[A comparative study on effectiveness of patellar resurfacing against non-resurfacing in total knee arthroplasty]

To investigate the effectiveness of total knee arthroplasty (TKA) with or without patellar resurfacing.

Between March 2013 and August 2015, 30 patients (60 knees) with osteoarthritis who met the inclusion criteria were recruited in the study. Of 30 cases, 24 were male and 6 were female with an average age of 57.2 years (range, 37-65 years). The body mass index ranged from 19.5 to 40.3 kg/m ² (mean, 28.2 kg/m ²). According to Kellgren-Lawrence grading, there were 8 cases at grand Ⅲ and 22 cases at grand Ⅳ. All patients underwent primary bilateral TKA. The patellar resurfacing was done at the unilateral knee randomly (resurfacing side); the opposite treatment was done at the other side (non-resurfacing side). The indexes of 2 groups were recorded and compared, including the intraoperative blood loss, operation time, knee society score (KSS), "Forgotten Joint" scale (FJS), anterior knee pain, anterior patellar spirant, knee constraint feeling, anterior patellar clunk, muscle power of knee extension, and ability of up and down stairs, weight-bearing flexion, squatting down, cross-legged, knee down, knee extension, and patient satisfaction. Radiographic examination was used to analyze the prosthesis position.

The operation time were (126±14) minutes and (112±11) minutes in resurfacing side and non-resurfacing side, respectively, showing significant difference between two sides ( t=5.103, P=0.030); and there was no significant difference in intraoperative blood loss between two sides ( t=3.431, P=0.800). All patients were followed up 2-4 years (mean, 2.6 years). There was no significant difference ( P>0.05) between two sides in KSS clinical and functional scores at preoperation and 6 weeks, 6 months, and 2 years after operation; in visual analogue scale (VAS) score of anterior knee pain at preoperation and 6 weeks after operation; in incidences of anterior patellar spirant, knee constraint feeling, anterior patellar clunk, and muscle power of knee extension at 6 weeks, 6 months, and 2 years after operation; in incidences of disability of up and down stairs, weight-bearing flexion, squatting down, cross-legged, knee down, and knee extension at 6 weeks, 6 months, and 2 years after operation; in ratio of FJS score at 2 years after operation. The VAS scores at 6 months and 2 years after operation in resurfacing group were significantly lower than those in non-resurfacing group ( Z=-1.997, P=0.046; Z=-2.197, P=0.028). Patient satisfaction of resurfacing side was superior to the non-resurfacing side at 6 weeks after operation ( χ²=4.271, P=0.039). Radiographic examination showed no prosthesis loosing occurred.

The effectiveness of TKA with patellar resurfacing is better than that with non-resurfacing in patients satisfaction.