The Comparison Between Mini-Subvastus Approach and Medial Parapatellar Approach in TKA: A Prospective Double-Blinded Randomized Controlled Trial

Objective: Minimal invasive approach has been increasingly used in total knee arthroplasty (TKA) and more is expected of early rehabilitation in terms of pain release and recovery of knee function. The approach type is one of the major factors that determines the early rehabilitation after TKA. The purpose of this study is to determine whether mini-subvastus approach (MSVA) is superior to the traditional medial parapatellar approach (MPA) in TKA.

Methods: From 2018 to 2019, a randomized double-blinded prospective study was conducted on 58 patients who underwent simultaneous bilateral TKA. The subjects included eight men and 50 women, with an average age of 65 years. One side was randomized using MSVA and the other side using MPA. Visual analog scale (VAS), operative duration, recovery time to straight leg raising (SLR), range of motion (ROM), HSS score, release rate of lateral retinaculum, satisfaction rate were recorded and compared. Paired-samples T test were used for quantitative data and chi-square test for qualitative data.

Results: There was no statistical difference in the ratio of left and right sides, preoperative ROM, VAS, HSS score, muscular strength of lower limbs, KL grade, operative order, and operative duration between the two groups. The average ROM (118.91 ± 8.21 vs. 107.60 ± 7.99, t = 14.320, p = 0.0000) and HSS score (72.03 ± 4.55 vs. 61.22 ± 4.36, t = 13.095, p = 0.0000) on POD 3, VAS in rest and motion on POD 1 and 3, the recovery time to SLR (1.17 ± 0.38 vs. 3.09 ± 0.76, t = 19.902, p = 0.0000), and the satisfaction rate on POD 1 (96.55% vs. 74.14%, χ  = 9.9251, p = 0.0016) were superior in the MSVA group over MPA group. ROM in rest and motion and HSS score on POD 30 had no difference. The release rate of lateral retinaculum was less in the MSVA group than in the MPA group. The mean value of HKA, FFC, and FTC and the proportion of outliers did not differ significantly between the two groups.

Conclusions: Compared with MPA, MSVA can make ROM of knee and SLR recover earlier, reduce postoperative pain after TKA, improve the early postoperative satisfaction and reduce the lateral release rate. MSVA can be used as a favorable measure in the concept of enhanced recovery after surgery (ERAS).