(1)
Yotsuya Medical Cube, Chiyoda-ku, Tokyo, Japan
Basic Principles
The dorsum of the foot has a large number of tendons, and is a difficult place for a skin graft to take. The method of creating granulation tissue using artificial dermis and then conducting a skin graft is available as an option, but fixing the foot in place for long periods decreases the range of movement of the ankle and can induce contracture such as equinus foot.
For the reconstruction of an amputation stump using a free flap, a comparatively thin skin flap is chosen. The dorsal artery of the foot is close to the reconstruction position and muscle spasms tend to occur, so anastomosis (if possible end-to-side) to the posterior tibial artery is the preferred option.
Selectable Flaps and Surgical Procedures
Extensor digitorum brevis muscle flap (normal/reverse) + skin graftTemporal fascia flap and skin graftFree abdominal perforator (DIEP) flapArtificial dermis and skin flapGroin flapCombined free scapular/parascapular flapFree anterolateral thigh flapThe difficulty level of each surgical procedure is shown subsequent to the procedure title (e.g., Level of Difficulty: 2). The levels range from 1 to 5, with level 1 indicating a preliminary level and level 5 indicating a very advanced level.
20.1 Extensor Digitorum Brevis Muscle Flap (Level of Difficulty: 3)
Information
Vascular pedicle Lateral tarsal blood vessels (branches from the dorsal pedis artery beneath the extensor retinaculum)
Size 4.5 × 6 cm
Advantage Blood flow is stable, it is not bulky and there is no loss of function due to harvesting. Suitable for covering exposed tendons or bone of the dorsum. The vascular pedicle is beneath the extensor retinaculum of the ankle, and some distance from the area to be covered, so is often not damaged.
Disadvantage Size of muscle flap is small. Requires skin graft
Caution Incision is made slightly medial along the dorsal artery
20.1.1 Operation Procedures
Case 1
Fig. 20.1
Case 1 Procedure 1: Due to a large loss of skin from the dorsum, the extensor digitorum longus muscle is exposed.
Note However, damage doesn’t extend to the layers below the extensor digitorum longus muscle tendon. Also, there is no damage to the extensor retinaculum. Therefore the extensor digitorum brevis muscle and lateral tarsal artery are retained and an inference is made that elevation of an extensor digitorum brevis muscle flap is possible.
Procedure 2: The extensor digitorum brevis is found beneath the extensor digitorum longus muscle tendon (extensor hallucis brevis muscle and extensor digitorum brevis muscle), and the muscle flap is dissected and elevated above the periosteum from the distal part of the muscle flap on the lateral dorsum, and dissected in the direction of the dorsal artery of the foot. Following the path of the dorsal artery, when the extensor retinaculum is cut at about 2 cm, it becomes possible to see the lateral tarsal artery branching off and entering the muscle flap
Note
Turning over the muscle flap it is possible to clearly confirm the vascular pedicle on the reverse side.
Fig. 20.2
Procedure 3: The elevated tissue is taken out from beneath the extensor hallucis longus muscle tendon
Fig. 20.3
Procedure 4: The muscle flap is used to cover the exposed tendon
Fig. 20.4
Procedure 5: A split-thickness mesh skin graft is conducted above the muscle flap
20.1.2 Case 2
Fig. 20.5
Case 2: Procedure 1: Example of exposure of the extensor tendon due to skin defect of dorsum. There is no damage to the extensor digitorum brevis muscle beneath the extensor digitorum longus muscle tendon
Fig. 20.6
Procedure 2: The extensor digitorum brevis muscle is cut from the distal part of the tendon, and the bone attachment area detached from the periosteum
Fig. 20.7
Procedure 3: The separated extensor digitorum brevis muscle flap is extracted from under the extensor digitorum longus muscle tendon
Fig. 20.8
Procedure 4: The extracted muscle flap is used to cover the exposed tendon
Fig. 20.9
Procedure 5: A skin graft is conducted on the muscle flap, and a tie-over bolster dressing applied
Tips
If the incision is made in the lateral dorsum to make for an easier muscle flap harvest, the blood flow to the medial dorsum will become unstable.
The blood flow to the dorsum flows medially through the dorsal artery, and laterally through the peroneal artery. If the dorsal artery is harvested in order to elevate this muscle flap, blood flow will be limited to the peroneal artery on the lateral side. If the incision is made in the lateral dorsum, blood flow of the peroneal artery on the medial dorsum will be disrupted, and a sore can occur on the dorsum. The incision should be made slightly medial of the area surrounding the dorsal artery.
20.2 Reverse Extensor Digitorum Brevis Muscle Flap (Level of Difficulty: 3)
Information
Vascular pedicle Lateral tarsal blood vessels (branches from the dorsal pedis artery beneath the extensor retinaculum)
Size 4.5 × 6 cm
Advantage Blood flow is stable, it is not bulky and there is no loss of function due to harvesting. Suitable for covering exposed tendons or bone of the dorsum. The vascular pedicle is beneath the extensor retinaculum of the ankle, and some distance from the area to be covered, so is often not damaged.
Disadvantage Size of muscle flap is small. Requires skin graft.
Caution Incision is made slightly medial along the dorsal artery. The connection branch between the dorsal artery and plantar artery must be left intact
Refer to Section of
20.2.1 Operation Procedures
Fig. 20.10
Procedure 1: Skin defect of distal dorsum due to amputation of great toe. The X marks the path of the dorsal artery and the solid line marks the incision line
Fig. 20.11
Procedure 2: While gradually detaching the dorsal pedis vessels, the extensor digitorum brevis muscle beneath the extensor digitorum longus muscle tendon is gradually detached from the distal end and severed
