 Infections, chronic or acute, can affect blood flow by inducing platelet activation and aggregation, contributing to a localized state of excess coagulability (hypercoagulability) that may contribute to clot formation (thrombosis), a known cause of bone infarct and ischaemia.Exogenous estrogens, also called hormonal disruptors, have been linked with an increased tendency to clot (thrombophilia) and impaired bone healing.Heavy metals such as lead and cadmium have been implicated in osteoporosis.