Anterior cruciate ligament injury: post-traumatic bone marrow oedema correlates with long-term prognosis.
Filardo G, Kon E, Tentoni F, Andriolo L, Di Martino A, Busacca M, Di Matteo B, and Marcacci M. Int Orthop. 2015. [Epub Ahead of Print]
Take Home Message: Knees with bone marrow oedema 3 or more months after an anterior cruciate ligament injury are less likely to return to activity when compared with knees without oedema.
Bone marrow oedema (BME) is commonly seen on magnetic resonance (MR) images among knees with an anterior cruciate ligament (ACL) rupture. In these cases, BME is often referred to as a bone bruise or bone contusion. BME patterns may relate to the mechanism and severity of injury. It remains unclear if BME may be predictive of patient outcomes years after an injury. Understanding this would help clinicians better communicate the long-term expectations to their patients following an ACL injury. Therefore, Filardo and colleagues completed a retrospective cohort study to assess the relationship between BME shortly after an ACL injury and return to play as well as clinical outcomes at least 5 years after an injury. The authors selected 134 patients (98 men, ~32 years old) who had an ACL tear, were between 16 and 50 years of age at the time of their MR imaging, underwent an MR scan within 6 months of injury, and had a clinical follow-up at least 5 years after the injury. Fifty percent of the patients underwent an ACL reconstruction. Two independent and blinded reviewers evaluated the MR images for BME presence and size. Patient outcomes were assessed using the International Knee Documentation Committee Subjective Knee Form and Tegner activity score. Overall, the readers found that 65% of knees with an MR scan within 3 months of injury had a BME while only 25% of knees had BME when scanned after 3 months post-injury. Among the patients who had an MRI after 3 months post-injury, the authors found that everyone with BME failed to achieve full return to pre-injury levels of sport. In contrast, 54% of patients who had a later MR scan and had no BME were able to achieve at least 90% of their pre-injury level of sport competition. A similar pattern was also observed when the authors only evaluated patients who underwent an ACL reconstruction, regardless of when the MR scan was acquired.
Overall, the current study is interesting because the findings suggest that BME that lingers beyond 3 months after an injury may be a bad sign for an individual’s ability to return to his/her pre-injury levels of activity. In a previous Sports Med Res post we described a study that showed that BME usually diminishes within 12 months of injury. Knees with BME that persist for 3 months or longer may have experienced a greater injury, which could explain the poorer outcomes. Interestingly, the study in the previous Sports Med Res post found that about a third of knees redeveloped bone marrow lesions. This was concerning since these lesions are often associated with osteoarthritis progression. The prior study as well as the study reported here raises questions about whether we should be getting follow-up MR imaging on our patients 3-24 months after an injury. Future analysis may help clinicians better understand how changes in BME after an injury could inform long-term outcomes. It is important to appreciate that in this retrospective study the individuals getting MR images 3 months after an injury may be experiencing joint problems that prompted a physician to order the images. Improving our understanding of the relationship between BME changes and long-term outcomes could lead to the development of guidelines to treat patients based on the severity of the BME to better preserve the long-term health of the joint. Until this time, BME can be used to help advise patients with regards to their long-term prognosis regarding their return to their desired or previous level of physical activity.
Questions for Discussion: Do you ever get MR images on your athletes 3-24 months after an ACL injury? Do you think bone bruises in knees with ACL injuries can help us determine a patient's prognosis?
Written by: Kyle Harris
Reviewed by: Jeffrey Driban
Factors Used to Determine Return to Unrestricted Sports Activities After Anterior Cruciate Ligament Reconstruction