Preprocedural Planning
The primary initial goal in the treatment of traumatic amputations is to evaluate the suitability of the amputated part for replantation. Amputations of the thumb, multiple fingers, the hand at the level of the wrist or distal forearm, and the upper extremity above the elbow should be evaluated for replantation because patients can benefit from replantation of these appendages even if the resulting function of the part is less than optimal. [16, 17] Patients with mangled digits may also benefit from amputation instead of reconstruction.
Although replantation at these levels can often achieve good functional outcomes, replanted single fingers may be stiff and impede the opposition of other fingers to the thumb, as well as overall hand function. Replanted single-finger amputations can achieve a better range of motion (ROM) when the level is distal to the insertion of the flexor digitorum superficialis (FDS). [15] Complete digital amputations undergoing replantation surgery have a higher failure rate than incomplete digital amputations. [18]
Single-finger replantation can be considered when patients have injuries to other fingers of the same hand. All of these injuries require splint immobilization and rehabilitation that impede immediate return to work. Accordingly, single-finger replantation can be considered in special circumstances. The surgeon must not become absorbed in the technical challenge of the replantation to the point where the other associated injuries are neglected, because poorer outcomes and greater financial cost (due to lost wages and the cost of hospitalization and therapy) can result. [19]
In performing an amputation, it is important to preserve functional length. For example, an above-elbow arm amputation should be replanted to provide the patient with a functional elbow on which a prosthesis can be fitted, resulting in better function than an above-elbow prosthesis. Durable coverage at the end of an amputation is critical to the function of an amputation. This may necessitate the use of a local flap. Preservation of sensibility on the amputation stump can optimize the usefulness of the remaining appendage.
Sometimes, local flaps can be used to bring sensate tissue to the stump tip. It is important to minimize the risk of painful neuroma formation at the amputation stump and to prevent joint contractures. Some local flaps can pose a risk of joint contracture to the involved finger and adjacent fingers. Use of the delayed groin flap can risk elbow and shoulder joint contractures.
Other critical objectives in the treatment of amputations are early return to work and fitting with a prosthesis, when possible.
Imaging Studies
Often, plain radiographic studies may be helpful to determine the most suitable level of amputation for traumatic crushing injuries. If the amputation is being performed for a tumor, other radiographic studies (eg, magnetic resonance imaging [MRI]) may be useful for determining the proximal extent of a tumor.
-
In performing an index ray amputation, a dorsal longitudinal incision over the index metacarpal is used in conjunction with a circumferential skin incision at the midproximal phalangeal level. The skin is intentionally left long distally to avoid deficiency, which could result in a web-space contracture.
-
The principles of a central ray amputation include removal of the injured finger at the metacarpal base, correcting the rotational deformity, closing the space between the 2 adjacent unamputated fingers, and achieving a satisfactory appearance of the hand.This illustration depicts 1 of 2 techniques that have been described regarding central ray amputation. The procedure involves the transfer of the index finger ray onto the third metacarpal base for the middle finger and the small finger to the ring metacarpal base. The disadvantages of the ray transfer procedure are the requirement for postoperative immobilization and the risk of nonunion.
-
The second central ray amputation technique involves removing the involved finger at the metacarpal base. The disadvantages of this technique are eventual widening of the web space and rotational deformity of the digit. The risk of these complications can be minimized by repairing the deep transverse intermetacarpal ligament and using a threaded Kirschner wire (K-wire) to secure the second to the fourth metacarpal.
-
The technique of central ray amputation involves the use of a circumferential incision at the midproximal phalanx in conjunction with a dorsal longitudinal incision. The dorsal incision is extended through the extensor. The periosteum is scored at the level of the metacarpal base.
-
In performing a central ray amputation, the dorsal incision is performed in a tennis racket configuration.
-
The volar incision is completed in the shape of a wedge to facilitate closure without a dog ear.
-
The dorsal incision is extended through the extensor. The periosteum is scored at the level of the metacarpal base.
-
With a central ray amputation, the metacarpal is transected at its base. The hand is then supinated and the flexor is divided.
-
The flexor tendon is divided and allowed to retract proximally.
-
The metacarpal base is transected with a sagittal saw.
-
The amputated central ray is shown here.
-
The proper digital nerves and arteries to the adjacent fingers are preserved from the common digital neurovascular bundles.
-
The neurovascular bundles are divided proximally to avoid neuroma formation at the skin incision.
-
The deep transverse metacarpal ligaments are identified on either side of the volar plate of the involved finger at the metacarpophalangeal joint. In transecting the deep transverse metacarpal ligaments, it is essential to preserve enough ligament to attach to each other to minimize gap formation and rotational deformity.
-
The deep transverse metacarpal ligaments are repaired with 2-0 Ethibond nonabsorbable sutures.
-
The gap is compressed, and transverse Kirschner wires (K-wires) are placed through the metacarpals on either side of the ray amputation. Threaded K-wires can help resist the sliding of the metacarpals on the K-wires like an accordion.
-
The threaded Kirschner wire can help to prevent rotational deformity.
-
Active motion is begun early, and the Kirschner wires can be removed at 6 weeks. This technique can be applied to ray amputation of both the middle and ring fingers.
-
In performing a central ray amputation of the ring finger, the deep transverse intermetacarpal ligament can be repaired to avoid the need for metacarpal transfer.
-
The procedure of small finger ray amputation is performed through a tennis racquet incision.
-
When the thumb tip has been amputated, replantation can provide the patient with the best return to function even if interphalangeal joint fusion is required.In the event that replantation cannot be performed or is unsuccessful, minimal bone shortening should be performed to provide a smooth bone end over which to close the skin. In fact, the bone should not be removed only to obtain primary skin closure. A volar rectangular advancement flap (Moberg) should be used to provide soft-tissue closure and preserve thumb length.
-
The volar advancement flap is raised as a rectangle to include both neurovascular bundles to the metacarpophalangeal crease of the thumb and is advanced in the distal direction.
-
The Moberg flap can be used to close 1- to 1.5-cm defects. If the amputation level is at or distal to the distal interphalangeal joint, the patient should not experience much functional loss.
-
The Moberg flap can allow for length preservation and coverage of the thumb tip with sensate skin because it contains both neurovascular bundles.
-
If the patient's amputation level is proximal to the interphalangeal joint, reconstruction with toe transfer should be considered. If the amputation is at the carpometacarpal level, pollicization can be considered.
-
This patient had a digital nerve neuroma (outlined in marker) following revision amputation. He had point tenderness over the neuroma. The skin and neuroma were removed.
-
The neuroma is dissected, and a traction neurectomy is performed.
