Sex Hormone Supplementation and Rotator Cuff Repair: A Preliminary Randomized Trial - Project Summary/Abstract Rotator cuff tears (RCTs) are among the most common musculoskeletal complaints and are becoming more common. These injuries cost the US health care system $5 billion dollars annually. Prospective randomized and controlled studies have demonstrated that rotator cuff repair (RCR) is indicated for small- and medium-sized tears. Over 500,000 RCRs are performed in the US annually. However, after RCR, healing fails to occur in >25% of patients. Understanding how to improve healing is a critical barrier to success. There is near universal agreement that improving the biology of tendon healing is the key to improving healing. Our prior research suggests Sex Hormone Deficiency (SHD, i.e. hypogonadism) plays a role in RCR healing failure. The research described in the current proposal is the next step towards translating our promising and compelling preclinical and laboratory findings into improved clinical care of patients with RCTs. SHD can be treated with hormone therapy (HT), which is widely utilized, well-tolerated, inexpensive, and FDA approved. Thus, we propose a phase II study to test preliminary efficacy and feasibility. Within aim 1, we will estimate the preliminary efficacy of systemic HT through a randomized, placebo-controlled, double-blinded clinical trial. Hypogonadal men aged 40-80 with SHD will be included. Postoperatively we will evaluate: A. RCR outcomes and B. RCR healing. We hypothesize that outcomes and healing will be better in the HT group than the control group. Within aim 2, we will determine the feasibility of studying systemic HT in the setting of RCR. Although there is extensive clinical experience with HT in human males with SHD, there is almost none in a setting of RCR surgery. To determine the feasibility of a future, larger, multi-center, randomized clinical trial, we will measure the following within the context of the study described in Aim 1: A. recruitment and retention rates, B. patient compliance, C. hormonal response, and D. adverse effects. The expected outcome of the work proposed is demonstration of the preliminary efficacy and feasibility of HT in human males with SHD undergoing RCR. If this intervention is effective and feasible, then a future, larger, well- powered, multi-centered randomized clinical trial with longer follow-up would be warranted. Such a study could improve the treatment of people with RCTs, thereby decreasing a source of significant disability.