Arm 1- Injured Patients  Inclusion Criteria:  Any patient treated in our hospital system from initial IRB approval until we reach our enrollment quota that are diagnosed with HO, hip fracture, midshaft/distal femur fracture, humerus fracture, proximal radius fracture, and elbow dislocation/fracture. This includes patients in all age groups and of all genders. Patients with a diagnosis of HO, hip fracture, midshaft/distal femur fracture, humerus fracture, proximal radius fracture, or elbow fracture must be receiving operative treatment for their injury. Patients with concurrent trauma will be grouped into a sub-analysis.  Exclusion Criteria:  Patients with pathologic fractures. Non-operative patients other than elbow dislocation patients Pregnant Women Patients who do not intend to follow-up at Vanderbilt  Arm 2- Healthy Volunteers  Inclusion Criteria:  Volunteers (male or female) between ages of 18-70 Weight greater than 110lbs  Exclusion Criteria:  Chronic medical conditions such as diabetes, hypertension, high cholesterol, rheumatologic disorders, infections, etc. History of recent trauma or burn injury Recent inpatient admission within the last year Pregnant females or people on hormone replacement therapy People on any anticoagulant medication or NSAIDS