Lateral arm flap: analysis of its anatomy and modification using a vascularized fragment of the distal humerus

Soft tissue injuries with associated bone defects are difficult to manage and often require prolonged treatment with repeated interventions. Frequently, a free flap is applied as a first step and bone grafting is carried out in a second procedure. Ideally, these two procedures are combined in one operation, utilizing a soft tissue flap with an attached vascularized bone fragment. The lateral arm flap can provide such an osteoseptocutaneous flap and has been utilized clinically with success; however, the vascular anatomy of the flap, especially the humeral fragment, has not been described in detail previously, and there is broad disagreement concerning its innervation. In this study, the arteries and nerves of 24 fresh cadaver arms were dissected after injection of colored latex. The levels of origin of the periosteal arteries of the humerus were also documented. The lateral arm flap has a consistent arterial supply from three septocutaneous perforating branches that are arranged in a predictable pattern. The lateral supracondylar ridge of the humerus is vascularized by direct branches of the posterior branch of the radial collateral artery and by arteries that arise from muscular branches supplying adjacent muscles. The innervation of the lateral arm flap is by the inferior lateral cutaneous nerve of the arm. Knowledge of the consistent vascular anatomy of the lateral humerus and soft tissue of the donor site allows an osteoseptocutaneous flap to be raised safely with an appropriate technique. We recommend use of the lateral arm flap with a humeral fragment for the treatment of combined soft tissue and bone defects when a single step surgical solution is indicated.