Author's reply

We are grateful to Vaishya et al.¹ for showing interest in our article.² We agree with the comment that, the Subvastus approach cannot be generalized to all knee arthroplasty patients and they need to be individualized. We select our patients on the basis of inclusion criteria detailed in the paper.² In our practice, we use medial para-patellar approach in all our revision cases. The main motto, behind this approach is to make the patients out of bed as early as possible.

There are some disadvantages to this approach, which are pertaining to its limited exposure, but this has never been an issue in our set of patients. An article by Teng et al.,³ revealed significant differences which favored the subvastus approach. Knee Society Score was better in subvastus group at 4-6 weeks; lateral retinacular release was not required in subvastus group, when compared with the medial para-patellar approach. However, both groups showed similar results in range of motion, operative time, blood loss, hospital stay and postoperative complications.³ It's also evident from our study that, patients with subvastus approach do well in the earlier days post-surgery, although, its quiet evident from the literature that the outcomes are similar at long term followup.²

According to an article by Hu et al., patients with subvastus approach needed less lateral release and offered earlier straight leg raise and superior knee flexion within 1 week postoperatively with no increase in the duration of surgery.⁴

According to a study by Matsueda et al., The patella tracked centrally in significantly more knees with the Subvastus approach (83% of their knees) than with the para-patellar approach (63%).⁵ An electrophysiological study, showed increase in turn-amplitude analysis in the group of subvastus approach, as an indicator of a faster functional improvement of knee extensor mechanism in these cases.⁶ The medial subvastus approach allows good surgical exposure, faster straight leg raising, full weight bearing without aid and shorter length of stay with most importantly no radiological malalignment.⁷

In a systemic review comparing minimally invasive surgery with medial para-patellar approach, authors concluded that, compared to the standard medial para-patellar approach, the minimally invasive group had a longer operative duration, decreased blood loss, significantly lower Visual Analogue (VAS) score at days 3-5 post operation; better Mean Knee Society scores at week 6 postoperative.⁸

We do agree that subvastus approach is difficult to master, has a long learning curve, cases needs to be individualized and in difficult revision cases it's better to proceed with an extendable medial para-patellar approach.