Introduction:
Transient osteoporosis of pregnancy is a rare metabolic bone disorder, characterised by pain, with bone-marrow oedema on imaging.1 It affects 1 in 4900 pregnancies with a 25.7% risk of fractures.2 There is significant decline in bone mineral density during pregnancy, but the pathophysiology remains unknown.
Case Summary:
A 29-year-old, G2P0, presented with 8-weeks of atraumatic, progressively worsening bilateral hip pain at 30-weeks of gestation on background of 5-pack-year history of smoking and no family history of osteoporosis. She had reduced movement at the hip bilaterally and her systemic examination was unremarkable.
Investigations revealed a normal full blood count, corrected Calcium of 2.56mml/L, phosphate 1.08mmol/L and ALP 173unit/L. Pelvic X-ray did not reveal any fractures. MRI showed symmetrical bone-marrow oedema in bilateral femoral heads and necks, in keeping with transient osteoporosis of the hips. She delivered via Caesarean-section to minimize risk of fractures. Secondary osteoporosis screen was normal. Bone-turnover markers were: CTx 1160ng/L and P1NP 137ug/L. Post-partum bone mineral densitometry was consistent with osteoporosis. She was managed with regular analgesia, non-weight bearing status initially, which was transitioned to protected weight bearing, regular physiotherapy, vitamin D and calcium supplementation. A single dose of Pamidronate was administered with significant improvement in her pain.
Conclusion:
Transient osteoporosis of the hip in pregnancy is underdiagnosed.3 There is substantial morbidity and mortality associated with this condition. Early diagnosis is key to minimise fractures. The use of anti-resorptive medication has been used successfully to minimise duration and severity of symptoms, but data is limited.