How to prevent secondary posttraumatic knee osteoarthritis

LAS VEGAS – 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.