Comparison of scars and resulting hypoaesthesia between the medial parapatellar and midline skin incisions in total knee arthroplasty

The two most common skin incisions in total knee arthroplasty (TKA) are the medial parapatellar and midline. As the medial parapatellar incision is predominantly parallel to the Langer's lines of the knee, this may give a better cosmetic appearance. The aim of this study was to assess patient satisfaction of the surgical scar and resulting hypoaesthesia following TKA. Two groups of patients who underwent primary TKA were reviewed. Group 1 consisted of 91 patients who underwent primary TKA using a medial parapatellar incision and trivector arthrotomy with a mean follow up of 2.8 years. Group 2 consisted of 76 patients who underwent primary TKA using a midline incision and medial parapatellar arthrotomy with a mean follow up of 2.7 years. The scars were assessed using the validated Manchester Scar Proforma (MSP) and Visual Analogue Scales (VAS). The resulting hypoaesthesia was assessed using VAS. The mean MSP for Group 1 and Group 2 was 11.7 and 11.9 respectively. The mean area of hypoaesthesia for Group 1 and Group 2 was 28.9 cm2 and 23.8 cm2 respectively. There was no statistical significance in any of the parameters measured. The mean length of the incision scar was 19.5 cm for Group 1 and 19.4 cm for Group 2. Both produced equal and excellent cosmetic results. Patients in both groups had hypoaesthesia around the knee at 7 years following their TKA. Hypoaesthesia was not found to be of significant concern to patients. This information may be useful when consenting patients for TKA.