Foot Transmetatarsal Amputation

Transmetatarsal Amputation involves removal of the forefoot at the level of the metatarsal shafts with the aim of maximizing limb function by maintaining a significant portion of the foot. The procedure was first described by Bernard and Heute for the treatment of trench foot and was later popularized by McKettrick and colleagues as a limb salvaging procedure used for severe diabetic foot complications.

The Transmetatarsal Amputation is considered preferable to amputation through the hindfoot or traditional below knee amputation (BKA) and is generally accepted as an effective salvage procedure in cases of forefoot infection, gangrene, and chronic ulceration. 

See Also: Foot Anatomy

Transmetatarsal Amputation Advantages

1. Preservation of a viable weight-bearing platform allowing early ambulation,
2. Enabling the patients to maintain their independence, whilst maintaining a more acceptable appearance as it may be disguised somewhat with footwear.
3. A partial foot amputation also results in less expenditure of energy during ambulation than more proximal amputations, facilitating mobility and independence.
4. Transmetatarsal Amputation procedure proves to be the most favourable option with regard to patient satisfaction and function.

Transmetatarsal Amputation Procedure Steps

• To fashion long plantar and short dorsal full-thickness flaps, begin the dorsal incision at the level of intended bone section on the anteromedial aspect of the foot and curve it slightly distal to the level of bone section to reach the midpoint of the lateral side of the foot. Begin the plantar incision at the same point as the dorsal, carry it distally beyond the metatarsal heads, and curve it proximally to end at the midpoint of the lateral side of the foot. Because of the greater cross-sectional diameter to be covered with skin medially, the incision is slightly longer on the medial than on the lateral side. Fashion the plantar flap to include the subcutaneous fat and a layer of plantar muscles.
• Remove the toes at the metatarsophalangeal joints, and section the metatarsals in a beveled fashion dorsal-distal to plantar-proximal at the junction of the middle and distal thirds. The metatarsals should be removed in a cascading fashion with the second metatarsal osteotomy only a few millimeters shorter than the first metatarsal, while each successive cut is 2 to 3 mm shorter than the previous medial metatarsal. The fifth metatarsal should be even shorter (4 to 5 mm shorter than the fourth). Always use a power saw to resect the metatarsal to try to prevent subsequent bony overgrowth. Use a rongeur and rasp to smooth any bony prominences. If infection is present distally, try not to violate any abscess, leaving the metatarsophalangeal joint intact.
• Identify the nerves, and divide them well proximally so that their cut ends fall proximal to the end of the bones.
• Divide the tendons under tension so that they retract into the foot. As an alternative, suture the flexor and extensor tendons to each other to form a myoplasty. A drain may be used as necessary.
• Bring the long plantar flap over the ends of the bones, and suture it to the dorsal flap with interrupted nonabsorbable sutures. Be careful about “contouring” skin tags at the medial and lateral edges because this may jeopardize the blood supply to the flap. This excessive tissue disappears with time.
• Apply a light compressive dressing, and place the foot in a carefully padded posterior splint with the ankle in neutral to slight dorsiflexion.

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Aftercare

• Protect the amputation site with a sterile dressing for 12 to 16 days.
• Remove the sutures in dysvascular patients at 21 to 23 days, unless the wound has obviously healed sooner. Protected weight bearing usually is not needed.
• When the edema has subsided, ambulation in a supportive, soft-soled, accommodating shoe is allowed.

References & More

1. McCallum R, Tagoe M. Transmetatarsal amputation: a case series and review of the literature. J Aging Res. 2012;2012:797218. doi: 10.1155/2012/797218. Epub 2012 Jul 3. PMID: 22811912; PMCID: PMC3397208. Pubmed
2. Schwindt CD, Lulloff RS, Rogers SC. Transmetatarsal amputations. Orthopedic Clinics of North America. 1973;4(1):31–42. [PubMed]
3. McKettrick LS, McKettrick JB, Risley TS. Transmetatarsal amputations for infection or gangrene in patients with diabetes mellitus. Annals of Surgery. 1949;130:826–842. [PubMed]
4. Deldar R, Cach G, Sayyed AA, Truong BN, Kim E, Atves JN, Steinberg JS, Evans KK, Attinger CE. Functional and Patient-reported Outcomes following Transmetatarsal Amputation in High-risk Limb Salvage Patients. Plast Reconstr Surg Glob Open. 2022 May 25;10(5):e4350. doi: 10.1097/GOX.0000000000004350. PMID: 35646494; PMCID: PMC9132523. Pubmed