Early knee osteoarthritis is evident
one year following anterior cruciate ligament reconstruction: A magnetic
resonance imaging evaluation

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?

Nicole Cattano
by: Jeffrey Driban

Related Posts:

Culvenor, A., Collins, N., Guermazi, A., Cook, J., Vicenzino, B., Khan, K., Beck, N., van Leeuwen, J., & Crossley, K. (2014). Early knee osteoarthritis is evident one year following anterior cruciate ligament reconstruction: A magnetic resonance imaging evaluation Arthritis & Rheumatology DOI: 10.1002/art.39005