Structural, functional, and proteomic based sex differences in murine post-traumatic osteoarthritis development following mechanical anterior cruciate ligament injury.

OBJECTIVE

Post-traumatic osteoarthritis (PTOA) is known to be influenced by sex. This study aimed to comprehensively characterize PTOA development in male and female mice following anterior cruciate ligament (ACL) injury through longitudinal mobility assessments, radiographic imaging, histologic evaluation, and untargeted proteomics.

DESIGN

At 12 weeks of age, 110 C57BL6J mice (55 males, 55 females) underwent unilateral mechanical ACL rupture to induce PTOA. 30 mice (15 males, 15 females) served as naïve controls. Symptoms of PTOA development were assessed weekly for 56 days post-injury through voluntary cage monitoring, gait analysis, and static weight bearing. PTOA pathology was evaluated through longitudinal radiographs and histopathology at multiple endpoints. ACL proteomes were analyzed using untargeted label-free protein quantification at 3, 7, and 14 days post-injury, with intact ACLs serving as controls.

RESULTS

Post-injury, male mice showed significant reductions in overall activity compared to females, including decreased head distance traveled (mean difference 56d: -3.81[95%CI:-7.45 to -0.18]). Males exhibited wider hindlimb stance (mean difference 56d: 0.28[95%CI:0.01 to 0.56]) and persistent hindlimb offloading (mean difference 56d: 0.30[95%CI:0.08 to 0.52]). Longitudinal radiographic analysis revealed no significant sex-based differences. Histological assessments revealed more severe joint pathology in males (mean difference 56d: 49.97[95%CI:5.78 to 94.15]). Females also demonstrated a robust proteomic response peaking at 3 days, with notable pathways related to inflammation, the coagulation cascade, and estrogen signaling.

CONCLUSION

This study revealed increased progression of PTOA in male mice, evidenced by mobility impairments, worsened histologic scores, and divergent proteomic responses. These insights will enhance future research on therapeutic strategies for PTOA prevention.