Tibial anteroposterior axis measured by CT scan in optimizing tibial prosthesis rotation during total knee arthroplasty

Zhang Lei; Lian Kai; Peng Hao; Chen Sen

doi:10.3969/j.issn.2095-4344.0042

Abstract：BACKGROUND: The osteotomy and prosthesis placement of the traditional total knee arthroplasty is mostly done by visual measurement and lacks more precise measurements. OBJECTIVE: To identify rotational alignment of tibial prosthesis using preoperative calculation of tibial anteroposterior axis by CT scan and to compare the clinical efficacy of tibial prosthesis placement in traditional total knee arthroplasty. METHODS: Data of 50 patients with knee osteoarthritis who underwent primary total knee arthroplasty in Department of Orthopedics, Renmin Hospital of Wuhan University from January 2014 to April 2015 were retrospectively analyzed. All patients were randomly divided into two groups: 23 cases (25 knees) received preoperative CT to measure the tibial anteroposterior axis in CT assistant group; 27 cases (29 knees) received the method of medial 1/3 of the tibial tubercle in traditional surgery group. We recorded operative time and hospital time, pre- and post-operative Hospital for Special Surgery score, patellar score, knee range of motion and Visual Analogue Scale score. At 3 days after surgery, X-ray images were obtained to measure tibial valgus β and tibial slope valgus θ. All operations were performed by the same team. RESULTS AND CONCLUSION: (1) All patients were followed up. There was no significant difference between two groups in the general information (P > 0.05). (2) Operative time, tibial valgus β and tibial slope valgus θ assessed in CT assistant group were better than in traditional surgery group (P < 0.05); there was no significant difference in hospital time between the two groups (P > 0.05). (3) There was no significant difference in Hospital for Special Surgery score, patellar score, range of motion, and Visual Analogue Scale score between the two groups pre-operatively, 1 and 3 months after operation (P > 0.05). However, above indexes were better in the CT assistant group than in the traditional surgery group at 6 months after operation (P < 0.05). (4) Results indicated that the tibial anteroposterior axis measured by CT for guiding tibial prosthesis position was more precise than the traditional surgery to make the femur prosthesis and the tibial prosthesis have better rotating alignment.