The study will prospectively enroll and follow 300 participants ages 18-60 surgically treated for a lower-extremity articular injury including fractures of the tibial plateau, pilon, ankle, and calcaneus.

The study will prospectively enroll and follow 300 participants ages 18-60 surgically treated for a lower-extremity articular injury including fractures of the tibial plateau, pilon, ankle, and calcaneus. All participating centers will undergo training to implement the Mobility Toolkit (MTK). Research Staff will facilitate a series of performance tests while participants wear the MTK device. MTK assessment will also be conducted on 150 non-injured adults matched to the injured cohort on age and gender. These individuals will be enrolled and assessed once at two participating centers. Study flow and data capture are summarized in the figure on the next page.

Inclusion Criteria:

1. 18-60 years of age
2. Open or closed fractures of the tibial plateau, pilon, ankle or calcaneus requiring surgical fixation.

Exclusion Criteria:

1. Gustilo type IIIB or IIIC injuries
2. No other surgically or non-surgically treated injuries that impact gait (e.g. upper extremity injury proximal to the elbow; spinal cord injury; contralateral or ipsilateral fractures).
3. Neurologic impairment or deficit that impairs gait
4. Prior injuries or conditions that alter gait (e.g. severe osteoarthritis)
5. Severe problems with maintaining follow-up (e.g. participants who are prisoners, who are intellectually challenged without adequate family support, or have documented psychiatric disorders).
6. Unable to provide informed consent in English or Spanish.

Adults ages 18-60 surgically treated for a fracture of the tibial plateau, pilon, ankle, or calcaneus at one of 10 participating centers. Patients meeting the inclusion and exclusion criteria will approached for enrollment in to the study.

Data sharing beyond manuscripts and scientific presentations will be processed through the METRC website in the short term. Currently, a standard form will be available for researchers outside METRC to request access to final data generated from METRC studies. These requests will be transmitted to the METRC Coordinating Center for initial review to make sure the relevant materials are provided in support of the request. METRC is committed to making data as widely available as possible while safeguarding the privacy of study participants and protecting the intellectual property of the Consortium.

Data will only be made available after it is completely stripped of identifiable information such as dates, geographic locators, and any other event information which is sufficiently rare as to make it possible to deduce the identity of an individual participant. When necessary for complete de-identification, data may be grouped.