The Journal of Bone and Joint Surgery (American). 2005;87:521-529.
doi:10.2106/JBJS.C.00759
© 2005 The Journal of Bone and Joint Surgery, Inc.
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 Adult Hip Reconstruction Test 13: Spring 2005
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Mechanical Effects of the Extended Trochanteric Osteotomy

Andrew R. Noble, MD1, Daniel B. Branham, MD1, Mark C. Willis, MD1, John R. Owen, BS1, Benjamin W. Cramer, BS1, Jennifer S. Wayne, PhD1 and William A. Jiranek, MD1

1 Departments of Orthopaedic Surgery and Biomedical Engineering, Orthopaedic Research Laboratory, Virginia Commonwealth University, P.O. Box 980694, Richmond, VA 23298. E-mail address for W.A. Jiranek: wjiranek{at}hsc.vcu.edu

Investigation performed at the Departments of Orthopaedic Surgery and Biomedical Engineering, Orthopaedic Research Laboratory, Virginia Commonwealth University, Richmond, Virginia

A commentary is available with the electronic versions of this article, on our web site (www.jbjs.org) and on our quarterly CD-ROM (call our subscription department, at 781-449-9780, to order the CD-ROM).

The authors did not receive grants or outside funding in support of their research or preparation of this manuscript. They did not receive payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, educational institution, or other charitable or nonprofit organization with which the authors are affiliated or associated.

Background: The extended trochanteric osteotomy was introduced as a safe and effective exposure technique for revision hip surgery; however, intraoperative iatrogenic femoral fractures have been reported. This study examined the effects of the extended trochanteric osteotomy on the torsional strength of the femur with use of cadaver bones. We hypothesized that repair of the osteotomy fragment would restore the torsional strength to that of an intact femur and that an osteotomized femur containing a well-fixed stem would have the same torsional strength as an intact femur with a stem.

Methods: Fifty-eight cadaveric human femora were divided into five groups, according to the repair technique, to examine the effects of the extended trochanteric osteotomy: intact, osteotomy, repaired osteotomy, implant, and implant-repaired osteotomy. Osteotomy fragments were reattached with use of three double-looped 18-gauge wires. A femoral stem was cemented into the last two groups. Specimens were tested mechanically in rotation until failure. Rotational properties were compared with one-way analysis of variance followed by post hoc pairwise comparisons. Linear regression analysis was performed for bone mineral density and torsional strength.

Results: Torque to failure was reduced by 73% for the specimens in the osteotomy group compared with the intact group (p < 0.0001). Repair of the osteotomy did not improve torque to failure (p > 0.99). Femora in the implant-repaired osteotomy group displayed significantly improved torque-to-failure values compared with the specimens in the osteotomy and repaired osteotomy groups (p < 0.0001). However, the strength of the femora in the implant-repaired osteotomy group remained significantly less than that of the specimens in the implant group (p < 0.007). A significant linear relationship was observed between bone mineral density and torque to failure for femora in the intact (p < 0.006), osteotomy (p < 0.002), and repaired osteotomy (p < 0.001) groups.

Conclusions: The extended trochanteric osteotomy reduces torsional strength by 73% even when the osteotomy fragment is repaired. Bone mineral density directly affects absolute femoral strength in this model.

Clinical Relevance: In this in vitro cadaver study, the extended trochanteric osteotomy resulted in a significant reduction of torsional strength and energy required for fracture. Femoral stem insertion with osteotomy repair significantly improved torsional strength; however, this construct remained significantly weaker than that of a femur that had an implant without an osteotomy. This finding suggests that postoperative rehabilitation protocols should be even more restrictive with regard to weight-bearing and the use of abduction braces after revisions with use of an extended trochanteric osteotomy than after revisions that do not require an extended trochanteric osteotomy.


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