|Microsurgery: Transplantation and Replantation by Harry J. Buncke, MD, et al.|
| Amputation distal to the sublimus tendon attachment has an excellent prognosis for successful replantation. If the amputation is through the DIP joint, shortening and fusing the DIP joint simplifies replantation and yields excellent results. Replantation of distal amputation restores the specialized fingertip tissues, reduces or avoids neuroma and painful fingertip problems, and is cosmetically more satisfactory than an amputation stump.
In replanting of multiple digits amputated through the PIP joint, the joint should be fused at a 45-degree angle of flexion, and profundus-only flexor tendon repair and extensor tendon repair are performed. This restores good opposition, pulp-to-pulp pinch, and grasp function, even with MP joint motion alone. After the thumb, ulnar digits are replanted first because they augment the grip by preserving the breadth of the palm.
Understanding the pathomechanics of these injuries ensures a more sophisticated and thoughtful treatment of these injuries. Proper selection and treatment of some ring-avulsion injuries yields good results. Indications for replantation include intact sublimus insertion, undamaged PIP joint, undamaged distal vessels, and degloved skin suitable for revascularization and coverage. The surgical techniques required for success include adequate debridement of neurovascular structures and skin, bone shortening and fusion of DIP-level bony amputation, liberal use of vein grafts, and use of local flaps and skin grafts to protect the proximal portion of the replant. Usually, one artery and two veins must be repaired.
If adequate wound healing has occurred, rehabilitation can usually be started within 10 days. Rehabilitation is vital to avoid PIP joint stiffness and flexion contracture that often follow ring-avulsion replantation. (See Chapter 42.)
A palmar incision similar to that used for carpal tunnel release helps expose the flexor tendons and the median and ulnar nerves for proper identification and tagging before the surgical repairs.
Maintaining the delicate balance of flexor and extensor tendons must be the goal when replanting a hand. In subtotal amputation with bone loss, bony shortening up to 3 cm or 4 cm is acceptable. Further shortening, however, causes tendon imbalance and seriously compromises hand function. Therefore, although bone shortening can simplify soft-tissue coverage, neurovascular repairs, and bone fixation, if it is incautiously done, hand function will be poor. Only with total amputation, in which both the extensor and flexor tendons can be shortened and balanced appropriately, can the bone be shortened by more than 4 cm.
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