The role of patellar resurfacing in total knee arthroplasty

The ideal treatment of the patella in primary total knee arthroplasty (TKA) for osteoarthritis (OA) remains unclear. Although data exist in the literature to support either resurfacing or not resurfacing the patella, evidence continues to emerge that unresurfaced patellas deteriorate with time. Recent prospective, randomized studies also favor patellar resurfacing over retaining the native patella, reporting reoperation rates to convert unresurfaced to resurfaced patellas exceeding those for complications after patellar resurfacing. In addition, the incidence of residual patellofemoral pain after secondary resurfacing is substantially higher than when patellofemoral resurfacing is done primarily. Patient selection criteria are critical in the decision-making process. Patellofemoral complications, the greatest argument against resurfacing, have been diminished with improved surgical techniques and implant design.     

The role of patellar resurfacing in TKA. Point

While controversy persists, scientific evidence favoring patellar resurfacing in primary TKA is abundant. The literature demonstrates a substantially higher incidence of anterior knee pain and reoperation rates if the patella is not resurfaced primarily. Prospective, randomized studies have reported reoperation rates to convert unresurfaced patellas to resurfaced patellas exceed those for complications after patellar resurfacing. When resurfacing the patella, strict surgical principles are paramount to avoid complications. These include duplicating the original patella thickness, maintaining the patellar blood supply, achieving central patellar tracking, and properly positioning the femoral, tibial, and patellar components. Optimum prosthetic design features for patella resurfacing include an anatomic, asymmetric trochlear groove that is broad, extended, (distally and posteriorly) and deeper compared with first-generation designs.     

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

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

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

BackgroundCurrently, 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.MethodsProspective 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.ResultsLiterature 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.ConclusionPatellar 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.     

Patellar resurfacing in total knee arthroplasty

Routine patella resurfacing in total knee arthroplasty has been debated for decades. The early total knee designs and surgical techniques lead to a high complication rate following patellar resurfacing. This lead to many surgeons abandoning this practice and either leaving the patella unresurfaced routinely or selectively resurfacing. Modern day randomized control trials and meta-analyses of these trials reveal a higher incidience of anterior knee pain and a resultant higher reoperation rate in nonresurfaced patellae. We argue that with modern day designs and surgical techniques, there is a low complication rate to resurfacing and little downside to resurfacing.     

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

Patellar resurfacing in total knee arthroplasty is a topic debated in the literature. Concerns include fracture, dislocation, loosening, and extensor mechanism injury. Residual anterior knee pain has been reported when the patella is not resurfaced. One hundred patients with osteoarthritic knees were prospectively randomized to either have their patella resurfaced or left not resurfaced. All patients were treated with a single prosthesis that featured an anatomically designed patellofemoral articulation (Anatomic Medullary Knee, DePuy, Warsaw, IN) Two patients in the unresurfaced group and one in the resurfaced group required repeat surgery for patellofemoral complications. At 8- to 10-year follow-up evaluations, Knee Society Clinical Ratings scores were not different between the 2 groups. Rates of anterior knee pain with walking and stair climbing were significantly less in the resurfaced group. Eighty percent of patients with a resurfaced patella were extremely satisfied with their total knee arthroplasty versus 48% without patellar resurfacing. When satisfied and extremely satisfied patients were grouped together, there was no difference between the 2 groups.     

Routine patellar resurfacing: a viable option

The literature on routine patellar resurfacing documents that the rate of anterior knee pain after TKA is the same whether the patella is resurfaced or unresurfaced. The complication rate is different in these groups. In patients in whom the native patella is left, the rate of reoperation is approximately 10%. However, when correct surgical technique is used, the rate of patellar complications after routine resurfacing is negligible. Although design modifications have helped reduce patellar complications, the surgeon is the most important variable. As long as good technique is used, routine patellar resurfacing has been proven to produce the best results in TKA.     

Systematic review of patellar resurfacing in total knee arthroplasty

Controversies existing over resurfacing the patella in total knee arthroplasty remain in the literature. The purpose of this review was to evaluate the effectiveness of resurfacing versus nonresurfacing the patella in total knee arthroplasty. We searched the Cochrane Library, MEDLINE and EMBASE for published randomised clinical trials relevant to patellar resurfacing. The relative risk of reoperation was significantly lower for the patellar resurfacing group than for the nonresurfacing group (relative risk 0.57, 95% confidence interval 0.38–0.84, P = 0.004). The overall incidence of postoperative anterior knee pain of the 1,421 knees included was 12.9% in the patellar resurfacing group and 24.1% in the nonresurfacing group. The existing evidence indicates that patellar resurfacing can reduce the risk of reoperation with no improvement in postoperative knee function or patient satisfaction over total knee arthroplasty without patellar resurfacing. Whether it can decrease the incidence of anterior knee pain remains uncertain.     

Secondary patellar resurfacing in total knee arthroplasty: results of multivariate analysis in two case-matched groups

Although patellofemoral symptoms after patellar-retaining knee arthroplasty are common, no evidence has been published in the literature on the potential benefit from patellar resurfacing at a later stage. This study evaluates the effect of secondary (delayed) patellar resurfacing using comparisons between 2 case-matched groups of patients with primary and secondary patellar resurfacing. Furthermore, multivariate statistical methods were applied to study factors that may influence the final outcome. Our results suggest that although significant clinical improvement was seen after delayed patella resurfacing, the outcome of secondary patellar resurfacing is inferior to that expected for a similar group of patients with primary resurfacing. Furthermore, the timing (delay period) of the secondary resurfacing procedure appears to negatively affect the final outcome. This suggests that secondary patellar resurfacing, when indicated, should be considered at an early stage.     

Patellar Resurfacing in Primary Total Knee Arthroplasty: A Meta-Analysis of Randomized Controlled Trials

BackgroundThe management of the patella during total knee arthroplasty (TKA) remains controversial. The aim of this study is to evaluate the evidence regarding the use of patellar resurfacing in TKA.MethodsA meta-analysis of randomized controlled trials (RCTs) was performed to compare outcomes between knees receiving patellar resurfacing vs those not receiving resurfacing during primary TKA. Outcomes of interest were the Knee Society Scores, reoperation rates, anterior knee pain, patient satisfaction, Oxford Knee Score, Knee Injury and Osteoarthritis Outcome Score subscores, and range of motion.ResultsTwenty RCTs met all eligibility criteria and were included in the analysis. There were statistically significant differences favoring the resurfaced group in the knee component and functional component of Knee Society Scores that were not clinically significant. There was an increased risk of reoperation among knees that did not receive resurfacing with number needed to treat to prevent one case of reoperation of 25 knees (for reoperation for any reason) and 33 knees (for reoperation for anterior knee pain). There were no statistically significant differences in any other outcomes.ConclusionThe only clear relationship is that knees that do not receive patellar resurfacing are more likely to receive reoperation, most often for secondary resurfacing. However, the disease burden of differing complication profiles associated with resurfacing and nonresurfacing groups remains unclear. Continuing to collect data from large, well-designed RCTs would be beneficial in guiding management of the patella during TKA.     

全膝关节置换术中髌骨面修整与髌骨置换的比较研究

目的比较全膝关节置换术髌骨面修整和髌骨置换的临床结果。方法2002年1月至12月对60例（60膝）行初次全膝关节置换术的骨性关节炎患者进行前瞻性、随机化研究。所有患者接受相同的后交叉韧带替代型全膝关节假体（PFC）,患者随机行髌骨面修整（髌骨面修整组）或髌骨置换（髌骨置换组）。58例患者平均随访54个月（40～60个月）,对其进行临床评价,包括膝关节协会评分（KSS）、膝关节活动度（ROM）、患者满意度和X线检查。结果两组患者KSS总评分（P=0．12）、KSS疼痛评分（P=0．90）、患者满意度（P=0．22）无明显差异;两组术后膝前痛的发生率均为10％亦无明显差异。两组ROM（P=0．028）和KSS功能评分（P=0．0098）差异有统计学意义。结论全膝关节置换术不论是髌骨面修整还是髌骨置换均能明显减轻疼痛和改善功能。术后膝前痛可能与假体设计和手术技术有关,并非与是否置换髌骨有关。     

Asymmetric patella resurfacing in total knee arthroplasty

Three hundred consecutive primary, cemented, condylar total knee arthroplasties (TKAs) were reviewed for the presence of asymmetric patella resurfacing using a postoperative Merchant or sunrise patellar radiograph. Twenty-one knees in 14 patients were found to have the patella asymmetrically resurfaced. Asymmetric resurfacing typically involved the inadvertent preferential resurfacing of the lateral facet with underresection of bone from the medial patellar facet. All patients underwent follow-up for a minimum of 5 years, with a mean follow-up of 7.5 years. Of the 21 knees, 3 revisions were required for patellar complications. One patellar component was loose on radiographs and there was marked patellofemoral pain in 6 knees. Overall, 11 of 21 knees (52%) underwent revision or were recommended for revision for patellar complications or had anterior knee pain that limited activities. Inadvertent asymmetric patella resurfacing using the kinematic condylar implant adversely affects the outcome after TKA.     

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.     

Anterior knee pain in rheumatoid patients after total knee replacement. Possible selection criteria for patellar resurfacing.

Postoperative anterior knee pain was evaluated in a consecutive series of 138 knees in 108 patients with rheumatoid arthritis treated by total knee replacement with Mark I Insall-Burstein prostheses. No knee had primary patellar resurfacing, and in the 119 knees followed up for a mean of 63.9 months, none had secondary resurfacing. Anterior knee pain was absent in 87 knees (73%), mild in 16 (13.5%) and moderate or severe in 16 (13.5%). The height of the patella above the prosthetic joint line was the only variable which was directly related to the incidence of anterior knee pain. The sensitivity and specificity of patellar height measurements for identifying patients with or without pain were derived. From these data, a selective policy of resurfacing the patella in those at risk was adopted. Choosing a patellar height of 15 mm or less, patellar resurfacing could be avoided in 80% of patients likely to have no pain, and the patella could be resurfaced in 65% of those likely to have anterior knee pain.     

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.     

The consequences of not resurfacing the patella

The decision of whether to resurface the patella during total knee arthroplasty remains controversial. In this study, a meta-analysis of national joint replacement registry data, bilateral total knee replacement studies, selective resurfacing reports, and randomized clinical trials was done Although the evidence seems to support patellar resurfacing, this issue remains inconclusive because of problems generalizing from one implant to another and the short-term nature of available studies. Based on existing data, patellar resurfacing seems reasonable in most total knee replacements. Not resurfacing the patella might be considered in selected younger patients (<60 years) with mild or no patellar arthritis, a well-tracking extensor mechanism, and particularly if a patella-friendly femoral component is used.     

Patellar resurfacing in total knee arthroplasty. A prospective,randomized study

BACKGROUND: Anterior knee pain following total knee arthroplasty is a common complaint and typically is attributed to the patellofemoral joint. The purpose of the present study was to compare the outcome of resurfacing and nonresurfacing of the patella, particularly with regard to anterior knee pain, and to clarify the indications for patellar resurfacing at the time of total knee arthroplasty. METHODS: We performed a prospective, randomized study of 514 consecutive primary press-fit condylar total knee replacements. The patients were randomized to either resurfacing or retention of the patella. They were also randomized to either a cruciate-substituting or a cruciate-retaining prosthesis as part of a separate trial. The mean duration of follow-up was 5.3 years (range, two to 8.5 years), and the patients were assessed with use of the Knee Society rating, a clinical anterior knee pain score, and the British Orthopaedic Association patient-satisfaction score. The assessment was performed without the examiner knowing whether the patella had been resurfaced. At the time of follow-up, there were 474 knees. Thirty-five patients who had a bilateral knee replacement underwent resurfacing on one side only. RESULTS: The overall prevalence of anterior knee pain was 25.1% (fifty-eight of 231 knees) in the nonresurfacing group, compared with 5.3% (thirteen of 243 knees) in the resurfacing group (p < 0.0001). There was one case of component loosening. Ten of eleven patients who underwent secondary resurfacing had complete relief of anterior knee pain. The overall postoperative knee scores were lower in the nonresurfacing group, and the difference was significant among patients with osteoarthritis (p < 0.01). There was no significant difference between the resurfacing and nonresurfacing groups with regard to the postoperative function score. Patients who had a bilateral knee replacement were more likely to prefer the resurfaced side. CONCLUSIONS: As the present study showed a significantly higher rate of anterior knee pain following arthroplasty without patellar resurfacing, we recommend patellar resurfacing at the time of total knee replacement when technically possible.     

Patellar resurfacing in total knee arthroplasty: a prospective, randomized trial

BACKGROUND: The management of the patella in total knee arthroplasty is still problematic. We aimed to identify differences in the clinical outcome of total knee arthroplasty according to whether or not patellar resurfacing had been performed in a prospective, randomized study of 220 osteoarthritic knees. METHODS: Two hundred and twenty total knee arthroplasties in 201 patients were randomly assigned to be performed with either resurfacing or retention of the patella, and the results were followed for a mean of forty-eight months (range, thirty-six to seventy-nine months) in a double-blind (both patient and clinical evaluator blinded), prospective study. Evaluation was performed annually by an independent observer and consisted of assessment with the Knee Society clinical rating system, specific evaluation of anterior knee pain, a stair-climbing test, and radiographic examination. RESULTS: Fifteen (12%) of the 128 knees without patellar resurfacing and nine (10%) of the ninety-two knees with patellar resurfacing underwent a revision or another type of reoperation related to the patellofemoral articulation. This difference was not significant (chi square with one degree of freedom = 0.206, p = 0.650). At the time of the latest follow-up, there was a significantly higher incidence of anterior pain (chi square with one degree of freedom = 5.757, p = 0.016) in the knees that had not had patellar resurfacing. CONCLUSIONS: Patients who underwent patellar resurfacing had superior clinical results in terms of anterior knee pain and stair descent. However, anterior knee pain still occurred in patients with patellar resurfacing, and nine (10%) of the ninety-two patients in that group underwent a revision or another type of reoperation involving the patellofemoral joint. Weight but not body mass index was associated with the development of anterior knee pain in the patients without patellar resurfacing, a finding that suggests that patellofemoral dysfunction may be a function of joint loading rather than obesity.     

Patellar resurfacing complications in total knee arthroplasty

Purpose

The ideal management of the patella during total knee arthroplasty (TKA) is still controversial. Patellar retention is generally associated with an increased rate of anterior knee pain; however, patient satisfaction is similar in cases of replacement or retention. When the patella is replaced, potential severe complications can occur. Aim of this study was to retrospectively review results of a continuous series of patients having been treated with TKA and patella resurfacing.

Methods

The charts of 1,600 consecutive total knee prostheses were analysed to evaluate the rate of patellar resurfacing. All implants were posterior stabilized; 310 patients having received a patellar replacement were reviewed at follow-up (FU) examination. Complete physical examination as well as administration of the Hospital for Special Surgery (HSS) score was performed. X-rays analysis included weightbearing anteroposterior (AP) and lateral views of the injured knee and bilateral skyline views at 30° flexion.

Results

Two hundred and eighty patients were available for clinical and imaging investigation at an average FU of 96 (58–144) months. Mean age at the time of surgery was 70 (62–80) years. Mean HSS score was 85.9 ± 7.6. The overall rate of patellofemoral complications was 7 % (19 cases); 13 patients claimed anterior knee pain, five had symptomatic patellar maltracking and one had patellar component loosening.

Conclusion

Our data are in accordance with those available in the literature. Recent meta-analyses demonstrated lower risk of re-operation after patellar resurfacing. However, when complications of the resurfaced patella occur, they can be potentially catastrophic events.     

Total knee arthroplasty without patellar resurfacing

One hundred and eleven total knee replacements without patellar resurfacing were followed-up for a minimum of 48.8 months (range 48.8-108.2 months; average 78.2 months). Evaluation was performed using the Knee Society Clinical Rating System (KS-CRS). Preoperatively, the mean knee score was 34.3 points and the mean function score was 42.2 points. Postoperatively, this knee score improved to a mean of 91.1 points and the function score improved to mean of 89.6 points at the most recent follow-up. There were no significant differences among the knees with mild, moderate, or severe degenerative change to the patella with regard to the preoperative (p=0.83) and postoperative (p=0.39) knee pain score. It seems likely that the postoperative knee pain is not related to the severity of degenerative change to the patella in total knee arthroplasties performed without patellar resurfacing, and none of those patients required patellar resurfacing to achieve knee pain relief.