Morphology of Mouse Anterior Cruciate Ligament – Complex Changes Following Resistance Running Through Adolescence

This study aimed to understand the morphological differences within the ACL complex (i.e. the anterior cruciate ligament, insertions, and surrounding bone) in pubescent mice that voluntary ran on resistive cage wheels for 4 weeks and those exposed to normal cage activity. We tested two strains of 8-week-old, inbred mice (i.e. A/J and C57BL/6J) that collectively mirror the variation seen across the human knee. Analyses consisted of 3D morphology measurements of the knee to determine how clinical anatomical risk factors for ACL injury differed following exercise, mechanical testing of the ACL to determine if the ligament was stronger following exercise, histomorphometry to determine if the enthesis (i.e. insertion of ACL into bone) was reinforced flowing exercise, and gross and microstructural muscle differences in the gastrocnemius, quadriceps, and hamstring muscles, relative to controls. My contribution to the study was the performance of immunofluorescence to identify slow – (type 1) and fast (type IIa, IIx) twitch muscle fibers to determine how the primary muscles acting on the knee responded to resistance running. Additionally, I worked with other to toluidine blue stain and image histological sections of the knee to quantify the calcified fibrocartilaginous differences in the ACL enthesis between runners and non-runners.

Supervisor: Stephen Schlecht
Department: Orthopedic Surgery