[A comparative study of mid- and long-term effectiveness of patellar resurfacing or non-resurfacing in primary total knee arthroplasty].

Objective: To compare the mid- and long-term effectiveness of patellar resurfacing versus non-resurfacing in primary total knee arthroplasty (TKA).

Methods: Twenty-six patients who underwent bilateral TKA between March 2013 and September 2015 were selected as the study subjects. One side was randomly chosen for patellar resurfacing (resurfacing group), and the other side was not (control group). There were 4 males and 22 females, the age ranged from 51 to 65 years, with an average of 59 years. According to Kellgren-Lawrence classification, there were 21 cases of grade Ⅳ and 5 cases of grade Ⅲ in both knees. There was no significant difference in the surgical side, and preoperative clinical and functional scores of the Knee Society Score (KSS), visual analogue scale (VAS) score, and the composition ratio of anterior knee pain localization points between the two groups ( P>0.05). The operation time, intraoperative blood loss, postoperative abnormal signs such as patellar clunk, feeling of constraint, patellar tendon weakness, crepitus, or snow-on-glass sensation, and the occurrence of complications were recorded and compared. Patient subjective evaluations included Forgotten Joint Score (FJS) and the degree of difficulty in high-level knee activities (including flexion with load bearing, going upstairs, going downstairs, squatting and standing up, kneeling, knee extension, and crossing legs for 7 items); KSS clinical/functional scores and VAS scores were used to evaluate the recovery of knee joint function, and the location of anterior knee pain was determined by a localization diagram.

Results: The operation time of the resurfacing group was significantly longer than that of the control group ( P<0.05), and there was no significant difference in intraoperative blood loss between the two groups ( P>0.05). All patients' incisions healed by first intention; the hospital stay ranged from 8 to 23 days, with an average of 12.6 days. All patients were followed up 9-11 years, with an average of 9.7 years. Except for 1 case who died of multiple organ failure due to internal diseases at 9 years after operation and 5 cases with incomplete radiological data, the rest 20 patients were assessed radiologically and found that 1 side of the knee joint in the control group had patellar dislocation; the remaining patients had no prosthetic failure (fracture, loosening, displacement, etc.), patellar fracture, patellar necrosis, patellar instability, patellar tendon rupture, prosthetic revision, etc. No patients had reoperations due to patellar-related complications or anterior knee pain in both knee joints. At 2 years postoperatively and at last follow-up, there was no significant difference in the incidence of abnormal signs such as patellar clunk, feeling of constraint, patellar tendon weakness, crepitus, or snow-on-glass sensation, the incidence of high-level knee activity difficulty, and the composition ratio of anterior knee pain localization between the two groups ( P>0.05). The KSS clinical scores, functional scores, and VAS scores of both groups significantly improved compared to preoperative ones ( P<0.05); there was no significant difference in the comparison between the two groups at the two time points postoperatively ( P>0.05). At 2 years postoperatively and at last follow-up, there was no significant difference in FJS scores between the two groups ( P>0.05).

Conclusion: Patellar resurfacing or not has similar mid- and long-term effectiveness in primary TKA.