Contact stresses with an unresurfaced patella in total knee arthroplasty: the effect of femoral component design

Compressive contact stresses between the patella and the anterior femur were measured with a digital electronic sensor before and after total knee arthroplasty (TKA) in 10 cadaver knee specimens. Contact stresses were measured first in normal knees, then after TKA with the Insall-Burstein Total Condylar, Miller Galante II, Ortholoc II, Porous Coated Anatomic, and Profix knee prostheses implanted without resurfacing the patella. The Insall-Burstein, Miller-Galante II, and Ortholoc II prostheses had significantly higher contact stresses than the normal knee throughout the flexion arc. The Porous Coated Anatomic, which has a smooth patellar groove, maintained contact area as in the normal knee and did not have significantly higher contact stresses at flexion angles <90 degrees. At flexion angles > or =105 degrees, patellofemoral contact occurred in two small areas as the patella encountered the intercondylar notch in all components except the Profix. The Profix maintained full contact and low compressive stresses throughout the full flexion arc because of its posteriorly extended patellar groove. Design features of the patellofemoral portion of TKA components are important factors that affect contact stresses in the patellofemoral joint. These features likely will affect the clinical results of TKA with an unresurfaced patella.     

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.     

Patellofemoral complications with the Insall-Burstein II posterior-stabilized total knee arthroplasty

The Insall-Burstein and Insall-Burstein II posterior-stabilized (I-B II PS) prostheses have been reported to have a high prevalence of patellar complications. This is a prospective, consecutive study of 118 primary total knee arthroplasties in 82 patients with the I-B II PS prosthesis implanted by 1 surgeon, using a specific technique for patellar resurfacing. The mean follow-up time was 4.0 years (range, 2-8 years). Clinical evaluation was performed using a standard knee score system with specific additional evaluation of the patellofemoral joint. Radiographs were evaluated for fracture, loosening, and subluxation. Ninety-four knees (80%) were rated excellent, 21 knees (17%) good, and 3 knees (3%) fair. The mean flexion was 112 degrees postoperative. No knee required reoperation for the patellofemoral joint. There were 2 nondisplaced and 1 minimally displaced patellar fractures treated nonoperatively, no patellar clunk syndrome, and no subluxations. Using the patellar evaluation system, 109 knees had no anterior knee pain, 7 knees had mild pain, and 2 knees (1 patient) had moderate-to-severe pain only with rising from a chair. Patellofemoral crepitus with active flexion-extension in the seated position was noted in 16 knees (14%) but was painful in only 2 knees (1 patient). With this technique for patellar resurfacing with this prosthesis, patellofemoral complications were only 4.2%, and no knee required reoperation for the patella or for loosening. With attention to operative technique, patellofemoral resurfacing with this posterior-stabilized total knee arthroplasty can be highly successful.     

Clinical results of Whiteside Ortholoc total knee replacement

Three hundred and four consecutive cementless Ortholoc I TKAs were followed for 2 to 5 years. One patient had femoral and tibial component loosening. There were no cases of patellar component loosening, but six knees had failure of the patellar polyethylene surface due to wear. A major design change of the metal-polyethylene locking mechanism was effected to address this problem. The patellar component is now countersunk and the central post has been reduced in size. 79.1 per cent of the knees were graded excellent, 13.4 per cent good, 5.8 per cent fair, and 1.7 per cent poor. The Ortholoc I group was compared to a similar group of 424 Ortholoc II knees at 1 year postoperatively for pain relief. The Ortholoc II knee differs from the Ortholoc I primarily in tibial component fixation, using four peripheral 6.5-mm screws. The Ortholoc II group had significantly fewer painful knees, which suggests that the screws in the tibial component were effective in improving fixation and controlling load distribution. Survival analysis showed no tendency for the results to deteriorate over the time span studied. Cementless fixation of all components, including the tibia and patella, was highly successful and can be achieved without stress relief of the distal femur.     

One-peg versus three-peg patella component fixation in total knee arthroplasty.

In many designs of total knee arthroplasty, the patella with one central peg has been replaced by a patella with three small pegs for cement fixation. There have been recent reports of failure of this design. This is a prospective, consecutive study of two types of patella component fixation in 228 posterior-stabilized knee arthroplasties done by one surgeon. A central peg all-polyethylene component was used for 84 consecutive knees in 63 patients (Group A) and a three-peg patella was used for the next 144 consecutive knees in 99 patients (Group B). The mean followup was 6.7 years (range, 2-10 years) for Group A and 3.5 years (range, 2-6 years) for Group B. Except for the patellar component fixation, all knees had the same posterior-stabilized prosthesis using a specific protocol for patellar resurfacing. No patient required reoperation for a patellofemoral complication. The prevalence of patella fracture was higher in Group A, 4.7% (four knees), compared with 2.1% (three knees) in Group B, but this difference was not statistically significant. The presence of anterior knee pain referable to the patella was 7.1% (five patients, six knees) in Group A (one patient with two knees had severe anterior knee pain) and 9% (13 knees in 13 patients) in Group B. There was no patella clunk syndrome, subluxation, or fracture of a fixation peg in either group. With this specific protocol for patella resurfacing, there was a higher rate of complications with the one central peg patella (4.7%) than with the three-peg patella (2.1%), but this did not reach statistical significance. The results do not support an increased risk of component failure with this three-peg patella design, but do not, at this length of followup, show any significant advantage of three-peg fixation.     

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.     

Arthroscopic treatment of patellar clunk.

Excellent results have been reported with posterior stabilized total knee arthroplasty. A common complication relating to patellofemoral articulation is patellar clunk syndrome. Patellar clunk syndrome occurs when a fibrous nodule develops just proximal to the patellar button. At approximately 30 degrees to 45 degrees from full extension, the nodule catches the anterior flange of the femoral prosthesis, resulting in the clunk and a painful range of motion. The present study examines the use of arthroscopic debridement for this disorder. Thirty consecutive patients (32 knees) with the diagnosis of patellar clunk syndrome were evaluated at 1 year after arthroscopic debridement. All patients were evaluated clinically and radiographically according to the Knee Society score. In addition, patients were questioned specifically regarding anterior knee pain and patellofemoral symptoms. Radiographs were evaluated further regarding patella and component position. Patients were diagnosed with patellar clunk at an average of 12 months after their latest knee arthroplasty, with a range of 3 to 47 months. All patients complained of anterior knee pain and the clunk. All patients had a hypertrophic nodule at the junction of the proximal pole of the patella and quadriceps tendon and underwent arthroscopic debridement through a superolateral portal. All patients were free of patellar clunk postoperatively; one patient reported persistent anterior knee pain. Knee Society scores increased from an average of 64 points preoperative to 93 points postoperative. Radiographs showed patella alta in eight knees, patella baja in two. Four femoral components were in 5 degrees flexion. The present study represents the largest collection of data regarding patellar clunk syndrome. The data appear to support arthroscopic debridement as a successful treatment of patellar clunk syndrome.     

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.     

Total knee replacement with and without patellar resurfacing: a prospective, randomised trial using the profix total knee system.

We have examined the differences in clinical outcome of total knee replacement (TKR) with and without patellar resurfacing in a prospective, randomised study of 181 osteoarthritic knees in 142 patients using the Profix total knee system which has a femoral component with features considered to be anatomical and a domed patellar implant. The procedures were carried out between February 1998 and November 2002. A total of 159 TKRs in 142 patients were available for review at a mean of four years (3 to 7). The patients and the clinical evaluator were blinded in this prospective study. Evaluation was undertaken annually by an independent observer using the knee pain scale and the Knee Society clinical rating system. Specific evaluation of anterior knee pain, stair-climbing and rising from a seated to a standing position was also undertaken. No benefit was shown of TKR with patellar resurfacing over that without resurfacing with respect to any of the measured outcomes. In 22 of 73 knees (30.1%) with and 18 of 86 knees (20.9%) without patellar resurfacing there was some degree of anterior knee pain (p = 0.183). No revisions related to the patellofemoral joint were performed in either group. Only one TKR in each group underwent a re-operation related to the patellofemoral joint. A significant association between knee flexion contracture and anterior knee pain was observed in those knees with patellar resurfacing (p = 0.006).     

The Richards type II patellofemoral arthroplasty: 26 cases followed for 1-20 years

We followed 26 Richards type II patellofemoral arthroplasties in 24 patients (19 women) for a mean of 11 (1-20) years. Their mean age was 59 (22-90) years. The preoperative diagnoses were primary patellofemoral arthrosis in 17 cases and secondary arthrosis in 9 (8 malalignment, 1 patellar fracture). Patellectomy was later performed for persistent pain or patellar malalignment in 3 cases and a conversion to a total knee arthroplasty for progressive tibio-femoral degeneration or patella malalignment in 2. The mean Knee Society knee score for 21 knees at follow-up was 90 (65-100) points. The patients rated the results of surgery in 9 knees as excellent, 7 good, 4 improved, and 1 unimproved at follow-up. None of the implants showed signs of loosening or infection. The Richards type II patellofemoral arthroplasty yields acceptable long-term results in patients with isolated end-stage patellofemoral osteoarthrosis. Patient selection and patella alignment are important.     

The Richards type II patellofemoral arthroplasty: 26 cases followed for 1-20 years

We followed 26 Richards type II patellofemoral arthroplasties in 24 patients (19 women) for a mean of 11 (1-20) years. Their mean age was 59 (22-90) years. The preoperative diagnoses were primary patellofemoral arthrosis in 17 cases and secondary arthrosis in 9 (8 malalignment, 1 patellar fracture). Patellectomy was later performed for persistent pain or patellar malalignment in 3 cases and a conversion to a total knee arthroplasty for progressive tibio-femoral degeneration or patella malalignment in 2. The mean Knee Society knee score for 21 knees at follow-up was 90 (65-100) points. The patients rated the results of surgery in 9 knees as excellent, 7 good, 4 improved, and 1 unimproved at follow-up. None of the implants showed signs of loosening or infection. The Richards type II patellofemoral arthroplasty yields acceptable long-term results in patients with isolated end-stage patellofemoral osteoarthrosis. Patient selection and patella alignment are important.     

The Richards type II patellofemoral arthroplasty: 26 cases followed for 1-20 years.

We followed 26 Richards type II patellofemoral arthroplasties in 24 patients (19 women) for a mean of 11 (1-20) years. Their mean age was 59 (22-90) years. The preoperative diagnoses were primary patellofemoral arthrosis in 17 cases and secondary arthrosis in 9 (8 malalignment, 1 patellar fracture). Patellectomy was later performed for persistent pain or patellar malalignment in 3 cases and a conversion to a total knee arthroplasty for progressive tibio-femoral degeneration or patella malalignment in 2. The mean Knee Society knee score for 21 knees at follow-up was 90 (65-100) points. The patients rated the results of surgery in 9 knees as excellent, 7 good, 4 improved, and 1 unimproved at follow-up. None of the implants showed signs of loosening or infection. The Richards type II patellofemoral arthroplasty yields acceptable long-term results in patients with isolated end-stage patellofemoral osteoarthrosis. Patient selection and patella alignment are important.     

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.     

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。     

Patellar resurfacing reduces pain after TKA for juvenile rheumatoid arthritis

Influence of patellar resurfacing after knee replacement and the frequency of patella infera and its relation to the postoperative appearance of the knee pain were assessed in patients with juvenile rheumatoid arthritis. Seventy-seven total knee arthroplasties using the AGC prosthesis with nonconstrained components were done on 52 patients with a mean followup of 7.3 years (range, 3-13 years). Anterior knee pain was present in 14 of 30 patients (47%) with an unreplaced patella and in two of 18 patients (11%) with patella resurfacing. The patella was replaced in 18 patients (35%) and in 23 of 77 knees (30%). Neither revision surgery of implanted patellar components nor any later resurfacing of an unreplaced patella were done during the followup. Preoperatively using the Insall-Salvati ratio, the majority of knees (54 of 77) had a low-riding patella. Patella infera occurred commonly in patients with juvenile rheumatoid arthritis. No connection between patella infera and anterior knee pain was found.     

Optimizing patellofemoral tracking during total knee arthroplasty

Fifty-seven patients who underwent 65 primary TKAs between 1993-1994 were retrospectively studied to identify the technical challenges and pitfalls associated with patellar resurfacing and to improve patellar tracking during total knee arthroplasty (TKA). Average patient age was 69 years. All surgeries were performed by a single surgeon (J.N.I), and the same prosthesis was used in all patients. Intraoperatively, attention was paid to avoid femoral and tibial component malrotation and prevent overstuffing of the patellofemoral joint. Preoperative limb alignment was varus in 42 knees, neutral in 6 knees, and valgus in 17 knees. Average pre-resection patellar thickness measured 23.8 mm and post-resection thickness averaged 21.5 mm. No patella-prosthesis composite was thicker than the native patella. Two (3%) knees required a formal lateral release to improve patellar tracking at surgery. Average follow-up for 53 patients (61 knees) was 5 years. At latest follow-up, 4 (6%) patients reported mild anterior knee pain, 5 (7%) patients reported pain with stairs, and 2 (3%) patients had knee crepitus without pain. No dislocations or recurrent subluxations occurred. No patient required revision surgery for patellofemoral complication. Awareness of the anatomic variability, attention to component rotation, and restoration of the normal patellar height improves patellar tracking and minimizes patellofemoral instability following TKA.     

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.     

髌骨半脱位70例治疗分析

目的探讨髌骨半脱位的治疗方法及其预后。方法回顾性分析70例（130膝）髌骨半脱位患者的临床资料,其中男30例,女40例;年龄10～48岁,平均23岁。患者髌骨的形态均为WibergⅡ、Ⅲ型,其中伴有外侧髌股关节骨关节炎者58例108膝,高位髌骨23例46膝,外伤后股四头肌内侧头肌张力不良10例10膝。Q角20°～40°。全部行手术治疗,手术方式包括：髌外侧支持带充分松解（130膝）;髌内侧支持带紧缩、股内侧肌移位至髌骨前内侧（12膝）;髌骨外侧部分切除（17膝）;胫骨结节前、内侧移位（46膝）,平均内移1．0cm、前移1．2cm;缝匠肌前移（11膝）,半腱肌前移（13膝）;关节镜下髌外侧支持带松解,髌内侧支持带紧缩（31膝）。术中见全部病例髌外侧支持带均明显增厚。结果随访3～180个月,根据Insall等评分系统评估分析疗效,术后疗效优78膝,良33膝,可12膝,差7膝。患者术后疼痛、关节活动功能均得到明显改善,尤其是解除膝前痛效果显著。结论根据病因及病理改变选择恰当的手术方式治疗髌骨半脱位均可取得满意的效果,特别是关节镜手术具有创伤小、恢复快的特点,值得进一步推广应用。     

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.     

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.