Bilateral simultaneous total knee arthroplasty with and without patellar resurfacing. A prospective single surgeon series with a minimum follow-up of 7 years.

BACKGROUND: Total knee arthroplasty (TKA) is the most effective treatment for end-stage adult knee osteoarthritis, but it has been reported that patient satisfaction may vary. A malfunction of the patellofemoral joint may produce anterior knee pain (AKP) for several reasons. While some surgeons systematically resurface the patella despite the risk of potential complications such as fracture, loosening, or wear of the patella, others prefer to preserve it to reduce AKP and revision rates. This study aimed to evaluate whether patellar resurfacing had better clinical and functional outcomes, complications, and revision rates in patients undergoing simultaneous bilateral total knee arthroplasty. METHODS: We conducted a prospective cohort study, including patients who underwent bilateral simultaneous TKA in which the patella was replaced in one knee and preserved in the other, with a minimum follow-up of 7 years. We assessed clinical and functional outcomes with the Knee Society Score (KSS) and Visual Analogue Scale (VAS); complications and revision rates were also registered. RESULTS: The final series consisted of 43 patients with 86 knee arthroplasties. After a mean of 7.6 years of follow-up, no significant differences were found regarding KSS (clinical: 82.8 ± 7.4 versus 83.2 ± 3.4, p = 0.92; functional 89.1 ± 8.2: versus 90.4 ± 6.8; p = 0.99), VAS (2.0 ± 0.9 versus 1.8 ± 1.0; p = 0.84), complications (10.5% versus 8.1%; p = 0.57), or revision rates (2.3% versus 2.3%; p = 0.99) when comparing patellar resurfacing versus retention. CONCLUSION: In the context of total knee arthroplasty, patellar replacement did not demonstrate statistically significant differences concerning patellar retention in clinical nor functional outcomes, AKP, complications, or revision rates after a minimum of 7 years of follow-up.

Secondary Patellar Resurfacing Following Primary Unresurfaced Total Knee Arthroplasty: Beware of the Incidence of Late Patellar Erosion.

BACKGROUND: The primary aim of this study was to evaluate secondary patellar resurfacing (SPR) indications and rates in a single-surgeon series utilizing a modern TKA design and additionally, to review the functional outcomes of patients after undergoing SPR. METHODS: A retrospective review of a prospectively collected institutional database was performed. All patients undergoing primary TKA by a single surgeon between 2013 and 2021 were included. During this time, the senior surgeon resurfaced the patella selectively. Patients were divided into the primary resurfaced (PR) and the primary unresurfaced (UR). All patients undergoing SPR in the UR group were identified, their radiographs reviewed, and their clinical outcomes assessed. During the study period, 1,511 TKAs were performed, with 73.1% (1,105 TKAs) being unresurfaced. RESULTS: The all-cause revision rate was 1.2% in the PR group and 3.6% in the UR group. The rate of SPR in the UR group was 2.0% (22 of 1,105 TKAs). No patient in the PR group underwent revision surgery for a patellar complication. The mean age at primary TKA for those undergoing SPR was 65 years (range, 50 to 78). The average time for SPR from primary TKA was 3.4 years (range, 1.1 to 8.8). Postoperative radiographic progression of patellar erosion, in combination with new onset anterior knee pain, was the indication for SPR in 14 of the 22 (63.7%) SPR cases. After SPR, the Western Ontario and McMaster University Osteoarthritis Index score (P < .001) and Knee Society Score (P < .001) improved from pre-SPR. CONCLUSIONS: Secondary patellar resurfacing (SPR) was the most common (55%) reason for revision surgery after primary UR TKA in this series. An SPR improved clinical outcomes in symptomatic patients. Surgeons should consider patellar resurfacing for all patients undergoing primary TKA to reduce the burden of revision surgery post-TKA. Additionally, the paradigm that late SPR does not improve clinical outcomes needs to be revisited.

The Fate of Unresurfaced Patellae in Contemporary Total Knee Arthroplasty: Early to Midterm Results.

BACKGROUND: Leaving the patella unresurfaced in total knee arthroplasty (TKA) has increased significantly over the past decade in the United States, likely due to modern patella-friendly implants, complications with resurfacing, and the knowledge that historical studies were scientifically confounded. This study evaluated revision-free survivorship out to 8.5 years in a cohort of contemporary primary TKAs with patella-friendly femoral components and unresurfaced patellae. METHODS: A total of 1,053 consecutive primary TKAs with unresurfaced patellae were retrospectively reviewed. A selective patellar nonresurfacing protocol was used for all cases. Kaplan-Meier survivorship estimates were calculated based on patellar revision and the latest follow-up. An aggressive lateral patellar facetectomy was performed in 78% (823 of 1,053) of cases. The cohort was 62% women and 43% American Society of Anesthesiologists physical status classification I or II with a mean age and body mass index of 65 years (range, 35 to 94) and 35 kg/m2 (range, 18 to 65), respectively. RESULTS: A total of 4 (0.4%, 4 of 1,053) unresurfaced patellae were revised. Three were resurfaced as part of other procedures: 2 for global instability and one for aseptic loosening at a mean of 1.6 years; and one patella was resurfaced by an outside surgeon for unexplained pain. The all-cause revision-free survivorship estimate specifically related to the patella was 98.9% (95% confidence interval, 98 to 100) out to 8.5 years. No significant difference in survivorship was related to patellae with or without a lateral patellar facetectomy (99.5 versus 98.1%, P ≥ .191); however, 3 of 4 patellar revisions occurred in TKAs without a lateral patellar facetectomy (P = .035). CONCLUSIONS: The results of this study demonstrate excellent revision-free survivorship related to unresurfaced patellae, particularly when a lateral facetectomy was performed. These early to midterm results using modern patella-friendly femoral components are promising and comparable to resurfaced patellae in the literature. LEVEL OF EVIDENCE: IV.

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.

When to Do Selective Patellar Resurfacing in Total Knee Arthroplasty: A Decision-Making Algorithm Based on Pre-operative and Intra-operative Findings.

Background: Persistent anterior knee pain post total knee arthroplasty (TKA) is a significant cause of patient dissatisfaction. Selective patellar resurfacing is commonly practiced for primary total knee replacement (TKR) but there is a paucity in literature regarding its decision making. Study Objective: This study aims to develop a decision-making algorithm for selective patellar resurfacing using Hospital for Special Surgery Patello-femoral Assessment score (HSS PFA score), weight-bearing patellofemoral X-ray, and intraoperative cartilage wear assessment based on the Outerbridge classification. Materials and Methods: This prospective study enrolled 65 patients, assessing preoperative factors including HSS PFA score and Baldini view radiography. Intraoperative cartilage wear was categorized using the Outerbridge classification. Preoperative findings were correlated with intraoperative outcomes through statistical analysis, leading to the development of a predictive algorithm. The efficiency of algorithm was assessed at 3-year follow-up using HSS PFA score. Results: A significant negative correlation (r = - 0.272, p = 0.029) was observed between HSS PFA score and cartilage wear. However, no significant relationships were established between HSS PFA score and Baldini view observations, including radiological tilt (p = 0.517) and displacement (p = 0.277). Intraoperative cartilage wear versus patellar tilt (p = 0.65) and displacement (p = 0.837) also yielded non-significant results. Three-year follow-up examinations revealed no complications and significant HSS PFA score improvements in all patients. Conclusion: The requirement for patellar resurfacing can be predicted using a combination of preoperative parameter such as HSS PFA score and the intra-operative cartilage wear. We put forward an algorithm based on above findings to aid in the decision making.

To resurface or not to resurface? Investigating the impact of patellar resurfacing on anterior knee pain in rheumatoid arthritis patients undergoing total knee replacement.

BACKGROUND: Routine patellar resurfacing is a controversial issue in total knee replacement (TKR), especially for rheumatoid arthritis (RA). Anterior knee pain (AKP) is a common complaint after TKR that may be related to patellofemoral joint condition. The aim of this study was to investigate the prevalence and factors associated with AKP after TKR for RA compared between non-resurfaced patella (NRP) and resurfaced patella (RP). METHODS: This retrospective study included RA patients who underwent TKR at our institute from 2002 to 2019. All included patients had at least 1 year of follow up. Patients were divided into the NRP and RP groups. At the last follow up visit, the prevalence of AKP, and the severity of AKP, including visual analogue pain score (VAPS) and Kujala score, were compared between groups. Univariate and multivariate logistic regression analysis was performed to identify independent predictors of AKP. RESULTS: A total of 141 RA patients (median age: 60 years, 90% female, 219 knees) were included. There was no significant difference in AKP between the NRP and RP groups (12.7% vs. 7.3%, P = 0.185). Regarding AKP severity, there was no significant difference in VAPS or Kujala score between groups (P = 0.147 and P = 0.067, respectively). No independent predictors of AKP were identified. CONCLUSION: Although patellar resurfacing is recommended in TKR for RA, this study found no significant difference in prevalence of AKP, VAPS and Kujala score between those with and without patellar resurfacing during TKR.

Resurfacing Versus Non-resurfacing Patella in Total Knee Replacement: When and What to Choose.

INTRODUCTION: The opinion on the necessity of patella resurfacing has been deeply divided in the scientific community. There are three approaches to the management of the patella in total knee arthroplasty (TKA). The first method involves always resurfacing the patella, the second method involves never resurfacing it, and the third method involves resurfacing the patella only under specific circumstances. Different data support each of these strategies, but no consensus on the best management has been reached. METHODS: This is a retrospective study of 106 cases of TKA (including 29 resurfaced patellas and 77 non-resurfaced patellas), over 5 years, at the Trauma-Orthopedics Department of the Cheikh Khalifa International University Hospital, Mohammed VI University of Health Sciences, Casablanca, Morocco. Our objective is to conduct a comparative study between TKA with patella resurfacing and those without resurfacing, by analyzing the functional and radiological results obtained after the operation, to show each technique's advantages and disadvantages. RESULTS: The average age of our patients was 65 years with extremes ranging from 46 to 80 years. There was a clear female predominance with a sex ratio of 0.2. The left side was predominantly affected. Primary gonarthrosis was the main diagnosis. Our results showed no significant difference between the two groups in terms of patient satisfaction and Knee Society Score (KSS). Nevertheless, complications generated by resurfacing, such as infection, anterior pain, stiffness, and loosening of the patellar component, as well as additional costs and increased operative time, were observed. In the majority of meta-analyses, there was no discernible difference in clinical and functional results between the resurfaced and non-resurfaced groups, suggesting that patellar resurfacing is not beneficial and, therefore, unnecessary. CONCLUSION: It appears that regular resurfacing is not necessary. However, there is agreement that resurfacing the patella is the best course of action for patients with inflammatory arthropathy, considerable patella malalignment, and severe patellofemoral osteoarthritis. There are arguments in favor of each of the patella resurfacing techniques, but none of them are particularly compelling, each of these strategies has its advantages and should not be considered bad. The final decision, therefore, rests on each surgeon's practice, training, and experience.

Anterior knee pain and sit-up tests predicts patients' satisfaction and improvement in quality of life after anterior stabilized total knee replacement without patellar resurfacing.

PURPOSE: The purpose of this study was to assess patient satisfaction and identify risk factors for dissatisfaction after anterior stabilised conventional total knee arthroplasty (TKA) without patellar resurfacing, using the Goodman score. METHODS: We conducted a cross-sectional study using data from our institutional database from 1 January 2018 to 1 March 2021. Patients who underwent TKA with the Vanguard® Cruciate Retaining Anterior Stabilized Knee System (Zimmer Biomet, Warsaw, Indiana, USA) without patellar replacement were included. Patients with other bearing surfaces (posterior stabilised or medial congruent) or diagnosed with infection or instability were excluded. Patients' reported outcomes, body mass index (BMI), passive range of motion, the timed up-and-go test, sit-up test, and algometry were assessed. Patients were also asked if they had anterior knee pain. Satisfaction was assessed using the Goodman scale, and logistic multivariate regression was used to identify variables associated with dissatisfaction and perceived improvement in quality of life. RESULTS: A total of 131 TKA patients were included in the study. The median satisfaction score was 100 (interquartile range [IQR], 87.5 to 100), with the 75-point threshold at the 90th percentile according to Section A of Goodman. Section B of Goodman showed that 113 TKA patients (86.26%) reported "great improvement" or "more than I ever dreamed." Multivariate logistic regression revealed that anterior knee pain (OR 5.16, 95% CI 1.24 to 21.39), the sit-up test (OR 0.63, 95% CI 0.49 to 0.81), and BMI (OR 0.84, 95% CI 0.70 to 0.99) were significantly associated with patient dissatisfaction and a worse perceived improvement in quality of life. The receiver operating characteristics curve for the models had areas under the curve of 0.83 (95% CI 0.69 to 0.97) and 0.82 (95% CI 0.70 to 0.94), respectively. CONCLUSION: Anterior stabilised TKA without patellar resurfacing can achieve 90% satisfaction and 86% improvement in quality of life. To improve these results, it is essential to prevent and treat anterior knee pain and enhance quadriceps strength. LEVEL OF EVIDENCE: Level III (retrospective cohort study).

Patellar resurfacing and kneeling ability after total knee arthroplasty: a systematic review.

BACKGROUND: Difficulty kneeling following total knee arthroplasty (TKA) remains highly prevalent, and has cultural, social, and occupational implications. With no clear evidence of superiority, whether or not to resurface the patella remains debatable. This systematic review examined whether resurfacing the patella (PR) or not (NPR) influences kneeling ability following TKA. METHODS: This systematic review was conducted by following PRISMA guidelines. Three electronic databases were searched utilizing a search strategy developed with the aid of a department librarian. Study quality was assessed using MINROS criteria. Article screening, methodological quality assessment and data extraction were performed by two independent authors, and a third senior author was consulted if consensus was not reached. RESULTS: A total of 459 records were identified, with eight studies included in the final analysis, and all deemed to be level III evidence. The average MINORS score was 16.5 for comparative studies and 10.5 for non-comparative studies. The total number of patients was 24,342, with a mean age of 67.6 years. Kneeling ability was predominantly measured as a patient-reported outcome measure (PROM), with two studies also including an objective assessment. Two studies demonstrated a statistically significant link between PR and kneeling, with one demonstrating improved kneeling ability with PR and the other reporting the opposite. Other potential factors associated with kneeling included gender, postoperative flexion, and body mass index (BMI). Re-operation rates were significantly higher in the NPR cohort whereas PR cohorts had higher Feller scores, patient-reported limp and patellar apprehension. CONCLUSION: Despite its importance to patients, kneeling remains not only under-reported but also ill-defined in the literature, with no clear consensus regarding the optimum outcome assessment tool. Conflicting evidence remains as to whether PR influences kneeling ability, and to clarify the situation, large prospective randomized studies are required.

Systematic lateral retinacular release does not reduce anterior knee pain after total knee arthroplasty with patellar resurfacing.

PURPOSE: The aim of this study was to assess the effect of systematic lateral retinacular release (LRR) on anterior knee pain (AKP), as well as its impact on the functional and radiological outcomes after total knee arthroplasty (TKA) with patellar resurfacing. METHODS: A prospective randomized study was designed. It included patients scheduled for a TKA procedure with patellar resurfacing, who were recruited and randomized into either the LRR group or the non-release group. 198 patients were included in the final analysis. The pressure pain threshold (PPT) assessed by pressure algometry (PA), the visual analogue scale (VAS), Feller's patellar score, the Knee Society Score (KSS), patellar height, and patellar tilt were recorded both preoperatively and at the 1-year follow-up. The Mann-Whitney U test was performed to determine comparisons between both groups as well as to determine differences' intragroup. RESULTS: Relative to the clinical variables and scores, no difference was detected between the two groups at the 1-year follow-up (p = n.s.). However, there was a slight difference in patellar tilt (0.1º vs. 1.4º, p = 0.044), with higher tilt values in the non-release group. There was no difference in terms of improvement in the clinical and radiological scores and variables recorded between the two groups (p = n.s.). CONCLUSION: LRR in primary TKA with patellar resurfacing does not show an improvement in AKP and functional outcomes over patellar resurfacing without release. LEVEL OF EVIDENCE: I.

Higher failure rate of secondary patellar resurfacing following bicompartmental knee arthroplasty.

INTRODUCTION: The role of secondary patellar resurfacing (SPR) in anterior knee pain (AKP) is still debated in literature. A regional arthroplasty registry was investigated, aiming to: (1) assess the survival rate of SPR; and (2) compare SPR to tricompartmental TKA. MATERIALS AND METHODS: The regional arthroplasty registry RIPO was investigated about all SPRs performed after bicompartmental arthroplasty. The survival rates and the reasons for revision were assessed as any other factor that could have influenced implants failure. SPR survivorship was compared to tricompartmental TKAs. RESULTS: 406 SPRs performed after bicompartmental arthroplasty were analyzed. The survival rates were 80.6% (CI 95% 75.9-84.5) at 5 years and 77.6% (CI 95% 72.4-82) at 7 years. Half of the SPRs was performed 0.9-2.4 years after the index bicompartmental arthroplasty. SPR achieved lower survival than tricompartmental TKA (80.6% vs 96.7%, p < 0.001), with an adjusted hazard ratio for failure of 5.5 (CI 95% 4.2-7.1, p < 0.001). SPRs performed within 2 years after primary implant had a significantly higher rates of failure when compared to tricompartmental TKA (HR: 6.4, CI 95% 4.8-8.4, p < 0.001). CONCLUSION: SPR after bicompartmental knee arthroplasty showed modest 5- and 7-year survival rates, worse than primary tricompartmental TKA. When SPRs are performed within 2 years after primary arthroplasty, a significant higher risk of failure should be expected, highlighting than appropriate pre-operative work-up and patient selection is crucial for SPR successful outcome. LEVEL OF EVIDENCE: III, therapeutic study.

Do we need to restore patellar thickness after total knee arthroplasty with patellar resurfacing?

PURPOSE: The aim of this study was to investigate whether increased patellar thickness after resurfacing decreased knee flexion angle and had any effect on functional outcomes comparing with patellar thickness restoration (patelloplasty) in patients undergoing primary total knee arthroplasty (TKA) or not. METHODS: We retrospectively reviewed 220 patients undergoing primary TKA: 110 patients undergoing patelloplasty and 110 patients received overstuffed patellar resurfacing using subchondral bone cut at lateral facet technique were recruited. The mean increase in patellar thickness after resurfacing equal to 2 ± 1.2 mm. The outcomes were postoperative knee flexion angle and modified Western Ontario and McMaster University Osteoarthritis Index (WOMAC) score at minimum 2 year after surgery. RESULTS: The mean postoperative knee flexion angles were similar between overstuffed resurfacing group and patelloplasty group (132 ± 7° vs. 134 ± 8°, 95% confidence interval [CI] - 6.9-1.8°, p = 0.1). The mean increase in postoperative knee flexion was 13° in both groups (p = 0.94). The mean change of overall modified WOMAC score was also similar between the two groups (42 ± 12 vs. 39 ± 9 points, 95% CI - 1.7-9.4 points, p = 0.17). CONCLUSION: This study demonstrated that increased patellar thickness has no effect on postoperative knee flexion angle and functional outcomes in TKA. The finding clarified the misunderstanding principle of native patellar thickness restoration after resurfacing which had made many surgeons to refrain from resurfacing especially in patient who had thin patella.

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.

Significantly Worse Fixation of Cemented Patellar Components on Multiacquisition Variable-Resonance Image Combination Magnetic Resonance Imaging Compared to Femoral and Tibial Components: A Cause for Concern?

BACKGROUND: The etiology of anterior knee pain after total knee arthroplasty (TKA) remains unclear. Few studies have examined patellar fixation quality. The purpose of the present study was to evaluate the patellar cement-bone interface after TKA on magnetic resonance imaging (MRI) and to correlate the patella fixation grade with the incidence of anterior knee pain. METHODS: We retrospectively reviewed 279 knees undergoing metal artifact reduction MRI for either anterior or generalized knee pain at least 6 months after cemented, posterior-stabilized TKA with patellar resurfacing with one implant manufacturer. MRI cement-bone interfaces and percent-integration of the patella, femur, and tibia were assessed by a fellowship-trained senior musculoskeletal radiologist. The grade and character of the patella interface were compared to the femur and tibia. Regression analyses were used to determine the association between patella integration with anterior knee pain. RESULTS: There were more patellar components with ≥75% zones of fibrous tissue (50%) compared to the femur (18%) or tibia (5%) (P < .001). There were a greater number of patellar implants with poor cement integration (18%) compared to the femur (1%) or tibia (1%) (P < .001). MRI findings showed more evidence of patellar component loosening (8%) compared to the femur (1%) or tibia (1%) (P < .001). Anterior knee pain was correlated with worse patella cement integration (P = .01), with women predicted to have better integration (P < .001). CONCLUSION: The quality of the patellar cement-bone interface after TKA is worse compared to the femoral or tibial component interface. Poor patellar cement-bone interface may be a source of anterior knee pain after TKA, but further investigation is required.

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.

Selective Patella Resurfacing in Contemporary Cruciate Retaining and Substituting Total Knee Arthroplasty: A Matched Cohort Analysis.

BACKGROUND: Leaving the patella unresurfaced in total knee arthroplasty (TKA) is increasing due to modern patella-friendly implants, awareness that complications are not uncommon with resurfacing, and knowledge that historical studies were scientifically confounded. This study examined the effect of selective patellar resurfacing on patient-reported outcome measures (PROMs) using modern implants and techniques in cohorts rigorously matched for demographics and osteoarthritis severity. METHODS: A total of 166 TKAs performed without patellar resurfacing were case-control matched to 166 TKAs with patella resurfacing. Case-control matching was based on demographics, American Society of Anesthesiology Physical Status, comorbidities, and osteoarthritis severity. No significant differences were observed between cohorts for demographics (P ≥ .347), comorbidities (P ≥ .443), or radiographic osteoarthritis severity (P ≥ .078). Radiographic alignment and prospectively collected PROMs were evaluated preoperatively and at latest clinical follow-up. RESULTS: Preoperatively, patellar tilt was less for the unresurfaced patella group (3 versus 4°, P = .003); however, postoperative patellar tilt was not different (3 versus 3°, P = .225). At a mean of 2.1 years follow-up (range, 1 to 7), University of California Los Angeles Activity Level was significantly higher for the unresurfaced patella group (6.3 versus 5.5, P = .002), but the mean group difference did not reach a minimal clinically important difference. There were no other significant differences in PROMs or reoperation rates between cohorts (P ≥ .135). CONCLUSION: In contemporary cruciate retaining and substituting TKA designs, not resurfacing the patella in select patients may achieve comparable PROMs and re-operation rates; and potentially greater activity level compared to patella resurfacing at early follow-up. LEVEL OF EVIDENCE: III.

A Prospective Comparative Study of the Functional Outcomes of Patellar Resurfacing Versus Non-resurfacing in Patients Undergoing Total Knee Arthroplasty.

Background and objective Total knee arthroplasty (TKA) is a highly successful surgical procedure. However, there is a lack of consensus about whether to resurface the patella or not. This study was aimed at evaluating the outcome of patellar resurfacing in terms of a decrease in the incidence of anterior knee pain after TKA and assessing whether patellar resurfacing is beneficial in improving functional outcomes. Materials and methods This prospective comparative study included 100 patients undergoing TKA who were randomly allotted to the patellar resurfacing or non-resurfacing group. Functional evaluation was done based on the Knee Society Score, and the pain was evaluated by the visual analogue scale (VAS) preoperatively and after one year. Results There was a significant improvement in the Knee Society scores as well as the pain scores in both groups postoperatively. The patellar resurfacing group showed statistically significant improvement as compared to the non-resurfacing group in the Knee Society clinical and functional scores as well as the VAS at the end of one year. Conclusion Patellar resurfacing during TKA provides better clinical and functional outcomes as well as more relief from anterior knee pain as compared to non-resurfacing of the patella.

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.

Comparison of Clinical Outcomes after Total Knee Arthroplasty with and without Patellar Resurfacing in the Same Patients.

Background: Patellar resurfacing is performed in total knee arthroplasty (TKA) to improve pain in the anterior compartment of the knee joint and to restore proper coordination and movement of the patellofemoral joint. The purpose of this study was to analyze differences in clinical outcomes according to patellar resurfacing in patients who underwent bilateral TKA. Methods: Forty-three patients who underwent bilateral primary TKA with patellar resurfacing on one side only were included. Patellar resurfacing was performed selectively according to the status of the patella cartilage surface. Knee Society score (knee and function), Feller score, Kujala score, and Samsung Medical Center (SMC) score (pain and function) were evaluated. Results: There were no significant differences in Knee Society pain and function scores, Feller score, Kujala score, and SMC pain and function scores according to patellar resurfacing. On the comparison of SMC scores, there was no difference except for two questions. Conclusions: It is advisable not to perform resurfacing on normal patellae. However, in order to apply this result to damaged patellae, comparative studies between resurfaced patellae and damaged patellae are needed.

Does the degree of intraoperatively identified cartilage loss affect the outcomes of primary total knee arthroplasty without patella resurfacing? A prospective comparative cohort study.

PURPOSE: The aim of this study was to investigate whether the degree of patellar cartilage loss confirmed during index surgery affects the clinical and radiologic outcomes of total knee arthroplasty (TKA) performed without patellar resurfacing. METHODS: We prospectively divided 2012 patients with a minimum follow-up of 12 months into two groups according to intraoperatively graded cartilage lesions graded using the International Cartilage Repair Society (ICRS) system: group 1, grades 0‒2 (n = 110); group 2, grades 3‒4 (n = 102). Relevant locations, such as medial, lateral, or both facets of the patella, were also assessed. Clinical outcomes were assessed using the Western Ontario and McMaster Universities Osteoarthritis Index, Feller's patella score, and Kujala anterior knee pain score. Radiographic outcomes included patellar tilt angle and lateral patellar shift on Merchant's view. RESULTS: Clinical and radiographic outcomes were not significantly different between the two groups. No patient underwent secondary patellar resurfacing. Although the lateral facet was significantly more involved, there were no significant differences in outcomes. CONCLUSIONS: The degree of intraoperatively identified patellar cartilage loss did not affect the short-term outcomes following primary TKA without patellar resurfacing. Level of evidence II: Prospective comparative study.