SIGNIFICANCE OF THE TUMOUR VOLUME IN PATHOLOGICAL FRACTURE

Abstract

Introduction: Mirels scoring system is a recognised method of assessing the risk of fracture in metastatic bone disease (MBD) based on radiological and clinical risk factors. Although reproducible, there are overlaps in the outcome of the scores.

Aim: The aim of this study is look at the association between the tumour volume and ratio, and the incidence of pathological fracture.

Method: Mirels score was calculated retrospectively from the patient notes. X-rays were scanned and analysed using the IMAGICA program. All tumours were measured twice on two views to the closest 0.1mm. The average of the two readings were used for the final calculations. Tumour volume was measured using 3 axis readings on the anteroposterior (AP) and lateral views of the tumour. The AP and lateral width of the tumour and the long bone shaft was measured to obtain the AP and Lateral Tumour Ratio (APTR and LTR respectively).

Results: 58 patients were admitted in 2003 with suspected primary or MBD of a long bone. 50 patients were included. 28(56%) were male. Average age was 69.2years (range 10–98years). 6(12%) patients had a lytic lesion with no fracture and 18(36%) with pathological fracture. We were unable to measure Mirels score due to poor documentation. Patients with lytic lesion and no fracture had lower APTR and LTR, 0.88 and 0.85 respectively compare with the patients with lytic fractures (APTR 0.98 and LTR 0.91). This trend was not seen in tumours with sclerotic and mixed features.

The average tumour volume was higher in the patients with lytic lesion and associated fracture than those with no fracture, 27.3 and 20.7cm³. 17(85%) of the lytic lesions, with volume larger than 10 cm³ had pathological fracture.

Conclusion: The fracture rate is higher in presence of larger tumour with higher AP and lateral tumour ratio. A single measurement of the tumour volume may be more appropriate in the assessment of a lytic lesion for pathological fracture.