The aim of this study was to evaluate the relationship between the tear size and the short-term clinical outcome of rotator cuff reconstruction. The hypothesis was that the size of the rotator cuff tear has a direct negative correlation with post-operative clinical outcome.

Five hundred and seventy-six consecutive shoulders with a primarily arthroscopically treated full-thickness rotator cuff tear were followed up. Rotator cuff tear size (anteroposterior dimension) was measured intraoperatively with an arthroscopic measuring probe. The Constant score was used as an outcome measure and was measured pre-operatively and 1-year post-operatively.

Five hundred and sixty-nine patients (99 %) were available for 1-year follow-up. The mean age of patients was 59.6 (SD 9.6) years. There were 225 (40 %) female and 344 (60 %) male patients. The mean size of the rotator cuff tear was 25 mm (SD 18). The mean pre- and post-operative Constant score was 52.3 (SD 17.4) and 74.2 (SD 15.5), respectively (p < 0.0001). The intraoperatively detected tear size correlated significantly with the pre-operative Constant score (r = −0.20, p < 0.0001). Furthermore, there was even stronger and significant correlation between the tear size and the final post-operative Constant score (r = −0.36, p < 0.0001). The correlation was similar between the genders, but the Constant scores were significantly lower in women (p < 0.0001). The lowest scores were detected in tears with infraspinatus tendon involvement.

The size of the rotator cuff tear linearly correlates with the Constant scores both pre- and post-operatively. The outcome of rotator cuff reconstruction is strongly related to the intraoperatively detected tear size.