follow-up of knee joint cartilage thickness changes after acute anterior
cruciate ligament rupture.

Eckstein F, Wirth W,
Lohmander LS, Hudelmaier MI, and Frobell RB. Arthritis Rheum. [Epub Ahead of Print].

Home Message:  Following an anterior
cruciate ligament (ACL) rupture overall cartilage thickness in the tibiofemoral
joint increased at an average of 0.4% per year. Patients under 25 years of age showed
greater cartilage thickening than older patients.

In addition to immediate physical limitations, a
patient who experiences an ACL rupture also has an increased risk of long-term
disability due to structural adaptations within the joint. If clinicians
could identify early changes in the joint then clinicians may eventually be
able to implement pharmacological and rehabilitation protocols to limit joint
cartilage changes and other structural changes that may lead to osteoarthritis.
Therefore, Eckstein and college completed a prospective study to quantify
tibiofemoral cartilage thickness changes in patients with an ACL rupture. The researchers
assessed 121 physically-active individuals (18-35 years old, 89 men) with ACL
ruptures who participated in the KANON randomized control trial.
Sixty-two participants underwent rehabilitation and early ACL reconstruction
(within 10 weeks of injury) and 59 participants received rehabilitation with
the option of a delayed ACL reconstruction. Sixty participants sustained
meniscal injuries in addition to the ACL rupture. The researchers measured joint
cartilage thickness changes by magnetic resonance images at baseline (4 weeks
post injury), 2 year post-injury, and 5 year post-injury. Overall, joint
cartilage thickness increased (0.4% increase per year) in the 5 year-follow
period. Participants younger than 25.3 years of age had greater annual
cartilage thickness increases compared with older participants. Cartilage
thickening was most significant in the medial tibiofemoral compartment while
cartilage thinning was noted in the posterior region of both the medial and
lateral tibia. There was some evidence to suggest that changes in joint
cartilage thickness may be more greater in some areas of the knee during the
first 2 years after an injury compared with years 3-5 post injury. 

While these findings may not impact our current day-to-day
clinical practice the data suggests that we can detect changes in the cartilage
of the tibiofemoral joint during the first 5 years after an ACL rupture. This
complements other work from the KANON trial that showed that changes in bone shape occur
over the first 5 years after an injury. While the joint cartilage overall
increased in thickness there were also areas with cartilage thinning. The areas
of thickening may represent an attempt to adapt to biomechanical changes caused
by the ACL rupture or swelling of the cartilage. These findings may suggest
that changes in the joint biomechanics may be leading to different tibiofemoral
contact points. The researchers also noted that the areas most affected may
vary between participants – it would be interesting to learn if treatment
influenced which regions were most affected. This study should serve as a
reminder to clinicians that joint injuries can have long lasting effects, like
osteoarthritis, that will cause chronic pain and disability. Traditionally,
osteoarthritis wasn’t diagnosed until years after the patient left our care but
with newer imaging approaches we can see that the changes begin while they are
still under our care. As a community focused on injury and illness prevention
we need to do everything we can to prevent these chronic conditions among our
patients. This may include promoting injury prevention programs, education
patients about the risk for osteoarthritis, and trying to optimize joint health
after an injury.
Questions for Discussion: How much does the long-term health of the knee affect your clinical
decision making in your current setting? Do you talk to your patients about the
risk of osteoarthritis after a joint injury? Do you think early detection of
change in joint health after an injury will change clinical practice?

Written by: Kyle Harris
Reviewed by: Jeffrey Driban

Related Posts:

Eckstein, F., Wirth, W., Lohmander, L., Hudelmaier, M., & Frobell, R. (2014). Five-year follow-up of knee joint cartilage thickness changes after acute anterior cruciate ligament rupture Arthritis & Rheumatology DOI: 10.1002/art.38881