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 cm(2) versus 76 cm(2) at 6 weeks, 14 cm(2) versus 29 cm(2) at 6 months, and 7 cm(2) versus 19 cm(2) 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.