64 – HYPOESTHESIA AFTER TOTAL KNEE ARTHROPLASTY: A RANDOMISED, CONTROLLED TRIAL COMPARING LATERAL PARAPATELLAR TO MINI MEDIAL INCISION IN TOTAL KNEE ARTHROPLASTY

Abstract

Purpose: Antero-medial parapatellar skin incision in total knee arthroplasty (TKA) provides excellent surgical exposure with minimal skin incision length. However, it is associated with the infrapatellar branch of the saphenous nerve section, leading to antero-lateral knee hypoesthesia and sometimes painful nevroma. We hypothesized that

• antero-lateral skin incision in TKA produces a lower rate of hypoesthesia compared to the medial parapatellar cutaneous approach, and

• reduced hypoesthesia is linked with less discomfort and possibly a better clinical outcome.

Method: A total of 69 knees in 64 patients who underwent TKA were randomized for antero-medial (n=35) or antero-lateral (n=34) skin incision. Mean age was 66.4±8.2 years. Functional outcome was assessed by WOMAC, KOOS and SF-36 scores pre-operatively and at six weeks, six months and one year follow-up. Range of motion (active and passive flexion and extension) was measured. The area of hypoesthesia was analyzed in a standardized manner by an independent observer using a calibrated Semme-Weinstein monofilament applied on 13 reference points. A digital photograph was taken, and the area of hypoesthesia was then measured informatically (Mesurim Pro^® software). Patient satisfaction with their scar and their surgery was evaluated. Statistical analysis was carried out with p< 0.05 considered as significant.

Results: The two groups were comparable pre-operatively. There was no significant difference in functional outcome (WOMAC, KOOS, SF-36 scores) at six weeks, six months and one year between the two groups. Active and passive ranges of motion were comparable. The area of hypoesthesia and the number of non-perceived points in the monofilament test were significantly lower after antero-lateral incision at six weeks (p=0.007 and p=0.02, respectively) and 6 months (p=0.02 and p=0.005, respectively). At one year, the area of hypoesthesia was lower in the antero-lateral group, but was not significant (p=0.08). Antero-lateral incision patients reported a lower rate of subjective sensitivity loss and anterior knee pain at six weeks, six months and one year.

Conclusion: Antero-medial and antero-lateral parapatellar skin incisions in TKA have a similar functional outcome. However, antero-lateral cutaneous incision produces a lower rate of hypoaesthesia and less anterior knee pain in the early recovery period.