Extra-Articular Tibia Vara Affects Radiological Outcome of Total Knee Arthroplasty

He Qiang; Ma Jianbing; Sun Xiangxiang

Abstract：Objective Tibia Vara is an extra-articular deformity,in which the development of medial proximal tibial growth is retarded because of dysplasia.Our objective is to measure tibial varus angle in patients with knee osteoarthritis,to analyze the proportion of patients with tibial varus deformity in patients with knee osteoarthritisand to investigate the effect of tibial varus deformity on the component alignment and clinical outcomes after total knee arthroplasty.Methods We retrospectively reviewed and selected sixty adult patients with varus knee osteoarthritis underwent TKA between from August 2015 to December 2015.The patients were divided into two groups as the tibia vara group and the non-tibia vara group.Two surgeons measured the tibia vara angle (TVA) and Hip knee ankle angle (HKA) in preoperative radiography.All patients were also recorded with the American Knee Society score and WOMAC score preoperatively.After surgery,the HKA and medial proximal tibia angle (MPTA) were measured in long-standing radiography.Patients'' KSS score and WOMAC score were also recorded.Results The mean TVA was (0.69±0.44)° in non-tibia vara group,while the mean TVA was (2.53±0.56)° in tibia vara group.The mean TVA in all patients was (1.12±0.52)°.Nine patients (20%) had TVAs of 0° in in non-tibia vara group.Fourteen patients (100%) had TVAs of more than 2° in tibia vara group.All patients in tibia vara group had TVAs of more than 2 degree.14 out of 60 patients (23.3%) had of more than 2 degree.The mean HKA was (178.8±1.5)°in non-tibia vara group,while the mean HKA was(177±2.0)° in tibia vara group.After TKA,two patients (4.3%) had HKA Outlier in non-tibia vara group,but three ones (21.4%) had HKA Outlier in tibia vara group.The mean range of motion (ROM) was (112.0±11.5)° in non-tibia vara group,while the mean ROM was (105±8.0)° in tibia vara group.The mean WOMAC score was (15.6±3.2) in normal group,while the mean WOMAC score was (16.8±4.0) in tibia vara group.The mean KSS function score was (92.5±3.5) in normal group,while the mean KSS function score was (94.0±2.4) in tibia vara group.Conclusion 23.3% patients of Chinese female people scheduled for TKA had tibia vara (TVA≥2°).The mean TVA in female patients with knee arthritis was (1.12±0.52)°.An TVA greater than 2 degree was found to have a statistically significant influence on postoperative MPTA.Accurate proximal tibial cutting and tibial component lateralized is suggested,if the degree of tibia vara is considable significant.