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Few studies examining the predisposing anatomical factors leading to anterior cruciate ligament (ACL) injuries have examined the ACL itself, and none of these directly examined the difference in ACL properties between injured and matched control subjects. This case–control study hypothesises that the ACL total volume in people who have experienced a non- contact ACL injury is smaller than that of matched controls. This study has a level of evidence of 3. Contours of the ACL were manually

identified in sagittal magnetic resonance imaging (MRI) scans and volumes were calculated for 27 contralateral healthy knees of individuals after non-contact ACL

ANTERIOR CRUCIATE LIGAMENT-INJURED SUBJECTS HAVE SMALLER ANTERIOR CRUCIATE LIGAMENTS THAN MATCHED CONTROLS: A MAGNETIC RESONANCE IMAGING STUDY. Chaudhari AM, Zelman EA, Flanigan DC, Kaeding CC, Nagaraja HN. American Journal of Sports Medicine 2009;37:1282–1287.

injury and for 27 control subjects matched for gender, height, age and weight. Validation of this method was performed on five porcine knees. Results: Contralateral ACL volume for injured subjects was significantly smaller than for non- injured subjects by 231mm3, after adjusting for weight, which was also a significant contributor to ACL volume. At the average body mass of 72.7kg, subjects with a non-contact ACL injury had an average contralateral ACL volume of 1921mm3, while the corresponding control group had an average volume of 2151mm3. Gender, height and age were not significant

when weight was included in the regression model.

sportEX comment This raises an interesting ethical

issue. The study shows that there are anthropometric differences between the knees of subjects with a non-contact ACL injury and those without an ACL injury, suggesting that ACL volume may play a direct role in non- contact ACL injury. So, should we be screening out athletes with the potential for injury via MRI scans? Discuss.

INCREASING INCIDENCE OF MEDIAL MENISCAL TEARS IN NONOPERATIVELY TREATED ANTERIOR CRUCIATE LIGAMENT INSUFFICIENCY PATIENTS DOCUMENTED BY SERIAL MAGNETIC RESONANCE IMAGING STUDIES. Yoo JC, Ahn JH, Lee SH, Yoon YC. American Journal of Sports Medicine 2009;37:1478–1483.

No consensus has been reached with regard to the

ideal timing of anterior cruciate ligament (ACL) reconstruction in terms of reducing secondary meniscal tears in ACL- deficient knees. This article hypothesises that a delay in ACL reconstruction increases the incidence and severity of medial meniscal tears. Thirty-one patients were evaluated with arthroscopic all-inside suturing of medial meniscal tears with concurrent ACL reconstruction. Each patient had at least two preoperative magnetic resonance imaging (MRI) scans. Patients were evaluated during the acute phase of injury, but ACL reconstruction surgery

was delayed for at least 6 months. The mean interval between first and second imaging studies was 36.8 months. Relationships between medial meniscal lesions and patient age, time interval between the date of initial injury and surgery, repetitive injury and patient activity level were evaluated. Results: During the first preoperative MRI study, 14 knees had no medial meniscal tear, 15 a longitudinal tear, and 2 a bucket-handle- type tear. During the second preoperative MRI study, 5 knees had no medial meniscal tear, 19 knees a longitudinal tear and 7 knees a bucket-handle-type tear. The incidence of medial meniscal tears increased from 55% in the first study to 84% in the second study for chronic ACL-insufficient knees. Eight knees

without a tear during the first study had a longitudinal tear during the second study. One knee without a tear and four knees with a longitudinal tear in the first study had a bucket-handle-type tear in the second study. Thirteen knees (42%) had a worse meniscal status during the second study.

sportEX comment The findings show that further medial meniscal damage is common if surgery is delayed by 6 months or more. The study suggests, therefore, that early ACL reconstruction should reduce or prevent additional medial meniscal injury.

The aim of this systematic review was to

determine the diagnostic accuracy of tests to identify the disc, facet joint or sacroiliac joint (SIJ) as the source of low back pain. The main databases were searched with a cut-off date of February 2006. Forty-one studies of moderate quality were included: 28 investigated the disc, 8 the facet joint and 7 the SIJ. Results: Various features observed on magnetic resonance imaging (MRI) (high- intensity zone, endplate changes and disc degeneration) proved informative in the majority of studies, increasing the

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SYSTEMATIC REVIEW OF TESTS TO IDENTIFY THE DISC, SIJ OR FACET JOINT AS THE SOURCE OF LOW BACK PAIN. Hancock MJ, Maher CG, Latimer J, Spindler MF, et al European Spine Journal 2007;16:1539–1550.

probability of the disc being the source of low back pain but, heterogeneity prevented pooling of the data. Centralisation was the only clinical feature found to increase the likelihood of the disc as the source of pain. Absence of degeneration on MRI was the only test found to reduce the likelihood of the disc as the source of pain. Although single manual tests of the SIJ were uninformative, their use in combination was informative. None of the tests for facet joint pain was found to be informative.

sportEX comment This supports the current trend of clinicians not being specific about the underlying source of low back pain. The truth is that manual tests alone are not necessarily going to pinpoint the source as disc or SIJ, and they are definitely not going to demonstrate facet joints as a source. To quote the authors, “usefulness of these tests in clinical practice, particularly for guiding treatment selection, remains unclear”.

sportEX medicine 2009;42(Oct):4-6