Management of massive rotator cuff tears is a therapeutic challenge in patients younger than 65 years, particularly if still working. According to our hypothesis, choice of the most appropriate treatment option mainly depends on the patient’s functional status and on two predictive factors: height of the subacromial space and fatty muscle infiltration. This is a retrospective, multicenter study of a series of 296 patients younger than 65 years, including 176 males and 120 females with extensive or massive cuff tear. Patients had loss of elevation or external rotation or both in 162 cases. Four types of management of massive rotator cuff tear were performed in this study: anatomical watertight repairs, palliative treatments and partial repairs, watertight repairs using flaps or cuff prostheses and reverse shoulder prostheses. At follow-up, the Constant score (65.6±3.4) and active elevation (147.7°±32°) had significantly improved. Active external rotation with elbow at the side, and acromiohumeral interval (AHI) were unchanged. Work-related injuries, previous surgeries and complications were correlated with a poorer Constant score. At follow-up, the anatomical repair sub-group had a significantly better Constant score than the three other treatment groups but involved patients with unchanged AHI and a low degree of fatty infiltration of the infraspinatus muscle. The reverse shoulder prostheses sub-group showed better outcomes in terms of function benefits. The presence of a long biceps was correlated with the use of a palliative treatment. In the light of the results and literature, an approach to treatment is suggested related to the functional capacity of patients, the AHI and the degree of fatty infiltration of the infraspinatus and subscapularis muscles.