Fri., 10/17/08 Basic Science, Paper #17, 9:36 am OTA-2008
•Use of the Reamer-Irrigator-Aspirator for Bone Graft Harvest: A Mechanical Comparison of Three Starting Points in Cadaveric Femurs
Ryan P. Finnan, MD (a-Dayton Area Graduated Medical Education Consortium (DAGMEC)
Grant); Michael J. Prayson, MD (a-Synthes, Canica, I-Flow and Dayton Area Graduate Medical
Education Consortium (DAGMEC) Grant; a,b-Smith + Nephew);
Tarun Goswami, DSc (n); Danielle Miller, MSb (n);
Wright State University, Department of Orthopaedic Surgery and Department of Biomedical,
Industrial and Human Factors Engineering, Dayton, Ohio, USA
Purpose: Our objective was to evaluate the mechanical behavior of cadaveric femurs after intramedullary (IM) reaming using the reamer-irrigator-aspirator (RIA) for autogenous bone graft harvest via three conventional starting points without subsequent IM stabilization. We hypothesized that reamed femurs, regardless of starting point, would adequately withstand cyclic axial loading simulating postoperative ambulation.
Methods: 21 cadaveric pairs were randomly assigned to one of three groups (based on starting point), and then each cadaver’s femurs were randomly assigned as the control or study specimen. Starting points for the reaming and group designation were as follows: group 1, trochanteric; group 2, piriformis fossa; and group 3, retrograde. Each femur underwent dual energy x-ray absorptiometry scanning and was radiographed. Each test femur was reamed to 15 mm using the RIA via a single-pass reaming technique. The contralateral femur from each pair served as the unreamed control. The specimens were loaded to 1400 N of axial compression with 2° simultaneous torsion at a frequency of 2 Hz for 10,000 cycles. If the femur withstood cyclic loading, it was then loaded in axial compression to failure. Failure modes were recorded. Comparisons regarding survival of cyclic loading were made using Fisher’s exact test with alpha (statistical significance) of 0.05.
Results: There were no differences between groups regarding age, sex, and T-score. The mean T-score for the harvested femurs was –2.531 ± 1.372. Overall, 18 of 21 test femurs (86%) and 20 of 21 control femurs (95%) withstood cyclic loading (P = 0.606). In the trochanteric group, 7 of 7 (100%) of both study and control femurs withstood cyclic loading. In the piriformis fossa group, 5 of 7 study femurs (71%) and 6 of 7 control femurs (86%) withstood cyclic loading. In the retrograde group, 6 of 7 test femurs (86%) and 7 of 7 (100%) control femurs withstood cyclic loading. Statistical significance was not reached for any of the three pairwise comparisons between test groups. The femurs tended to fail in patterns consistent with simple pertrochanteric, basicervical, midcervical, or subcapital fractures (OTA 31-A1.1; 31-B2.1/3; 31-B3.3)
Conclusion: IM reaming for bone graft harvest using the RIA without subsequent IM stabilization did not significantly degrade the mechanical behavior of cadaveric femurs in simulated ambulation, regardless of reamer starting point.
Significance: It appears safe to allow weight bearing on a reamed, unstabilized femur after bone graft harvesting using the RIA.
If noted, the author indicates something of value received. The codes are identified as a-research or institutional support; b-miscellaneous funding; c-royalties; d-stock options; e-consultant or employee; n-no conflicts disclosed, and *disclosure not available at time of printing.
• The FDA has not cleared this drug and/or medical device for the use described in this presentation (i.e., the drug or medical device is being discussed for an “off label” use). ◆FDA information not available at time of printing. Δ OTA Grant.