Transient osteoporosis of pregnancy involving the hips has been reported widely. The knee is much less commonly affected and only isolated cases have been reported. We report the case of a woman in the third trimester of pregnancy with bilateral transient osteoporosis of the knees.

A 36 year old woman presented with a one month history of pain in the left knee followed a week later by pain in the right. The right knee deteriorated over one to two weeks until she was unable to weight bear. There was no pain at rest. At the time of presentation she was 30 weeks pregnant with her first child conceived through in vitro fertilisation. There was no past history of joint problems, alcohol excess, corticosteroid use, preceding trauma, acute medical illness, or …