Major Allograft or Autograft Transplantation Surgery
Background
Major segmental skeletal defects, particularly in the long bones
of the extremities, may occur as a result of tumor resection,[145]
trauma, or osteonecrosis. Repair of these lesions to eventually permit weight bearing
in the legs or restoration of mechanical function to the arms requires bone grafting.
Banked allografts obtained from living or dead donors or vascularized autografts,
usually of the fibula, are used to bridge resultant bony gaps[146]
[147]
( Fig.
61-6
). The duration of these procedures is long (2 to 10 hours), and many
candidates may be debilitated as a result of radiation therapy, chemotherapy, or
chronic infection.
Figure 61-6
Three months after en bloc resection and reconstruction
with a vascularized fibular graft augmented with autogenous cancellous graft using
external fixation for immobilization. (From Hsu RW, Wood MB, Sim FH, et
al: Free vascularised fibular grafting for reconstruction after tumour resection.
J Bone Joint Surg Br 79:36–42, 1997.)
Frequently, tumor resection is followed by immediate replacement
grafting. The surgical procedure consists of two phases for the anesthesiologist.
First, the surgical resection is often bloody, requiring attention to details of
fluid management and blood conservation and replacement. Second, subsequent fitting
of the graft and fixation to adjacent structures followed by wound closure may require
several hours of reconstructive surgery. Major anesthetic considerations are monitoring
requirements, fluid and transfusion therapy, and postoperative pain relief (see Table
61-5
). In longer procedures, meticulous attention to prevention of pressure
necrosis, neuropraxia, joint stiffness, and arthralgia is necessary.
Anesthetic Management
Whatever the choice of anesthetic technique, intraoperative hemodilution
combined with deliberate (induced) hypotension should be strongly considered because
it is desirable to limit blood loss and to provide as dry a surgical field as possible
during the procedure (see Chapter 47
and Chapter 48
). Preservation
of the vascularized graft is vitally important.[148]
[149]
The patient's temperature, circulatory
blood volume, and cardiac output must be maintained, and if possible, the graft flow
should be augmented by a sympathetic blockade. Other measures include intravenous
mannitol and anticoagulation with heparin. Postoperatively, these patients should
be kept in special care units so that the wounds can be monitored for graft patency
by visual inspection, Doppler flow probe, and pulse oximetry monitoring.
