Patella resurfacing versus nonresurfacing in total knee arthroplasty: results of a randomized controlled clinical trial at a minimum of 10 years' followup

Patellar resurfacing in total knee arthroplasty remains controversial. This study evaluates the results of resurfacing and nonresurfacing the patella in a randomized controlled, clinical trial at a minimum of 10 years followup. One hundred knees (90 patients) with osteoarthritis were enrolled in a prospective randomized clinical trial using a posterior-cruciate-retaining total knee arthroplasty. Patients were randomized to receive resurfacing or retention of the patella. Evaluations were done preoperatively and yearly, up to a minimum of 10 years (range, 10.1-11.5 years) postoperatively. Disease-specific (Knee Society clinical rating score) and functional (stair climbing, flexion/extension torques, patellar examination) outcomes were measured. Patient satisfaction, anterior knee pain, and patellofemoral questionnaires were completed. Intraoperative grading of the articular cartilage was done. No patients were lost to followup; 45 patients remained alive. Nine revisions (in nine of 90 knees; 10%) were done in seven patients in the nonresurfaced group (15% of knees) and in two patients in the resurfaced group (5% of knees). No significant difference was found between the groups regarding revision rates, Knee Society clinical rating scores, and functional, patient satisfaction, anterior knee pain, patellofemoral, and radiographic outcomes. Intraoperative cartilage quality was not a predictor of outcome. This study currently is the longest followup of a randomized controlled, clinical trial that examines patellar resurfacing in total knee arthroplasty. The results showed no significant difference between the groups for all outcome measures at a minimum of 10 years of followup.     

A meta-analysis of patellar replacement in total knee arthroplasty

From individual randomized studies it is unclear whether the patella should be replaced during total knee replacement. We did a meta-analysis to provide quantitative data to compare patellar resurfacing with nonresurfacing during total knee arthroplasty. Only randomized, controlled trials reported between January 1966 and August 2003 comparing patellar replacement with patella retention were included for a total of 12 studies. Two reviewers assessed trial quality and extracted data from papers. The outcomes identified were reoperations for patellar problems, anterior knee pain, knee scores, stair climbing, and patient satisfaction. The resurfaced patella performed better, and we found an increased relative risk (defined by the ratio of the risk of the event in the resurfaced group on the risk of the event in the nonresurfaced group) for reoperation, for significant anterior knee pain, and for significant pain during stair climbing when the patella was left unresurfaced. No differences were observed between the two groups for International Knee Society function score, Hospital for Special Surgery score, and for patient satisfaction. Despite these general findings, forming a definitive conclusion is difficult because many confounding factors, such as component design, surgeon experience, and technical aspects of the surgery, might influence the result in a patient.     

Selective patellar nonresurfacing in total knee arthroplasty. 10 year results.

Patella nonresurfacing in total knee arthroplasty was reviewed retrospectively in 49 knees (42 patients). Thirteen patients (17 knees) died leaving 29 patients (32 knees) in the final study group. The minimum length of followup was 10 years and averaged 11.7 years (range, 10-13.4 years). The diagnosis was primary osteoarthritis in 26 knees, posttraumatic arthritis in four, osteonecrosis in one, and Paget's disease in one. Patients were evaluated using the Knee Society score, a patella score, and radiographs. The mean Knee Society score improved from 52.8 to 87.5 points postoperatively and functional score improved from 57.5 to 84.5 points postoperatively. Anterior knee pain was reported in six knees (20%). Only one patient required secondary resurfacing of the patella because of postoperative anterior knee pain. No significant correlation was found between anterior knee pain and patellofemoral joint space, patellar sclerosis, Insall-Salvati ratio, patellar tilt, gender, obesity, or age. Based on the need for secondary patellar resurfacing because of anterior knee pain, the 10-year survival was 97.5%. At minimum 10-year followup, retaining the patella in total knee arthroplasty in selected patients with osteoarthritis of the osteoarthritic knee can yield acceptable results.     

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.     

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。     

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.     

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.     

Patellar resurfacing in total knee arthroplasty. A prospective, randomized, double-blind study with five to seven years of follow-up

BACKGROUND: Whether to resurface the patella during a primary total knee arthroplasty performed for the treatment of degenerative osteoarthritis remains a controversial issue. Parameters that have been suggested as being useful in guiding this decision include patient height and weight, the presence of anterior knee pain preoperatively, and the grade of chondromalacia encountered intraoperatively. The purpose of this study was to determine whether these parameters were predictive of the clinical result following total knee arthroplasty with or without patellar resurfacing. METHODS: Eighty-six patients (118 knees) undergoing primary total knee arthroplasty for the treatment of osteoarthritis were enrolled in a prospective, randomized, double-blind study. All patients received the same posterior-cruciate-sparing total knee prosthetic components. Patients were randomized to treatment with or without resurfacing of the patella. Evaluations consisted of the determination of a Knee Society clinical score, the completion of a patient satisfaction questionnaire, specific questions relating to patellofemoral symptoms, and radiographs. Sixty-seven patients (ninety-three knees) were followed for a minimum of five years (range, sixty to eighty-four months; average, 70.5 months). RESULTS: With the numbers available, there was no significant difference between the groups treated with and without resurfacing with regard to the overall Knee Society score or the pain and function subscores. Obesity, the degree of patellar chondromalacia, and the presence of preoperative anterior knee pain did not predict postoperative clinical scores or the presence of postoperative anterior knee pain. CONCLUSIONS: The occurrence of anterior knee pain could not be predicted with any clinical or radiographic parameter studied. On the basis of these results, it seems likely that postoperative anterior knee pain is related either to the component design or to the details of the surgical technique, such as component rotation, rather than to whether or not the patella is resurfaced.     

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.     

髌骨置换与否对全膝关节置换术后疗效的影响

目的 探讨膝骨关节炎患者行全膝关节表面置换时髌骨置换与否对术后疗效及并发症发生的影响.方法 对2007年1月至2011年12月之间行人工全膝关节置换术的170例(237膝)骨关节炎患者,按髌骨置换(126膝)和未置换(111膝)分为2组.对术前和末次随访时两组的HSS评分、膝前痛评分、膝关节活动度、最大屈曲度数、屈曲畸形及手术时情况和患者满意度等进行对比分析.结果使用SPSS 17.0统计软件包进行统计学分析.结果 在170例(237膝)OA患者中161例(21 3膝)获得随访,平均随访时间(40.94±8.02)个月,置换组HSS评分由术前的(40.19±8.14)分增加到末次随访时的(87.45±6.00)分(P＜0.05),膝前痛评分由(4.13±1.08)分升高到(19.47±4.04)分(P＜0.05);未置换组HSS评分由(40.00±6.74)分上升到(88.93±4.92)分(P＜0.05),膝前痛评分由(3.58±2.26)分变化到(13.61±3.89)分(P＜0.05);患者满意度置换组为80.91％,未置换组为61.17％(P＜0.05).在HSS评分、膝关节活动度、最大屈曲度数、屈曲畸形等方面两组差异无统计学意义.而在膝前痛评分、患者满意度、手术时间、术中失血量等方面差异有统计学意义.结论 当膝关节骨关节炎患者进行全膝关节置换术时,若术前存在膝关节疼痛严重、患者期望较高、不适合长时间手术,应行髌骨置换.     

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.     

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.     

Patella resurfacing in patients without substantial retropatellar knee pain symptoms?

OBJECTIVE: The aim is of this prospective randomised study was to investigate the necessity of resurfacing the patella in combination with total knee arthroplasty in patients without or mild anterior knee pain before undergoing total knee replacement. METHODS: Between May 1999 and May 2000 fifty patients were enrolled in a prospective, randomised study. All patients received the same posterior-cruciate-sparing total knee replacement and were randomised to treatment with and without resurfacing of the patella. Inclusion criteria were primary osteoarthritis of the knee, preoperatively no pain when the patella was shifted during clinical examination, a maximal grade III radiological degeneration of the patella according to Sperner et al. and at most a mild anterior knee pain in preoperative interview. Evaluations consisted of the determination of the Knee Society clinical score, the completion of a patient satisfaction questionnaire, and radiographic assessment basing on the Knee Society roentgenographic evaluation and scoring system. All patients were examined preoperatively and 3, 6, and 12 months postoperatively. RESULTS: In all postoperative examinations patients with patella resurfacing demonstrated a higher overall Knee Society score. At month 6 the difference was statistically significant. The patient satisfaction questionnaire demonstrated no significant difference between both groups. However, regarding to relief of anterior knee pain and improvement of pain in general patients with nonresurfacing were less satisfied at all follow-ups. Furthermore, after 12 months all answers to the patient satisfaction questionnaire of the resurfaced group were better. Patella-associated revisions were performed in two patients without resurfacing. Radiographic analysis demonstrated no loosening, fracture, subluxation or dislocation. CONCLUSION: The presented study demonstrated after one year follow-up a better functional result, a higher degree of contentment and fewer complications after total knee replacement with patella resurfacing in patients without or mild preoperative anterior knee pain.     

膝关节置换术中髌骨置换与非髌骨置换比较的Meta分析

[目的]系统评价全膝关节置换术中髌骨置换与否对术后疗效的影响,为临床治疗提供参考。[方法]全面搜索国内外关于膝关节置换术中髌骨置换和非髌骨置换的随机对照研究资料,按照既定的纳入、排除标准,核定检出符合评价标准的文献,提取所需研究数据,采用RevMan 4.2软件进行Meta分析。[结果]纳入随机对照研究16篇,共计1 922例膝关节置换术。Meta分析结果显示,髌骨置换组术后5年内发生膝前痛的风险降低,加权后RR=0.53,95%CI(0.30,0.94),但5年后二者无明显统计学差异。髌骨置换组术后5年以上发生再手术的风险低,加权后RR=0.35,95%CI(0.18,0.66),但5年内二者无明显统计学差异。膝关节KSS评分不论是亚组分析还是总体分析,均无统计学差异。总体分析结果,KSS评分加权均数差值为0.44,95%CI(-1.22,2.09)。[结论]全膝关节置换术中髌骨置换与非髌骨置换相比,术后5年内膝前痛发生率低,术后5年以上再手术的风险低,关节评分无明显差别。髌骨置换与非髌骨置换的优劣仍需大规模多中心的RCT来进一步研究。     

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.     

全膝关节置换术中髌骨置换与髌骨成形对膝关节功能的影响

 目的 探讨髌骨置换与髌骨成形对全膝关节置换术后膝关节功能的影响。方法 对2010年8月至11月拟行全膝关节置换术的48例(69膝)膝关节骨关节炎患者进行随机分组,髌骨置换组24例(35膝)、髌骨成形组24例(34膝)。两组患者年龄、体重、身高、体重指数、美国膝关节协会(Knee Society Score,KSS)膝评分及功能评分、髌骨评分的差异均无统计学意义。比较两组术后6周、3个月、6个月、12个月、24个月的KSS膝评分及功能评分、髌骨评分、术后膝前痛发生率及影像学表现。结果 髌骨置换组20例(30膝)与髌骨成形组20例(29膝)获得随访。术后各时点两组KSS膝评分的差异无统计学意义;6个月以后髌骨置换组KSS功能评分高于髌骨成形组,12个月以后髌骨置换组髌骨评分高于髌骨成形组,差异有统计学意义。术后各时点髌骨置换组膝前痛发生率与髌骨成形组的差异有统计学意义。术后24个月髌骨置换组与髌骨成形组术后胫股角(174.25°±0.97°与173.63°±0.48°)、髌韧带比值(1.01±0.09与1.09±0.07)、髌骨倾斜角(4.58°±0.18°与4.41°±0.19°)、髌骨适合角(2.69°±4.15°与2.56°±3.72°)、髌骨移位距离[(1.53±1.34) mm与(1.68±1.23) mm]的差异均无统计学意义。结论 全膝关节置换术中行髌骨置换可以改善膝关节和髌骨功能,降低术后膝前痛的发生率。     

全膝关节置换术中髌骨置换与否对早期疗效及膝前痛的影响

 目的 探讨全膝关节置换术中髌骨置换与否对早期疗效及膝前痛发生率的影响。方法 2010年6月至2011年6月拟行全膝关节置换术患者100例,随机分为两组：髌骨置换组43例50膝,髌骨未置换组57例66膝。比较术后6个月、12个月两组患者的西安大略和麦克马斯特大学(West Ontario and McMaster Universities,WOMAC)骨关节炎指数、美国膝关节外科协会(Knee Surgery Society,KSS)膝评分和功能评分、膝前痛视觉模拟评分(visual analogue scale,VAS)。结果 髌骨置换组与髌骨未置换组患者术后膝前痛VAS评分均较术前明显降低,两组间VAS评分及膝前痛发生率的差异无统计学意义。WOMAC骨关节炎指数6个月分别为28.8±11.2和18.6±7.2、术后12个月分别为20.7±6.2和16.0±5.5,KSS膝评分6个月分别为(87.0±8.3)分和(90.9±7.2)分、术后12个月分别为(84.2±10.6)分和(88.8±9.2)分,KSS功能评分术后6个月分别为(86.6±21.6)分和(84.9±16.5)分、术后12个月分别为(85.2±16.4)分和(91.0±10.0)分,组间差异均无统计学意义。髌骨轴位X线片示髌骨与股骨假体滑车吻合度良好,无不稳及脱位表现。术后1年内无翻修、髌骨表面再置换病例。结论 全膝关节置换术对改善因骨关节炎或类风湿关节炎导致的膝关节疼痛、功能受限有效;髌骨置换与否对术后短期疗效及膝前痛发生率没有影响。     

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

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

全膝置换术后的髌腱短缩及其临床影响

目的研究全膝置换(totalkneearthroplasty,TKA)术后的髌腱长度变化,置换髌骨对髌腱长度的影响,髌腱长度变化与术后膝关节活动度的关系。方法2002年5月~2003年12月对49例55个关节行初次全膝置换手术。包括48例骨关节炎、7例类风湿性关节炎,其中7例做了外侧支持带松解,测量术前的髌腱长度及术后1年的髌腱长度和膝关节活动度,按是否置换髌骨分成两组,对数据进行组间和组内统计学分析。结果术后1年,髌腱发生有统计学意义的短缩(P<0·01)。在短缩大于10%的发生率上,换与不换髌骨组没有统计学意义的差别(P>0·05)。髌腱短缩和关节活动度呈负相关(P<0·01)。结论全膝置换术后存在髌腱短缩的并发症。置换髌骨对髌腱短缩没有影响。髌腱短缩可能是导致术后活动度损失的原因之一。     

Effect of femoral component design on unresurfaced patellas in knee arthroplasty

Three total knee designs were evaluated to test the hypothesis that femoral component design affects the clinical and mechanical functions of the unresurfaced patella after total knee arthroplasty. Patients with the Ortholoc II, Advantim, and Profix femoral components were followed up for as many as 14 years and revision rate, anterior knee pain, and generalized knee pain were compared. A laboratory protocol was devised to evaluate pressure in the patellofemoral joint of knees from cadavers with a pressure-sensitive transducer using the same three designs at various degrees of knee flexion. Thirty Ortholoc II knee components were followed up for 14 years. Nineteen patients (63%) had severe anterior knee pain and 15 patients (50%) had reoperation to resurface the patella within 2 years. Two hundred one patients (222 knees) with Advantim components were followed up for 10 years and 305 patients (330 knees) with Profix components were followed up for 5 years. No patients with these two knee designs had severe anterior knee pain or reoperation for patellar resurfacing. A significantly higher rate of mild anterior knee pain was seen in the patients with Advantim components than in the patients with Profix components. No apparent relationship was seen between the severity of patellar wear found at the time of surgery and the incidence of anterior knee pain. Patients with rheumatoid arthritis receiving either the Advantim or Profix knee component performed as well as patients with osteoarthritis when the patella was not resurfaced. Pressure was significantly higher in the patellofemoral joints of the laboratory knee specimens with Ortholoc II components than in the specimens with either the Advantim or Profix components. The specimens with Advantim components had significantly higher pressure than did the specimens with normal knees, and the specimens with Profix components differed little from those with normal knees.