Limb Replantation
When an arm is replanted care is taken to return
all structures to their normal positions and then repair them. Often, depending
on the mechanism of amputation additional vascularized tissue is needed to
provide soft tissue cover of vital structures. Unfortunately, this does not
result in adequate function is all cases.
Limb amputation obviously involves all muscle
compartments at the level of injury. Because of this, local muscles are not
always appropriate for transfer. One option available for patients with upper
arm replantation and loss of elbow flexion is distant muscle transfer. If
available, the ipsilateral latissimus muscle can be transferred from the back
onto the arm to restore elbow flexion. No vessel or nerve repair is required in
this situation. When this is not an option or when function is lost below the
elbow, a muscle has to be transplanted with microneurovascular anastomosis to
restore function.
FMMTs can be used to restore elbow flexion, wrist
extension, wrist flexion, finger extension, finger flexion or a combination
thereof. Even if the FMMT is successful in the upper extremity replant, injury
to the ulnar nerve often dictates the ultimate functional return of the hand. If
the ulnar nerve is irreparable, additional surgeries will be required to
rebalance the hand. Review ulnar nerve palsy for details.
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Major Soft Tissue Loss
Synergistic muscle compartments can be mechanically
lost secondary to traumatic crush/avulsion, Volkmann’s ischemic contracture, or
after surgical resection for malignant tumors. Acute care for these injuries
entails bony stabilization, revascularization, and possible compartment release
or fasciotomy. Given the nature of the injury, serial debridement is necessary
until all questionable tissue is removed. Grafting of nerve or bone is deferred
until control of the wound. Often vascularized tissues need to be transplanted
to accomplish this.
When the wounds are healed and FMMT criteria are
met, a functional muscle can be transplanted to restore active motion across the
joints of the upper and lower extremities.
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Major Nerve Injury
Major peripheral nerve injury will result in loss
of synergistic muscle function. The first approach is primary nerve repair or
nerve grafting. When this is not possible, or repair has failed and resultant
muscle atrophy has occurred, a FMMT can be employed.
Common examples include brachial plexus or common
peroneal nerve injury. Surgical intervention such as nerve exploration and
repair or grafting has resulted in less than optimal restoration of function.
The reason for this is unclear. However, it is believed that their “mixed”
sensory and motor character results in fascicle mismatching. Specific nerve
stains have been employed to identify the motor component for transplant
innervation.23 The gracilis transplant to the anterior compartment has restored
foot dorsiflexion and the ability to walk without dependence on ankle splints in
a selected group of our patients.
Patients with devastating injuries to their upper
and lower extremities should be evaluated by a reconstructive microsurgeon as
well as a prosthetist. A complete understanding of the functional potential
provided by each must be understood before embarking on either. In selected
patients functional microvascular muscle transplants can restore function and
allow patients to return to their daily activities.
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