ANN ARBOR, Michigan–Nearly 7% of anterior cruciate ligament (ACL) injuries in young athletes lead to an early onset of osteoarthritis (OA). A new study at the University of Michigan will try to determine the earliest signs of degenerative arthritis in young knees, in the hope of developing early intervention that would prevent the progression to OA.
Lead investigator Riann Palmieri-Smith, PhD, ATC, assistant professor, Division of Kinesiology at the University of Michigan and director of the Athletic Training Education Program, discussed the study with CIAOMed. The research, which is funded by the National Football League Charities Foundation, is set to begin accrual and should be complete in 18 to 24 months, she said. Edward Wojtys, MD, medical director of MedSport Sports Medicine Program at the University of Michigan is co-investigator on the study.
This prospective study will enroll a relatively homogenous group of 20 athletes who have sustained an acute ACL rupture and are scheduled for reconstructive surgery, 20 matched teammate controls with normal knees, and 20 matched acquaintance controls with normal knees. At baseline and again 12 months after surgery, the investigators will measure serum concentrations of biologic markers of inflammation (high-sensitivity C-reactive protein, RP) and cartilage matrix turnover (cartilage oligomeric matrix protein, COMP). They will also examine magnetic resonance images (MRIs) to assess changes in cartilage morphology and changes in extracellular matrix components.
The teammate controls are being studied because some data have suggested that participating in sports with high joint loads and repeated microtraumas to body tissues might increase the risk of subsequent OA.
"Choosing a noninjured teammate participating in the same sport will allow us to consider whether elevated biomarker concentrations are present in athletes in general regardless of injury status, which may suggest that athletes, prior to sustaining a major injury, may be predisposed to later developing arthritis. This control will be age, gender, and ethnicity matched to the injured athlete and is more likely to control for the environment surrounding the injury, such as controlling for the types of surfaces played upon. The control will also represent a similar mechanical environment in which "high loads" are regularly transmitted to the knee joint," Dr. Palmieri-Smith said. "These data will be used to test our hypotheses that biomarkers of articular cartilage degradation are elevated in those with subchondral bone lesions and that bone bruises result in cartilage injury and loss of matrix integrity, as detected by MRI."
The primary study end points are T2 relaxation times for the area overlying the bone bruise and the relaxation times on the opposite side of the joint from the bone bruise (medial side).
The investigators hope to lay the groundwork for later studies of possible interventions to prevent knee injuries from developing into knee OA, but Dr. Palmieri-Smith emphasizes that this will require considerably more basic research into the underlying pathogenic mechanisms. "There is not enough evidence elucidating the cause of post-traumatic OA associated with ACL injury, so it would be difficulty to implement an effective intervention at this point in time. After we complete this study we hope to have a better understanding of post-traumatic OA and plan to study interventions as a next step," she said.
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Reference:
1. Common childhood sports injury can lead to early onset of arthritis [press release]. Ann Arbor, Michigan: University of Michigan: August 7, 2006