In brief:

• Researchers analyzed Knee Injury and Osteoarthritis Scores (KOOS) of 118 young adults who experienced an ACL tear, comparing baseline with 5-year KOOS
• Some participants received early ACL reconstruction surgery followed by exercise therapy; others received delayed surgery with a period of exercise therapy prior to the surgery; a third group received exercise therapy only
• Researchers matched baseline and 5-year KOOS with "prognostic factors" associated with worse outcomes—cartilage and meniscus damage, osteochondral lesions, and knee extension deficits
• Overall findings: early surgery was more often associated with worse outcomes, compared with delayed surgery or no surgery
• In the early-surgery group, participants with meniscus damage at baseline reported worse KOOS at 5 years than did participants without meniscus damage at baseline; the delayed surgery group reported the opposite, with the meniscus-damage subgroup reporting KOOS gains over those without meniscus damage

Researchers analyzing a study of patients with anterior cruciate ligament (ACL) tears have begun to connect the dots between early indicators of long-term outcomes and the kinds of treatments patients receive. They reached the conclusion that, for at least some, putting off ACL reconstruction surgery in favor of exercise therapy could be the way to go.

In what authors call a "post-hoc exploratory, hypothesis-generating analysis of outcomes," researchers used data from the Knee Anterior Cruciate Ligament Nonsurgical versus Surgical Treatment (KANON) clinical trial conducted in Sweden to analyze how Knee Injury and Osteoarthritis Outcome Scores (KOOS) 5 years after injury compared with the presence of various baseline "prognostic factors" known to correlate to worse long-term outcomes. The trial focused on relatively active young adults (18-35 years) with no prior knee injuries who suffered an acute ACL rupture and began treatment within 4 weeks after injury.

The researchers knew that the 4 prognostic factors—baseline cartilage and meniscus damage, osteochondral lesions, and knee extension deficits—increased the chances of worse outcomes at 5 years. What they wanted to find out was whether early ACL reconstruction surgery actually made those chances worse, compared with surgery delayed in favor of exercise therapy, or exercise therapy alone was responsible. Results were published in the British Journal of Sports Medicine (BJSM).

A total of 118 participants were studied, with 59 receiving early (within 4-6 weeks) ACL surgery followed by exercise therapy, 30 receiving exercise therapy followed by surgery 2 to 56 months later, and 29 receiving exercise therapy only. All patients participated in the same "goal-oriented, physiotherapist supervised neuromuscular program at 9 outpatient clinics," according to authors. Functional measures were collected at baseline, 3 months, 6 months, 12 months, 24 months, and 5 years, with results adjusted for sex, age, body mass index, preinjury activity, education, and smoking.

Among the findings:

• For participants with baseline meniscus damage, early surgery followed by exercise therapy resulted in a KOOS that averaged 14 points worse than scores reported by participants with no baseline meniscus damage. But in what authors call a "surprising" result, when participants with baseline meniscus damage participated in exercise therapy and delayed surgery, their KOOS wound up being, on average, 14 points higher than those with no baseline meniscal injury.
• Similar, albeit lower, effects were recorded for patients with baseline osteochondral lesions (average 5.4 points worse for the early-surgery group; average 6.2 points better for the delayed-surgery group in KOOS for pain). Participants in both categories (early vs delayed exercise) who reported baseline knee extension deficits reported small decreases for most KOOS categories.
• Overall, participants whose ACL injury was managed with exercise therapy alone reported an estimated 10-point better KOOS at 5 years compared with the early surgery group.
• Participants who received exercise therapy alone but later received " non-ACL surgery"—a knee surgery that was not ACL reconstructive—reported an estimated 14-point worse KOOS at 5 years compared with participants who received exercise therapy alone and no other surgeries.

Authors of the study acknowledge that the findings related to meniscus damage were particularly unexpected, but not exactly beyond reason.

"The mechanisms behind this surprising finding are not clear, but sustaining a second knee insult in the form of an early ACL reconstruction shortly after a previous knee trauma may increase the likelihood of experiencing persistent postoperative difficulties," authors write. They also speculate that the delayed-surgery group may have experienced more pain than their counterparts without meniscus injuries, and, as a result, "reconstructive surgery may have been more successful in relieving pain … compared with those electing to undergo surgery for a range of other reasons, including a desire to gain preinjury status, a pre-existing preference for surgery, and finding exercise therapy boring and time-consuming."

Researchers also found that the baseline KOOS scores themselves functioned as prognostic factors for worse 5-year outcomes, with early-surgery participants who reported lower KOOS at baseline in turn reporting lower KOOS at 5-year follow-up compared with their delayed-surgery counterparts who also reported lower-baseline KOOS.

"Low baseline KOOS scores also reflect more physical impairment and this may predispose an individual to worse postoperative outcomes," authors write. "Individuals who report worse KOOS scores prior to reconstruction may benefit from postponing surgery and commencing exercise therapy before considering surgical reconstruction."

Authors acknowledge that the "exploratory nature" of their research included several limitations, including low sample size, lack of adjustment for multiple comparisons, and confidence intervals "suggesting uncertainty in some of the estimates." Still, they argue, this initial work is worth further exploration and, at the very least, could help to reinforce the concept that clinicians must approach treatment of ACL injuries at the individual patient level.

Research-related stories featured in PT in Motion News are intended to highlight a topic of interest only and do not constitute an endorsement by APTA.