Toe Amputation Technique

In any toe amputation, thorough assessment of the neurovascular status of both limbs is essential. In Australia, this includes a preoperative assessment with duplex ultrasonography (US), even in a patient with all pulses intact. Consultation with a vascular surgeon may be worthwhile.

In a retrospective study that reviewed 333 toe and foot amputations with the aim of determining clinical factors associated with postamputation wound healing, Stone et al found that toe pressures were superior to duplex US parameters for predicting healing in this setting. ^[13] Preamputation toe pressures of 47 mm Hg and above were associated with wound healing, and no other noninvasive vascular studies predicted healing in the presence of confounding factors. The authors suggested that toe pressures should be routinely obtained before toe amputation.

The amputation should be performed at a level that makes anatomic sense, provides appropriate treatment for the patient’s circumstances, and minimizes the risk that further intervention will be required in the future. In all cases, the specimen should be sent for pathologic examination.

After informed consent has been obtained and the patient has been adequately anesthetized, a sterile field is set up so that the surgeon has access to the entire foot on the affected side. As noted (see Periprocedural Care), antibiotic prophylaxis should be considered if the patient is not already on regular antibiotics.

Steps common to all toe amputations

Incision lines are marked on the skin as appropriate for the planned amputation (see the images below). For a partial toe amputation, a plantar-based flap is commonly used. However, several other possibilities exist (eg, dorsal flap, side-to-side flap, and fish-mouth flap). The most important principles are to ensure that the flap is viable before closure and to perform a tension-free repair. For a disarticulation or a transmetatarsal amputation, a long plantar flap is the best choice.

All necrotic tissue is debrided. If infection is present, the tendon sheaths must be drained of any purulent material (which often tracks along them). Microbiology samples may be sent for culture and sensitivity testing. Neurovascular bundles are ligated or cauterized as they are dissected.

If the wound is left open, many dressing options are available. Commonly, the wound is loosely packed with gauze soaked in saline or povidone-iodine (though there is only limited evidence to support the latter). Other alternatives are available, such as calcium-alginate fiber. A nonstick dressing (eg, paraffin gauze) over the top is helpful for holding the packing in place. Generous amounts of cotton wrapping are applied (particularly over potential pressure areas), and a crepe bandage is applied to finish the dressing (see the image below).

Partial toe amputation with osteotomy

For amputation of one of the medial two toes, preservation of the base of the proximal phalanx is beneficial, but for different reasons in each toe. In a hallux amputation, preservation of the base of the phalanx preserves the flexor hallucis brevis (FHB) insertion, and this helps maintain stability during terminal gait phase. ^[14] In a second-toe amputation, the retained segment helps maintain the position of the hallux on that foot, preventing gross hallux valgus (which, in turn, could predispose to development of a pressure area).

For the lateral three toes, virtually no functional loss is experienced with either partial amputation or disarticulation, and foot architecture is minimally disturbed. ^[15]

Dissection is carried down to the periosteum, and a bone cutter or pneumatic saw is used to perform the osteotomy at the appropriate level. It is important to be mindful of tendon insertions and to consider the biomechanical effects that sacrificing these will have; disruption may create a cycle whereby further surgical intervention will be needed.

Disarticulation of toe

Dissection is carried down to the joint capsule, the capsule is completely incised, and the distal segment is removed (see the images and the video below).

Classically, a curette, a burr, or another instrument is then employed to remove the cartilage from the remaining joint surface (see the image below) as an aid to healing (because cartilage is avascular). However, some authors have disputed the necessity of this measure. ^[16] After disarticulation of the great toe, suturing the long extensor tendons to the dorsal joint capsule will elevate the metatarsal head.

Ray amputation

The operation is tailored to the burden of disease, ranging in extent from the removal of a single toe and its corresponding metatarsal to removal of the lateral four toes and their metatarsals. The latter amputation is functionally superior to a transmetatarsal amputation ^[16] and is preferable, provided that the hallux is free of disease.

Ray amputation of the hallux disrupts the medial column of the foot and should be performed only after careful consideration. The removal of a single metatarsal in the middle of the foot (ie, the second, third, or fourth metatarsal) results in a V-shaped wedge, which again maintains good function. However, because of the narrow forefoot that results from middle-ray amputation, shoe-fitting can be difficult, and forefoot equinus often develops.

Adequate skin and soft tissue for coverage can be obtained by removing an adequate amount of bone. Small case series have shown that primary closure with irrigation is better than leaving the wound open, even in the presence of infection. ^[16]

Transmetatarsal amputation

When trauma, gangrene, or other pathology is confined to the toes and does not involve the web spaces or the forefoot, a transmetatarsal amputation is suitable (see the video below). An osteotomy is performed through each of the metatarsal necks. The plantar surface of each is beveled or rounded to prevent a pressure area from forming.

Typically, a plantar flap is used to close the wound, and regular wound irrigation is recommended. In the presence of infection, the wound is left open to heal secondarily; if no infection is present, it is closed with nonabsorbable sutures.

A concomitant Achilles tendon–lengthening procedure may be required to achieve a neutral position of the shortened foot. The Hoke method of tendon lengthening can be performed as either an open or a closed technique. ^[17]

In a study (N = 147) comparing digital amputation (n = 77) with transmetatarsal amputation (n = 70) in diabetic patients with gangrenous toes, Elsherif et al found that transmetatarsal amputation offered better outcomes, with a lower reintervention rate (15.7% vs 29.9%), a shorter median hospital stay (17 vs 20 d), fewer theater trips, and a longer time without toxicity (346 vs 315 d). ^[18] However, the differences did not reach statistical significance.

Complications of toe amputation include the following:

• Inadequate hemostasis - This may necessitate a return to the operating room for ligation or cauterization of the responsible vessels; pressure bandages may be counterproductive, because they induce ischemia in the area
• Hematoma - Undrained collections of fluid (including blood) are a nidus for infection and should be swiftly addressed
• Proximal gangrene - This is caused by a mismatch between arterial supply and tissue demand and indicates inadequate amputation
• Flap necrosis - This also reflects inadequate blood flow; it is worsened by any tension in the repair, which should be avoided
• Failure to heal - This reflects inadequate blood supply as well; it may also be due to ongoing infection
• Tetanus - This may result from failure to provide tetanus prophylaxis, particularly in trauma-related amputations
• Phantom pain - This is unusual with toe amputations

In a study involving 10 elite alpinists who underwent digit amputation after sustaining freezing cold injury, Gorjanc et al found that amputated toes cooled much faster than their uninjured counterparts and reached lower skin temperatures during the cold exposure test, which suggests that amputated toes might be at greater risk for future freezing cold injury with subsequent cold exposures, as a consequence of less perfusion. ^[19]