Intrinsic Stresses on Bone and Cartilage in the Normal and Anterior Cruciate Ligament–Reconstructed Knee Before and After a Half Marathon

Objective To investigate intrinsic changes of the anterior cruciate ligament-reconstructed and control (contralateral) knees after a half marathon. Design Prospective case series. Setting Sports Medicine Clinic. Participants Eight runners were included in the analysis. Interventions Magnetic resonance imaging (MRI) of both knees within 48 hours before and after competition. Participants completed the Tegner Activity Level Scale and a Knee Demographic Questionnaire before the preevent MRI scan. Main outcome measures The incidence of MRI-identified cartilage, ligament, bone, and meniscus pathology in the ACL-reconstructed and control knees. Results The control knees of 5 runners (63%) demonstrated cartilage lesions, but no change was evident on postevent MRI. Preevent MRI in ACL-reconstructed knees demonstrated Grade IV meniscal lesions (4 of 8), Grades II (2 of 8) and IV cartilage lesions (4 of 8), and Type I bony edema (4 of 8). Although not significant, ACL-reconstructed knees demonstrated a strong trend (P = 0.01) toward a greater incidence of bone marrow edema on postevent MRIs compared with control knees. Conclusions This is the first study to compare the effects of running on intrinsic structures of a normal and ACL-reconstructed knee. Reconstructed knees demonstrated a greater incidence of bone marrow edema on postevent scans, but knee pathology evident on preevent scans did not progress in either control or ACL-reconstructed knees.