WOUND HEALING PROBLEMS: JUST WHEN YOU THOUGHT IT WAS OVER!

Abstract

Skin necrosis after total knee arthroplasty can rapidly lead to infection of the prosthetic components. Risk factors for the development of skin necrosis include rheumatoid arthritis, steroid use, immunosuppression, malnutrition, peripheral vascular disease, and multiple prior scars.

Vascularity of the skin over the knee will affect the rate of healing postoperatively and risk of necrosis. Johnson measured transcutaneous skin oxygen tension and found that the oxygen tension decreases for the first two to three days after surgery and then increases. In addition, the lateral skin edge is more hypoxic than the medial edge. This suggests that when multiple prior scars are present, the most vertical lateral incision should be used to minimise skin hypoxia.

Constant passive motion further decreases skin oxygen tension. Particularly for patients with multiple risk factors for developing wound complications, avoidance or delayed used of early range of motion exercises may be beneficial in reducing the development of skin necrosis.

If skin necrosis does occur after total knee arthroplasty, early recognition of the problem and treatment will minimise the risk of deep infection of the prosthetic components. Necrosis of the proximal wound including the area over the patella may be treated by local wound care and skin grafting. However, necrosis over the tibial tubercle or patellar tendon requires muscle flap coverage to prevent infection involving the patellar tendon. If the patellar tendon is not viable and the extensor mechanism disrupted, the medial gastrocnemius flap can also be used to augment the extensor mechanism. The tendon of the gastrocnemius is repaired to the quadriceps tendon maintaining continuity between the tibia and extensor mechanism.