Study was terminated due to lack of funding and unforeseen delays.

Patients who have had a total ankle joint replacement surgery typically have limited movement in their ankles possibly due to the fact that commonly used ankle joint prosthetic devices only allow limited axes of motion.

This study will evaluate the ability of a Scandinavian Total Ankle Replacement (STAR) mobile-bearing prosthesis and INBONE 2 fixed-bearing prosthesis to restore triplanar motion in the tibiotalar (ankle) joint following a surgical arthroplasty (total joint replacement) procedure.

3D X-ray video motion analysis will be utilized to quantify range of motion measurements in two groups of ankle prosthesis users and a group of matched control participants.

15 study participants will include those using a Stryker STAR prosthesis and a Wright Medical INBONE 2 prosthesis and a group of matched control subjects.

CT scans of lower limb anatomy (ankle-foot complex) will be obtained for all subjects to be converted into 3D bone surface models for use in the joint motion tracking software.

Each participant will participate in one day of data collection with an X-Ray Motion Analysis (XMA) system. High-speed biplanar XMA system will capture video images of the skeletal motions within the foot-ankle complex during normal movement. Subjects will walk and perform controlled movements in the capture volume within the XMA system.

Following data collection, the 3D bone surface models will be mapped to the sagittal (side view), coronal (front view), and axial (top view) plane skeletal motions demonstrated in the collected x-ray videos. Motion tracking data will then be used to accurately animate the 3D bone models to demonstrate the active range of ankle-foot joint motions during voluntary movement and gait.

Resulting range of motion measurements in dorsiflexion/plantarflexion, internal/external rotation, and inversion/eversion will be used to determine the extent to which normal motion in the ankle-foot complex has been restored in ankle prosthesis users.

INCLUSION CRITERIA:

• Between 18 to 79 years of age.

Additional Inclusion criteria for mobile-bearing ankle prosthesis user group:

• Able to walk independently with their prosthesis at different self-selected speeds
• Implanted with Stryker Scandinavian Total Ankle Replacement (STAR) prosthesis at least one year prior to enrollment
• Pain free and radiologically normal
• Able to walk at preferred walking speed without an assistive device (e.g., cane, crutches, etc.)

Additional Inclusion criteria for control group:

• Within 3 years of age of one of the mobile-bearing ankle prosthesis user participants
• Same gender as the matched mobile-bearing ankle prosthesis user participant
• Not have a history of major musculoskeletal injuries
• Not have a history of major neuromuscular injuries

Additional Inclusion criteria for fixed-bearing ankle prosthesis users:

• Able to walk independently with their prosthesis at different self-selected speeds
• Implanted with INBONE 2 prosthesis at least one year prior to enrollment
• Pain free and radiologically normal
• Able to walk at preferred walking speed without an assistive device (cane, crutches, etc.)

EXCLUSION CRITERIA:

• Have dementia or an inability to give informed consent
• Have significant or chronic loss of hip or knee joint motion
• Have any subtalar or hindfoot fusion
• Have a history of dizziness and/or balance problems
• Have had any additional x-ray exposures in the past year that would put beyond the recommended annual dose for the study
• Are pregnant
• Exhibit evidence of polysubsidence (implant loosening)
• Exhibit evidence of a broken implant

Study participants meeting the eligibility criteria will be convenience-sampled from within the metro-Atlanta area. Eligible participants with either a STAR or INBONE 2 prosthesis will be identified from among clinical populations treated at the Emory University Hospital. Control group participants will be convenience-sampled from within the metro-Atlanta area.

Control group participants were not enrolled due to early termination of the study.

Adverse event data were collected only during the period of study participation (typically less than 1 week).

An early termination of the study led to a smaller number of subjects enrolled/analyzed than originally planned.