The Journal of Bone and Joint Surgery December 1 2007, Volume 89, Issue 12 M.M. Lefevre-Colau, MD, PhD1, A. Babinet, MD2, F. Fayad, MD, MS2, J. Fermanian, MD, PhD3, P. Anract, MD2, A. Roren, PT2, J. Kansao, MD2, M. Revel, MD, PhD2 and S. Poiraudeau, MD, PhD2 Disclosure: In support of their research for or preparation of this work, one or more of the authors received, in any one year, outside funding or grants in excess of $10,000 from the Department of Clinical Research of the Assistance Publique-Hopitaux de Paris (APHP). Neither they nor a member of their immediate families received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which the authors, or a member of their immediate families, are affiliated or associated. Background: There have been few randomized controlled trials evaluating nonoperative treatment of proximal humeral fractures. To investigate shortening the period of dependence, we assessed the feasibility and efficacy of early mobilization of the shoulder (within three days after the fracture) in comparison with those of conventional three-week immobilization followed by physiotherapy. Methods: We randomly assigned seventy-four patients with an impacted proximal humeral fracture to receive early passive mobilization or conventional treatment. The primary outcome was the overall shoulder functional status (as measured with the Constant score) at three months. The secondary outcomes were the Constant score at six weeks and at six months, the change in pain (on a visual analog scale), and the active and passive range of motion. Results: At three months and at six weeks, the early mobilization group had a significantly better Constant score than did the conventional-treatment group (between-group difference, 9.9 [95% confidence interval, 1.9 to 17.8] [p = 0.02] and 10.1 [95% confidence interval, 2.0 to 18.1] [p = 0.02], respectively) and better active mobility in forward elevation (between-group difference, 12.0 [95% confidence interval, 1.7 to 22.4] [p = 0.02] and 28.1 [95% confidence interval, 7.1 to 49.1] [p = 0.01], respectively). At three months, the early mobilization group had significantly reduced pain compared with the conventional-treatment group (between-group difference, 15.7 [95% confidence interval, 0.52 to 30.8] [p = 0.04]). No complications in displacement or nonhealing were noted. Conclusions: Early mobilization for impacted nonoperatively treated proximal humeral fractures is safe and is more effective for quickly restoring the physical capability and performance of the injured arm than is conventional immobilization followed by physiotherapy. Level of Evidence: Therapeutic Level I. See Instructions to Authors for a complete description of levels of evidence.