Treatment Outcomes for Ankle Arthritis

Project Objective:

Ankle osteoarthritis is characterized by joint pain, tenderness, limitation of movement, and variable degrees of inflammation. These factors combined and left untreated will severely limit a person's mobility and willingness to participate in activities. Two common surgical procedures chosen to alleviate pain and to increase mobility are ankle arthrodesis (ankle fusion) and arthroplasty (ankle replacement). Success rates for these procedures are variable and the amount of information available regarding long-term follow-up is limited. The extent to which a person is able and willing to move around the world is often an indicator of his/her condition. The proposed study will examine walking activity levels, and any difference in activity, in patients immediately before and after undergoing surgical treatment for ankle arthritis.

Successfully regaining motility is a priority for patients electing to have surgical treatment for ankle arthritis. A difference in activity levels would indicate an important outcome difference between surgical procedures.

Research Plan:

The investigators propose a mobility outcome study with up to 500 ankle osteoarthritis subjects who will undergo corrective surgery.

Methodology:

The investigators propose a mobility outcome study with a total of up to 500 ankle osteoarthritis subjects before and after surgery over the three years of the study. Ankle arthritis subjects will be recruited from patients at the VA Puget Sound Health Care System (Seattle, WA), Harborview Medical Center (Seattle, WA), Orthopedic + Fracture Specialists (Portland, OR), Orthopaedic Associates of Michigan (Grand Rapids, MN), and Twin Cities Orthopedics (Edina, MN) who have been diagnosed with end stage ankle arthrosis, are ambulatory, speak English, are cognitively intact, and between the ages of 18-80. Recruitment, informed consent procedures and the experimental protocol will be approved by the Institutional Review Board (IRB) at each study site.

Since there is no clinical equipoise it would be unethical to randomize treatment at this time. This project is an observational study of the outcomes following two common treatments: Ankle arthrodesis (fusion) and ankle arthroplasty (total ankle joint replacement). The outcomes will be assessed in two domains:

Functional domain: Each subject's functional status will be determined by the Musculoskeletal Function Assessment (MFA) and the SF-36 general health survey. The MFA is a written questionnaire that assesses activity and social limitations caused by musculoskeletal injury. After completing the questionnaires, subjects will be fit with the Stepwatch Activity Monitor (SAM, Cyma, Seattle WA) around their ankle. An investigator will give them verbal instructions about wearing the SAM. This is a small, pager-sized device which counts the number of steps taken by the wearer. The SAM will be worn around the subject's ankle for 14 days, and then the subject will return the monitor and activity log to the VA by visit or by mail. Assessments using the MFA and SF-36 will occur prior to surgical intervention and at 3, 6, 12, 24, and 36 months following the intervention. Long term follow-up using the MFA and SF-36 was approved in April 2017 and will continue until 12 years after the participant's ankle surgery. Assessments using the SAM will occur prior to surgical intervention and at 3, 6, 12, 24 and 36 months following the intervention. These assessments will provide data on functional limitations due to ankle arthritis and on the efficacy of the treatments in restoring functional ambulation.

Biomechanical domain: Instrumented gait analysis will be performed on each subject. Reflective markers will be placed on each subject's head, hands, arms, trunk, legs, and feet. The subject will walk along a 12 m walkway with embedded forceplates. The motion of the markers will be collected with a 10 camera Vicon 612 system and processed to determine the motion of the ankle joint in three planes as well as the moment and power generated by the ankle during walking. This will allow us to assess the technical functional of the ankle joint, the range of motion used during gait and the moment, power and energy contribution of the ankle during walking for each of the treatments. Gait assessments will occur prior to surgical intervention and at 12, 24, and 36 months post-op. Gait assessment takes place at the VA Puget Sound Health Care System in Seattle, WA. The investigators will only recruit subjects from the VA and Harborview Medical Center for the gait analysis portion of the study.