the outcome as assessed 1 year postoperatively (Bourne et al. 2010, Klit et al. 2014) and a recent review found that 10–34% of patients had pain 3 months to 5 years after TKA (Beswick et al. 2012). Although patient-related factors (such as age, preoperative OKS and EQ5D, comorbidities, general health, depression, anxiety, and ASA) have been found to influence patient-reported outcome the most, surgical factors such as implant brand, hospital type (Baker et al. 2012), and implant alignment are also important (Choong et al. 2009, Longstaff et al. 2009).Implant malalignment following primary TKA has been reported to be the primary reason for revision in 7% of revised TKAs (Schroer et al. 2013) and it has been linked to both decreased implant survival (Ritter et al. 2011) and inferior patient-reported outcomes (Choong et al. 2009, Longstaff et al. 2009). However, optimal alignment still remains a matter of controversy, as several recent reports have found little or no correlation between postoperative tibiofemoral malalignment in the coronal plane and revision rates (Morgan et al. 2008, Parratte et al. 2010, Bonner et al. 2011). The emergence of computer navigation (Fu et al. 2012) and patient-specific cutting blocks (Lachiewicz and Henderson 2013)—with the proposed benefits of improved component positioning and fewer outliers—have further fueled this debate, as benefits in survival and patient related outcome are not apparent. Also, kinematic alignment (as opposed to mechanical alignment) in TKA has been debated in recent years as inherently, it does not adhere to traditional thinking concerning implant positioning and it is intended to improve postoperative outcome (Howell et al. 2013a).We investigated whether the literature supports definitions of optimal alignment following primary TKA surgery and whether a correlation between malalignment and inferior outcome could be identified. The following parameters were investigated separately: (1) tibiofemoral alignment in the AP plane; (2) tibial and femoral component placement in the AP plane; (3) tibial and femoral component placement in the sagittal plane; and (4) rotational alignment of tibial and femoral components.     

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).     

Intraarticular vs. extraarticular ropivacaine infusion following high-dose local infiltration analgesia after total knee arthroplasty: a randomized double-blind study

Background and purpose

Ropivacaine infusion following high-volume local infiltration analgesia has been shown to be effective after total knee arthroplasty, but the optimum site of administration of ropivacaine has not been evaluated. We compared the effects of intraarticular and extraarticular adminstration of the local anesthetic for postoperative supplementation of high-volume local infiltration analgesia.

Patients and methods

In this double-blind study, 36 rheumatic patients aged 51–78 years with physical status ASA 2–3 who were scheduled for total knee arthroplasty were randomized into 2 groups. All patients received wound infiltration at the end of surgery with 300 mg ropivacaine, 30 mg ketorolac, and 0.5 mg epinephrine (total volume 156 mL). A tunneled catheter was randomly placed either extraarticularly or intraarticularly. Continuous infusion of ropivacain (0.5%, 2 mL/h) was started immediately and was maintained during the next 48 h. Pain intensity at rest, on movement, and with mobilization was estimated by the patients and the physiotherapist; rescue morphine consumption was recorded.

Results

As estimated by the patients, ropivacaine administered intraarticularly did not improve analgesia relative to extraarticular infusion, but improved the first mobilization. The incidence of high intensity of pain (VAS 7–10) was less in the group with intraarticular infusion. Analgesic requirements were similar in the 2 groups (47 mg and 49 mg morphine). No complications of postoperative wound healing were seen and there were no toxic side effects.

Interpretation

Continuous infusion of ropivacaine intraarticulary did not improve postoperative analgesia at rest relative to extraarticular administration, but it appeared to reduce the incidence of high pain intensity during first exercises, and could therefore be expected to improve mobilization up to 24 h after total knee arthroplasty.Pain after total knee arthroplasty is severe in two-thirds of patients (Bonica 1984, Beattie et al. 1997). The pain may be a result of trauma to the bone or soft tissues or a result of hyperperfusion after tourniquet release (Estebe et al. 1995). The optimal form of pain relief is one that is applied preoperatively, perioperatively, and postoperatively to avoid the establishment of pain hypersensitivity (Badner et al. 1996). Good pain relief allows effective postoperative rehabilitation (Shoji et al. 1990). In contrast to epidural analgesia and femoral block, an alternative method to achieve good postoperative pain relief is local infiltration combined with single-shot injection or continuous infusion of local anesthetics into the surgical site. Local anesthetic infiltration is helpful in the management of postoperative pain after several orthopedic procedures (De Andres et al. 1993). The use of intraarticular analgesia to limit postoperative pain following knee arthroplasty has been investigated, with different results (Smith et al. 1991, Allen et al. 1993, Osborne and Keene 1993, Badner et al. 1996, Mauerhan et al. 1997, Ritter et al. 1999).A local infiltration analgesia (LIA) technique was developed by Kerr and Kohan in Sydney, Australia (Rostlund and Kehlet 2007, Kerr and Kohan 2008). With this technique, the long-acting local anesthetic ropivacaine, a non-steroidal anti-inflammatory drug (ketorolac), and epinephrine are infiltrated periarticulary during surgery. An alternative technique that might have widespread applicability is the insertion of catheters to allow continuous infusion of local anesthetics into the surgical wound at the end of the procedure. There is a need for detailed systematic studies to evaluate the optimal site of administration of local anaesthetics. In this randomized, double-blind study, we compared the analgesic effects of continuous infusion of local anesthetics either intraarticulary or extraarticulary after TKA using the LIA technique.     

A randomized, controlled trial comparing local infiltration analgesia with epidural infusion for total knee arthroplasty

Background

There have been few studies describing wound infiltration with additional intraarticular administration of multimodal analgesia for total knee arthroplasty (TKA). In this study, we assessed the efficacy of wound infiltration combined with intraarticular regional analgesia with epidural infusion on analgesic requirements and postoperative pain after TKA.

Methods

40 consecutive patients undergoing elective, primary TKA were randomized into 2 groups to receive either (1) intraoperative wound infiltration with 150 mL ropivacaine (2 mg/mL), 1 mL ketorolac (30 mg/mL), and 0.5 mL epinephrine (1 mg/mL) (total volume 152 mL) combined with intraarticular infusion (4 mL/h) of 190 mL ropivacaine (2 mg/mL) plus 2 mL ketorolac (30 mg/mL) (group A), or (2) epidural infusion (4 mL/h) of 192 mL ropivacaine (2 mg/mL) combined with 6 intravenous administrations of 0.5 mL ketorolac (30 mg/mL) for 48 h postoperatively (group E). For rescue analgesia, intravenous patient-controlled-analgesia (PCA) morphine was used.Morphine consumption, intensity of knee pain (0–100 mm visual analog scale), and side effects were recorded. Length of stay and corrected length of stay were also recorded (the day-patients fulfilled discharge criteria).

Results

The median cumulated morphine consumption, pain scores at rest, and pain scores during mobilization were reduced in group A compared to group E. Corrected length of stay was reduced by 25% in group A compared to group E.

Interpretation

Peri- and intraarticular analgesia with multimodal drugs provided superior pain relief and reduced morphine consumption compared with continuous epidural infusion with ropivacaine combined with intravenous ketorolac after TKA.Total knee arthroplasty (TKA) usually results in severe postoperative pain. Continuous epidural infusion with a local anesthetic is a standard regime for postoperative analgesia after TKA. Epidural analgesia and also peripheral nerve block analgesia have been shown to reduce opioid consumption compared with intravenous patient-controlled analgesia (PCA). Even though both modalities reduce the occurrence of the well-known side effects of opioid drugs, they involve extra equipment and are associated with substantial side effects (Choi et al. 2003, Davies et al. 2004, Boezaart 2006). Wound infiltration with multimodal analgesia has been a controversial issue for many years (Dahl et al. 1994). Different modes of perioperative analgesia either without or combined with intraarticular infusion or bolus injection(s) for both TKA and total hip arthroplasty have been described (Bianconi et al. 2003, Rasmussen et al. 2004, Reilly et al. 2005, Andersen et al. 2007a, b). Only a few studies have described high-volume peri- and intraarticular analgesia for TKA (Busch et al. 2006, Vendittoli et al. 2006, Toftdahl et al. 2007). The hypothesis in our trial was that wound infiltration and intraarticular infusion of ropivacaine and ketorolac would reduce opioid consumption during the active treatment period (0–48 h postoperatively) after TKA compared to epidural infusion of ropivacaine and intravenous ketorolac. Primary outcome was 48-h opioid use. Secondary outcomes included pain at rest and during mobilization, side effects, length of hospital stay (LOS), and corrected length of stay (the day-patients fulfilled discharge criteria).     

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.     

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.     

Dissatisfied patients after total knee arthroplasty: A registry study involving 114 patients with 8–13 years of follow-up

Background and purpose

In 2003, an enquiry by the Swedish Knee Arthroplasty Register (SKAR) 2–7 years after total knee arthroplasty (TKA) revealed patients who were dissatisfied with the outcome of their surgery but who had not been revised. 6 years later, we examined the dissatisfied patients in one Swedish county and a matched group of very satisfied patients.

Patients and methods

118 TKAs in 114 patients, all of whom had had their surgery between 1996 and 2001, were examined in 2009–2010. 55 patients (with 58 TKAs) had stated in 2003 that they were dissatisfied with their knees and 59 (with 60 TKAs) had stated that they were very satisfied with their knees. The patients were examined clinically and radiographically, and performed functional tests consisting of the 6-minute walk and chair-stand test. All the patients filled out a visual analog scale (VAS, 0–100 mm) regarding knee pain and also the Hospital and Anxiety and Depression scale (HAD).

Results

Mean VAS score for knee pain differed by 30 mm in favor of the very satisfied group (p < 0.001). 23 of the 55 patients in the dissatisfied group and 6 of 59 patients in the very satisfied group suffered from anxiety and/or depression (p = 0.001). Mean range of motion was 11 degrees better in the very satisfied group (p < 0.001). The groups were similar with regard to clinical examination, physical performance testing, and radiography.

Interpretation

The patients who reported poor response after TKA continued to be unhappy after 8–13 years, as demonstrated by VAS pain and HAD, despite the absence of a discernible objective reason for revision.The results of TKA are regarded as being favorable (Robertsson et al. 2000, Kane et al. 2005, Nilsdotter et al. 2009, Carr et al. 2012) with few surgical complications and a revision rate of less than 5% after 10 years (Vessely et al. 2006, Robertsson et al. 2010). Poor outcome after primary TKA, apart from the revision, is between 6% and 14% (Anderson et al. 1996, Hawker et al. 1998, Heck et al. 1998, Robertsson et al. 2000, Robertsson and Dunbar 2001, Brander et al. 2003, Noble et al. 2006, Fisher et al. 2007, Wylde et al. 2008, Kim et al. 2009, Bourne et al. 2010, Scott et al. 2010). The reason for poor outcome after TKA may be related to problems with the knee surgery itself, although it has been suggested that extra-articular causes such as hip disease, spine disorder, vascular disease, or reflex sympathetic dystrophy may contribute. Some studies have suggested that factors not primarily related to structural tissue changes, but of psychological nature instead, may be involved (Wylde et al. 2007, Rolfson et al. 2009).The Swedish Knee Arthroplasty Register (SKAR) registers primary arthroplasties performed in Sweden as well as revisions, and has been estimated to capture 97% of the surgeries performed (SKAR 2012). The SKAR sends questionnaires regarding satisfaction to patients who were operated on during certain time periods (Robertsson et al. 2000, and Dunbar 2001). We used the SKAR to identify patients who had not undergone revision surgery and who were dissatisfied with their outcome 2–7 years after TKA surgery. As a reference we chose an age-, sex-, date-of-surgery-, and hospital-matched control group of highly satisfied patients who were operated during the same period. Our aim was to assess the differences between these 2 patient groups.     

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.     

Uncemented femoral revision arthroplasty using a modular tapered,fluted titanium stem: 5- to 16-year results of 163 cases

Background and purpose —

Due to the relative lack of reports on the medium- to long-term clinical and radiographic results of modular femoral cementless revision, we conducted this study to evaluate the medium- to long-term results of uncemented femoral stem revisions using the modular MRP-TITAN stem with distal diaphyseal fixation in a consecutive patient series.

Patients and methods —

We retrospectively analyzed 163 femoral stem revisions performed between 1993 and 2001 with a mean follow-up of 10 (5–16) years. Clinical assessment included the Harris hip score (HHS) with reference to comorbidities and femoral defect sizes classified by Charnley and Paprosky. Intraoperative and postoperative complications were analyzed and the failure rate of the MRP stem for any reason was examined.

Results —

Mean HHS improved up to the last follow-up (37 (SD 24) vs. 79 (SD 19); p < 0.001). 99 cases (61%) had extensive bone defects (Paprosky IIB–III). Radiographic evaluation showed stable stem anchorage in 151 cases (93%) at the last follow-up. 10 implants (6%) failed for various reasons. Neither a breakage of a stem nor loosening of the morse taper junction was recorded. Kaplan-Meier survival analysis revealed a 10-year survival probability of 97% (95% CI: 95–100).

Interpretation —

This is one of the largest medium- to long-term analyses of cementless modular revision stems with distal diaphyseal anchorage. The modular MRP-TITAN was reliable, with a Kaplan-Meier survival probability of 97% at 10 years.Long-term outcome of femoral revision arthroplasty depends on proper restoration of joint mechanics by reconstructing the anatomic center of rotation in combination with fixation that provides long-term stability (Gravius et al. 2011).The published medium- to long-term survival rates of cemented revision THA are between 35% and 91% (Kavanagh and Fitzgerald 1985, Retpen et al. 1989, Stromberg and Herberts 1996, Weber et al. 1996). One stage cemented stem revision leads to increased bone loss (Rader and Eulert 2005) and is associated with a much higher rate of re-revision than cementless femoral stem revision (Dohmae et al. 1988). Cemented revision stems only appear to be advisable for less active patients with an average life expectancy of less than 10 years (Weiss et al. 2011). In comparison, uncemented revision hip arthroplasty gives medium- to long-term survival rates of 60–97% (Head et al. 2001, Engh et al. 2002, Kwong et al. 2003).Over the years, uncemented modular revision stems have become increasingly popular (Fink et al. 2009). In complex revision surgery, modular uncemented femoral implants may overcome the limitations of non-modular and mostly straight stems—for example, the difficulty in establishing femoral leg length, femoral anteversion, and soft tissue tension (Berry 2002, Mumme et al. 2004, Gutierrez et al. 2007). Modular cementless implant systems with a distal diaphyseal press-fit concept provide greater variability in difficult anatomical situations than non-modular revision stems (Berry 2002). The modular-designed components offer the opportunity to customize the prosthesis intraoperatively to the individual anatomical situation, allowing nearly physiological joint reconstruction (Gravius et al. 2011).Based on published studies, the modular cementless MRP-TITAN revision stem with its distal diaphyseal fixation concept has well-proven short-term effectiveness in femoral revision, especially for large femoral defects (types IIC and III, as described by Paprosky et al. (1990)). Previous studies have shown low mechanical failure rates of 2–5% after 4–5 years of follow-up (Wirtz et al. 2000, Mumme et al. 2004, 2007).Due to the relative lack of medium- to long-term results of femoral modular cementless revision surgery in the literature, we investigated the clinical and radiographic medium- to long-term outcome of femoral revision arthroplasty with the MRP-TITAN stem in a consecutive patient series.     

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).     

Similar TKA designs with differences in clinical outcome: a randomized, controlled trial of 77 knees with a mean follow-up of 6 years

Background and purpose

To try to improve the outcome of our TKAs, we started to use the CKS prosthesis. However, in a retrospective analysis this design tended to give worse results. We therefore conducted a randomized, controlled trial comparing this CKS prosthesis and our standard PFC prosthesis. Because many randomized studies between different TKA concepts generally fail to show superiority of a particular design, we hypothesized that these seemingly similar designs would not lead to any difference in clinical outcome.

Patients and methods

82 patients (90 knees) were randomly allocated to one or other prosthesis, and 39 CKS prostheses and 38 PFC prostheses could be followed for mean 5.6 years. No patients were lost to follow-up. At each follow-up, patients were evaluated clinically and radiographically, and the KSS, WOMAC, VAS patient satisfaction scores and VAS for pain were recorded.

Results

With total Knee Society score (KSS) as primary endpoint, there was a difference in favor of the PFC group at final follow-up (p = 0.04). Whereas there was one revision in the PFC group, there were 6 revisions in the CKS group (p = 0.1). The survival analysis with any reoperation as endpoint showed better survival in the PFC group (97% (95% CI: 92–100) for the PFC group vs. 79% (95% CI: 66–92) for the CKS group) (p = 0.02).

Interpretation

Our hypothesis that there would be no difference in clinical outcome was rejected in this study. The PFC system showed excellent results that were comparable to those in previous reports. The CKS design had differences that had considerable negative consequences clinically. The relatively poor results have discouraged us from using this design.Although current results of total knee arthroplasty (TKA) are relatively good, there is still room for improvement. There is constant research and development, with a view to obtaining longer survival rates (Rand et al. 2003, Julin et al. 2010), a better range of motion (high-flex TKA) (McCalden et al. 2009, Choi et al. 2010, Mehin et al. 2010), or a more anatomical reconstruction of the joint—such as posterior and anterior cruciate ligament retaining designs (Ries 2007, Pritchett 2011) and gender-specific TKA (Clarke and Hentz 2008, Kim et al. 2010).We started to use the CKS prosthesis (Stratec Medical, Oberdorf, Switzerland), based on previous research at our institution showing that the natural patella groove does not have an isolated lateral orientation (Barink et al. 2006). In contrast to our standard prosthesis (PFC; DePuy/Johnson and Johnson, Warsaw, IN) with a lateral orientation of the patellar groove, the trochlea of the CKS prosthesis is deeper and has a neutral direction. However, in a retrospective analysis, after 1 year the CKS prosthesis tended to have worse Knee Society scores (KSSs) (Brokelman et al. 2004). We decided to compare the outcome thoroughly and started a randomized, controlled trial between the CKS and the PFC prostheses.Many randomized studies of TKAs with different bearings (Harrington et al. 2009, Rahman et al. 2010), cruciate-retaining or -substituting devices (Kim et al. 2009), gender-specific designs (Kim et al. 2010), and high-flex designs (McCalden et al. 2009, Choi et al. 2010, Mehin et al. 2010) generally fail to show superiority of one of the devices over the other. We therefore hypothesized that the seemingly small differences in design between the CKS and PFC system would not lead to differences in clinical outcome in our study.     

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.     

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.     

Legg-Calvé-Perthes disease and the risk of injuries requiring hospitalization: A register study involving 2579 patients

Background and purpose

Previous studies have suggested that Legg-Calvé-Perthes disease (LCPD) is associated with repetitive trauma, coagulation problems and anatomical abnormalities of the blood supply to the femoral head. The hypothesis that repetitive trauma can affect the blood supply of the femoral head, leading to LCPD, is supported by an animal model. For evidence of an increased risk of repetitive trauma, we investigated whether patients with LCPD have a higher risk for severe injuries requiring hospitalization.

Patients and methods

We identified 2579 patients with LCPD in Sweden during the period 1964–2005. 13,748 individuals without LCPD were randomly selected from the Swedish general population, matched by year of birth, sex and region (control group). Cox proportional hazard regression estimated the risks.

Results

Compared to the control group, patients with LCPD had a modestly raised hazard ratio (HR) of 1.2 (95% CI 1.1–1.3) for injury requiring hospitalization. The risks were slightly higher for soft tissue injuries (HR = 1.3, 95% CI:1.1–1.4) than for fractures (HR = 1.1, 95% CI: 1.0–1.3) and more pronounced among females. Compared to the control group, the higher risk for injury only applied to the lower extremities (HR = 1.2, 95% CI: 1.0–1.4) in patients with LCPD.

Interpretation

Patients with LCPD are vulnerable to injuries which could be interpreted as a marker of hyperactive behavior. It could also implicate that anatomical changes in the bone formation or blood supply of the femoral head – increasing its sensibility for trauma – contribute to the etiology of LCPD.Legg-Calve-Perthes disease (LCPD) is an osteonecrosis of the femoral head epiphysis in children less than 15 years of age, with a peak age of diagnosis between 5 and 8 years of age. Boys are affected four times more often than girls. The disease is bilateral in 8–24% of patients (Guille et al. 1998).The etiology and pathophysiology of LCPD are still not completely understood. However, association between this disease and passive smoking, small stature, skeletal retardation, and low birth weight has been reported (Wynne-Davies and Gormley 1978, Hall et al. 1988, Rao et al. 1995, Eckerwall et al. 1996, Garcia Mata et al. 2000, Lappin et al. 2003). Disturbed circulation in the femoral head has been hypothesized, such as stasis in blood vessels because of increased intraarticular and intraosseous pressure or thromboembolic events as a result of coagulation abnormalities (Green and Griffin 1982, Liu and Ho 1991). It has also been suggested that anatomical changes in the blood supply with a reduced number or capacity of blood vessels may cause LCPD (Catterall 1971, Axer and Schiller 1972, de Camargo et al. 1984, Alpaslan et al. 2007). In earlier studies, repetitive trauma was suggested to affect the blood supply of the femoral head, leading to LCPD (Wynne-Davies and Gormley 1978, Douglas and Rang 1981). This phenomenon has been simulated and proven in an animal model in which mechanical stress was applied to the hip joints of ordinary growing Wistar Kyoto rats by forcing them to stand (Mihara and Hirano 1998, Suehiro et al. 2000, 2005). As children with hyperactive behavior are known to experience more injuries, (Uslu and Uslu 2008, Maxson et al. 2009, Merrill et al. 2009, Ertan et al. 2012) it has been suggested that hyperactivity disorders or attention deficit hyperactivity disorder (ADHD) might be more common among patients with LCPD (Loder et al. 1993).In this population-based cohort study using Swedish register data we investigated if patients with LCPD have higher risk of injury compared with the general population.