Although the replantation of a hand is certainly spectacular, it may seem less demanding technically than a digital replantation. There are, however, many problems that remain to be solved, given the possibility of muscle ischemia, technical choices related to osteosynthesis of the radiocarpal and carpometacarpal skeleton, revascularization requirements, nerve repair and, finally, the treatment of soft tissue defects that accompany this type of trauma.
General Principles
Functional Outcomes
Since the first arm replantation performed by Malt in Boston in 1962, it has become apparent that the quality of functional recovery is directly related to the quality of nerve regeneration. It is conventional to define the level of amputation based on radiologic criteria that specify the location of the fracture. Our experience is different and shows that replantation criteria should be based primarily on the level of nerve injury and not on that of the bone fractured.
The problem is not only ensuring survival of the limb but also its functional outcome. It is fairly standard to observe a disarticulation of the hand in the wrist with a nerve avulsion in the forearm, as a disarticulation of the shoulder with avulsion at the level of the brachial plexus.
The primordial importance of nerve recovery calls for a primary nerve repair technique without tension, even at the cost of shortening the skeleton.
Our experience also confirms the experience of other teams regarding the functional outcome according to the level of amputation. Proximal amputations—in other words between the lower third of the forearm and the carpometacarpal joint—have a functional outcome that is better than distal transmetacarpal amputations. At this level it is difficult to hope for recovery of the intrinsic muscles, and tendon and neurovascular repair is technically more difficult.
Injury Assessment
The initial assessment must specify the mechanism of injury: clean-cut amputation, crushing or avulsion mechanisms, singly or in combination. Machine withdrawal maneuvers may be added to these mechanisms, which cause additional elongation injuries.
Clean amputations are rare, and injury levels vary depending on the elastic resistance of the tissues, which is not the same for the arteries, veins and nerves.
The replantation strategy is linked to the injury mechanisms. It is different for a clean amputation, an amputation by crushing or by avulsion, and different injury mechanisms can be combined.
General Assessment
The patient’s general condition must be thoroughly evaluated to confirm an indication for replantation.
The clinical history will clarify whether this is a single trauma, because it is hardly possible to carry out a replantation for several hours if the injured person has also sustained a head, chest, abdominal injury and so on. Blood loss should be known because a hand replantation at the moment of releasing the tourniquet may generate significant blood loss. Age, diabetes and smoking are factors directly influencing the success rate and quality of functional outcome.
Furthermore, it is important to determine the actual functional contribution the replanted hand will bring to a manual worker with high functional demands. Whereas a clean amputation will give a higher functional outcome compared with the best prosthetics, this is not the case for an avulsed hand, where the nerves can only be repaired by grafting.
In women, for aesthetic reasons, there are fewer contraindications for replantation than in the manual worker, where it is important to explain the limitations of this surgery and the disability that may represent an insensitive and nonfunctional hand.
With microsurgery it is almost always possible to replant a hand, but sometimes it is a mistake to be extreme about it. It is only through the experience of the surgeon that we acquire rigor in the indications.
Care of the Amputate
We have reviewed the conditions for preservation of amputated fingers in Chapter 15 . Any error causes complications, even contraindications to replantation, and only repeated education can prevent this.
Recall that the amputated limb should be surrounded by a dressing and then enclosed in a sealed plastic bag and placed on ice to protect the tissues against anoxia by bringing them to 4°C ( Fig. 16.1a ).
For the stump, it is usually not necessary to set up a tourniquet, which could potentially create a second level of injury. A simple compression bandage is enough to ensure hemostasis of the radial, ulnar and possibly interosseous arteries.
Definition of Amputation
This chapter is devoted exclusively to complete amputations of the hand. It is important to differentiate between amputation and devascularization. In the latter case there is a continuity of certain tissue components (skin, tendon, etc.) that will change the prognosis, although the hand is completely devascularized. Indeed, these tissues in continuity often ensure venous and lymphatic return. It is therefore essential during débridement to preserve these tissue bridges.
Revascularization techniques have been elaborated in Chapter 8 . Our purpose here is to present the technique of replantation of a completely severed limb ( Fig. 16.2 ).
Consequences of Ischemia on the Amputated Hand
Circulatory arrest in the amputated hand has important but variable consequences depending on the tissues involved.
The anoxia associated with catabolites can lead to permanent tissue damage. This explains the importance of limiting these effects by carrying out perfect hypothermic preservation and quickly revascularizing the tissues (see Chapter 2 ).
The skin and subcutaneous tissue are particularly tolerant to ischemia insofar as refrigeration at 4°C is carried out. We were therefore able to successfully replant the scalp of a 4-year-old who had to travel more than 1000 km to reach our service.
Anderl also reported a case of free groin flap transfer which had been preserved with a cold ischemia time of 30 hours.
Bone ischemia is quite well tolerated in adults for the first 4–5 days according to Albrektsson. However, it seems that after 12 hours of ischemia, there will be a delay in callus formation. In children, tolerance to ischemia is lower because the growth cartilages are altered at the end of the second hour.
The wall of the lymphatic vessel deteriorates from the eighth hour onward. After replantation, reorganization begins on the fourth postoperative day, to be functional between the 8th and 14th days.
Ischemia of the peripheral nervous system leads to numerous metabolic disturbances from the eighth hour onward, in particular in the blood-neural barrier, axonal conduction and the motor end plate. The edema that sets in brings about a true compartment syndrome. After revascularization, to avoid the harmful effects of edema, it is fundamental to perform a fasciotomy of all the compartments of the forearm and intermetacarpal spaces and to free the median nerve in the carpal tunnel and the ulnar nerve in Guyon’s canal. However, it is not necessary to carry out an intraneural neurolysis, which may impair the vascularization of the nerves.
Muscle is also very sensitive to ischemia. It is necessary to ensure a blood flow of 1.35–6 mL/min per 100 g of muscle to maintain its metabolic activity. Ischemia creates anaerobic conditions conducive to metabolic acidosis and then superinfection. The accumulation of catabolites in the muscle mass must be taken into account at the time arterial circulation is restored. To avoid returning these catabolites into the general circulation, which creates significant disorders of peripheral vascular permeability, it is prudent not to perform reanastomosis of the venous system until the replanted hand has been “washed” with arterial blood, flushing out the catabolites.
It is remarkable to observe the venous return for the first minute of recirculation, which is burgundy in color. During this period, vasodilation is established, causing significant blood loss that needs to be noted by the team of anesthetists. If there has been a long period of ischemia of the muscle mass at the stump, it is prudent to carry out an excision to prevent necrosis and secondary infection. In the hand, fasciotomy of all the interosseous muscles is essential to limit the effects of edema, which sets in after revascularization.
Technical Principles
Preparation of Extremities
Distal Extremity
After the patient is stabilized, the surgical team prepares the hand to be replanted. It is x-rayed so as to plan for the eventual fixation. The hand is initially brushed and washed with a nonstaining antiseptic solution. If the hand is stained with grease, it is useful to eliminate this with ether to facilitate postoperative monitoring of vascularization.
The skin débridement removes bruised or permanently devitalized tissues. Skin incisions should make it possible to perform fasciotomies and expose structures for repair.
In proximal amputations, an anterior incision opens up the antebrachial compartments and extends into the carpal tunnel. It is here that all the tendons are easily identified, as well as the median nerve, then the ulnar nerve and the artery after opening Guyon’s canal.
The radial artery is approached either in the radial groove (if the amputation passes through the lower third of the forearm) or at the apex of the first dorsal interosseous space (if the amputation is more distal). If the amputation is transmetacarpal, a palmar approach may be carried out either by elevating a distally based flap or by multiplying Brunner-type incisions.
After this palmar preparation, all of the palmar and neurovascular tendon elements are identified and sufficiently dissected to allow repair. In the case of contusion, a careful examination under loupes or under microscopy will determine the level of resection. In this case we must determine how much shortening of the skeleton is required to facilitate nervous and vascular repair without tension. If the shortening is excessive and leads to a functional and aesthetically unacceptable impairment, the technical alternative is to resort to vascular repair and nerve grafts, the latter performed secondarily.
Preparation of the dorsal surface of the hand is faster because the extensor tendons are easily identified. It is the same for the sensory branches of the radial and ulnar nerves.
The venous system is also easily identifiable, with the requirement to use veins that are not bruised.
Appreciation of the potential viability of the dorsal skin is more difficult because the reverse flaps created by trauma often become necrotic. It is therefore prudent after this preparation to consider alternative solutions for covering the extensor apparatus and venous repairs.
The dogma widely circulated at the beginning of replantation surgery—repair of two veins for one artery—has faded out. In complex trauma it is difficult to find more than two veins that allow a direct suture without grafting. Our experience has shown success with one repaired vein, knowing that a new venous network begins to form from the fifth postoperative day.
After preparation of the hand, it is essential to ensure that palmar and dorsal fasciotomy of the interosseous muscles is performed to prevent compartment syndrome.
In proximal amputations, all nonvascularized muscle attached to the tendons must be excised because it will degenerate into a fibrous block.
Proximal Extremity
Preparation of the proximal stump is performed under pneumatic tourniquet after washing, brushing, débridement and fasciotomy. The tendon and neurovascular elements are isolated, and their identification ensures anatomic repair with the correct distal structures in the amputate (see Fig. 16.2e ).
Dissection of the neurovascular structures should be limited to the minimum necessary to ensure microsurgical repair. The vessels are observed under a microscope for contusions of the wall or subadventitial rupture.
Before replantation it is prudent to test the quality of blood flow. This step is especially important when the mechanism of trauma has been an avulsion. A subadventitial rupture situated remotely from the amputation can stop any flow, so grafting has to be performed.
Stabilization of the Skeleton
This is a critical step that requires selection of reliable, fast and solid techniques, protecting the patient from implant failure, a source of osteomyelitis and pseudarthrosis, which is always difficult to treat secondarily.
Bone shortening ranges from a few millimeters to several centimeters so as to allow a repair without tension of the vessels and nerves.
Osteosynthesis of the distal third of the forearm is resolved by compression plates.
If the amputation is in the distal radioulnar joint, it will be necessary to consider a resection of the lower extremity of the ulna (according to Darrach) or arthrodesis-arthroplasty (according to Sauve-Kapandji) so as to preserve pronosupination.
A more distal amputation may require a proximal row carpectomy. For preservation of wrist mobility, it is preferable to maintain a distraction of this new radiocarpal joint using an external fixator.
It is also important to preserve the palmar and dorsal capsuloligamentous apparatus for reinsertion so as to ensure the stability of the neoarticulation.
The advantage of osteosynthesis techniques by external fixator is the easier resolution of the problem of skin coverage in these complex traumas.
Stabilization of the radiocarpal skeleton may also be ensured by Steinmann pins inserted through the second and third intermetacarpal spaces or by a Rush nail inserted by an in-and-out technique through the capitate and through the third metacarpal into the diaphysis of the radius. This method may provide a temporary arthrodesis for a proximal row carpectomy but also a permanent arthrodesis according to Mannerfelt’s principle. In this case the locking of the construct is ensured by an antirotation Kirschner wire or a radiocarpal blunt clip (see Fig. 16.1d ).
In wrist fractures the carpal bones are often enucleated or pulverized. It is therefore legitimate to consider a direct osteosynthesis from the base of the metacarpals to the radius using axial pins. The metacarpals are held together beforehand by a transverse Kirschner wire.
Transmetacarpal amputations receive an intramedullary osteosynthesis using part of a Steinmann nail (2–3 mm in diameter) accompanied by an antirotation oblique wire. This method is fast and provides a good solid fixation.
Another possibility is the use of osteosynthesis plates. They provide a very stable fixation but take a relatively long time to apply, extending the period of ischemia (see Fig. 16.2d ).
If the transmetacarpal amputation is oblique, the metacarpophalangeal joint of either the index or little finger may be destroyed. It is therefore possible, if the skin surface is of good quality, to ensure its emergency prosthetic replacement with a DePuy Neuflex implant.
Revascularization Techniques
In Distal Amputations
During transmetacarpal amputations, it is not always possible to perform a direct repair of the superficial palmar arch or the digital arteries. In this case a vein graft restores the arch of the ulnar artery, and the digital arteries are anastomosed end to side with the graft.
If the superficial palmar arch is intact, the surgeon can mount two end-to-side vein grafts that will be anastomosed with the common digital arteries of the second and fourth spaces. The digital artery of the third space does not have to be repaired because the middle finger is revascularized by the digital artery of the second space.
To avoid multiple grafts when the superficial palmar arch is destroyed, we use the superficial venous arch of the dorsum of the foot, with its divisions. This will be anastomosed to the radial and ulnar artery, and the branches directly with the digital arteries ( Fig. 16.3 ).
