SYME’S AMPUTATION

INDICATIONS Lesions confined to the forefoot only, when the operator is fairly skilled.

CONTRAINDICATIONS (1) Arterial disease, unless this is strictly confined to the distal part of the foot. One and preferably both ankle pulses should be present. (2) The need for an elegant prosthesis. A woman is likely to prefer a below knee amputation. (3) Infection. Syme’s amputation has a special posterior flap and is not suitable for delayed primary closure. (4) A very inexperienced operator. (5) This is not a good amputation for leprosy.

METHOD For the general method, see Section 56.1. Apply a tourniquet to the patient’s thigh (3.8), and let his ankle hang over the end of the table. Stand at the end of it facing his foot.

Mark out the flaps with methylene blue. Hold his ankle at 90. Start the incision at the distal tip of his lateral malleolus. Bring it over the front of his ankle, level with the distal end of his tibia to a point one finger’s breadth inferior to the tip of his medial malleolus. Then, bring the incision under the sole of his foot to the tip of his medial malleobus. Cut all structures down to the bone.

Forcibly plantar flex his foot and cut all anterior structures down to the bone. Put a knife into his ankle joint between his medial malleolus and his talus and cut his deltoid ligament. Do the same on the lateral side and cut his calcaneofibular ligaments.

Put a bone hook posteriorly in his talus to plantar flex his foot even more.

Using a new, sharp scalpel blade, dissect the tissues away from the medial and lateral sides of his talus and calcaneus, keeping as close to the bone as you can, f possible within the periosteum. Then cut his calcaneus out of his heel. Work at it from all sides keeping very close to the bones. When you get tired of one approach, start from another. This is the most difficult and the most critical part of the operation.

Pull his talus and calcaneus forward with a bone hook. Dissect posteriorly, and cut the posterior capsule of his ankle and his Achilles tendon. Then dissect subperiosteally round the ball of his heel, so as to free his calcaneus and reach the first incision on his sole. As you do so, steadily dislocate his foot downwards more and more, until you reach the distal end of the plantar skin flap and finally free it from his ankle.

CAUTION! (1) Keep within the periosteum very close to the bone: as you dissect his calcaneus out of his heel flap, or you will cut his posterior tibial and peroneal arteries which are very close to the back of the joint capsule. If necessary, remove his calcaneus piece by piece. (2) Don’t trim away any muscle or fat in the heel pad, because he needs it to walk on. (3) Keep close to the bone, and don’t button hole the heel flap.

Remove his whole foot except for the heel flap.

Dissect the heel flap from his malleoli, and reflect it posteriorly. Saw off his malleoli and the articular cartilage of his tibia in a single cut. Make sure that the ends of his tibia and fibula are accurately horizontal, so that he can bear weight squarely on the stump.

CAUTION! (1) The cut surfaces of his bones must parallel to the ground when he stands. (2) If you are amputating in a child, don’t destroy his distal tibial epiphysis.

Round and smooth all the sharp corners of his tibia and fibula. Cut his medial and lateral plantar nerves proximally.

Pull on any tendons you can see, cut them and let them retract proximally into his leg.

Tie and cut his posterior tibial artery and vein just proximal to the cut distal edge of the heel flap. Tie his anterior tibial artery in the anterior flap.

Using a step incision cut his Achilles tendon about 10 cm proximal to the heel flap. This will prevent the heel stump displacing. If you don’t do this, his Achilles tendon is apt to pull up the back of the stump. Cut it high up, or you may injure his posterior tibial vessels.

Release the tourniquet, and control bleeding. Bring his heel flap forward to cover the ends of the bones.

CAUTION! (1) Don’t remove the dog ears, however big. They carry an important share of the flap’s blood supply and will disappear later. (2) Prevent the heel pad from tilting out of alignment with the patient’s tibia-this is a real disaster! Apply two long U–shaped strips of strapping as in C, Fig. 56-14. Put the first piece on starting below his knee posteriorly, bring it round the flap, and then anteriorly, so as to flex the flap over the stump. Apply the second strip from one side to the other. Keep these strips in place for at least three weeks, and replace them as necessary.

POSTOPERATIVE CARE FOR A SYME’S AMPUTATION

Check the strapping daily, to make sure that the patient’s heel pad is centred over his tibia. Adjust it if necessary.

At 2 weeks reapply the strapping, and put on a well moulded cast round the stump. He should not bear weight yet.

At 6 weeks take the mould for the prosthesis. By now the stump has usually stuck firmly enough to the tibia to bear weight inside a cast, so apply a new one and let him bear weight on it.

At 10 to 12 weeks he is ready for his definitive prosthesis, either an elephant boot, or a more sophisticated one.