- 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 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:
- this amputation has enough length and necessary muscle attachments to remain functional with shoe modifications;
- need to reduce peak plantar pressure on the distal stump;
- extended foot plate:
- extended carbon fiber foot plate
- 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;
- toe filler: custom molded foam pad or lamb's wool can fill the distal empty toe portion of the shoe;
- rigid rocker bottom sole
- reference: Can partial foot prostheses effectively restore foot length?
Transmetatarsal amputation in patients with peripheral vascular disease.
Transmetatarsal amputation for infection or gangrene in patients with diabetes mellitus.
The transmetatarsal amputation in peripheral vascular disease.
Transcutaneous Doppler ultrasound in predictions of healing and selection of surgical levels.
Symes amputation, the technical details essential for success.