Bone bruise not linked to pain or symptoms at index ACL reconstruction

Dunn WR. Am J Sports Med. doi:10.1177/0363546510370279.

The risk factors associated with a bone bruise after ACL injury are younger age and not jumping at the time of injury, according to cohort study results.

The Multicenter Orthopaedic Outcomes Network (MOON) database began prospectively collecting surgeon-reported MRI bone bruise status in 2007. Warren R. Dunn, MD, MPH, Vanderbilt University Medical School, Nashville, Tenn., and colleagues used linear multiple regression models to examine the association of a bone bruise with knee pain or symptoms. These models used the continuous scores of the Knee Injury and Osteoarthritis Outcome Score (KOOS) symptoms and pain subscales as well as the Short Form-36 (SF-36) bodily pain subscale as dependent variables.

The researchers used a logistic regression model to study the association between a bone bruise and risk factors; in this case, the dependent variable was the presence or absence of a bone bruise.

Of the 525 patients for whom baseline data were available, 419 (80%) had a bone bruise. Fifty-eight percent of the cohort were men; median age was 23 years.

Dunn and colleagues found that a higher body mass index (P<.0001), female sex (P=.001), lateral collateral ligament injury (P=.012) and older age (P=.038) were associated with more pain. A concomitant lateral collateral ligament injury (P=.014), a higher body mass index (P<.0001) and female sex (P<.0001) were associated with more symptoms. There was no link between bone bruise and symptoms or pain at the time of index ACL reconstruction. No SF-36 bodily pain model factors were significant.

Pain in this article is defined as the results on subsets of known outcome scales (KOOS pain and symptom subscales and SF-36 bodily pain subscale). Several preoperative variables were examined, including bone bruise, which occurred in 80% of this population. Other factors that could be associated with pain at the time of surgery include the surgery timing in relation to the index injury, concomitant medication, knee swelling, etc.

Given that standard MOON guidelines were in place as a prerequisite of surgery (regain range of motion, normal gait, etc.), to me the more intriguing factor is that patients still have clinically relevant pain levels at the time of index ACL reconstruction as assessed by their outcome subscales, unrelated to intra-articular comorbidity. The authors of this study centered their research findings on one of dozens of preoperative variables — bone bruise — which seems not to be as relevant.

– Elizabeth A. Arendt, MD
Professor
Department of Orthopaedic Surgery
University of Minnesota
Minneapolis, Minn.