Lateral approach is advantageous in total knee arthroplasty for valgus deformed knee
For the total knee arthroplasty in valgus deformed knee, superiority of the medial or lateral approach is still controversial. We compared the short-term result of two approach groups. Forty-seven knees in rheumatoid arthritis with valgus deformity from 6° to 24° were randomly divided into two group; medial approach (24 knees) and lateral approach (24 knees). We used Scorpio NRG PS for all knees. Median postoperative periods were 43 months in both groups. We compared the surgical time, and alignment on standing radiograph, range of motion (ROM) pre/postoperatively, and degrees of soft-tissue release procedure, and lateral laxity measured by stress radiograph immediately after operation and at final follow-up. Pre/postoperative alignment, surgical time, lateral laxity, and preoperative ROM had no significant in two groups; however, postoperative flexion was superior in lateral approach group 123.8°, 109° in medial approach group. All cases required iliotibial band (ITB) release at Gerdy’s tubercle, 83 % ITB at joint level, 21 % lateral collateral ligament (LCL), 17 % popliteus tendon (PT) in medial approach group, and 88 % ITB at Gerdy’s tubercle, 46 % ITB at joint level, 13 % LCL, 4 % PT in lateral approach group. In the valgus knee, lateral structures are tight. Lateral approach can directly adjust the tight structure, and also less vascular compromise to the patella than medial approach with lateral patellar release. Less invasiveness to the quadriceps muscle in lateral approach could result into better range of motion after the surgery.