Resurfacing versus not resurfacing the patella in total knee arthroplasty: 8- to 10-year results

The influence of implant factors on patient outcomes in primary total knee arthroplasty

Background

The influence of implant factors on patient-reported outcome measures (PROMS) after total knee arthroplasty (TKA) has previously been studied but findings are often inconsistent, restricted in scope and biased by confounding factors. This study aims to determine the association between implant-related factors and early post-operative PROMs after TKA.

Methods

Using data from the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) PROMs program, the study included 9487 primary TKA procedures performed in 43 hospitals from July 31, 2018 to December 31, 2020. Data included baseline demographic data, surgical details and PROMs collected pre- and 6 months post-operatively. Seven prosthesis characteristics were incorporated in the multivariable model, with proportional odds ordinal regression analysis used to assess their effects on post-operative Oxford knee score (OKS) and joint pain. Adjustments were made for pre-operative OKS and joint pain, as well as potential patient confounders.

Results

At six months, fixed bearing implants showed higher odds of better OKS compared to mobile bearing implants (odds ratio [OR] = 1.20, 95 % confidence interval [CI] 1.06-1.37. p < 0.004). Similar findings were found with the use of image derived instrumentation (IDI) (OR = 1.27, 95 % CI 1.11-1.46, p < 0.001), robotic assisted vs. non-navigated knees (OR = 1.21, 95 % CI 1.06-1.38, p < 0.005) and no patella resurfacing (OR = 1.10, 95 % CI 1.01-1.20, p < 0.032). For lower pain scores at six months, the use of highly crosslinked polyethylene (OR = 1.12, 95 % CI 1.02-1.22, p < 0.015), cemented femoral components (OR = 1.11, 95 % CI 1.01-1.22, p < 0.024), IDI (OR = 1.20, 95 % CI 1.05-1.37, p < 0.009) or no patella resurfacing (OR = 1.10, 95 % CI 1.01-1.20, p < 0.034) were associated.

Conclusion

Utilizing a fixed bearing or robotic assistance correlated with improved OKS scores, whereas highly crosslinked polyethylene or cemented femoral components were associated with improved pain scores. At six months, the use of IDI compared to non-navigated TKA, and patellar resurfacing showed both improved OKS and pain scores.

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.

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.

Clinical effectiveness of patellar resurfacing, no resurfacing and selective resurfacing in primary total knee replacement: systematic review and meta-analysis of interventional and observational evidence

Background

Patellar resurfacing is optional during total knee replacement (TKR). Some surgeons always resurface the patella, some never resurface, and others selectively resurface. Which resurfacing strategy provides optimal outcomes is unclear. We assessed the effectiveness of patellar resurfacing, no resurfacing, and selective resurfacing in primary TKR.

Methods

A systematic review and meta-analysis was performed. MEDLINE, Embase, Web of Science, The Cochrane Library, and bibliographies were searched to November 2021 for randomised-control trials (RCTs) comparing outcomes for two or more resurfacing strategies (resurfacing, no resurfacing, or selective resurfacing) in primary TKR. Observational studies were included if limited or no RCTs existed for resurfacing comparisons. Outcomes assessed were patient reported outcome measures (PROMs), complications, and further surgery. Study-specific relative risks [RR] were aggregated using random-effects models. Quality of the evidence was assessed using GRADE.

Results

We identified 33 RCTs involving 5,540 TKRs (2,727 = resurfacing, 2,772 = no resurfacing, 41 = selective resurfacing). One trial reported on selective resurfacing. Patellar resurfacing reduced anterior knee pain compared with no resurfacing (RR = 0.65 (95% CI = 0.44–0.96)); there were no significant differences in PROMs. Resurfacing reduced the risk of revision surgery (RR = 0.63, CI = 0.42–0.94) and other complications (RR = 0.54, CI = 0.39–0.74) compared with no resurfacing. Quality of evidence ranged from high to very low. Limited observational evidence (5 studies, TKRs = 215,419) suggested selective resurfacing increased the revision risk (RR = 1.14, CI = 1.05–1.22) compared with resurfacing. Compared with no resurfacing, selective resurfacing had a higher risk of pain (RR = 1.25, CI = 1.04–1.50) and lower risk of revision (RR = 0.92, CI = 0.85–0.99).

Conclusions

Level 1 evidence supports TKR with patellar resurfacing over no resurfacing. Resurfacing has a reduced risk of anterior knee pain, revision surgery, and complications, despite PROMs being comparable. High-quality RCTs involving selective resurfacing, the most common strategy in the UK and other countries, are needed given the limited observational data suggests selective resurfacing may not be effective over other strategies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05877-7.

Patella Strength Characteristics in Cemented vs Press-fit Implants: A Biomechanical Analysis of Initial Stability

Background

Patellar resurfacing is routinely performed during total knee arthroplasty to reduce pain associated with patellofemoral osteoarthritis. With 3-dimensional ingrowth materials readily available, the present study aimed to evaluate if cemented polyethylene (CP) patellar buttons conferred higher ultimate load to failure than press-fit metal-backed (PF) buttons in axial compression.

Material and methods

Ten matched cadaveric and 20 composite patellae were resurfaced and implanted with either a PF or CP button. Biomechanical testing using an MTS machine was performed to measure the force required to generate a periprosthetic patella fracture. Mean load to failure and load to failure per 1-mm patellar thickness were compared with a paired and independent samples Students’ t-test for the cadaveric and composite patellae, respectively.

Results

The average load to failure for the matched cadaveric patellae with PF implants was significantly lower than that for patellae with CP buttons (4082.05 N vs 5898.37 N, P = .045). The average load to failure for composite patella with PF implants was significantly higher than that for composite patellae with CP implants (6004.09 N vs 4551.40 N, P = .001). The mean load to failure per 1-mm patellar thickness was also significantly higher for composite patellae with PF implants (263.80 N/mm vs 200.37 N/mm, P = .001).

Conclusion

Cadaveric patellae with cemented implants had a significantly higher ultimate load to failure in axial compression than press-fit patella. However, this result was reversed in the composite model. Exploration of biological and composite model properties could provide further insight into patellar implant selection during total knee arthroplasty.

Anterior knee pain from the evolutionary perspective

BACKGROUND

This paper describes the evolutionary changes in morphology and orientation of the PFJ using species present through our ancestry over 340 million years.

METHODS

37 specimens from the Devonian period to modern day were scanned using a 64-slice CT scanner. 3D geometries were created following routine segmentation and anatomical measurements taken from standardised bony landmarks.

RESULTS

Findings are described according to gait strategy and age. The adoption of an upright bi-pedal stance caused a dramatic change in the loading of the PFJ which has subsequently led to changes in the arrangement of the PFJ. From Devonian to Miocene periods, our sprawling and climbing ancestors possessed a broad knee with a shallow, centrally located trochlea. A more rounded knee was present from the Paleolithic period onwards in erect and bipedal gait types (aspect ratio 0.93 vs 1.2 in late Devonian), with the PFJ being placed lateral to the midline compared to the medial position in quadrapeds. The depth of the trochlea groove was maximal in the Miocene period of the African ground apes with associated acute sulcus angles in Gorilla (117°) becoming more flattened towards the modern human (138°).

CONCLUSIONS

The evolving bipedal gait lead to anteriorisation of the patellofemoral joint, flattening of the trochlea sulcus, in a more lateral, dislocation prone arrangement. Ancestral developments might help explain the variety of presentations of anterior knee pain and patellofemoral instability.

Functional Outcomes Following Total Knee Arthroplasty Without Patellar Resurfacing: A Minimum Two-Year Follow-Up Retrospective Cohort Study

This paper seeks to address the effectiveness of total knee arthroplasty (TKA) when performed without patellar resurfacing. The objective of this article is to investigate the effect of total knee arthroplasty without patellofemoral resurfacing on postoperative outcome.

All patients with degenerative knee osteoarthritis (OA) that underwent TKA without patellar resurfacing were included in the study. The clinical data of 163 patients, including 98 females and 65 males with a mean age of 63 years (range 54-78 years) were retrospectively analyzed from April 2008 to April 2011. Intraoperative cartilage degeneration according to Outerbridge classification criteria was as follows: 22 cases of grade I, 38 cases of grade II, 64 cases of grade III, 39 cases of grade IV. There were no significant differences in gender, age, and side differences between the patients at all levels (P > 0.05). The duration of tourniquet use and related complications were recorded. Knee function was assessed using the American Knee Society Scoring System (KSS) and the patellar score (PS). Patient satisfaction and knee pain were assessed by the pain visual analog scale (VAS). The evaluation was conducted using routine X-ray film to observe the position of the prosthesis and the patella. Statistical analysis used included a comparison between groups by analysis of variance (ANOVA) using the Student-Newman-Keuls (SNK) test and comparison of grade data using the rank-sum test.

The average tourniquet time was 125 minutes, with a range of 90-150 minutes. All the incisions healed with primary intention without early complications. All patients were followed for two to five years with an average of 3.6 years. At six months and at the last follow-up, the KSS and PS scores were significantly higher than those before surgery (P < 0.05). There was no significant difference between the sixth month and the last follow-up (P > 0.05). There were significant differences in preoperative KSS and PS scores between patients with different grades of cartilage degeneration (P < 0.05), but there was no significant difference at the last follow-up (P > 0.05). At the last follow-up, seven patients had persistent anterior knee pain, five patients had mild pain, and two patients had moderate pain according to the VAS assessment criteria. Patient satisfaction evaluation was as follows: 90 patients were very satisfied, 66 patients were satisfied, five patients were uncertain, and two patients were unsatisfied. There were no significant differences in satisfaction and knee pain between patients with different grades of patellofemoral degeneration (P > 0.05).

In conclusion, at six months and at the last follow-up, outcome measures for patients were significantly higher than before surgery for TKA without the use of patellar resurfacing and the majority of patients were satisfied with the outcome of the procedure. TKA continues to be a successful procedure without the use of patellar resurfacing.

Explanatory Factors for Periprosthetic Infection in Total Knee Arthroplasty

There are many studies whose results reveal possible risk factors for developing an infection after a total knee arthroplasty (TKA). The objective of this study is to analyse the risk factors that depend on the hospital and, especially, if the patellar replacement influences the appearance of periprosthetic infection. A retrospective study was performed, where data from the electronic registry of patients of people over 18 and who had undergone TKA, between the years 2015 and 2018, were reviewed. Dependent variables on the patients and the health care system were collected. The possible associations between the factors and the appearance of infection after TKA were studied using univariate and multivariate regression analyses. A total of 907 primary knee arthroplasties were included in the study. Those patients who had their patella replaced had a significantly higher risk of developing an infection (OR 2.07; 95% confidence interval 1.01–6.31). Likewise, patients who underwent surgery by surgeons with more than 10 years of experience were more than twice as likely to become infected than those operated on by younger surgeons (OR 2.64; 95%CI 1.01–6.97). Male patients were also found to be three times more likely to be infected than women (OR 2.99; 95%CI 1.32–5.74). Those interventions that were longer had a higher risk of infection. The same happened with patients who stayed in the hospital for a longer period of time. The rest of the variables did not show statistically significant results. In this study, it was found that the replacement of the patella may be a factor of infection, but it should be corroborated with randomized clinical trials. Furthermore, patients who underwent longer surgeries or those with prolonged hospital stays should be closely monitored to detect infection as soon as possible and establish the most appropriate treatment.

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.

Why are patients dissatisfied following a total knee replacement? A systematic review

BACKGROUND

Although total knee replacement (TKR) is an effective intervention for end-stage arthritis of the knee, a significant number of patients remain dissatisfied following this procedure. Our aim was to identify and assess the factors affecting patient satisfaction following a TKR.

MATERIALS AND METHODS

In accordance with the PRISMA guidelines, two reviewers searched the online databases for literature describing factors affecting patient satisfaction following a TKR. The research question and eligibility criteria were established a priori. Any clinical outcome study that described factors relating to overall satisfaction after primary TKR was included. Quality assessment for the included studies was performed by two accredited orthopaedic surgeons experienced in clinical research.

RESULTS

The systematic review identified 181 relevant articles in total. A history of mental health problems was the most frequently reported factor affecting patient satisfaction (13 reportings). When the results of the quality assessment were taken into consideration, a negative history of mental health problems, use of a mobile-bearing insert, patellar resurfacing, severe pre-operative radiological degenerative change, negative history of low back pain, no/less post-operative pain, good post-operative physical function and pre-operative expectations being met were considered to be important factors leading to better patient satisfaction following a TKR.

CONCLUSION

Surgeons performing a TKR should take these factors into consideration prior to deciding whether a patient is suitable for a TKR. Secondarily, a detailed explanation of these factors should form part of the process of informed consent to achieve better patient satisfaction following TKR. There is a great need for a unified approach to assessing satisfaction following a TKR and also the time at which satisfaction is assessed.

No difference in clinical outcome and survivorship after total knee arthroplasty with patellar resurfacing and nonresurfacing after minimum 10-year follow-up

The study aims to evaluate the clinical outcomes and surgery survivorship for over 10 years following patellar resurfacing or nonresurfacing in total knee arthroplasty (TKA) in a cohort of Chinese patients.From 1998 to 2003, 355 patients underwent primary TKA in our institute. The survivorship of TKA between the patellar resurfacing and nonresurfacing groups and the clinical outcome of Hospital for Special Surgery knee score, Western Ontario and McMaster Universities index score, patellar score, patellar related complications, and radiological results were studied at latest follow-up.There was no statistically significant difference for the Hospital for Special Surgery score, Western Ontario and McMaster Universities score, and the patellar score between the 2 groups after an average 12.4-year follow-up. Nonresurfacing group had higher anterior knee pain than the resurfacing group (13.2% vs 5.6%). The patients with rheumatoid arthritis had a 2.9-fold higher rate of patellar-related complications than did the patients with osteoarthritis. The 10-year survival rate was not significantly different between the 2 groups both for revision surgery (P = .505) and for patellar-related complication (P = .194).There was no significant difference in the long-term clinical outcome and survivorship between patellar resurfacing and nonresurfacing. Patellar nonresurfacing could be advisable during primary TKA for osteoarthritis patients. Selective patellar resurfacing for RA patients could achieve lower patellar-related complications.

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.

Routine Patellar Resurfacing During Total Knee Arthroplasty Is Not Cost-Effective in Patients Without Patellar Arthritis

BACKGROUND

Currently, the decision to resurface the patella is often made irrespective of the presence of patellar arthritis. The purpose of this study is to utilize the existing literature to assess cost-utility of routinely vs selectively resurfacing the patella.

METHODS

Prospective randomized studies of patella resurfacing vs non-resurfacing in total knee arthroplasty (TKA) were identified through literature review. Data from these studies represented probabilities of varied outcomes following TKA dependent upon patella resurfacing. Using previously validated utility scores from the McKnee modified Health Utilities Index, endpoint utility values were provided for each potential outcome.

RESULTS

Literature review yielded a total of 14 studies with 3,562 patients receiving 3,823 TKAs, of which 1,873 (49.0%) patellae were resurfaced. Persistent postoperative anterior knee pain occurred in 20.9% vs 13.2% (P < .001) and patella reoperation was performed in 3.7% vs 1.6% (P < .001) of unresurfaced and resurfaced patella, respectively. In studies excluding those with arthritic patellae, the incidence of anterior knee pain was equivalent between groups and reoperation decreased to 1.2% vs 0% (P = .06). Patella resurfacing provided marginally improved quality-adjusted life-years (QALY) for both selective and indiscriminate patella resurfacing. When including all studies, the incremental cost per QALY was $3,032. However, when analyzing only those studies with nonarthritic patellae, the incremental cost per QALY to resurface the patella increased to $183,584.

CONCLUSION

Patellar resurfacing remains a controversial issue in TKA. Utilizing data from new prospective randomized studies, this analysis finds that routinely resurfacing arthritis-free patellae in TKA are not cost-effective.

The Effect of Surgeon Preference for Selective Patellar Resurfacing on Revision Risk in Total Knee Replacement: An Instrumental Variable Analysis of 136,116 Procedures from the Australian Orthopaedic Association National Joint Replacement Registry

BACKGROUND

The optimum strategy regarding resurfacing the patella in total knee replacement (TKR) remains debated, with wide national and international variability. To minimize the confounders of a direct comparison of cases with or without resurfacing, we performed an instrumental variable analysis examining revision risk on the basis of surgeon preference for patellar resurfacing in TKR, specifically examining the subsequent patellar revision risk and all-cause revision risk among cases of surgeons preferring to perform resurfacing on a selective basis compared with those whose preference is to routinely resurface or who infrequently perform resurfacing.

METHODS

Data from the Australian Orthopaedic Association National Joint Replacement Registry from 1999 to 2016 were obtained to assess the cumulative percent revision, hazard ratio, and revision diagnoses for 3 cohorts, grouped according the surgeons' patellar-resurfacing preferences: infrequently (<10% of the time), selectively (10% to <90% of the time), or routinely (≥90% of the time). To avoid confounding from implant design or surgeon performance, only minimally stabilized TKRs using hybrid or cemented fixation and performed by surgeons performing ≥50 TKR procedures per year were included.

RESULTS

A total of 136,116 procedures were included, with patients in all 3 cohorts having similar demographics. The selectively resurfaced cohort had a higher patellar revision risk compared with the routinely resurfaced cohort, with this risk being greatest in the first 4.5 years following the primary procedure, including 306% higher in the first 1.5 years, and remaining 50% higher after 4.5 years. In a subgroup analysis, increased revision risk was observed among males, females, those <65 years of age, and those ≥65 years of age. The infrequently resurfaced cohort had the highest risk of subsequent patellar revision, up to 482% higher, as seen in the first 1.5 years after the primary procedure, compared with the routinely resurfaced cohort. Additionally, the risk of all-cause revision was 20% higher for the selectively resurfaced cohort compared with routinely resurfaced.

CONCLUSIONS

Surgeons who preferred selective resurfacing of the patella had a higher risk of patellar revision than those who had preference for routine resurfacing of the patella. Overall, a greater preference for resurfacing resulted in a lower risk of patellar revision.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Patellar complications following total knee arthroplasty: a review of the current literature

Total knee arthroplasty is a common operation for treating patients with end-stage knee osteoarthritis and generally has a good outcome. There are several complications that may necessitate revision of the implants. Patella-related complications are difficult to treat, and their consequences impact the longevity of the implanted joint and functional outcomes. In this review, we explore the current literature on patellar complications in total knee arthroplasty and identify risk factors as well as strategies that can help in preventing these complications. We present pertinent findings relating to patellar complications. They can be classified into bony or soft tissue complications and include bone loss, aseptic loosening, periprosthetic fractures, patella fracture, patellar clunk syndrome, patellofemoral instability, extensor mechanism complications, maltracking, patella baja and malrotation. We conclude that patellar complications in total knee arthroplasty are common and have significant implications for the functional outcome of total knee arthroplasty. A high index of suspicion should be maintained in order to avoid them. Implant malpositioning and other forms of intraoperative technical error are the main cause of these complications, and therefore, primary prevention is crucial. When dealing with these established problems, a clear plan of action should be formulated in advance to allow appropriate management as well as anticipation of adverse outcomes.

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.

Patellar Resurfacing in Total Knee Arthroplasty: A Cost-Effectiveness Analysis

BACKGROUND

This study estimates the cost-effectiveness of patellar resurfacing in total knee arthroplasty (TKA).

METHODS

We conducted a cost-effectiveness analysis using a decision analytic model representing a hypothetical TKA cohort, with or without patellar resurfacing, using data from the 2014 Australian Registry. The model represents 3 possible postoperative health states: (1) well, (2) patellofemoral pain, or (3) serious adverse event (any event resulting in a revision). Our effectiveness outcome was the quality-adjusted life year, from published utility scores. We estimated cost-effectiveness from a Canadian public healthcare payer perspective. Costs and quality of life were valued in 2015 United States dollars and discounted annually at 5%.

RESULTS

Our results suggest that TKA with resurfacing is cost-effective compared to nonresurfacing. Unresurfacing the patellae resulted in higher costs ($13,296.63 vs $12,917.01) and lower quality-adjusted life year (5.37 vs 6.01) at 14 years. Sensitivity analysis suggests that if rates of secondary resurfacing are <0.5%, there was no cost difference.

CONCLUSION

Over 14 years postoperative, patellar resurfacing appears to be cost-effective, due to higher revision rates for unresurfaced TKA. Although our results suggest resurfacing improves quality of life, our model is limited by the availability and validity of long-term utility outcomes reported for TKA. Our cost-effectiveness analysis showed superiority of the resurfacing compared to retention of the patella.

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.

In Vivo Three-Dimensional Patellar Mechanics: Normal Knees Compared with Domed and Anatomic Patellar Components

BACKGROUND

Patellofemoral complications are a major cause of revision surgery following total knee arthroplasty (TKA). High forces occurring at the patellofemoral articulation coupled with a small patellofemoral contact area pose substantial design challenges. In this study, the three-dimensional (3D) in vivo mechanics of domed and anatomically shaped patellar components were compared with those of native patellae.

METHODS

Ten normal knees, 10 treated with an LCS-PS (low contact stress-posterior stabilized) TKA (anatomically shaped patellar component), and 10 treated with a PFC Sigma RP-PS (press-fit condylar Sigma rotating platform-posterior stabilized) TKA (domed patellar component) were analyzed under fluoroscopic surveillance while the patient performed a weight-bearing deep knee bend from full knee extension to maximum knee flexion. Relevant bone geometries were segmented out from computed tomography (CT) scans, and computer-assisted-design (CAD) models of the implanted components were obtained from the manufacturer. Three-dimensional patellofemoral kinematics were obtained using a 3D-to-2D registration process. Contact mechanics were calculated using a distance map between the articulating patellar and femoral surfaces.

RESULTS

Both patellar component designs exhibited good rotational kinematics and tracked well within the femoral trochlea when compared with the normal patella. The contact areas in the TKA groups peaked at 60° of knee flexion (mean and standard deviation, 201 ± 63.4 mm for the LCS-PS group and 218 ± 95.4 mm for the Sigma RP-PS group), and the areas were substantially smaller than those previously reported for the normal patella. Contact points in the TKA groups stayed close to the center of the patellar components.

CONCLUSIONS

Both designs performed satisfactorily, although patellofemoral contact areas were reduced in comparison with those in the native patella.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Similar patient-reported outcomes and performance after total knee arthroplasty with or without patellar resurfacing

Background and purpose - Knee pain after total knee arthroplasty (TKA) is not uncommon. Patellar retention in TKA is one cause of postoperative knee pain, and may lead to secondary addition of a patellar component. Patellar resurfacing in TKA is controversial. Its use ranges from 2% to 90% worldwide. In this randomized study, we compared the outcome after patellar resurfacing and after no resurfacing. Patients and methods - We performed a prospective, randomized study of 74 patients with primary osteoarthritis who underwent a Triathlon CR TKA. The patients were randomized to either patellar resurfacing or no resurfacing. They filled out the VAS pain score and KOOS questionnaires preoperatively, and VAS pain, KOOS, and patient satisfaction 3, 12, and 72 months postoperatively. Physical performance tests were performed preoperatively and 3 months postoperatively. Results - We found similar scores for VAS pain, patient satisfaction, and KOOS 5 subscales at 3, 12, and 72 months postoperatively in the 2 groups. Physical performance tests 3 months postoperatively were also similar in the 2 groups. No secondary resurfacing was performed in the group with no resurfacing during the first 72 months Interpretation - Patellar resurfacing in primary Triathlon CR TKA is of no advantage regarding pain, physical performance, KOOS 5 subscales, or patient satisfaction compared to no resurfacing. None of the patients were reoperated with secondary addition of a patellar component within 6 years. According to these results, routine patellar resurfacing in primary Triathlon TKA appears to be unnecessary.

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.

Is resurfacing the patella cheaper? An economic analysis of evidence based medicine on patellar resurfacing

BACKGROUND

Primary total knee arthroplasty is a high volume procedure which is expected to grow dramatically in the near future. The decision to resurface the patella has been discussed extensively in the literature yet the financial implications of resurfacing versus not resurfacing have not been demonstrated.

METHODS

We identified all randomized controlled trials comparing patellar resurfacing to nonresurfacing in the past ten years and identified the total number of patellofemoral revision surgeries for both resurfaced and nonresurfaced patellas in each study. An expected-value decision tree analysis was created using only data from the randomized controlled trials. Actual costs collected from Medicare reimbursement rates were then applied to the model and a sensitivity analysis was performed.

RESULTS

The expected value of primary total knee arthroplasty with patellar resurfacing was $13,788.48 while a primary total knee arthroplasty without patellar resurfacing was $14,016.41 after five years. The difference represents an additional $227.92 of Medicare dollars for every primary total knee arthroplasty performed without patellar resurfacing at five years. The model remains valid as long as patellofemoral revision rates after patellar resurfacing remain below 3.54% and patellofemoral revision rates after nonresurfaced patellas remain above 0.77%.

CONCLUSIONS

While initially counterintuitive, resurfacing the patella during a primary total knee arthroplasty is the optimal financial strategy from a Medicare perspective over a mid term period.

Selective patellar resurfacing in total knee arthroplasty: a prospective, randomized, double-blind study

350 knees were evaluated in a prospective, randomized, double-blinded study of selective patellar resurfacing in primary total knee arthroplasty. Knees with exposed bone on the patellar articular surface were excluded. 327 knees were evaluated at a mean follow-up of 7.8years. 114 knees followed for greater than 10 years were analyzed separately. Satisfaction was higher in patients with a resurfaced patella. In patients followed for at least 10 years, no significant difference was found. No difference was found in KSS scores or survivorship. No complications of patellar resurfacing were identified. The vast majority of patients with remaining patellar articular cartilage do very well with total knee arthroplasty regardless of patellar resurfacing. Patient satisfaction may be slightly higher with patellar resurfacing.

Lateral patellar facetectomy and medial reefing in patients with lateral facet syndrome after patellar-retaining total knee arthroplasty

We analyzed clinical outcomes of partial lateral patellar facetectomy and medial reefing in patients with lateral patellar facet syndrome with painful patellar-retaining total knee arthroplasty. 34 patients were followed for a mean of 40 months. All 34 patients were matched with those having secondary patellar resurfacing without facetectomy. Both groups experienced significant pain relief and range of motion improvement. The facetectomy group had higher Kujala scores than those in patellar resurfacing group. Patients with facetectomy had significantly less pain postoperatively. There were significant differences in postoperative lateral patellar tilt and congruency angle in both groups. The mid-term results for LPF with medial reefing are promising to resolve pain in patients with lateral patellar facet syndrome in patellar-retaining TKA. Therapeutic level III (retrospective comparative study).

Medium-term evaluation of total knee arthroplasty without patellar replacement

Objective

To mid-term evaluate patients who were submitted to total knee arthroplasty without patellar resurfacing.

Methods

It was realized a retrospective cross-sectional study of patients who were submitted to total knee arthroplasty without patellar resurfacing. In all patients clinical examination was done based on the protocol of the Knee Society Scoring System, which assessed pain, range of motion, stability, contraction, knee alignment and function, and radiological evaluation.

Results

A total of 36 patients were evaluated. Of these, 07 were operated only on left knee, 12 only on right knee and 17 were operated bilaterally, totaling 53 knees. Ages ranged from 26 to 84 years. Of the 53 knees evaluated, 33 (62.26%) had no pain. The maximum flexion range of motion averaged 104.7°. No knee had difficulty in active extension. As to the alignment for anatomical axis twelve knees (22.64%) showed deviation between 0° and 4° varus. Thirty-nine (75.49%) knees showed pace without restriction and the femorotibial angle ranged between 3° varus and 13° valgus with an average of 5° valgus. The patellar index ranged from 0.2 to 1.1.

Conclusion

Total knee arthroplasty whitout patellar resurfacing provides good results in mid-term evaluation.

Comparison of clinical outcomes between patellar resurfacing and nonresurfacing in total knee arthroplasty: retrospective study of 130 cases

OBJECTIVE

To compare clinical outcomes between patellar resurfacing and nonresurfacing in total knee arthroplasty (TKA).

METHODS

Data from osteoarthritis patients who underwent TKA and were followed up for ≥ 9 years were analysed retrospectively. Patients were divided into two groups: patellar nonresurfacing group and patellar resurfacing group. In the nonresurfacing group, the partial lateral facet of the patella was removed, the patella was reshaped to match the trochlea of the femoral prosthesis and circumpatellar denervation was performed. In the resurfacing group, the patella was resurfaced with a cemented component. Clinical outcomes included incidence of anterior knee pain, Knee Society Score, patient satisfaction, revision rate and radiographic findings.

RESULTS

Of the 130 patients included, 71 were assigned to the nonresurfacing group and 59 to the resurfacing group. No significant between-group differences were observed for any clinical outcomes measured. The incidence of anterior knee pain was 14.1% (nonresurfacing group) and 5.1% (resurfacing group). The revision rate was 9.89% (nonresurfacing group) and 3.4% (resurfacing group).

CONCLUSION

Clinical outcomes for patellar nonresurfacing, including patelloplasty and circumpatellar denervation, are similar to those for patellar resurfacing, in TKA.

Patellar resurfacing versus nonresurfacing in total knee arthroplasty: a meta-analysis of randomised controlled trials

PURPOSE

Patella resurfacing or nonresurfacing in total knee arthroplasty remains controversial. The aim of this study was to evaluate the efficacy of patellar resurfacing through an evaluation of the current literature.

METHODS

We carried out a meta-analysis of randomised controlled trials comparing total knee arthroplasties performed with and without patellar resurfacing. Outcomes of reoperation, anterior knee pain and knee scores were analysed.

RESULTS

Fourteen trials assessing 1,725 knees were eligible. The absolute risk of reoperation was reduced by 4 % (95 % confidence interval, 2-6 %) in the patellar resurfacing arm (between-study heterogeneity, P = 0.05, I(2) = 42 %), implying that one would have to resurface 25 patellae (95 % confidence interval, 17-50 patellae) in order to prevent one reoperation. There was no difference between the two groups in terms of anterior knee pain, knee pain score, Knee Society score and knee function score. But in the studies followed up for a mean time of not less than five years, a difference was found between the two arms in Knee Society scores (RR = 2.14, 95 % confidence interval, 0.76-3.52; P = 0.002).

CONCLUSIONS

The available evidence indicates that patellar resurfacing reduces the risk of reoperation after total knee arthroplasty. Patellar resurfacing patients may make a difference in long-term follow-up (five or more 5 years) of Knee Society scores. In other aspects, the benefit of patellar resurfacing is limited. Additionally, more carefully and scientifically designed randomised controlled trials are required to further prove the claim.

The influence of patellar resurfacing on patellar kinetics and retropatellar contact characteristics

BACKGROUND

Femoropatellar complications are one of the most common problems after total knee arthroplasty (TKA). However, the question of whether to resurface the patella remains controversial. Therefore, we evaluated the kinetics and the retropatellar contact characteristics of patella resurfacing with fixed and gliding surfaces.

METHODS

Eight Thiel-embalmed cadaver knees were tested--first intact, then after TKA without patellar resurfacing, and finally with additional patellar resurfacing--while flexing the knee from 0° to 100°. We tested a fixed as well as a gliding patella surface. During the examination, quadriceps and hamstring forces were applied. The retropatellar pressure was determined with a special patella sensor, and the patellar kinetics were measured using an optical three-dimensional motion analysis system.

RESULTS

Resurfacing the patella caused a significant increase in retropatellar pressure and a significant decrease in retropatellar contact area. Using a fixed patella, the retropatellar pressure nearly quadrupled in higher flexion compared to the native patella. Furthermore, the lateral movement of the patella increased after TKA, especially after additional patellar resurfacing.

CONCLUSIONS

Resurfacing the patella routinely is not advised. When osteoarthritis of the patella is found, the gliding patella should be preferred.

Early migration of tibial components is associated with late revision: a systematic review and meta-analysis of 21,000 knee arthroplasties

PURPOSE

We performed two parallel systematic reviews and meta-analyses to determine the association between early migration of tibial components and late aseptic revision.

METHODS

One review comprised early migration data from radiostereometric analysis (RSA) studies, while the other focused on revision rates for aseptic loosening from long-term survival studies. Thresholds for acceptable and unacceptable migration were determined according to that of several national joint registries: < 5% revision at 10 years.

RESULTS

Following an elaborate literature search, 50 studies (involving 847 total knee prostheses (TKPs)) were included in the RSA review and 56 studies (20,599 TKPs) were included in the survival review. The results showed that for every mm increase in migration there was an 8% increase in revision rate, which remained after correction for age, sex, diagnosis, hospital type, continent, and study quality. Consequently, migration up to 0.5 mm was considered acceptable during the first postoperative year, while migration of 1.6 mm or more was unacceptable. TKPs with migration of between 0.5 and 1.6 mm were considered to be at risk of having revision rates higher than 5% at 10 years.

INTERPRETATION

There was a clinically relevant association between early migration of TKPs and late revision for loosening. The proposed migration thresholds can be implemented in a phased, evidence-based introduction of new types of knee prostheses, since they allow early detection of high-risk TKPs while exposing only a small number of patients.

A randomized controlled trial comparing patellar retention versus patellar resurfacing in primary total knee arthroplasty: 5-10 year follow-up

Background

The primary purpose of this randomized controlled trial (RCT) was to compare knee-specific outcomes (stiffness, pain, function) between patellar retention and resurfacing up to 10 years after primary total knee arthroplasty (TKA). Secondarily, we compared re-operation rates.

Methods

38 subjects with non-inflammatory arthritis were randomized at primary TKA surgery to receive patellar resurfacing (n = 21; Resurfaced group) or to retain their native patella (n = 17; Non-resurfaced group). Evaluations were performed preoperatively, one, five and 10 years postoperatively by an evaluator who was blinded to group allocation. Self-reported knee-specific stiffness, pain and function, the primary outcomes, were measured by the Western Ontario McMaster Osteoarthritis Index (WOMAC). Revision rate was determined at each evaluation and through hospital record review.

Results

30 (88%) and 23 (72%) of available subjects completed the five and 10-year review respectively. Knee-specific scores continued to improve for both groups over the 10-years, despite diminishing overall health with no significant group differences seen. All revisions occurred within five years of surgery (three Non-resurfaced subjects; one Resurfaced subject) (p = 0.31). Two revisions in the Non-resurfaced group were due to persistent anterior knee pain.

Conclusions

We found no differences in knee-specific results between groups at 5–10 years postoperatively. The Non-resurfaced group had two revisions due to anterior knee pain similar to rates reported in other studies. Knee-specific results provide useful postoperative information and should be used in future studies comparing patellar management strategies.

ClinicalTrials.gov identifier

NCT01500252

Patient satisfaction after total knee and hip arthroplasty

Patient satisfaction is an important outcome measurement in TKA/THA surgery. Patient satisfaction can be evaluated from 2 perspectives, determinants of satisfaction and components of satisfaction.(5) In total joint arthroplasty, improvements in satisfaction can be achieved by examining these perspectives. Patient satisfaction is one of the many PROMs used in orthopedic surgery and is an integral part of the growing sentiment to evaluate surgery from the patient's perspective as well as from the surgeon's. The importance of measuring outcomes from the patient perspective is integral to today's patient-centered models of care.

Patellar reshaping versus resurfacing in total knee arthroplasty - Results of a randomized prospective trial at a minimum of 7 years' follow-up

OBJECTIVE

To compare the results of primary total knee arthroplasty with patellar reshaping or resurfacing.

METHODS

One hundred thirty-three patients were randomized into patellar reshaping group and patellar resurfacing group. Patellar reshaping includes resecting the partial lateral facet of the patella and the osteophytes surrounding the patella, trimming the patella to match the trochlea of the femoral component. The minimum follow-up time was 7 years. The outcome was measured by anterior knee pain rate, Knee Society clinical score, and radiographs.

RESULTS

Eight patients in the reshaping group (12.5%) and 10 patients in the resurfacing group (14.7%) complained of anterior knee pain (P=0.712). Meanwhile, there were no significant differences between the two groups in terms of total Knee Society score, Knee Society pain score, Knee Society function score, as well as anterior knee pain rate.

CONCLUSIONS

With the numbers available, there was no significant difference between the groups treated with patellar reshaping or patellar resurfacing with regard to the KSS, anterior knee pain rate and radiographs. We prefer reshaping the patella to resurfacing the patella because the former preserves sufficient patellar bone stock and can easily be converted to patellar replacement if patients complain of recurrent anterior knee pain.

The effect of patellar replacement technique on patellofemoral complications and anterior knee pain

Routine patella replacement with total knee arthroplasty has not been universally adopted because of associated patellofemoral complications such as anterior knee pain (AKP). In the proposed technique, the articular surface of the lateral facet of the patella is excised to the depth of the subchondral bone, and the medial facet is then cut parallel to the anterior surface. We evaluated any correlation between various radiographic parameters and AKP in 100 consecutive fixed-bearing posterior-stabilized total knee arthroplasties. There were no cases of fracture, avascular necrosis, subluxation, dislocation, patellar baja, or overstuffing of the patella. Anterior knee pain was present in 11% of cases, and no cases were severe or disabling. There were no correlations between AKP, range of motion, patellar size and shape, and any of the radiographic parameters.

Secondary resurfacing of the patella after primary total knee arthroplasty does the anterior knee pain resolve?

Although it has been shown that the risk of anterior knee pain is greater in patients with nonresurfaced patellae, it is not exactly clear whether the pain would resolve with secondary resurfacing of the patella. Thirty-nine patients (41 knees) underwent secondary patellar resurfacing between January 2001 and January 2007. The mean age was 66 years. The mean body mass index was 29.2 kg/m(2). The average time from primary total knee arthroplasty to resurfacing procedure was 29 months. The mean follow-up was 54 months. Anterior knee pain was the indication for secondary resurfacing in all patients. Although the clinical and functional knee scores improved significantly for whole cohort, 8 patients (8 knees) were dissatisfied with the outcome of surgery. This study highlights that secondary resurfacing is not an always rewarding procedure and patients need to be consulted appropriately with regard to the outcome.

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.

Patellar resurfacing in total knee arthroplasty for osteoarthritis: a meta-analysis

PURPOSE

Whether to resurface the patella during a primary total knee arthroplasty remains a controversial issue. The aim of this study was to determine the advantages and disadvantages of patellar resurfacing during total knee arthroplasty for osteoarthritis through an evaluation of the current literature.

METHODS

A meta-analysis of randomized controlled trials comparing patellar resurfacing with nonresurfacing during total knee arthroplasties was performed. The focus of this analysis was on outcomes of reoperation, anterior knee pain and knee scores.

RESULTS

Ten trials assessing 1,003 knees were eligible. The absolute risk of reoperation was reduced by 4% (95% confidence interval, 1-7%) in the patellar resurfacing arm (between-study heterogeneity, P = 0.06, I (2) = 45%), implying that one would have to resurface 25 patellae (95% confidence interval, 14-100 patellae) in order to prevent one reoperation. Only seven trials provided adequate data of anterior knee pain for a quantitative synthesis. On the basis of those seven trials, there was no difference between the two groups in terms of anterior knee pain. Anterior knee pain after total knee arthroplasty could have multiple etiologies such as surgical factors and nonresurfaced patella is not the sole cause of this problem.

CONCLUSION

The available evidence indicates that patellar resurfacing reduce the risk of reoperation after total knee arthroplasty for osteoarthritis. Not resurfacing the patella might be considered a reasonable option, but patients must accept the increased risk of reoperation for which the quantitative evidence-based synthesis is mild. Based on the evidence provided by this study and those previously published ones, the authors do not now resurface the patella as a matter of routine for patients having a primary total knee arthroplasty for osteoarthritis.

Patellar resurfacing in total knee arthroplasty: does design matter? A meta-analysis of 7075 cases

BACKGROUND

Patellar resurfacing in total knee arthroplasty remains controversial. The aim of this study was to compare outcomes following total knee arthroplasty with patellar resurfacing with those following total knee arthroplasty without patellar resurfacing. We also sought to identify any correlation between outcomes and prosthetic design.

METHODS

Eighteen Level-I randomized controlled trials with a cumulative sample size of 7075 knees (3463 in the resurfacing group and 3612 in the non-resurfacing group) satisfied the inclusion criteria. In the primary analysis, patellar resurfacing total knee arthroplasty was compared with non-resurfacing total knee arthroplasty, with use of reoperation rates, incidence of anterior knee pain, and functional scores as outcome measures. The secondary analysis focused on comparing patella-friendly and non-patella-friendly total knee arthroplasty designs with regard to the same three outcome measures.

RESULTS

No significant differences were found between the resurfacing and non-resurfacing groups with regard to the incidence of anterior knee pain. A higher rate of reoperations was observed in the non-resurfacing group. Analysis of homogeneous data comparing patella-friendly with non-patella-friendly total knee arthroplasty designs demonstrated no differences in the incidence of reoperations.

CONCLUSIONS

No evidence was found to suggest that either patellar resurfacing or the prosthetic design affects the clinical outcome of a total knee arthroplasty. The higher incidence of reoperations in the non-resurfacing group may be attributed to the fact that secondary patellar resurfacing adds a surgical option for the treatment of anterior knee pain following total knee arthroplasty, thus artificially increasing the rate of reoperations in the non-resurfacing group.

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.

Increased bone mineral density in the non-resurfaced patella after total knee arthroplasty: a clinical and densitometric study

We report the results of a longitudinal study of 40 patients with osteoarthritis who had primary prosthetic replacement without patellar resurfacing, and were followed at 6 months postoperatively with a densitometric study and clinically at a minimum follow-up of 2 years. Densitometric analysis showed a mean preoperative density at the affected knee of 0.69 g/cm(2) (CI: 0.62-0.76), compared to 0.86 g/cm(2) (CI: 0.79-0.93) for the opposite knee (p = 0.002). In our study population, the return to load and motion to the retained patella led to a significant increase in patellar bone density as measured by densitometry studies. This observation correlated with significant improvement in knee functional score.

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.

Isolated resurfacing of the previously unresurfaced patella total knee arthroplasty

Postoperative anterior knee pain can be challenging after primary total knee arthroplasty. Isolated patellar resurfacing may provide symptomatic improvement in those patients with an unresurfaced patella. Seventeen isolated patellar resurfacing procedures were performed. Patient outcomes were evaluated using the Knee Society clinical and roentgenographic evaluation systems. Continued symptomatology and overall patient satisfaction were also analyzed. No revisions have been necessary at 47 months of follow-up. Overall, Knee Society knee scores and knee function scores significantly improved. Eight patients (53%) are asymptomatic and were satisfied with the procedure, whereas 7 patients (47%) continue to have anterior knee pain and are unsatisfied. Isolated patellar resurfacing for anterior knee pain in total knee arthroplasty with an unresurfaced patella has a low morbidity and revision rate but may not provide patients with predictable symptomatic improvement.

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.