Objectives: This study aims to identify the forelock sign of partial tears of the subscapularis and to compare the incidences of this sign and air bag sign.
Patients and methods: One hundred and twenty patients (39 males, 81 females; mean age 51.3 years; range, 25 to 79) diagnosed as isolated subscapularis tear or isolated supraspinatus tear from among patients who underwent shoulder arthroscopy between January 2013 and January 2016 were divided into four groups of 30 patients each as the subscapularis tear (group 1), full-thickness supraspinatus tear (group 2), bursal-side supraspinatus tear (group 3), and articular-side supraspinatus tear (group 4) groups. All patients had video records of their operation. The integrity of the long head of biceps tendon (LHBT), Lafosse classification of the subscapularis tear, and the incidence of the forelock and air bag signs were evaluated.
Results: The incidence of the air bag sign in group 1 was 10% and that of the forelock sign was 60%. The forelock sign was significantly more frequent in group 1 than in the other groups (odds ratio 10.46: 3.9-27.8 with 95% confidence interval) and the air bag sign (p<0.001). The LHBT was mostly pathologic in this group, which was also statistically significant (p<0.01). The incidence of the forelock sign in group 1 was similar in each LHBT pathology and Lafosse subgroups.
Conclusion: The forelock sign identified in this study was significantly frequent (60%) in partial subscapularis tendon tears with strong inter- and intra-observer consistency while the air bag sign was rare (10%). The LHBT disorders were strongly associated with subscapularis tears; however, the forelock sign was not an indicator of the condition of the LHBT and type of partial subscapularis tendon tear according to the Lafosse classification.