Surgery

Digital amputation after clean-cut injuries does not have loss of tendon substance (Figure 46-1), but the level of tendon cut may not be the same as those in the tendons, particularly the flexor tendon. The proximal tendon ends retracted to the proximal phalanx or the palm. During crush and avulsion injuries, both flexor and extensor tendons can be avulsed from more proximal parts of the tendon (Figures 46-2 and 46-3). Additional incisions are needed to find the proximal ends and do end-to-end repair. In the thumb, both flexor pollicis longus (FPL) and extensor pollicis longus (EPL) tendons are usually cut without loss of tendon substance (Figure 46-4), and tendon avulsion from the thumb is also sometimes seen. Surgical priority should be given first to the bony fixation and re-establishment of vascular circulation. Ideally, tendons are repaired in all the cases. During replantation surgery, though slightly shortening of phalanges are necessary, tendons do not usually require shortening. Trimming the rugged tendon ends is required, which usually only produces about 0.5 cm shortening of the tendon substance.

Figure 46-1 A clean-cut total amputation through the middle phalanx of the index finger, presenting an ideal indication for repair of the flexor and extensor tendons. In this kind of tidy digital amputation, the phalanx was not shortened, and flexor and extensor tendons were repaired in the same way as usually do for clean-cuts of flexor or extensor tendons.

Figure 46-2 A crush-avulsion amputation of the index finger.

Figure 46-3 Both the flexor and extensor tendons were pulled out after disruption at the palm and wrist levels. The tendons were repaired through additional incision in the palm and wrist.

Figure 46-4 A, Thumb amputation distal to the IP joint. B and C, Both FPL and EPL tendons were repaired directly and the replanted thumb has good cosmetic appearance and function after surgery.

Both 2-strand Kessler and cruciate repair methods are now used popularly for flexor tendon repair (Figure 46-5). In our unit, we use a cruciate or an U-shaped four-strand repairs (Figures 46-5 and 46-6). We do not repair the FDS tendon. The FDS tendons are excised, because it is not possible to obtain good gliding and prevent adhesions after injuries to multiple tissues including bones involved in digital amputation. During surgery, we attempt to preserve the annular pulleys and synovial sheath as much as possible. Frequently, we incise or left open the sheath around the area of digital amputation. It is not possible to perform complicated pulley reconstruction during the replantation surgery, as this is not possible and lengthen the surgery. It is a practical way to leave completely disrupted annular pulleys open without surgical repair or reconstruction. It is not infrequent that we see that the A2 pulley is almost entirely damaged by the trauma, or is significantly shortened during surgery. In the case of thumb amputation, the FPL tendon must be repaired.

Figure 46-5 Two methods often used in flexor tendon repair during replantation surgery. A, Two-strand modified Kessler repair. B, Four-strand cruciate repair.

Figure 46-6 A four-stand repair method, i.e., the U-shaped repair, the senior author developed using a looped suture. A–C, Method of repair is shown. This is used to repair the FDP tendon during replantation.

As for extensor tendon repair, shortening of the digits has great impact on function of extensors. We usually manage to repair the extensor tendon with running continuous or locked running stitches or figure-of-eight suture. When phalanges are shortened, extensor tendons can be sutured with some overlapping of the cut portions.

Postoperative Care

To avoid disturbance to vascular circulation and ensure stable fixation of phalanges, replanted digits do not undergo early mobilization. For the first 3 or 4 weeks, the reattached digits are immobilized. After 3 or 4 weeks, the patients can be instructed to perform light passive motion of the digits. Active motion of the fingers can be started from 4 or 5 weeks (or even later) after surgery. Therapies should be given to lessen digital edema and improve digital circulation when the digit motion starts.

Outcomes

Recovery of active range of finger motion after digital replantation is generally poor. Many replanted digits have only limited active flexion. The specific reports that discussed digital motion range after digital replantation are rare. In our experience, we observed total range of active motion of the distal and proximal interphalangeal (DIP and PIP, respectively) joints of about 60° to 80° degrees of digital flexion. These degrees of motion in IP joints provide the hand with rather practical function for making a light grip or picking up. Powerful grip is usually not possible and making a full fist is rarely achievable. Joint stiffness occurs to a great percentage of the replanted digits. In our unit, we note varied degrees of finger joint stiffness (i.e., limitations in passive digital motion) in almost all the cases. Limitations of digital motion and function are actually due largely to the loss of passive digital motion range, rather than impaired tendon function.

A few reports indicated effectiveness of tenolysis after digital replantation. In 1989, Jupiter and colleagues reported 37 replanted digital units and four thumb replantations with a flexor tendon tenolysis at an average of 10 months after replantation.¹

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Gene Therapy for Tendon Healing Current Status and Future Primary Repair of the Flexor Pollicis Longus Tendon Molecular Biology of Tendon Healing Outcomes of Flexor Tendon Repairs and Methods of Evaluation Customizing Flexor Rehabilitation Based on Zone or Type of Injury

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