Osteoarthritis severity is sex dependent in a surgical mouse model.

Objective: To investigate the role of sex hormones in cartilage degradation and progression of osteoarthritis (OA) in a murine model induced by destabilization of the medial meniscus (DMM).

Design: Accelerated OA development in mice was induced by transection of the menisco-tibial ligament, which anchors the medial meniscus to the tibial plateau. Intact male and female, and orchiectomized (ORX) male and ovariectomized (OVX) female mouse knee histology were compared for signs of OA following DMM. The effect of testosterone or estrogen addition in vivo was assessed in ORX males in the surgical OA model.

Results: OA severity was markedly higher in males than females after DMM. OVX females developed significantly more severe OA than control females. ORX males developed significantly less severe OA than control males. When ORX male mice were supplemented with exogenous dihydrotestosterone (DHT), the severity of OA was restored to the level experienced by the control male mice. Hip cartilage from mice of both sexes demonstrated similar spontaneous and interleukin-1alpha (IL-1alpha) induced proteoglycan (PG) release in vitro. DHT and 17-beta estradiol (E2) did not significantly alter the PG release pattern when supplemented to cartilage cultures of either sex.

Conclusion: Sex hormones play a critical role in the progression of OA in the murine DMM surgical model, with males having more severe OA than females. Intact females had more OA than OVX females, indicating that ovarian hormones decrease the severity of OA in the female mice. Male hormones, such as testosterone, exacerbate OA in male mice as demonstrated by the fact that ORX mice experienced less OA than intact males, and that addition of DHT to ORX males was able to counteract the effect of castration and re-establish severe OA.