Foot & Ankle Amputation Levels
As the amputation moves proximally (Lisfranc → Chopart), the dorsiflexor (tibialis anterior, long extensors) and everter (peroneal) insertions are lost, leaving the intact triceps surae and tibialis posterior unopposed. The result is a powerful equinovarus deformity that ulcerates the stump if not corrected.
Rebalance at the index operation: tendo-Achilles lengthening (to counter equinus) and, for Chopart, tibialis anterior tendon transfer to the talus/midfoot (to restore dorsiflexion). Failure to rebalance is the classic reason a Chopart amputation fails.
The Levels
Forefoot Levels
- Toe amputation: for isolated digital gangrene/osteomyelitis; well tolerated. Loss of the great toe most affects push-off and balance.
- Ray amputation: toe + its metatarsal (e.g. for deep infection tracking up a ray). Border rays (1st, 5th) tolerate ray resection well; central rays narrow the foot.
- Transmetatarsal amputation (TMA): division across all metatarsals (ideally leaving a slightly longer first metatarsal). Good functional level; preserve a robust plantar flap and lengthen the Achilles if there is equinus to prevent forefoot pressure on the stump.
Principles & Decision-Making
Three competing goals govern level selection: preserve functional length (better gait, less energy cost, end-bearing), ensure the wound heals (vascular supply, infection control, soft-tissue coverage), and maintain muscle balance (avoid equinovarus). The most distal level that will reliably heal and stay balanced is usually best.
- Healing assessment (use thresholds, not just pulses): arterial inflow is the dominant predictor - an ankle-brachial index helps but is falsely elevated by calcified, incompressible vessels in diabetes, so toe pressures (greater than ~30 mmHg) and transcutaneous oxygen tension (TcPO2 greater than ~30 mmHg) are more reliable healing predictors. Add nutritional/immune status (classic thresholds serum albumin greater than 3.0 g/dL and total lymphocyte count greater than 1,500/mm³), glycaemic optimisation, and infection control (debridement, source control, antibiotics).
- Soft tissue: a durable, sensate, well-vascularised plantar/heel flap is the goal; the plantar skin is the ideal weight-bearing surface.
- Balance: plan tendon rebalancing (Achilles lengthening, tibialis anterior transfer) for proximal partial-foot levels.
- The partial-foot vs transtibial decision: when a partial foot amputation is unlikely to heal or remain functional, a transtibial amputation with a good prosthesis may give better, more predictable function - a genuine shared decision.
Beyond proximal-level equinovarus, the forefoot levels have their own biomechanical trap that examiners test — the windlass mechanism and load transfer:
- The windlass mechanism is the tensioning of the plantar aponeurosis as the hallux dorsiflexes at toe-off, which raises the medial arch and stiffens the foot into a rigid lever for push-off. Amputating the great toe / first ray abolishes the windlass, weakening push-off and destabilising the medial column.
- Removing a toe or ray transfers weight-bearing load to the remaining metatarsal heads, producing transfer-lesion ulceration under the adjacent heads — the reason a single ray amputation in a neuropathic foot so often precedes the next ulcer.
- Practically: preserve first-metatarsal length (leave the first ray slightly longer at TMA), keep the metatarsal parabola/cascade smooth to avoid a prominent residual head, and where possible amputate the hallux through the base of the proximal phalanx (retaining the flexor hallucis brevis/sesamoid-plantar-plate attachment) rather than a bare MTP disarticulation, to keep some windlass and first-ray balance.
So the forefoot question is "what happens to push-off and to the load on what remains," just as the midfoot question is "what happens to muscle balance."
Prosthetic & Orthotic Considerations
Each level trades length for the soft-tissue envelope and lever arm the patient keeps - and therefore for how much a prosthesis or orthosis must restore. Energy cost of walking rises as the level moves proximal, but partial-foot levels remain far more efficient than a transtibial amputation, which is a major argument for preserving a durable, balanced foot.
- Toe / ray: usually only a shoe filler and a stiff/rocker insole; great-toe or first-ray loss is managed with a rigid rocker-sole shoe to substitute for lost push-off.
- Transmetatarsal (TMA): a custom insole with a toe filler and a rigid rocker-bottom sole (or a clamshell ankle-foot orthosis) restores the lever arm and offloads the distal stump; an equinus contracture must be prevented (Achilles lengthening) or the distal stump is overloaded.
- Lisfranc / Chopart: require the foot to be plantigrade and balanced first, then a solid-ankle clamshell AFO or custom partial-foot prosthesis with a forefoot filler; an unbalanced (equinovarus) stump cannot be braced successfully.
- Syme: a Syme prosthesis that is end-bearing (load through the heel pad) with a window or expandable design to admit the bulbous distal end; durable and low-energy, though cosmesis at the ankle is a trade-off.
TRTLCSPartial Foot Levels (distal → proximal)
Hook:Toe, Ray, TMA, Lisfranc, Chopart, Syme - more proximal = more equinovarus.
Energy Cost and Complications
Energy cost of walking rises with level
A central argument for preserving a durable, balanced foot is the energy cost of gait, which climbs the more proximal the amputation. Partial-foot amputees walk at close to normal energy cost; the step up to a transtibial amputation adds roughly a fifth to a quarter more energy than normal walking, and a transfemoral amputation far more again (with correspondingly slower self-selected walking speed). The implication is consistent with the outcome data: a partial foot that will heal and stay plantigrade is metabolically cheaper to walk on than a more proximal level — but only if it is actually functional.
Complications
- Note
- The hallmark of proximal partial-foot (Chopart more than Lisfranc) — prevent with rebalancing at the index operation
- Note
- Dominant problem in the dysvascular/diabetic foot; optimise perfusion, nutrition, glycaemia and infection before and after surgery
- Note
- Common after dysvascular partial-foot amputation — counsel the patient that a single operation may not be the end point
- Note
- A poorly anchored or insensate heel pad migrates and ulcerates, undermining the end-bearing stump
- Note
- Handle nerves with traction-neurectomy technique; phantom sensation and pain can follow any amputation
- Note
- From pressure on an unbalanced or insensate stump — offload with the right prosthesis/orthosis and treat the deforming force
Handling the divided nerves is no longer just "cut and let it retract." Three options, increasingly performed at the index amputation to prevent symptomatic neuroma and phantom/residual-limb pain:
- Traction neurectomy (the traditional default): draw the nerve down under gentle tension and divide it sharply so the cut end retracts away from the weight-bearing surface and the scar — simple but a symptomatic neuroma can still form.
- Targeted muscle reinnervation (TMR): coapt the transected major nerve to a nearby expendable motor nerve branch, giving the regenerating axons a muscle target instead of a disorganised neuroma — shown to reduce neuroma and phantom pain (and, in major limbs, to enable myoelectric prosthetic control).
- Regenerative peripheral nerve interface (RPNI): implant the nerve end into a free autologous muscle graft that the axons reinnervate, similarly damping neuroma formation.
Combine with multimodal perioperative analgesia (regional/peripheral nerve or epidural blockade and neuropathic agents) to reduce the incidence and severity of phantom limb pain. This is the contemporary answer to the "how do you manage the nerves / prevent phantom pain?" follow-up.
Evidence Base
The two systematic reviews below (both checked against PubMed, from the Dillon/Quigley group) frame the central decision. Together they say: partial-foot amputation preserves the limb but carries high rates of delayed healing and ipsilateral reamputation, while transtibial amputation carries higher mortality — almost certainly because transtibial candidates have more advanced systemic disease, not because the operation is more dangerous. Crucially, quality of life and mobility look similar between the two, so QoL alone does not justify struggling to preserve a marginal foot — the level should be driven by whether it will actually heal and function. The evidence base is observational and heterogeneous, so the decision remains individualised and shared.
Outcomes of dysvascular partial foot amputation and how these compare to transtibial amputation: a systematic review for the development of shared decision-making resources
- Systematic review of 29 studies on dysvascular partial foot amputation (PFA) versus transtibial amputation (TTA)
- A large proportion of PFA patients experience delayed wound healing and ipsilateral reamputation
- TTA carries higher mortality than PFA - likely reflecting more advanced systemic disease in TTA candidates
- Mobility and quality of life may be similar between PFA and TTA
Quality of life in persons with partial foot or transtibial amputation: A systematic review
- Systematic review comparing quality of life in partial foot versus transtibial amputation
- Available evidence suggests quality of life may be similar between the two levels
- Small differences are unlikely to be clinically meaningful
- Evidence is limited - level decisions should be individualised
Viva Scenarios
Practise clinical reasoning and management decisions out loud
“A patient who had a Chopart amputation returns with an ulcer over the front of the stump and the foot pointing down and in. What has happened and how is it prevented/treated?”
“A patient with diabetes and peripheral vascular disease has forefoot gangrene. How do you decide the amputation level, and how do you counsel them about a partial foot versus a below-knee amputation?”
Guidelines, Registries & Global Practice
Global Practice Picture
Partial foot amputation is performed worldwide, most often for the dysvascular/diabetic foot. The internationally consistent principles are: choose the most distal level that will reliably heal and stay balanced; rebalance proximal partial-foot levels to prevent equinovarus; secure a durable plantar/heel weight-bearing surface; and frame the partial-foot-versus-transtibial choice as a shared decision based on heal-ability and function.
Side-by-Side Synthesis
- Joint/bone
- Digit / metatarsal
- Key issue
- Great-toe loss affects push-off
- Joint/bone
- Across metatarsals
- Key issue
- Achilles lengthening for equinus
- Joint/bone
- Tarsometatarsal
- Key issue
- Early equinovarus tendency
- Joint/bone
- Midtarsal
- Key issue
- Strong equinovarus - rebalance (Achilles + TA transfer)
- Joint/bone
- Ankle disarticulation
- Key issue
- Heel pad-dependent, end-bearing
- Joint/bone
- Calcaneo-tibial fusion
- Key issue
- Durable end-bearing stump
Levels (distal → proximal)
- Toe / Ray
- Transmetatarsal (TMA)
- Lisfranc (tarsometatarsal)
- Chopart (midtarsal); Syme (ankle); Pirogoff/Boyd
Principles
- Most distal level that heals + stays balanced
- Proximal levels → equinovarus (rebalance)
- Achilles lengthening + tibialis anterior transfer
- Durable plantar/heel weight-bearing surface
Decision
- Healing dominant in dysvascular/diabetic foot
- PFA: high reamputation; TTA: higher mortality (sicker)
- QoL/mobility similar PFA vs TTA
- Shared decision on level