Clinical Orthopaedics and Related Research®

, Volume 471, Issue 8, pp 2578–2585

Reliability of Overcoverage Parameters With Varying Morphologic Pincer Features: Comparison of EOS® and Radiography

  • Shafagh Monazzam
  • Mandar Agashe
  • Harish S. Hosalkar
Basic Research



Multiple radiographic parameters used for diagnosis and quantification of morphologic pincer features have emerged, but the degree to which pelvic tilt or rotation affects conventional radiography and EOS® is unknown.


We asked: (1) What is the reliability of EOS® and conventional radiography at increasing sizes of morphologic pincer features with varying degrees of tilt and rotation? (2) What is the effect of tilt and rotation on acetabular overcoverage measurements?


Using a dry cadaveric pelvis, AP conventional radiographs and EOS® images were taken at intervals of increasing modeled pincer size with 0° to 15° varying tilt and rotation. Lateral center-edge angle, Sharp angle, Tönnis angle, crossover sign, and retroversion index were measured on all images. Statistical analysis was conducted.


The intermodality intraclass correlation coefficients for conventional radiography and EOS® radiography across all pincer sizes, rotations, and tilts were excellent (0.93–0.98). Crossover sign was in perfect agreement in conventional radiography and EOS®. Rotation of the hip away from the beam source and/or increased anterior tilt falsely increased all overcoverage parameters except for Tönnis angle. Rotation away from the beam of 10°or greater or anterior tilt of 5° or greater produced a false-positive crossover sign.


EOS® radiography maintained excellent reliability in comparison to conventional radiography but both were equally vulnerable to the effects of tilt and rotation for quantification of hip parameters used in acetabular overcoverage assessment. A standardized pelvic radiograph ensuring that the pelvis is not excessively tilted or rotated should be used for assessing acetabular overcoverage parameters.


  1. 1.
    Azmy C, Guerard S, Bonnet X, Gabrielli F, Skalli W. EOS orthopaedic imaging system to study patellofemoral kinematics: assessment of uncertainty. Orthop Traumatol Surg Res. 2010;96:28–36.PubMedCrossRefGoogle Scholar
  2. 2.
    Bell AL, Brand RA. Roentgenographic changes in proximal femoral dimensions due to hip rotation. Clin Orthop Relat Res. 1989;240:194–199.PubMedGoogle Scholar
  3. 3.
    Bushberg JT. The Essential Physics of Medical Imaging. Philadelphia, PA: Lippincott Williams & Wilkins; 2002.Google Scholar
  4. 4.
    Clohisy JC, Carlisle JC, Beaule PE, Kim YJ, Trousdale RT, Sierra RJ, Leunig M, Schoenecker PL, Millis MB. A systematic approach to the plain radiographic evaluation of the young adult hip. J Bone Joint Surg Am. 2008;90(suppl 4):47–66.PubMedCrossRefGoogle Scholar
  5. 5.
    Dandachli W, Najefi A, Iranpour F, Lenihan J, Hart A, Cobb J. Quantifying the contribution of pincer deformity to femoro-acetabular impingement using 3D computerised tomography. Skeletal Radiol. 2012;41:1295–1300.PubMedCrossRefGoogle Scholar
  6. 6.
    Deschenes S, Charron G, Beaudoin G, Labelle H, Dubois J, Miron MC, Parent S. Diagnostic imaging of spinal deformities: reducing patients radiation dose with a new slot-scanning X-ray imager. Spine (Phila Pa 1976). 2010;35:989–994.Google Scholar
  7. 7.
    Dolan MM, Heyworth BE, Bedi A, Duke G, Kelly BT. CT reveals a high incidence of osseous abnormalities in hips with labral tears. Clin Orthop Relat Res. 2011;469:831–838.PubMedCrossRefGoogle Scholar
  8. 8.
    Dubousset J, Charpak G, Dorion I, Skalli W, Lavaste F, Deguise J, Kalifa G, Ferey S. [A new 2D and 3D imaging approach to musculoskeletal physiology and pathology with low-dose radiation and the standing position: the EOS system][in French]. Bull Acad Natl Med. 2005;189:287–297; discussion 297–300.PubMedGoogle Scholar
  9. 9.
    Ganz R, Leunig M, Leunig-Ganz K, Harris WH. The etiology of osteoarthritis of the hip: an integrated mechanical concept. Clin Orthop Relat Res. 2008;466:264–272.PubMedCrossRefGoogle Scholar
  10. 10.
    Ganz R, Parvizi J, Beck M, Leunig M, Notzli H, Siebenrock KA. Femoroacetabular impingement: a cause for osteoarthritis of the hip. Clin Orthop Relat Res. 2003;417:112–120.PubMedGoogle Scholar
  11. 11.
    Hananouchi T, Sugano N, Nakamura N, Nishii T, Miki H, Yamamura M, Yoshikawa H. Preoperative templating of femoral components on plain X-rays: rotational evaluation with synthetic X-rays on ORTHODOC. Arch Orthop Trauma Surg. 2007;127:381–385.PubMedCrossRefGoogle Scholar
  12. 12.
    Hoan NN, Majewski S, Charpak G, Policarpo AJ. An efficient, gaseous detector with good low-energy resolution for (less than or equal to 50 keV) imaging. J Nucl Med. 1979;20:335–340.PubMedGoogle Scholar
  13. 13.
    Ito K, Minka MA 2nd, Leunig M, Werlen S, Ganz R. Femoroacetabular impingement and the cam-effect: a MRI-based quantitative anatomical study of the femoral head-neck offset. J Bone Joint Surg Br. 2001;83:171–176.PubMedCrossRefGoogle Scholar
  14. 14.
    Jacobsen S, Sonne-Holm S, Lund B, Soballe K, Kiaer T, Rovsing H, Monrad H. Pelvic orientation and assessment of hip dysplasia in adults. Acta Orthop Scand. 2004;75:721–729.PubMedCrossRefGoogle Scholar
  15. 15.
    Kalifa G, Charpak Y, Maccia C, Fery-Lemonnier E, Bloch J, Boussard JM, Attal M, Dubousset J, Adamsbaum C. Evaluation of a new low-dose digital x-ray device: first dosimetric and clinical results in children. Pediatr Radiol. 1998;28:557–561.PubMedCrossRefGoogle Scholar
  16. 16.
    Kutty S, Schneider P, Faris P, Kiefer G, Frizzell B, Park R, Powell JN. Reliability and predictability of the centre-edge angle in the assessment of pincer femoroacetabular impingement. Int Orthop. 2012;36:505–510.PubMedCrossRefGoogle Scholar
  17. 17.
    Lazennec JY, Rangel A, Baudoin A, Skalli W, Catonne Y, Rousseau MA. The EOS imaging system for understanding a patellofemoral disorder following THR. Orthop Traumatol Surg Res. 2011;97:98–101.PubMedCrossRefGoogle Scholar
  18. 18.
    Lazennec JY, Rousseau MA, Rangel A, Gorin M, Belicourt C, Brusson A, Catonne Y. Pelvis and total hip arthroplasty acetabular component orientations in sitting and standing positions: measurements reproductibility with EOS imaging system versus conventional radiographies. Orthop Traumatol Surg Res. 2011;97:373–380.PubMedCrossRefGoogle Scholar
  19. 19.
    Linclau L, Dokter G, Peene P. Radiological aspects in preoperative planning and postoperative assessment of cementless total hip arthroplasty. Acta Orthop Belg. 1993;59:163–167.PubMedGoogle Scholar
  20. 20.
    McKenna C, Wade R, Faria R, Yang H, Stirk L, Gummerson N, Sculpher M, Woolacott N. EOS 2D/3D X-ray imaging system: a systematic review and economic evaluation. Health Technol Assess. 2012;16:1–188.Google Scholar
  21. 21.
    Ochoa LM, Dawson L, Patzkowski JC, Hsu JR. Radiographic prevalence of femoroacetabular impingement in a young population with hip complaints is high. Clin Orthop Relat Res. 2010;468:2710–2714.PubMedCrossRefGoogle Scholar
  22. 22.
    Philippon MJ, Wolff AB, Briggs KK, Zehms CT, Kuppersmith DA. Acetabular rim reduction for the treatment of femoroacetabular impingement correlates with preoperative and postoperative center-edge angle. Arthroscopy. 2010;26:757–761.PubMedCrossRefGoogle Scholar
  23. 23.
    Reynolds D, Lucas J, Klaue K. Retroversion of the acetabulum: a cause of hip pain. J Bone Joint Surg Br. 1999;81:281–288.PubMedCrossRefGoogle Scholar
  24. 24.
    Schlatterer B, Suedhoff I, Bonnet X, Catonne Y, Maestro M, Skalli W. Skeletal landmarks for TKR implantations: evaluation of their accuracy using EOS imaging acquisition system. Orthop Traumatol Surg Res. 2009;95:2–11.PubMedCrossRefGoogle Scholar
  25. 25.
    Sharp IK. Acetabular dysplasia: the acetabular angle. J Bone Joint Surg Br. 1961;43:268–272.Google Scholar
  26. 26.
    Siebenrock KA, Kalbermatten DF, Ganz R. Effect of pelvic tilt on acetabular retroversion: a study of pelves from cadavers. Clin Orthop Relat Res. 2003;407:241–248.PubMedCrossRefGoogle Scholar
  27. 27.
    Siebenrock KA, Schoeniger R, Ganz R. Anterior femoro-acetabular impingement due to acetabular retroversion: treatment with periacetabular osteotomy. J Bone Joint Surg Am. 2003;85:278–286.PubMedGoogle Scholar
  28. 28.
    Tannast M, Mistry S, Steppacher SD, Reichenbach S, Langlotz F, Siebenrock KA, Zheng G. Radiographic analysis of femoroacetabular impingement with Hip2Norm-reliable and validated. J Orthop Res. 2008;26:1199–1205.PubMedCrossRefGoogle Scholar
  29. 29.
    Tannast M, Siebenrock KA, Anderson SE. Femoroacetabular impingement: radiographic diagnosis—what the radiologist should know. AJR Am J Roentgenol. 2007;188:1540–1552.PubMedCrossRefGoogle Scholar
  30. 30.
    Tannast M, Zheng G, Anderegg C, Burckhardt K, Langlotz F, Ganz R, Siebenrock KA. Tilt and rotation correction of acetabular version on pelvic radiographs. Clin Orthop Relat Res. 2005;438:182–190.PubMedCrossRefGoogle Scholar
  31. 31.
    Than P, Szuper K, Somoskeoy S, Warta V, Illes T. Geometrical values of the normal and arthritic hip and knee detected with the EOS imaging system. Int Orthop. 2012;36:1291–1297.PubMedCrossRefGoogle Scholar
  32. 32.
    Tönnis D. Congenital Dysplasia and Dislocation of the Hip in Children and Adults. Berlin, Germany: Springer-Verlag; 1987.CrossRefGoogle Scholar
  33. 33.
    Toogood PA, Skalak A, Cooperman DR. Proximal femoral anatomy in the normal human population. Clin Orthop Relat Res. 2009;467:876–885.PubMedCrossRefGoogle Scholar
  34. 34.
    Wassilew GI, Heller MO, Diederichs G, Janz V, Wenzl M, Perka C. Standardized AP radiographs do not provide reliable diagnostic measures for the assessment of acetabular retroversion. J Orthop Res. 2012;30:1369–1376.PubMedCrossRefGoogle Scholar
  35. 35.
    Wiberg G. Studies on dysplastic acetabula and congenital subluxation of the hip joint: with special referance to the complication of osteoarthritis. Acta Chir Scand Suppl. 1939;83(suppl 58):1–135.Google Scholar

Copyright information

© The Association of Bone and Joint Surgeons® 2013

Authors and Affiliations

  • Shafagh Monazzam
    • 1
  • Mandar Agashe
    • 2
  • Harish S. Hosalkar
    • 1
  1. 1.Center for Hip Preservation and Children’s OrthopaedicsSan DiegoUSA
  2. 2.Dr Agashe HospitalMumbaiIndia

Personalised recommendations