Inclusion Criteria:

• * Patient is 18 years of age or older.
• * Patient must have signed Institutional Review Board (IRB)/Ethics Committee (EC)-approved informed consent.
• * Patient is a candidate for primary or revision total elbow arthroplasty, based on symptoms including at least one of the following:
• * Elbow joint destruction which significantly compromises daily living activities
• * Post-traumatic lesions or bone loss contributing to elbow instability
• * Ankylosed joints, especially cases of bilateral ankylosis from causes other than active sepsis
• * Advanced rheumatoid arthritis, post-traumatic, or degenerative arthritis with incapacitating pain
• * Instability or loss of motion when the degree of joint or soft tissue damage precludes reliable osteosynthesis
• * Acute comminuted articular fracture of elbow joint surfaces that precludes less radical procedures, including 13-C3 fractures of the distal humerus
• * Patient is willing and able to complete scheduled follow-up evaluations as defined by the protocol.
• Additional Retrospective Arm Inclusion Criteria
• * Patient must have undergone a total elbow replacement with the Nexel system between July 2013 and the date of the site initiation visit.
• * Patient information available for each retrospective patient must, at minimum, include preoperative demographic information, preoperative physical exam information, the index surgery operative report, and details of the devices implanted.

Exclusion Criteria:

• * Patient has a currently active or history of repeated local infection at the surgical site.
• * Patient has a current major infection distant from the operative site.
• * Patient has a history of prior sepsis.
• * Patient suffers from paralysis or dysfunctional neuropathy at the elbow joint.
• * Patient has significant ipsilateral hand dysfunction.
• * Patient has excessive scarring near the surgical site, which could prevent adequate soft tissue coverage.
• * Patient participates in daily activities that may cause significant stress to an implanted device such as heavy labor, torsional stress, and/or competitive sports.
• * Patient is a prisoner.
• * Patient is mentally incompetent or unable to understand what participation in the study entails.
• * Patient is a known alcohol or drug abuser.
• * Patient is anticipated to be non-compliant.
• * Patient is known to be pregnant.