LIVERPOOL, ENGLAND – Decades after they were sustained, acute knee injuries caused clinically significant impairments in patient-reported outcomes, as well as upped the risk for knee osteoarthritis (OA) in an observational study.

Results of the study, which followed up individuals 32-37 years after they were treated for a ruptured anterior cruciate ligament (ACL) injury between 1980 and 1985, showed that, compared with the general population, they experienced greater levels of knee pain, participated less in physical activities, and had a reduced quality of life.

Furthermore, of 136 patients who underwent X-rays that were graded by an experienced radiologist, 6% had knee replacements and about 70% had developed knee OA.

The link between OA and ACL injury is not new, with prior estimates suggesting that up to half of all patients with ACL injury develop OA within 10 years of the injury, said Stephanie Filbay, PhD, who presented the results of the study at the World Congress on Osteoarthritis. There have also been reports of knee pain and other symptoms, and poor quality of life more than 5 years later. What’s not been known until now, however, is what happens with even longer term follow-up, said Dr. Filbay, a postdoctoral research fellow in sport, exercise, and osteoarthritis at the University of Oxford, England.

The aims of the study were to compare patient-reported outcomes at 32-37-years’ follow-up against the general population, then to see if the baseline injury or treatment approach, or knee function 3-7 years after the initial injury had any influence on outcomes.

The study included 223 patients who were between aged 15 and 40 years at the time of the acute ACL injury between 1980 and 1985 and who had been seen within 2 weeks of ACL rupture at Linköping University Hospital in Linköping, Sweden. Patients had been allocated to early surgical or non-surgical treatment based on having an odd or even birth year. They had then been assessed 3-7 years later using a variety of tests to determine the strength of their quadriceps and hamstrings and the ability to hop on one leg.

All patients were then invited 32-37 years later after the initial injury to complete questionnaires and undergo clinical examination and X-rays. Only four people declined and 38 did not answer, leaving 181 (81%) people who agreed to participate and complete the Knee injury and Osteoarthritis Outcome Score (KOOS) and the ACL quality of life questionnaire (ACL-QOL).

The average age of participants at follow-up was 59 years (range, 47-74 years); 30% were female. 58% of all patients had been treated non-surgically initially, and 38% remained non-surgically treated at the longterm follow-up. At baseline, 58% had a meniscus injury.

Compared with an age- and sex-matched Swedish population, patients with ACL injuries had a lower KOOS for pain, sport/recreational activities, and quality of life. For example, KOOS for knee pain was around 65-70 for those with prior ACL injuries, compared with 80-90 for those without ACL injuries, where 100 indicates the best outcome or least pain and zero the worst.

KOOS was not affected by whether or not patients had initial ACL surgery or surgery at any point in their follow up. It also did not appear to matter if patients had a meniscal injury at baseline or not.

Quadriceps and hamstring strength at the 3-7 year postinjury assessment did not affect the longterm KOOS, but the ability to hop on one leg did: Those who were not able to hop on one leg for more than 90% of the time on the unaffected limb at the 3-7 years follow-up had worse pain, symptoms, function, and quality of life at the longterm follow-up point.

With regards to OA, “overall, more than one in two individuals had Kellgren-Lawrence grade 4 that could be considered severe radiographic changes in at least one compartment,” Dr. Filbay said at the meeting, which is sponsored by the Osteoarthritis Research Society International.

Severe radiographic changes were most common in the tibiofemoral joint, with around 47% having Kellgren-Lawrence (KL) grade 4. About 35% of tibiofemoral joints and about 60% of patellofemoral joints were KL grade 1.

Interestingly, different factors were found to be associated with OA in the tibiofemoral and patellofemoral joints, according to Dr. Filbay. Patients who had been treated non-surgically, whether initially or at any time during the 32-37 year follow-up, were more likely to have tibiofemoral OA, whereas those who had been treated surgically tended to have patellofemoral OA.

“Perhaps not surprisingly, meniscal injury at baseline was related to a higher percentage of tibiofemoral OA at long-term follow-up,” Dr. Filbay said.

Another finding was that patients with weaker hamstrings 3-7 years after the injury were more likely to develop patellofemoral joint OA.

Dr. Filbay had no disclosures.

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SOURCE: Filbay S, et al. Osteoarthritis Cartilage 2018:26(1):S52-3. Abstract 80.

Patient-reported outcomes show impairment decades after acute knee injury