Prospective comparative study of medial parapatellar and medial subvastus approaches in total knee arthroplasty

Abstract

Introduction Total knee arthroplasty (TKA) is the treatment of end-stage osteoarthritis in patients who failed to respond to conservative treatment in providing significant pain relief and improving joint function. The medial parapatellar approach (MPP) allows adequate patellar eversion and sufficient knee flexion to expose the knee joint, but the incision through the quadriceps tendon may impair the extensor mechanism of the knee post-operatively. The subvastus approach (SV) completely spares both the quadriceps tendon and muscle and provides adequate exposure of the knee joint for the replacement procedure, SV maintains integrity of the patellar blood supply and reduces post-operative pain resulting in shorter hospital stay.The aim of this prospective study was to compare the results of the medial parapatellar and subvastus approaches in primary total knee arthroplasty (TKA) regarding postoperative pain, recovery of muscle strength, range of knee motion and return to regular daily activities.Materials and Methods Sixty patients underwent TKA at El-Hadara university hospital in Alexandria. The medial parapatellar apphroach (MPP) was performed in 30 patients while the subvastus approach (SV) was used for the other 30 patients. The choice of approach was randomly assigned.Results The statistical analysis of the results at the end of a 6-month follow-up showed that there were no significant differences between the patients in group 1 (MPP) and group 2 (SV) with respect to age, gender, comorbidity, side operated or body mass index (BMI). Regarding the functional knee scores (IKDC, WOMAC), there were no differences at 4 weeks, 3 months and 6 months postoperatively between the two groups. However, we found better outcomes in the SV group regarding the VAS score during the first five postoperative days, earlier quadriceps recovery by assessment of Straight Leg Raising test (SLR), while the operative time was longer in the SV group with less blood collected postoperatively in hemovac drain in the same group.Discussion In our study during the operation via the MPP approach, the index suture positioned at the superomedial border of the patella and the opposite suture on the medial retinacular flap had enabled the surgeon to avoid patellar maltracking during closure of the wound. In the SV group, the L-shaped incision of the medial capsule was considered an efficient landmark for accurate soft tissue closure avoiding the patellar maltracking.Conclusion The subvastus approach offers the advantage of keeping the integrity of quadriceps muscle and the extensor mechanism remains intact post-surgery. It causes less pain and less blood loss postoperatively than the regular parapatellar approach. The patient could recover the knee function in a shorter time with fewer complications, which is greatly in line with the concept of ERAS (Enhanced Recovery After Surgery).