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Proximal femoral allografts and tumor prostheses offer pros, cons for revision
Femoral allografts allow attachment of soft tissues, but tumor prostheses halt disease transmission.
When managing proximal femoral defects during hip revisions, surgeons must decide whether to handle the case with a proximal femoral allograft or tumor prosthesis, according to an orthopedic investigator.
Allan E. Gross, MD, FRCSC, OOnt, of Mount Sinai Hospital in Toronto, discussed important aspects to consider before using either approach during a presentation he made at the Annual Current Concepts in Joint Replacement Spring 2008 Meeting.
“The advantages of structural femoral allografts over tumor reconstructions are you can restore bone stock and … can reattach soft tissue and the greater trochanter to a proximal femoral allograft, whereas you can’t [attach] very effectively to a tumor prosthesis,” Gross said.
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A femoral revision component was cemented into femoral allograft in this revision case. The surgeon split the femur sagittally to implant the construct and fixed it with cerclage wires to enhance host-to-graft union. Images: Gross AE |
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Allograft revisions
Indications for using a proximal femoral allograft or a tumor prosthesis vary based on diaphyseal involvement and type of defect, but allografts can almost always be revised later to a tumor prosthesis and usually do not burn any bridges, Gross noted.
With tumor prostheses, “You still need diaphyseal bone for fixation as opposed to the proximal femoral allograft,” he said.
His guidelines for selecting proximal femoral allografts included the fact that “there is no violation of host bone … with cement or a long, porous coat.” While revisions of allografts are by no means easy, Gross said he finds them easier than revising a prosthesis fixed with cement or a porous coating.
Faster rehab
Gross discussed some advantages of tumor prostheses for uncontained femoral defects greater than 8 cm in length. “There is no risk of disease transmission. There’s no resorption and it is a faster and easier rehabilitation,” he said. Rehab and weight-bearing are usually restricted with allografts until graft-to-host incorporation is complete.
The chief disadvantage of a prosthesis: The host canal becomes violated with cement or a porous-coated stem. “There is a much higher rate of dislocation with tumor prostheses because you are unable to reattach the greater trochanter with its muscles,” Gross added.
His technique for cementing an implant into an allograft with antibiotic-impregnated cement involves stripping the vastum from the septum, reflecting it anteriorly, doing a trochanteric slide osteotomy to preserve the posterior structures and splitting the femur sagittally. At the back table, Gross cements the implant into “an absolutely impeccable” allograft surface, but does not cement it to the host. Occasionally he wraps residual bone around the allograft at the junction to enhance union and vascularity.
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Gross said his revision hip arthroplasty technique using proximal femoral allografts does not compromise host bone with cement or a prosthesis with a long coated section. |
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Study results
Among the 93 proximal femoral allografts Gross and colleagues used in 92 patients, 86 individuals were evaluated with a final follow-up of nearly 18 years. Follow-up mainly consisted of radiographic graft evaluation of allograft-host union, trochanteric union, stability, graft fracture, resorption and survivorship.
The success rate was about 83%, with success defined as stable implants that did not require revision surgery, Gross said.
Failure rates were 5.9% for aseptic loosening and 4.4% for infection. Rates of nonunion and dislocation were 5.5% and 9%, respectively, and 10.7% of proximal femoral allografts needed revising.
For more information:
- Allan E. Gross, MD, FRCSC, OOnt, can be reached in the Division of Orthopaedic Surgery at Mt. Sinai Hospital, 600 University Ave., Suite 476A, Toronto, Ontario M5G 1X5, Canada; 416-586-4800, ext. 4611; e-mail: allan.gross@utoronto.ca. He is a paid consultant to Zimmer Inc.
References:
- Blackley HR, Davis AM, Hutchison CR, Gross AE. Proximal femoral allografts for reconstruction of bone stock in revision arthroplasty of the hip. A nine to fifteen-year follow-up. J Bone Joint Surg (Am). 2001;83(3): 346-354.
- Gross AE. Proximal femoral allografting & beyond: When all else fails. #95. Presented at the 9th Annual Current Concepts in Joint Replacement Spring 2008 Meeting. May 18-21, 2008. Las Vegas.