Osteosarcoma and Malignant Fibrous Histiocytoma of Bone — Procedure Guide, Recovery & Risks | MyMedicPlus

Osteosarcoma is the most common primary malignant bone tumour, predominantly affecting adolescents and young adults during rapid skeletal growth (peak incidence 10–20 years), with a second peak in adults over 60 related to Paget disease or prior radiation. It arises most commonly in the metaphysis of long bones — distal femur, proximal tibia, and proximal humerus — and produces malignant osteoid. Malignant fibrous histiocytoma (MFH) of bone, reclassified by the WHO 2020 as undifferentiated pleomorphic sarcoma (UPS) of bone, is a high-grade sarcoma without specific line of differentiation. Both tumours are high-grade, locally destructive, and carry significant metastatic potential — primarily to the lungs. Modern management combines neoadjuvant chemotherapy, surgical resection, and adjuvant chemotherapy, achieving limb salvage in over 80% of cases at specialist centres. Malignant fibrous histiocytoma (MFH) of bone — now reclassified as undifferentiated high-grade pleomorphic sarcoma of bone — shares similar clinical behaviour and management approach with osteosarcoma, though it lacks osteoid matrix production. Both tumours require multimodal treatment integrating neoadjuvant chemotherapy, surgical resection, and adjuvant chemotherapy. MFH of bone tends to occur in older adults (median age 40–50 years) compared to osteosarcoma. Accurate pathological diagnosis distinguishing osteosarcoma from MFH, chondrosarcoma, and Ewing sarcoma is essential as chemosensitivity profiles and prognostic factors differ substantially between these entities.

Surgical resection with neoadjuvant and adjuvant chemotherapy is indicated for all patients with resectable osteosarcoma or UPS/MFH of bone without evidence of unresectable distant metastases at presentation. The majority are adolescents and young adults, but treatment protocols apply across age groups. Patients with localised disease (no detectable metastases) have the best prognosis and are treated with curative intent. Those presenting with pulmonary metastases at diagnosis may still undergo resection of both primary and metastatic deposits where technically feasible, achieving long-term survival in 20–30%. Contraindications to surgical resection include unresectable vascular or nerve involvement precluding safe wide margins, extensive metastatic burden, or severe comorbidity precluding major surgery. Amputation is reserved for cases where limb-salvage with adequate margins is not achievable without sacrificing critical neurovascular structures.

Treatment follows a trimodal approach. Neoadjuvant chemotherapy — MAP regimen (methotrexate, doxorubicin, cisplatin) or cisplatin plus doxorubicin — is administered for 8–10 weeks before surgery to reduce tumour volume, address micrometastatic disease, and allow histological assessment of tumour necrosis (a key prognostic marker). Surgical resection aims for wide clear margins (at least 1 cm of normal tissue in all planes). Limb-salvage surgery is performed in over 80% of patients: the tumour-bearing bone segment is resected and reconstructed using a modular endoprosthetic replacement (metallic implant), allograft bone, or combined allograft-prosthetic composite. The resected specimen is examined histologically to determine the percentage of tumour necrosis: greater than 90% necrosis (good response) predicts a favourable prognosis. Adjuvant chemotherapy continues post-operatively for a total of 6 cycles. Pulmonary metastases are resected via video-assisted thoracoscopic surgery where technically feasible. Surgical margins are assessed intraoperatively and on final pathology using MSTS (Musculoskeletal Tumour Society) margin classification. Reconstruction options for distal femoral tumours include modular megaprosthetic replacement, osteoarticular allografts, or composite allograft-prosthetic constructs. Pelvic osteosarcoma — particularly periacetabular — carries the highest surgical complexity, with internal hemipelvectomy or hindquarter amputation required for large tumours. Post-operative chemotherapy (adjuvant MAP) completes the treatment cycle regardless of histological response. Post-operative histological reporting drives adjuvant planning.

Modern multimodal therapy has transformed osteosarcoma from a near-universally fatal disease in the pre-chemotherapy era to one with 5-year overall survival of 60–70% for localised disease at specialist orthopaedic oncology centres. Patients with good histological response (over 90% necrosis) to neoadjuvant chemotherapy achieve 5-year survival of 70–80%, compared with 40–50% for poor responders. Limb-salvage surgery preserves functional limb use in over 80% of patients, with modern endoprostheses providing durable reconstruction and good Musculoskeletal Tumour Society (MSTS) functional scores. UPS/MFH of bone carries a similar prognosis to osteosarcoma when treated with equivalent protocols. Early-stage detection and treatment at high-volume bone tumour centres — performing 20 or more resections annually — is the strongest predictor of optimal surgical and oncological outcomes. Limb-salvage surgery offers equivalent oncological outcomes to amputation for appropriately selected patients with tumour-free surgical margins. Patients treated at high-volume sarcoma centres by experienced orthopaedic oncologists have significantly better functional outcomes and lower complication rates, underpinning the recommendation for centralised specialist care of bone sarcoma.

Surgical risks of limb-salvage resection include wound infection (5–10%), implant loosening or failure requiring revision (15–20% at 10 years), periprosthetic fracture, neurovascular injury, and limb length discrepancy in skeletally immature patients requiring expandable prostheses. Chemotherapy toxicities include nephrotoxicity from cisplatin (managed with aggressive hydration), cardiotoxicity from doxorubicin (monitored with serial echocardiography), methotrexate-induced mucositis and hepatotoxicity, and myelosuppression with infection risk. High-dose methotrexate requires leucovorin rescue and careful renal monitoring. Long-term risks include secondary malignancy from alkylating agents, anthracycline-related cardiomyopathy (cumulative dose-dependent), and infertility — fertility preservation should be discussed before chemotherapy. Local recurrence after resection occurs in 5–10% and carries a poor prognosis. Radiotherapy — not a primary treatment for osteosarcoma due to relative radioresistance — may be considered for unresectable or positive-margin cases. Wound dehiscence and skin necrosis complicate 5–10% of limb-salvage reconstructions. Secondary leukaemia is a rare but recognised late complication of osteosarcoma chemotherapy regimens.

Following limb-salvage surgery, patients are mobilised with physiotherapy within 24–48 hours of the procedure. Weight-bearing is gradually progressed over 6–12 weeks depending on reconstruction type. Full rehabilitation to restore strength, range of motion, and functional independence takes 6–12 months. Adjuvant chemotherapy cycles continue every 3 weeks for 3–4 months post-surgery, with supportive care for myelosuppression. Surveillance imaging — chest CT every 3 months for 2 years, then every 6 months — monitors for pulmonary metastases. Primary bone site is reassessed with MRI every 6 months. Expandable endoprostheses in growing children require planned lengthening procedures as the child grows. Psychological support, educational planning for adolescent patients, and physiotherapy optimisation of functional outcomes are integral to multidisciplinary care. Long-term surveillance involves clinical examination, chest CT (for pulmonary metastases — the most common site of relapse), and plain radiographs or MRI of the primary site every 3 months for 2 years, then 6-monthly to 5 years, then annually. The MSTS functional score and TESS (Toronto Extremity Salvage Score) are used to assess functional outcomes. Psychological support is integral to rehabilitation, particularly for young patients navigating body image, social development, and academic re-integration.