Early knee osteoarthritis is evident one year following anterior cruciate ligament reconstruction: A magnetic resonance imaging evaluation
Culvenor AG, Collins NJ, Guermazi A, Cook JL, Vicenzino B, Khan KM, Beck N, van Leeuwen J, & Crossley KM. Arthritis & Rheumatology. Online ahead of print, December 16, 2014.
Take Home Message: There are osteoarthritic changes in knee as early as one year post anterior cruciate ligament reconstruction in both the tibiofemoral and patellofemoral joints.
Over the past few years, Sports Med Res has had multiple posts (see below) regarding anterior cruciate ligament (ACL) injury as a risk factor for early-onset knee osteoarthritis (OA). Approximately 50% of knees develop radiographic evidence of OA within 10 years after ACL injury. Unfortunately, by the time we see radiographic evidence of OA there’s extensive joint damage. Magnetic resonance imaging (MRI) may be a more sensitive measure to detect earlier OA changes after an ACL injury, which may help us recognize patients to target treatment strategies to slow the onset of more joint damage. Therefore, the authors of this study wanted to determine knee OA prevalence using MRI among 111 participants 1 year after ACL reconstruction and 20 healthy matched controls. The authors used a MRI-based definition of tibiofemoral and patellofemoral OA that was developed by a panel of experts. The definition typically required the presence of two or three different types of lesions in a region (e.g., osteophyte [bone spur] and full thickness cartilage defect). MRI revealed that 31% of the participants had knee OA at 1 year post ACL reconstruction. Specifically, 21 (19%) had MRI diagnosed tibiofemoral OA, 19 (17%) had MRI diagnosed patellofemoral OA, and 67% had MRI detected osteophytes. In comparing these MRI findings to the more commonly used standard radiographs the authors found that radiographs failed to detect 86% of the MRI-based tibiofemoral OA, 79% of the MRI-based patellofemoral OA, and 66% of the osteophytes. Among the uninjured controls, no one had MRI-based OA and only 3 (15%) of knees had small osteophytes or cartilage lesions. Partial meniscectomy and being male were key risk factors for tibiofemoral and patellofemoral MRI-based OA at 1 year post ACL injury, respectively.
Significant knee OA changes are evident in MRI much earlier than previously thought. Utilizing MRI may be important for identifying, intervening, and hopefully preventing knee OA progression after an ACL injury. Osteophytes were found in an overwhelming majority of the participants at 1 year post ACL reconstruction while only a few controls had an osteophyte. The presence of osteophytes with another lesion may serve as an early indicator of impending structural changes. Interestingly as well, there is a high likelihood of early changes at the patellofemoral joint. Knee OA can start with one compartment of the knee, and then spread to affect the entire knee. Patellofemoral pain is common after ACL reconstruction, but this may be an area that deserves more attention and should not simply be dismissed as an expected limitation. The study findings are alarming in that so many knees had OA just one year after an ACL injury but these authors only investigated those after ACL reconstruction and they only had one MRI. It would be helpful to distinguish lesions that may have been caused by the injury compared with the new lesions that appeared after the injury, since these later lesions would represent progression of altered joint health. It is also important to know the knee OA prevalence in those without an ACL reconstruction because the prevalence of radiographic knee OA are comparable between those with and without a reconstruction, with some researchers proposing that ACL reconstruction can accelerate knee OA. Often times the patient is thinking about the here-and-now (e.g., returning to play) and not worrying about the long-term repercussions of their injury and how they treat the knee. We can use this study to discuss with our patients that OA is something happening right now in some knees and that we need to take steps to reduce the risk of knee OA. We need to think about not just here-and-now but about their ability to maintain a physically active lifestyle next year, the year after, and 10 years from now.
Questions for Discussion: What can clinicians do in the year following a knee injury/surgery to help a patient's long-term knee health?
Written by: Nicole Cattano
Reviewed by: Jeffrey Driban