Purpose. To assess the association between tumour volume and occurrence of lung metastasis in patients with osteosarcoma and to determine the cut-off value. Methods.Records of 70 patients with histopathologically confirmed primary osteosarcoma in the extremities who had magnetic resonance imaging and computed tomography of the thorax less than one month before treatment were reviewed, with reference to the official report of tumour dimensions and lung metastasis by radiologists. The status of lung metastasis was assessed. Tumour volume was measured using the formula for an ellipsoidal mass. Results. Of the 70 patients with osteosarcoma, 33 (47%) had evidence of lung metastasis. Tumour volume was directly associated with occurrence of lung metastasis (p=0.048). The proportion having lung metastasis when the primary tumour volume exceeded 371 cm 3 was 69%, compared to 34% in those with smaller tumours. Conclusion. Larger tumours are more likely to

We reviewed 13 patients without an underlying syndrome with traumatic hip dislocation between 3 and 10 years of age (mean 4.8 years) at the time of injury. The final reviews were between 1 and 11 years (mean 6 years). All children had posterior dislocation, except one, who had an anterior dislocation. Time taken from trauma to reduction was less than 6 h in three patients, 6 h to 1 day in two patients, 1 day to 3 weeks in seven patients, and 4 weeks in one. All of them underwent closed reduction, except two, who required open reduction through a posterior approach. All patients had excellent hip function and radiographic result on the basis of Garret classification, except for one with limping at 4 years after trauma. The patients treated with hip spica after reduction (10 patients) did not have recurrent dislocation whereas two out of three patients who were treated without postreduction hip spica developed recurrent dislocation. One out of 13 patients without an underlying syndrome and a 6-year-old patient with Down syndrome with neglected hip dislocation and radiological avascular necrosis at presentation recovered with congruent hip following a complete and maintained reduction. This case series suggested that closed reduction was possible for cases of neglected hip dislocation for up to 3 weeks. Open reduction through the posterior approach was safe in neglected irreducible posterior hip dislocation. Those hips that underwent complete reduction and were maintained reduced with hip spica had an excellent functional outcome even in the presence of avascular necrosis. This is a level IV study.

Level IV, therapeutic study (case series). See Guidelines for Authors for a complete description of levels of evidence.

Ortolani and Barlow, Dedicated Examiner, Routine Examiner, Breech, Ultrasound.

No abstract