More Horizontal ACL Posterolateral Bundle Position in Osteochondritis Dissecans of the Lateral Femoral Condyle.

BACKGROUND: The pathogenesis of osteochondritis dissecans (OCD) is multifactorial. An association of the horizontal anterior cruciate ligament (ACL) position with the anatomic proximity of its posterolateral (PL) bundle to the OCD of the lateral femoral condyle (LFC) has not been previously found.

HYPOTHESIS: In OCD of the LFC, a more horizontal ACL and PL bundle position can be found, compared to that of control patients.

METHODS: The authors retrospectively analyzed magnetic resonance imaging scans of 90 knees in 90 patients, creating 3 age- and sex-matched cohorts in a 1:1:1 ratio. Group 1 had OCD of the LFC. As controls, group 2 had OCD of the medial femoral condyle and group 3 had no structural knee pathology. Patients <18 years of age with no previous surgeries and intact ACLs were included, and patients with discoid meniscus were excluded. On the coronal plane, the height of the PL bundle insertion was measured relative to physeal height and LFC height. Femorotibial angle was also calculated to verify consistency of the measurement plane.

RESULTS: The mean age was 12.5 years (range, 8-16 years; SD, 2.24 years), with 67% male patients. There was a statistically significant difference between the height of the PL bundle insertion in patients with OCD of the LFC relative to the physis height (P < .001) and the LFC height (P < .001). The PL bundle height in group 1 was the lowest, with a mean of 0.36 (SD, 0.06) relative to the femoral condyle height and 0.46 (SD, 0.07) relative to the physeal height. In group 2, the mean relative PL bundle heights were 0.43 (SD, 0.09) and 0.50 (SD, 0.11), and in group 3, 0.43 (SD, 0.08) and 0.55 (SD, 0.11), respectively.

CONCLUSION: There is an association between a more horizontal position of the PL ACL bundle or more distal femoral attachment point of the PL bundle and OCD of the LFC. This might be a future independent factor for healing prediction of LFC OCD, and therefore its role should be studied further.

STUDY DESIGN: Case-control study; Level of evidence, 3.