Total knee arthroplasty in Ranawat II valgus deformity with enlarged femoral valgus cut angle: A new technique to achieve balanced gap

Figure 1 Process of total knee arthroplasty. A: Preoperative X-ray of the knee joint in anterior and lateral position; B: The distal femoral valgus osteotomy angle was 7° (red arrow); C: The thickness of the medial femoral condyle osteotomy was more than that of the lateral condyle; D: Tibial plateau osteotomy was taken as the medial tibial plateau reference; E: The osteophyte of the lateral tibial plateau was removed, and the lateral plateau bone defect (black circle) was visible; F: Release of the lateral collateral ligament; G: The thickness of distal femoral osteotomy was increased because the extension space was smaller than the flexion space; H: Postoperative X-ray of the knee joint in anterior and lateral position.

Figure 2 The new osteotomy technique, soft tissue balancing technique, and follow-up results of joint function. A: Schematic diagram of the distal femoral valgus osteotomy. Preoperative lower limb mechanical axis (MA) (a1, blackline), 3° (a2), 5° (a3), and 7° (a4) valgus osteotomy in distal femur osteotomy (white line: new MA; green line: anatomical axis of femur; yellow line: bone cutting plane) are shown, and 5° and 7° valgus cut angle can correct more osseous MA and increase the relative length of the lateral collateral ligament compared with 3° (a5); B: A 65-year-old man with 18° of valgus knee deformity in the new theory total knee arthroplasty (NT-TKA) group. The surgical procedure included osteophytes removal (b1), soft tissue release with a 20 mL syringe needle (b2), osteotomy (b3), straightening gap balance (b4), soft tissue cuff-like release (b5), and buckling gap balance (b6); C and D: Comparison of Oxford knee score (OKS), knee society score (KSS), and range of motion (ROM) between pre- and post-operation in conventional total knee arthroplasty (C-TKA) group (C) and NT-TKA group (D), respectively. ^bP < 0.01, compared with pre-OKS, KSS, and ROM in NT-TKA and pre-KSS clinical stability in C-TKA. ^aP < 0.05, compared with pre-OKS in C-TKA. C-TKA: Conventional total knee arthroplasty; NT-TKA: New theory total knee arthroplasty; OKS: Oxford knee score; KSS: Knee society score; ROM: Range of motion.