Named Amputations — Syme, Chopart, Lisfranc, Boyd, Pirogoff and the Levels of Limb Amputation

Most named amputations are eponymous disarticulations or bone cuts at a fixed level of the foot. A widely used classification groups the foot amputations as forefoot (toe disarticulation, ray, transmetatarsal), midfoot (Lisfranc, Chopart) and hindfoot (Syme, Boyd, Pirogoff, modified Pirogoff), and then continues with the transtibial, through-knee, transfemoral and hip levels.

The same classification separates distal (minor) amputations, where the tibial weight-bearing stump is preserved, from proximal (major) amputations, where it cannot be preserved. The first amputation in a diabetic foot should preferably be a minor (distal) one. Some authors, however, treat the Syme amputation as a major amputation, so check the definition a question uses.

Toe disarticulation is the commonest and least invasive amputation. A ray amputation removes a toe together with part of its metatarsal, which gives a better chance of clearing infected margins. Indications for a ray amputation include wet or dry toe gangrene, osteomyelitis of the metatarsal head or proximal phalanx, septic arthritis of the metatarsophalangeal joint and gross toe infection.

A transmetatarsal amputation (TMA) is considered when gangrene or infection is confined to the forefoot. Suggested inclusion criteria for a ray amputation include one or two palpable pedal pulses, ankle-brachial index of at least 0.8 and toe-brachial index of at least 0.7; the transmetatarsal level uses the same inclusion criteria.

Both are midfoot disarticulations. Lisfranc amputation is a disarticulation through the tarsometatarsal joint. Chopart amputation is a disarticulation through the talonavicular and calcaneocuboid joints, leaving only the talus and calcaneum behind. Lisfranc is therefore more distal; Chopart leaves a shorter foot.

The primary indication is extensive soft tissue loss of the forefoot, often from trauma, although they can be elective. Because the residual limb is longer than a below-knee stump, these patients can usually walk short distances without a prosthesis. In diabetic foot infection they are rarely performed because of a high failure rate, and reports describe a substantial proportion needing a later below-knee amputation.

Syme amputation (ankle disarticulation) is a disarticulation of the tibiotalar joint with resection of the malleoli, using the heel pad to cover the end of the tibia. Preserving the heel pad allows end-bearing: patients can bear weight on the stump, and the walking energy cost is only slightly above normal. It is relatively rare, about 1 to 2% of lower-limb amputations.

• Indications: severe foot deformity, chronic infection, malignancy, localised trauma, and congenital anomalies such as longitudinal fibular deficiency and proximal femoral focal deficiency.
• Selection in diabetes: at least a palpable posterior tibial pulse and an ankle-brachial index above 0.5.
• Disadvantages: unstable calcaneal flap, risk of devascularisation of the flap when the calcaneum is dissected out, and a shorter stump with leg-length discrepancy, which makes barefoot walking difficult.
• Heel-pad migration is prevented by supramalleolar resection or Achilles tenodesis.

The Boyd and Pirogoff amputations were designed to give better results than a Syme amputation. Both retain the calcaneum (wholly or in part) and achieve tibio-calcaneal bony fusion, which stabilises the flap, reduces devascularisation (the calcaneum is not dissected out), minimises limb-length discrepancy and permits full weight-bearing with less need for a prosthesis. Pirogoff amputation, described by Nicolas Pirogoff in 1864, partially preserves the calcaneus and is suited to necrosis distal to the Lisfranc and Chopart joints with preserved blood flow in the calcaneus.

Below-knee (transtibial) amputation is one of the commonest, about 47% of all lower-limb amputations, and is done most often for peripheral arterial disease, diabetes-related complications and trauma. Preserving the knee gives better function: walking costs only 10 to 40% more energy than normal.

Above-knee (AKA) and transfemoral amputations together account for about 27% and are often done in emergencies for critical limb ischaemia or severe infection. Losing the knee raises the energy cost of walking to 60 to 100% above normal, and the prosthesis is more complex. Knee disarticulation (2 to 3%) is chosen when the knee cannot be saved but the femur is intact, and its energy cost sits between BKA and AKA. Hip disarticulation and hemipelvectomy are rare (under 1%), usually for malignancy, severe trauma or life-threatening infection.

• Lisfranc = tarsometatarsal joint; Chopart = talonavicular + calcaneocuboid. Do not swap them.
• Syme = ankle (tibiotalar) disarticulation with heel-pad cover. The malleoli are resected.
• Boyd and Pirogoff add tibio-calcaneal fusion; Pirogoff partially preserves the calcaneus.
• Transmetatarsal amputation → equinovarus. Treated with Achilles lengthening and split tibialis anterior transfer.
• Distal (minor) amputations preserve the tibial weight-bearing stump; BKA and above are major.
• Syme in the diabetic foot needs a palpable posterior tibial pulse and ABI above 0.5.
• Energy cost rises with level: Syme lowest, BKA 10 to 40%, AKA 60 to 100%.