Influence to early postoperative quadriceps strength of minimally invasive and conventional approaches in total knee arthroplasty: a prospective randomized controlled

Abstract

Objective To compare the quadriceps strength and short-term outcome in patients who had undergone primary total knee arthroplasty (TKA) with minimally invasive (MIS) or conventional surgical technique.Methods Sixty-eight knees undergoing TKA were evaluated and they were randomly divided into two groups.One group included 34 knees which were undergone conventional approach,and the other group included 34 knees undergone MIS approach.The age,BMI,quadriceps strength,extension lag,American Knee Society Score (KSS),Western Ontario and McMaster Universities (WOMAC) osteoarthritis index and visual analogue scale (VAS) of pain of all patients were evaluated at the day before surgery and the 1st,2nd,3rd,6th,and 12th months after surgery.Results At the 1st,2nd,3rd,6th,and 12th months after surgery,the quadriceps strength in MIS group was 0.59±0.12,0.74±0.18,0.86±0.16,1.02±0.17,1.05±0.04 N·m/kg respectively,while in conventional group was 0.46± 0.56,0.56±0.12,0.70±0.16,0.94±0.19,1.04±0.03 N· m/kg respectively.The extension lag in MIS group was 13.11°±6.56°,8.53°± 5.12°,4.79°±3.62°,1.53°±2.64°,1.62°±1.76° respectively,while in conventional group was 22.47°±8.41°,16.23°±6.26°,10.58°± 4.4°,2.58°±2.85°,1.62°±1.76° respectively.There were significantly differences in the two groups.Meanwhile,compared with conventional patients,MIS patients demonstrated significantly higher KSS scores at the 1st and 2nd months postoperatively.WOMAC scores were significantly lower in MIS group than in conventional group at the 1st month after surgery.During the first postoperative week,MIS technique significantly decreased VAS scores,showing significance.On the other hand,no significant difference was observed with respect to deep infection incidence and radiological outcome between two groups.Conclusion MIS TKA offers a significant improvement in extensor muscle strength over conventional surgery.These results suggest that the MIS approach results in better outcomes with regard to maintaining extensor strength than the conventional surgical approach. Key words: Surgical procedures, minimally invasive; Arthroplasty, replacement, knee; Quadriceps muscle; Muscle strength