Preventing Posttraumatic Osteoarthritis With Physical Activity Promotion

Osteoarthritis (OA) is a leading cause of disability worldwide that affects millions of Americans each year. Posttraumatic OA (PTOA) significantly impacts patients after anterior cruciate ligament (ACL) injury and ACL reconstruction (ACLR) with approximately 50% of patients developing PTOA within 20 years of injury or surgery. Knee joint mechanical loading measured via physical activity (i.e. daily steps) is insufficient in individuals after ACLR compared to uninjured individuals. Establishing the beneficial effects of physical activity to promote optimal free-living knee joint mechanical loading and improve knee joint health will aid in the development of cost-effective interventions that prevent PTOA and health burden of the disease.

Osteoarthritis (OA) is a leading cause of disability worldwide resulting in severe limitations in daily activities and chronic pain. It is estimated that 35% of posttraumatic OA (PTOA) cases occur after knee injuries and surgeries such as anterior cruciate ligament (ACL) injury and ACL reconstruction (ACLR). Optimal free-living mechanical loading, which refers to the forces acting on the knee caused by daily activities, plays an essential role in maintaining knee articular cartilage health. After ACLR, individuals take fewer steps per day as compared to uninjured controls. This results in insufficient free-living mechanical loading to joint tissues and is associated with early PTOA development. Adequate physical activity (PA) is recommended to help reduce risk of PTOA, but it is unclear how changes in PA acutely impact knee joint cartilage health. The overall objective of this pretest-posttest experimental pilot study is to determine how optimizing free-living mechanical loading through PA promotion improves cartilage composition in individuals who demonstrate insufficient free-living mechanical loading after ACLR. PA promotion will be delivered over 8 weeks using commercially available PA monitors and the patients' smartphone to provide daily personalized and achievable step goals to increase daily step counts to a level consistent with healthy PA participation. The hypothesis for aim 1 is that MRI markers of proteoglycan density associated with PTOA development will improve after 8-weeks of PA promotion exposure. Hypothesis for aim 2 is that greater changes in steps per day will be associated with improved proteoglycan density. Change in MRI markers of proteoglycan density and steps per day will be assessed using a pretest-posttest design in 8 adults who are 6 months to 5 years post-ACLR with insufficient mechanical loading (\<8,000 steps per day)24 and suboptimal quality of life (quality of life survey\<87.5). Outcomes will be collected before (pretest) and after (posttest) 8-weeks of PA promotion. For the PA promotion, participants will receive a text message each morning with a personalized, daily step count goal and a link used to confirm receipt of the goal. The preceding 10 days of step data will be rank ordered and the 60th percentile step count will be set as the goal for the next day. The proposed work is innovative, in that this study will use a novel combination of outcomes that will lead to unprecedented insight into the influence of PA promotion in mitigating early PTOA development.

Eligibility Criteria:
Inclusion Criteria

Participants will be included if they:

* Provide informed consent and sign a HIPPA form prior to any study procedures are performed
* Have completed all other formal physical therapy and therapeutic exercise regimens, and will not be engaging in any other formal therapy for their ACLR during the study
* Are between the ages of 18 and 35.
* Underwent an ACLR no earlier than 6 months and no later than 5 years prior to enrollment.
* Demonstrate \< 8,000 steps per day during the screening phase of the study as assessed using the Actigraph GT9X Link monitor.
* Demonstrate clinically relevant-knee symptoms, defined as a Knee Injury and Osteoarthritis Outcomes Score (KOOS) quality of life subscale \< 72.2

Exclusion Criteria

Participants will be excluded if:

* The participant underwent an ACLR revision surgery due to a previous ACL graft injury.
* Multiple ligament surgery was indicated at the time of ACLR surgery.
* A lower extremity fracture was suffered during the ACL injury.
* The participant has been diagnosed with osteoarthritis in either knee
* They have a cochlear implant, metal in body, claustrophobia, or history of seizures.