J Shoulder Elbow Surg (2013) -, 1-6
www.elsevier.com/locate/ymse
Relationship of individual scapular anatomy and degenerative rotator cuff tears Beat K. Moor, MDa,b,*, Karl Wieser, MDa, Ksenija Slankamenac, MD, PhDc, Christian Gerber, MDa, Samy Bouaicha, MDc a
Department of Orthopaedics, Balgrist University Hospital, Z€urich, Switzerland Department of Orthopaedic Surgery and Traumatology, Inselspital, Bern University Hospital, Bern, Switzerland c Division of Trauma Surgery, University Hospital of Zurich, Z€urich, Switzerland b
Background: The etiology of rotator cuff disease is age related, as documented by prevalence data. Despite conflicting results, growing evidence suggests that distinct scapular morphologies may accelerate the underlying degenerative process. The purpose of the present study was to evaluate the predictive power of 5 commonly used radiologic parameters of scapular morphology to discriminate between patients with intact rotator cuff tendons and those with torn rotator cuff tendons. Methods: A pre hoc power analysis was performed to determine the sample size. Two independent readers measured the acromion index, lateral acromion angle, and critical shoulder angle on standardized anteroposterior radiographs. In addition, the acromial morphology according to Bigliani and the acromial slope were determined on true outlet views. Measurements were performed in 51 consecutive patients with documented degenerative rotator cuff tears and in an age- and sex-matched control group of 51 patients with intact rotator cuff tendons. Receiver operating characteristic analyses were performed to determine cutoff values and to assess the sensitivity and specificity of each parameter. Results: Patients with degenerative rotator cuff tears demonstrated significantly higher acromion indices, smaller lateral acromion angles, and larger critical shoulder angles than patients with intact rotator cuffs. However, no difference was found between the acromial morphology according to Bigliani and the acromial slope. With an area under the receiver operating characteristic curve of 0.855 and an odds ratio of 10.8, the critical shoulder angle represented the strongest predictor for the presence of a rotator cuff tear. Conclusion: The acromion index, lateral acromion angle, and critical shoulder angle accurately predict the presence of degenerative rotator cuff tears. Level of evidence: Level IV, Case-Control Design, Diagnostic Study. Ó 2013 Journal of Shoulder and Elbow Surgery Board of Trustees. Keywords: Rotator cuff disease; scapular anatomy; acromial morphology; critical shoulder angle; acromion index; lateral acromion angle; acromial slope
Funding: This was an internally financed study. There were no external funding sources. IRB: This study was conducted at the Balgrist University Hospital, Z€urich, according to medical-ethical guidelines after informed consent was obtained from all of the individuals studied for retrospective data analysis.
*Reprint requests: Beat K. Moor, MD, Department of Orthopaedics, Balgrist University Hospital, Forchstrasse 340, CH-8008 Z€urich, Switzerland. E-mail address: [email protected] (B.K. Moor).
1058-2746/$ - see front matter Ó 2013 Journal of Shoulder and Elbow Surgery Board of Trustees. http://dx.doi.org/10.1016/j.jse.2013.11.008
2 Distinct anatomic variants of the scapula have been found to be associated with degenerative rotator cuff tears (RCTs). Neer14,15 described a bone spur at the anteroinferior acromion and attributed 95% of all RCTs to a mechanical conflict between the rotator cuff insertion and coracoacromial arch. Accordingly, Bigliani et al5 classified the shape of the acromion into 3 patterns that were more or less prone to rotator cuff disease. An increased prevalence of RCTs was then found in relation to a flatter slope of the acromion and a decreased lateral acromion angle.1,3 Other authors focused on the inclination of the glenoid and hypothesized that an upward-facing glenoid would less efficiently resist the cranial pull of the deltoid muscle and therefore favor secondary impingement.8,22 A similar concept was introduced with the acromion index.18 Nyffeler et al postulated that a large lateral extension of the acromion results in a more vertical orientation of the force vector of the middle deltoid, necessitating higher loads of the rotator cuff to maintain the humeral head centered on the glenoid. More recently, the critical shoulder angle was introduced, and a strong association between large angles and degenerative RCTs was demonstrated.12 The aims of the present study were to assess the interrater reliability of different radiologic parameters of scapular morphology and to determine their individual predictive power for the presence of degenerative rotator cuff disease. Because the critical shoulder angle represents the combination of glenoid inclination and acromial coverage, we hypothesized that this parameter is the most valuable measure to discriminate between patients with intact rotator cuff tendons and those with torn rotator cuff tendons.
Materials and methods Patient selection On the basis of data from previously published series, pre hoc power analysis was performed for each of the outcome measures.1-3,9,11,12,18,23 This analysis determined that for a significance level (type I error) of 5%, a sample size of 51 patients in each group was sufficient to provide a desired power of 95%. The RCT group consisted of 51 consecutive patients who underwent arthroscopic rotator cuff surgery between January 2012 and October 2012 for a degenerative full-thickness tear involving at least the supraspinatus tendon. RCTs were diagnosed by magnetic resonance imaging and were corroborated at surgery. Only patients with available preoperative true anteroposterior and standardized lateral (outlet) views were included.10,20 Patients with inflammatory disease or a history of trauma or previous surgery were excluded, as were those with an acromiohumeral distance 7 mm were included. Although discrete morphologic changes were possible, substantial modification of the bone anatomy by the presence of long-standing massive RCTs can be excluded. Nevertheless, the present study could not determine whether the demonstrated associations of different scapular morphologies with the presence of degenerative rotator cuff disease have a cause-effect relationship. In addition, our study group may have been subjected to selection bias, as only symptomatic shoulders were included. It is therefore possible that our findings would be different in a population of individuals with only asymptomatic RCTs.
Conclusion This study confirms the previously reported association of the AI, LAA, and CSA with the occurrence of degenerative RCTs. Of all the assessed parameters, the CSA allowed the most accurate prediction of a patient’s individual risk of experiencing a RCT. In contrast to these findings, neither the relationship between rotator cuff disease and different types of the acromion morphology according to Bigliani and Morrison nor the association of RCTs with flattened acromial slopes could be confirmed.
Disclaimer The authors, their immediate families, and any research foundation with which they are affiliated did not receive any financial payments or other benefits from any commercial entity related to the subject of this article.
5
References 1. Aoki M, Ishii S, Usui M. The slope of the acromion and rotator cuff impingement. Orthop Trans 1986;10:228. 2. Balke M, Schmidt C, Dedy N, Banerjee M, Bouillon B, Liem D. Correlation of acromial morphology with impingement syndrome and rotator cuff tears. Acta Orthop 2013;84:178-83. http://dx.doi.org/10. 3109/17453674.2013.773413 3. Banas MP, Miller RJ, Totterman S. Relationship between the lateral acromion angle and rotator cuff disease. J Shoulder Elbow Surg 1995; 4:454-61. 4. Bhatia DN, Debeer JF, Toit DF. Association of a large lateral extension of the acromion with rotator cuff tears. J Bone Joint Surg Am 2006;88:1889. 5. Bigliani L, Morrison D, April E. The morphology of the acromion and its relationship to rotator cuff tears. Orthop Trans 1986;10:216. 6. Hamada K, Fukuda H, Mikasa M, Kobayashi Y. Roentgenographic findings in massive rotator cuff tears. A long-term observation. Clin Orthop Relat Res 1990;254:92-6. 7. Hamid N, Omid R, Yamaguchi K, Steger-May K, Stobbs G, Keener JD. Relationship of radiographic acromial characteristics and rotator cuff disease: a prospective investigation of clinical, radiographic, and sonographic findings. J Shoulder Elbow Surg 2012;21: 1289-98. http://dx.doi.org/10.1016/j.jse.2011.09.028 8. Hughes RE, Bryant CR, Hall JM, Wening J, Huston LJ, Kuhn JE, et al. Glenoid inclination is associated with full-thickness rotator cuff tears. Clin Orthop Relat Res 2003;(407):86-91. 9. Kim JR, Ryu KJ, Hong IT, Kim BK, Kim JH. Can a high acromion index predict rotator cuff tears? Int Orthop 2012;36:1019-24. http://dx. doi.org/10.1007/s00264-012-1499-4 10. Liotard JP, Cochard P, Walch G. Critical analysis of the supraspinatus outlet view: rationale for a standard scapular Y-view. J Shoulder Elbow Surg 1998;7:134-9. 11. Miyazaki AN, Itoi E, Sano H, Fregoneze M, Santos PD, da Silva LA, et al. Comparison between the acromion index and rotator cuff tears in the Brazilian and Japanese populations. J Shoulder Elbow Surg 2011; 20:1082-6. http://dx.doi.org/10.1016/j.jse.2011.04.028 12. Moor BK, Bouaicha S, Rothenfluh DA, Sukthankar A, Gerber C. Is there an association between the individual anatomy of the scapula and the development of rotator cuff tears or osteoarthritis of the glenohumeral joint? A radiological study of the critical shoulder angle. Bone Joint J 2013;95-B:935-41. http://dx.doi.org/10.1302/0301-620X.95B7.31028 13. Musil D, Sadovsky P, Rost M, Stehlik J, Filip L. Relationship of acromial morphology and rotator cuff tears. Acta Chir Orthop Traumatol Cech 2012;79:238-42. 14. Neer CS 2nd. Anterior acromioplasty for the chronic impingement syndrome in the shoulder: a preliminary report. J Bone Joint Surg Am 1972;54:41-50. 15. Neer CS 2nd. Impingement lesions. Clin Orthop Relat Res 1983;173: 70-7. 16. Neer CS 2nd, Craig EV, Fukuda H. Cuff-tear arthropathy. J Bone Joint Surg Am 1983;65:1232-44. 17. Nicholson GP, Goodman DA, Flatow EL, Bigliani LU. The acromion: morphologic condition and age-related changes. A study of 420 scapulas. J Shoulder Elbow Surg 1996;5:1-11. 18. Nyffeler RW, Werner CM, Sukthankar A, Schmid MR, Gerber C. Association of a large lateral extension of the acromion with rotator cuff tears. J Bone Joint Surg Am 2006;88:800-5. http://dx.doi.org/10. 2106/JBJS.D.03042 19. Ozaki J, Fujimoto S, Nakagawa Y, Masuhara K, Tamai S. Tears of the rotator cuff of the shoulder associated with pathological changes in the acromion. A study in cadavera. J Bone Joint Surg Am 1988;70:1224-30. 20. Sanders TG, Jersey SL. Conventional radiography of the shoulder. Semin Roentgenol 2005;40:207-22. 21. Shah NN, Bayliss NC, Malcolm A. Shape of the acromion: congenital or acquiredda macroscopic, radiographic, and microscopic study of acromion. J Shoulder Elbow Surg 2001;10:309-16.
6 22. Tetreault P, Krueger A, Zurakowski D, Gerber C. Glenoid version and rotator cuff tears. J Orthop Res 2004;22:202-7. http://dx.doi.org/10. 1016/S0736-0266(03)00116-5 23. Torrens C, Lopez JM, Puente I, Caceres E. The influence of the acromial coverage index in rotator cuff tears. J Shoulder Elbow Surg 2007;16:347-51. http://dx.doi.org/10.1016/j.jse.2006.07.006
B.K. Moor et al. 24. Wang JC, Shapiro MS. Changes in acromial morphology with age. J Shoulder Elbow Surg 1997;6:55-9. 25. Zumstein MA, Jost B, Hempel J, Hodler J, Gerber C. The clinical and structural long-term results of open repair of massive tears of the rotator cuff. J Bone Joint Surg Am 2008;90:2423-31. http://dx.doi.org/ 10.2106/JBJS.G.00677
www.elsevier.com/locate/ymse
Relationship of individual scapular anatomy and degenerative rotator cuff tears Beat K. Moor, MDa,b,*, Karl Wieser, MDa, Ksenija Slankamenac, MD, PhDc, Christian Gerber, MDa, Samy Bouaicha, MDc a
Department of Orthopaedics, Balgrist University Hospital, Z€urich, Switzerland Department of Orthopaedic Surgery and Traumatology, Inselspital, Bern University Hospital, Bern, Switzerland c Division of Trauma Surgery, University Hospital of Zurich, Z€urich, Switzerland b
Background: The etiology of rotator cuff disease is age related, as documented by prevalence data. Despite conflicting results, growing evidence suggests that distinct scapular morphologies may accelerate the underlying degenerative process. The purpose of the present study was to evaluate the predictive power of 5 commonly used radiologic parameters of scapular morphology to discriminate between patients with intact rotator cuff tendons and those with torn rotator cuff tendons. Methods: A pre hoc power analysis was performed to determine the sample size. Two independent readers measured the acromion index, lateral acromion angle, and critical shoulder angle on standardized anteroposterior radiographs. In addition, the acromial morphology according to Bigliani and the acromial slope were determined on true outlet views. Measurements were performed in 51 consecutive patients with documented degenerative rotator cuff tears and in an age- and sex-matched control group of 51 patients with intact rotator cuff tendons. Receiver operating characteristic analyses were performed to determine cutoff values and to assess the sensitivity and specificity of each parameter. Results: Patients with degenerative rotator cuff tears demonstrated significantly higher acromion indices, smaller lateral acromion angles, and larger critical shoulder angles than patients with intact rotator cuffs. However, no difference was found between the acromial morphology according to Bigliani and the acromial slope. With an area under the receiver operating characteristic curve of 0.855 and an odds ratio of 10.8, the critical shoulder angle represented the strongest predictor for the presence of a rotator cuff tear. Conclusion: The acromion index, lateral acromion angle, and critical shoulder angle accurately predict the presence of degenerative rotator cuff tears. Level of evidence: Level IV, Case-Control Design, Diagnostic Study. Ó 2013 Journal of Shoulder and Elbow Surgery Board of Trustees. Keywords: Rotator cuff disease; scapular anatomy; acromial morphology; critical shoulder angle; acromion index; lateral acromion angle; acromial slope
Funding: This was an internally financed study. There were no external funding sources. IRB: This study was conducted at the Balgrist University Hospital, Z€urich, according to medical-ethical guidelines after informed consent was obtained from all of the individuals studied for retrospective data analysis.
*Reprint requests: Beat K. Moor, MD, Department of Orthopaedics, Balgrist University Hospital, Forchstrasse 340, CH-8008 Z€urich, Switzerland. E-mail address: [email protected] (B.K. Moor).
1058-2746/$ - see front matter Ó 2013 Journal of Shoulder and Elbow Surgery Board of Trustees. http://dx.doi.org/10.1016/j.jse.2013.11.008
2 Distinct anatomic variants of the scapula have been found to be associated with degenerative rotator cuff tears (RCTs). Neer14,15 described a bone spur at the anteroinferior acromion and attributed 95% of all RCTs to a mechanical conflict between the rotator cuff insertion and coracoacromial arch. Accordingly, Bigliani et al5 classified the shape of the acromion into 3 patterns that were more or less prone to rotator cuff disease. An increased prevalence of RCTs was then found in relation to a flatter slope of the acromion and a decreased lateral acromion angle.1,3 Other authors focused on the inclination of the glenoid and hypothesized that an upward-facing glenoid would less efficiently resist the cranial pull of the deltoid muscle and therefore favor secondary impingement.8,22 A similar concept was introduced with the acromion index.18 Nyffeler et al postulated that a large lateral extension of the acromion results in a more vertical orientation of the force vector of the middle deltoid, necessitating higher loads of the rotator cuff to maintain the humeral head centered on the glenoid. More recently, the critical shoulder angle was introduced, and a strong association between large angles and degenerative RCTs was demonstrated.12 The aims of the present study were to assess the interrater reliability of different radiologic parameters of scapular morphology and to determine their individual predictive power for the presence of degenerative rotator cuff disease. Because the critical shoulder angle represents the combination of glenoid inclination and acromial coverage, we hypothesized that this parameter is the most valuable measure to discriminate between patients with intact rotator cuff tendons and those with torn rotator cuff tendons.
Materials and methods Patient selection On the basis of data from previously published series, pre hoc power analysis was performed for each of the outcome measures.1-3,9,11,12,18,23 This analysis determined that for a significance level (type I error) of 5%, a sample size of 51 patients in each group was sufficient to provide a desired power of 95%. The RCT group consisted of 51 consecutive patients who underwent arthroscopic rotator cuff surgery between January 2012 and October 2012 for a degenerative full-thickness tear involving at least the supraspinatus tendon. RCTs were diagnosed by magnetic resonance imaging and were corroborated at surgery. Only patients with available preoperative true anteroposterior and standardized lateral (outlet) views were included.10,20 Patients with inflammatory disease or a history of trauma or previous surgery were excluded, as were those with an acromiohumeral distance 7 mm were included. Although discrete morphologic changes were possible, substantial modification of the bone anatomy by the presence of long-standing massive RCTs can be excluded. Nevertheless, the present study could not determine whether the demonstrated associations of different scapular morphologies with the presence of degenerative rotator cuff disease have a cause-effect relationship. In addition, our study group may have been subjected to selection bias, as only symptomatic shoulders were included. It is therefore possible that our findings would be different in a population of individuals with only asymptomatic RCTs.
Conclusion This study confirms the previously reported association of the AI, LAA, and CSA with the occurrence of degenerative RCTs. Of all the assessed parameters, the CSA allowed the most accurate prediction of a patient’s individual risk of experiencing a RCT. In contrast to these findings, neither the relationship between rotator cuff disease and different types of the acromion morphology according to Bigliani and Morrison nor the association of RCTs with flattened acromial slopes could be confirmed.
Disclaimer The authors, their immediate families, and any research foundation with which they are affiliated did not receive any financial payments or other benefits from any commercial entity related to the subject of this article.
5
References 1. Aoki M, Ishii S, Usui M. The slope of the acromion and rotator cuff impingement. Orthop Trans 1986;10:228. 2. Balke M, Schmidt C, Dedy N, Banerjee M, Bouillon B, Liem D. Correlation of acromial morphology with impingement syndrome and rotator cuff tears. Acta Orthop 2013;84:178-83. http://dx.doi.org/10. 3109/17453674.2013.773413 3. Banas MP, Miller RJ, Totterman S. Relationship between the lateral acromion angle and rotator cuff disease. J Shoulder Elbow Surg 1995; 4:454-61. 4. Bhatia DN, Debeer JF, Toit DF. Association of a large lateral extension of the acromion with rotator cuff tears. J Bone Joint Surg Am 2006;88:1889. 5. Bigliani L, Morrison D, April E. The morphology of the acromion and its relationship to rotator cuff tears. Orthop Trans 1986;10:216. 6. Hamada K, Fukuda H, Mikasa M, Kobayashi Y. Roentgenographic findings in massive rotator cuff tears. A long-term observation. Clin Orthop Relat Res 1990;254:92-6. 7. Hamid N, Omid R, Yamaguchi K, Steger-May K, Stobbs G, Keener JD. Relationship of radiographic acromial characteristics and rotator cuff disease: a prospective investigation of clinical, radiographic, and sonographic findings. J Shoulder Elbow Surg 2012;21: 1289-98. http://dx.doi.org/10.1016/j.jse.2011.09.028 8. Hughes RE, Bryant CR, Hall JM, Wening J, Huston LJ, Kuhn JE, et al. Glenoid inclination is associated with full-thickness rotator cuff tears. Clin Orthop Relat Res 2003;(407):86-91. 9. Kim JR, Ryu KJ, Hong IT, Kim BK, Kim JH. Can a high acromion index predict rotator cuff tears? Int Orthop 2012;36:1019-24. http://dx. doi.org/10.1007/s00264-012-1499-4 10. Liotard JP, Cochard P, Walch G. Critical analysis of the supraspinatus outlet view: rationale for a standard scapular Y-view. J Shoulder Elbow Surg 1998;7:134-9. 11. Miyazaki AN, Itoi E, Sano H, Fregoneze M, Santos PD, da Silva LA, et al. Comparison between the acromion index and rotator cuff tears in the Brazilian and Japanese populations. J Shoulder Elbow Surg 2011; 20:1082-6. http://dx.doi.org/10.1016/j.jse.2011.04.028 12. Moor BK, Bouaicha S, Rothenfluh DA, Sukthankar A, Gerber C. Is there an association between the individual anatomy of the scapula and the development of rotator cuff tears or osteoarthritis of the glenohumeral joint? A radiological study of the critical shoulder angle. Bone Joint J 2013;95-B:935-41. http://dx.doi.org/10.1302/0301-620X.95B7.31028 13. Musil D, Sadovsky P, Rost M, Stehlik J, Filip L. Relationship of acromial morphology and rotator cuff tears. Acta Chir Orthop Traumatol Cech 2012;79:238-42. 14. Neer CS 2nd. Anterior acromioplasty for the chronic impingement syndrome in the shoulder: a preliminary report. J Bone Joint Surg Am 1972;54:41-50. 15. Neer CS 2nd. Impingement lesions. Clin Orthop Relat Res 1983;173: 70-7. 16. Neer CS 2nd, Craig EV, Fukuda H. Cuff-tear arthropathy. J Bone Joint Surg Am 1983;65:1232-44. 17. Nicholson GP, Goodman DA, Flatow EL, Bigliani LU. The acromion: morphologic condition and age-related changes. A study of 420 scapulas. J Shoulder Elbow Surg 1996;5:1-11. 18. Nyffeler RW, Werner CM, Sukthankar A, Schmid MR, Gerber C. Association of a large lateral extension of the acromion with rotator cuff tears. J Bone Joint Surg Am 2006;88:800-5. http://dx.doi.org/10. 2106/JBJS.D.03042 19. Ozaki J, Fujimoto S, Nakagawa Y, Masuhara K, Tamai S. Tears of the rotator cuff of the shoulder associated with pathological changes in the acromion. A study in cadavera. J Bone Joint Surg Am 1988;70:1224-30. 20. Sanders TG, Jersey SL. Conventional radiography of the shoulder. Semin Roentgenol 2005;40:207-22. 21. Shah NN, Bayliss NC, Malcolm A. Shape of the acromion: congenital or acquiredda macroscopic, radiographic, and microscopic study of acromion. J Shoulder Elbow Surg 2001;10:309-16.
6 22. Tetreault P, Krueger A, Zurakowski D, Gerber C. Glenoid version and rotator cuff tears. J Orthop Res 2004;22:202-7. http://dx.doi.org/10. 1016/S0736-0266(03)00116-5 23. Torrens C, Lopez JM, Puente I, Caceres E. The influence of the acromial coverage index in rotator cuff tears. J Shoulder Elbow Surg 2007;16:347-51. http://dx.doi.org/10.1016/j.jse.2006.07.006
B.K. Moor et al. 24. Wang JC, Shapiro MS. Changes in acromial morphology with age. J Shoulder Elbow Surg 1997;6:55-9. 25. Zumstein MA, Jost B, Hempel J, Hodler J, Gerber C. The clinical and structural long-term results of open repair of massive tears of the rotator cuff. J Bone Joint Surg Am 2008;90:2423-31. http://dx.doi.org/ 10.2106/JBJS.G.00677
