End-stage ankle arthritis (ESAA) is a debilitating condition associated with severe pain, dysfunction, and reduced quality of life. Many patients with ESAA have difficulty walking for even 100 feet or up a single flight of stairs. Patients seeking surgery for ESAA have two primary treatment options: ankle arthrodesis (i.e., ankle fusion) and ankle arthroplasty (i.e., ankle replacement). Few studies have directly compared the effectiveness of these two procedures, and no randomized controlled trials (RCTs) have been performed.

The investigators will compare the following in subjects undergoing ankle arthrodesis and ankle arthroplasty before surgery, and post-surgery at 3 and 6 months, and on an annual basis up to ten years.

1. Overall physical function and ankle specific function
2. Ankle pain intensity and interference with activities
3. Activity levels
4. Overall general health
5. Post-surgical complication rates

The investigators will also identify prognostic factors that are predictive of higher physical function, ankle specific function, reduced pain, improved general health, and overall patient satisfaction.

From study inception until March 2014, the investigators conducted a multi-site randomized controlled trial (RCT) comparing the effectiveness of ankle arthrodesis and ankle arthroplasty over a 2-year follow-up period. The study used a modified Comprehensive Cohort Design. Subjects unwilling to randomize to surgery could still participate in the study by entering into the preference cohort and select surgery in consultation with their surgeon.

By March 2014, no subjects had entered into the randomized cohort. The Data and Safety Monitoring Board (DSMB) recommended stopping recruitment in the randomized arm of the study since no subjects were willing to randomize to surgery. All patients were enrolled in the preference cohort and selected arthrodesis or arthroplasty. Despite the change in study design, the objectives remain unchanged.

Inclusion Criteria:

1. Diagnosis of ankle arthritis
2. Failed conservative care and deemed a surgical candidate
3. Adult patients between 21 and 89 years of age
4. Ambulatory but whose primary impediment to pain-free ambulation is ankle arthritis

Exclusion Criteria:

1. Recent surgical, neurological, metabolic, or lower limb musculoskeletal problem that might impair the ambulation measures in the study such as severe knee or hip osteoarthritis
2. Complicated procedures requiring multiple corrections
3. Inflammatory arthritis with multi-focal disease (i.e. arthritis that affects multiple parts of the body)
4. Inadequate cognitive or language function to consent to participate
5. Unable or unwilling to participate in clinic follow-ups and/or remote follow-ups for 24 months after surgery
6. Unwilling or unable to comply with postoperative management program
7. Lack of a telephone number or stable mailing address

Subjects are recruited from surgical foot and ankle orthopedic clinics at the participating study sites.