CHAPTER 73 EXTREMITY REPLANTATION: INDICATIONS AND TIMING

The years since the first successful replantation of an arm in a 12-year-old boy by Malt and McKhann¹ in 1964 were marked by evident progress in the reconstructive surgery of limbs. That first revolutionary report was followed by the reports of revascularization of incompletely amputated fingers by Kleinert and colleagues in 1965² and the first successful thumb replantation by Komatsu and Tamai in 1968.^3,4 The evolution of microsurgical techniques and an accumulation of experience worldwide, along with the organization of specialized centers, has made replantation of completely or partially amputated extremities a generally accepted treatment of choice.

CLASSIFICATION

All traumatic amputations of extremities are classified based on:

Type of amputation

Level of amputation

Mechanism and character of injury

This approach to classification serves both academic and clinical purposes and presents a foundation upon which the indications for replantation are predicated and functional outcomes assessed and compared.

Types of amputations are classified by anatomic criteria. The complete type is clearly defined by its term, that is, an amputation without any tissue connection between amputated and proximal parts of the extremity. An incomplete, or partial amputation is where most of vital anatomic structures are disrupted, and blood circulation in the amputated part of the extremity is absent; without replantation the amputated segment will neither survive nor be functional (Figure 1).

Figure 1 (A) Incomplete traumatic amputation of the hand at the level of carpus. (B, C) Functional result of replantation 1 year after replantation: (B) flexion; (C) extension.

The level of traumatic amputation of the extremities is defined by the level of the skeletal rather than soft-tissue disruption. Based on these criteria, we divide all traumatic amputations (replantations) of the extremities into two main groups: major and minor amputations (replantations).

The necessity of differentiating the extremity amputations and replantations has been stressed by many authors for important clinical reasons, especially for indications and timing of surgery. This is due to the fact that major segments of the extremities contain large muscle mass, and anoxia of the muscles largely determines successful outcome of, and therefore indications for, replantation.

Minor segments are those amputated distal to the wrist or ankle level, and major segments are those amputated at and proximal to the level of the respective joints.

More precise classification of upper extremity amputations and replantations is based on the “zonal” principle, where the upper extremity is divided into six anatomic zones (Figure 2):

Zone I—distal to the insertion of the flexor digitorum superficialis (FDS) tendons

Zone II—at the level of the fibro-osseous canals of the flexor tendons, between anterior interosseous (AI) pulley and FDS tendon insertion

Zone III—the palm itself, between Zones II and IV

Zone IV—the level of carpal tunnel

Zone V—from the wrist to the musculotendinous junction

Zone VI—proximal to the musculotendinous junction

Figure 2 Flexor zones of the hand.

Based on the mechanism of trauma, we differentiate the following types of injury and various combinations of these in the same patient:

Guillotine: a very sharp wound with minimal skin and soft-tissue damage

Cutting: for instance, a guillotine with some zone of contusion

Crushing: the skin and soft-tissue injury zone is significant, often associated with comminuted fractures

Avulsion: dissociation in levels of amputation of bone and soft tissues, almost always requiring vessel grafts (Figure 3)

Figure 3 (A) Avulsion amputation of the ring finger. Note skeletal amputation at the level of distal interphalangeal joint, whereas soft tissues, vessels and nerves are avulsed from the base of the finger. (B, C) Functional result 6 months after replantation: (B) flexion; (C) extension.

Patients with traumatic amputation of an extremity and associated significant injury to other organs, such as the head, chest or abdomen, usually represent a special challenge. These combined injuries are usually life-threatening and often preclude replantation.

INDICATIONS

We define replantation as a restorative surgery for the reestablishment of the anatomic integrity of major structures of an extremity in complete or partial amputation in order to regain the viability of the extremity and attain the acceptable functional outcome.

It appears from the review of the literature and our own experience that the indications for replantation have changed over the years.⁵ Increasing experience has brought a clear understanding that, in evaluating the results of replantation, the only common denominator is functional outcome. We agree with Pederson that the indications for replantation should not be “based solely on potential viability but are predicated on the potential for long-term function.”⁶

When considering replantation, one should take into account the status of the amputated part and the patient’s general condition. In general, while any patient with complete or partial amputation can be considered as a candidate for replantation, an ideal candidate should have had not only a relatively benign local status, e.g., an amputation with minimal contamination and/or contusion but also, and maybe more importantly, a real determination for the continuous hard work later to attain and maintain the function of the replanted extremity or its part.

Assuming technical feasibility, the indications for replantation in traumatic amputations follow:

The thumb provides 40%–50% of the hand’s function. Usually replantation offers the best functional result as compared with other reconstructive options, including toe-to-hand transfer (Figure 4). Even with decreased motion and sensation, the replanted thumb provides such critical tasks of the hand as pinching and grasping. Therefore, all efforts should be made to replant the amputated thumb, unless the functional outcome is dismal.

Multiple digital amputations always present a reconstructive puzzle. In general, all feasible replantations should be performed, aiming at the best possible functional result. If not all digits are replantable, the least damaged finger is usually replanted to the most functionally favorable position (heterotopic or transpositional).

Amputations of a single digit in zone I—despite the recent conservative trend in replantations at the level distal to the flexor superficialis tendon insertion (e.g., Zone I), these usually have favorable functional outcome.

All transmetacarpal amputations, or zone III, regardless of the thumb involvement—an absolute indication for replantation.

Hand amputations at the level of the wrist and above, up to mid-humerus level—the risk of general complications increases with increasing anoxia time and muscle mass.

Any amputation in a child where replantation is technically feasible.

Figure 4 (A) Complete traumatic amputation of the thumb at the level of proximal phalanx. (B, C) Functional result 7 months after replantation: (B) flexion; (C) pinch.

General considerations, such as age, gender, occupation, and even a hobby, should be carefully considered every time replantation is contemplated. We recognize that any amputation in a selected group of patients with an extremely demanding occupation, such as musician or calligrapher, or with cosmetic demands in female patients, can be an indication for replantation.

Contraindications to replantation follow:

Relative

Single digit in zone II (from AI pulley to FDS insertion)

Prolonged warm ischemia

Atherosclerotic vessels

Mentally unstable patients

Absolute

Multiple-level amputations

Patients with severe combined trauma or systemic illness

Significantly crushed or avulsed amputated part