Shoulder:Radiographic Evaluation of Shoulder Problems - Revision history

Alexandre.laedermann: /* Rotator Cuff Interval */

2021-08-15T16:45:29Z

Rotator Cuff Interval

Alexandre.laedermann: /* Ultrasound (US) */

2021-08-15T16:43:04Z

Ultrasound (US)

Alexandre.laedermann: /* Ultrasound (US) */

2021-08-15T16:41:12Z

Ultrasound (US)

Alexandre.laedermann: /* Rotator cuff evaluation */

2021-08-15T10:03:02Z

Rotator cuff evaluation

Alexandre.laedermann: /* Degenerative */

2021-08-15T09:45:02Z

Degenerative

Alexandre.laedermann: /* Acromiohumeral Distance */

2021-08-15T09:28:19Z

Acromiohumeral Distance

Alexandre.laedermann: /* Acromiohumeral Distance */

2021-08-15T08:42:12Z

Acromiohumeral Distance

Alexandre.laedermann: /* Critical Shoulder Angle */

2021-08-15T08:39:24Z

Critical Shoulder Angle

Alexandre.laedermann: /* Critical Shoulder Angle */

2021-08-15T08:27:16Z

Critical Shoulder Angle

Alexandre.laedermann: /* Acromial Index */

2021-08-15T08:18:59Z

Acromial Index

@@ Line 77: / Line 77: @@
 Direct signs are:
 * non-visualization of the supraspinatus tendon
-* hypoechoic discontinuity in the tendon
+*non-visualization of the supraspinatus tendon
 Indirect signs are:
 * double cortex sign
-* sagging peribursal fat sign
+*double cortex sign
-* compressibility
+*sagging peribursal fat sign
-* muscle atrophy
+*compressibility
 Secondary associated signs are:
 * cortical irregularity of greater tuberosity
-* shoulder joint effusion
+*cortical irregularity of greater tuberosity
-* Milky way sign
+*shoulder joint effusion
-* fluid along the biceps tendon
+*Milky way sign
-* fluid in the axillary pouch and posterior recess
+*fluid along the biceps tendon
 ===Rotator Cuff Interval===
-The space through which the long head of the biceps passes as it leaves the glenohumeral joint is called the rotator cuff interval. The patient position is the same as for evaluation of the long head of the biceps, with the probe being placed slightly superiorly to the bicipital groove and in the axial plane (Figure 7). The long head of the biceps is thus visualized with the subscapularis medially and the supraspinatus laterally, while the coracohumeral and superior glenohumeral ligaments surround it.<ref name=":43">Plomb-Holmes C, Clavert P, Kolo F, Tay E, Ladermann A, French Society of A. An orthopaedic surgeon's guide to ultrasound imaging of the healthy, pathological and postoperative shoulder. Orthop Traumatol Surg Res. 2018;104:S219-S232.</ref>
+The space through which the long head of the biceps passes as it leaves the glenohumeral joint is called the rotator cuff interval. The patient position is the same as for evaluation of the long head of the biceps, with the probe being placed slightly superiorly to the bicipital groove and in the axial plane (Figure). The long head of the biceps is thus visualized with the subscapularis medially and the supraspinatus laterally, while the coracohumeral and superior glenohumeral ligaments surround it.<ref name=":43">Plomb-Holmes C, Clavert P, Kolo F, Tay E, Ladermann A, French Society of A. An orthopaedic surgeon's guide to ultrasound imaging of the healthy, pathological and postoperative shoulder. Orthop Traumatol Surg Res. 2018;104:S219-S232.</ref>
 [[File:1562465913980-lg.jpg|center|thumb|900x900px|Rotator cuff interval, containing the long head of the biceps, with a longitudinal view of the subscapularis medially and transverse view of the supraspinatus laterally, while the coracohumeral and superior glenohumeral ligaments surround it. Ultrasound image (a) with superimposed anatomy (b) and patient/probe position (c). Reproduced from Plomb-Holmes et al.,<ref name=":43" /> with permission.]]
@@ Line 120: / Line 123: @@
 ====Fatty Infiltration====
-The most important negative prognostic factor is high-grade fatty infiltration of the rotator cuff muscle bellies (grade 3 or 4 fatty infiltration) (Figure 10).
+The most important negative prognostic factor is high-grade fatty infiltration of the rotator cuff muscle bellies (grade 3 or 4 fatty infiltration) (Figure).
 [[File:1562466619160-lg.jpg|center|thumb|400x400px|Sagittal view of a left shoulder computed tomography (CT) arthrogram that show a Grade 4 fatty infiltration of infraspinatus and teres minor.]]

@@ Line 96: / Line 96: @@
 The space through which the long head of the biceps passes as it leaves the glenohumeral joint is called the rotator cuff interval. The patient position is the same as for evaluation of the long head of the biceps, with the probe being placed slightly superiorly to the bicipital groove and in the axial plane (Figure 7). The long head of the biceps is thus visualized with the subscapularis medially and the supraspinatus laterally, while the coracohumeral and superior glenohumeral ligaments surround it.<ref name=":43">Plomb-Holmes C, Clavert P, Kolo F, Tay E, Ladermann A, French Society of A. An orthopaedic surgeon's guide to ultrasound imaging of the healthy, pathological and postoperative shoulder. Orthop Traumatol Surg Res. 2018;104:S219-S232.</ref>
 [[File:1562465913980-lg.jpg|center|thumb|900x900px|Rotator cuff interval, containing the long head of the biceps, with a longitudinal view of the subscapularis medially and transverse view of the supraspinatus laterally, while the coracohumeral and superior glenohumeral ligaments surround it. Ultrasound image (a) with superimposed anatomy (b) and patient/probe position (c). Reproduced from Plomb-Holmes et al.,<ref name=":43" /> with permission.]]
 =====Supraspinatus Tendon and Subacromial-Subdeltoid Bursa=====

@@ Line 74: / Line 74: @@
 ==Ultrasound (US)==
-Following X-ray evaluation, advanced imaging modalities are obtained to confirm and plan treatment. Ultrasonography is an excellent cost-effective screening tool in the office but does not allow evaluation of intra-articular pathology or easy evaluation of muscle quality.
+Following X-ray evaluation, advanced imaging modalities are obtained to confirm and plan treatment. Ultrasonography is an excellent cost-effective screening tool in the office but does not allow evaluation of intra-articular pathology or easy evaluation of muscle quality. Full-thickness tears extend from bursal to the articular surface, while partial-thickness tears are focal defects in the tendon that involve either the bursal or articular surface. Full-thickness appear on ultrasound as hypoechoic/anechoic defects in the tendon. Due to the fluid replacing tendon, cartilage shadow gets accentuated giving a double cortex or cartilage interface sign. Also, due to the defect, overlying peribursal fat dips down into the tendon gap, creating a sagging peribursal fat sign.<ref>Moosikasuwan JB, Miller TT, Burke BJ. Rotator cuff tears: clinical, radiographic, and US findings. Radiographics. 2005;25(6):1591-607</ref>
 ===Rotator Cuff Interval===

@@ Line 19: / Line 19: @@
 [[File:NSA.jpg|thumb|Neck-Shaft angle measurement. It is the angle between a perpendicular line to the anatomic neck and the axis of the humerus.]]
-==Rotator cuff evaluation==
+==Rotator Cuff Evaluation==
 ==X-rays==

@@ Line 19: / Line 19: @@
 [[File:NSA.jpg|thumb|Neck-Shaft angle measurement. It is the angle between a perpendicular line to the anatomic neck and the axis of the humerus.]]
-==Degenerative==
+==Rotator cuff evaluation==
 ===Acromial Morphology===
-The anatomical characteristics of the scapula also have an important implication in the pathologies of the shoulder. The shape of the acromion and its involvement in the lesions of the rotator cuff has been studied by numerous authors.<ref name=":5" /><ref name=":6" /><ref>D. Toivonen, M. Tuite, J. Orwin "Acromial structure and tears of the rotator cuff." ''J Shoulder Elbow Surg'', '''1995''', 4, 376-383. </ref><ref>R.E. Epstein, M.E. Schweitzer, B.G. Frieman, J.M. Fenlin, D.G. Mitchell "Hooked acromion: prevalence on MR images of painful shoulders." ''Radiology'', '''1993''', 187, 479-481.</ref> Thus, a link has been demonstrated between the radiological morphology and the risk of degenerative lesion of the rotator cuff, especially the supraspinatus with Bigliani describing 3 types of acromion, namely flat, curved or hooked.<ref name=":5" /> It shows an increase in prevalence with progression of type of acromion. However, there is a low inter-observer reliability, especially for types 2 and 3. Other studies confirm this analysis with the absence of objective criteria making the delimitation between type 2 and 3 more complicated.<ref>S.R. Jacobson, K.P. Speer, J.T. Moor, D.H. Janda, S.R. Saddemi, P. B. MacDonald, W.J. Mallon "Reliability of radiographic assessment of acromial morphology." ''J Shoulder Elbow Surg'', '''1995''', 4, 449-453.</ref> It was in 2001 that Park et al. did a study to give standardized and objective criteria to distinguish the different types based on Neer’s radiological incidence images (Figure).<ref>T.S. Park, D.W. Park, S.I. Kim, T.H. Kweon "Roentgenographic assessment of acromial morphology using supraspinatus outlet radiographs." ''Arthroscopy'', '''2001''', 17, 496-501.</ref> Thus they demonstrate a better inter-class correlation (0.94) with their measurement systems which is more objective and reliable, especially when it is necessary to distinguish type 2 and 3.
+The anatomical characteristics of the scapula also have an important implication in the pathologies of the shoulder. The shape of the acromion and its involvement in the lesions of the rotator cuff has been studied by numerous authors.<ref name=":5" /><ref name=":6" /><ref>Toivonen DA, Tuite MJ, Orwin JF.Acromial structure and tears of the rotator cuff. J Shoulder Elbow Surg. 1995;4(5):376-83</ref><ref>Epstein RE, Schweitzer ME, Frieman BG, Fenlin JM Jr, Mitchell DG. Hooked acromion: prevalence on MR images of painful shoulders. Radiology. 1993;187(2):479-81</ref> Thus, a link has been demonstrated between the radiological morphology and the risk of degenerative lesion of the rotator cuff, especially the supraspinatus with Bigliani describing 3 types of acromion, namely flat, curved or hooked.<ref name=":5" /> It shows an increase in prevalence with progression of type of acromion. However, there is a low inter-observer reliability, especially for types 2 and 3. Other studies confirm this analysis with the absence of objective criteria making the delimitation between type 2 and 3 more complicated.<ref>Jacobson SR, Speer KP, Moor JT, Janda DH, Saddemi SR, MacDonald PB, Mallon WJ. Reliability of radiographic assessment of acromial morphology. J Shoulder Elbow Surg. 1995;4(6):449-53</ref> It was in 2001 that Park et al. did a study to give standardized and objective criteria to distinguish the different types based on Neer’s radiological incidence images (Figure).<ref>Park TS, Park DW, Kim SI, Kweon TH. Roentgenographic assessment of acromial morphology using supraspinatus outlet radiographs. Arthroscopy. 2001;17(5):496-501</ref> Thus they demonstrate a better inter-class correlation (0.94) with their measurement systems which is more objective and reliable, especially when it is necessary to distinguish type 2 and 3.
 [[File:AM.jpg|thumb|Acromial morphology]]
@@ Line 52: / Line 71: @@
 [[File:AHD.jpg|thumb|Acromiohumeral distance < 7 mm is associated with a full-thickness tear.]]
 ==Conclusion==

@@ Line 48: / Line 48: @@
 ===Acromiohumeral Distance===
-Tendinopathies of the rotator cuff are frequent pathologies which may have as their origin intrinsic and/or extrinsic factors. A magnetic resonance imaging or computed tomography allows these lesions to be visualized with good precision. However, a standard X-ray marker was described long ago. This is the subacromial space (Figure). In the 1960s, Golding was one of the first to describe a link between the decrease in subacromial space and rotator cuff disease.<ref>Golding FC. The shoulder--the forgotten joint. Br J Radiol. 1962;35:149-58</ref> Later in 1970, Weiner et al. also describe an association between the reduction of the subacromial space and the tear of the rotator cuff.<ref>D.S. Weiner, I. Macnab "Superior migration of the humeral head. A radiological aid in the diagnosis of tears of the rotator cuff." ''J. Bone Joint Surg Br'', '''1970''', 52, 524-7.</ref> In 1984, Petersson describes the average distance of 9 to 10 mm for a normal acromio-humeral space, with a pathological threshold suspecting a lesion of the supraspinatus at 6 mm.<ref>C.J. Petersson, L. Redlund-Johnell "The subacromial space in normal shoulder radiographs." ''Actra Orthop Scand'', '''1984''', 55, 57-8.</ref> Thus, in the years that followed, many authors came to the same conclusion with a widely described association between a subacromial space less than 7 mm and a massive rupture of the rotator cuff<ref name=":15">N. Saupe, C.W.A. Pfirrmann, M.R. Schmid, B. Jost, C.M. L. Werner, M. Zanetti "Association between rotator cuff abnormalities and reduced acromiohumeral distance." ''Am J Roentgenol'', '''2006''', 187, 376-382.</ref><ref>L. Nové-Josserand, T.B. Edwards, D.P.O'Connor, G. Walch "The acromiohumeral and coracohumeral intervals are abnormal in rotator cuff tears with muscular fatty degeneration." ''Clin Orthop Relat Res'', '''2005''', 433, 90-96.</ref><ref>M.E. Mayerhoefer, M.J. Breitenseher, C. Wurnig, A. Roposch "Shoulder impingement: relationship of clinical symptoms and imaging criteria." ''Clin J Sport Med'', '''2009''', 19, 83-89.</ref><ref>L. Nové-Josserand, C. Lévigne, E. Noël, G. Walch "The acromio-humeral interval. A study of the factors influencing its height." ''Rev Chir Orthop Reparatrice Appar Mot'', '''1996''', 82, 379-385.</ref><ref>M.J. Scheyerer, F.E. Brunner, C. Gerber "The acromiohumeral distance and the subacromial clearance and correlated to the glenoid version." ''Orthop Traumatol Surg Res'', '''2016''', 102, 305-309.</ref> with a massive rupture of the rotator cuff described as a tear of at least two tendons, often the supraspinatus and infraspinatus.<ref>C. Gerber, B. Fuchs, J. Hodler "The results of repair of massive tears of the rotator cuff." ''J Bone Joint Surg Am'', '''2000''', 82, 505-515.</ref> Thus, Saupe et al. show in the study a strong association of the decrease of the subacromial space to less than 7 mm and a tear of the supraspinatus and infraspinatus.<ref name=":15" /> Nové-Josserand et al. explain that a decrease of the subacromial space to less than 7 mm indicates a rupture of the infraspinatus. The reduction of the space is due to the loss of the infra-spinatus lowering function with a migration of the humeral head in the space deserted by the supraspinatus. Furthermore, there is a higher rate of recurrence of rupture after surgery in a patient with a massive rupture of the cap and therefore a decreased subacromial space. Moreover, the radiological measurement showed a very good correlation whether it is compared to the scanner<ref>M.a.J. van de Sande, P.M. Rozing "Proximal migration can be measured accurately on standardized anteroposterior shoulder radiographs." ''Clin Orthop Relat Res'', '''2006''', 443, 260-265.</ref> or when comparing inter-observers.<ref>C.M.L. Werner, S.J. Conrad, D.C.Meyer, A. Keller, J. Hodler, C. Gerber "Intermethod agreement and interobserver correlation of radiographic acromiohumeral distance measurements." ''J Shoulder Elbow Surg,'' '''2008''', 17, 237-240.</ref><ref>G. Gruber, G.A. Bernhardt, H. Clar, M. Zacherl, M. Glehr, C. Wurnig "Measurement of the acromiohumeral interval on standardized anteroposterior radiographs: A prospective study of observer variability." ''J Shoulder Elbow Surg,'' '''2010''', 19, 10-13.</ref><ref>G.A. Bernhardt, M. Glehr, M. Zacherl, C. Wurnig, G. Gruber "Observer variability in the assessment of the acromiohumeral interval using anteroposterior shoulder radiographs." ''Eur J Orthop Surg Traumatol'', '''2013''', 23, 185-190.</ref> All these elements therefore make it possible to use the measurement of the subacromial space in the evaluation and the therapeutic decision-making of a patient with shoulder pain. However, this remains a good indicator in the evaluation of the posterior superior cuff without giving information on the anterior cuff.<ref>B. Middernacht, P. Winnock de Grave, G. Van Maele, L. Favard, D. Molé, L. De Wilde "What do standard radiography and clinical examination tell about the shoulder with cuff tear arthropathy?" ''J Orthop Surg Res'', '''2011''', 6, 1.</ref> In connection with the reduction of subacromial space, Hamada et al. introduced in 1990 the notion of arthropathy linked to a massive rupture of the rotator cuff.<ref name=":16" /> It declines in 5 grades progressive, each associated with radiological changes. In 2005, Walch et al. modified this classification somewhat by creating two subtypes of grade 4. However, the same year, Nové-Josserand et al. show that there is no linear progression of the Hamada classification.<ref>L. Nové-Josserand, G. Walch, P. Adeleine, P. Courpron "Effect of age on the natural history of the shoulder: a clinical and radiological study in the elderly." ''Rev Chir Orthop Reparatrice Appar Mot,'' '''2005''', 91, 508-514.</ref> However, it confirms that the tendinopathy of the rotator cuff is more involved in the aging of the shoulder than the osteoarthritis. A new study proposed in 2011 by Hamada et al. examines in more detail the different implications in terms of grades.<ref>K. Hamada, K. Yamanaka, Y. Uchiyama, T. Mikasa, M. Mikasa "A radiographic classification of massive rotator cuff tear arthritis." ''Clin Orthop Relat Res'', '''2011''', 469, 2452-2460.</ref> The greater role of a lesion involving the subscapularis from Grade 3 and a rate of recurrence of rupture after intervention more frequent from Grade 2. Thus, surgery should be considered before the subacromial space is reduced.
+Tendinopathies of the rotator cuff are frequent pathologies which may have as their origin intrinsic and/or extrinsic factors. A magnetic resonance imaging or computed tomography allows these lesions to be visualized with good precision. However, a standard X-ray marker was described long ago. This is the subacromial space (Figure). In the 1960s, Golding was one of the first to describe a link between the decrease in subacromial space and rotator cuff disease.<ref>Golding FC. The shoulder--the forgotten joint. Br J Radiol. 1962;35:149-58</ref> Later in 1970, Weiner et al. also describe an association between the reduction of the subacromial space and the tear of the rotator cuff.<ref>Weiner, DS, Macnab I. Superior migration of the humeral head. A radiological aid in the diagnosis of tears of the rotator cuff. J Bone Joint Surg Br. 1970;52(3):524-7</ref> In 1984, Petersson describes the average distance of 9 to 10 mm for a normal acromio-humeral space, with a pathological threshold suspecting a lesion of the supraspinatus at 6 mm.<ref>Petersson CJ, Redlund-Johnell I.The subacromial space in normal shoulder radiographs. Acta Orthop Scand. 1984;55(1):57-8</ref> Thus, in the years that followed, many authors came to the same conclusion with a widely described association between a subacromial space less than 7 mm and a massive rupture of the rotator cuff<ref name=":15">Saupe N, Pfirrmann CW, Schmid MR, Jost B, Werner CM, Zanetti M. Association between rotator cuff abnormalities and reduced acromiohumeral distance. AJR Am J Roentgenol. 2006;187(2):376-82</ref><ref>Nové-Josserand L, Edwards TB, O'Connor DP, Walch G. The acromiohumeral and coracohumeral intervals are abnormal in rotator cuff tears with muscular fatty degeneration. Clin Orthop Relat Res. 2005;(433):90-6</ref><ref>Mayerhoefer ME, Breitenseher MJ, Wurnig C, Roposch A. Shoulder impingement: relationship of clinical symptoms and imaging criteria. Clin J Sport Med. 2009;19(2):83-9</ref><ref>Nové-Josserand L, Lévigne C, Noël E, Walch G. [The acromio-humeral interval. A study of the factors influencing its height]. Rev Chir Orthop Reparatrice Appar Mot. 1996;82(5):379-85.</ref><ref>Scheyerer MJ, Brunner FE, Gerber C.The acromiohumeral distance and the subacromial clearance are correlated to the glenoid version. Orthop Traumatol Surg Res. 2016;102(3):305-9</ref> with a massive rupture of the rotator cuff described as a tear of at least two tendons, often the supraspinatus and infraspinatus.<ref>Gerber C, Fuchs B, Hodler J. The results of repair of massive tears of the rotator cuff.
 [[File:AHD.jpg|thumb|Acromiohumeral distance < 7 mm is associated with a full-thickness tear.]]

@@ Line 43: / Line 43: @@
 ===Critical Shoulder Angle===
-In addition to the morphology or size of the acromion, the variation of the inclination of the glenoid is a radiographic marker that may indicate rotator cuff lesions. Thus, several studies show a relationship between a high glenoid tilt and the upper migration of the humeral head.<ref>Hughes RE, Bryant CR, Hall JM, Wening J, Huston LJ, Kuhn JE, Carpenter JE, Blasier RB. Glenoid inclination is associated with full-thickness rotator cuff tears. Clin Orthop Relat Res. 2003;(407):86-91</ref><ref>Wong AS, Gallo L, Kuhn JE, Carpenter JE, Hughes RE. The effect of glenoid inclination on superior humeral head migration. J Shoulder Elbow Surg. 2003;12(4):360-4.</ref> This migration favors subacromial compression of the supraspinatus and therefore tendon tears. In 2013, Moor et al. describe a new radiological marker, the critical shoulder angle.<ref name=":11" /> The interest is to include in one measure the concept of the acromial index and the glenoid inclination. It is represented by the angle between a line connecting the upper and lower pole of the glenoid and another connecting the lower pole of the glenoid with the lateral edge of the acromion (Figure). It demonstrates an association between a tear of the cuff and a critical shoulder angle greater than 35 degrees and inversely an association between an osteoarthritis and a critical shoulder angle of less than 30 degrees. Gerber et al. confirm this relationship in a biomechanical study.<ref>Gerber C, Snedeker JG, Baumgartner D, Viehöfer AF. Supraspinatus tendon load during abduction is dependent on the size of the critical shoulder angle: A biomechanical analysis. J Orthop Res. 2014;32(7):952-7</ref> They show that the increase in critical shoulder angle is associated with an increase in shear forces, especially in degrees of mobility associated with a large number of activities of daily life. The result is a greater antero-superior instability involving more necessary activity on the part of the supraspinatus to stabilize the shoulder and leading more easily to tears. These theories and the association between critical shoulder angle, osteoarthritis and tear of the cuff are also demonstrated significantly in more recent studies.<ref>Moor BK, Röthlisberger M, Müller DA, Zumstein MA, Bouaicha S, Ehlinger M, Gerber C.Age, trauma and the critical shoulder angle accurately predict supraspinatus tendon tears. Orthop Traumatol Surg Res. 2014;100(5):489-94</ref><ref>Daggett M, Werner B, Collin P, Gauci MO, Chaoui J, Walch G. Correlation between glenoid inclination and critical shoulder angle: a radiographic and computed tomography study. J Shoulder Elbow Surg. 2015 Dec;24(12):1948-53</ref><ref>A.F. Viehöfer, C. Gerber, P. Favre, E. Bachmann, J.G. Snedeker "A large critical shoulder angle requires more rotator cuff activity to preserve joint stability." ''J Orthop Res'', '''2016''', 34, 961-968.</ref><ref>D. Blonna, A. Giani, E. Bellato, L. Mattei, M. Caló, R. Rossi, F. Castoldi "Predominance of the critical shoulder angle in the pathogenesis of degenerative diseases of the shoulder." ''J Shoulder Elbow Surg'', '''2016''', 25, 1328-1336.</ref><ref name=":13">U.J. Spiegl, M. P. Horan, S.W. Smith, C.P. Ho, P.J. Millett "The critical shoulder angle is associated with rotator cuff tears and shoulder osteoarthritis and is better assessed with radiographs over MRI." ''Knee Surg Sports Traumatol Arthrosc'', '''2016''', 24, 2244-2251.</ref><ref name=":14">L. Cherchi, J.F. Ciornohac, J. Godet, P. Clavert, J.F. Kempf "Critical shoulder angle: Measurement reproducibility and correlation with rotator cuff tendon tears." ''Orthop Traumatol Surg Res'', '''2016''', 102, 559-562. </ref> Engelhardt et al. even independently analyzed the three different parameters (acromial index, IG, critical shoulder angle) demonstrating that critical shoulder angle is the best parameter for estimating the risk of rotator cuff injury.<ref name=":12" /> This can be explained by the fact that it combines the influence of a GI and a high acromial index on the upper migration of the humeral head. However, he does not find this precision when it comes to correlating the critical shoulder angle with osteoarthritis. More recently, Chalmers et al. have achieved less satisfactory results.<ref>P.N. Chalmers, D. Salazar, K.M. Steger-May, A.M. Chamberlain, K. Yamaguchi, J.D. Keener "Does the Critical Shoulder Angle Correlate with Rotator Cuff Tear Progression?" ''Clin Orthop Relat Res'', '''2017''', 475, 1608-1617.</ref> They obtained differences of up to 2 degrees, but too low to have a significant association on the presence of a tendinopathy of the cuff. Since the critical shoulder angle is a radiological measure, it is important to have a good correlation of the measurement. Bouaicha et al. demonstrated in their study that the correlation between anteroposterior standard radiography and scanner is very satisfactory and that the differences that can occur between these two modalities are quite negligible.<ref>S. Bouaicha, C. Ehrmann, K. Slankamenac, W.D. Regan, B.K. Moor "Comparison of the critical shoulder angle in radiographs and computed tomography." ''Skeletal Radiol'', '''2014''', 43, 1053-1056.</ref> Spiegl et al. and Cherchi et al. demonstrate a good intra- and inter-observer correlation in the radiological analysis of the critical shoulder angle.<ref name=":13" /><ref name=":14" /> However, Suter et al. describe the measurement of the critical shoulder angle as a function of the spatial relationship of the scapula as a function of the radiological monitor.<ref>T. Suter, A. Gerber Popp, Y. Zhang, C. Zhang, R.Z. Tashijan, H.B. Henninger "The influence of radiographic viewing perspective and demographics on the critical shoulder angle." ''J Shoulder Elbow Surg'', '''2015''', 24, 149-158.</ref> They thus note that the critical shoulder angle is sensitive to the ante or retro-version of the scapula relative to the radiological monitor, with a change from 5 to 8 degrees which can change the critical shoulder angle measurement by 2 degrees and thus influence the clinical interpretation.
+In addition to the morphology or size of the acromion, the variation of the inclination of the glenoid is a radiographic marker that may indicate rotator cuff lesions. Thus, several studies show a relationship between a high glenoid tilt and the upper migration of the humeral head.<ref>Hughes RE, Bryant CR, Hall JM, Wening J, Huston LJ, Kuhn JE, Carpenter JE, Blasier RB. Glenoid inclination is associated with full-thickness rotator cuff tears. Clin Orthop Relat Res. 2003;(407):86-91</ref><ref>Wong AS, Gallo L, Kuhn JE, Carpenter JE, Hughes RE. The effect of glenoid inclination on superior humeral head migration. J Shoulder Elbow Surg. 2003;12(4):360-4.</ref> This migration favors subacromial compression of the supraspinatus and therefore tendon tears. In 2013, Moor et al. describe a new radiological marker, the critical shoulder angle.<ref name=":11" /> The interest is to include in one measure the concept of the acromial index and the glenoid inclination. It is represented by the angle between a line connecting the upper and lower pole of the glenoid and another connecting the lower pole of the glenoid with the lateral edge of the acromion (Figure). It demonstrates an association between a tear of the cuff and a critical shoulder angle greater than 35 degrees and inversely an association between an osteoarthritis and a critical shoulder angle of less than 30 degrees. Gerber et al. confirm this relationship in a biomechanical study.<ref>Gerber C, Snedeker JG, Baumgartner D, Viehöfer AF. Supraspinatus tendon load during abduction is dependent on the size of the critical shoulder angle: A biomechanical analysis. J Orthop Res. 2014;32(7):952-7</ref> They show that the increase in critical shoulder angle is associated with an increase in shear forces, especially in degrees of mobility associated with a large number of activities of daily life. The result is a greater antero-superior instability involving more necessary activity on the part of the supraspinatus to stabilize the shoulder and leading more easily to tears. These theories and the association between critical shoulder angle, osteoarthritis and tear of the cuff are also demonstrated significantly in more recent studies.<ref>Moor BK, Röthlisberger M, Müller DA, Zumstein MA, Bouaicha S, Ehlinger M, Gerber C.Age, trauma and the critical shoulder angle accurately predict supraspinatus tendon tears. Orthop Traumatol Surg Res. 2014;100(5):489-94</ref><ref>Daggett M, Werner B, Collin P, Gauci MO, Chaoui J, Walch G. Correlation between glenoid inclination and critical shoulder angle: a radiographic and computed tomography study. J Shoulder Elbow Surg. 2015;24(12):1948-53</ref><ref>Viehöfer AF, Snedeker JG, Baumgartner D, Gerber C. Glenohumeral joint reaction forces increase with critical shoulder angles representative of osteoarthritis-A biomechanical analysis. J Orthop Res. 2016;34(6):1047-52</ref><ref>Blonna D, Giani A, Bellato E, Mattei L, Caló M, Rossi R, Castoldi F. Predominance of the critical shoulder angle in the pathogenesis of degenerative diseases of the shoulder. J Shoulder Elbow Surg. 2016 Aug;25(8):1328-36</ref><ref name=":13">Spiegl UJ, Horan MP, Smith SW, Ho CP, Millett PJ. The critical shoulder angle is associated with rotator cuff tears and shoulder osteoarthritis and is better assessed with radiographs over MRI. Knee Surg Sports Traumatol Arthrosc. 2016;24(7):2244-51</ref><ref name=":14">Cherchi L, Ciornohac JF, Godet J, Clavert P, Kempf JF. Critical shoulder angle: Measurement reproducibility and correlation with rotator cuff tendon tears. Orthop Traumatol Surg Res. 2016;102(5):559-62</ref> Engelhardt et al. even independently analyzed the three different parameters (acromial index, IG, critical shoulder angle) demonstrating that critical shoulder angle is the best parameter for estimating the risk of rotator cuff injury.<ref name=":12" /> This can be explained by the fact that it combines the influence of a GI and a high acromial index on the upper migration of the humeral head. However, he does not find this precision when it comes to correlating the critical shoulder angle with osteoarthritis. More recently, Chalmers et al. have achieved less satisfactory results.<ref>Chalmers PN, Salazar D, Steger-May K, Chamberlain AM, Yamaguchi K, Keener JD. Does the Critical Shoulder Angle Correlate With Rotator Cuff Tear Progression? Clin Orthop Relat Res. 2017;475(6):1608-1617</ref> They obtained differences of up to 2 degrees, but too low to have a significant association on the presence of a tendinopathy of the cuff. Since the critical shoulder angle is a radiological measure, it is important to have a good correlation of the measurement. Bouaicha et al. demonstrated in their study that the correlation between anteroposterior standard radiography and scanner is very satisfactory and that the differences that can occur between these two modalities are quite negligible.<ref>Bouaicha S, Ehrmann C, Slankamenac K, Regan WD, Moor BK. Comparison of the critical shoulder angle in radiographs and computed tomography. Skeletal Radiol. 2014;43(8):1053-6</ref> Spiegl et al. and Cherchi et al. demonstrate a good intra- and inter-observer correlation in the radiological analysis of the critical shoulder angle.<ref name=":13" /><ref name=":14" /> However, Suter et al. describe the measurement of the critical shoulder angle as a function of the spatial relationship of the scapula as a function of the radiological monitor.<ref>Suter T, Gerber Popp A, Zhang Y, Zhang C, Tashjian RZ, Henninger HB. The influence of radiographic viewing perspective and demographics on the critical shoulder angle. J Shoulder Elbow Surg. 2015;24(6):e149-58</ref> They thus note that the critical shoulder angle is sensitive to the ante or retro-version of the scapula relative to the radiological monitor, with a change from 5 to 8 degrees which can change the critical shoulder angle measurement by 2 degrees and thus influence the clinical interpretation.
 [[File:CSA.jpg|thumb|The critical shoulder angle. is the angle between a line from de superior border of the glenoid to its inferior border and a line from the inferior border of the glenoid to the lateral border of the acromion.]]

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 ===Acromial Index===
-Recently, Nyffeler et al. were interested in the implication of the extension of the acromion in the tears of the rotator cuff.<ref name=":7" /> Their hypothesis was that a broad acromion implies higher deltoid ascending forces which favors impingement and degenerative changes. They therefore describe the radiological measurement of the acromial index which represents the ratio between the glenoid-acromion distance and that between the glenoid-greater tuberosity (Figure). There is therefore an association between a high acromial index and a degenerative lesion of the rotator cuff, thus allowing it to be predicted radiologically. Conversely, they describe an increase in compressive forces on the glenoid when the acromion is short and thus the acromial index low. This increase in compressive force would therefore favor the appearance of glenohumeral arthritis. These findings are confirmed by other studies that also demonstrate an association between elevated acromial index and a tear in the rotator cuff,<ref>A.N. Miyazaki, M. Fregoneze, P.D. Santos, L. A. Da Silva, É,M. Martel, L. G. Debom, M. L. Andrade, S.L. Checchia "Radiographic Study on the Acromion Index and Its Relationship with Rotator Cuff Tears." ''Rev Bras Ortop (English Ed)'', '''2010''', 45, 151-154.</ref><ref name=":12">C. Engelhardt, A. Farron, F. Becce, N. Place, D.P. Pioletti, A. Terrier "Effects of glenoid inclination and acromion index on humeral head translation and glenoid articular cartilage strain." ''J Shoulder and Elbow Surg'', '''2017''', 26, 157-164. </ref> including one also demonstrating higher acromial index in patients with recurrences of postoperative rotator cuff tears.<ref>M.A. Zumstein, B. Jost, J. Hempel, J. Hodler, C. Gerber "The clinical and structural long-term results of open repair of massive tears of the rotator cuff." ''J Bone Jt Surg Ser A'', '''2008''', 90, 2423-2431.</ref> The involvement of the acromial index in the pathologies of the rotator cuff is not however unanimous.<ref name=":9">J. Kircher, M. Morhard, I. Gavriilidis, P. Magosch, S. Lichtenberg, P. Habermeyer "Is there an association between a low acromion index and osteoarthritis of the shoulder?" ''Int Orthop'', '''2010''', 34, 1005-1010.</ref><ref>J.B. Ames, M.P. Horan, O.A. Van der Meijden, M.J. Leake, P.J. Millett "Association between acromial index and outcomes following arthroscopic repair of full-thickness rotator cuff tears." ''J Bone Jt Surg Am'', '''2012''', 94, 1862-1869.</ref><ref name=":10">N. Hamid, R. Omid, K. Yamaguchi, K. Steger-May, G. Stobbs, J.D. Keener "Relationship of radiographic acromial characteristics and rotator cuff disease: A prospective investigation of clinical, radiographic, and sonographic findings." ''J Shoulder Elbow Surg'', '''2012''', 21, 1289-1298.</ref> Hamid et al. do not demonstrate any significant association between elevated acromial index and rotator cuff disease,<ref name=":10" /> while Kircher et al. do not show an association between a low acromial index and glenohumeral arthritis, which refutes the theoretical concept of a low acromial index resulting in increased contact pressure.<ref name=":9" /> Furthermore, Melean et al. do not find correlation between acromial index and the rate of recurrence of rupture of the rotator cuff after surgery. The importance of the acromial index in assessing a shoulder radiograph remains controversial.
+Recently, Nyffeler et al. were interested in the implication of the extension of the acromion in the tears of the rotator cuff.<ref name=":7" /> Their hypothesis was that a broad acromion implies higher deltoid ascending forces which favors impingement and degenerative changes. They therefore describe the radiological measurement of the acromial index which represents the ratio between the glenoid-acromion distance and that between the glenoid-greater tuberosity (Figure). There is therefore an association between a high acromial index and a degenerative lesion of the rotator cuff, thus allowing it to be predicted radiologically. Conversely, they describe an increase in compressive forces on the glenoid when the acromion is short and thus the acromial index low. This increase in compressive force would therefore favor the appearance of glenohumeral arthritis. These findings are confirmed by other studies that also demonstrate an association between elevated acromial index and a tear in the rotator cuff,<ref>Miyazaki AN, Fregoneze M, Santos PD, Da Silva LA, Martel ÉM, Debom LG, , Andrade ML, Checchia SL. Radiographic Study on the Acromion Index and Its Relationship with Rotator Cuff Tears. Rev Bras Ortop (English Ed). 2010;45:151-154</ref><ref name=":12">Engelhardt C, Farron A, Becce F, Place N, Pioletti DP, Terrier A.Effects of glenoid inclination and acromion index on humeral head translation and glenoid articular cartilage strain. J Shoulder Elbow Surg. 2017;26(1):157-164</ref> including one also demonstrating higher acromial index in patients with recurrences of postoperative rotator cuff tears.<ref>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
-<br />
+[[File:AI.jpg|thumb|Acromial Index. GH = glenohumeral distance; GA glenoacromial distance. AI = GA/GH.]]
 ===Critical Shoulder Angle===