La Trobe researchers say crepitus signals more pain and poorer function in the short term but does not predict worsening joint damage over five years.
Knee crepitus in young adults following anterior cruciate ligament reconstruction is not a reliable predictor of early-onset osteoarthritis, according to new findings from La Trobe University.
The researchers said the study supported a more nuanced approach to diagnosing early-stage osteoarthritis and encouraged health professionals to avoid overinterpreting crepitus in young, active patients.
Their prospective study, published in Arthritis Care & Research, followed 112 participants (median age 28, 41 female) who were tracked with MRIs and patient-reported outcomes for five years following anterior cruciate ligament reconstruction surgery (ACLR).
Crepitus was associated with full-thickness cartilage defects and worse symptoms at one year (2.7 times greater prevalence of full-thickness patellofemoral cartilage lesions); and more pain, poorer knee-related quality of life and reduced function compared to those without crepitus, scoring on average 6-10 points lower on validated outcome measures.
However, longitudinal MRI assessment showed no increased risk of worsening structural features, including cartilage lesions, osteophytes or bone marrow lesions, between years one and five.
Patient-reported pain and function also improved over time in the crepitus group, narrowing the early gap.
La Trobe graduate researcher and physiotherapist Jamon Couch said that knee crepitus – the sound of cracking or grinding in the knee joint – was common among all age groups after ACLR.
“We found that those with knee crepitus demonstrated more than two and a half times greater rates of full-thickness cartilage defects in the kneecap area, with more pain and poorer function early on,” he said.
“But over the next four years, those with crepitus did not experience worse pain and function compared to those without knee crepitus.”
Research has shown about 50% of people with an ACL rupture developed osteoarthritis symptoms and structural changes within a decade of injury, nearly 15 years earlier than the uninjured.
However, these findings challenge the idea that crepitus should be used to diagnose or predict early osteoarthritis following traumatic knee injury in young adults.
Dr Adam Culvenor, head of the Knee Injury Research Group at La Trobe’s Sport and Exercise Medicine Research Centre (LASEM), said the research was reassuring for younger patients worried that noisy knees were a red flag signalling their joint was deteriorating after surgery.
“It also highlights the importance of staying active and engaged in rehabilitation to avoid or delay osteoarthritis,” Dr Culvenor said.
Related
Self-reported crepitus was associated with full-thickness patellofemoral cartilage lesions one year post-ACLR (prevalence ratio 2.70, 95%CI 1.41, 6.39) but not the risk of worsening structural osteoarthritis features between one and five years post-ACLR. Those with crepitus reported worse pain (β -6.42, 95%CI -10.47, -2.36), QoL (β -10.39, 95%CI -18.58, -2.20) and function (β -5.49, 95%CI -10.92, -0.06) one year post-ACLR, but greater improvement in pain and function between one and five years.
As part of the study, participants self-reported the presence/absence of knee crepitus using an item from the Knee Injury and Osteoarthritis Outcome Score (KOOS).
Patellofemoral and tibiofemoral osteoarthritis features (i.e. cartilage lesions, osteophytes, bone marrow lesions) were assessed from MRIs at one and five years post-ACLR. Self-reported outcomes were assessed with two KOOS subscales (pain, quality of life [QoL]) and the International Knee Documentation Committee subjective evaluation form (i.e. self-reported function).
Poisson regression evaluated the relationship between self-reported crepitus and the presence/worsening of structural osteoarthritis features, while general linear models explored the relationship between crepitus and self-reported outcomes.
“Self-reported knee crepitus was associated with the presence of full-thickness patellofemoral cartilage defects 1-year post-ACLR, but was not associated with a greater risk of worsening structural osteoarthritis features up to five-years post-ACLR,” the authors concluded.
“One-year post-ACLR, those with crepitus reported worse pain, knee-related QoL and function.”
