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Using a numerical method to precisely evaluate the alpha angle in a hip image

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Abstract

The alpha angle is a parameter extensively used to assess for cam-type femoroacetabular impingement (FAI) in a 2D image of the hip. As this angle requires estimation of the axis of the femoral neck, the drawing of this axis often results in measurement errors due to subjective judgment, influencing inter-rater and intra-rater agreements. In the present study, sampling points were captured from the edges of a femoral neck and head in the 2D image, and the best curves of the two were fitted respectively by using the curve fitting method. The morphology of the femoral neck was outlined by two polynomials, and the femoral head was represented by an equation of a circle. By means of the proposed method, the results reveal that the inter-rater ICCs in X-ray and MRI were respectively 0.905 and 0.969, and the intra-rater ICCs in X-ray and MRI were respectively 0.892 and 0.840. The Bland-Altman plot shows that the values obtained by the proposed method and the conventional method were not consistent; nevertheless, the linear regression analysis indicated the two measurement results had a significant association (p < 0.001). This study provides a repeatable and agreed α angle measuring method, which contributes to identifying normal and abnormal femoral head-neck morphologies. The proposed numerical method would contribute to diagnose early FAI.

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References

  1. Anđelković Z, Mladenović D (2013) Measuring the osteochondral connection of the femoral head and neck in patients with impingement femoroacetabular by determining the angle of 2 alpha in lateral and anteroposterior hip radiographic images. Vojnosanit Pregl 70(3):259–266. https://doi.org/10.2298/VSP110727038A

    Article  Google Scholar 

  2. Anderson LA, Anderson MB, Kapron A, Aoki SK, Erickson JA, Chrastil J, Grijalva R, Peters C (2016) The 2015 Frank Stinchfield award: radiographic abnormalities common in senior athletes with well-functioning hips but not associated with osteoarthritis. Clin Orthop Relat Res 474(2):342–352. https://doi.org/10.1007/s11999-015-4379-6

    Article  PubMed  Google Scholar 

  3. Andjelković Z, Mladenović D, Vukasinović Z, Arsić S, Mitković M, Micić I, Mladenović M (2014) Contribution to the method for determining femoral neck axis. Srp Arh Celok Lek 142(3–4):178–183. https://doi.org/10.2298/sarh1404178a

    Article  PubMed  Google Scholar 

  4. Barrientos C, Barahona M, Diaz J, Brañes J, Chaparro F, Hinzpeter J (2016) Is there a pathological alpha angle for hip impingement? A diagnostic test study. J Hip Preserv Surg 3(3):223–228. https://doi.org/10.1093/jhps/hnw014

    Article  PubMed  PubMed Central  Google Scholar 

  5. Barton C, Salineros MJ, Rakhra KS, Beaule 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. https://doi.org/10.1007/s11999-010-1624-x

    Article  PubMed  Google Scholar 

  6. Bland JM, Altman DG (1986) Statisical methods for assessing agreement between two methods of clinical measurement. Lancet 327(8476):307–310. https://doi.org/10.1016/S0140-6736(86)90837-8

    Article  Google Scholar 

  7. Bonneau N, Libourel PA, Simonis C, Puymerail L, Baylac M, Tardieu C, Gagey O (2012) A three-dimensional axis for the study of femoral neck orientation. J Anat 221:465–476. https://doi.org/10.1111/j.1469-7580.2012.01565.x

    Article  PubMed  PubMed Central  Google Scholar 

  8. Bouma H, Slot NJ, Toogood P, T P, van Kampen P, Hogervorst T (2014) Where is the neck? Alpha angle measurement revisited. Acta Orthop 85(2):147–151. https://doi.org/10.3109/17453674.2014.899841

    Article  PubMed  PubMed Central  Google Scholar 

  9. Carlisle JC, Zebala LP, Shia DS, Hunt D, Morgan PM, Prather H, Wright RW, Steger-May K, Clohisy JC (2011) Reliability of various observers in determining common radiographic parameters of adult hip structural anatomy. Iowa Orthop J 31:52–58

    PubMed  PubMed Central  Google Scholar 

  10. Clohisy JC, Carlisle JC, Beaule 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. https://doi.org/10.2106/JBJS.H.00756

    Article  PubMed  PubMed Central  Google Scholar 

  11. Clohisy JC, Carlisle JC, Trousdale R, Kim YJ, Beaule PE, Morgan P, Steger-May K, Schoenecker PL, Millis M (2009) Radiographic evaluation of the hip has limited reliability. Clin Orthop Relat Res 467(3):666–675. https://doi.org/10.1007/s11999-008-0626-4

    Article  PubMed  Google Scholar 

  12. Cobb J, Logishetty K, Davda K, Iranpour F (2010) Cams and pincer impingement are distinct, not mixed: the acetabular pathomorphology of femoroacetabular impingement. Clin Orthop Relat Res 468(8):2143–2151. https://doi.org/10.1007/s11999-010-1347-z

    Article  PubMed  PubMed Central  Google Scholar 

  13. Cooper RJ, Mengoni M, Groves D, Williams S, Bankes MJK, Robinson P, Jones AC (2017) Three-dimensional assessment of impingement risk in geometrically parameterised hips compared with clinical measures. Int J Numer Method Biomed Eng 33(11):e2867. https://doi.org/10.1002/cnm.2867

    Article  PubMed Central  Google Scholar 

  14. Ecker TM, Tannast M, Puls M, Siebenrock KA, Murphy SB (2007) Pathomorphologic alterations predict presence or absence of hip osteoarthrosis. Clin Orthop Relat Res 465:46–52. https://doi.org/10.1097/BLO.0b013e318159a998

    Article  PubMed  Google Scholar 

  15. Ergen FB, Vudalı S, Şanverdi E, Dolgun A, Aydıngöz Ü (2014) CT assessment of asymptomatic hip joints for the background of femoroacetabular impingement morphology. Diagn Interv Radiol 20(3):271–276. https://doi.org/10.5152/dir.2013.13374

    Article  PubMed  Google Scholar 

  16. Fitzgibbon A, Pilu M, Fisher RB (1999) Direct least square fitting of ellipses. IEEE Trans Pattern Anal Mach Intell 21(5):476–480. https://doi.org/10.1109/34.765658

    Article  Google Scholar 

  17. Gosvig KK, Jacobsen S, Palm H, Sonne-Holm S, Magnusson E (2007) A new radiological index for assessing asphericity of the femoral head in cam impingement. J Bone Joint Surg Br 89(10):1309–1316. https://doi.org/10.1302/0301-620X.89B10.19405

    Article  CAS  PubMed  Google Scholar 

  18. Harris MD, Kapron AL, Peters CL, Anderson AE (2014) Correlations between the alpha angle and femoral head asphericity: implications and recommendations for the diagnosis of cam femoroacetabular impingement. Eur J Radiol 83(5):788–796. https://doi.org/10.1016/j.ejrad.2014.02.005

    Article  PubMed  PubMed Central  Google Scholar 

  19. Kang ACL, Gooding AJ, Coates MH, Goh TD, Armour P, Rietveld J (2010) Computed tomography assessment of hip joints in asymptomatic individuals in relation to femoroacetabular impingement. Am J Sports Med 38(6):1160–1165. https://doi.org/10.1177/0363546509358320

    Article  PubMed  Google Scholar 

  20. Kaplan KM, Shah MR, Youm T (2010) Femoroacetabular impingement: diagnosis and treatment. Bull NYU Hosp Jt Dis 68(2):70–75

    PubMed  Google Scholar 

  21. Koo TK, Li MY (2016) A guideline of selecting and reporting intraclass correlation coefficients for reliability research. J Chiropr Med 15(2):155–163. https://doi.org/10.1016/j.jcm.2016.02.012

    Article  PubMed  PubMed Central  Google Scholar 

  22. Landau UM (1987) Estimation of a circular arc center and its radius. Comput Vis Graph Image Process 38(3):317–326

    Article  Google Scholar 

  23. Levy DM, Hellman MD, Harris JD, Haughom B, Frank RM, Nho SJ (2015) Prevalence of cam morphology in females with femoroacetabular impingement. Front Surg 2:61. https://doi.org/10.3389/fsurg.2015.00061

    Article  PubMed  PubMed Central  Google Scholar 

  24. Mineta K, Goto T, Wada K, Tamaki Y, Hamada D, Tonogai I, Higashino K, Sairyo K (2016) CT-based morphological assessment of the hip joint in Japanese patients. Bone Joint J 98-B(9):1167–1174. https://doi.org/10.1302/0301-620X.98B9

    Article  CAS  PubMed  Google Scholar 

  25. Mose K (1980) Methods of measuring in Legg-Calvé-Perthes disease with special regard to the prognosis. Clin Orthop Relat Res 150:103–109

    Google Scholar 

  26. 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. https://doi.org/10.1302/0301-620X.84B4.12014

    Article  PubMed  Google Scholar 

  27. Nouh MR, Schweitzer ME, Rybak L, Cohen J (2008) Femoroacetabular impingement: can the alpha angle be estimated? AJR Am J Roentgenol 190(5):1260–1262. https://doi.org/10.2214/AJR.07.3258

    Article  PubMed  Google Scholar 

  28. Rakhra KS, Sheikh AM, Allen D, Beaule PE (2009) Comparison of MRI alpha angle measurement planes in femoroacetabular impingement. Clin Orthop Relat Res 467(3):660–665. https://doi.org/10.1007/s11999-008-0627-3

    Article  PubMed  Google Scholar 

  29. Ratzlaff C, Zhang C, Korzan J, Josey L, Wong H, Cibere J, Prlic HM, Kopec JA, Esdaile JM, Li LC, Barber M, Forster BB (2016) The validity of a non-radiologist reader in identifying cam and pincer femoroacetabular impingement (FAI) using plain radiography. Rheumatol Int 36(3):371–376. https://doi.org/10.1007/s00296-015-3361-7

    Article  CAS  PubMed  Google Scholar 

  30. Reichenbach S, Juni P, Nuesch E, Frey F, Ganz R, Leunig M (2010) An examination chair to measure internal rotation of the hip in routine settings: a validation study. Osteoarthr Cartil 18(3):365–371. https://doi.org/10.1016/j.joca.2009.10.001

    Article  CAS  PubMed  Google Scholar 

  31. Reichenbach S, Juni P, Werlen S, Nuesch E, Pfirrmann CW, Trelle S, Odermatt A, Hofstetter W, Ganz R, Leunig M (2010) Prevalence of cam-type deformity on hip magnetic resonance imaging in young males: a cross-sectional study. Arthritis Care Res (Hoboken) 62(9):1319–1327. https://doi.org/10.1002/acr.20198

    Article  Google Scholar 

  32. Saito M, Tsukada S, Yoshida K, Okada Y, Tasaki A (2017) Correlation of alpha angle between various radiographic projections and radial magnetic resonance imaging for cam deformity in femoral head-neck junction. Knee Surg Sports Traumatol Arthrosc 25(1):77–83. https://doi.org/10.1007/s00167-016-4046-9

    Article  PubMed  Google Scholar 

  33. Shang XL, Zhang JW, Chen JW, Li YX, Chen SY (2013) Features of acetabular labral tears on X-ray, magnetic resonance imaging and hip arthroscopy–the observational pilot study. Arch Med Sci 9(2):297–302. https://doi.org/10.5114/aoms.2012.31305

    Article  PubMed  Google Scholar 

  34. Sutter R, Dietrich TJ, Zingg PO, Pfirrmann CWA (2012) How useful is the alpha angle for discriminating between symptomatic patients with cam-type femoroacetabular impingement and asymptomatic volunteers? Radiology 264(2):514–521. https://doi.org/10.1148/radiol.12112479

    Article  PubMed  Google Scholar 

  35. Takeyama A, Naito M, Shiramizu K, Kiyama T (2009) Prevalence of femoroacetabular impingement in Asian patients with osteoarthritis of the hip. Int Orthop 33(5):1229–1232. https://doi.org/10.1007/s00264-009-0742-0

    Article  PubMed  PubMed Central  Google Scholar 

  36. Xia Y, Fripp J, Chandra SS, Walker D, Crozier S, Engstrom C (2015) Automated 3D quantitative assessment and measurement of alpha angles from the femoral head-neck junction using MR imaging. Phys Med Biol 60(19):7601–7616. https://doi.org/10.1088/0031-9155/60/19/7601

    Article  CAS  PubMed  Google Scholar 

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Acknowledgments

We would like to show our gratitude to all the people who greatly assisted the research, and we also thank three anonymous reviewers for their comments.

Funding

This research project was supported by the Ministry of Science and Technology of the Republic of China, Taiwan, under Contract No. MOST104-2221-E-040-002-MY2.

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Author notes

  1. Chien-Chung Lin, Wei-Min Chi, and Chung-Liang Lai contributed equally to this work (co-first author).

Authors and Affiliations

  1. Department of Occupational Therapy, Asia University, Taichung, Taiwan, Republic of China

    Chung-Liang Lai

  2. Department of Physical Medicine and Rehabilitation, Taichung Hospital, Ministry of Health and Welfare, Taichung, Taiwan, Republic of China

    Chung-Liang Lai

  3. College of Mechanical and Automotive Engineering, Zhaoqing University, Zhaoqing, Guangdong Province, China

    Wei-Min Chi

  4. Department of Psychology, Chung Shan Medical University, Taichung, Taiwan, Republic of China

    Ying-Jui Ho

  5. Orthopedic Department, Taichung Armed Forces General Hospital, Taichung, Taiwan, Republic of China

    Chien-Chung Lin

  6. Department of Orthopedic Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, Republic of China

    Chien-Chung Lin

  7. Central Region Campus, Industrial Technology Research Institute, Nantou, Taiwan, Republic of China

    Hsiao-Che Lin

  8. School of Physical Therapy, Chung Shan Medical University, No. 110, Sec. 1, Jianguo N. Rd., Taichung, 402, Taiwan, Republic of China

    Chin-Liang Kuo & Jian-Horng Chen

  9. Department of Orthopedics, Chung Shan Medical University Hospital, Taiwan, Republic of China

    Jian-Horng Chen

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  1. Chung-Liang Lai
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Lai, CL., Chi, WM., Ho, YJ. et al. Using a numerical method to precisely evaluate the alpha angle in a hip image. Med Biol Eng Comput 57, 1525–1535 (2019). https://doi.org/10.1007/s11517-019-01973-4

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