QUANTITATIVE ANALYSIS OF THE VASCULARITY OF SKELETALLY IMMATURE FEMORAL CONDYLES: A CADAVER STUDY USING CONTRAST-ENHANCED MAGNETIC RESONANCE IMAGING
Authors: Lazaro Lionel E. , Gadnisky Naomi , Klinger Craig , Dyke Jonathan P. , Kleeblad Laura J. , Shea Kevin , Helfet David , Rodeo Scott A. , Green Daniel W. 
Published: March 2019

Background: The arterial supply to the chondroepiphysis is of paramount importance for proper nutrition and development. Previous animal studies had demonstrated that ischemic necrosis of the chondroepiphysis plays an important role in subsequent development of osteochondritis dissecans (OCD). Previous studies using susceptibility weighted imaging, a magnetic resonance image (MRI) sequence, demonstrated a pattern of disappearance of the arterial system over time at predilection sites for OCD lesions. The purposed of this study is to quantify distribution of the arterial perfusion in different zones of the immature distal femoral chondroepiphysis. Methods: We utilized 5 fresh frozen skeletally immature human cadaver knees (aged 0-6 months). The superficial femoral artery was cannulated proximal to the knee joint and major arteries distal to the knee joint were tied off. For volumetric analysis, comparisons were performed between contrast-enhanced and pre-contrast MRI. Regions of interest were developed to quantify the contrast enhancement in different zones of the chondroepiphysis, excluding the secondary ossification center. (Fig.1) Results: Quantitative MRI analysis demonstrated equivalent enhancement within the medial and lateral condyles in the 5 month and one of the 2 month specimens. The 0 month and 6 month specimens demonstrated greater enhancement in the medial condyle. One of the 2 months specimen demonstrated greater perfusion in the lateral condyle. The distal condyle analysis demonstrated equivalent enhancement in the 0 month, one of the 2 months and the 6 months specimens. The 5 month specimen demonstrated greater enhancement in the lateral distal condyle. The other 2 months specimen demonstrated greater enhancement in the medial distal condyle. The posterior condyle analysis demonstrated greater enhancement in the posterior lateral condyle in one of the 2 month specimen, and the 5 month and the 6 month specimens. The 0 month specimen demonstrated greater enhancement in the medial side. The other 2 month specimen demonstrated equivalent enhancement between medial and lateral side. Analyzing the medial condyle revealed equivalent enhancement in the medial and lateral zone in the 5 month and 6 month specimens. The 0 month specimen demonstrated greater enhancement laterally. Both 2 months specimens demonstrated greater enhancement in the medial side. Conclusion: This study expands the knowledge on the vascularity of the developing distal femoral chondroepiphysis, which may have an impact on our future understanding of OCD etiology, physeal growth, and peri-articular infections. The majority of the specimens demonstrated diminished perfusion in the posterior aspect of the medial femoral condyle when compare to the lateral posterior condyle. This is where the predilected area for the development of OCD lesions is located. Future studies in human and other mammals susceptible to knee OCD, along with the ongoing development of animal models of OCD will benefit from this information.