Hypesthesia after Anterolateral versus Midline Skin Incision in TKA: A Randomized Study

Background The anterior midline skin incision in a TKA provides excellent surgical exposure. However, it usually requires sectioning the infrapatellar branch of the saphenous nerve which may be associated with lateral cutaneous hypesthesia and neuroma formation.

Questions/purposes We asked whether an anterolateral skin incision to the knee would decrease the area of skin hypesthesia and associated postoperative discomfort.

Patients and Methods We randomized 69 knees to receive a TKA through either a midline or an anterolateral skin incision. We assessed skin sensitivity by application of the Semmes-Weinstein monofilament at 13 reference points at 6 weeks and 6 and 12 months postoperatively. The area of hypesthesia was measured using Mesurim Pro 9^® software. Patient knee ROM, Knee Injury and Osteoarthritis Outcome Score (KOOS), and WOMAC clinical score also were assessed.

Results The area of hypesthesia was less after an anterolateral compared with a midline incision up to 1 year after surgery: the areas of hypesthesia were, respectively, 32 cm²versus 76 cm² at 6 weeks, 14 cm² versus 29 cm² at 6 months, and 7 cm² versus 19 cm² at 1 year. Clinical scores and knee ROM were similar in both groups at each followup. At 1 year, in the entire group we observed a correlation between a smaller area of paresthesia and better WOMAC and KOOS scores and greater knee flexion.

Conclusions Compared with the midline skin incision, the anterolateral incision is associated with fewer sensory disturbances and appears to be a reasonable alternative in TKA.

Level of Evidence Level I, therapeutic study. See the guidelines for authors for a complete description of levels of evidence.