Cortical Strut Bone Grafts
David G. Lewallen
Cortical strut grafting of the femur during revision total hip arthroplasty (THA) can help reconstruct bone defects and restore bone stock, eliminate stress risers which might cause later fracture, provide stable fixation of periprosthetic fractures, and can reduce pain from mechanical mismatch of the bone and implant at the tip of some femoral components.
Disadvantages include expense, increased associated infection risk, need for greater exposure, and chance of devascularization of the host bone, irritation of overlying soft tissues, possible graft resorption, and occasionally adjacent joint stiffness from scarring of the soft tissues.
Strut grafts may be applied as needed along one cortex or double strut grafts may be applied either medial and lateral or at 90° to one another (usually on the anterior and lateral cortices) (Figure 35.1).
Strut graft union rates to the host bone are high as long as contouring and host bone contact are good and reasonable efforts are made to respect and preserve remaining soft tissues attachments to the underlying femur as much as possible.
Excessive stripping of soft tissues from the host bone can prevent healing of any fractures of the host bone and can impair allograft incorporation.
Sterile Instruments and Implants
Standard revision hip instruments and retractors are needed to facilitate extended femoral side exposure.
A large segment cortical strut allograft (usually from the femur) of adequate length and size to complete the reconstructive plan and provide distal extension well on to the intact portion of the host bone is needed.
A saw and high-speed burr are both needed to allow strut graft preparation and contouring.
Fixation of the strut graft is accomplished by cerclage wires, cables, or plastic loops with instrumentation for insertion of the planned cerclage type a requirement.
It is important to have many more cerclage devices available on hand than would likely be needed in the event the initial fixation of bone or strut grafts is suboptimal and must be redone.
Any surgical approach used for revision THA including the posterolateral, direct lateral, and extended trochanteric version of these approaches can be adapted to allow strut grafting as needed.
Often struts are placed onto areas exposed distally along the diaphysis of the host bone by either longitudinal splitting or reflection of the vastus lateralis anterior-ward.
A concerted effort must be made to limit the extent of soft tissue stripping off of the femur to that required for strut graft contact on host bone—and no more—in order to avoid devascularization of the femur.
Planning for potential strut graft use is reasonable when there are major segmental or cavitary femoral bone defects that compromise or threaten the integrity of the proximal femur and associated muscular attachment sites like the trochanter.
Strut grafts are a useful tool for spanning stress risers due to boney defects or stress risers created by the tip of the femoral implant. The strut grafts can help reduce the risk of subsequent fracture especially in patients with impaired bone quality (Figure 35.2).
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