Articular cartilage compressive stiffness following oophorectomy or treatment with 17 beta-estradiol in young postpubertal rabbits

Background Changes in estrogen concentrations during adolescence (contracep tives, secondary amenorrhea) may influence cartilage mechanics and therefor e its capacity to respond adequately to physical demands. The purpose of th is study was to investigate the influence of oophorectomy or continuous adm inistration of estradiol on cartilage compressive properties in an immature animal model. Methods. Young postpubertal female New Zealand white rabbits wept tither oo phorectomized (n=9) or underwent a sham-operation (n=8). The sham-operated animals received in addition a daily dosage of 4 mg 17 beta-estradiol orall y starting 3 weeks after surgery until death. After 5 months the animals we re killed, and cartilage compressive properties (ramp and creep moduli) wer e determined at 4 defined knee joint regions by in situ indentation tests. Five age-matched rabbits were used as controls. Results. Femoral cartilage stiffness (ramp and 15-s creep moduli) and thick ness in oophorectomized animals were significantly higher than those in con trols or estradiol-treated animals (p<0.05 and less), but there was no diff erence between the latter groups. Tibial cartilage showed less obvious trea tment-dependent differences. The cartilage in the medial compartment was th icker than in the lateral one, and femoral cartilage was thinner than tibia l cartilage (p<0.00805), irrespective of the treatment. Conclusions. Oophorectomy during adolescence led to increased femoral carti lage thickness and stiffness. The relevance of these findings for the devel opment of cartilage disease has to be elucidated in the future.