Pre-operative transverse tendon thickness in small and mid-sized rotator cuff tears does not affect clinical outcomes after arthroscopic repair

Introduction: Previous studies on rotator cuff tears have examined both clinical and radiographic parameters which may influence post-operative clinical outcomes. While rotator cuff tears are frequently classified by size or depth, there is currently no literature available examining the thickness of the remnant tendon, and its impact on post-operative outcomes. We hypothesize that decreased pre-operative transverse tendon thickness will result in poorer post-operative clinical outcomes. Methods: We prospectively recruited patients who underwent arthroscopic repair of small to medium full-thickness rotator cuff tears. These patients were followed up for a minimum of 2 years post-operatively. Basic biodata, as well as Visual Analog Scale (VAS) for pain, Constant-Murley Score (CMS), UCLA Shoulder Score (USS), and Oxford Shoulder Score (OSS) at 3 different time points (pre-operatively, 1 year post-operatively, and 2 years post-operatively) were collected. Transverse tendon thickness was measured by independent blinded radiologists on pre-operative ultrasonographic images. Wilcoxon signed-rank test was used to compare outcome scores and multivariable robust linear model was fitted to assess the effect of transverse tendon thickness on post-operative scores. Results: A total of 63 patients were enrolled in this study, predominantly female (65%) and had a median age of 72 years. Pre-operatively, the median transverse cuff thickness was 5.0 mm and median tear size was 1.4 cm. The median VAS at preoperative was 7, which reduced to 0 at 2 year post-operative, indicating statistically significant improvement in pain levels (p < 0.001). Statistically significant improvement in shoulder function measured by CMS, UCLA score and OSS were also seen over time (p < 0.001). Robust regression analysis revealed that transverse cuff thickness had no statistically significant effect on VAS (p = 0.99), CMS (p = 0.84), UCLA score (p = 0.22), and OSS scores (p = 0.73) at 2 years postoperatively. Discussion: Pre-operative transverse tendon thickness of small- to mid-sized supraspinatus tears does not influence clinical outcomes after arthroscopic repair. Differences in transverse tendon thickness may have an association with tendon healing but do not translate to an association with post-operative outcomes in terms of pain, function, and patient-reported outcome measures.