OTA 2008 Posters

Scientific Poster #91 Femur OTA-2008

Three-Dimensional Measurement of the Femoral Antetorsion: Technical Description and Comparison to the Conventional Radiologic Method

Daniel Kendoff, MD1 (n); Gil R. Ortega, MD, MPH2 (n); Musa Citak, MD3 (n);
Christian Krettek, MD3 (a-AO Foundation); Tobias Hufner, MD3 (n);
1Hospital for Special Surgery, New York, New York, USA;
2Sonoran Orthopaedic Trauma Surgeons, Scottsdale Healthcare, Scottsdale, Arizona, USA;
3Hannover Trauma Center, Hannover Medical School, Hannover, Germany

Introduction: One major problem in the treatment of femoral fractures is the high incidence of femoral torsion errors. There have been multiple techniques published relating to the measurement of the femoral antetorsion (AT) angle. A postoperative CT measurement of the femoral AT angle has been established as the best technique in evaluating reduction quality.

Purpose: The aim of our study was to produce a three-dimensional (3D) reconstruction of the same CT dataset and to compare it to the conventional method in terms of precision and dependence of femoral position in space.

Methods: A mechanical support was developed to rigidly fix the thigh bone in a designated position. After measuring the real AT, a CT scan in different femur positions was performed. 10 cadaveric specimens were examined. Every examination was performed twice and the mean value was computed. As the conventional method, the procedure modelled after Jend was chosen. In the 3D reconstruction, the angle between the femoral neck and trailing edge of the femoral condyles was measured.

Results: Measurement of the AT by 3D reconstruction (0.8°) was significantly better than the conventional method (3.0°; P = 0.016). The positioning of the femur influences measurement of the femoral AT angle by conventional method measurement, whereas evaluation using the 3D reconstruction was more independent of femoral positioning.

Conclusion: 3D reconstruction enables precise determination of the femoral AT angle, and is not dependent on femoral positioning as conventional methods are. In clinical practice, 3D reconstruction may allow an accurate understanding of femoral AT angle after fracture reduction and internal fixation. A limiting factor to incorporating this technique into standard practice may be the additional time required for its case integration.

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.