Management of sarcoma recurrence after megaprosthesis of the knee.

Background: The management of local sarcoma recurrence about the knee (at the distal femur or proximal tibia) is challenging. The objective of this study was to describe the locations of local sarcoma recurrences about knee megaprostheses, the treatments used for each type of recurrence, and the outcomes according to the treatment used.
Hypothesis: The strategy for treating a local sarcoma recurrence about the knee must be based on the topography of tumour involvement.
Materials and Methods: We included 13 patients who had local sarcoma recurrence about a knee megaprosthesis and were followed up for at least 2 years. The diagnosis was osteosarcoma in 10 patients and chondrosarcoma in 3 patients. The distal femur was involved in 11 patients and the proximal tibia in 2 patients. We classified the patients into two groups based on whether the tumour involved important structures or was at a distance within the soft tissues.
Results: The recurrence was a nodule at a distance of important structures in 8 (57%) patients, in whom the mean time to recurrence was 15 months (range, 2-34 months). The remaining 5 (38.5%) patients had involvement of important structures in the popliteal fossa and a mean time to recurrence of 42 months (range, 16-80 months). Surgery was performed in 10 patients; the other 3 patients received palliative care due to rapid metastatic dissemination. Of the 6 patients who had surgery for a recurrence at a distance from important structures, 5 (83.3%) underwent isolated tumour resection with the goal of salvaging the limb and 1 (16.7%) underwent transfemoral amputation. Transfemoral amputation was performed in all 3 patients who had surgery for popliteal recurrences. Lung metastases were detected in 10 (77%) patients, 2 at the time of initial sarcoma diagnosis and 8 at the time of the local recurrence. At last follow-up, 5 patients were alive, including 2 (33.3%) of the 6 patients with recurrences at a distance from important structures and all 3 patients with popliteal recurrences. Of the 5 survivors at last follow-up, 2 had metastases.
Conclusion: In patients with local recurrence of knee sarcoma, three presentations can be distinguished. When the local recurrence coincides with distant recurrence, failure to control the disease is likely and the local treatment should be designed as a component of palliative care. When no metastases are detected but the local recurrence is in contact with important structures, amputation is advisable at present given the complexity of limb-salvage surgery and high risk of further local recurrence. Finally, when no metastases are detected and the local recurrence is at a distance from important structures, limb-salvage surgery deserves consideration.
Level of Evidence: IV, retrospective observational study.
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