Digital Amputations Technique

Updated: Nov 02, 2015
  • Author: Bradon J Wilhelmi, MD; Chief Editor: Harris Gellman, MD  more...
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Technique

Digital Amputations

In performing digital amputations, provide a mobile, stable, painless stump with the least interference from the remaining tendon and joint function to provide the most useful amputation stump. The remaining viable skin is conserved because it may be needed to provide durable soft-tissue coverage for the amputation stump. When possible, use volar skin for the stump coverage because it provides skin that is thicker and more sensate than dorsal skin. [7]

There are several local options for tissue rearrangement of volar skin over the amputation stump, including the following [8, 9] :

  • Fillet flaps
  • Volar V-Y flaps
  • Bilateral V-Y flaps
  • Homodigital island flaps

"Dog ears" in the acute traumatic amputation often should be left to eliminate tension and to prevent compromising the blood flow to the remaining flaps achieving closure; these dog ears disappear over time. If the wound is small, it can be allowed to heal spontaneously by contraction and epithelialization. Wounds smaller than 1 cm can heal spontaneously in a reasonable amount of time. Larger wounds may require a skin graft to heal quicker. [10] Split-thickness grafts can be used for the benefit of wound contraction to result in a smaller area on the tip, which is not normal pulp. [11]

Regarding the treatment of the bone in a digital amputation, the bone under the stump end must be smooth. Remaining bone chips and devitalized bone should be removed. The bone at the stump end can be smoothed by using a rongeur and file. Bone length is not as important as a stump with mobile nonsensitive coverage. The bone of the distal phalanx must be of adequate length to support the nail bed and nail growth. [12, 13, 14, 15] With digital amputations involving the thumb, length is important.

The articular cartilage can be preserved when the amputation occurs at the level of the interphalangeal (IP) joint. This articular cartilage can provide a shock pad for trauma and potentially causes less pain under than skin than the bone edges. Whitaker et al clinically evaluated the preservation of the articular cartilage with digital amputations and found a better outcome when the cartilage was left on the stump end. [16] The protruding condyles and anterior aspect of the phalanx may be trimmed to provide a less bulbous stump.

In addressing the nerve at the stump end, it is important to avoid neuroma formation in this location. The nerve end should be in a position away from the stump end or an anticipated point-of-contact pressure. To minimize the risk of neuroma formation at the stump end, traction neurectomy of the digital nerve should be performed bilaterally for each digital amputation. The nerve is longitudinally distracted in the distal direction and then transected to allow proximal retraction, leaving the nerve end 1-1.5 cm from the fingertip.

Preservation of a tendon insertion improves the active mobility and function of an amputation stump. Therefore, when possible, tendon insertions should be preserved. However, the amputation level is often proximal to the tendon insertion. The flexor digitorum profundus (FDP) tendon should never be sutured over the bone end or to the extensor, because this can result in the quadriga effect. This effect reduces excursion of the adjacent normal fingers because of the common profundus muscle from which all the profundus tendons originate. The amputated finger, which has a tighter profundus tendon, reaches the palm before the other fingers do and results in a weaker grip.

Another complication of tendon imbalance is the lumbrical plus posture, which is the paradoxical extension of the involved finger's proximal interphalangeal (PIP) joint with attempted flexion. This occurs when the profundus tendon is allowed to retract proximally, resulting in a pull on the lumbrical muscle as it originates from the profundus.

The lumbricals contribute to metacarpophalangeal (MCP) joint flexion and IP joint extension. This proximal pulling of the profundus pulls the lumbrical tighter to extend the IP joints paradoxically with attempted flexion. [17] However, lumbrical plus posture after amputations of the distal interphalangeal (DIP) joint is rare. Also, adhesions can result; therefore, early motion of the amputated finger is recommended.

The digital arteries should be identified and ligated with small-caliber sutures or should be cauterized. The visible veins can be cauterized as well. Then, the skin is loosely approximated to make sure there is no tension on the skin edges. If there is tension on the skin, the bone may be shortened or local flaps can be used.

When amputations are at the level of the distal phalanx, preservation of the profundus insertion is critical. An intact profundus improves functional contribution of the amputated finger and improves grip strength by providing active flexion at the DIP joints in conjunction with the other fingers. Preservation of enough bone to support normal nail growth is perhaps the most crucial predictor of functional length with amputations at this level.

Amputations at the level of the DIP joint can be closed over the articular surface of the middle phalanx. Local flaps can be used to provide soft tissue for closure over the middle phalanx, if needed. The volar V-Y flap is the standard local flap option for injuries at this level. The volar V-Y flap is fashioned with the apex of the V at the PIP crease. When amputations are through the middle phalanx, preserving the flexor digitorum superficialis (FDS) insertion, which inserts on the middle third of the middle phalanx, is desirable. Amputations proximal to the FDS insertion leave the amputated finger without active motion control at the PIP joint level and only with active motion at the MCP joint level.

Amputations at the PIP joint can be closed over the articular surface of the proximal phalanx, as can those at the DIP. Amputations at this level can still actively flex at the MCP joint through the action of the intrinsic muscles. If the amputation is near the MCP joint, especially in the long and ring fingers, dropping small objects because of the defect can be addressed with a finger prosthesis or ray amputation, with or without transposition.

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Ray Amputations

Index finger ray amputations

The index finger is the most important digit other than the thumb; it is the primary finger used with the pinch function. If length, sensation, and mobility of the index finger are inadequate, the patient bypasses the index finger to preferentially use the middle finger for pinch functions. In this circumstance, an index stump can impede the function of the middle finger and the overall function of the hand. This is the primary indication for a ray amputation of the index finger.

The level of amputation that makes the index finger a candidate for a ray amputation is controversial. A ray amputation of the index finger should not be performed acutely for injuries distal to the MCP joint unless the spare parts are needed for salvage of other digits, such as the thumb. The remaining index finger may be left during a trial period after the initial injury. If the stump impedes function, it can be electively converted to a ray amputation. However, conversion to a ray amputation can narrow the palm and result in a loss of grip strength and pronation strength, justifying a trial with the shorter index finger for laborers.

Murray et al found that power grip, key pinch, and supination strength are diminished by approximately 20% of normal with index ray amputations. [18] Pronation strength is diminished by 50% in the same group of patients. The cosmetic appearance of an index ray amputation is highly acceptable.

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 that could result in a web-space contracture. (See the image below.)

In performing an index ray amputation, a dorsal lo 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 dorsal veins are ligated, and the extensor tendons are transected. The periosteum is scored, and the metacarpal base is transected. The dorsal interosseous and lumbrical muscle tendons are transected. Studies have shown no difference in pinch strength with dorsal interosseous transfer to the second dorsal interosseous muscle; therefore, this technique is not indicated. [18] Then, the flexor tendons are divided. The digital arteries and nerves are divided distal to the branches to the palmar skin.

Interrupted sutures are used for skin closure. The hand is dressed lightly to allow for early motion.

Middle and ring finger (central) ray amputations

When the middle and ring fingers are amputated at a level near the MCP level, small objects fall through this area, which is created by the gap of the missing digit. Patients describe difficulty in retrieving change from their pockets. This can be corrected with a ray amputation. However, the loss in grip strength and pronation strength has to be considered before ray amputations are performed for these central digits.

The principles of a central ray amputation include the following:

  • Removal of the injured finger at the metacarpal base
  • Correcting the rotational deformity
  • Closing the space between the two adjacent unamputated fingers
  • Achieving a satisfactory appearance of the hand

Two techniques of central ray amputation have been described. One involves the transfer of the index finger ray onto the third metacarpal base for the middle finger, and the small finger is transferred to the ring metacarpal base (see the first image below). The other involves removing the involved finger at the metacarpal base (see the second image below). The disadvantages of the ray transfer procedure are the requirement for postoperative immobilization and the risk of nonunion. Therefore, the authors' preferred technique for central ray amputation does not involve ray transfer.

The principles of a central ray amputation include 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 involv 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 (see the images below). The dorsal incision is extended through the extensor. The periosteum is scored at the level of the metacarpal base. The metacarpal is transected at its base. Then, the hand is supinated, and the flexor is divided. 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 MCP joint.

The technique of central ray amputation involves t 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 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 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 extens 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 t 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 retrac The flexor tendon is divided and allowed to retract proximally.
The metacarpal base is transected with a sagittal The metacarpal base is transected with a sagittal saw.
The amputated central ray is shown here. The amputated central ray is shown here.
The proper digital nerves and arteries to the adja The proper digital nerves and arteries to the adjacent fingers are preserved from the common digital neurovascular bundles.
The neurovascular bundles are divided proximally t The neurovascular bundles are divided proximally to avoid neuroma formation at the skin incision.
The deep transverse metacarpal ligaments are ident 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 repai The deep transverse metacarpal ligaments are repaired with 2-0 Ethibond nonabsorbable sutures.
The gap is compressed, and transverse Kirschner wi 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 ro The threaded Kirschner wire can help to prevent rotational deformity.
Active motion is begun early, and the Kirschner wi 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 transecting the deep transverse metacarpal ligaments, it is essential to preserve enough for attaching the ligaments to each other so as to minimize gap formation and rotational deformity. Then, the ray is amputated. 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. Then, the deep transverse metacarpal ligaments are repaired with 2-0 Ethibond nonabsorbable sutures. The threaded K-wire can help prevent rotational deformity. Active motion is begun early, and the K-wires can be removed at 6 weeks.

This technique can be applied to ray amputation of both the middle and the ring fingers (see the image below). Incomplete closure of the defect and scissoring must be carefully avoided with this technique.

In performing a central ray amputation of the ring 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.

Small finger ray amputations

The small finger plays a role in gripping and hooking objects. Small finger injuries are the most difficult to rehabilitate, and the finger often becomes stiff and immobile, possibly hindering hand function by catching on pockets or other objects. In this circumstance, small finger amputation can be considered. In a laborer, the amputation can be performed at the MCP joint to remove the flail segment of the proximal phalanx but preserve a broad palm.

If grip strength is not a concern, a more esthetic appearance can be obtained with a small finger ray amputation. In performing a small finger ray amputation, it is important to preserve the insertion of the extensor carpi ulnaris, which inserts on the base of the fifth metacarpal. [19] This procedure is performed through a tennis-racquet incision (see the image below). Moreover, the hypothenar muscles are preserved to cover the gap and provide padding to the ulnar side of the hand. [1]

The procedure of small finger ray amputation is pe The procedure of small finger ray amputation is performed through a tennis racquet incision.
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Thumb Amputations

The most critical digit to hand function is the thumb. Amputations of the thumb can be debilitating. The level of amputation determines the significance of the functional deficit. In general, the thumb is important as a post to which the fingers oppose. Therefore, in contradistinction to the length of the fingers, the length of the thumb is more important than active motion.

When the thumb tip has been amputated, replantation can provide the patient with the best return to function, even if IP 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, as seen in the images below. The volar advancement flap is raised as a rectangle to include both neurovascular bundles to the MCP crease of the thumb proximally, and then it is advanced in the distal direction.

When the thumb tip has been amputated, replantatio 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 rectangl 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 (see the first and second images below). If the amputation level is at or distal to the IP joint, the patient should not experience much functional loss. If the patient's amputation level is proximal to the IP joint, reconstruction with toe transfer or metacarpal lengthening and web-space deepening should be considered (see the third image below). If the amputation is at the carpometacarpal (CMC) level, pollicization can be considered if the index finger is not injured.

The Moberg flap can be used to close 1- to 1.5-cm 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 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 t 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.
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Other Amputations

Transcarpal amputations

Transcarpal amputations are rare. Usually, amputations at this level can be replanted and an acceptable return of function is expected. When replantation is unsuccessful or cannot be performed, minimal reconstructive options exist for amputations through the carpus. In general, patients can be fitted with hand prostheses, which provide good cosmetic results. When the wrist supplies active motion, the prosthesis can be operated without an attachment to the elbow or shoulder harness.

Wrist disarticulations

Again, amputations at this level are rare and can often be replanted. Historically, amputations at the below-the-elbow level have been favored over wrist disarticulations because of the difficulty in wrist prostheses. However, with advances in technology, amputations at this level can be considered. Also, the wrist disarticulation level is preferable in children compared with disarticulation below the elbow to preserve growth potential.

The advantage of preserving the distal radioulnar joint is that full, active pronation and supination can improve the function of the amputated appendage. Therefore, when possible, the distal radioulnar joint should be preserved. Also, the radial styloid flare should be preserved to improve prosthetic suspension. If possible, the palmar skin should be used to cover the stump end to provide a thicker and more durable coverage.

Below-elbow amputations

In general, below-the-elbow amputations should be performed to preserve as much length as possible and thereby preserve maximal pronation and supination. When traumatic amputations are more proximal, even 2 cm of ulnar bone length is sufficient to fit a below-the-elbow prosthesis. With more proximal amputations, the biceps can be reattached to the ulna at a position that approximates the normal resting length of the muscle. If the biceps is reattached under too much tension, a flexion contracture can result. A soft-tissue deficit may necessitate the use of a free flap or local flap to preserve the elbow. [20]

Krukenberg procedure

The Krukenberg procedure is mentioned mainly for historical purposes. This operation was first described by Krukenberg in 1917 and involves separating the ulna and radius for below-the-elbow amputations to provide a pincerlike grasp that is motored by the pronator teres. The indication for this operation is reserved for a blind person who is undergoing bilateral amputation because it can provide prehension and tactile gnosis.

Elbow disarticulations

Elbow disarticulations are preferred by surgeons and prosthetists to above-the-elbow amputations because they allow for rotary force transmission over the humerus and because the epicondyles provide good support for the prosthesis. The disadvantage of an amputation at this level is that the prosthesis has outside locking hinges, which can damage clothing.

Above-elbow amputations

In traumatic above-the-elbow amputations, bone resection should be avoided, because maintenance of the stump length is critical to function. The longer humeral stump has better proximal muscular control and provides a long lever to help maneuver the prosthesis. Even if required for primary closure, bone shortening should be avoided. Split-thickness skin grafting can be considered over the stump end to preserve the stump length. It is essential to have bone below the insertion of the pectoralis major. Amputations that are more proximal to the pectoralis are essentially shoulder disarticulations because shoulder motion is lost.

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Complications

Complications in the amputated stump related to the bone include formation of osteophytes and osteomyelitis. The risk for these bony complications can be minimized with appropriate bony debridement at the initial treatment.

Early postoperative complications include wound hematoma, infection, and necrosis. Hemostatic control of the amputation stump can be achieved initially with a tourniquet. Thoroughly irrigate and debride the amputation wounds to minimize the risk of postoperative infection. Devitalized skin, tendon, and muscle should be removed to minimize the risk of infection as well.

Postoperatively, patients can experience symptoms of pain in the amputated part or stump. Phantom limb is the sensation of feeling in the amputated part, and it is common after amputations. Patients should be informed of this potential complication preoperatively. The likelihood of developing phantom limb pain is highest after severely mutilating amputations, and it usually begins soon after the amputation. When made aware of this potential symptom preoperatively, patients seem to tolerate the sensation better.

Stump pain is usually a result of a neuroma forming at the stump site. Sometimes, these neuromas have to be excised and buried into muscle or bone to minimize the local pain (see the images below). Interdigital direct neurorrhaphy has been described as an option for treating painful neuromas developing after finger amputation. [21]

This patient had a digital nerve neuroma (outlined 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 neurectom The neuroma is dissected, and a traction neurectomy is performed.

Patients can have cold intolerance and hypersensitivity at the stump end. [22] Usually, this is a self-limited process. Desensitization may hasten the resolution of these symptoms, and a transcutaneous electrical nerve stimulation (TENS) unit may be helpful. Gabapentin may also be effective.

Contracture prevention is critical in the treatment of amputations. Local flap options for soft-tissue reconstruction often involve immobilization during a delay, which can result in contracture formation of an adjacent digit as with crossfinger or thenar flaps or of the shoulder, elbow, and wrist with the groin flap. It is imperative to begin early motion of the amputated part to minimize the risk of contracture formation.

Finger tendon imbalance after finger amputations can result in a weakened grasp. When the FDP is sutured over the stump end, the patient can develop a quadriga, which can result in the amputated finger beating the others to the palm because of the shorter tendon, thus limiting the range of motion of the uninjured adjacent fingers. When the FDP tendon is allowed to retract proximally, this can result in the lumbrical plus posture (ie, the paradoxical hyperextension of the IP joints with flexion). The lumbrical plus posture can be treated by releasing the lumbrical or radial lateral band.

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