2023, Vol. 27 ›› Issue (4): 552-557

Advantage of medial pivot prosthesis in total knee arthroplasty via medial subvastus approach

Wei Bo1, 2, Yao Qingqiang1, 2, Tang Cheng1, 2, Li Xuxiang1, 2, Xu Yan1, 2, Wang Liming1, 2   

Abstract: BACKGROUND: The most commonly used approach for total knee arthroplasty is the medial parapatellar approach, but due to its damage to the quadriceps tendon, it may lead to the weakening of the extensor device in the later stage, thus affecting the long-term functional recovery of patients.  
OBJECTIVE: To evaluate the advantage of total knee arthroplasty with medial pivot prosthesis through medial subvastus approach.  
METHODS: Patients with unilateral knee osteoarthritis who underwent total knee arthroplasty with medial pivot prosthesis from August 2018 to October 2019 were enrolled in this study. Of them, 26 patients received medial subvastus approach and 27 patients received medial parapatellar approach. There were no significant differences in age, sex distribution, body mass index, preoperative hemoglobin, visual analogous scale pain score, knee joint score of Hospital for Special Surgery, and knee range of motion between the two groups (P > 0.05). The operative incision length, operative time, the first postoperative straight leg raising time, the first postoperative activity time out of bed and the postoperative hospitalization time were compared and analyzed between the two groups. Postoperative visual analogous scale pain score, knee Hospital for Special Surgery score, and range of motion of the knee joint were evaluated in both groups.
RESULTS AND CONCLUSION: (1) The mean incision length, the first postoperative straight leg elevation time, the first postoperative movement time, and the postoperative hospitalization time in the medial subvastus approach group were significantly shorter than those in the medial parapellar approach group (P <
0.05). There was no significant difference in the operative time between the two groups (P > 0.05). (2) At 2 days after surgery, the visual analogous scale pain score in the medial subvastus approach group was significantly lower than that in the medial parapatellar approach group (P < 0.001). At 1 month after operation, there was no significant difference in visual analogous scale pain scores between the two groups (P = 0.474). (3) The knee Hospital for Special Surgery score of patients in the medial subvastus approach group was significantly higher than that in the medial parapellar approach group at 1 and 3 months after surgery (P < 0.001). At 1 year after surgery, there was no significant difference in knee Hospital for Special Surgery score between the two groups (P=0.656). (4) At 1 month after surgery, the range of motion of knee joint in the medial subvastus approach group was significantly higher than that in the medial parapatellar approach group (P < 0.001). At 3 months and 1 year after surgery, there was no significant difference in the range of motion of knee joint between the two groups (P=0.298, P=0.999). (5) The use of medial subvastus approach for total knee arthroplasty does not damage the medial vastus tendon, and the extensor device is retained, which is convenient for the installation of medial pivot prosthesis and intraoperative evaluation of medial pivot movement. It can significantly improve the pain and swelling of the limb after operation and effectively promote the early functional exercise.
Key words: total knee arthroplasty, medial pivot knee joint prosthesis, medial subvastus approach, extensor device