Subjective evaluation before and after total knee arthroplasty using the 2011 Knee Society Score

Abstract

Background

Patient satisfaction has been recognized as an important evaluation of total knee arthroplasty (TKA). Therefore, the 2011 Knee Society Knee Scoring System (2011 KSS) was developed in order to quantify patient satisfaction, expectations, and physical activities following TKA. However, very few reports have described subjective evaluation before TKA using the 2011 KSS, as the scoring system is still relatively new. Therefore, the degree of improvement and change over time after TKA has not been evaluated.

Methods

Forty-nine consecutive patients (79 knees) with a mean age of 74.8 ± 7.3 years were prospectively included in the study and evaluated preoperatively and one year postoperatively. The following questions were assessed using the 2011 KSS: (1) Do patient-derived clinical scores improve after TKA? (2) Do patient-derived clinical scores before TKA correlate with those after TKA? and (3) Are there correlations among each category of the 2011 KSS score?

Results

The majority of categories showed significant improvements after TKA. The preoperative functional activities score was positively correlated with the postoperative symptoms, functional activities, and objective score. Each category of the 2011 KSS score correlated with others postoperatively.

Conclusions

All patient-derived scores except for patient expectation significantly improved postoperatively. The more functionally active patients before receiving TKA acquired more successful objective and functional outcomes, and the postoperative knee condition was directly influenced by each subscale of the 2011 KSS.

Introduction

Total knee arthroplasty (TKA) is a well-established surgical procedure that generally results in pain relief, improved physical function, and high level of patient satisfaction. Beneficial results are achieved in most patients after TKA, and advanced surgical techniques and prosthesis design have led to improved outcomes [7], [13]. Although the benefits of TKA from the physician's viewpoint, such as range of motion (ROM) and radiographic outcomes, have previously been studied [7], [13], the benefits of the procedure from the patient's point of view are currently unknown. Patient satisfaction has been recognized as an important basis of evaluation in TKA [1], [3], [10], but it is very difficult to quantify and evaluate patient satisfaction and subjective knee function after TKA. In comparison, physician-derived scores can be quantified with ease, but these are poorly related to patient-reported scores [4]. As a result, patient-derived outcome scales have become increasingly important [14].

Previously, the visual analog scale (VAS) and Western Ontario and McMasters Universities Osteoarthritis Index (WOMAC) have been used to evaluate patient satisfaction and subjective knee function [2], despite these instruments not being scoring systems to specifically measure patient satisfaction and knee function after TKA [4]. In 2012, the Knee Society developed a new Knee Society knee scoring system – The 2011 Knee Society Knee Scoring System (2011 KSS) – in order to quantify patient satisfaction, expectations, and physical activities following TKA [16], [19]. However, the literature on the use of the 2011 KSS in evaluating patients' subjective outcomes after TKA is limited due to its novel nature [8], [12], [15], [5]. Furthermore, very few reports have described subjective evaluation before TKA using the 2011 KSS [5], and the degree of improvement and change over time after TKA have not been evaluated.

Therefore, in this study, the following questions were assessed using the 2011 KSS: (1) Do patient-derived clinical scores improve after TKA? (2) Do patient-derived clinical scores before TKA correlate with those after TKA? and (3) Are there correlations among each of the following categories of the 2011 KSS score when administered postoperatively: symptoms, patient satisfaction, patient expectations, and functional activities?