Equipment
The choice of surgical instruments for transmetatarsal amputation (TMA) is left to the surgeon's discretion. Equipment that may be used includes the following:
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Scalpel with blades
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Dissection and cutting scissors
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Retractors and handheld clamps
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Needle holders, suture material (absorbable and nonabsorbable), and forceps (fine and toothed)
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Diathermy device
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Bone instruments (eg, saw, bone nibblers, osteotomes, mallet, and curettes)
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Irrigation
Patient Preparation
TMA is performed with general anesthesia or regional anesthesia, depending on the patient's level of anesthetic risk.
The patient is placed in a supine position on the operating table, with a tourniquet around the upper thigh. A considerable amount of wool should be placed under the tourniquet cuff, and a good amount of adhesive should be applied to keep the tourniquet in place.
Full sterile preparation is undertaken with antimicrobial wash and disinfectant. The ulcerated area is covered with a surgical glove. All necessary measures for protecting the supposed healthy tissue are taken before the surgical knife is applied to the skin.
The leg is elevated, and the blood is milked out of the limb and back up the vascular tree. The tourniquet cuff is inflated, usually to a pressure of 200-300 mm Hg.
Monitoring & Follow-up
Rehabilitation must be addressed. TMA results in the loss of some of the area normally used for weightbearing. Consequently, load distribution on the foot becomes unbalanced, and the remaining foot tissues are subjected to a higher-than-normal mechanical load. The healing foot is therefore under increased pressure, which is detrimental to skin healing, as well as to the biomechanics of motion. It should also be noted that neuropathic patients have a decreased level of stability and an increased incidence of falls.
Mechanical problems after TMA are due to the decrease in plantarflexion; thus, the patient typically experiences this instability when mobilizing. Decreased plantarflexion reduces the overall "support movement," which is defined as the sum of hip, knee, and ankle extensor movements and represents the total limb pattern involved in pushing away from the ground. [5]
The solutions to these mechanical problems are as follows:
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Regular sensory check for patients with diabetes, neuropathy, or both - Patients with reduced sensation need extensive education regarding care
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Use of orthotic devices - Temporary postoperative devices include plaster of Paris (if the foot is not weightbearing), walking splints or boots, definitive footwear (after the surgical wound has healed), custom-made footwear (eg, steel implants in the soles of shoes), and shortened shoes
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Top image shows fish-mouth incision on plantar surface; bottom image shows final appearance of stump.
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Fish-mouth incision on dorsal surface of foot.
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Metatarsal heads have been osteotomized.
