The statistical analysis of results obtained with splinting treatment of finger and hand stiffness, and derived from a series of 635 motion range measurements taken on 249 hand joints, provided us with sufficient data to identify the various factors likely to have an impact on the therapeutic outcome. A mean increase of 25.8% in the range of movements is enough to justify the use of orthosis, although this figure actually varies substantially with the patient's age, the duration of the stiffness, the latter's degree and origin, the joint involved, and the duration of the orthotic treatment. An analysis of the time factor enabled us to establish the date beyond which changes for recovery are quite limited, whereby allowing to schedule surgical mobilization.