Abstract: Abstract: Objective To study the influence of outward-transferring the location of femoral medullary opening in Xray imaging and short-term clinical outcomes during total knee arthroplasty (TKA) with lateral femoral arch deformity. Methods Forty patients (60 knees) with knee arthropathy and with femoral lateral arch angle more than 3 degrees treated in Tianjin hospital from March 2014 to June 2017 were selected in this study. All patients were performed total knee arthroplasty. The cases were divided into two groups according to whether the position of femoral medullary opening was adjusted or not. Twenty-eight knees were in the standard position of femoral medullary opening group, referred to as the control group, and 32 knees were in the outward-transferring position group. The opening position was 5 mm horizontal outward shift than the standard position, referred to as the test group. In both groups, intramedullary osteotomy was performed. The fixation of 6 degrees was used as the angle of valgus osteotomy of distal femur. Statistical data of the two groups were collected to evaluate the operation situation and compare the difference of imaging and clinical effect between the two groups at 1 year after operation. The imaging evaluation included femoral lateral arch angle, preoperative hip-kneeankle angle, femoral valgus angle, postoperative hip-knee-ankle angle, femoral prosthesis angle, tibial prosthesis angle and patellofemoral congruent angle. Clinical efficacy evaluation included Western Ontario and McMaster Universities Osteoarthritis Index, Knee Society Score Clinical Score and Feller Patella Score before surgery and 1 year after operation. Then, 180°±3°, 90°±2°, 90°±2° and ≤10° were used as the criteria to evaluate the quality in the mechanical axis, femoral prosthesis position, tibial prosthesis position and patellofemoral joint. Results The baseline data of the two groups were consistent. All the operations were performed with Posterior Cruciate-Retaining (CR) knee prosthesis. No injury or rupture of medial or lateral collateral ligaments occurred. All operation time was less than 70 minutes, and the apparent bleeding volume was 10-20 mL. All incisions healed well after operation. At the last follow-up, no complications such as infection, prosthesis loosening and periprosthetic fracture were found in both groups. There were no significant differences in the duration of operation, femoral arch angle, preoperative hip-knee-ankle angle, femoral valgus angle, postoperative tibial prosthesis angle, postoperative tibial prosthesis excellent and good rate, patellofemoral joint excellent rate, preoperative WOMAC index, KSS clinical score, Feller patella score and 1 years postoperative WOMAC index between the two groups (P＜0.05). However, the hip-knee-ankle angle, femoral prosthesis angle and patellofemoral angle were better in the test group than those in the control group (P＜0.05). The excellence rate of mechanical axis and femoral prosthesis position in the external displacement group was better than that in the control group (P＜0.05). KSS clinical score and Feller patella score were higher in the test group than those in control group at 1 year after surgey (P＜0.05). Conclusion For TKA patients with moderate to severe lateral arch deformity of femur, reasonable displacement of femoral opening position can improve lower limb alignment, prosthesis position and patellofemoral joint relationship. The short-term follow-up has good clinical effect.

Key words: osteoarthritis, knee, arthroplasty, replacement, knee, femur deformity, limb alignment, mechanical axis