MR imaging based strategies in limb salvage surgery for osteosarcoma of the distal femur

Abstract 

Objective. To analyse to what extent MR imaging based decisions were correct in determining the surgical procedure in patients with osteosarcoma of the distal femur. Design. We compared the findings on MR imaging that determined the surgical strategy with the actual surgical findings or histopathological specimen. We assessed to what extent MR images could be used to determine the surgical procedure in patients with osteosarcoma. Patients. Between 1985 and 1992, 34 patients with an osteosarcoma were treated. Two patients had a low-grade osteosarcoma. Thirty-two patients with a high-grade osteosarcoma of the distal femur (17 stage IIB, 15 stage III) were included in this study. Surgical options consisted of either limb salvage surgery or ablative surgery, which included the Van Nes-Borggreve rotationplasty. Limb salvage surgery consisted of extra-articular or transarticular resection, followed by reconstruction. Surgery was planned depending on the local extent of the tumour as depicted on the MR studies, coupled with data from the biopsy, age, patient compliance and histological grade. Follow-up was available in all patients. Nine of 17 patients graded as IIB were alive with an average follow-up of 68 months (range 46–109 months), of whom one has metastases. No local recurrence was encountered. Results. If no tumour involvement on MR imaging was found and this was used as a determining factor, this proved to be correct at subsequent analysis. We found that in eight of 11 cases, when MR images suggested a close relationship between tumour and nerve, an oncologically safe plane could be achieved during surgery. In three, a free plane could not be accomplished, as confirmed at histopathological examination. Hence, when nerve involvement was equivocal on MR imaging we found it valuable to reassess nerve involvement during surgery and reconsider limb salvage surgery. When the decisive factor was the vascular involvement and tumour extension was read as equivocal, it was possible to obtain a oncologically safe plane in six of 13 cases. When comprehensive tumour involvement of any structure was noted pre-operatively, it proved to be correct at histopathological examination, except for one case of assumed vascular involvement that proved to be free. Conclusions. If no tumour involvement of a structure was found on MR imaging and this was used as a determining factor, this proved to be correct. When nerve involvement was equivocal on MR imaging we found it valuable to reassess nerve involvement during surgery and reconsider limb salvage surgery. Extensive tumour involvement of any structure, as shown by MR imaging, could be used correctly as a decisive argument in planning a surgical procedure.