Aptis PRUJ Prosthesis for the Treatment of Patients With Proximal Radial Ulna Joint Disorders.

Inclusion Criteria: * In order to be eligible to participate in this study, subjects must meet all of the following criteria: 1. Patient is skeletally mature and under 85 years of age. 2. Patient has a painful, unstable radial head due to degeneration or post-traumatic disabilities presenting pain, crepitation, and decreased motion at the radiohumeral and/or proximal radioulnar joint and is otherwise 3. Patients willing and able to understand and sign the informed consent. In the opinion of the Investigator, the patient has the understanding and willingness to comply with all study requirements including the post-operative rehabilitation and follow-up visits per protocol. Exclusion Criteria: * 1\. Inadequate bone stock or soft tissue coverage 2. Patients with severe humeral/ulnar arthritis, defined as: 1. Pain at terminal flexion/extension 2. Pain throughout ROM with loss of motion in terminal flexion and/or extension 3. Patients with an allergy to the implant materials 4. Active systemic infection or infection at the site of surgery 5. Physical interference with or by other prostheses during implantation or use 6. Have a Body Mass Index (BMI) greater than 35 kg/m2 7. Have any mental or psychological disorder that would impair the ability to complete the study questionnaires 8. Have significant comorbidities or conditions associated with high-risk for surgical or anesthetic survival (e.g., renal failure, peripheral vascular disease, unstable cardiac disease, poorly controlled diabetes, immunosuppression, etc.) 9. Have any medical condition or other circumstances that might interfere with the ability to return for follow-up visits in the judgment of the Investigator, including any systemic illness, neuromuscular, neurosensory, or musculoskeletal deficiency that would render the subject unable to perform appropriate post-operative rehabilitation 10. Have any condition which, in the judgment of the Investigator, would preclude adequate evaluation of the device's safety and performance 11. Skin, bone, circulatory and/or neurological deficiency at or affecting the implantation site 12. Prisoners 13. Patients on chronic corticosteroid or non-steroidal anti-inflammatory therapy 14. Women who are pregnant or breast-feeding or are planning to become pregnant during the study. 15\. Patients with a documented history of uncontrolled diabetes. 16. Patients with known allergies against anesthesia. 17. Patients with a history of or current drug and/or alcohol abuse 18. Patients unlikely to cooperate or are legally incompetent. 19. Patients with legal involvement, including an active claim for workman's compensation, or any other issue that would hinder completion of the two-year follow period. 20\. Patients who are participating or have participated in any other study involving an investigational drug or device within the past 3 months. Intra-operative Exclusion Criteria Subjects who meet any of the following intra-operative screening criteria will be excluded from participation in this study: * A proximal radio ulnar joint that cannot be reduced intraoperatively * Inadequate bone quality that would allow for implant placement * Not enough radius bone proximally for device implantation