Surgical procedure
Debriding of the necrosis tissue was first performed in the operation room and the arteries, veins, nerves, and tendons of the injured thumb were identified and isolated. The surgical plan was made according to the size and shape of the defect. The patient’s lifestyle and local condition of the donor site were also considered in the selection of the donor site.
The reconstruction method was chosen based on the thumb amputation level and patient’s career background. For the defects that involved the distal interphalangeal joint (no matter transverse, oblique or longitudinal defect), great toe to hand transfers were performed for thumb reconstruction as reported [6–8]. The second toe is smaller and shorter than the normal thumb in appearance, but can achieve better function than the great toe[9, 10]. We used the second toe transfer for patients who suffered metacarpal bone or proximal phalanx defects with higher demands for function and lower demands for appearance. For those who had higher demands for both appearance and function of the reconstructed thumb, the second toe phalange covered with the great toenail flap was used. Once the operation method was determined, Doppler was used to locate the donor and recipient vessels.
Donor site preparation: Incisions were made according to the design (Fig. 7a,b). Dissection was performed to isolate the first and second branches of the dorsal vein and achieve sufficient pedicle length. We then ligated the other vein branches and made incisions at the web and plantar areas to find the first plantar metatarsal artery, the digital nerve, and its branches. We had to next Confirm the toe web vascular type and isolate the blood vessels and nerves. If the dorsalis pedis artery was chosen for the anastomosis, isolation of the dorsal artery was performed and the deep plantar branches were ligated to achieve the blood supply model as the dorsal artery-the first dorsal artery-toe artery. Sometimes, the first dorsal metatarsal artery has variation. The dorsalis pedis artery-plantar artery-toe arterial blood supply mode should be maintained for type III dorsal metatarsal arteries. If the first plantar artery were chosen to perform the anastomosis, it would not have been necessary to consider the toe web vascular type or isolated the first dorsal metatarsal artery. The neurovascular bundle was then exposed and dissected together with the free flap. Ligation of the hallux cross artery was carefully performed and the second phalanx was cut according to the defect of recipient cite. This was followed by the isolation of the hallux and 2 phalange flap.
(1) Bone reconstruction: We used wires and Kirschner to fix the bones for earlier functional rehabilitation.
(2) Tendon reconstruction: After the second toe phalange with vessels, nerves, and tendons were fixed to the phalangeal bone of the thumb with Kirschner wire, the extensor tendon and the flexor tendons were repaired and put in their rest positions. If the original amputation included the proximal site of the metacarpophalangeal joint, the pollicis brevis tendon also needed to be repaired. To do accomplish this, two functions needed to be restored. The digital flexion function was restored by replacing the hallucis longus flexor and extensor tendons with the 2nd inherent extensor and the 4th superficial flexor tendons. The function of opposition was achieved by using a dynamic tendon as a substitute in a similar way.
(3) Nerve reconstruction: Nerves needed to be sutured under tension free circumstances. The proximal nerve avulsion defect was reconstructed by suturing the 2nd digital nerve (ulnar side) with the donor nerve.
(4) Vascular reconstruction: Anastomosis was done to complete the vascular reconstruction. Patients received end to end anastomosis through subcutaneous tunnels between the first dorsal metatarsal artery and the radial artery at the snuffbox, in addition to between the saphenous vein and the deep branch of cephalic vein. If the diameter of first dorsal metatarsal artery was too small or absent, anastomosis of the first plantar metatarsal artery and the finger inherent artery was done instead.
(5) Donor site closure: The second phalanx flap was then transplanted to the tibial side of the hallux and the exposed bone was covered with the hallux nail and skin flap. (It was important to keep the pedicle in tension free circumstances). The hallux flap was sutured to the skin on the second phalanx flap (Fig. 4a). For the distal thumb joint reconstruction, a full thickness skin graft on the great toe and direct closure of the 2nd toe were performed; the second toenail flap was used to cover the great toe defect in other patients.
The defect of the great toe was able to be easily covered by the second toe skin flap and thus the wound required no necessary skin grafts. The Figs. 1–5 show the surgical procedures and techniques.
Antibiotics, spasmolysis, and anticoagulation treatment were prescribed post operation. Normal daily activity of the foot started at 2 weeks post operation and rehabilitation of the reconstructed thumb started at 4 weeks post operation.
The Kirschner wire was removed at 6 weeks post operation after X-ray confirmation of bone healing. Distal interphalangeal joint fusion of the 2nd toe was achieved as planned. Bone fusion of the 2nd toe shortened the length of the reconstructed thumb to a final, close-to-normal size.
Rehabilitation: (1) X-rays were taken six weeks post operation to confirm the bone fusion and that the external fixation was removed. Passive and active functional exercises were also started at this time with a hand brace to avoid detrimental flexor and extensor tendon adhesions. (2) Electromagnetic waves were used at the reconstructed thumb pulp to stimulate nerve regeneration. (3) Iron therapy balls and 15 kg rubber bands were used to practice the thumb grip strength, pinch strength, and other muscle functions.
Rehabilitation Schedule: (1) Postoperative tendon adhesion is the main factor that negatively affects the reconstructed thumb function, but early functional rehabilitation minimizes this problem. The preparation stage starts 4–6 weeks post operation. In addition to passive movements for 5–10 minutes, 2 times a day, active movements were practiced with the guidance of a physician. (2) Continuous passive joint motion exercises were started 6 weeks post-operation and were done for four weeks. Initial activity was measured with a BTE Primus hand function rehabilitation assessment instrument. 5-10b traction strength was increased daily when there was no significant pain during the 30 minute exercise. Tendon release was performed if tendon adhesion occurred. (3) At 8–12 weeks post operation, the muscle strength training stage was begun. Isokinetic training was performed at 60 b/s, 90 b/s, and 120 b/s, 30 times a day. (4) 10–14 weeks post operation was the hand coordination training stage. According to the work characteristics of the patients, individually simulated vocational training was performed 30–60 min/day. Reassessment of the hand function was performed 6 months post operation. By individually simulating the patients with vocational training, we were able to prepare the patient to work once again.