The Syme amputation, also known as ankle disarticulation, is performed at the level of the ankle joint while preserving the heel pad. This technique offers excellent potential for good functional outcomes in lower extremity amputations.
First described in 1843 by Sir James Syme of Edinburgh, Scotland, this procedure remains a valuable option for specific patient populations.
The technique utilizes a single long posterior heel flap. The incision begins at the distal tip of the lateral malleolus, crosses the anterior aspect of the ankle joint at the level of the distal tibia, and reaches a point just below the tip of the medial malleolus. From there, it extends downward across the sole of the foot to the lateral side, ending back at the starting point.
All structures are dissected down to the bone. To remove the tarsus, the foot is placed in marked equinus (pointed downward), and the anterior ankle joint capsule is divided. A knife is inserted into the joint space between the medial malleolus and the talus and then drawn downward to divide the deltoid ligament while protecting the posterior tibial artery. The same maneuver is repeated on the lateral side to divide the calcaneofibular ligament.
To further increase equinus positioning, a bone hook is placed on the posterior aspect of the talus, and dissection proceeds posteriorly, dividing the posterior ankle joint capsule. Dissection continues near the superior surface of the calcaneus (heel bone). The Achilles tendon is identified, exposed, and divided at its insertion on the calcaneus. Care must be taken to avoid damaging the overlying skin to prevent flap necrosis.
Using a raspatory, soft tissues are separated from the lateral and medial surfaces of the calcaneus, drawing the bone further into equinus. A subperiosteal dissection is then performed on the inferior surface of the calcaneus until the distal end of the plantar skin flap is reached.
The entire foot, except for the heel flap, is removed. The flap is retracted posteriorly, and the soft tissues around the tibia and malleoli are prepared. The periosteum is incised circumferentially 0.6 cm proximal to the joint line, and the tibia and fibula are divided at this level, ensuring the cut line passes through the center of the ankle dome. The cut surfaces of the tibia and fibula should be parallel to the ground when the patient is standing. Sharp bone edges are rounded and smoothed.
The medial and lateral plantar nerves are identified and divided proximal to the bone end. Tendons are divided and allowed to retract proximally into the leg. The posterior tibial artery and vein are isolated and ligated just above the cut distal edge of the heel flap, while the anterior tibial artery in the anterior flap is also ligated.
Minimal debridement is performed on all soft tissue attachments of the plantar muscle and fascia along the inner surface of the heel flap, preserving the intact subcutaneous fat and its septa, which are specialized pressure-tolerant tissues.
Various techniques have been employed to prevent migration of the heel pad on the stump. An effective method, known as the Wagner technique, involves drilling holes through the anterior edge of the tibia and fibula and suturing the deep fascia lining the heel flap to the bone through these holes.
The skin edge of the heel flap is then approximated to the skin edge of the anterior flap using interrupted, non-absorbable sutures, ensuring no tension is present. Protruding skin folds, often called "dog ears," may appear at each end of the suture line. These should not be removed, as they contribute to the blood supply of the heel flap and will eventually resolve under the dressing.
A long leg cast (above the knee) is applied, and a drain is placed. The drain is typically removed 24 to 48 hours after surgery.
A soft dressing can be applied and care continued as usual. However, a preferred approach is to apply a properly padded rigid dressing in the operating room at the end of the procedure. If ambulation is to be delayed until wound healing is confirmed, a simple, well-padded plaster cast is sufficient. If early ambulation is desired, or if prosthetic gait training is to be initiated later in the postoperative period, a true prosthetic cast should be applied as described below.
Apply a light sterile dressing to the wound and put on a sterile stump sock. Sterile felt pads are shaped and skived by the prosthetist to relieve pressure over the shin crest and the edges of the divided bones. The prosthetist affixes these pads to the stump sock with medical adhesive and applies the plaster cast.
Use elastic plaster for the initial wrapping to ensure good control of tension, then reinforce with conventional plaster. Compression should be gentle, maximal at the end of the stump, and gradually decrease proximally. The cast does not need to extend above the knee, as the shape of the stump and the tight fit between the stump and rigid dressing provide adequate suspension.
The end of the rigid dressing is flattened for weight bearing by pressing a board against the wet plaster. The proximal part of the cast is shaped to create a patellar bar and popliteal bulge, similar to a prosthesis that supports the patellar tendon, allowing partial loading on the patellar tendon and tibial condyles.
If needed, a lift block is added to correct leg length discrepancy, and a Syme prosthetic foot or a rubber walking heel is attached to the cast. A hip belt and suspension straps provide additional suspension.
Gait training and further postoperative care following Syme amputation are then continued.
A Syme prosthesis may utilize a suspension sleeve or a total contact socket and a prosthetic foot, with the socket being the most critical part of the prosthesis.
