there was an unacceptably high adverse event rate in the treatment group.

The investigators hypothesized that radiation therapy could be safely administered acutely after elbow trauma, and it would decrease the number of patients that would require surgical excision of heterotopic ossification.

A multi-institutional, prospective randomized clinical trial will be employed to determine if single dose, limited field radiation therapy (XRT) will prevent post-traumatic heterotopic ossification (HO) after open reduction internal fixation of intra-articular distal humerus fractures and fracture-dislocations of the elbow and to assess function of the elbow after XRT and no XRT. Patients will be randomly assigned to one of the two groups(XRT/treatment or no XRT/control) by a computer-generated randomization schedule. Assignment will be in a ratio of 1:1 in a complete block design of 10. Each clinical site will be provided with a separate randomization assignment for each study participant. The treating surgeon and patient will be blinded to group assignment until after operative treatment. Clinical and radiographic assessments at 6 weeks, 3 months and 6 months post-operatively will be performed. The primary clinical outcome will be the Mayo elbow performance score which measures pain, stability, function and motion. Motion parameters (flexion, extension, pronation and supination) will be performed at each data collection point. Primary radiographic outcome will be the presence of heterotopic ossification by plain radiographs of the elbow in the antero-posterior and lateral planes at 6 weeks, 3 months, and 6 months post-operatively. Further imaging (radiograph or CT) will be obtained past the 6-month interval if deemed necessary by the treating physician,or if fracture union was not achieved at 6 months. The presence of HO will be quantified by radiograph. All adverse events will be documented. The trial will be monitored periodically by the Safety Monitor at least twice a year to ensure protocol compliance and address safety issues.

Inclusion Criteria:

• Skeletally mature patients with minimum age of 18 years and maximum age of 65.
• Patients deemed appropriate for operative intervention by the treating physician.
• Distal humerus intra-articular fractures (types 13-C1, C2, and C3), with or without proximal radius/ulna fractures - open or closed.
• Fracture-dislocations of the elbow (ulno-humeral dislocation associated with proximal ulna and/or radius fractures) - open or closed.

Exclusion Criteria:

• Head injury, quantified by Glasgow Coma Score (GCS) < 13 at time of consent for operative intervention.
• Burns > 20% Total Body Area (TBA) or involving the operative site.
• Patients with spinal cord injury affecting the upper extremities will be excluded.
• Open fractures which cannot be closed primarily within 72 hours of initial operative intervention.
• Patients with estimated life expectancy of less than one year due to preexisting condition.