2024, Vol. 28 ›› Issue (24): 3827-3832

Effect of varus and valgus angles of tibial prosthesis on short-term outcome of fixed bearing unicompartmental knee arthroplasty

Wang Hu, Feng Shuo, Zhang Qiang, Chen Jiahao, Chen Xiangyang   

Abstract: BACKGROUND: Previous studies on the effects of valgus and varus angles of tibial component on short-term postoperative outcomes after mobile bearing unicompartmental knee arthroplasty have been reported in and outside China. However, there are few reports on the effect of the valgus and varus angles of tibial component on short-term postoperative outcomes after fixed bearing unicompartmental knee arthroplasty.
OBJECTIVE: To investigate the effect of valgus and varus angles of tibial component on short-term clinical outcomes in patients with medial knee osteoarthritis undergoing fixed bearing unicompartmental knee arthroplasty.  
METHODS: 120 patients (122 knees) who underwent fixed bearing unicompartmental knee arthroplasty for medial knee osteoarthritis in Department of Orthopedic Surgery, Affiliated Hospital of Xuzhou Medical University from August 2020 to January 2023 were selected as the study subjects. Two physicians measured the varus angle of femoral prosthesis, valgus and varus angles of tibial prosthesis, flexion and extension angles of femoral prosthesis, and posterior inclination angle of tibial prosthesis after unicompartmental knee arthroplasty based on postoperative X-ray. After excluding the influence of the other three angles, the measurement results of the tibial component varus angle were divided into three groups: <-2°,-2° to 2°, >2°, which were denoted as groups 1, 2, and 3, respectively. The range of knee motion, the hospital for special surgery knee score, the American knee society score, and forgotten joint score were recorded and compared before and after the operation.   
RESULTS AND CONCLUSION: (1) A total of 120 patients (122 knees) were enrolled in this study. They were divided into three groups according to the size of the valgus and varus angles of the tibial prosthesis after operation: 37 patients in the first group, 60 patients in the second group, and 23 patients in the third group. There was no significant difference between the three groups in terms of baseline information such as age, gender, and side of surgery (P > 0.05). (2) Patients were followed up for 3-30 months after arthroplasty. (3) The hospital for special surgery knee score of the second group was higher than that of the first group (P=0.015) and the third group (P=0.012). The American knee society score of the second group was significantly higher than that of the first group (P=0.014) and the third group (P < 0.001). The forgotten joint score of the second group was higher than that of the first group (P=0.033) and the third group (P=0.016). (4) After fixed bearing unicompartmental knee arthroplasty, when the valgus angle of tibial prosthesis was   -2° to 2°, which can achieve better short-term clinical results, the degree of prosthesis self-realization is higher.

Key words: unicompartmental knee arthroplasty, medial knee osteoarthritis, varus and valgus angles of tibial prosthesis, fixed bearing, clinical effect