Abstract
When the index finger is injured or severed with a traumatic thumb amputation, transfer of the injured index finger can restore the function of the thumb. The purpose of this study was to evaluate the result of the transfer of an injured index finger for the traumatic loss of the thumb. A patient had a traumatic amputation at the first metacarpal level with the bone defect of the second metacarpal and proximal part of index finger. She was treated with a pedicled transfer of the injured index finger to the ipsilateral thumb. Postoperative evaluations included thumb range of motion, opposition and pinch function, grasp and pinch strength, sensation, and a patient-rated appearance of the thumb and hand. In result, the blood supply of the transferred traumatic index fingers was normal, and the transferred index fingers survived without complications. The range of motion of the first metacarpophalangeal joint and interphalangeal joint was almost the same as that of a normal thumb. The opposition and pinch function of the thumb was also normal. The patient is able to complete activities of daily living with the new thumb. Nevertheless, the sensation has not yet been completely restored. In conclusion, it is feasible to treat traumatic thumb amputation with the transfer of injured index finger.
Introduction
The thumb accounts for 40–50% of total hand function, and amputation of the thumb decreases roughly half of hand function. 1 Therefore, patients have a strong demand for the reconstruction of the damaged thumb. Special considerations for thumb reconstruction include the need to restore sufficient length for opposition, proper position in abducted pronation relative to the other digits, stability as well as mobility of the reconstructed thumb, adequate motor strength for pinch and grasp, and finally sensitivity. 2 A variety of techniques have been developed to reconstruct the thumb, including pollicization of a finger, osteoplastic reconstruction, web space deepening, and free transfer of a toe. 3 The optimal technique depends on the level of amputation, damage to adjacent digits and soft tissues, and the surgical expertise available. Pollicization of the index finger as the reconstructed thumb has been performed for many years, and the use of traumatized index finger stumps for thumb reconstruction has also been described in some reports. 3 –5 We performed pollicization with an injured index finger and anterolateral thigh flap transfer for thumb reconstruction.
Materials and methods
This is a retrospective study, based on medical records from the archives of the Shanghai Fengxian Central Hospital. This clinical study was approved by Shanghai Fengxian Central Hospital Medical Ethical Committee, and informed consent was obtained from the patient for surgical procedures and inclusion of data in studies.
A 64-year-old female patient sustained a severe crush injury. Her left thumb and most of the first metacarpal bone were lost. The first dorsal and volar interosseous muscles and the thenar muscles were lost; part of the second metacarpal bone and the proximal phalanx were also lost. Both the radial and ulnar digital neurovascular bundle to the index finger was left intact. There were volar and palm skin defects of the hand. The patient had no medical history of hypertension, diabetes, or heart disease.
Range of motion of the reconstructed thumb interphalangeal and metacarpophalangeal joints, grip and pinch strength, two-point discrimination of the thumb, Disabilities of the Arm, Shoulder, and Head (DASH) score, and complications were recorded. Her satisfaction and the appearance of the reconstructed thumb were also recorded. The patient was also asked if her hand function improved, worsened, or stayed the same after surgery.
Surgical technique
One-stage operation
Under brachial plexus anesthesia, the wound was rinsed and disinfected, the free bone fragments were removed, and the devitalized soft tissue was debrided. Two Kirschner wires were used to fix the remnant part of the second metacarpal and the proximal phalanx of the index finger. Then, the wound was covered and subjected to vacuum sealing drainage (VSD) for 10 days (Figure 1).
(a) The loss of the thumb and thenar muscles of her left hand can been seen from the palm. (b) The loss of the thumb, first metacarpal, second metacarpal, and thenar muscles can be seen from the back of the hand; (c) The X-ray anteroposterior film of the left hand. (d) The X-ray lateral film of the left hand. (e) Two Kirschner wires were used to fix the remnant part of the second metacarpal and the proximal phalanx of the index.
Two-stage operation
After 10 days, the survival of index finger and adjacent soft tissue was ensured. Under general anesthesia, index pollicization and anterolateral thigh flap for thumb reconstruction were performed. The devitalized tissue was debrided, and the wound was rinsed. The neurovascular bundles of the index finger were identified and dissected appropriately. The broken part of the proximal phalanx of the index finger was removed, and the finger was rotated approximately 90° so that it assumed a position enabling end-to-side pinch with the tip of the adjacent middle finger. Two Kirschner wires were used to fix the base of the first metacarpal to the transferred proximal phalanx of the index. We did not find the extensor pollicis longus tendon; therefore, we chose to anastomose the extensor digitorum tendon of the transferred index to the indicis extensor longus tendon and adjust it to a proper tension. The flexor digitorum profundus tendon of the transferred index was cut and sutured with the flexor pollicis longus tendon, and we adjusted it to the proper tension (Figure 2). Soft tissue cover was provided by a free anterolateral thigh flap simultaneously. The flap was slightly larger than the recipient. The proximal end of the lateral circumflex femoral artery was anastomosed to the radial artery, the venous concomitants were anastomosed to two branches of the cephalic vein, and the nerves were anastomosed to the superficial branch of the radial nerve. After anastomosis, the blood supply and venous return of the flap and the reconstructed thumb was adequate (Figure 3). Postoperative plaster external fixation was performed.
(a) The neurovascular bundles of the index were carefully dissected. (b) Two Kirschner wires were used to fix the base of the first metacarpal to the transferred proximal phalanx of the index finger. (c) The blood supply of the transferred index finger was good. (d) The transferred index finger had sufficient length to do the pinch motion with the middle figure. (e) The extensor digitorum tendon of the transferred index finger was anastomosed to the indicis extensor longus tendon. (f) The flexor pollicis longus tendon was found near the carpal joint. (g) The flexor digitorum profundus tendon of the transferred index finger was anastomosed to the flexor pollicis longus tendon.
(a) The area of the anterolateral flap. (b) Dissection of free flap from the left thigh. (c) Suture of the donor site. (d) Anastomosing the lateral femoral artery with the radial artery. (e) Anastomosing the venous concomitants with the cephalic vein. (f) Anastomosing the nervus cutaneous to the superficial branch of the radial nerve. (g) Blood supplies to the reconstructed thumb were adequate during the operation. (h) Blood supplies to the transferred flap were adequate during the operation.
The plaster external fixation was removed 2 weeks after the surgery, and the kirschner wires were removed 8 weeks after the surgery.
Results
The patient was discharged 7 days after the second-stage surgery. The follow-up period was 1 year. Postoperative X-ray examination revealed good lateral alignment of the fracture ends. The blood supplies to the transferred thumb and flap were normal. The opening of the thenar muscle was 8 mm, slightly smaller than the healthy thumb. The functions of the metacarpophalangeal and interphalangeal joints were almost equal to that of the normal thumb. The DASH score was 38, according to the DASH questionnaire. 6 Sensibility had not yet recovered completely, the two-point discrimination was 6 mm (3 mm in the contralateral thumb), but the conversion of position sense was completed. She could perform pinch and grip activity using her left hand. She was very satisfied with the cosmetic and functional results (Figure 4).
(a) The blood supply of the reconstructed thumb was good after 1 week of operation. (b) The transferred flap survived after 1 week of operation. (C) The reconstructed thumb could flex after 1 week of operation. (d) The postoperative X-ray oblique film revealed good lateral alignment of the fracture ends. (e) The reconstructed thumb survived 4 weeks after surgery. (f) The transferred flap survived 4 weeks after surgery. (g) The reconstructed thumb could flex and extend 4 weeks after surgery. (h) The postoperative X-ray oblique film revealed fracture healing 4 weeks after surgery.
Discussion
Crush injuries of the hand are devastating and usually involve multiple structures of the fingers and hand. These injuries often lead to significant disability. Reconstruction of injured thumbs has been important to the recovery of hand function. Thumb reconstruction depends on the location and type of injury to the thumb and other involved digits and the patients’ own demand. Free transfer of the second toe has been a routine procedure for the reconstruction of the thumb defect; nevertheless, the appearance and function of reconstructed thumb is often inadequate, therefore many patients do not accept this surgical procedure. 1 Index finger pollicization not only has high survival rate but also preserves good sensation, appearance, and function. Although this procedure reduces the number of normal finger, it is still readily accepted by patients and is thought to be an ideal candidate for thumb reconstruction. Brunelli et al. 7 suggested that pollicization should be the first choice for amputations proximal to the metacarpophalangeal joint when four and even three fingers are present. It is the easiest and safest operation that supplies the best results both in terms of motor and sensory function. The index finger is preferred because it can be pollicized without living a palmar scar and without creating tendon, vessel, or nerve crossover.
In this case, the patient had an amputation at the first metacarpal level in conjunction with the bone defect of the second metacarpal and proximal part of index finger. The first dorsal and volar interosseous muscles and the thenar muscles were also lost. Considering the loss of thumb and the dysfunction of index, we decided to use index finger pollicization combined with an anterolateral thigh flap to reconstruct the thumb. The innate blood vessels, nerves, and tendons were reserved completely to guarantee high survival rate, fewer complications, good function, and an esthetically pleasing shape.
If the index finger is damaged, it is preferred to leave one sounder finger or toe; the thumb is shorter than the other fingers, and its mobility is very important at the trapeziometacarpal joint. It is less important at the metacarpophalangeal and interphalangeal joint levels. In this case, the proximal part of the first metacarpal bone was retained; therefore, we jointed the remnant metacarpal with the proximal phalanx of index finger. The tendons of the index interosseous muscles can be sutured to the intrinsic muscles of the thumb. In this manner, the new thumb will have a normal size, only two phalanges, only one extrinsic flexor, and normal insertion of the muscles of the thumb.
As for the proper timing for the second surgery, we suggest that 7–14 days after the first surgery might be suitable. The VSD could continuously enhance the drainage of inflammatory exudate and promote the wound microcirculation, effectively decreasing the rate of wound inflammation and increasing the growth of granulation tissue. The elimination of inflammation and growth of granulation tissue provide the surgical basis for the success of the second operation. In this study, 10 days after VSD drainage, the growth state of granulation tissue and survival of surrounding soft tissue was determined. After another debridement, the combined surgery of index finger transfer, ligament suture, and flap transfer was done. It is beneficial to reduce the probability of wound infection and tissue edema, and thus increase the survival rate of the transferred tissues effectively.
In the operation, we should also pay attention to the following points: (1) we should properly dissect the neurovascular bundle of the index finger to ensure sufficient length of the nerve vascular pedicle, avoiding improper tension and compression of the bundles; this will ensure blood supply to the finger and avoid necrosis of the transferred finger; (2) the tendon tension should be adjusted in the operation. The flexor digitorum profundus tendon of the transferred index should be cut and sutured with the flexor pollicis longus tendon, and the extensor digitorum tendon cut and sutured with the extensor pollicis longus to ensure a proper tension. If the flexor and/or extensor tendon of the original thumb is missing, it should be replaced with the flexor and/or extensor tendon of the transferred index finger; however, the tension should be adjusted to restore the function of the thumb; (3) the interosseous and lumbrical muscles of the index should be preserved as much as possible; therefore, the adduction activity of the transferred thumb can be retained to a certain extent, avoiding the deviation of thumb to the digitus medius; and (4) the transferred thumb has the sensation of allachesthesia; therefore, postoperative sensory training and motion training should be carried out to restore the sensation and motion function of the thumb.
The advantages of pollicization include improved appearance and motion of all thumb joints. 5 The disadvantage of pollicization is a decrease in the number of digits and possible decrease in grip strength. 5 This disadvantage, however, may be compensated for by the reconstruction of a nearly normal thumb. We propose that an optimal indication for pollicization is loss of the thumb at the first carpometacarpal joint with a concomitant injured index. The injured index finger should be used for thumb reconstruction. Total hand function can be improved by the index finger pollicization.
Footnotes
Declaration of conflicting interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.