The effect of patella resurfacing in total knee arthroplasty on functional range of movement measured by flexible electrogoniometry

Different modalities of patellar management in primary total knee arthroplasty: a Bayesian network meta-analysis of randomized controlled trials

BACKGROUND

The primary management modalities for the patella in TKA include patellar resurfacing, patellar non-resurfacing, patellar resurfacing with denervation, and patellar non-resurfacing with denervation. Traditionally, meta-analyses have predominantly focused on examining comparisons between two management modalities. However, this study performed a network meta-analysis to compare all four patellar management interventions to identify the most optimal approach for patellar management in TKA.

METHODS

A computer-based search of PubMed, China National Knowledge Infrastructure (CNKI), The Cochrane Library, Web of science, Embase, and MEDLINE databases was performed to identify randomized controlled trials focusing on the four management interventions for the patella in TKA. Comparisons included two-by-two comparisons as well as those involving more than two concurrent comparisons. The search timeframe spanned from inception to June 30, 2023. Two independent authors extracted the data and evaluated the quality of the literature. The Cochrane Collaboration Risk of Bias (ROB) tool was used to evaluate the overall quality of the literature. Subsequently, a network meta-analysis was conducted using the "gemtc" package of the R-4.2.3 software. Outcome measures such as anterior knee pain (AKP), reoperation rate, and patient satisfaction rate were evaluated using odd ratio (OR) and 95% confidence intervals (CI). Additionally, the knee society score (KSS), function score (FS), and range of motion (ROM) were evaluated using mean differences (MD) with associated 95% CI. The different treatment measures were ranked using the surfaces under the cumulative ranking curves (SUCRA).

RESULTS

A total of 50 randomized controlled trials involving 9,283 patients were included in the analysis. The findings from this network meta-analysis revealed that patellar resurfacing exhibited significantly lower postoperative reoperation rate (OR 0.44, 95% CI 0.24-0.63) and AKP (OR 0.58, 95% CI 0.32-1) compared to non-resurfacing. Additionally, patellar resurfacing exhibited higher postoperative KSS clinical scores in comparison with non-resurfacing (MD: 1.13, 95% CI 0.18-2.11). However, for postoperative FS, ROM, and patient satisfaction, no significant differences were observed among the four management interventions.

CONCLUSION

Patellar resurfacing emerges as the optimal management modality in primary TKA. However, future studies should aim to reduce sources of heterogeneity and minimize the influence of confounding factors on outcomes.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023434418 identifier: CRD42023434418.

Spine patient care with wearable medical technology: state-of-the-art, opportunities, and challenges: a systematic review

BACKGROUND CONTEXT

Healthcare reforms that demand quantitative outcomes and technical innovations have emphasized the use of Disability and Functional Outcome Measurements (DFOMs) to spinal conditions and interventions. Virtual healthcare has become increasingly important following the COVID-19 pandemic and wearable medical devices have proven to be a useful adjunct. Thus, given the advancement of wearable technology, broad adoption of commercial devices (ie, smartwatches, phone applications, and wearable monitors) by the general public, and the growing demand from consumers to take control of their health, the medical industry is now primed to formally incorporate evidence-based wearable device-mediated telehealth into standards of care.

PURPOSE

To (1) identify all wearable devices in the peer-reviewed literature that were used to assess DFOMs in Spine, (2) analyze clinical studies implementing such devices in spine care, and (3) provide clinical commentary on how such devices might be integrated into standards of care.

STUDY DESIGN/SETTING

A systematic review.

METHODS

A comprehensive systematic review was conducted in adherence to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Guidelines (PRISMA) across the following databases: PubMed; MEDLINE; EMBASE (Elsevier); and Scopus. Articles related to wearables systems in spine healthcare were selected. Extracted data was collected as per a predetermined checklist including wearable device type, study design, and clinical indices studied.

RESULTS

Of the 2,646 publications that were initially screened, 55 were extensively analyzed and selected for retrieval. Ultimately 39 publications were identified as being suitable for inclusion based on the relevance of their content to the core objectives of this systematic review. The most relevant studies were included, with a focus on wearables technologies that can be used in patients' home environments.

CONCLUSIONS

Wearable technologies mentioned in this paper have the potential to revolutionize spine healthcare through their ability to collect data continuously and in any environment. In this paper, the vast majority of wearable spine devices rely exclusively on accelerometers. Thus, these metrics provide information about general health rather than specific impairments caused by spinal conditions. As wearable technology becomes more prevalent in orthopedics, healthcare costs may be reduced and patient outcomes will improve. A combination of DFOMs gathered using a wearable device in conjunction with patient-reported outcomes and radiographic measurements will provide a comprehensive evaluation of a spine patient's health and assist the physician with patient-specific treatment decision-making. Establishing these ubiquitous diagnostic capabilities will allow improvement in patient monitoring and help us learn about postoperative recovery and the impact of our interventions.

Outcomes and Survivorships of Total Knee Arthroplasty Comparing Resurfaced and Unresurfaced Patellae

BACKGROUND

The decision to resurface the patella in total knee arthroplasty (TKA) is controversial. While there is some consensus that leaving the patella unresurfaced increases risk of reoperation, there is conflicting evidence about patient reported outcomes or indications for resurfacing. This study sought to determine recent rates of patellar resurfacing, examine factors affecting rates of resurfacing, and analyze the associations between patellar resurfacing and both revision rates and patient-reported outcome measures (PROMs).

METHODS

The American Joint Replacement Registry was used to identify primary TKAs performed for osteoarthritis between 2012 and 2021. Cases were classified as resurfaced patella and unresurfaced patella (URP). Outcomes analyzed included trends in patellar resurfacing, factors influencing rate of resurfacing, revision rates, operative time, and 2 PROMs.

RESULTS

Rates of patellar resurfacing decreased and rates of URP increased significantly faster in ambulatory surgery centers and among high volume surgeons. Operative time was significantly lower in URP versus resurfaced patella (88.15 versus 89.90 minutes). The URP were significantly more likely to require revision surgery (odds ratio = 1.206 (1.078, 1.35), P = .0011). There was no significant difference in the likelihood of achieving the minimal clinically important difference in PROMs between resurfaced and nonresurfaced TKAs at 1 year (odds ratio = 1.060 (0.710, 1.581), P = .7755).

CONCLUSION

There was no difference in minimal clinically important difference between resurfaced and URPs and no clinically relevant difference in operative time. However, URPs were more likely to require revision surgery. Therefore, the decision not to resurface should be made carefully considering the known risk of revision and the uncertain benefit.

Patellar resurfacing versus retention in cruciate-retaining and posterior-stabilized total knee arthroplasty

Aims

This systematic review and meta-analysis aimed to compare the influence of patellar resurfacing following cruciate-retaining (CR) and posterior-stabilized (PS) total knee arthroplasty (TKA) on the incidence of anterior knee pain, knee-specific patient-reported outcome measures, complication rates, and reoperation rates.

Methods

A systematic review of MEDLINE, PubMed, and Google Scholar was performed to identify randomized controlled trials (RCTs) according to search criteria. Search terms used included: arthroplasty, replacement, knee (Mesh), TKA, prosthesis, patella, patellar resurfacing, and patellar retaining. RCTs that compared patellar resurfacing versus unresurfaced in primary TKA were included for further analysis. Studies were evaluated using the Scottish Intercollegiate Guidelines Network assessment tool for quality and minimization of bias. Data were synthesized and meta-analysis performed.

Results

There were 4,135 TKAs (2,068 resurfaced and 2,027 unresurfaced) identified in 35 separate cohorts from 33 peer-reviewed studies. Anterior knee pain rates were significantly higher in unresurfaced knees overall (odds ratio (OR) 1.84; 95% confidence interval (CI) 1.20 to 2.83; p = 0.006) but more specifically associated with CR implants (OR 1.95; 95% CI 1.0 to 3.52; p = 0.030). There was a significantly better Knee Society function score (mean difference (MD) -1.98; 95% CI -1.1 to -2.84; p < 0.001) and Oxford Knee Score (MD -2.24; 95% CI -0.07 to -4.41; p = 0.040) for PS implants when patellar resurfacing was performed, but these differences did not exceed the minimal clinically important difference for these scores. There were no significant differences in complication rates or infection rates according to implant design. There was an overall significantly higher reoperation rate for unresurfaced TKA (OR 1.46 (95% CI 1.04 to 2.06); p = 0.030) but there was no difference between PS or CR TKA.

Conclusion

Patellar resurfacing, when performed with CR implants, resulted in lower rates of anterior knee pain and, when used with a PS implant, yielded better knee-specific functional outcomes. Patellar resurfacing was associated with a lower risk of reoperation overall, but implant type did not influence this.

Patellar resurfacing was not associated with a clinically significant advantage when a modern patellar friendly total knee arthroplasty is employed: A systematic review and meta-analysis

BACKGROUND

Modern total knee arthroplasty (TKA) femoral components are designed to provide a more optimal articular surface for the patella whether or not it has been resurfaced. Previous systematic reviews comparing outcomes of patellar resurfacing and no resurfacing combine both historic and modern designs.

AIMS

The aim of this study was to investigate the effect of patellar resurfacing in modern "patellar friendly" implants on (1) incidence of anterior knee pain, (2) patient reported outcomes (3) complication rates, and (4) reoperation rates compared with unresurfaced patellae in primary TKA.

METHODS

MEDline, PubMed and google scholar studies were evaluated using SIGN assessment tool and data analysis was conducted using Review Manager 5.2 on only randomised controlled trials. The search terms were: arthroplasty, replacement, knee (Mesh), TKA, prosthesis, patella, patellar resurfacing, patellar retaining.

RESULTS

Thirty-two randomised controlled studies were identified that reported the type of TKA implant used: 11 used modern "patellar friendly" implants; and 21 older "patellar non-friendly" implants. Among "patellar friendly" TKAs there were no significant differences in anterior knee pain rates between resurfaced and unresurfaced groups. Patellar resurfacing with "patellar friendly" implants had significantly higher clinical (mean difference (MD) -0.77, p = 0.007) and functional (MD -1.87, p < 0.0001) knee society scores (KSS) than unresurfaced counterparts but these did not exceed the minimal clinically important difference (MCID). Resurfacing with "patellar friendly" implants was not associated with a significant (p = 0.59) difference in the Oxford knee score (OKS), in contrast when a "patellar non-friendly" implant was used there was a significant difference (MD 3.3, p = 0.005) in favour of resurfacing. There was an increased risk of reoperation for unresurfaced TKAs with "non-patellar friendly" implants (Odds ratio (OR) 1.68, 95% CI 1.03-2.74, p = 0.04), but not for unresurfaced patellae with "patellar friendly" implants (OR 1.17, CI 0.59-2.30).

CONCLUSIONS

Patellar resurfacing in combination with a modern patellar friendly implant was not associated with a lower rate of anterior knee pain, complications, or reoperations compared to not resurfacing, nor did it give a clinically significant improvement in knee specific function. In contrast patellar resurfacing in combination with a "non-friendly" TKA implant was associated with a significantly better OKS and lower reoperation rate. Implant design should be acknowledged when patellar resurfacing is being considered.

Patellar Resurfacing in Primary Total Knee Arthroplasty: A Meta-analysis and Trial Sequential Analysis of 50 Randomized Controlled Trials

OBJECTIVE

During total knee arthroplasty, femur and tibia parts are regularly replaced, while resurfacing the patellar or not is an ongoing discussion. To compare revision rate, anterior knee pain rate, patient-reported outcome measures, complication, radiographic, and clinical outcomes after patellar resurfacing versus non-resurfacing in total knee arthroplasty.

METHODS

PubMed, Medline, EMBASE, CENTRAL, and CINAHL databases were searched on 25 April 2021 to enroll randomized controlled trials that compared patellar resurfacing versus non-resurfacing. We used the grading of recommendations assessment, development and evaluation (GRADE) framework to assess the certainty of evidence. Our primary outcome was revision rate and secondary outcomes was anterior knee pain rate. Outcomes were pooled using the random-effect model and presented as risk ratio (RR), or mean difference (MD), with 95% confidence interval (CI).

RESULTS

Fifty studies (5586 knees) were included. Significant reductions in patellar revision rate (RR 0.41, 95% CI [0.19, 0.88]; P = 0.02; I²  = 24.20%) and non-patellar revision rate (RR 0.64, 95% CI [0.55, 0.75]; P < 0.001; I²  = 0%) were seen after patellar resurfacing. Patellar resurfacing significantly reduced the anterior knee pain rate than nonresurfacing (RR 0.72, 95% CI [0.57, 0.91]; P = 0.006; I²  = 69.5%). Significant differences in patient-reported outcome measures were found. However, these differences were inconsistent and lacked clinical importance. Patellar resurfacing resulted in a significant lower rate of patellar clunk (RR 0.58, 95% CI [0.38, 0.88]; P = 0.01; I²  = 0%), a higher patellar score (MD 1.24, 95% CI [0.67, 0.81]; P < 0.001; I²  = 73.8%), but prolonged surgical time (MD 8.59, 95% CI [5.27, 11.91]; P < 0.001; I²  = 88.8%).

CONCLUSIONS

The clear relationship is that patellar resurfacing reduces revisions, anterior knee pain, and patellar clunk. It will be interesting to compare the initial cost with the revision cost when required and cost-utility analysis with long-term results in future studies.

Comparison of wearable sensor to traditional methods in functional outcome measures: A systematic review

Traditional methods of collecting functional outcome measures are widely used for lower extremity arthroplasty outcome assessment. Wearable sensors are emerging as viable tools for functional outcome measures in monitoring of postarthroplasty recovery. The objective of this review was to compare the efficacy of wearable sensors with traditional methods for monitoring postarthroplasty functional recovery. Articles were searched for inclusion in this review that used both traditional and wearable sensor functional outcome measures to assess lower extremity function before and after lower extremity arthroplasty. Two independent screeners reviewed all articles, and resolved differences through consensus and consultation with the senior author. Studies that met inclusion criteria were evaluated for methodologic quality using performed risk of bias assessments. Results from several traditional and wearable sensor functional outcome measures from baseline through follow-up were normalized across studies. Fourteen articles met the inclusion criteria. Six studies used statistical methods to directly compare functional outcome measures and eight studies used qualitative description of comparisons. This review found evidence that wearable sensors detected nuanced functional outcome information on the specific biomechanics and timing of recovery, which were unaccounted for using traditional methods. Wearable sensors have shown promising utility in providing additional recovery information from lower extremity arthroplasty compared with traditional functional outcome measures, but future research is needed to assess the clinical significance of this additional information. Wearable sensor technology is an emerging clinical tool providing advanced and determinative data with the potential for advancing the assessment of lower extremity arthroplasty outcomes.

Influences of treadmill speed and incline angle on the kinematics of the normal, osteoarthritic and prosthetic human knee

The objective of this paper is to measure and to study the influence of the treadmill speed and incline angle on the kinematics of flexion-extension angles of the human knee joints during 23 tests of walking overground and on plane and inclined treadmill performed by a sample of 14 healthy subjects and during of seven tests performed by a sample of five patients suffering of knee osteoarthritis (KOA), before and three months after the total knee replacement (TKR) surgery. The medium cycles computed and plotted for all experimental tests performed by the healthy subjects' sample and for the osteoarthritic (OA) patients' sample before and after TKR surgery are compared and conclusions are formulated.

Patellar resurfacing has minimal impact on in vitro tibiofemoral kinematics during deep knee flexion in total knee arthroplasty

BACKGROUND

While patellar resurfacing can affect patellofemoral kinematics, the effect on tibiofemoral kinematics is unknown. We hypothesized that patellar resurfacing would affect tibiofemoral kinematics during deep knee flexion due to biomechanical alteration of the extensor mechanism.

METHODS

We performed cruciate-retaining TKA in fresh-frozen human cadaveric knees (N = 5) and recorded fluoroscopic kinematics during deep knee flexion before and after the patellar resurfacing. To simulate deep knee flexion, cadaver knees were tested on a dynamic, quadriceps-driven, closed-kinetic chain simulator based on the Oxford knee rig design under loads equivalent to stair climbing. To measure knee kinematics, a 2-dimensional to 3-dimensional fluoroscopic registration technique was used. Component rotation, varus-valgus angle, and anteroposterior translation of medial and lateral contact points of the femoral component relative to the tibial component were calculated over the range of flexion.

RESULTS

There were no significant differences in femoral component external rotation (before patellar resurfacing: 6.6 ± 2.3°, after patellar resurfacing: 7.2 ± 1.8°, p = 0.36), and less than 1° difference in femorotibial varus-valgus angle between patellar resurfacing and non-resurfacing (p = 0.01). For both conditions, the medial and lateral femorotibial contact points moved posteriorly from 0° to 30° of flexion, but not beyond 30° of flexion. At 10° of flexion, after patellar resurfacing, the medial contact point was more anteriorly located than before patellar resurfacing.

CONCLUSION

Despite the potential for alteration of the knee extensor biomechanics, patellar resurfacing had minimal effect on tibiofemoral kinematics. Patellar resurfacing, if performed adequately, is unlikely to affect postoperative knee function.

Patellar resurfacing versus nonresurfacing in total knee arthroplasty: an updated meta-analysis of randomized controlled trials

BACKGROUND

Whether resurface the patella or not in total knee arthroplasty (TKA) was controversial. In 2013, we conducted a meta-analysis of randomized controlled trials (RTCs). After that, plenty of studies have been carried out, but there still existed a great deal of controversy. In order to update our previous study, we conducted this update meta-analysis to evaluate the efficacy of patellar resurfacing in TKA.

METHODS

Databases were searched for RCTs comparing the outcomes of patellar resurfacing and nonresurfacing in TKA. Outcomes of knee relevant indicators were analysed. To see the short- and long-term effects, we calculated the data in total and divided the patients who were followed up for ≤ 3 years and ≥ 5 years into two subgroups as well.

RESULTS

Thirty-two trials assessing 6887 knees were eligible. There was a significant difference in terms of reoperation (in total and ≥ 5 years), Knee Society Score (KSS), function score (in total and ≥ 5 years) and noise. While no significant difference was found in the following items: reoperation (≤ 3 years), anterior knee pain (AKP), function score (≤ 3 years), range of motion (ROM), Oxford score, the Knee Injury and Osteoarthritis Outcome Score (KOOS), visual analogue score (VAS), Feller score, patellar tilt and the patients' satisfaction.

CONCLUSIONS

We found that patellar resurfacing could reduce the occurrence of reoperation and noise after surgery, as well as increase the KSS and function score, while it might not influence the outcomes such as AKP, ROM, Oxford score, KOOS, VAS, Feller score, patellar tilt and the patients' satisfaction. The results are different from our previous finding in the meta-analysis. In conclusion, we prefer patellar resurfacing in TKA.

Role of positioning of femoral component in the anterior-posterior direction on postoperative anterior pain in TKA

INTRODUCTION AND PURPOSE

The patellofemoral joint has proved to be the most problematic element of modern TKA for postoperative anterior knee pain; the positioning of the femoral component constitutes a critical phase in this issue. The objective of our study was to evaluate the possible role of either anterior positioning or posterior positioning of the femoral shield compared to the reference plane represented by the anterior cortex, on the anterior knee pain after knee arthroplasty.

METHODS

Forty-eight patients treated with TKA were followed up approximately 12 months. None of them have been submitted to any patellar treatment. We observed the position of femoral shield with respect to the anterior cortical line of femur dividing patients into three groups: patients with significant notching, patients with no notching (shield corresponding to anterior cortical line) and patients with anterior positioning of shield. We evaluated clinical and functional outcomes with KSS, anterior knee pain with Kujala's score and adverse events such as periprosthetic fractures.

RESULTS

We found a better clinical and functional result for patients with femoral shield positioned in line with anterior cortical cortex with respect to both TKAs with femoral notching and to protruding anterior femoral components; there were no main differences in anterior postoperative score by Kujala's system. We observed a periprosthetic fracture in a patient with an important femoral notching.

CONCLUSIONS

We cannot consider our study as an objective conclusion to the argument. We need more RCTs in order to study the proper influence of either notching or protrusion of femoral shield component onto anterior postoperative pain. Anyway positioning of femoral shield in anterior-posterior direction could be an interesting new critical object of study about anterior knee pain after TKA.

Better outcomes with patellar resurfacing during primary total knee arthroplasty: a meta-analysis study

BACKGROUND

Total knee arthroplasty (TKA) is a feasible and cost-effective procedure. However, resurfacing of the patella sparks a heated debate. Anterior knee pain after TKA was supposed to be correlated to the patellofemoral joint, and the resurface of the patella was believed to be effective to avoid this complication.

AIM

A meta-analysis was performed to update current evidence concerning the outcomes of patellar resurfacing versus retaining for total knee arthroplasty. The first outcomes of interest were to compare the rate of anterior knee pain and revision surgeries.

MATERIAL AND METHODS

This study was conducted according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA). A comprehensive review of the literature was conducted accessing the main databases: Embase, Google Scholar, PubMed, Scopus. All the prospective clinical trials comparing the outcomes between patellar resurfacing versus retaining were included in this study. Only articles classified as level of evidence I to II were considered for inclusion. Only studies reporting a minimum 24 months follow-up were included. The following data were extracted: demographic baseline, anterior knee pain, reoperations, clinical scores (HSS, KSS and related subscales) and range of motion (ROM). Studies solely reporting quantitative data under the outcomes of interest were included.

RESULTS

In favor of the resurfacing group, we observed a statistically significant reduced rate of anterior knee pain (odd ratio 1.73) and reoperation (odd ratio 3.24). In the resurfacing group, a prevalence of anterior knee pain of 11.15% was detected, whereas in the retaining group it amounted to 17.39%. Furthermore, a greater KSS pain (+ 0.97%), KSS clinical (+ 0.23%), KSS functional (+ 2.44%), KSS overall (+ 2.47%) and HSS (+ 5.64%) were reported. In the retaining group, we found a better range of motion (+ 3.09°).

CONCLUSION

Based on the main findings of this meta-analysis, patellar resurfaced TKA was demonstrated to have performed superior overall. Patellar resurfacing detected a lower rate of postoperative anterior knee pain and reoperation. Moreover, the resurfacing group showed greater value of the HSS, KSS and related subscales. In favor of the retaining group, a slightly better ROM was evidenced.

LEVEL OF EVIDENCE

Level II, meta-analysis of prospective clinical trials.

The Challenge of Managing the "Third-Space" in Total Knee Arthroplasty: Review of Current Concepts

Total knee arthroplasty (TKA) is the best treatment for advanced knee osteoarthritis and it has proven to be durable and effective. Anterior knee pain (AKP) is still one of the most frequent complications after TKA, but sometimes no recognized macroscopic causes can be found. The correct treatment of patella is considered the key for a proper management of AKP. The inclusion of patellar resurfacing during TKA has been described as a potential method for the reduction of AKP. After surgeons started to resurface the patella, new complications emerged, such as component failure, instability, fracture, tendon rupture, and soft tissue impingement. Patelloplasty has been proposed as a good alternative to resurfacing but whether or not to resurface the patella is still a controversial topic in the literature. Therefore, patellofemoral joint is a complex critical aspect in TKA and choosing between the several options of treatment of patella could not be sufficient. In this review, evidence-based studies do not succeed in resolving this difficult argument. The accurate management of the so-called “third space” should include an accurate assessment of cartilage layers, balance of soft tissue, preoperative anterior tracking, and positioning of the femoral and tibial components. In fact, the selection of suitable implants and adherence to proper surgical technique are the fundamental principles for the success of TKA.

Patellar resurfacing versus patellar retention in primary total knee arthroplasty: a systematic review of overlapping meta-analyses

PURPOSE

The need of patellar resurfacing in total knee arthroplasty (TKA) is a subject of debate. This systematic review of overlapping meta-analyses aimed to assess and analyze current evidence regarding patellar resurfacing and non-resurfacing in TKA.

METHODS

A systematic literature search was performed in March 2017 in PubMed, CINAHL and Cochrane Library. Inclusion criteria were meta-analysis of randomized controlled trials that compared TKA with and without patellar resurfacing considering as outcomes re-operations rate, complications, anterior knee pain, functional scores. The quality of meta-analyses was evaluated with AMSTAR score and the most relevant meta-analysis was determined by applying the Jadad algorithm.

RESULTS

Ten meta-analyses, published between 2005 and 2015, were included in the systematic review. Two studies found a significantly increased Knee Society Score in the resurfacing group. According to four meta-analyses, anterior knee pain incidence was lower in resurfacing group. Six of the included studies described a greater risk of re-intervention in the non-resurfacing groups. The overall quality of included studies was moderate. The most relevant meta-analysis reported no differences in functional scores and incidence of anterior knee pain between the groups.

CONCLUSIONS

Comparable outcomes were found when comparing patellar resurfacing and non-resurfacing in TKA. The higher risk of re-operations after non-resurfacing should be interpreted with caution due to the methodological limitations of the meta-analyses regarding search criteria, heterogeneity and the inherent bias of easier indication to reoperation when the patella is not resurfaced. There is no clear superiority of patellar resurfacing compared to patellar retention.

LEVEL OF EVIDENCE

Level II, systematic review of meta-analyses.

A Meta-Analysis of Patellar Replacement in Total Knee Arthroplasty for Patients With Knee Osteoarthritis

BACKGROUND

This meta-analysis (MA) aims at comparing the clinical outcomes of resurfacing and nonresurfacing the patella in patients undergoing total knee arthroplasty in the treatment of knee osteoarthritis.

METHODS

Randomized controlled trials were included by retrieving data from electronic English databases. Both fixed and random-effects models were employed, and standardized mean difference and 95% confidence intervals were calculated. Stata13.1 software was used for statistical analysis for all the studies included to compare the differences in improving Knee Society Clinical Score and Knee Society Function Score as well as the reduction in rates of infection, reoperation, and anterior knee pain.

RESULTS

A total of 394 studies were initially included in this MA. About 20 randomized controlled trials which met the inclusion criteria were finally enrolled in this MA. The results of our MA showed that the reoperation rate of the patellar resurfacing group was lower than that of the nonresurfacing group. The subgroup analysis was performed according to the follow-up time and revealed that the increase in the Knee Society Clinical Score was higher in the patellar resurfacing group than that in the nonresurfacing group in the follow-up period of 1 to 2 years. The risk of reoperation rate was lower in the patellar resurfacing group than that in the nonresurfacing group, while there were no statistical differences in the follow-up time over 2 years.

CONCLUSION

Our study suggests that during the follow-up of 1 to 2 years, patellar resurfacing can significantly increase the Knee Society Clinical Score and reduce the reoperative rates in patients with knee osteoarthritis.

Patellar Resurfacing in Total Knee Arthroplasty: Systematic Review and Meta-Analysis

BACKGROUND

Patellar resurfacing in total knee arthroplasty remains controversial. The aim of this study is to evaluate this technique through an analysis of comparative studies in the current literature.

METHODS

We performed a comprehensive search of PubMed, MEDLINE, Cochrane, CINAHL, and EMBASE databases using various combinations of the keywords "Knee," "Replacement," "Prosthesis," "Patella," "Resurfacing," and "Arthroplasty." All articles relevant to the subject were retrieved, and their bibliographies were hand searched for further references relevant to primary patellar resurfacing in total knee arthroplasty. Only articles published in peer-reviewed journals were included in this systematic review.

RESULTS

The percentage for a reoperation was 1% for the patellar resurfacing group (17/1636) and 6.9% for the non-resurfacing group (118/1699) (odds ratio [OR] 0.18, 95% confidence interval [CI] 0.11-0.29, P < .00001). The patellar resurfacing group showed a significantly higher postop Knee Society Score (KSS) pain (OR 1.52, 95% CI 0.68-2.35, P = .004) and postop Hospital for Special Surgery score (OR 4.35, 95% CI 3.21-5.49, P < .00001), over the non-resurfacing group.

CONCLUSION

Based on the outcome scores of KSS (pain), KSS (function), and Hospital for Special Surgery postop, patellar resurfacing TKAs have performed better than non-resurfaced TKAs. The lower secondary operation and revision rates for patellar resurfaced TKAs also demonstrate that this technique is the more effective option. However, the full impact of patellar resurfacing still needs to be critically evaluated by larger randomized controlled trials with long-term follow-up.

Patellar Resurfacing Versus Circumferential Denervation of the Patella in Total Knee Arthroplasty

This study compared the rates of anterior knee pain and functional outcomes between resurfaced patellas and non-resurfaced patellas with a circumpatellar denervation. One hundred ten patients who underwent patellar resurfacing or a circumpatellar denervation were evaluated for knee pain and functional outcomes at a minimum of 2 years after total knee arthroplasty. There were no significant differences between the 2 groups regarding Knee Society Scores, anterior knee pain scores, or visual analog scale scores. The groups had similar incidences of anterior knee pain. Most patients reported no to mild effect of anterior knee pain on daily living. Patients in each group reported increased pain with kneeling, squatting, and departing an automobile. Similar proportions of patients were disappointed with their overall outcomes in each group. Circumpatellar denervation and patellar resurfacing during total knee arthroplasty lead to similar incidences of anterior knee pain. [Orthopedics. 2016; 39(5):e1019-e1023.].

Predictors of flexion using the rotating concave-convex total knee arthroplasty: preoperative range of motion is not the only determinant

PURPOSE

The range of motion achieved after a total knee arthroplasty (TKA) affects many daily activities and overall patients' satisfaction. This study aims to define the determinants affecting post-operative midterm active flexion according to a specific cruciate-sacrificing prosthesis, the rotating concave-convex (ROCC(®)) TKA.

METHOD

Four hundred and eighty-four consecutive patients (584 TKAs) were prospectively followed. After baseline patient demographics and anatomical characteristics, clinical and radiological post-operative assessments were periodically recorded. The rotational alignment of the femoral component was additionally reported for 120 patients. Eligibility for final inclusion was a minimum of 5-year follow-up. Univariate analyses followed by a multivariate model were fitted to determine the independent predictors of midterm active knee flexion.

RESULTS

Thirty-four TKA (5.8%) were excluded for a secondary surgery before their 50 years, 69 patients died (11.8%), and 21 (3.6%) were lost to follow-up. Overall, 460 TKAs were included. The post-operative mean knee flexion angle was measured at 127.7° ± 9.3°. Significant factors affecting final flexion under univariate analyses were the patient height and body mass index, the absence of previous surgery, a depressive state, the preoperative flexion angle, a preoperative flexion contracture, a patellar residual subluxation, the reconstructed patellar height, and the rotation of the femoral component. The multivariate model confirmed the patient's height, a depression, the preoperative flexion angle, a patellar residual subluxation, and the patellar height as statistically significant determinants.

CONCLUSION

Aside from the preoperative flexion angle, numerous predictors of flexion, both patient- and procedure-related were identified. Surgeons should take these into account both when adequately informing their patient before surgery and when performing the arthroplasty itself.

LEVEL OF EVIDENCE

Prognostic, Level II.

Patellofemoral resurfacing and patellar denervation in primary total knee arthroplasty

PURPOSE

To conduct a systematic review and network meta-analysis of randomized controlled trials (RCTs) with the aim of comparing relevant clinical outcomes between patellar denervation, resurfacing and non-resurfacing.

METHODS

A database search was performed using PubMed and Scopus search engines. RCTs or quasi-experimental designs comparing clinical outcomes between treatments by a search of articles dated from inception to October 23, 2012. Unstandardized mean difference (UMD) and random effects methods were applied for pooling continuous and dichotomous outcomes, respectively. A longitudinal mixed regression model was used for network meta-analysis to indirectly compare treatment effects.

RESULTS

Eighteen of 315 studies identified were eligible. Compared with patellar non-resurfacing, patellar denervation had a UMD that displayed a significant improvement in symptoms with values in pain visual analog score (VAS) and Knee Society Score (KSS) of -0.6 [95% confidence interval (CI) -1.13, -0.25] and 2.55 (95% CI 0.43, 4.68), respectively. The UMD in VAS, KSS, and Knee Function Score (KFS) in patellar resurfacing showed no significant improvement in symptoms when compared to non-resurfacing. Patients who underwent surgery with patellar resurfacing had a lower reoperation rates with pooled relative risks (RRs) of 0.69 (95% CI 0.50, 0.94) when compared to non-resurfacing. The network meta-analysis suggested a benefit of borderline significance for patellar denervation with a pooled RR of 0.63 (95% CI 0.38, 1.03), showing that there is a lower chance of anterior knee pain when compared to non-resurfacing. Patellar resurfacing also displays a significantly lower chance of reoperation with a pooled RR of 0.68 (95% CI 0.50, 0.92) when compared to non-resurfacing. Multiple active treatment comparisons indicated that patellar denervation resulted in greater improvement in KFS than patellar resurfacing.

CONCLUSION

This review suggests that either patellar denervation or patellar resurfacing may be selected for the management of the patellofemoral component in total knee replacement. Patellar denervation may help improve postoperative knee function, but does not improve pain when compared to patellar resurfacing.

Effect of patellar thickness on early results of total knee replacement with patellar resurfacing

PURPOSE

Patellar thickness is a concern in total knee replacement with patellar resurfacing because of the risk of patellar fracture or implant loosening. The aim of this study was to evaluate if patellar thickness is related to clinical outcome in the absence of patellar fracture or implant loosening.

METHODS

Early results of 169 patients who underwent total knee replacement with patellar resurfacing were reviewed to assess the effect of patellar thickness on clinical outcome. The mean follow-up was 13 months. The range of motion, Knee Society Score, Function Score and WOMAC Score were assessed preoperatively, at day 0, 6 months and 1 year. Radiographs were assessed for patellar fracture or implant loosening.

RESULTS

Thirty-one percent of all patients had preoperative thickness <21 mm. Seven percent had <12 mm residual thickness after patellar cut, all were female. Twenty-three percent had ≥1 mm increase of thickness after surgery. Radiographs did not show any patellar fracture or implant loosening. However, preoperative patellar thickness <21 mm had poorer gain in range of motion at 1 year. Preoperative range of motion had greater influence on postoperative range of motion than preoperative patellar thickness. Residual thickness <12 mm had lower gain in WOMAC score at 1 year and an increase in thickness ≥1 mm postoperatively was associated with lower gain in WOMAC score at 6 months.

CONCLUSIONS

Early results of patellar resurfacing with preoperative thickness <21 mm or residual thickness <12 mm were found to be inferior even in the absence of patellar fracture or implant loosening. Conservative cutting resulting in 1 mm increase in thickness was also found to have inferior clinical results.

LEVEL OF EVIDENCE

II.

Quantified self and human movement: a review on the clinical impact of wearable sensing and feedback for gait analysis and intervention

The proliferation of miniaturized electronics has fueled a shift toward wearable sensors and feedback devices for the mass population. Quantified self and other similar movements involving wearable systems have gained recent interest. However, it is unclear what the clinical impact of these enabling technologies is on human gait. The purpose of this review is to assess clinical applications of wearable sensing and feedback for human gait and to identify areas of future research. Four electronic databases were searched to find articles employing wearable sensing or feedback for movements of the foot, ankle, shank, thigh, hip, pelvis, and trunk during gait. We retrieved 76 articles that met the inclusion criteria and identified four common clinical applications: (1) identifying movement disorders, (2) assessing surgical outcomes, (3) improving walking stability, and (4) reducing joint loading. Characteristics of knee and trunk motion were the most frequent gait parameters for both wearable sensing and wearable feedback. Most articles performed testing on healthy subjects, and the most prevalent patient populations were osteoarthritis, vestibular loss, Parkinson's disease, and post-stroke hemiplegia. The most widely used wearable sensors were inertial measurement units (accelerometer and gyroscope packaged together) and goniometers. Haptic (touch) and auditory were the most common feedback sensations. This review highlights the current state of the literature and demonstrates substantial potential clinical benefits of wearable sensing and feedback. Future research should focus on wearable sensing and feedback in patient populations, in natural human environments outside the laboratory such as at home or work, and on continuous, long-term monitoring and intervention.

Early PROMs following total knee arthroplasty--functional outcome dependent on patella resurfacing

Patella resurfacing during primary total knee arthroplasty (TKA) remains controversial. Variation in published results for patella resurfacing may potentially be explained by differences in design between TKA brands. We interrogated NJR-PROMs data to ascertain whether there is an early functional benefit to resurfacing the patella, both overall and for each of the five most popular primary knee designs through use of the Oxford Knee Score. A total of 8103 resurfaced TKAs and 15,290 nonresurfaced TKAs were studied. There was a large variation in the proportion of knees undergoing patella resurfacing by brand (Nexgen=16% versus Triathlon=52%). Patellar resurfacing did not significantly influence the magnitude of improvement in overall knee function or anterior knee-specific function irrespective of TKA brand or for cruciate retaining versus sacrificing designs.

The controversy of patellar resurfacing in total knee arthroplasty: Ibisne in medio tutissimus?

Early arthroplasty designs were associated with a high level of anterior knee pain as they failed to cater for the patello-femoral joint. Patellar resurfacing was heralded as the saviour safeguarding patient satisfaction and success but opinion on its necessity has since deeply divided the scientific community and has become synonymous to topics of religion or politics. Opponents of resurfacing contend that the native patella provides better patellar tracking, improved clinical function, and avoids implant-related complications, whilst proponents argue that patients have less pain, are overall more satisfied, and avert the need for secondary resurfacing. The question remains whether complications associated with patellar resurfacing including those arising from future component revision outweigh the somewhat increased incidence of anterior knee pain recorded in unresurfaced patients. The current scientific literature, which is often affected by methodological limitations and observer bias, remains confusing as it provides evidence in support of both sides of the argument, whilst blinded satisfaction studies comparing resurfaced and non-resurfaced knees generally reveal equivalent results. Even national arthroplasty register data show wide variations in the proportion of patellar resurfacing between countries that cannot be explained by cultural differences alone. Advocates who always resurface or never resurface indiscriminately expose the patella to a random choice. Selective resurfacing offers a compromise by providing a decision algorithm based on a propensity for improved clinical success, whilst avoiding potential complications associated with unnecessary resurfacing. Evidence regarding the validity of selection criteria, however, is missing, and the decision when to resurface is often based on intuitive reasoning. Our lack of understanding why, irrespective of pre-operative symptoms and patellar resurfacing, some patients may suffer pain following TKA and others may not have so far stifled our efforts to make the strategy of selective resurfacing succeed. We should hence devote our efforts in defining predictive criteria and indicators that will enable us to reliably identify those individuals who might benefit from a resurfacing procedure. Level of evidence V.

Revision surgery for patellofemoral problems: should we always resurface?

BACKGROUND

Routine patellar resurfacing performed at the time of knee arthroplasty is controversial, with some evidence of utility in both TKA (tricompartmental) and bicompartmental knee arthroplasty. However, whether one approach results in better implant survival remains unclear.

QUESTIONS/PURPOSES

We asked whether (1) routine patellar resurfacing in TKAs resulted in lower cumulative revision rates compared to bicompartmental knee arthroplasties, (2) patella-friendly implants resulted in lower cumulative revision rates than earlier designs, and (3) bicompartmental knee arthroplasties revised to TKAs had higher cumulative revision rates than primary TKAs.

PATIENTS AND METHODS

From a community-based joint registry, we identified 8135 patients treated with 9530 cemented, all-polyethylene patella TKAs and 627 bicompartmental knee arthroplasties without patellar resurfacing. We compared age, gender, year of index procedure, diagnosis, cruciate status, revision, and revision reason.

RESULTS

TKAs had a lower cumulative revision rate for patella-only revision than bicompartmental knee arthroplasties (0.8% versus 4.8%). Adjusting for age, bicompartmental knee arthroplasties were 6.9 times more likely to undergo patellar revision than TKAs. There was no difference in the cumulative revision rate for patella-only revisions between patella-friendly and earlier designs. The cumulative revision rate for any second revision after a patella-only revision was 12.7% for bicompartmental knee arthroplasties while that for primary TKAs was 6.3%.

CONCLUSIONS

Bicompartmental knee arthroplasties had higher revision rates than TKAs. Femoral component design did not influence the cumulative revision rate. Secondary patella resurfacing in a bicompartmental knee arthroplasty carried an increased revision risk compared to resurfacing at the time of index TKA. To reduce the probability of reoperation for patellofemoral problems, our data suggest the patella should be resurfaced at the time of index surgery.

Is patellar resurfacing superior than nonresurfacing in total knee arthroplasty? A meta-analysis of randomized trials

Conflicting results from abundant studies have made it unclear whether the patella should be resurfaced during total knee replacement. A meta-analysis was undertaken to pool the results of randomized controlled studies (RCTs) and to compare the outcomes and postoperative complications after total knee arthroplasty with patellar resurfacing or nonresurfacing. Sixteen RCTs including 3034 knees between 1966 and December 2009 were analyzed. Reoperation for patellofemoral problems was significantly more likely in the nonresurfacing group (P = 0.03). There was no difference between the two groups in terms of anterior knee pain rate, knee pain score, knee society score and knee function score. The results indicate that patellar resurfacing would reduce the risk of reoperation after total knee replacement, but it seems that the benefits are limited on other aspects, and the analysis of high-quality studies shows no advantage of resurfacing over nonresurfacoing group, even in the aspect of reoperation risk. More carefully and scientifically designed RCTs are beneficial and necessary to further prove the results.

The need for patellar resurfacing in total knee arthroplasty: a literature review

The controversy over whether or not to routinely resurface the patella during a total knee arthroplasty has persisted despite three decades of successful joint replacement procedures. Advocates for routine patellar resurfacing admit the occasional need for secondary patellar resurfacing and declare increased incidence of anterior knee pain in patients with non-resurfaced patellae as a cause for worry. Surgeons that leave the patella unresurfaced cite avoidance of complications that include patellar fracture, avascular necrosis, patellar tendon injury and instability. This review discusses the available literature on patellar resurfacing through an evidence-based analysis of randomized and pseudo-randomized controlled trials and published meta-analyses to date. The published literature seems to favour resurfacing the patellar routinely. Selective patellar resurfacing would be the ideal solution if sound pre-operative criteria could be established. So far, a method for accurately predicting which patients can avoid patellar resurfacing has not been found. Future research looking at patellar resurfacing should concentrate on developing criteria for selecting those patients that would benefit from patellar resurfacing and those that would do as well without resurfacing, and thus, limiting potential surgical complications.

Range of motion and repeatability of knee kinematics for 11 clinically relevant motor tasks

Standard gait analysis reports knee joint rotations in the three anatomical planes without addressing their different levels of reliability. Most clinical studies also restrict analysis to knee flexion-extension, because knee abduction-adduction and axial rotation are small with respect to the corresponding amount of measurement artefact. This study analyses a set of 11 motor tasks, in order to identify those that are adequately repeatable and that can induce greater motion at the knee than walking. Ten volunteers (mean ± SD age: 29 ± 9 years) each underwent three motion analysis sessions on different days with a standard gait analysis system and protocol. In each session they performed normal walking, walking with sidestep and crossover turns, ascent onto and descent off a step, descent with sidestep and crossover turns, chair rise, mild and deep squats, and lunge. Range and repeatability of motions in the three anatomical planes were compared by ANOVA. The sidestep turns showed a range of axial rotation significantly larger than that in walking (about 8°), while maintaining similar levels of repeatability. Ascent, chair rise, squat, and lunge showed greater flexion ranges than walking; among these, ascent was the most repeatable. The results show that turning increases knee axial rotation in young subjects significantly. Further, squats and lunges, currently of large interest in orthopaedics and sports research, have smaller repeatability, likely accounted for to the smaller constraints than in the traditional motor tasks.

Dairy farm worker exposure to awkward knee posture during milking and feeding tasks

Musculoskeletal disorders are common among agricultural workers, particularly among dairy farm workers. Specifically, dairy farm workers have been identified as being at risk for knee osteoarthritis. Physical risk factors that may contribute to knee osteoarthritis include awkward postures of the knee, such as kneeling or squatting. The purpose of this study was to quantify exposure to awkward knee posture among dairy farm workers during milking and feeding tasks in two common types of milking facilities (stanchion and parlor). Twenty-three dairy farm workers performed milking and feeding tasks; 11 worked in a stanchion milking facility, and 12 worked in a parlor milking facility. An electrogoniometer was used to measure knee flexion during 30 min of the milking and feeding tasks. Milking in a stanchion facility results in a greater duration of exposure to awkward posture of the knee compared with milking in a parlor facility. Specifically, the percentage of time in >or=110 degrees knee flexion was significantly greater in the stanchion facility (X = 17.7; SE 4.2) than in the parlor facility (X = 0.05; SE 0.04; p <or= 0.05). Similar results were observed with other categories of awkward knee posture in both milking and feeding tasks. This study supports previous findings that working in stanchion milking facility results in greater exposure to awkward knee posture compared with working in a parlor milking facility.

Normal functional range of motion of the lumbar spine during 15 activities of daily living

STUDY DESIGN

Prospective clinical study.

OBJECTIVE

The purpose of this investigation was to quantify normal lumbar range of motion (ROM) and compare these results with those used to perform 15 simulated activities of daily living (ADLs) in asymptomatic subjects.

SUMMARY OF BACKGROUND DATA

Previous studies reporting the ROM of the lumbar spine during ADLs have been limited, only focusing on 4 ADLs. The purpose of this investigation was to quantify the extent of normal lumbar ROM and determine how much motion is necessary to perform 15 simulated ADLs.

METHODS

A noninvasive electrogoniometer and torsiometer were used to measure the ROM of the lumbar spine. The accuracy and reliability of the devices were confirmed by comparing the ROM values acquired from dynamic flexion/extension and lateral bending radiographs with those provided by the device that was activated while the radiographs were obtained. Intraobserver reliability was established by calculating the intraclass correlation coefficient for repeated measurements on the same subjects by 1 investigator on consecutive days. These tools were employed in a clinical laboratory setting to evaluate the full active ROM of the lumbar spines (ie, flexion/extension, lateral bending, and axial rotation) of 60 asymptomatic subjects (30 women and 30 men; age 20 to 75 y) and to assess the functional ROM required to complete 15 simulated ADLs.

RESULTS

When compared with radiographic measurements, the electrogoniometer was found to be accurate within 2.3+/-2.6 degrees (mean+/-SD). The intraobserver reliabilities for assessing full and functional ROM were both excellent (intraclass correlation coefficient of 0.96 and 0.88, respectively). The absolute ROM and percentage of full active lumbar spinal ROM used during the 15 ADLs was 3 to 49 degrees and 4% to 59% (median: 9 degrees/11%) for flexion/extension, 2 to 11 degrees and 6% to 31% (6 degrees/17%) for lateral bending, and 2 to 7 degrees and 6% to 20% (5 degrees/13%) for rotation. Picking up an object from the ground, either using a bending or squatting technique, required the most ROM of all the ADLs. Squatting required a significantly less amount of sagittal motion compared with bending at the waist (42 vs. 48 degrees, P=0.003). No difference was seen in both lateral and rotation motion between these 2 techniques (11 vs. 11 degrees and 6 vs. 6 degrees, respectively). Both ascending and descending stairs required equivalent amounts of total motion in all 3 motion planes. As a whole, personal hygiene ADLs (hand washing, washing hair, shaving, and make-up application) required a similar amount of motion compared with the 3 locomotive ADLs (walking, up and down stairs).

CONCLUSIONS

By quantifying the amounts of lumbar motion required to execute a series of simulated ADLs, this study indicates that most individuals use a relatively small percentage of their full active ROM when performing such activities. These findings provide baseline data that may allow clinicians to accurately assess preoperative impairment and postsurgical outcomes.

Early outcomes of patella resurfacing in total knee arthroplasty

BACKGROUND

Patella resurfacing in total knee arthroplasty is a contentious issue. The literature suggests that resurfacing of the patella is based on surgeon preference, and little is known about the role and timing of resurfacing and how this affects outcomes.

METHODS

We analyzed 134,799 total knee arthroplasties using data from the Australian Orthopaedic Association National Joint Replacement Registry. Hazards ratios (HRs) were used to compare rates of early revision between patella resurfacing at the primary procedure (the resurfacing group, R) and primary arthroplasty without resurfacing (no-resurfacing group, NR). We also analyzed the outcomes of NR that were revised for isolated patella addition.

RESULTS

At 5 years, the R group showed a lower revision rate than the NR group: cumulative per cent revision (CPR) 3.1% and 4.0%, respectively (HR = 0.75, p < 0.001). Revisions for patellofemoral pain were more common in the NR group (17%) than in the R group (1%), and "patella only" revisions were more common in the NR group (29%) than in the R group (6%). Non-resurfaced knees revised for isolated patella addition had a higher revision rate than patella resurfacing at the primary procedure, with a 4-year CPR of 15% and 2.8%, respectively (HR = 4.1, p < 0.001).

INTERPRETATION

Rates of early revision of primary total knees were higher when the patella was not resurfaced, and suggest that surgeons may be inclined to resurface later if there is patellofemoral pain. However, 15% of non-resurfaced knees revised for patella addition are re-revised by 4 years. Our results suggest an early beneficial outcome for patella resurfacing at primary arthroplasty based on revision rates up to 5 years.

Actual knee motion during continuous passive motion protocols is less than expected

Investigations of the usefulness of continuous passive motion (CPM) after TKA have yielded mixed results, with evidence suggesting its efficacy is contingent on the presence of larger motion arcs. Surprisingly, the range of motion (ROM) the knee actually experiences while in a CPM machine has not been elucidated. In this study, the ability of a CPM apparatus to bring about a desired knee ROM was assessed with an electrogoniometer. The knee experienced only 68% to 76% of the programmed CPM arc, with the higher percentages generated by elevating the head of the patient's bed. This disparity between true knee motion and CPM should be accounted for when designing CPM protocols for patients or investigations evaluating efficacy of CPM.

Resurfacing versus nonresurfacing the patella in total knee arthroplasty: a critical appraisal of the available evidence

A systematic literature search for evidences comparing treatment effect and harm of resurfacing versus nonresurfacing the patella in total knee arthroplasty was conducted and yielded five meta-analysis (MA), one systematic review (SR) and six randomized controlled trials not included in previous MAs/SR. The evidence suggests that patellar resurfacing would reduce the risk of anterior knee pain, as well as the risk of patella-related reoperation. Furthermore, patients not undergoing patella resurfacing would experience more knee pain during stair climbing and be less satisfied with surgery. No significant difference in range of motion can be expected with or without patellar resurfacing. Importantly, methodological limitations were observed in all retrieved studies and evidences about potential adverse events related to patellar resurfacing are presently undetermined.

Predicting range of movement after knee replacement: the importance of posterior condylar offset and tibial slope

We have attempted to quantify the influence of clinical, radiological and prosthetic design factors upon flexion following knee replacement. Our study examined the outcome following 101 knee replacements performed in two prospective randomized trials using similar cruciate retaining implants. Multivariate analyses, after adjusting for age, sex, diagnosis and the type of prosthesis revealed that the only significant correlates for range of movement at 12 months were the difference in posterior condylar offset ratio (p < 0.001), tibial slope (p < 0.001) and preoperative range of movement (p = 0.025). We found a moderate correlation between 12-month range of movement and posterior tibial slope (R = 0.58) and the difference of post femoral condylar offset (i.e, post-operative minus preoperative posterior condylar offset, R = 0.65). Posterior condylar offset had the greatest impact upon final range of movement highlighting this as an important consideration for the operating surgeon at pre-operative templating when choosing both the design and size of the femoral component.

Between-day repeatability of knee kinematics during functional tasks recorded using flexible electrogoniometry

The objective of this study was to assess the between-day repeatability of knee kinematics during activities of daily living recorded by electrogoniometry. One rater assessed the peak knee angles and knee excursion of 15 subjects during 13 activities twice with an average of 22 days (range 5-31) between the two assessments. The 15 subjects included four patients one year after total knee replacement (TKR) surgery, five patients before TKR surgery and six age-matched controls. Intra-class correlation coefficients and Bland and Altman coefficient of repeatability were derived to analyse the results. Only the most affected leg of the patients and the right leg of the controls were used for analysis. Different measures of repeatability showed different results. Intra-class correlation coefficients were higher than 0.75 for peak values of all functions except sitting down and rising from a standard chair. However, coefficients of repeatability ranged from 5.6 degrees for the loading response in level walking to 39.8 degrees for stepping out of a bath. Both of these values are higher than clinically significant changes seen after total knee surgery. It was concluded that for a single assessment on individual patients, the functional knee motion as performed in this study did not have sufficient repeatability. However, if the measurements are used to assess the average changes before and after surgery in a group of patients, the assessment of knee motion during activities such as level walking, and slope and stair ascending and descending were found to be sufficiently repeatable.

Knee kinematics in functional activities seven years after total knee arthroplasty

BACKGROUND

Detailed knowledge of knee kinematics during functional activities is lacking in current studies on the long-term outcome of total knee replacement surgery. The aim of this study was to assess functional knee kinematics using flexible electrogoniometry in patients seven years after unilateral primary total knee arthroplasty for osteoarthritis.

METHODS

The knee joint functional movement of a cohort of patients (n=19) with knee osteoarthritis was assessed using electrogoniometry before surgery and 18-24 months and seven years after total knee surgery. The mean age of the patients (11 women and 8 men) at the time of the pre-surgery assessment was 67 years old (SD 8.0). Patient function was also assessed using the Knee Society Score and WOMAC osteoarthritis Index.

FINDINGS

The function components of the Knee Society and WOMAC scores were significantly decreased at seven years compared to 18-24 months after surgery (both P<0.05). However, the majority of the functional knee flexion values derived from electrogoniometry did not decrease. Seven years after surgery, knee excursion during ascending and descending stairs was significantly improved compared to 18-24 months after surgery (both P<0.01).

INTERPRETATION

The finding that functional knee motion continues to improve between 18-24 months and seven years post-surgery is of interest to both patients and those responsible for their treatment planning. Further, it was shown that the WOMAC and Knee Society Scores do not follow the same trends as the patients' functional knee kinematics seven years after total knee replacement surgery.