LAS VEGAS (FRONTLINE MEDICAL NEWS) – A variety of evidence-based strategies are available for preventing posttraumatic knee osteoarthritis (KOA) in patients who have already sustained an anterior cruciate ligament (ACL) injury. And they’re generally ignored, according to May Arna Risberg, PhD.

“We have a lot of knowledge. We can use secondary prevention strategies. And here I think we, as physical therapists, physicians, and orthopedic surgeons, are doing a lousy job because we are sending these ACL-injured patients back to sports before they have normalized knee function and quadriceps strength,” said Dr. Risberg , professor of sports medicine at the Norwegian School of Sport Sciences in Oslo.

With no proven disease-modifying therapy for KOA available to date, secondary prevention of posttraumatic KOA is worthy of high-priority status, she said at the World Congress on Osteoarthritis. An estimated 250,00 ACL injuries occur annually in the United States, and up to one-half of affected patients, most of whom are young, active people, will experience a second ACL rupture within the first few years after undergoing their initial reconstruction. This second ACL injury greatly increases their risk of developing posttraumatic KOA within 15-20 years, while they are still relatively young, she said.

Moreover, if the second ACL injury involves meniscus surgery, the 5-year risk of posttraumatic KOA roughly triples to up to 48%.

She highlighted a few effective strategies for preventing posttraumatic KOA in patients who already have an ACL injury.

Avoid reinjury

Dr. Risberg was senior author of a recent report from the prospective Delaware-Oslo Cohort Study involving 106 athletes who underwent ACL reconstruction following injury in what she termed level I sports. These are sports that entail lots of pivoting, jumping, and hard cutting, such as basketball, soccer, and handball.

In the first 2 years after ACL repair, 30% of patients who returned to participation in a level 1 sport experienced an ACL reinjury, compared with just 8% who opted for a lower-level sport. Athletes who returned to a level 1 sport had an adjusted 4.3 times greater ACL reinjury rate than those who didn’t, Dr. Risberg noted at the congress sponsored by the Osteoarthritis Research Society International.

The good news is that this sharply increased reinjury risk was mitigated if return to a level 1 sport was delayed for at least 9 months post surgery and if the patient had regained quadriceps strength comparable to the uninjured side. For every month that return to sport was delayed out until 9 months post ACL reconstruction, the knee reinjury rate was reduced by 51% ( Br J Sports Med. 2016;50:804-8 ).

In a meta-analysis by other investigators of 12 studies including 5,707 participants, weakness of the knee extensor muscles was independently associated with a 1.65 times increased risk of developing KOA ( Osteoarthritis Cartilage. 2015 Feb;23[2]:171-7 ).

Attend to BMI

A discussion of the importance of maintaining a healthy body weight is an important aspect of patient education for athletes with knee injuries. In a cohort study of 988 patients who underwent primary ACL reconstruction, being overweight or obese was associated with a significantly increased risk of subsequent meniscal tears and chondral lesions ( Am J Sports Med. 2015 Dec;43[12]:2966-73 ).

Also, it’s well established that obesity is a risk factor for knee OA, and Canadian investigators have shown that young athletes with a sports-related intra-articular knee injury were 3.75 times more likely to be overweight or obese 3-10 years post injury, compared with matched uninjured controls ( Osteoarthritis Cartilage. 2015 Jul;23[7]:1122-9 ).

Consider prehabilitative exercise training

Dr. Risberg and coinvestigators have reported that preoperative quadriceps muscle strength deficits are predictive of impaired knee function, as measured by the Cincinnati Knee Score 2 years post surgery. She said she believes ACL reconstruction shouldn’t be done until quadriceps muscle strength is at least 80% of that in the uninjured limb ( Br J Sports Med. 2009 May;43[5]:371-6 ). She and her coinvestigators have published the details of a 5-week progressive exercise therapy program in which they have shown results in significantly improved early postoperative knee function ( J Orthop Sports Phys Ther. 2010 Nov;40[11]:705-21 ). They now try to have patients complete the twice-weekly, 5-week program before final decisions are reached regarding whether to have ACL reconstruction.

Test all before okaying return to sport

It’s important to know if patients who have undergone ACL reconstruction have gotten full knee function back before determining if they’re ready for full-on sports participation. In the Delaware-Oslo Cohort Study, patients who delayed their return until at least 9 months after surgery and passed the return-to-sports test had a 5.6% reinjury rate within 2 years, while those who failed the return-to-sports criteria had a 38.2% ACL reinjury rate.

The return-to-sports testing utilized in this study entailed isokinetic quadriceps strength testing, the single hop leg test, the 14-item self-rated Knee Outcome Survey–Activities of Daily Living Scale, and a self-rated Global Rating Scale of perceived function on a 0-100 scale. To be cleared for return to sports, a patient had to demonstrate having regained at least 90% of quadriceps muscle strength and hop performance along with scoring in the normative range on both of the self-rating instruments.

Surgical vs. nonsurgical treatment of ACL rupture

The evidence on this score is conflicting, according to Dr. Risberg. While most physical therapists believe ACL reconstruction doesn’t protect against later development of KOA, as reflected in a meta-analysis of published studies ( J Bone Joint Surg Am. 2014 Feb 19;96[4]:292-300 ), a more recent retrospective comparison of 964 patients with an isolated ACL tear and an equal number of matched controls concluded that patients treated nonoperatively were six times more likely to have been diagnosed with KOA and 16.7 times more likely to have undergone total knee replacement at a mean follow-up of 13.7 years than were those treated with ACL reconstruction ( Am J Sports Med. 2016 Jul;44[7]:1699-707 ).

Dr. Risberg’s fellow panelist Jackie Whittaker, PhD , said that, as long as quadriceps muscle strengthening is a priority, it makes sense to strengthen the hamstring as well, particularly if the ACL reconstruction utilized the hamstring tendon.

“Also, I would add that it’s important to develop a relationship with these ACL-injured people, who are often very young. Preventing a disease that they’re going to get 20 years later isn’t a priority for them. You need to develop that relationship and build it up over time. Helping them set realistic expectations is very important. And we need to do what we can to help them find some sort of competitive outlet. A lot of these kids were very competitive, and now they’ve had an injury and can’t compete. They don’t want to go back to playing just any sport. They want to be able to be competitive, and if you don’t help them find another way to express that, they sort of give up on physical activity altogether,” according to Dr. Whittaker of the University of Alberta in Edmonton.

Dr. Risberg and Dr. Whittaker reported having no financial conflicts of interest.