Variables Determining the Postoperative Knee Range of Motion Following Cruciate-substituting Total Knee Replacement: A Prospective Study

Introduction Range of motion (ROM) is a major desirable outcome after total knee arthroplasty (TKA). The aim of our study is to analyze the variables determining postoperative knee ROM, following cruciate-substituting TKA of arthritic knees. Methods One-hundred fourteen patients out of a total of 158 patients were studied on the basis of the inclusion criteria. All patients underwent cruciate-substituting TKA in the period between September 2014 and September 2017. Variables such as age, sex, body mass index (BMI), preoperative ROM, mild-to-moderate knee deformity (in both the sagittal and coronal planes) and knee society score (KSS) were recorded for all the patients. The patients were evaluated at intervals and finally at the end of one-year post-surgery. The final ROM and KSS were noted. Data were analyzed in SPSS system using the Kruskal-Wallis test and Mann-Whitney U test. Results Patients with younger age (less than 60 years), more preoperative ROM, and less preoperative fixed flexion deformity (FFD) were found to have better postoperative ROM. The mean preoperative KSS was 42.14 ± 12.02, which improved to 90.86 ± 3.86 postoperatively. Other variables like gender, BMI, and preoperative coronal plane deformity of mild to moderate degree did not have a significant influence on postoperative ROM. Conclusion Postoperative expectations of ROM is an important factor for a successful outcome and is also related to patient satisfaction. Variables like younger age group (less than 60 years), better preoperative ROM and lower preoperative FFD are found to have a better postoperative ROM in patients undergoing cruciate-substituting TKA surgery.