Benched to Bedside: Treatment of ACL Tears

Published - Written by Rena Xu

For athletes and otherwise physically active young adults, a rupture of the anterior cruciate ligament (ACL) represents a potentially devastating injury. The injury may leave the knee unstable and poorly functional, increase the risk of damage to the knee’s articular cartilage and menisci, and seriously diminish the capacity to engage in high-demand physical activity. Many affected athletes have no choice but to give up competitive sports for extended periods of time.

Early surgical reconstruction is currently the preferred option for treating ACL tears, especially among patients eager to return to competitive sports. As a result, the number of ACL reconstructions performed each year is high, even though there has been a lack of high-quality evidence from randomized, controlled trials to support the notion that surgery is necessary for achieving good outcomes. Estimated direct costs associated with ACL reconstructions in the US are $3 billion annually.

This week, Frobell et al. report the results of a randomized, controlled trial conducted in Lund, Sweden, among 121 non-elite athletic adults 18 to 35 years of age with acute ACL tears. The trial investigated whether a strategy of early reconstructive surgery with rehabilitation did in fact yield outcomes superior to an alternative strategy of structured rehabilitation with optional delayed surgery if symptomatic knee instability persisted. Rehabilitation consisted of phased exercises with goals defined for range of motion, muscle function, and functional performance.

The trial results suggested that there was no significant difference in outcomes between those randomized to early reconstruction as compared with those randomized to initial rehabilitation with the option for delayed reconstruction. The primary outcome measured was the change between baseline and two years in the average score for four subscales of the Knee Injury and Osteoarthritis Outcome Score (KOOS): pain, symptoms, function in sports and recreation, and knee-related quality of life. Both groups showed substantial improvement.

These results may carry implications for the clinical management of ACL injuries. Frobell et al. report that in their trial, surgery was avoided in 61% of subjects without compromising two-year outcomes. This would seem to suggest that a strategy of starting with rehabilitation instead of reconstruction could yield the same results with fewer patients having to undergo immediate reconstructive surgery.

At the same time, there may be differences between the treatment groups not captured by the primary outcomes measured in this trial. Dr. Bruce Levy of the Mayo Clinic suggested in an accompanying editorial that the KOOS measure of knee symptoms and function, although useful and well-validated, “does not reflect the long-term function of the knee or the risk of recurrent episodes of instability.” He further noted, “The group assigned to optional delayed reconstruction underwent significantly more meniscal procedures during follow-up than did the group assigned to early reconstruction. Although this finding might be explained by the greater likelihood of concomitant meniscal surgery among patients undergoing early ACL reconstruction, a concern is that unstable knees may have been more prone to meniscal damage during the follow-up period.”

One might also find it concerning that of the patients in the study group initially treated with rehabilitation without surgery, nearly 40% later underwent delayed ACL reconstruction due to continued knee instability. Although these patients had similar outcomes to their counterparts who received early reconstruction, it is possible that some experienced a prolonged period prior to surgery with unresolved impairment and diminished capacity for physical activity. For competitive athletes looking to regain the ability to participate in high-demand sports, this represents a considerable loss of time and opportunity.

Dr. Jeffrey Drazen, editor-in-chief of NEJM, said, “We published this article to be sure that the discussion about how to deal with this complex injury was based on evidence rather than anecdotal experience.”

Understanding the full range of implications for different treatment strategies will require more work. Nevertheless, the results of this trial raise interesting questions about how systems-wide versus individual demands should influence practice guidelines. As a physician, would you be comfortable starting treatment of most ACL injuries with rehabilitation instead of defaulting to surgery? As an injured athlete, would you be willing to start on a “rehabilitation only” treatment strategy, knowing that it might not work and leave you in need of surgery anyway down the road? And as a health care manager, would you change your institution’s model of coverage or reimbursement for ACL reconstruction, with the goal of avoiding a significant percentage of surgeries while still realizing similar clinical benefits?

For a supplementary view of how to clinically evaluate knee injuries, see this week’s Video in Clinical Medicine by Dr. Teresa Schraeder et al.