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The Digitation Sign Facilitates Diagnosis of Shoulder Subscapularis Lesions on Preoperative Magnetic Resonance Imaging

Open AccessPublished:February 11, 2022DOI:https://doi.org/10.1016/j.asmr.2021.12.019

      Purpose

      The purposes of this study were to investigate a radiographic sign found on coronal magnetic resonance imaging (MRI) sequences in subscapularis (SSC) pathology, reporting interobserver reliability data and sensitivity and specificity; and to correlate the preoperative assessment of SSC pathology with intraoperative assessment of the SSc during shoulder arthroscopy.

      Methods

      A consecutive series of patients undergoing arthroscopic rotator cuff repair from January 2020 to December 2020 were examined. The positive diagnosis of a subscapularis tendon tear was prospectively determined and confirmed by arthroscopy. The “digitation sign” was assessed by 3 independent shoulder-trained fellows when evaluating the SSC in the coronal plane on T2-weighted images.

      Results

      Of the 132 patients included, 74 (56%) had SSC tendon tears confirmed during arthroscopy. Interobserver agreement for digitation sign was substantial (k= 0.640). Sensitivity for digitation sign only was 74.3%; for criteria of Adams et al. (Accuracy of preoperative magnetic resonance imaging in predicting a subscapularis tendon tear based on arthroscopy; Arthroscopy 2010;26:1427-1433) only, 83.8%; and for the combination of the 2 methods, 89.2%. Specificity was 84.5% for digitation sign only, 77.6% for Adams et al. criteria only, and 67.2% for the combination of the 2 methods. Sensitivity is statistically better when the digitation sign is added to the Adams et al. criteria for detection of SSC lesions. As expected, specificity is statistically lower. SSC tears are significantly associated with biceps lesions.

      Conclusion

      Preoperative systematic MRI evaluation by shoulder surgeons can diagnose subscapularis lesions by using the digitation sign in the coronal plane along with Adams et al. criteria, leading to good sensitivity. This easy-to-apply sign can be helpful in the initial MRI evaluation in the coronal plane, with improved sensitivity when combined with a systematic approach.

      Level of Evidence

      II, study of diagnostic test.
      Reliable preoperative assessment of subscapularis (SSC) tears remains challenging because of limited sensitivity with physical examination maneuvers
      • Gerber C.
      • Krushell R.J.
      Isolated rupture of the tendon of the subscapularis muscle. Clinical features in 16 cases.
      ,
      • Hegedus E.J.
      • Goode A.
      • Campbell S.
      • et al.
      Physical examination tests of the shoulder: A systematic review with meta-analysis of individual tests.
      and preoperative imaging.
      • Barth J.R.H.
      • Burkhart S.S.
      • De Beer J.F.
      The bear-hug test: A new and sensitive test for diagnosing a subscapularis tear.
      • Burkhart S.S.
      • Brady P.C.
      Arthroscopic subscapularis repair: Surgical tips and pearls A to Z.
      • Teefey S.A.
      • Rubin D.A.
      • Middleton W.D.
      • Hildebolt C.F.
      • Leibold R.A.
      • Yamaguchi K.
      Detection and quantification of rotator cuff tears. Comparison of ultrasonographic, magnetic resonance imaging, and arthroscopic findings in seventy-one consecutive cases.
      Little inter- and intraobserver agreement is observed in the classification of subscapularis tendon tears, and there is significantly higher agreement based on arthroscopic evaluation rather than magnetic resonance imaging (MRI).
      • Smucny M.
      • Shin E.C.
      • Zhang A.L.
      • et al.
      Poor agreement on classification and treatment of subscapularis tendon tears.
      Recognition of SSC tears on MRI is likely underestimated owing to the anatomy of the SSC insertion and its proximity to the ligamentous anatomy of the biceps pulley.
      • Eren I.
      • Ozben H.
      • Gunerbuyuk C.
      • et al.
      Rotator cuff tear characteristics: How comparable are the pre-operative MRI findings with intra-operative measurements following debridement during arthroscopic repair?.
      • Shi L.L.
      • Mullen M.G.
      • Freehill M.T.
      • Lin A.
      • Warner J.J.P.
      • Higgins L.D.
      Accuracy of long head of the biceps subluxation as a predictor for subscapularis tears.
      • Vinson E.N.
      • Wittstein J.
      • Garrigues G.E.
      • Taylor D.C.
      MRI of selected abnormalities at the anterior superior aspect of the shoulder: Potential pitfalls and subtle diagnoses.
      The SSC has 4 to 6 tendinous slips arising from the multipennate muscle that coalesce to form a robust flattened tendon in the superior two-thirds of the muscle, which attach to the lesser tuberosity.
      • Arai R.
      • Mochizuki T.
      • Yamaguchi K.
      • et al.
      Functional anatomy of the superior glenohumeral and coracohumeral ligaments and the subscapularis tendon in view of stabilization of the long head of the biceps tendon.
      • Morag Y.
      • Jamadar D.A.
      • Miller B.
      • Dong Q.
      • Jacobson J.A.
      The subscapularis: Anatomy, injury, and imaging.
      • Yoo J.C.
      • Rhee Y.G.
      • Shin S.J.
      • et al.
      Subscapularis tendon tear classification based on 3-dimensional anatomic footprint: A cadaveric and prospective clinical observational study.
      SSC tears are typically assessed on axial and sagittal sequences and can manifest with interrupted continuity of the tendon and signal hyperintensity on the T2-weighted images.
      • Morag Y.
      • Jamadar D.A.
      • Miller B.
      • Dong Q.
      • Jacobson J.A.
      The subscapularis: Anatomy, injury, and imaging.
      ,
      • Adams C.R.
      • Schoolfield J.D.
      • Burkhart S.S.
      Accuracy of preoperative magnetic resonance imaging in predicting a subscapularis tendon tear based on arthroscopy.
      ,
      • Foad A.
      • Wijdicks C.A.
      The accuracy of magnetic resonance imaging and magnetic resonance arthrogram versus arthroscopy in the diagnosis of subscapularis tendon injury.
      Medial subluxation of the long head of the biceps tendon can also be suggestive of SSC pathology,
      • Shi L.L.
      • Mullen M.G.
      • Freehill M.T.
      • Lin A.
      • Warner J.J.P.
      • Higgins L.D.
      Accuracy of long head of the biceps subluxation as a predictor for subscapularis tears.
      ,
      • Adams C.R.
      • Schoolfield J.D.
      • Burkhart S.S.
      Accuracy of preoperative magnetic resonance imaging in predicting a subscapularis tendon tear based on arthroscopy.
      ,
      • Godenèche A.
      • Nové-Josserand L.
      • et al.
      French Society for Arthroscopy (SFA)
      Relationship between subscapularis tears and injuries to the biceps pulley.
      and improvement is needed in MRI techniques.
      • Foad A.
      • Wijdicks C.A.
      The accuracy of magnetic resonance imaging and magnetic resonance arthrogram versus arthroscopy in the diagnosis of subscapularis tendon injury.
      To improve the diagnostic accuracy and reliability of SSC tears based on first-time MRI analyses, various systematic approaches and sequences have been attempted.
      • Adams C.R.
      • Schoolfield J.D.
      • Burkhart S.S.
      Accuracy of preoperative magnetic resonance imaging in predicting a subscapularis tendon tear based on arthroscopy.
      ,
      • Adams C.R.
      • Brady P.C.
      • Koo S.S.
      • et al.
      A systematic approach for diagnosing subscapularis tendon tears with preoperative magnetic resonance imaging scans.
      ,
      • Furukawa R.
      • Morihara T.
      • Arai Y.
      • et al.
      Diagnostic accuracy of magnetic resonance imaging for subscapularis tendon tears using radial-slice magnetic resonance images.
      Adams et al.
      • Adams C.R.
      • Brady P.C.
      • Koo S.S.
      • et al.
      A systematic approach for diagnosing subscapularis tendon tears with preoperative magnetic resonance imaging scans.
      used axial and sagittal MRI images to define a set of criteria to more reliably diagnose SSC tears confirmed during shoulder arthroscopy. Although this approach improved their previously reported recognition of SSC pathology, 27% of SSC tears were still not identified on MRI.
      The purposes of this study were to investigate a radiographic sign found on coronal magnetic resonance imaging (MRI) sequences in subscapularis (SSC) pathology, reporting interobserver reliability data and sensitivity and specificity, and to correlate the preoperative assessment of SSC pathology with an intraoperative assessment of the SSC during shoulder arthroscopy. We hypothesized that, in the presence of SSC pathology, the normal
      • Burkhart S.S.
      • Brady P.C.
      Arthroscopic subscapularis repair: Surgical tips and pearls A to Z.
      • Teefey S.A.
      • Rubin D.A.
      • Middleton W.D.
      • Hildebolt C.F.
      • Leibold R.A.
      • Yamaguchi K.
      Detection and quantification of rotator cuff tears. Comparison of ultrasonographic, magnetic resonance imaging, and arthroscopic findings in seventy-one consecutive cases.
      • Smucny M.
      • Shin E.C.
      • Zhang A.L.
      • et al.
      Poor agreement on classification and treatment of subscapularis tendon tears.
      distinct tendinous slips of SSC defining clear digitations would be disrupted on T2-weighted coronal oblique sequences.

      Methods

      Study Design

      This is a retrospective analysis of a prospectively enrolled series of consecutive patients undergoing arthroscopic rotator cuff repair performed by a single surgeon (L.N.) from January 2020 to December 2020. The study was conducted according to the Declaration of Helsinki principles and was approved by the local institutional ethics review board (IRB COS-RGDS-2020-12-005); all patients gave informed written consent. The inclusion criteria required that all patients had a preoperative MRI within 18 months of surgery, were age >18 years, and underwent primary arthroscopic rotator cuff repair. Furthermore, although several different MRI protocols were used by referring physicians, all protocols needed to have T2-weighted coronal oblique, axial, and sagittal oblique sequences and T1-weighted sequences to be included. Correct sequences were extracted and validated by 1 fellow (A.N.) from preoperative DICOMS, and then interpreted by the 2 other fellows (Y.S., M.N.). The positive diagnosis of a subscapularis tendon tear was prospectively determined by the senior surgeon and confirmed by arthroscopy. Patient demographics included age, sex, and operative side.

      MRI Interpretation

      All MRI scans were interpreted independently by 3 orthopedic fellows trained in shoulder surgery, who were blinded from the arthroscopic findings. The fellows were trained by the senior surgeon and instructed in a systematic method
      • Adams C.R.
      • Brady P.C.
      • Koo S.S.
      • et al.
      A systematic approach for diagnosing subscapularis tendon tears with preoperative magnetic resonance imaging scans.
      upon their arrival at the fellowship. First, images were analyzed together until 100% agreement was reached between the senior surgeon and the fellow so that the latter could perform their analyses individually. DICOMS were examined with RadiAnt DICOM Viewer 2020.2.2.
      According to Adams et al.
      • Adams C.R.
      • Brady P.C.
      • Koo S.S.
      • et al.
      A systematic approach for diagnosing subscapularis tendon tears with preoperative magnetic resonance imaging scans.
      criteria, the SSC was evaluated in axial, sagittal oblique, and coronal oblique planes. Tears were considered positive if the continuity of the subscapularis tendon was interrupted or signal hyperintensity was present on the T2-weighted images inside the tendon structure. In addition, tears of the involved rotator cuff tendons were recorded descriptively. To be close to real-life conditions, every MRI protocol meeting the above requirements was accepted.
      The “digitation sign” was assessed when evaluating the SSC in the coronal plane on T2-weighted images. A normal appearance was defined as having ≥2 distinctly visible tendinous bands (1 superior and 1 inferior) that coalesced into a single anatomic structure all the way to the proximal aspect of the lesser tuberosity (Fig. 1). Additional inferior tendinous bands could be observed. If ≥1 (typically superior) tendinous bands were not visible at the level of the lesser tuberosity on T2-weighted coronal oblique images, the digitation sign was defined as positive (Fig. 2). A normal appearance of the SSC with all its digitations was considered a negative digitation sign.
      Figure thumbnail gr1
      Fig 1Coronal magnetic resonance imaging (MRI) subscapularis view in right shoulder. No lesion is suspected with complete digitations; digitation sign is considered negative.
      Figure thumbnail gr2
      Fig 2Coronal magnetic resonance imaging (MRI) subscapularis view in right shoulders. Subscapularis lesions are suspected with incomplete digitations; digitation sign is considered positive. A, grade II; B, grade III; C, grade IV. Grades were defined perioperatively according to French Society for Arthroscopy (SFA) and Lafosse et al. classifications.

      Arthroscopic Procedure

      All patients underwent primary arthroscopic rotator cuff repair by a senior shoulder surgeon (L.N.). Shoulder arthroscopy was performed in the beach chair position under general anesthesia after preoperative interscalene block. Standard diagnostic arthroscopy was accomplished through a posterior viewing portal. Evaluation of the SSC was carried out with a 30° arthroscope as previously described.
      • Gasbarro G.
      • Neyton L.
      The arthroscopic “montgolfier double-row knotless” rotator cuff repair technique.
      SSC tears were classified according to the description of Lafosse et al.
      • Lafosse L.
      • Lanz U.
      • Saintmard B.
      • Campens C.
      Arthroscopic repair of subscapularis tear: Surgical technique and results.
      and the French Society for Arthroscopy (SFA) classification.
      • Toussaint B.
      • Barth J.
      • Charousset C.
      • et al.
      New endoscopic classification for subscapularis lesions.
      This measurement represented an ordinal measure of subscapularis tendon tear size and is based on the proximal-to-distal distance. In the case of a “hidden” lesion, the biceps gutter was debrided for later biceps tenodesis, as previously described.
      • Burkhart S.S.
      • Brady P.C.
      Arthroscopic subscapularis repair: Surgical tips and pearls A to Z.
      Concomitant shoulder pathology, including glenohumeral joint arthritis, biceps pathology, and labral lesions, was also reported. In the setting of biceps pathology, a suprapectoral tenodesis was performed with an interference screw.
      • Amouyel T.
      • Le Moulec Y.P.
      • Tarissi N.
      • Saffarini M.
      • Courage O.
      Arthroscopic biceps tenodesis using interference screw fixation in the bicipital groove.

      Sample Size Estimation

      We performed the sample size estimation using proportion comparison test to fix a proportion of 70%,
      • Adams C.R.
      • Brady P.C.
      • Koo S.S.
      • et al.
      A systematic approach for diagnosing subscapularis tendon tears with preoperative magnetic resonance imaging scans.
      targeting a statistical power of 80% with a significance level of 5% and an estimated prevalence of 50%. A sample of ≥122 shoulders was determined. Considering sample loss, we decided to include 132 shoulders.

      Statistical Analysis

      Statistical analysis was conducted comparing SSC tendon tears recognized during shoulder arthroscopy (gold standard) to those diagnosed preoperatively by MRI. In addition, descriptive data analysis was conducted depending on the nature of the considered criteria. For quantitative data, this included number of observed values, mean, standard deviation, median, and minimum and maximum. For qualitative data, this included the number of observed values and the number and percentage of patients per class. Comparison between variables was assessed using chi-squared or Fisher’s exact test for categorical variables and Student’s t test or Wilcoxon test for quantitative variables. Normality of variables was checked. Fleiss’s κ coefficient and standard error were calculated to measure interobserver agreement between 3 raters. The values of κ were interpreted as follows: <0, poor agreement; 0.01 to 0.20, slight agreement; 0.21 to 0.40, fair agreement; 0.41 to 0.60, moderate agreement; 0.61 to 0.80, substantial agreement; and 0.81 to 1.00, almost perfect agreement. Comparisons for sensitivity and specificity were performed with a McNemar test. All calculations were made with SAS for Windows (version 9.4; SAS Institute, Cary, NC), with the level of statistical significance set at P < .05.

      Results

      Population Characteristics

      Of the 197 patients enrolled, 43 had a computed tomography (CT) arthrogram preoperatively, 21 had no complete available DICOM series, and 1 had previous surgery on the examined shoulder. Sixty-five patients were therefore excluded from the study. Of the 132 patients included, 74 (56%) had SSC tendon tears confirmed during arthroscopy. The demographics of the patients are presented in Table 1. The groups were similar.
      Table 1Demographic characteristics
      CharacteristicEntire PopulationSSC Tears GroupIntact SSC groupP Value
      n1327458
      Sex.214
       Female482325
       Male845133
      Age (years)58 (28, 82)59 (41, 82)57 (28, 78).181
      Operated side.956
       Right854837
       Left472621
      Laterality630
       Right1277157
       Left431
      Delay between presentation and surgery (mo)3.1 (0, 18)2.7 (0, 11)3.5 (0, 18).181
      Data are mean (minimum, maximum) or n, unless specified otherwise.

      Interobserver Reliability

      The interobserver analysis is presented in Table 2. Interobserver agreement for digitation sign was substantial, with a κ coefficient of 0.640.
      Table 2Interobserver analysis
      ItemAdams et al. Criteria
      • Adams C.R.
      • Brady P.C.
      • Koo S.S.
      • et al.
      A systematic approach for diagnosing subscapularis tendon tears with preoperative magnetic resonance imaging scans.
      Axial InjuryBiceps SubluxationSagittal InjuryAtrophyDigitation sign
      κ Coefficient0.5130.5070.2510.5790.2030.640
      AgreementModerateModerateFairModerateSlightSubstantial

      Sensitivity and Specificity Analysis

      Fifty-five (74.3%) SSC lesions were correctly diagnosed with digitation sign only, 62 (83.8%) with Adams et al.
      • Adams C.R.
      • Brady P.C.
      • Koo S.S.
      • et al.
      A systematic approach for diagnosing subscapularis tendon tears with preoperative magnetic resonance imaging scans.
      criteria only, and 66 (89.2%) with the combination of the 2 methods. Forty-nine (84.5%) intact SSC tendons were correctly diagnosed with digitation sign only, 45 (77.6%) with Adams et al.
      • Adams C.R.
      • Brady P.C.
      • Koo S.S.
      • et al.
      A systematic approach for diagnosing subscapularis tendon tears with preoperative magnetic resonance imaging scans.
      criteria only, and 39 (67.2%) with the combination of the 2 methods. Sensitivity is statistically better when the digitation sign is added to the Adams et al.
      • Adams C.R.
      • Brady P.C.
      • Koo S.S.
      • et al.
      A systematic approach for diagnosing subscapularis tendon tears with preoperative magnetic resonance imaging scans.
      criteria for detection of SSC injury. As expected, specificity is statistically lower. Sensitivity and specificity combinations are shown in Table 3.
      Table 3Sensitivity analysis
      Test attributeDigitation Sign (%)Adams et al. Criteria
      • Adams C.R.
      • Brady P.C.
      • Koo S.S.
      • et al.
      A systematic approach for diagnosing subscapularis tendon tears with preoperative magnetic resonance imaging scans.
      (%)
      Digitation sign + Adams et al. Criteria (%)P Value
      Sensitivity74.383.889.2.046
      Specificity84.577.667.2.014

      Accuracy According to Lesion Classifications

      The accuracy of the digitation sign and Adams et al.
      • Adams C.R.
      • Brady P.C.
      • Koo S.S.
      • et al.
      A systematic approach for diagnosing subscapularis tendon tears with preoperative magnetic resonance imaging scans.
      criteria in relation to the Lafosse et al.
      • Lafosse L.
      • Lanz U.
      • Saintmard B.
      • Campens C.
      Arthroscopic repair of subscapularis tear: Surgical technique and results.
      and SFA
      • Toussaint B.
      • Barth J.
      • Charousset C.
      • et al.
      New endoscopic classification for subscapularis lesions.
      classifications are shown in Table 4. Adams et al.
      • Adams C.R.
      • Brady P.C.
      • Koo S.S.
      • et al.
      A systematic approach for diagnosing subscapularis tendon tears with preoperative magnetic resonance imaging scans.
      criteria were more accurate than digitation sign in diagnosing lower-grade SSC lesions; however, both methods combined yielded the highest sensitivity.
      Table 4Detection of subscapularis (SSC) tears according to lesion grade
      Grade of SSC tearOverall SSC Tears (n = 74)Positive Digitation Sign (%)Positive Adams et al. Criteria
      • Adams C.R.
      • Brady P.C.
      • Koo S.S.
      • et al.
      A systematic approach for diagnosing subscapularis tendon tears with preoperative magnetic resonance imaging scans.
      (%)
      Positive Digitation Sign + Adams Criteria (%)
      Lafosse et al.
      • Lafosse L.
      • Lanz U.
      • Saintmard B.
      • Campens C.
      Arthroscopic repair of subscapularis tear: Surgical technique and results.
       I or II5537 (67.2)43 (78.2)49 (89)
       III or IV1918 (94.7)19 (100)19 (100)
      French Society for Arthroscopy
      • Toussaint B.
      • Barth J.
      • Charousset C.
      • et al.
      New endoscopic classification for subscapularis lesions.
       1 or 26445 (70.3)52 (81.3)56 (87.5)
       3 or 41010 (100)10 (100)10 (100)
      Data are n (%).

      Concomitant Pathology

      Concomitant pathologies during arthroscopic exploration are shown in Table 5. SSC tears were significantly associated with biceps lesions.
      Table 5Concomitant lesions
      LesionsEntire Population (n = 132)SSC Tears Group (n = 74)Intact SSC Group (n = 58)P Value
      Supraspinatus1287157.630
      Infraspinatus1096148.855
      Biceps835726<.0001
      Old biceps rupture963.731
      Abbreviation: SSC, subscapularis.

      Discussion

      The principal findings of this study show that preoperative systematic MRI evaluation by orthopedic surgeons can successfully diagnose subscapularis lesions by using the digitation sign in the coronal plane in conjunction with Adams et al.
      • Adams C.R.
      • Brady P.C.
      • Koo S.S.
      • et al.
      A systematic approach for diagnosing subscapularis tendon tears with preoperative magnetic resonance imaging scans.
      criteria, leading to increased sensitivity.
      Subscapularis tears are common shoulder lesions, but diagnostic accuracy based on physical examination remains poor.
      • Gerber C.
      • Krushell R.J.
      Isolated rupture of the tendon of the subscapularis muscle. Clinical features in 16 cases.
      ,
      • Barth J.R.H.
      • Burkhart S.S.
      • De Beer J.F.
      The bear-hug test: A new and sensitive test for diagnosing a subscapularis tear.
      These tears are technically demanding for arthroscopic surgeons in both diagnosis and repair.
      • Burkhart S.S.
      • Brady P.C.
      Arthroscopic subscapularis repair: Surgical tips and pearls A to Z.
      ,
      • Lo I.K.Y.
      • Burkhart S.S.
      The comma sign: An arthroscopic guide to the torn subscapularis tendon.
      An accurate and reliable imaging diagnosis is desirable to adapt surgical treatment strategy.
      • Vinson E.N.
      • Wittstein J.
      • Garrigues G.E.
      • Taylor D.C.
      MRI of selected abnormalities at the anterior superior aspect of the shoulder: Potential pitfalls and subtle diagnoses.
      The present study describes a simple MRI sign in the coronal plane, the digitation sign, with substantial interobserver reliability, good proper specificity, and improved sensitivity when added to Adams et al.
      • Adams C.R.
      • Brady P.C.
      • Koo S.S.
      • et al.
      A systematic approach for diagnosing subscapularis tendon tears with preoperative magnetic resonance imaging scans.
      criteria, confirming our hypothesis.
      Recent advances in preoperative imaging and operative techniques have improved the ability to diagnose and treat subscapularis tendon tears,
      • Lafosse L.
      • Lanz U.
      • Saintmard B.
      • Campens C.
      Arthroscopic repair of subscapularis tear: Surgical technique and results.
      ,
      • Neyton L.
      • Daggett M.
      • Kruse K.
      • Walch G.
      The hidden lesion of the subscapularis: Arthroscopically revisited.
      with good results.
      • Denard P.J.
      • Jiwani A.Z.
      • Lädermann A.
      • Burkhart S.S.
      Long-term outcome of a consecutive series of subscapularis tendon tears repaired arthroscopically.
      Coincidentally, the incidence of SSC tendon tears recognized and treated at the time of arthroscopy has increased substantially.
      • Lo I.K.Y.
      • Burkhart S.S.
      The comma sign: An arthroscopic guide to the torn subscapularis tendon.
      ,
      • Neyton L.
      • Daggett M.
      • Kruse K.
      • Walch G.
      The hidden lesion of the subscapularis: Arthroscopically revisited.
      It is important to note that intraoperative assessment of partial SSC tears can often be challenging to identify and have therefore been referred to as “hidden lesions.”
      • Foad A.
      • Wijdicks C.A.
      The accuracy of magnetic resonance imaging and magnetic resonance arthrogram versus arthroscopy in the diagnosis of subscapularis tendon injury.
      ,
      • Walch G.
      • Nove-Josserand L.
      • Levigne C.
      • Renaud E.
      Tears of the supraspinatus tendon associated with “hidden” lesions of the rotator interval.
      Numerous MRI signs have been investigated to diagnose subscapularis lesions,
      • Adams C.R.
      • Schoolfield J.D.
      • Burkhart S.S.
      Accuracy of preoperative magnetic resonance imaging in predicting a subscapularis tendon tear based on arthroscopy.
      ,
      • Baptista E.
      • Malavolta E.A.
      • Gracitelli M.E.C.
      • et al.
      Diagnostic accuracy of MRI for detection of tears and instability of proximal long head of biceps tendon: An evaluation of 100 shoulders compared with arthroscopy.
      • Li X.X.
      • Schweitzer M.E.
      • Bifano J.A.
      • Lerman J.
      • Manton G.L.
      • El-Noueam K.I.
      MR evaluation of subscapularis tears.
      • Pfirrmann C.W.
      • Zanetti M.
      • Weishaupt D.
      • Gerber C.
      • Hodler J.
      Subscapularis tendon tears: Detection and grading at MR arthrography.
      • Tung G.A.
      • Yoo D.C.
      • Levine S.M.
      • Brody J.M.
      • Green A.
      Subscapularis tendon tear: Primary and associated signs on MRI.
      • Zhang H.
      • Zhang Q.
      • Li Z.L.
      Coracohumeral index and coracoglenoid inclination as predictors for different types of degenerative subscapularis tendon tears.
      with often good or excellent specificity but lack of sensitivity. The first ones compared MRI diagnosis to open or arthroscopic procedures,
      • Pfirrmann C.W.
      • Zanetti M.
      • Weishaupt D.
      • Gerber C.
      • Hodler J.
      Subscapularis tendon tears: Detection and grading at MR arthrography.
      ,
      • Tung G.A.
      • Yoo D.C.
      • Levine S.M.
      • Brody J.M.
      • Green A.
      Subscapularis tendon tear: Primary and associated signs on MRI.
      but the superiority of arthroscopic techniques to determine SSC tears, particularly on the articular side, is well described in the literature.
      • Burkhart S.S.
      • Brady P.C.
      Arthroscopic subscapularis repair: Surgical tips and pearls A to Z.
      ,
      • Eren I.
      • Ozben H.
      • Gunerbuyuk C.
      • et al.
      Rotator cuff tear characteristics: How comparable are the pre-operative MRI findings with intra-operative measurements following debridement during arthroscopic repair?.
      ,
      • Foad A.
      • Wijdicks C.A.
      The accuracy of magnetic resonance imaging and magnetic resonance arthrogram versus arthroscopy in the diagnosis of subscapularis tendon injury.
      ,
      • Neyton L.
      • Daggett M.
      • Kruse K.
      • Walch G.
      The hidden lesion of the subscapularis: Arthroscopically revisited.
      Adams et al.
      • Adams C.R.
      • Schoolfield J.D.
      • Burkhart S.S.
      Accuracy of preoperative magnetic resonance imaging in predicting a subscapularis tendon tear based on arthroscopy.
      found an excellent specificity of 100% in 52 SSC tears in 120 patients when diagnosed by radiologists. With a standardized approach to MRI reading, however, they found similar results between surgeons and radiologists regarding the accuracy in diagnosing SSC lesions, provided that the radiologists were musculoskeletal radiologists in majority.
      • Adams C.R.
      • Brady P.C.
      • Koo S.S.
      • et al.
      A systematic approach for diagnosing subscapularis tendon tears with preoperative magnetic resonance imaging scans.
      The best scenario for subscapularis tear detection consists of 2 musculoskeletal radiologists evaluating every preoperative MRI,
      • Pfirrmann C.W.
      • Zanetti M.
      • Weishaupt D.
      • Gerber C.
      • Hodler J.
      Subscapularis tendon tears: Detection and grading at MR arthrography.
      ,
      • Gyftopoulos S.
      • O’Donnell J.
      • Shah N.P.
      • Goss J.
      • Babb J.
      • Recht M.P.
      Correlation of MRI with arthroscopy for the evaluation of the subscapularis tendon: A musculoskeletal division’s experience.
      but such complex imaging procotols
      • Furukawa R.
      • Morihara T.
      • Arai Y.
      • et al.
      Diagnostic accuracy of magnetic resonance imaging for subscapularis tendon tears using radial-slice magnetic resonance images.
      ,
      • Meyer D.C.
      • Zimmermann S.M.
      • Wieser K.
      • Bensler S.
      • Gerber C.
      • Germann M.
      Lengthening of the subscapularis tendon as a sign of partial tearing in continuity.
      are rare in daily practice. The medicolegal aspect of imaging interpretation should also be considered in professional pathologies. Baptista et al.
      • Baptista E.
      • Malavolta E.A.
      • Gracitelli M.E.C.
      • et al.
      Diagnostic accuracy of MRI for detection of tears and instability of proximal long head of biceps tendon: An evaluation of 100 shoulders compared with arthroscopy.
      noted that an unsure radiologist or surgeon might not express their doubts and be elusive in the report, which can lead to the exclusion of most challenging cases, resulting in bias and overestimating diagnostic measures.
      Despite the high specificity reported, Adams et al.
      • Adams C.R.
      • Schoolfield J.D.
      • Burkhart S.S.
      Accuracy of preoperative magnetic resonance imaging in predicting a subscapularis tendon tear based on arthroscopy.
      found a sensitivity of 36% in the same series of 120 patients. This low sensitivity is consistent with the current literature.
      • Vinson E.N.
      • Wittstein J.
      • Garrigues G.E.
      • Taylor D.C.
      MRI of selected abnormalities at the anterior superior aspect of the shoulder: Potential pitfalls and subtle diagnoses.
      ,
      • Tung G.A.
      • Yoo D.C.
      • Levine S.M.
      • Brody J.M.
      • Green A.
      Subscapularis tendon tear: Primary and associated signs on MRI.
      The importance of using multiple imaging planes underlines the necessity of systematics approaches to improve sensitivity.
      • Gyftopoulos S.
      • O’Donnell J.
      • Shah N.P.
      • Goss J.
      • Babb J.
      • Recht M.P.
      Correlation of MRI with arthroscopy for the evaluation of the subscapularis tendon: A musculoskeletal division’s experience.
      ,
      • Ryu H.Y.
      • Song S.Y.
      • Yoo J.C.
      • Yun J.Y.
      • Yoon Y.C.
      Accuracy of sagittal oblique view in preoperative indirect magnetic resonance arthrography for diagnosis of tears involving the upper third of the subscapularis tendon.
      With a systematic approach to imaging and a combination of 7 criteria, Lin et al.
      • Lin L.
      • Yan H.
      • Xiao J.
      • et al.
      The diagnostic value of magnetic resonance imaging for different types of subscapularis lesions.
      observed an overall sensitivity of 82.2%; specificity of 92.1%; positive and negative predictive values of 87.1% and 88.9%, respectively; and accuracy of 88.2%. They did not perform an interobserver analysis allowing for comparison and reproducibility of the data collected from analyzing the preoperative imaging.
      The digitation sign by itself has a sensitivity of 74.3% and a specificity of 84.5%, based on shoulder-trained fellows’ analysis. However, our systematic approach, combining digitation sign and Adams et al.
      • Adams C.R.
      • Brady P.C.
      • Koo S.S.
      • et al.
      A systematic approach for diagnosing subscapularis tendon tears with preoperative magnetic resonance imaging scans.
      criteria, showed a significantly improved sensitivity of 89.2%. In our study, the sensitivity of Adams et al.
      • Adams C.R.
      • Brady P.C.
      • Koo S.S.
      • et al.
      A systematic approach for diagnosing subscapularis tendon tears with preoperative magnetic resonance imaging scans.
      criteria was higher (83.8%) than in the original cohort (73%),
      • Adams C.R.
      • Schoolfield J.D.
      • Burkhart S.S.
      Accuracy of preoperative magnetic resonance imaging in predicting a subscapularis tendon tear based on arthroscopy.
      possibly because of prevalence variations.
      Prevalence of SSC lesions, which influences sensitivity analysis, was higher in our population than previously reported,
      • Barth J.R.H.
      • Burkhart S.S.
      • De Beer J.F.
      The bear-hug test: A new and sensitive test for diagnosing a subscapularis tear.
      ,
      • Morag Y.
      • Jamadar D.A.
      • Miller B.
      • Dong Q.
      • Jacobson J.A.
      The subscapularis: Anatomy, injury, and imaging.
      ,
      • Adams C.R.
      • Schoolfield J.D.
      • Burkhart S.S.
      Accuracy of preoperative magnetic resonance imaging in predicting a subscapularis tendon tear based on arthroscopy.
      ,
      • Adams C.R.
      • Brady P.C.
      • Koo S.S.
      • et al.
      A systematic approach for diagnosing subscapularis tendon tears with preoperative magnetic resonance imaging scans.
      ,
      • Gyftopoulos S.
      • O’Donnell J.
      • Shah N.P.
      • Goss J.
      • Babb J.
      • Recht M.P.
      Correlation of MRI with arthroscopy for the evaluation of the subscapularis tendon: A musculoskeletal division’s experience.
      ,
      • Bennett W.F.
      Subscapularis, medial, and lateral head coracohumeral ligament insertion anatomy.
      with 56% having SSC tears. This can be explained by the attention of the senior surgeon to hidden lesions and systematically looking for SSC tears associated with biceps lesions by opening the biceps gutter.
      • Neyton L.
      • Daggett M.
      • Kruse K.
      • Walch G.
      The hidden lesion of the subscapularis: Arthroscopically revisited.
      Grade III or IV SSC tears according SFA
      • Toussaint B.
      • Barth J.
      • Charousset C.
      • et al.
      New endoscopic classification for subscapularis lesions.
      or Lafosse et al.
      • Lafosse L.
      • Lanz U.
      • Saintmard B.
      • Campens C.
      Arthroscopic repair of subscapularis tear: Surgical technique and results.
      classification are easily diagnosed, with 94.7% of cases presenting a positive digitation sign, 100% positive for Adams et al.
      • Adams C.R.
      • Brady P.C.
      • Koo S.S.
      • et al.
      A systematic approach for diagnosing subscapularis tendon tears with preoperative magnetic resonance imaging scans.
      criteria, and 100% for a combination of both signs, which is consistent with previous studies.
      • Foad A.
      • Wijdicks C.A.
      The accuracy of magnetic resonance imaging and magnetic resonance arthrogram versus arthroscopy in the diagnosis of subscapularis tendon injury.
      ,
      • Adams C.R.
      • Brady P.C.
      • Koo S.S.
      • et al.
      A systematic approach for diagnosing subscapularis tendon tears with preoperative magnetic resonance imaging scans.
      ,
      • Furukawa R.
      • Morihara T.
      • Arai Y.
      • et al.
      Diagnostic accuracy of magnetic resonance imaging for subscapularis tendon tears using radial-slice magnetic resonance images.
      ,
      • Gyftopoulos S.
      • O’Donnell J.
      • Shah N.P.
      • Goss J.
      • Babb J.
      • Recht M.P.
      Correlation of MRI with arthroscopy for the evaluation of the subscapularis tendon: A musculoskeletal division’s experience.
      Lin et al.
      • Lin L.
      • Yan H.
      • Xiao J.
      • et al.
      The diagnostic value of magnetic resonance imaging for different types of subscapularis lesions.
      also concluded that partial-thickness tears (less than one third of tendon width) were easily missed, and that there was increased sensitivity to the type of lesion, with a 100% sensitivity for type IV and V lesions according to Lafosse et al.
      • Lafosse L.
      • Lanz U.
      • Saintmard B.
      • Campens C.
      Arthroscopic repair of subscapularis tear: Surgical technique and results.
      We suggest using the digitation sign as a quick first-look tool during MRI analysis because of the difficulty in diagnosing small SSC lesions (Lafosse et al. I or II and SFA 1 or 2).
      • Shi L.L.
      • Mullen M.G.
      • Freehill M.T.
      • Lin A.
      • Warner J.J.P.
      • Higgins L.D.
      Accuracy of long head of the biceps subluxation as a predictor for subscapularis tears.
      ,
      • Adams C.R.
      • Schoolfield J.D.
      • Burkhart S.S.
      Accuracy of preoperative magnetic resonance imaging in predicting a subscapularis tendon tear based on arthroscopy.
      ,
      • Foad A.
      • Wijdicks C.A.
      The accuracy of magnetic resonance imaging and magnetic resonance arthrogram versus arthroscopy in the diagnosis of subscapularis tendon injury.
      ,
      • Furukawa R.
      • Morihara T.
      • Arai Y.
      • et al.
      Diagnostic accuracy of magnetic resonance imaging for subscapularis tendon tears using radial-slice magnetic resonance images.
      All other signs should be checked in a systematic procedure for meticulous analysis. The results of Lin et al.
      • Lin L.
      • Yan H.
      • Xiao J.
      • et al.
      The diagnostic value of magnetic resonance imaging for different types of subscapularis lesions.
      are in accordance with the idea that SSC tears can be diagnosed with several systematic criteria, obtaining the best sensitivity.
      Lack of homogeneity may be closer to the daily practice of most shoulder surgeons with patients being referred with different MRIs. Our results are consistent with other similar studies in the literature,
      • Smucny M.
      • Shin E.C.
      • Zhang A.L.
      • et al.
      Poor agreement on classification and treatment of subscapularis tendon tears.
      ,
      • Baptista E.
      • Malavolta E.A.
      • Gracitelli M.E.C.
      • et al.
      Diagnostic accuracy of MRI for detection of tears and instability of proximal long head of biceps tendon: An evaluation of 100 shoulders compared with arthroscopy.
      ,
      • Ryu H.Y.
      • Song S.Y.
      • Yoo J.C.
      • Yun J.Y.
      • Yoon Y.C.
      Accuracy of sagittal oblique view in preoperative indirect magnetic resonance arthrography for diagnosis of tears involving the upper third of the subscapularis tendon.
      however, showing that the analysis of MRIs depends strongly on the observer. In contrast, our systematic approach to MRI interpretation is reproducible (k= 0.640) and can be used with standard MRI protocols of different institutions in daily practice. This protocol was designed with shoulder-trained fellows and can be helpful for young surgeons in their preoperative evaluation. Our higher SSC tear prevalence (56%) may also reflect a systematic arthroscopic evaluation for hidden lesions.

      Limitations

      This study had several limitations. First, the analysis was retrospective. There was an 18-month delay between MRI and surgery. Furthermore, there were only 3 shoulder trained fellows from different institutions but no radiologist interpreting the MRIs, and there was no intraobserver agreement analysis. Different MRI protocols were used in each radiology institution, which might impair MRI analysis. Our interobserver analysis reveals a globally poor interevaluation between the 3 observers.

      Conclusions

      Preoperative systematic MRI evaluation by shoulder surgeons can diagnose subscapularis lesions by using the digitation sign in the coronal plane with Adams et al.
      • Adams C.R.
      • Brady P.C.
      • Koo S.S.
      • et al.
      A systematic approach for diagnosing subscapularis tendon tears with preoperative magnetic resonance imaging scans.
      criteria, leading to good sensitivity. This easy-to-apply sign can be helpful in the initial MRI evaluation in the coronal plane, with improved sensitivity when combined with a systematic approach.

      Acknowledgments

      FORE (Foundation for Research and Teaching in Orthopaedics, Sports Medicine, Trauma and Imaging in the Musculoskeletal System), grant number FORE 2021-13.

      Supplementary Data

      References

        • Gerber C.
        • Krushell R.J.
        Isolated rupture of the tendon of the subscapularis muscle. Clinical features in 16 cases.
        J Bone Joint Surg Br. 1991; 73: 389-394
        • Hegedus E.J.
        • Goode A.
        • Campbell S.
        • et al.
        Physical examination tests of the shoulder: A systematic review with meta-analysis of individual tests.
        Br J Sports Med. 2008; 42: 80-92
        • Barth J.R.H.
        • Burkhart S.S.
        • De Beer J.F.
        The bear-hug test: A new and sensitive test for diagnosing a subscapularis tear.
        Arthroscopy. 2006; 22: 1076-1084
        • Burkhart S.S.
        • Brady P.C.
        Arthroscopic subscapularis repair: Surgical tips and pearls A to Z.
        Arthroscopy. 2006; 22: 1014-1027
        • Teefey S.A.
        • Rubin D.A.
        • Middleton W.D.
        • Hildebolt C.F.
        • Leibold R.A.
        • Yamaguchi K.
        Detection and quantification of rotator cuff tears. Comparison of ultrasonographic, magnetic resonance imaging, and arthroscopic findings in seventy-one consecutive cases.
        J Bone Joint Surg Am. 2004; 86: 708-716
        • Smucny M.
        • Shin E.C.
        • Zhang A.L.
        • et al.
        Poor agreement on classification and treatment of subscapularis tendon tears.
        Arthroscopy. 2016; 32: 246-251.e1
        • Eren I.
        • Ozben H.
        • Gunerbuyuk C.
        • et al.
        Rotator cuff tear characteristics: How comparable are the pre-operative MRI findings with intra-operative measurements following debridement during arthroscopic repair?.
        Int Orthop. 2019; 43: 1171-1177
        • Shi L.L.
        • Mullen M.G.
        • Freehill M.T.
        • Lin A.
        • Warner J.J.P.
        • Higgins L.D.
        Accuracy of long head of the biceps subluxation as a predictor for subscapularis tears.
        Arthroscopy. 2015; 31: 615-619
        • Vinson E.N.
        • Wittstein J.
        • Garrigues G.E.
        • Taylor D.C.
        MRI of selected abnormalities at the anterior superior aspect of the shoulder: Potential pitfalls and subtle diagnoses.
        AJR Am J Roentgenol. 2012; 199: 534-545
        • Arai R.
        • Mochizuki T.
        • Yamaguchi K.
        • et al.
        Functional anatomy of the superior glenohumeral and coracohumeral ligaments and the subscapularis tendon in view of stabilization of the long head of the biceps tendon.
        J Shoulder Elbow Surg. 2010; 19: 58-64
        • Morag Y.
        • Jamadar D.A.
        • Miller B.
        • Dong Q.
        • Jacobson J.A.
        The subscapularis: Anatomy, injury, and imaging.
        Skeletal Radiol. 2011; 40: 255-269
        • Yoo J.C.
        • Rhee Y.G.
        • Shin S.J.
        • et al.
        Subscapularis tendon tear classification based on 3-dimensional anatomic footprint: A cadaveric and prospective clinical observational study.
        Arthroscopy. 2015; 31: 19-28
        • Adams C.R.
        • Schoolfield J.D.
        • Burkhart S.S.
        Accuracy of preoperative magnetic resonance imaging in predicting a subscapularis tendon tear based on arthroscopy.
        Arthroscopy. 2010; 26: 1427-1433
        • Foad A.
        • Wijdicks C.A.
        The accuracy of magnetic resonance imaging and magnetic resonance arthrogram versus arthroscopy in the diagnosis of subscapularis tendon injury.
        Arthroscopy. 2012; 28: 636-641
        • Godenèche A.
        • Nové-Josserand L.
        • et al.
        • French Society for Arthroscopy (SFA)
        Relationship between subscapularis tears and injuries to the biceps pulley.
        Knee Surg Sports Traumatol Arthrosc. 2017; 25: 2114-2120
        • Adams C.R.
        • Brady P.C.
        • Koo S.S.
        • et al.
        A systematic approach for diagnosing subscapularis tendon tears with preoperative magnetic resonance imaging scans.
        Arthroscopy. 2012; 28: 1592-1600
        • Furukawa R.
        • Morihara T.
        • Arai Y.
        • et al.
        Diagnostic accuracy of magnetic resonance imaging for subscapularis tendon tears using radial-slice magnetic resonance images.
        J Shoulder Elbow Surg. 2014; 23: e283-e290
        • Gasbarro G.
        • Neyton L.
        The arthroscopic “montgolfier double-row knotless” rotator cuff repair technique.
        Arthrosc Tech. 2019; 8: e669-e674
        • Lafosse L.
        • Lanz U.
        • Saintmard B.
        • Campens C.
        Arthroscopic repair of subscapularis tear: Surgical technique and results.
        Orthop Traumatol Surg Res. 2010; 96: S99-S108
        • Toussaint B.
        • Barth J.
        • Charousset C.
        • et al.
        New endoscopic classification for subscapularis lesions.
        Orthop Traumatol Surg Res. 2012; 98: S186-S192
        • Amouyel T.
        • Le Moulec Y.P.
        • Tarissi N.
        • Saffarini M.
        • Courage O.
        Arthroscopic biceps tenodesis using interference screw fixation in the bicipital groove.
        Arthrosc Tech. 2017; 6: e1953-e1957
        • Lo I.K.Y.
        • Burkhart S.S.
        The comma sign: An arthroscopic guide to the torn subscapularis tendon.
        Arthroscopy. 2003; 19: 334-337
        • Neyton L.
        • Daggett M.
        • Kruse K.
        • Walch G.
        The hidden lesion of the subscapularis: Arthroscopically revisited.
        Arthrosc Tech. 2016; 5: e877-e881
        • Denard P.J.
        • Jiwani A.Z.
        • Lädermann A.
        • Burkhart S.S.
        Long-term outcome of a consecutive series of subscapularis tendon tears repaired arthroscopically.
        Arthroscopy. 2012; 28: 1587-1591
        • Walch G.
        • Nove-Josserand L.
        • Levigne C.
        • Renaud E.
        Tears of the supraspinatus tendon associated with “hidden” lesions of the rotator interval.
        J Shoulder Elbow Surg. 1994; 3: 353-360
        • Baptista E.
        • Malavolta E.A.
        • Gracitelli M.E.C.
        • et al.
        Diagnostic accuracy of MRI for detection of tears and instability of proximal long head of biceps tendon: An evaluation of 100 shoulders compared with arthroscopy.
        Skeletal Radiol. 2019; 48: 1723-1733
        • Li X.X.
        • Schweitzer M.E.
        • Bifano J.A.
        • Lerman J.
        • Manton G.L.
        • El-Noueam K.I.
        MR evaluation of subscapularis tears.
        J Comput Assist Tomogr. 1999; 23: 713-717
        • Pfirrmann C.W.
        • Zanetti M.
        • Weishaupt D.
        • Gerber C.
        • Hodler J.
        Subscapularis tendon tears: Detection and grading at MR arthrography.
        Radiology. 1999; 213: 709-714
        • Tung G.A.
        • Yoo D.C.
        • Levine S.M.
        • Brody J.M.
        • Green A.
        Subscapularis tendon tear: Primary and associated signs on MRI.
        J Comput Assist Tomogr. 2001; 25: 417-424
        • Zhang H.
        • Zhang Q.
        • Li Z.L.
        Coracohumeral index and coracoglenoid inclination as predictors for different types of degenerative subscapularis tendon tears.
        Int Orthop (SICOT). 2019; 43: 1909-1916
        • Gyftopoulos S.
        • O’Donnell J.
        • Shah N.P.
        • Goss J.
        • Babb J.
        • Recht M.P.
        Correlation of MRI with arthroscopy for the evaluation of the subscapularis tendon: A musculoskeletal division’s experience.
        Skeletal Radiol. 2013; 42: 1269-1275
        • Meyer D.C.
        • Zimmermann S.M.
        • Wieser K.
        • Bensler S.
        • Gerber C.
        • Germann M.
        Lengthening of the subscapularis tendon as a sign of partial tearing in continuity.
        J Shoulder Elbow Surg. 2016; 25: 31-37
        • Ryu H.Y.
        • Song S.Y.
        • Yoo J.C.
        • Yun J.Y.
        • Yoon Y.C.
        Accuracy of sagittal oblique view in preoperative indirect magnetic resonance arthrography for diagnosis of tears involving the upper third of the subscapularis tendon.
        J Shoulder Elbow Surg. 2016; 25: 1944-1953
        • Lin L.
        • Yan H.
        • Xiao J.
        • et al.
        The diagnostic value of magnetic resonance imaging for different types of subscapularis lesions.
        Knee Surg Sports Traumatol Arthrosc. 2016; 24: 2252-2258
        • Bennett W.F.
        Subscapularis, medial, and lateral head coracohumeral ligament insertion anatomy.
        Arthroscopy. 2001; 17: 173-180