New Treatment Improves Knee Recovery in Athletes

A new drug target could help prevent muscle weakness and atrophy following anterior cruciate ligament (ACL) knee injury among athletes.

Researchers at the University of Michigan Health System (Ann Arbor, MI, USA) conducted a study involving 18 patients (mean age 28 years) who underwent surgical reconstruction of the ACL after a noncontact athletic injury. The researcher subsequently measured circulating levels of proatrophy, proinflammatory, and cartilage turnover cytokines and biomarkers that would increase after ACL reconstruction. The measurements were accompanied by objective knee-strength measures preoperatively and at six postoperative visits.

The results showed that myostatin, TGF-β, and C-reactive protein (CRP) levels were significantly increased in the early postoperative period and returned to baseline. Cartilage oligomeric matrix protein levels decreased immediately after surgery and then returned to baseline. CCL2, CCL3, CCL4, CCL5, EGF, FGF-2, IGF-1, IL-10, IL-1α, IL-1β, IL-1ra, IL-6, myoglobin, and TNF-α were not different over the course of the study. The researchers concluded that the therapeutic inhibition of myostatin might help prevent the muscle atrophy that occurs after ACL reconstruction. The study was published in the June 2013 issue of the American Journal of Sports Medicine.

“A hormone called myostatin that blocks muscle growth appears to play a key role in causing muscle damage after ACL tears,” concluded lead author Christopher Mendias, PhD, ATC, assistant professor of orthopedic surgery and molecular & integrative physiology. “This is the first study in humans to open the door to a potential therapy to prevent muscle atrophy. We see this as an important step in restoring athletic and functional abilities in the short term, and in preventing osteoarthritis in the long term.”

After ACL reconstruction, there is significant atrophy of the quadriceps muscles that can limit full recovery and place athletes at risk for recurrent injuries with return to play. The findings pave the way for potential treatment preventing muscle loss after an ACL tear and consequent knee replacement, which affects more than 250,000 people a year in the United States alone.

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