Cartilage Injury After Acute, Isolated Anterior Cruciate Ligament Tear: Immediate and Longitudinal Effect With Clinical/MRI Follow-up.
Potter HG, Jain SK, Ma Y, Black BR, Fung S, Lyman S. Am J Sports Med. 2011 Sep 27. [Epub ahead of print]
Anterior cruciate ligament (ACL) injury is common in the athletic population and has been shown to cause an immediate reduction in function and increase the risk for long term joint degeneration. In a recent review, it was reported that 0 to 39% of patients following isolated ACL injury and 40 to 90% patients with combined ACL and meniscus injury will develop knee osteoarthritis within 10 to 15 years. Currently, there is little information regarding the health of knee joint articular cartilage and underlying bone as well as its association with location and severity of long term cartilage loss following ACL injury. The purpose of this prospective longitudinal cohort study was to quantify the articular cartilage damage and bone marrow edema (similar to a bone bruise) associated with acute ACL injury (n = 42 knees), and to measure the difference in articular cartilage loss following ACL reconstruction (n = 28 patients, typically 35 years of age) when compared to patients who opted for non-operative (conservative) treatment (n = 12 patients, typically 42 years of age). Patients with secondary ligamentous injury, intrasubstance meniscal injury, or evidence of osteoarthritis were excluded from the study to reduce the influence of those injuries on the potential risk for articular cartilage loss. Within 8 weeks of injury, all patients received a magnetic resonance imaging scan to visualize the ACL disruption and observe the presence of articular cartilage loss or bone marrow edema. At baseline, 100% of patients exhibited articular cartilage damage, particularly in the lateral compartment. At 1 year follow-up, regardless of treatment choice, there was articular cartilage loss in the lateral femoral condyle, lateral tibial plateau, medial femoral condyle, and patella. When patients followed up between 7 to 11 years after injury there was further evidence of cartilage loss in the lateral femoral condyle, medial femoral condyle, and patella. Patients who opted for non-surgical treatment were more likely to exhibit articular cartilage loss in the medial tibial plateau. Finally, the size of the bone marrow edema at baseline was associated with cartilage loss during the first three years after injury.
This is the first magnetic resonance imaging study to suggest that ACL reconstruction may protect the long-term health of knee joint articular cartilage when compared to non-operative treatment. The results of similar investigations have been highly variable due to inconsistencies in the study design, operative treatment, and population included. The current results indicate that there may be substantial cartilage loss in the lateral femoral condyle, patella, and lateral tibial plateau; however, ACL reconstruction may aid in stemming the long-term effects of ACL injury. It should be noted that the participants included were, on average, 35 years old or older which is a considerably older sample than what has been included in similar previous studies. In the case of the athletic population, it can be easy to focus on the traditional 6 month progression to return to activity when designing treatment paradigms and counseling patients regarding the injury. This study makes it clear that regardless of the treatment selected, it is essential to make patients aware of the potential for long-term joint health issues with their knee. ACL injury was accompanied by articular cartilage injury and bone marrow edema in all patients and was associated with subsequent articular cartilage loss as soon as 1 to 2 years following injury. In the case of a freshman athlete, this means that they might be well on their way to OA before graduation. Does this article change your opinion of treatment for ACL injury in the recreationally active population? Does the knowledge that 100% of patients exhibited cartilage loss immediately following ACL injury change the initial treatment of similar injuries?
Written by: Chris Kuenze
Reviewed by: Jeffrey Driban
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Potter HG, Jain SK, Ma Y, Black BR, Fung S, & Lyman S (2011). Cartilage Injury After Acute, Isolated Anterior Cruciate Ligament Tear: Immediate and Longitudinal Effect With Clinical/MRI Follow-up. The American Journal of Sports Medicine PMID: 21952715
The level of evidence of articles pertaining to post ACL injury are really beginning to show the true nature and evolution of this injury. This study was particularly insightful at investigating the immediate and long-term effects to joint cartilage following an isolated ACL rupture. The findings in this study parallel earlier research done by Roos et al that also saw through radiographic imaging an immediate impact to articular cartilage following an isolated ACL tear. They also found that the extent of cartilage damage was dependent on age. Between the ages of 17-30, the onset of OA was ~15years, whereas after the age of 30 OA development has occurred with 5 years. In the current study the patient average age was over 35 suggesting there will be an increased rate of OA development. With all patients showing signs of articular damage on MRI 8 weeks after injury, the choice of treatment should be made on the basis of activity level and age. It can be inferred from the results of studies investigating OA progression after ACL injury that the choice for reconstruction will only reduce the onset of OA rather than eliminate it. From the simple fact that wearing of articular cartilage is a direct result of joint use, reduction rather than cessation of this loss is the driving force behind ACL reconstruction. On a personal level, being someone who has suffered an isolated ACL tear and opting for reconstruction, the evidence presented confirms the necessity of surgery over conservative treatment. Knowledge that 100% of patients will have a degree of cartilage damage following isolated ACL tears may suggest that injuries of this nature may also need to be surgically reconstructed to avoid the increased risk of early onset OA.
Brandon, thanks for the comment. You bring up some great points. I'm not convinced yet that there is amble evidence to universally recommend an ACL reconstruction. In studies that do direct comparisons of conservative versus surgical management we often find that both groups have about the same risk of developing knee osteoarthritis. Kyle Harris, one of the collaborators on SMR, presented a systematic review on this topic at NATA in June demonstrating this. Another interesting study was the work published by Richard Frobell et al a few months ago https://www.ncbi.nlm.nih.gov/pubmed/20660401 They concluded "In young, active adults with acute ACL tears, a strategy of rehabilitation plus early ACL reconstruction was not superior to a strategy of rehabilitation plus optional delayed ACL reconstruction. The latter strategy substantially reduced the frequency of surgical reconstructions." I believe he will have MRI and longitudinal data from this trial and that should be very informative. I think we need to find a means of identifying patients that will respond best of conservative or surgical management. Furthermore, there's a growing body of evidence to suggest that we need to find methods of reducing the risk of OA regardless of our treatment strategy. This could be evaluating the optimal time to return to play, advocating healthy lifestyles after an injury (e.g., reduce other risk factors for OA), or other interventions that might reduce the risk.
I think this article brings up a very interesting and often un-approached topic of ACL reconstruction, and that is why we do them in the first place. At least in my own clinical practice, when someone tears their ACL its more of an assumption that they will receive surgery. Having this as a justification, as well as the other multiple reasons to receive the surgery (knee stability, etc.)
Meghan, thank you for the great comment. The recent increase in research relating to importance of early reconstruction versus a more tailored approach based on the individual patient brings this issue of reconstruction as the default treatment to the forefront. This study is a great step towards assessing the long term value of a reconstruction however , as a clinician who works with the athletic population, the short term sport related benefit should also not be overlooked.