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

Reverse fragility index comparing rates of reoperation in total knee arthroplasty with and without patellar resurfacing: a systematic review of randomized controlled trials

BACKGROUND

Patellar resurfacing during total knee arthroplasty (TKA) is debated. The reverse fragility index (RFI1) assesses study neutrality by determining the minimum number of events needed to change non-significant results, significant. This study determined the RFI for studies showing no difference in reoperation between TKAs with and without resurfacing.

METHODS

A systematic review of PubMed, Embase, and Web of Science databases was conducted to identify randomized controlled trials (RCT) showing no difference in reoperation rates between TKAs with and without patellar resurfacing. The number of reoperations and the number of patients lost to follow-up were included. The RFI was calculated for reoperation rate of each study with a threshold of P < 0.05.

RESULTS

Nineteen RCTs with 3,804 TKAs were included, 1,813 of which resurfaced the patella. The median (interquartile range [IQR2]) reoperation rate was 4.4% (0-9.1%) in resurfaced patellae, and 4.5% (0-8.3%) in retained patellae. The median RFI was five, indicating that only five patients would need the opposite outcome for the difference in reoperation rate to become significant. The median (IQR) loss to follow-up was eight (3-20) patients, and 63.2% (12 of 19) of studies had loss that exceeded their RFI.

CONCLUSION

Most RCTs showing no difference in reoperation rate between TKAs with or without patellar resurfacing are statistically fragile. Difference in rates can become significant with the reversal of only a few outcomes, and this number was less than a study's loss to follow-up in most studies.

Functional outcome and cost effectiveness of patellar resurfacing and non-resurfacing in total knee arthroplasty: systematic review and meta-analysis

BACKGROUND

Total knee arthroplasty (TKA) is rising globally, with patellar management impacting outcomes. Resurfacing reduces pain and revision rates but poses complications, while non-resurfacing lowers costs but risks persistent pain. This study updates previous meta-analyses by comparing the functional and economic outcomes of both approaches.

METHODS

This systematic review and meta-analysis followed PRISMA guidelines. Studies comparing patellar resurfacing and non-resurfacing in TKA with functional outcomes in adults were included. Five databases were searched until February 6, 2024. Two authors independently extracted data and assessed risk of bias. Any disagreements were resolved by a third author. Statistical analysis used a random-effects model, reporting mean differences (MD) and odds ratios (OR) with 95% CI. Sensitivity and subgroup analyses were performed to assess heterogeneity and reliability.

RESULTS

A total of 49 studies (34 RCTs, 15 observational) were included from 963 screened records. Analysis of 22 studies found no significant difference in Knee Society Score (KSS) function between resurfacing and non-resurfacing (MD 2.03; 95% CI 0.58-3.48; p = 0.59, I2 = 53%). Resurfacing significantly reduced anterior knee pain (OR 0.61; 95% CI 0.42-0.87; p = 0.007, I2 = 70%). However, no significant differences were observed in pain scale, range of motion (ROM), or Oxford Knee Score. Three studies assessed economic outcomes using Incremental Net Benefit (INB) and Incremental Cost-Effectiveness Ratio (ICER) showed no significant cost-effectiveness.

CONCLUSIONS

Patellar resurfacing in TKA significantly reduces anterior knee pain but shows no advantage in KSS function, pain scale, Oxford Knee Score, ROM, or cost-effectiveness. Surgical decisions should be individualized to optimize patient outcomes.

SPECT/CT and triple-phase bone scan: A valuable diagnostic approach for identifying indications for secondary patellar resurfacing in patients with unexplained anterior knee pain post-TKA

OBJECTIVE

The efficacy of secondary patellar resurfacing (SPR) in alleviating anterior knee pain (AKP) following total knee arthroplasty (TKA) remains uncertain. The purpose of this study was to assess the suitability of SPR using single photon emission computed tomography/computed tomography (SPECT/CT) in conjunction with triple-phase bone scan (TPBS).

METHODS

We performed a retrospective analysis on a prospectively-enrolled cohort of patients suffering from AKP in the context of TKA. In this cohort, we identified a subset of 17 patients (involving 18 knees), who had unexplained AKP and were potential candidates for secondary patellar resurfacing (SPR). The candidates for SPR were designated the experimental group, and subjects receiving other forms of treatment were referred to as the Control group. The selection for these treatment options was based on the findings from SPECT/CT and triple-phase bone scan (TPBS). Data collection spanned from preoperative to postoperative follow-up periods and encompassed basic demographics, preoperative findings of SPECT/CT plus TPBS, and Knee Society Score (KSS).

RESULTS

SPECT/CT and TPBS revealed focal radionuclide concentration in the patella in 12 patients (13 knees) and in other locations in 5 patients (5 knees) with unexplained AKP, complementing the findings from medical history and physical examinations. The Experimental group showed signs of patellar maltracking or early-stage patellofemoral osteoarthritis (OA) following TKA and received SPR treatment. Postoperatively, the objective knee indicators score was significantly higher than preoperative scores (88.46 ± 5.77 vs. 76.38 ± 7.64, P < 0.05). Similarly, the functional activities score was significantly improved postoperatively (74.31 ± 6.68 vs. 50.46 ± 9.01, P < 0.05). Patient satisfaction score was substantially elevated after SPR (33.38 ± 2.87 vs. 17.08 ± 5.69, P < 0.05). The control group mainly included patients who experienced loosening, periprosthetic joint infection (PJI), or instability. These patients received revision surgeries tailored to their individual pathologies and postoperative follow-ups showed favorable outcomes.

CONCLUSIONS

SPECT/CT in combination with TPBS may serve as a valuable tool for assessing the suitability of SPR for the post-TKA management of unexplained AKP. Video Abstract.

Is Patella Resurfacing Associated With Postoperative Extensor Mechanism Disruption After Total Knee Arthroplasty? A Systematic Review and Meta-Analysis

BACKGROUND

Patella resurfacing in total knee arthroplasty (TKA) involves surgical manipulation of the extensor mechanism, which can weaken or devascularize the patellar bone, quadriceps, and patellar tendon. Patella resurfacing may, in theory, increase the risk of postoperative extensor mechanism disruption (EMD).

METHODS

We systematically searched the Cochrane, Embase, and PubMed databases to identify randomized controlled trials that reported the overall incidence of complications and surgery for EMD for resurfaced and unresurfaced patellae in patients who underwent primary TKA with a 2-year follow-up. There were nine studies included in the meta-analysis, representing 1,569 patients, 773 of whom (49%) underwent patella resurfacing. Study selection was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A common-effects model was used to calculate the pooled effects as log odds ratios (ORs) and 95% confidence intervals (CIs). P < 0.05 was considered significant.

RESULTS

The unadjusted incidence of postoperative patellar fracture was equivalent for patients who did not have patella resurfacing (0.26%) and for those who had resurfacing (0.38%) (P = 0.51). Postoperative patellar tendon tears were not reported in any patients. Quadriceps tendon tears were also uncommon, with one instance occurring in the unresurfaced group (0.13%) and one instance in the resurfaced group (0.13%) (P = 0.74). Meta-analysis revealed no significant association between patella resurfacing and sustaining any EMD-related complication (OR 0.22, 95% CI: -1.24 to 0.80) or requiring surgery for EMD (OR 0.22, 95% CI: -0.92 to 1.36).

CONCLUSIONS

In this large patient sample, the 2-year incidence of EMD-related complications after TKA was low. However, a meta-analysis of the pooled data suggests that patella resurfacing in TKA is not associated with the incidence of postoperative EMD-related complications or surgery for EMD.

LEVEL OF EVIDENCE

III.

Leaving the Patella Unresurfaced Does Not Increase the Risk of Short-Term Revision Following Total Knee Arthroplasty: An Analysis from the American Joint Replacement Registry

The benefit of patellar resurfacing in total knee arthroplasty (TKA) remains uncertain, with conflicting evidence regarding associated revision rates and clinical outcomes. Although initial studies have reported higher revision rates associated with unresurfaced patellae, recent evidence questions the necessity of routine patellar resurfacing. This study aimed to evaluate the risk of revision following TKA performed with and without patellar resurfacing using data from the American Joint Replacement Registry (AJRR).The AJRR was queried for all patients aged 65 years and older undergoing elective TKA between January 2012 and March 2020 with a minimum 2-year follow-up. Cases were linked using supplemental Centers for Medicare and Medicaid data. Cases with hybrid fixation, highly constrained implants, and revision components were excluded. Patients were categorized into two groups: those with a resurfaced patella and those without. Cumulative incidence function (CIF) curves and cause-specific Cox models were utilized to assess all-cause revision risk, adjusting for sex, age, femoral design (cruciate retaining vs. posterior stabilized), fixation type (cemented vs. cementless), and Charlson Comorbidity Index.Of the 390,304 TKAs with minimum 2-year follow-up in our cohort, 22,829 had no patellar resurfacing performed. Adjusted hazard ratios (HRs) revealed no significant difference in all-cause revision (HR = 0.96, 95% confidence interval [CI]: 0.81-1.13, p = 0.656), revision for mechanical loosening (HR = 1.61 [0.88, 2.93], p = 0.122), or revision for infection (HR = 1.02 [0.79, 1.33], p = 0.860) associated with patellar resurfacing status.Our study found that patients with an unresurfaced patella do not face an increased short-term revision risk following TKA. These findings challenge the necessity of routine patellar resurfacing and underscore the importance of considering other factors, such as femoral design, patient comorbidities, and implant-related variables in revision risk stratification.

Patellar resurfacing in contemporary total knee arthroplasty: Frequency of complications in a matched cohort

Introduction

Optimum patient selection and outcomes following patellar resurfacing are ongoing debates amongst the arthroplasty community. This study compared the outcomes of patients who had a total knee arthroplasty (TKA) with patellar resurfacing to those left with their native patella.

Methods

A retrospective review of 1941 TKAs performed between 2016 and 2020 was conducted. 41 TKAs without patellar resurfacing and with 2-years of minimum follow-up were identified. Of these, 38 TKAs were matched on age (exact), sex (exact), and body mass index (±10) to 38 TKAs that had patellar resurfacing. The indications for patella resurfacing were subjective based upon the surgeon preference and assessment of cartilage quality. Paired t-tests and chi-square tests were used for analysis.

Results

There was 1 major patellofemoral complication in both the resurfaced group (patellar fracture) and the non-resurfaced group (patellar tendon tear), requiring nonoperative management and revision surgery, respectively. However, in the non-resurfaced group there were 4 cases of subjective patellofemoral pain compared to none in the resurfaced group (p = 0.37). Additionally, 3 non-resurfaced patients required manipulation under anesthesia (MUA) compared to none in the resurfaced group (p = 0.44).

Discussion

There was no difference in the frequency of major patella-specific complications between the groups. However, there was a non-statistically significant trend towards increased patellofemoral pain and MUA in the non-resurfaced group. Based on this study both methods of treatment remain viable options, but the trend towards increased pain and stiffness should continue to be closely evaluated.

Global Trends in Patellar Resurfacing From 2004 to 2022

BACKGROUND

International rates of patellar resurfacing in primary total knee arthroplasty (TKA) are highly variable. This study sought to determine how trends in patellar resurfacing rates have changed between 2004 and 2022. In addition, we investigated how modern rates of revision have varied between resurfaced and unresurfaced patellae in primary TKA among national joint registries.

METHODS

Data between 2004 and 2022 was obtained either from the publicly available joint registry annual reports, a literature review, or via direct correspondence with registry personnel in Sweden, New Zealand, Australia, the United States, Norway, the United Kingdom, the Netherlands, Switzerland, Canada, and India. Only English language national joint registries or data via direct correspondence with registry administrators were utilized. Additionally, the 10-year cumulative risk of revision TKA with and without patellar resurfacing was pulled from those registries that had this data available.

RESULTS

There were persistent differences in the rates of patellar resurfacing among countries. Australia documented a 40% increase in patellar resurfacing rates, while other countries demonstrated modest or little change in resurfacing rates. This may indicate that surgeons are making the decision to resurface based on national TKA revision rates. The average rates of patellar resurfacing in primary TKA ranged from 4% in Sweden to 94% in the United States. Canada, the United States, Australia, and Switzerland documented a lower risk of revision when the patella was resurfaced, while Sweden, conversely, showed a higher risk of revision with resurfacing.

CONCLUSIONS

Rates of patellar resurfacing in primary TKA were highly variable among countries, as were rates of change over time. It appears that the optimal patellar resurfacing strategy may depend mostly on unique patient factors and surgeon expertise. Future studies should attempt to elucidate the individual patient characteristics that contribute to increased risks of revision or anterior knee pain to determine who will most benefit from patellar resurfacing in primary TKA.

Mid-term Outcomes of Patella Resurfacing During Total Knee Arthroplasty (TKA): Clinical, Functional, and Radiographic Insights

Aim The primary objective of the study was to evaluate the mid-term implant survivability, rate of revisions, and clinical and functional outcomes following patella resurfacing during total knee arthroplasty (TKA) utilizing posterior stabilized (PS) total knee system (TKS). Methods A prospective, single-arm, multi-center, post-marketing surveillance encompassed patients with end-stage primary knee osteoarthritis (OA) or inflammatory arthritis. The time points of the study included baseline, six weeks, six months, one year, and three years post-operatively. Clinical outcomes included Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, Short Form-36 questionnaire (SF-36), and Knee Society Score (KSS) for quality of life (QoL). Radiographs assessed loosening, patella tracking, and implant longevity. Functional outcomes were assessed by range of motion (ROM). Result The study included 74 patients undergoing patella resurfacing during TKA with a PS all-poly component TKS at 10 centers in India. Among the study population, 85% were female, and the average age of the population was 65.13±7.20 years. End-stage OA (70 patients) and inflammatory arthritis (four patients) were the prevalent conditions. Patella sizes used were: 25 mm (n=1), 28 mm (n=29), 31 mm (n=40), and 34 mm (n=4). Primary outcomes showed implant survival was 100% with no revisions after three years. Local soft tissue infections and discomfort affected 3.2%, with no additional adverse events. Radiographs showed well-implanted patellar components with no misalignment or wear after three years. Secondary outcomes showed a significant three-year increase in mean ROM from 85.50°±15.02° to 122.45°±2.44°. After three years, clinical and functional KSS improved to 90.36±3.72 (baseline: 21.11±14.49) p<0.001 and 97.95±3.67 (baseline: 27.16±13.22) p<0.001, respectively. WOMAC values for pain, stiffness, and difficulty decreased significantly (p<0.001) over the three-year duration. SF-36 evaluating QoL showed substantial improvements (physical functioning, role limitation, and general health). Conclusion The study highlights the success of patella resurfacing during TKA, demonstrating excellent implant survival, improved functional outcomes, and QoL over a three-year period.

Early Improvement in Postoperative Clinical Outcomes without Patellar Resurfacing in Patella-Friendly Design of Medial Pivot TKA

There is continued debate about the efficacy and indications for patellar resurfacing in total knee arthroplasty (TKA), especially with the emergence of patella-friendly designs. This study aimed to compare the postoperative outcomes in patients undergoing TKA with or without patellar resurfacing using the same implant design. This is a retrospective cohort study of patients who underwent TKA including those with patellar resurfacing (PR group) and those without (NPR group). Demographic data included age, gender, side of surgery, operative time, and body mass index (BMI). Outcomes included preoperative, 2-week, 6-week, and 1-year postoperative Knee Injury and Osteoarthritis Outcome Score and Joint Replacement (KOOS, JR) values along with knee range of motion (ROM). Postoperative complications were recorded. The power analysis with a large effect size indicated that a minimum sample size of 54 was required for Student's t-test and 34 for the paired t-test. A total of 90 medial pivot (MP) TKA were included in this study. There were 30 knees in the PR group and 60 in the NPR group. There was no significant difference between the groups for all demographic data, preoperative and postoperative ROM, and KOOS, JR values at all time points (p > 0.05 for all variables). The KOOS, JR significantly improved in the NPR groups at 2 weeks, 6 weeks, and 1 year postoperatively when compared with the preoperative score and at 6 weeks and 1 year postoperatively in the PR group (p < 0.01). No revisions related to the patellofemoral joint were observed in patients initially undergoing patellar resurfacing. One patient in the NPR group required secondary patellar resurfacing. The patella-friendly MP TKA yielded favorable postoperative outcomes, with or without patellar resurfacing. Improvements in KOOS, JR were observed earlier in the NPR group when compared with the PR group, suggesting that patellar resurfacing may not always be necessary for modern TKA designs. LEVEL OF EVIDENCE:  Retrospective cohort study, Level III.

New evidence on patella resurfacing in modern total knee arthroplasty for all inflammatory arthritis in a mixed Asian population

Background

Traditional teaching advocates for routine patella resurfacing (PR) during total knee arthroplasty (TKA) in patients with inflammatory arthritis. However, evidence on this topic remains limited in the Asian population. This study aims to evaluate the postoperative outcomes and complication of patella resurfacing (PR) during primary total knee arthroplasty (TKA) in Asian patients with inflammatory arthritis.

Methods

A retrospective analysis was conducted using registry data from our institution. Patients with inflammatory arthritis who underwent primary TKA from August 2017 to December 2021 were included in the study. Patients were divided into two groups - patella resurfaced (PR, n = 25) and non-resurfaced patella (PNR, n = 31) groups. Demographics, operative data, patient reported outcome measures, and complications were compared.

Results

Preoperative range of motion (ROM) (PR:95.3 ± 23.6° vs PNR:105 ± 19.5°, p = 0.106), Knee Society Scoring System Knee score (KS-KS) (PR:44.6 ± 17.4 vs PNR:49.3 ± 17.7, p = 0.331) and Knee Society Function Score (KS-FS) (PR:40.9 ± 27.3 vs PNR:47.7 ± 27.0, p = 0.325) and Oxford Knee Score (OKS) (PR:25.0 ± 7.8 vs PNR:23.3 ± 10.3, p = 0.525) were similar in both groups. Outcomes between PR and PNR groups at the one-year mark in terms of ROM (PR:112.7 ± 18.1 vs PNR:114.6 ± 16.5, p = 0.455), OKS (PR:41.5 ± 3.9 vs PNR:41 ± 4.7, p = 0.954), KS-KS (PR:84.5 ± 13.2 vs PNR:89.2 ± 9.3, p = 0.095) and KS-FS (PR:73.6 ± 18.3 vs PNR:78.7 ± 19.3, p = 0.173) were also similar. Intraoperative complication (PR:0/25 vs PNR: 3/31 (9.6 %), p = 0.245) and re-operation rates (PR: 1/25 (4 %) vs PNR: 1/31 (3.2 %), p = 0.877) were also similar in both groups.

Conclusion

This study conducted on a mixed Asian population with inflammatory arthritis demonstrated that the one-year postoperative ROM and functional outcomes, complication, and re-operation rates between PR and PNR groups were similar. Hence, routine patella resurfacing on all Asian patients with inflammatory arthritis undergoing TKA may not be necessary.

Patellar Resurfacing in Total Knee Arthroplasty: A Contentious Matter

Orthopaedic surgeons hold differing opinions on replacing the patella during total knee arthroplasty (TKA) for knee osteoarthritis, sparking a continued discussion on the optimal approach. Patellar resurfacing (PR) replaces the patella's surface with a prosthetic component, aiming to enhance joint function and reduce anterior knee pain. However, it has potential complications such as avascular necrosis, fractures, and patellar clunk syndrome. This analysis evaluates the effectiveness of TKA with and without PR, highlighting the variations in outcomes between the two methods. Findings suggest that resurfacing is associated with improved clinical outcomes, activity level, patient satisfaction, and pain relief. Nevertheless, the decision should be individualized based on patient preferences and circumstances. Additional long-term randomised controlled trials incorporating outcome measures specific to patellar function are required to better understand the effects of PR versus non-resurfacing in TKA.

Minimum 15-Year Survival of a Biconvex Inlay Patellar Component in Primary Total Knee Arthroplasty: An Analysis of 2,530 Total Knee Arthroplasties From a Single Institution

BACKGROUND

Routine patellar resurfacing during primary total knee arthroplasty (TKA) remains controversial. To our knowledge, there are no studies reporting the long-term performance of a cemented biconvex all-polyethylene inlay component implanted at the time of primary TKA. The purpose of this study was to examine the 15-year survivorship and long-term clinical outcomes of this biconvex inlay patella used at our institution.

METHODS

We retrospectively reviewed our prospectively collected institutional database and identified 2,530 patients who underwent cemented TKA with a single prosthetic design (from 1996 to 2007) where the patella was resurfaced using this cemented biconvex inlay patella. The mean age at surgery was 68 years (range, 29 to 93). The mean body mass index was 33.0 (range, 16.4 to 76.3), with 61.9% women. At the time of analysis, the mean time from surgery was 20.4 years (range, 15 to 26). We used Kaplan-Meier analysis to calculate survivorship at 15 years. We analyzed clinical outcomes using 3 patient-reported outcome measures collected prospectively.

RESULTS

The 15-year survivorship with revision surgery for all causes as the end point was 97.1% (95% confidence interval 96.1 to 98.1%). The 15-year survivorship with revision surgery for a patella-related complication as the end point was 99.7% (95% confidence interval 99.4 to 1.0). At the final follow-up, patients showed significant improvement in scores for the Knee Society Clinical Rating System (P < .001), Western Ontario and McMaster University Osteoarthritis Index (P < .001), and Veterans Rand 12-Item Health Survey physical component (P < .001).

CONCLUSIONS

Routine patellar resurfacing using a biconvex inlay patellar component has excellent survivorship and a low rate of complications at 15 years post-TKA.

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.