The Journal of Bone and Joint Surgery (American). 2009;91:2598-2604.
doi:10.2106/JBJS.H.01225
© 2009 The Journal of Bone and Joint Surgery, Inc.
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A Comparison of Surgeon Estimation and Computed Tomographic Measurement of Femoral Component Anteversion in Cementless Total Hip Arthroplasty

Lawrence D. Dorr, MD1, Zhinian Wan, MD1, Aamer Malik, MD1, Jinjun Zhu, MD1, Manish Dastane, MD1 and Prashant Deshmane, MD1

1 The Arthritis Institute at Good Samaritan Hospital, 637 South Lucas Avenue, 5th Floor, Los Angeles, CA 90017. E-mail address for L.D. Dorr: Patriciajpaul{at}yahoo.com

Investigation performed at The Arthritis Institute at Good Samaritan Hospital, Los Angeles, California

Disclosure: In support of their research for or preparation of this work, one or more of the authors received, in any one year, outside funding or grants in excess of $10,000 from Good Samaritan Hospital, Los Angeles, California. Neither they nor a member of their immediate families received 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, division, center, clinical practice, or other charitable or nonprofit organization with which the authors, or a member of their immediate families, are affiliated or associated.

Background: The intraoperative estimation of the anteversion of the femoral component of a total hip arthroplasty is generally made by the surgeon's visual assessment of the stem position relative to the condylar plane of the femur. Although the generally accepted range of intended anteversion is between 10° and 20°, we suspected that achieving this range of anteversion consistently during cementless implantation of the femoral component was more difficult than previously thought.

Methods: We prospectively evaluated the accuracy of femoral component anteversion in 109 consecutive total hip arthroplasties (ninety-nine patients), in which we implanted the femoral component without cement. In all hips, we measured femoral stem anteversion postoperatively with three-dimensional computed tomography reconstruction of the femur, using both the distal femoral epicondyles and the posterior femoral condyles to determine the femoral diaphyseal plane. The bias and precision of the measurements were calculated.

Results: The surgeon's estimate of femoral stem anteversion was a mean (and standard deviation) of 9.6° ± 7.2° (range, –8° to 28°). The anteversion of the stem measured by computed tomography was a mean of 10.2° ± 7.5 ° (range, –8.6° to 27.1°) (p = 0.324). The correlation coefficient between the surgeon's estimate and the computed tomographic measurement was 0.688; the intraclass coefficient was 0.801. Anteversion measured by computed tomography found that forty-nine stems (45%) were between 10° and 20° of anteversion; forty-three stems (39%) were between 0° and 9° of femoral anteversion; eight stems (7%) were in anteversion of >20°; and nine stems (8%) were in retroversion.

Conclusions: The surgeon's estimation of the anteversion of the cementless femoral stem has poor precision and is often not within the intended range of 10° to 20° of anteversion. The implications of this finding increase the importance of achieving a safe range of motion by evaluating the combined anteversion of the stem and the cup.

Level of Evidence: Diagnostic Level I. See Instructions to Authors for a complete description of levels of evidence.


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