Courtesy: Alex Callan, MD, Assistant Professor, Orthopaedic Oncologist, UT SouthWestern Medical Centre, Dallas, Texas

 

Limb Salvage Surgery and Reconstruction in Pediatric Bone Sarcoma

Overview

• Educational discussion on bone sarcomas in children and the surgical management strategies used to preserve limb function.
• Focus on epidemiology, diagnosis, treatment pathways, limb reconstruction techniques, and rehabilitation challenges.

Learning Objectives

• Understand the causes and epidemiology of primary bone sarcomas in children.
• Review treatment strategies and multidisciplinary management.
• Discuss surgical options for local tumor control.
• Recognize rehabilitation challenges after limb salvage procedures.

Definition of Sarcoma

• Sarcoma refers to cancers originating from mesenchymal tissues.
• Mesenchymal cells give rise to bone, cartilage, muscle, fat, blood vessels, and nerves.
• Bone sarcomas are malignant tumors that arise within the skeletal system.

Epidemiology of Bone Sarcomas

• Several thousand primary bone sarcomas are diagnosed annually in large populations.
• Common pediatric bone sarcomas include osteosarcoma and Ewing sarcoma.
• Osteosarcoma is the most frequent malignant bone tumor in children and adolescents.
• Ewing sarcoma is another important pediatric bone malignancy affecting both long bones and flat bones.

Common Anatomical Locations

• Osteosarcoma frequently occurs near the knee, particularly in the distal femur or proximal tibia.
• Other common locations include the proximal humerus and pelvis.
• Ewing sarcoma commonly arises in the diaphysis of long bones.
• It may also occur in flat bones such as the pelvis, ribs, and scapula.

Radiographic Features Suggesting Aggressive Bone Tumor

• Periosteal reactions such as onion-skin appearance.
• Codman triangle caused by elevation of the periosteum.
• Sunburst pattern indicating aggressive bone formation.
• Osteoid matrix showing abnormal bone production within the lesion.

Diagnosis

• Accurate diagnosis requires imaging and biopsy.
• Radiographs help identify aggressive bone lesions.
• Magnetic resonance imaging evaluates the full extent of tumor involvement.
• Biopsy confirms the presence of malignant cells.

Staging Evaluation

• Radiograph of the entire affected bone.
• Magnetic resonance imaging of the entire bone.
• Chest imaging to detect lung metastasis.
• Whole body imaging to identify additional skeletal lesions.

Osteosarcoma Characteristics

• Most commonly occurs between ages 10 and 30.
• A second peak can occur in older adults due to secondary causes.
• Histology shows malignant spindle cells producing osteoid.
• Several subtypes exist including conventional, surface, and secondary variants.

Survival Outcomes

• Patients with localized disease have improved survival rates with modern therapy.
• Good response to chemotherapy improves long term survival.
• Presence of metastasis at diagnosis significantly reduces survival rates.

Ewing Sarcoma Characteristics

• Small round cell tumor affecting children and young adults.
• Often arises in diaphyseal regions of bones or in flat bones.
• Histology shows sheets of small round blue cells.
• Diagnosis may require molecular testing and immunohistochemistry.

Ewing Sarcoma Treatment

• Treatment typically involves chemotherapy combined with local control.
• Local control can be achieved through surgery or radiation therapy.
• Surgical removal is often preferred when feasible due to better long term control.

General Treatment Algorithm for Bone Sarcoma

• Initial chemotherapy to shrink the tumor.
• Surgical removal of the tumor with safe margins.
• Additional chemotherapy after surgery to reduce recurrence risk.

Goals of Surgical Treatment

• Complete removal of the tumor with negative margins.
• Preservation of limb function whenever possible.
• Reconstruction of bone and joints after tumor removal.

Major Surgical Reconstruction Options

• Amputation when limb preservation is not possible.
• Allograft reconstruction using donor bone.
• Endoprosthetic reconstruction using metallic implants.
• Allograft prosthetic composite combining donor bone with prosthetic components.

Amputation

• Historically the primary treatment before modern reconstruction techniques.
• Still necessary when tumors involve critical neurovascular structures.
• Prosthetic rehabilitation can allow good functional outcomes.

Allograft Reconstruction

• Uses donor bone to replace the resected segment.
• Allows preservation of native joints in some cases.
• Requires time for biological incorporation and healing.

Endoprosthetic Reconstruction

• Large metallic implants replace the removed bone segment.
• Commonly used for tumors around major joints.
• Provides immediate structural stability and early weight bearing.

Allograft Prosthetic Composite

• Combination of donor bone and prosthetic components.
• Useful when both structural support and soft tissue attachment are required.

Challenges in Limb Salvage Reconstruction

• Tumors are frequently located near joints.
• Important muscles and ligaments may need removal during tumor excision.
• Children continue to grow, creating additional reconstruction challenges.

Expandable Prostheses for Growing Children

• Special implants designed to lengthen as the child grows.
• Modern systems allow non-invasive lengthening using external magnetic devices.
• This reduces the need for repeated surgeries.

Rehabilitation Considerations

• Rehabilitation protocols vary based on tumor location and reconstruction type.
• Some patients can begin early weight bearing.
• Others require immobilization until soft tissues heal.
• Physical therapy is essential to restore function.

Common Rehabilitation Goals

• Maintain joint motion where possible.
• Prevent contractures in the knee or ankle.
• Restore walking ability and independence.
• Protect healing tissues during chemotherapy.

Complications and Challenges

• Infection risk due to long surgeries and immunosuppression from chemotherapy.
• Wound healing problems may occur during chemotherapy cycles.
• Mechanical complications such as implant failure or fractures can occur.

Multidisciplinary Care

• Management requires coordination between surgeons, oncologists, radiologists, pathologists, and rehabilitation specialists.
• Regular multidisciplinary discussions help guide treatment decisions.

Key Takeaways

• Pediatric bone sarcomas require early diagnosis and specialized treatment.
• Combined chemotherapy and surgery provide the best outcomes.
• Limb salvage surgery is increasingly possible with modern technology.
• Reconstruction techniques must consider growth, function, and long term durability.
• Rehabilitation and multidisciplinary care are essential for optimal recovery.