Effect of Different Surgical Approaches on the Early Patellofemoral Joint Function After Total Knee Arthroplasty

Wu Mingyu; Li Xiaofan; Wu Lizhong; Han Guiquan

Abstract：Objective To compare the effects of the subvastus approach and the medial parapatellar approach on the early patellofemoral joint function after total knee arthroplasty.Methods In this retrospective randomized controlled study,80 patients who underwent total knee arthroplasty for knee degenerative diseases at Affiliated Hospital of Weifang Medical University from November 2021 to November 2022 were selected.They were divided into two groups based on the surgical approach:the subvastus approach(SVA)and the medial parapatellar approach(MPA),with 40 cases in each.The SVA group comprised 11 males and 29 females,aged between 55 and 77 years,averaging(66.03± 5.01)years.The MPA group comprised 13 males and 27 females,aged between 56 and 75 years,with an average age of(65.78±4.42)years.Axial knee films at 30 ° and 60 ° flexion in Laurin's position were taken preoperatively and one month postoperatively in both groups to evaluate patellar lateral displacement and tilt angles.Operation time,intraoperative lateral patellar release,postoperative straight leg raising time,range of motion(ROM)at various postoperative stages,visual analogue scale(VAS)for pain,Lonner patellofemoral score,and intraoperative and postoperative complications were compared between groups.Results One month post-surgery,the SVA group exhibited a lateral patellar displacement of(-1.91±1.94)mm at 30 ° knee flexion,outperforming the MPA group(-2.92±2.12)mm(P＜0.05).At 60 ° flexion,the difference in lateral patellar displacement between groups was not statistically significant(P＞0.05).The postoperative patellar tilt angles at 30 ° and 60 ° knee flexion were(5.64± 2.17)° and(5.81±2.13)° in the SV A group,and(6.63±2.12)° and(6.82±1.77)° in the MPA group,both showing significant reductions from preoperative measurements(P＜0.05),with the SVA group exhibiting greater postoperative improvement.The operation time for the SVA group(86.13±6.80)min exceeded that of the MPA group(82.83±6.06)min(P＜0.05).However,the SVA group had better outcomes in terms of intraoperative lateral patellar release,postoperative straight leg raising time,and ROM at different time points:65％,(26.25±6.71)hours,(99.75± 8.87)°,and(106.53±6.67)°,compared to 92.5％,(34.84±7.56)hours,(89.93±11.30)°,and(102.53±8.90)° in the MPA group.Over time,the postoperative Lonner patellofemoral score tended to increase and the VAS tended to decrease in both groups.The SVA group's VAS at different time points postoperatively were superior to the MPA group(P＜0.05).The Lonner patellofemoral scores at one and three months postoperatively were superior to the MPA group(P＜0.05),with no significant difference between the groups at six months postoperatively(P＞0.05).Conclusion Compared with the medial parapatellar approach,the subvastus approach has less impact on patellofemoral function in the early postoperative period after total knee arthroplasty and is more conducive to accelerating postoperative recovery and reducing the occurrence of postoperative patellofemoral joint complications.