Skip to main content
Log in

Experimental study of an original radiographic view for diagnosis of cam-type anterior femoroacetabular impingement

  • Original Paper
  • Published:
International Orthopaedics Aims and scope Submit manuscript



Primary paraclinical investigation to look for femoral morphological abnormality consistent with cam-type anterior femoroacetabular impingement (FAI) must include specific radiographic projections of the hip from the following: cross-table, frog-leg or Dunn (90° and 45° flexion). We use a frog-leg type view with fixed angles as described by Chiron, obtained with the patient in a supine position, with the hip in 45° flexion-abduction and 30° external rotation. The X-ray beam is anteroposterior and centred on the femoral head. We evaluated this view by comparing it with other views in common use.


In this experimental study, we created artificial radio-opaque morphological abnormalities secured onto normal femoral necks. The femurs were placed in relation to a fixed pelvis using orthogonal landmarks, in the positions of the various radiographic views. The digital radiographs were analysed by two observers. Nineteen femurs were included to reveal a difference of 5° between the alpha angle of Nötzli et al. [11] measured on the Dunn view and the frog-leg 45/45/30 view (Student’s paired test).


The highest mean values of the alpha angle of Nötzli were always obtained with the frog-leg 45/45/30 view (87.4°, 86.2°, 84.5°) and the lowest with the cross-table view. We found a mean difference of 8.95° with the 90° Dunn view (P = 0.00007), 3.44° with the 45° Dunn view (P = 0.004) and 13.47° with the cross-table view (P = 0.002).


This experimental study confirmed the value of the frog-leg 45/45/30 view in assisting diagnosis of cam-type FAI.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Subscribe and save

Springer+ Basic
EUR 32.99 /Month
  • Get 10 units per month
  • Download Article/Chapter or Ebook
  • 1 Unit = 1 Article or 1 Chapter
  • Cancel anytime
Subscribe now

Buy Now

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5

Similar content being viewed by others


  1. Ganz R, Parvizi J, Beck M, Leunig M, Nötzli H, Siebenrock KA (2003) Femoroacetabular impingement: a cause for osteoarthritis of the hip. Clin Orthop Relat Res 417:112–120

    PubMed  Google Scholar 

  2. Imam S, Khanduja V (2011) Current concepts in the diagnosis and management of femoroacetabular impingement. Int Orthop 35(10):1427–1435

    Article  PubMed  Google Scholar 

  3. Hack K, Di Primio G, Rakhra K, Beaulé PE (2010) Prevalence of cam-type femoroacetabular impingement morphology in asymptomatic volunteers. J Bone Joint Surg Am 92(14):2436–2444

    Article  PubMed  Google Scholar 

  4. Beaulé PE, Zaragoza E, Motamedi K, Copelan N, Dorey FJ (2005) Three-dimensional computed tomography of the hip in the assessment of femoroacetabular impingement. J Orthop Res 23(6):1286–1292

    PubMed  Google Scholar 

  5. Ito K, Minka MA 2nd, Leunig M, Werlen S, Ganz R (2001) Femoroacetabular impingement and the cam-effect. A MRI-based quantitative anatomical study of the femoral head-neck offset. J Bone Joint Surg Br 83(2):171–176

    Article  PubMed  CAS  Google Scholar 

  6. Clohisy JC, Beaulé PE, O'Malley A, Safran MR, Schoenecker P (2008) AOA symposium. Hip disease in the young adult: current concepts of etiology and surgical treatment. J Bone Joint Surg Am 90(10):2267–2281

    Article  PubMed  Google Scholar 

  7. Clohisy JC, Carlisle JC, Beaulé PE, Kim YJ, Trousdale RT, Sierra RJ, Leunig M, Schoenecker PL, Millis MB (2008) A systematic approach to the plain radiographic evaluation of the young adult hip. J Bone Joint Surg Am 90(Suppl 4):47–66

    Article  PubMed  Google Scholar 

  8. Dunn DM (1952) Anteversion of the neck of the femur; a method of measurement. J Bone Joint Surg Br 34-B(2):181–186

    PubMed  CAS  Google Scholar 

  9. Meyer DC, Beck M, Ellis T, Ganz R, Leunig M (2006) Comparison of six radiographic projections to assess femoral head/neck asphericity. Clin Orthop Relat Res 445:181–185

    PubMed  Google Scholar 

  10. Kutty S, Schneider P, Faris P, Kiefer G, Frizzell B, Park R, Powell JN (2012) Reliability and predictability of the centre-edge angle in the assessment of pincer femoroacetabular impingement. Int Orthop 36(3):505–510

    Article  PubMed  Google Scholar 

  11. Nötzli HP, Wyss TF, Stoecklin CH, Schmid MR, Treiber K, Hodler J (2002) The contour of the femoral head-neck junction as a predictor for the risk of anterior impingement. J Bone Joint Surg Br 84(4):556–560

    Article  PubMed  Google Scholar 

  12. Barton C, Salineros MJ, Rakhra KS, Beaulé PE (2011) Validity of the alpha angle measurement on plain radiographs in the evaluation of cam-type femoroacetabular impingement. Clin Orthop Relat Res 469(2):464–469

    Article  PubMed  Google Scholar 

  13. Chiron P, Laffosse JM (2008) Les lésions du labrum de la hanche: signes, imagerie, traitement. Rev Rhum 76(2):202–207

    Article  Google Scholar 

  14. Rosset A, Spadola L, Ratib O (2004) OsiriX: an open-source software for navigating in multidimensional DICOM images. J Digit Imaging 17(3):205–216

    Article  PubMed  Google Scholar 

  15. Tannast M, Goricki D, Beck M, Murphy SB, Siebenrock KA (2008) Hip damage occurs at the zone of femoroacetabular impingement. Clin Orthop Relat Res 466(2):273–280

    Article  PubMed  CAS  Google Scholar 

  16. Clohisy JC, Nunley RM, Otto RJ, Schoenecker PL (2007) The frog-leg lateral radiograph accurately visualized hip cam impingement abnormalities. Clin Orthop Relat Res 462:115–121

    Article  PubMed  Google Scholar 

  17. Konan S, Rayan F, Haddad FS (2010) Is the frog lateral plain radiograph a reliable predictor of the alpha angle in femoroacetabular impingement? J Bone Joint Surg Br 92(1):47–50

    Article  PubMed  CAS  Google Scholar 

  18. Chiron P, Espié A, Reina N, Cavaignac E, Molinier F, Laffosse JM (2012) Surgery for femoroacetabular impingement using a minimally invasive anterolateral approach: Analysis of 118 cases at 2.2-year follow-up. Orthop Traumatol Surg Res 98(1):30–38

    Article  PubMed  CAS  Google Scholar 

Download references

Author information

Authors and Affiliations


Corresponding author

Correspondence to Etienne Cavaignac.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Cavaignac, E., Chiron, P., Espié, A. et al. Experimental study of an original radiographic view for diagnosis of cam-type anterior femoroacetabular impingement. International Orthopaedics (SICOT) 36, 1783–1788 (2012).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: