Clinical Orthopaedics and Related Research®

, Volume 471, Issue 7, pp 2173–2182

Symptomatic Femoroacetabular Impingement: Does the Offset Decrease Correlate With Cartilage Damage? A Pilot Study

  • Christoph Zilkens
  • Falk Miese
  • Rüdiger Krauspe
  • Bernd Bittersohl
Symposium: Slipped Capital Femoral Epiphysis: Update and Emerging Concepts

DOI: 10.1007/s11999-013-2812-2

Cite this article as:
Zilkens, C., Miese, F., Krauspe, R. et al. Clin Orthop Relat Res (2013) 471: 2173. doi:10.1007/s11999-013-2812-2

Abstract

Background

Current measures of the reduced head-neck offset such as residual deformity of slipped capital femoral epiphysis (SCFE) including the alpha angle, which measures the femoral head-neck sphericity but does not account for acetabular abnormalities, do not represent the true magnitude of the deformity and the mechanical consequences. The beta angle (angle between the femoral head-neck junction and acetabular rim) accounts for the morphology of both the acetabulum and femur and, thus, may be the more appropriate parameter for assessing SCFE deformity.

Questions/purposes

We determined (1) whether the beta angle could be reliably measured on MRI; and (2) whether the beta angle correlates with the cartilage status.

Methods

We recruited 10 adult patients (mean age, 28 years) with symptomatic cam femoroacetabular impingement and 15 asymptomatic volunteers (mean age, 24 years) to have three-dimensional MRI including delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) for cartilage status assessment. Corresponding alpha angles, beta angles, and acetabular dGEMRIC indices were obtained in seven radial reformats to assess the hip in seven regions (anterior to superior and posterior).

Results

We noted high reproducibility for both alpha and beta angle measurements. The dGEMRIC indices correlated with beta angles in the superoinferior and superior regions but not the alpha angles.

Conclusions

Beta angle measurement in radial MR images is reproducible and appears to correspond to cartilage damage in the superior regions of the hip. The beta angle may be a useful parameter to assess hip deformity in the followup of SCFE although further confirmation is warranted.

Copyright information

© The Association of Bone and Joint Surgeons® 2013

Authors and Affiliations

  • Christoph Zilkens
    • 1
  • Falk Miese
    • 2
  • Rüdiger Krauspe
    • 1
  • Bernd Bittersohl
    • 1
  1. 1.Medical Faculty, Department of Orthopedic SurgeryUniversity of DüsseldorfDüsseldorfGermany
  2. 2.Medical Faculty, Department of Diagnostic and Interventional RadiologyUniversity of DüsseldorfDüsseldorfGermany

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