The goal of replantation (commonly known as re-implantation or re-attachment surgery) after traumatic amputation is successful restoration of function. Simply returning circulation to an amputated part does not in itself define success. The aim of both the patient and the surgeon is useful function and restoration of sensation - replantation of a part that will not perform useful activity should be avoided.
Traumatic hand and digit injuries can be a difficult difficult to reconstruct, and as Millard pointed out in Principalization of Plastic Surgery, replacing defects with like tissue results in the best outcomes. And rarely is there other tissue in addition to the the amputated part that is superior aesthetically or functionally, providing the amputated part is in good condition.
With the advancement in microsurgical techniques replantation has become more common, and can be performed with great success both aesthetically and functionally. Replantation of amputated parts has been performed in amputated fingers, hands, forearms, feet, amputated ears, avulsed scalp injuries, an amputated face, amputated lips, amputated penis and even in an amputated tongue. These injuries can arise from multiple potential etiologies including trauma (often industrial), machine injuries, assault or even self-mutilation. We will focus on finger and upper extremity replantation here since they are much more common than other amputations.
Decision making in replantation must take multiple factors into consideration. Whether to proceed requires an assessment of the patient, including history, physical examination and medical co-morbidities and occupation. An examination of the amputated part(s) and of course the affected limb is required to understand the extent of injury and potential for success and useful functional outcome. The feasibility of replantation may not be certain on gross inspection and may not be apparent until after surgical dissection intraoperatively.
A radiographic evaluation is invaluable for the assessment of the extent of bone injury and or loss.
The indications for replanation have broadened over the last decade, as we have gained experience attempting to salvage more complex injuries. The following are indications for replantation:
Contraindications to replantation include:
The indications and contraindications are not absolute, and the decision for replantation is best made by the patient and physician after a discussion of the potential outcome, benefits, risks, possible complications and available alternatives to the replantation. This discussion is very dependent on the surgeons judgement of the potential outcome in a given patient.
The amputated part is aseptically prepped and surgically exposed/tagged under loupe magnification. This can be done before the patient is asleep on a separate tagging table. The patient can be brought into the operating room and the amputation site is aseptically prepped and draped. The site is surgically exposed/tagged under loupe magnification after induction of anesthesia. If replantation is indicated and possible it proceeds in the following order:
The order can be changed is the anatomy and configuration of the injury preclude proceeding as above. For instance, a part with a volar skin bridge that would impede arterial repair after bone and tendon repair may need arterial repair first, followed by tendon and nerve repair. Partial placement of k-wires or plates may be helpful in this situation, with completion of fixation after arterial and tendon repair.
If the part is deemed to be replantable, bone fixation is performed first. Most commonly, fixation with k-wires is performed. The wires span the site where the bone has been cut, to hold the bone in rigid fixation. Some surgeons prefer interosseous wires, and no method is superior to another. They are surgeon and situation dependent.
Internal fixation can sometimes be performed if the anatomy and surgeon comfort allow it. The advantages of plate fixation include no k-wire exit sites, more rigid fixation and easier early mobilization post-operatively. Disadvantages include increased operating time and the requirement for increased bone stripping to expose bone for plating.
External fixation can be performed in selected cases where bone destruction is significant, where potential soft tissue contracture can be avoided by external fixation, or when contamination of plates or k-wires is likely.
After rigid fixation is performed, the flexor tendon/muscle units are repaired. The arm and parts are still avascular with a tourniquet inflated, and delicate structure like nerve and vessels are deferred so as not to be damaged or pulled apart during these more macro maneuvers.
The timing of extensor tendon repair is variable. At this point the dorsal tendon can be repaired, or this can be deferred until just before the venous repair if well exposed tendons are present. If numerous tendons are present or difficult repairs are anticipated or it is anticipated that the tourniquet would be deflated before tendon repair, then the extensors should be repaired immediately after flexor tendon repair.
If nerve repair will not interfere with arterial repair, nerve repair is best performed next. If the artery repaired is performed first, and the tourniquet is deflated, nerve repair is much more difficult in a blood filled field.
The microsurgical repair of an artery can now be performed. Removal of the vascular clamps reveals whether circulation can be re-established to the amputated par. Typically, an anticoagulant is begun intravenously, like dextran.
If a major replantation like a hand or arm is replanted, venous oozing can be significant and must be accounted for by the surgeon and anesthesiologist. For major replantations (arm), blood products are often begun at this point.
The venous system is repaired next, unless extensor tendon repair has been deferred. For fingers, one vein is typically repaired. For a hand or arm, one large vein must be repaired. This is usually the saphenous vein.
The skin is then closed, often with a skin graft, depending on the swelling and the nature of the injury. If the injury is major, and there is exposed tendon, nerve or bone, the wound is dressed and definitive closure can be performed in a delayed fashion if the part survives.
The hand is usually placed in a splint and the patient is monitored closely for circulatory changes in the finger during the post-operative period.
Patients are admitted to the hospital and monitored for perfusion disturbances in the replanted part. Monitoring is performed by the nursing staff and microsurgical team. Any change in perfusion is addressed according to the etiology of the disturbance. Treatment may be as simple as removal of restrictive dressings or repositioning a patient to promote venous drainage. Medical management of perfusion with anti-coagulants can be changed according to the patient's response, especially with medicinal leeches and heparin. Operative re-exploration may be performed in certain cases depending on the etiology and the potential for reversal with intervention with microsurgery.
Most patients who have undergone replantation are treated with some form of anticoagulation. Aspirin and Dextran are typical in our institution. Leeching may be necessary for venous insufficiency. For more details on anti-coagulation see here.
During hospitalization, consultation with an occupational therapist is initiated. Post-operative therapy is critical to success, and a patient that does not put full effort into this rehabilitation is very likely to do poorly. Therapy is continued with an outpatient program after discharge.