Novel Application of Magnetic Resonance Imaging Demonstrates Characteristic Differences in Vasculature at Predilection Sites of Osteochondritis Dissecans.

BACKGROUND: Understanding the pathogenesis of osteochondrosis/osteochondritis dissecans and other developmental orthopaedic diseases that are thought to occur secondary to defects in vascular supply to growth/epiphyseal cartilage has been hampered by the inability to image the vasculature in this tissue. This is particularly true in human beings due to limitations of current imaging techniques and the lack of availability of appropriate cadaveric samples for histological studies. HYPOTHESIS: Susceptibility-weighted imaging, an MRI sequence, allows identification of characteristic differences in the vascular architecture in species that are affected by osteochondrosis/osteochondritis dissecans on the femoral condyle (humans and pigs) versus a species that is free of the disease (goat). STUDY
DESIGN: Controlled laboratory study. MATERIALS: Distal femora from cadavers of juvenile humans (n = 5), pigs (n = 3), and goats (n = 3) were scanned in a 9.4-T MRI scanner using susceptibility-weighted imaging. Three-dimensional reconstructions were created, and minimum intensity projections were calculated in 3 planes to enhance visualization of the vascular architecture.
RESULTS: Susceptibility-weighted imaging allowed clear visualization of the epiphyseal vasculature in all species. Vascular architecture, with vessels primarily arising from the perichondrium, was similar in humans and pigs, which are predisposed to osteochondrosis/osteochondritis dissecans, and was starkly different from that present in goats, a species in which there are no reports of osteochondrosis/osteochondritis dissecans. Furthermore, vessels in the distal femoral predilection site disappeared with age in humans in a pattern similar to that reported previously in pigs.
CONCLUSION: Nearly identical vascular architecture at the shared primary predilection site of osteochondrosis/osteochondritis dissecans in the femoral condyles in human beings and pigs suggests that vascular failure, which is known to be central to the pathogenesis of this disease in pigs, may also play a role in humans. CLINICAL RELEVANCE: This assumption of a shared pathogenesis is supported by the pattern of disappearance of vessels with age at the primary predilection site of osteochondritis dissecans in humans, which is essentially identical to that which has been reported in pigs. Susceptibility-weighted imaging will likely help further elucidate this potential relationship in the future.