Can The Extensor Digitorum Brevis Muscle Flap Help Salvage A Diabetic Limb With Osteomyelitis?
These authors discuss the use of the distally-based, extended extensor digitorum brevis muscle flap for limb salvage in a patient with diabetes and osteomyelitis of the great toe.
The extensor digitorum brevis muscle flap has been an option for local soft tissue reconstruction since the 1970s.1 Since that time, there has been an increased utilization of the muscle flap for a variety of applications including coverage of foot and ankle defects.2-12
Of particular interest is the extended, distally based extensor digitorum brevis muscle flap for salvage of the hallux.7,13,14 Since the hallux is vital in maintaining normal foot function, it would be ideal to preserve the hallux. Treatment becomes difficult when there is a significant post-surgical tissue defect along the operated hallux that is not amenable to skin grafting.
Reconstruction of the distal foot, especially the toe, has posed a particularly challenging problem. There are few local options available for the distal forefoot and toes such as the fillet of toe, the dorsometatarsal first web flap, and the distally-based dorsalis pedis flap. However, these options have significant donor site morbidity and a limited arc of rotation.
The proximity and advantages of the extensor digitorum brevis muscle makes it an option for coverage of the toes. The flap is useful due to the muscle’s size and thinness, consistent vascular anatomy, large vessel size, ease of dissection, minor donor site morbidity, arc of rotation and length of the pedicle. The limited bulk of the muscle allows for primary closure of the donor site. Since the muscle is a secondary toe extensor, it is expendable without a functional deficit. In terms of a reverse flow, the increased arc of rotation and length of the pedicle permits coverage of defects of the toes. Muscle flaps are preferred in the management of complicated wounds involving osteomyelitis. These flaps are pliable, contour to defects, fill dead space, provide improved tissue ingrowth, enhance the local delivery of antibiotics and revascularize underlying bone.
A Closer Look At The Relevant Anatomy
The extensor digitorum brevis muscle is a thin muscle located on the dorsum of the foot. It originates from the sinus tarsi and the dorsolateral surface of the calcaneus. It courses distally and medially, finally terminating on the base of the hallux and along the lateral aspect of extensor digitorum longus tendons of the second through fourth digits. The muscle shape is trapezoidal and its dimensions are typically 5 cm x 6 cm with a surface area of 19 to 34 cm2.4
The dorsalis pedis artery is a continuation of the anterior tibial artery, which courses inferior to the extensor retinaculum. The medial and lateral tarsal arteries branch from the dorsalis pedis artery.3 The medial tarsal artery travels medially and deep to the abductor hallucis muscle to connect with the medial plantar artery. The lateral tarsal artery runs laterally and situates itself along the deep surface of the extensor digitorum brevis muscle, serving as the muscle’s main supplier when present.