Radiographic greater tuberosity spurs and narrow acromiohumeral intervals are associated with advanced retraction of the supraspinatus tendon in patients with symptomatic rotator cuff tears

BACKGROUND: Degenerative signs on shoulder radiographs, including spur formation and narrow acromiohumeral intervals (AHIs), have been recognized as indicative of atrophic and fat-infiltrated rotator cuff muscles. Past studies have demonstrated that patients with poor quality muscles are prone to retraction of the supraspinatus tendon and failure to repair. However, the association between radiographic signs and tendon retraction has never been elucidated in previous literature. The present study aimed to investigate the association between the degenerative signs on shoulder radiographs and the severity of supraspinatus retraction. METHODS: Images of 67 individuals, who had undergone an arthroscopic rotator cuff repair, were retrospectively reviewed. The greater tuberosity (GT) morphology, subacromial spur, AHI, and acromial thickness were evaluated on the radiographs, whereas the retraction of the supraspinatus tendon was assessed via an MRI in accordance with the Patte classification. Simple regression analyses between the radiographic signs and Patte stages were performed, and factors reaching statistical significance were then included in the multiple ordinal logistic regression. Statistically significant predictors from the multiple regression analysis were constructed into combinations, for which the sensitivity and specificity were calculated. RESULTS: The GT morphology (P = .004), AHI (P = .083), subacromial spur (P = .008), and age (P = .004) were associated with supraspinatus retraction in the simple regression analyses. These four parameters were incorporated into the multiple ordinal logistic regression, where the GT spur (adjusted odds ratio 8.63, 95% confidence interval 2.16-34.53, P = .002) and AHI (AOR 0.79, 95% CI 0.63-0.98, P = .032) were demonstrated to be predictive of the Patte stage of supraspinatus retraction. The acromial spur implied a higher risk of severe retraction although this finding was not statistically significant (AOR 2.89, 95% CI 0.90-9.29, P = .075). The presence of concurrent GT spur and narrow AHI was highly specific (sensitivity 27.3% / specificity 91.1%) for advanced supraspinatus retraction. CONCLUSION: The presence of a radiographic GT spur, narrow AHI, and subacromial spur indicated advanced retraction of the supraspinatus tendon. When patients with clinical suspicion of rotator cuff tear present with combinations of these radiographic signs, a prompt MRI examination and a referral to a shoulder specialist are recommended.