- Discussion:
- popularized by McKittrick et. al. 1949 and by Pedersen and Day 1954
- indicated for trauma, tissue loss, infection, and gangrene (limited to toes and not the web space in diabetics);
- TMA requires shoe modifications & inserts w/ forefoot space replacement.
- indicated for gangrene or infection involving multiple digits or involving the great toe;
- amputation may be done for gangrene extending a short distance on dorsal skin past the metatarsal phalangeal crease, provided that
plantar skin is not comprimised;
-
contraindications:
- include forefoot infection, cellulitis, lymphangitis, or dependent rubor involving the dorsal forefoot proximal to metatarsal phalangeal crease;
- also contraindicated are any gangranous changes on the plantar skin extending proximal to the MP crease;
- gait function:
- this results in a bony anterior section which can be difficult to fit;
- arch often flattens out over time causing further wt bearing problems;
- toe filler may be sufficient, but often molded arch support is added;
- extended steel shank adds protection during a role over;
- Technique:
- skin incision is designed that utilizes a total plantar flap;
- slightly curved dorsal forefoot incision is carried from side to side at the level of the mid-metatarsal shafts;
- begin & end incision at the midpoint of the lateral aspect of foot;
- incision extends to the base of the toes medially and laterally in midplane axis of the foot;
- plantar incision begins at or just proximal to the MP crease;
- because greater cross sectional diameter to be covered with skin medially, incision is slightly longer on medial than lateral side;
- reflect the plantar flap distally to the level of bone section;
- line of incision will be slightly distal to anticipated line of bone division;
- skin incision is carried down thru soft tissues to metatarsal shafts, and each shaft is transsected with an air driven oscillating saw approximately
5 mm to 1 cm proximal to the skin incision;
- plantar tissues of the distal forefoot are separated from metatarsal shafts with a scapel;
- tissues of the plantar flap are thinned sharply, excising exposed tendons and leaving the underlying musculature attached to posterior plantar flap;
- posterior plantar flap is then rotated dorsally for closure after tayloring or thinning as required to achieve good skin coaptation;
- simple closure with a deep layer of absorbable interrrupted sutures and a skin closure using a vertical matress technique;
- if necessary a closed suction drain may be used;
- well padded short leg plaster cast is the best postoperative dressing since it will control edema and prevent stump trauma;
- early ambulation after transmetatarsal amputation is not preferred;
- if wound healing is satisfactory at the first postoperative cast change, 7 to 10 days after surgery;
- rigid dressing is used until the transmetatarsal flap is well healed, usually 3 to 4 weeks after surgery;
- Shoe Modifications:
- includes incorporation of a steel shank into the sole of shoe to allow normal toe off ambulation;
- spring steel shank reproduces the action of longitudinal arch of foot during ambulation;
- custom molded foam pad or lamb's wool can fill the distal empty toe portion of the shoe;
Transmetatarsal amputation in patients with peripheral vascular disease.
Transmetatarsal amputations. Schwindt CS: Orthop Clin North Am 1973;4:31-44.
Transmetatarsal amputation for infection or gangrene. McKittrick LS, Risley TS: Ann Surg 1949;130:826-842.
Transcutaneous Doppler ultrasound in predictions of healing and selection of surgical levels. Wagner FW: Clin Orthop Rel Res 1977;162:110-121.
Symes amputation, the technical details essential for success. Harris RI: J Bone Joint Surg (Br) 1956;28B:614-629.
