Lengthening of a thumb distal phalanx replanted to its metacarpus because of loss of the proximal phalanx: case report

[Application of Ilizarov technique in functional reconstruction of thumb degloving injury after amputation]

Objective

To investigate the effectiveness of Ilizarov technique in reconstruction of thumb function in patients with thumb degloving injury after amputation.

Methods

Between June 2011 and September 2016, 9 cases of thumb degloving injury were treated with amputation and Ilizarov technology. There were 8 males and 1 female with an age of 18-52 years (mean, 34.7 years). The amputation plane was the level of the metacarpophalangeal joint in 5 cases, the level of the proximal metacarpophalangeal joint in 2 cases, and the level of the base of the proximal phalanx in 2 cases (the length of proximal phalanx was less than 1 cm). After amputation, the affected finger was shorter than the healthy finger by 4.0-7.5 cm, with an average of 5.7 cm. On the fifth day after operation, the semi-loop external fixation extender was applied for extension, which was extended by 0.5 mm per day, and was extended once every 6 hours.

Results

After bone lengthening surgery, the first web space elevation and contracture occurred in 8 cases. Six of them were treated with the amputation of the inner muscle of the thumb and the "Z" forming technique, postoperative thumb function recovered well; the remaining 2 cases rejected plasty. All 9 patients were followed up 14-47 months, with an average of 33 months. Bone lengthening time was 64-122 days, with an average of 86 days. The lengthening length of bone was 3.0-5.9 cm, with an average of 4.1 cm, and the average lengthening length was 71.9% of the average shortened length. The fixation time of external fixator was 169-342 days, with an average of 231 days. The healing index was 43.2-59.1 days/cm, with an average of 53.4 days/cm. One case showed prolonged mineralization delay and recovered after "accordion" treatment. Bone healing was finally achieved in all patients, with the healing time ranging from 169 to 342 days, with an average of 231 days. No replantation internal fixation and flexion contracture occurred. The two-point discrimination of extended fingertip was similar to that of normal fingertip. The grip strength reached 53%-89% of the healthy side; the kneading force reached 59%-91% of the healthy side.

Conclusion

The application of Ilizarov technology to extend the thumb metacarpal lengthening is a good method to reconstruction the thumb function after degloving injury.

Secondary procedures in replantation

The success of replantation surgery is not judged by survival of the replanted part, but by the functional outcome attained. Hence, primary repair of all injured structures is the preferred aim. At times, constraints induced by the ischemia time and nature of injury preclude primary repair. In such situations, secondary procedures are inevitable. Secondary procedures are also frequently required to improve the function and appearance of the replanted extremity. The incidence of secondary procedures will vary with the level of replantation and the type of patient population. Secondary procedures are difficult because they carry risk of injury to the vital neurovascular structures that now lay at nonanatomical locations. Nevertheless, when indicated and performed with caution they could significantly raise the functional status of the individuals.

Microsurgery in the urgent and emergent management of the hand

Appropriate use of microsurgical techniques in the emergency management of injured hands increases the salvage rate of complex upper limb injuries. Over time, the indications for replantation, both major and minor, have expanded and techniques refined to get better functional outcomes. The wide choice of free flaps available has made primary reconstruction possible to obtain a good functional and aesthetic outcome. The benefits microsurgery offers in the emergent management of the injured hand are now firmly established. The challenge is to create and maintain centers which can provide around-the-clock, high quality microsurgery services. The issues of adequate training opportunities, obtaining adequate work load to maintain high skill levels, attracting talent into the field are the challenges faced in maintaining high levels of service. In the developing countries, in addition to these issues, increasing the awareness of the potential of microsurgical services among the medical personal and the public has to be addressed.

Alternative method for thumb reconstruction. Combination of 2 techniques: metacarpal lengthening and mini wraparound transfer

Amputation at the proximal phalanx or at the metacarpophalangeal joint can be treated by pollicization of a finger, osteoplastic reconstruction, free microvascular transfer of a toe, or distraction lengthening. The best technique to use to treat these cases depends on the place of amputation and the patient's age, sex, occupation and functional demands. In the past 6 years, we treated 4 patients by lengthening the thumb metacarpal ray and adding a mini wraparound flap from the great toe. All the subjects were female with an average age of 22 years. All 4 patients had sustained traumatic amputations: 2 at the metacarpophalangeal joint and 2 at the base of the proximal phalanx. Distraction was completed approximately 65 days after osteotomy, obtaining an average lengthening of 23 mm. To achieve bone consolidation, the lengthener was left in place for 127 days on average. Microsurgical thumb reconstruction was performed around 3 months after consolidation of the osteotomy. There were no failures or cases of postoperative vascular compromise. The average pinch power was 66% of the opposite hand. The static 2-point discrimination of the reconstructed thumb was 8 mm (range, 7-10 mm). All patients reported being satisfied with the treatment, although 1 patient was partially dissatisfied due to the prolonged length of the treatment. Donor site morbidity was minimal. This procedure is mainly chosen by selected patients who refuse standard microsurgical thumb reconstruction because it requires a longer treatment period.