Thumb reconstruction: Non-microsurgical techniques

Introduction

• When thumb loss occurs due to trauma, replantation is the best method of reconstruction for many patients. When replantation is not possible, thumb reconstruction is warranted.

• The level of thumb amputation guides the type of reconstruction. Determination of the level of loss is based on physical examination and radiographs.

• Any thumb reconstruction method requires input and acceptance by the patient. The reconstruction should be customized to the patient's personal and professional needs. Because significant rehabilitation may be required, the patient must be a willing participant in both the reconstruction and rehabilitation.

• Functional compensation following distal-­third thumb loss is easily achieved; therefore, reconstruction at this level is chiefly soft tissue only. Techniques such as the neurovascular advancement (Moberg) flap and the cross-­finger flap remain reliable methods for reconstruction at this level.

• For losses in the middle third of the thumb, restoration of length is a priority. This can be done via absolute length restoration with metacarpal lengthening or osteoplastic reconstruction, or via relative length restoration using phalangization of the thumb.

• Proximal-­third thumb losses are best treated with microsurgical reconstruction. However, in some cases this may not be possible. In these situations, transfer of another finger can provide an excellent thumb replacement. A normal finger (typically the index) can be pollicized to become a thumb. A damaged index finger can also be transferred (on-­top plasty) to become a stable post for opposition, pinch, and grip.

• Hand rehabilitation after reconstruction is absolutely necessary, especially following middle-­ and proximal-­third reconstructions. Rehabilitation can last months but allows the patient to regain motion and strength. For some procedures, such as neurovascular island flaps and digit transfer, sensory re-­education is an important part of the rehabilitation.

This chapter will provide a comprehensive description of non-­microsurgical thumb reconstruction, including reconstruction decision-­making, technical approaches, and post-­reconstruction management.

Historical perspective

Littler extensively reviewed the history of thumb reconstruction, a field in which he has been a major contributor. Nicoladoni introduced two techniques, namely, osteoplastic reconstruction and toe transfer through the pedicle method. Guermonprez was among the first to pollicize a finger, a technique subsequently refined by the island principle, attributed to Littler and Gosset. A mobile and sensate thumb was obtained, but at the price of sacrificing a finger. Matev originated the technique of progressive lengthening through distraction, maintaining good sensibility and improving length. A major advance was the introduction of microvascular techniques, which led to microvascular free toe-­to-­hand transfer. First-­ and second-­toe transfers were initially described, followed by refined techniques allowing the surgeon to improve the appearance of the reconstructed thumb while at the same time minimizing donor site morbidity.

Basic science/­disease process

By far, the most common “disease process” necessitating thumb reconstruction is traumatic injury. The majority of these patients are working-­age males. Within the larger trauma classification, thumb injury can be the result of a variety of different mechanisms. These include sharp cut, avulsion, and crush. There are some mechanisms that have characteristics of more than one injury type. This phenomenon is best illustrated by saw and lawn mower injuries, which have both cutting and crushing components, resulting in a larger zone of injury.

Other insults that can result in thumb loss requiring reconstruction are infections and neoplasms. Because tumors are not acute events, thumb reconstruction planning can be more deliberate, and, unlike most traumatic situations, reconstruction may be performed at the time of tumor extirpation.

Diagnosis/­patient presentation

The diagnosis of thumb trauma is relatively straightforward, as there will be, in most cases, open wounds. It is important to obtain history regarding the mechanism and other details of the traumatic insult, time from injury to presentation, handedness, occupation, pertinent social issues (such as tobacco use), and pertinent medical problems (including problems that can compromise peripheral circulation and/­or wound healing). If feasible, replantation of the amputated thumb will generally yield a thumb that is superior in appearance and function to any other type of thumb reconstruction. However, this may not be possible, in which case, other reconstruction methods are employed.

Evaluation of the traumatically injured thumb requires complete evaluation of all tissues of the digit including integumentary, neural, vascular, and musculoskeletal. The wound(s) on the thumb should be carefully inspected. The integrity of the sensory nerves supplying the thumb is assessed. Assessment of any compromise in the circulation to the thumb is crucial, as is assessing the feasibility of arterial and venous reconstruction. Finally, assessment of the integrity of the thumb tendons and skeletal structures is performed. Radiographs are necessary to evaluate thumb skeletal structure.

Evaluation of the thumb following infection is similar to that following trauma. All tissues must be assessed, making particular note of the cutaneous defect requiring reconstruction.

Evaluation of a thumb affected by a tumor will be guided by the tumor itself. Specifically, tumor type and grade will guide the extent of extirpation prior to reconstruction. This will also determine which procedures will be needed either intraoperatively (sentinel lymph node biopsy, lymphadenectomy) or perioperatively (radiation, chemotherapy).

Patient selection

Because there are many ways to reconstruct a deficient thumb, patients must be educated about the various options so that they may make an informed decision about the type of reconstruction that will serve them best in both the personal and professional settings ( Video Lecture 13.1 ).

Many thumb injuries occur in the workplace, and these patients will be affected by the injury because their work involves significant hand use. In these patients especially, it is essential to work toward a thumb that has adequate length for both gripping and pinching, is stable during activities, has reasonable motion, and, importantly, is sensate in order to give tactile feedback during these actions and to prevent subsequent injury. That said, adequate length, stability, motion, and sensibility are the end-­goals for any patient requiring thumb reconstruction, regardless of profession or vocation.

In addition to patient input regarding reconstructive methods, the patient must also commit to the reconstructive process. Most of the reconstructive options will result in edema, stiffness, and pain in the near term; therefore, adherence to a supervised hand therapy program is critical to reconstruction success.

As with any type of reconstructive surgery, medical optimization prior to procedure(s) allows superior outcomes. This includes, but is not limited to, tobacco cessation, cardiopulmonary stabilization, and diabetes control. If the thumb is being reconstructed following cancer extirpation, the physician must ensure adequate local disease control prior to reconstruction, and coordination of the patient's reconstruction with any systemic adjuvant therapies that will be required. Similarly, in patients for whom a thumb is deficient due to infection, infection control prior to reconstruction is paramount.

The most important factor in patient selection is the amount and nature of tissue loss that must be reconstructed. The level of amputation is the easiest way to classify thumb deficiencies and is listed in thirds ( Fig. 13.1 ). The distal third extends from the interphalangeal joint to the thumb tip. The middle third is the portion between interphalangeal joint and the metacarpal neck, and the proximal third is from metacarpal neck to the carpometacarpal joint. Each amputation level presents unique challenges for patient and physician, and each level can be reconstructed with multiple modalities.