There is controversy regarding various aspects of what to do with the patellar component in total knee replacement (TKR). We found in the literature, disparity in the postoperative outcomes and complications associated with the different options. Lateral facetectomy and patellar resurfacing have been demonstrated to be superior to osteofitectomy and denervation of the patella. But there is poor information comparing these two alternatives of treatment.
To compare pain and functional outcomes with Visual Analog Scale (VAS), 2011 2011 Knee Society Knee Scoring System (KSS) and Knee Injury and Osteoarthritis Outcome Score (KOOS) in postoperative primary total knee replacement patients according to the treatment on the patellar component: replacement with patellar button (group 1) or lateral facetectomy (group 2). With preoperative evaluation and 12 months after surgery.
Design and Methods
Ambispective cohort study. We included 89 patients with knee osteoarthritis that were divided into two groups. 43 who underwent TKR with lateral facetectomy and 46 who were performed TKR with patellar resurfacing. In order to complete the sample size, we continued to prospectively include the necessary patients.
Demographic data, pre and postoperative mechanical axis of the lower limb, the prosthetic model used, pre and postoperative 2011 KSS, KOOS, and VAS were evaluated. Also, complications within the first 90 days of surgery were analyzed.
According to Zhang et al a mean postoperative KSS of 88.8 (SD 5+/-) for the facetectomy group and a mean of 83.4 (SD +/-7.6) for the non-facetectomy group were considered, with
level of 0.05 and a power of 80%, at least 24 patients per group would be needed. Considering a loss of 20% and the need to perform an analysis that takes into account confounders, at least 40 patients per group are estimated to be necessary.
Significant differences were found for the patellar resurfacing group in the postoperative categories of overall KSS (p=0,002) and satisfaction KSS (p=0,046) and in the postoperative categories of KOOS symptoms (p=0,002) and quality of life (p=0.004) with better results for these patients. No significant differences in VAS. There were no complications associated with each procedure. Linear regression was performed with age, BMI, pre and postoperative mechanical axis of the lower limb and prosthetic models used, without a relationship with the results described above.
Our study suggests that patients with patellar resurfacing one year after surgery have better outcomes in the variables overall KSS and satisfaction KSS and in the variables symptoms KOOS and quality of life KOOS.