Outcome of subvastus approach in elderly nonobese patients undergoing bilateral simultaneous total knee arthroplasty: A randomized controlled study

Sir,

We read with great interest the article on the “Outcome of subvastus approach in elderly non obese patients undergoing bilateral simultaneous total knee arthroplasty: A randomized controlled study,”¹ published recently. The authors must be appreciated for doing a randomized controlled study (RCT) on a subject which is not well published in the literature so far.

However, there are few concerns about the usage of subvastus approach for all the primary and revision Total Knee arthroplasty (TKA) cases. We believe that, it cannot be indicated for all the surgeons and for all type of patients. The main limitations includes long learning curve, increased operative time, inadequate exposure due to difficulty in patellar eversion and its relative contraindications in obese people and in revision cases where other approaches have been used before.² In a recent randomized trial³ there was no evidence on primary outcome (American Knee Society Score) to support original hypothesis that the Subvastus approach affords better early outcomes when compared with the Medial Parapatellar (MP) approach. In addition, it was evident from study those surgeons found the SV a more technically difficult surgical approach and that the AKSS Functional scores favored the MP group by 12 months postoperatively.³ Other potential disadvantages of subvastus approach are (a) the reduced overall exposure to the joint with an increased incidence of implant malpositioning, (b) the potential increased risk of damaging the neurovascular structures with subvastus hematoma, (c) the potential vastus medialis damage related to over-stretching and ischemia; and (d) separation or detachment can be seen at the insertion of the patellar tendon.² For these reasons, not surprisingly most surgeons still use a classic medial parapatellar approach.

Vaishya et al., has developed an anterior approach (modified Insall's approach)⁴ for the exposure in all of his primary and revision TKAs for last 15 years.⁵ This novel approach involves cutting and stripping of medial 1/4^th of the quadriceps mechanism from the patella [Figures 1 and 2] and then re suturing it back on the bone, after testing the patellar alignment by doing a 3 stitch test [Figure 3]. This technique gives adequate exposure in all types of knees in both primary and revision situations. In our study of 498 primary TKAs, we observed that the average time taken is far less (56.2 min) than in the present series of cases done by both subvastus (108.5 min) and 94.3 min in medial parapatellar approaches.⁴ This modified approach was not associated with any significant complications, perhaps due to better healing of soft tissues to the patellar bone and excellent exposure.

Figure 1.

Peroperative photographs showing incision site marking of quadriceps mechanism from the medial 1/4^th of the patella

Figure 2.

Peroperative photographs showing cutting and stripping of quadriceps mechanism

Figure 3.

Peroperative photographs showing repair of quadriceps mechanism and testing the patellar tracking by a ‘3 stitch’ test

We therefore agree that subvastus approach may have some theoretical advantages like non violation of quadriceps mechanism, good functional recovery etc., However, it is a tougher technique to master by most surgeons and does not give adequate exposure in difficult cases. Hence, it must be used with caution by occasional TKA surgeons and in challenging cases.