Summary

This clinical study found no significant differences between total knee arthroplasty and unicompartmental knee arthroplasty in both of patient-derived and physician-derived outcomes, except for postoperative functional activities using 2011 Knee Society Score at the short-term postoperative period.

Abstract

Background

Total knee arthroplasty (TKA) and unicompartmental knee arthroplasty (UKA) have been recognized as good surgical treatments of progressive osteoarthritis. Although the comparison of clinical outcomes between TKA and UKA have been previously reported based on implant survivorship, radiological parameters, and physician-derived outcome measures, few reports have described the comparison of patient-derived outcomes. The 2011 Knee Society Score (2011 KSS) was developed in order to quantify patient-derived outcomes including patient satisfaction, expectations, and physical activities following knee arthroplasty. To our knowledge, no series of patient-derived outcomes of both of TKA and UKA have been reported using the 2011 KSS as the scoring system is still relatively new. Therefore, in this study, the comparison of patient-derived outcomes between TKA and UKA were evaluated using the 2011 KSS.

Methods

From May 2012 to July 2015, 70 patients with 74 primary TKAs and 30 patients with 32 UKAs were prospectively enrolled in this study. Patients with bone defects needing bone grafting or augmentation, revision arthroplasties, rheumatoid arthritis, and those who underwent an alternative surgical procedure during the study were excluded. Seventy-two knees had a diagnosis of osteoarthritis and 2 knees had a diagnosis of osteonecrosis in TKA groups, and 17 knees had a diagnosis of osteoarthritis and 15 knees had a diagnosis of osteonecrosis in UKA groups. The mean age of TKA and UKA groups were 74.8 ± 7.3 years and 71.3 ± 8.0 years, respectively. The patients answered all components of the 2011 KSS questionnaire that consists of symptoms, patient satisfaction, patient expectations, functional activities, and objective knee indicators as physician-derived outcome measures preoperatively and 1 year postoperatively. The 2011 KSS scores after TKA were compared with those after UKA. Furthermore, the improvement rates of the 2011 KSS score to divide postoperative score by preoperative score during TKA and UKA were compared.

Results

The postoperative functional activities score was significantly higher in the UKA groups than in the TKA groups. The other categories of the 2011 KSS including objective knee indicators showed no significant differences between TKA and UKA groups. There were no significant differences in the improvement rates of all categories of the 2011 KSS during TKA and UKA.

Conclusions

The findings of this analysis is that although patients who undergo UKA acquire more functional activities than the patients who undergo TKA, the improvement of functional activity during UKA is similar to those during TKA. This clinical study found no significant differences between TKA and UKA in both of patient-derived and physician-derived outcomes, except for postoperative functional activities at the short-term postoperative period.