Fibrous Dysplasia

Modern Study Review (AI-Generated)

High-Yield Summary

Fibrous dysplasia (FD) is a benign, developmental bone disorder characterized by replacement of normal bone with immature woven bone and fibrous stroma, leading to structural weakness and deformity. It commonly presents in adolescence or early adulthood and can be monostotic (single bone) or polyostotic (multiple bones), with the latter sometimes associated with McCune-Albright syndrome. Diagnosis relies on characteristic radiographic features and clinical presentation, while treatment focuses on symptom management, fracture prevention, and correction of deformities.

Key Diagnostic Findings

Anatomy

• FD affects the medullary cavity of bones, replacing normal lamellar bone with immature woven bone and fibrous tissue.
• Commonly involved sites include the proximal femur, ribs, craniofacial bones, and long bones.

Clinical Presentation

• Age of onset: Typically 2nd to 3rd decade of life.
• Symptoms: Localized pain, swelling, and tenderness at the lesion site.
• Deformities: Bowing deformities such as the classic “shepherd’s crook” deformity of the proximal femur.
• Polyostotic FD may present with endocrinopathies and café-au-lait spots (McCune-Albright syndrome).

Imaging

Histology

• Fibro-osseous lesion with irregular trabeculae of woven bone in a fibrous stroma.
• Lack of osteoblastic rimming distinguishes FD from osteofibrous dysplasia.

Classification Systems

• No formal staging system universally used; clinical distinction between monostotic and polyostotic forms is critical.
• McCune-Albright syndrome is a recognized polyostotic variant with systemic manifestations.

Current Gold Standard Treatment

Non-operative

• Observation for asymptomatic, non-weightbearing lesions without deformity or fracture risk.
• Pain management with analgesics and activity modification.
• Bisphosphonates may be considered to reduce bone pain and turnover, though evidence is mixed.

Operative

• Indicated for weightbearing bones with deformity, pathological fractures, or functional impairment.
• Procedures include internal fixation with intramedullary nails or plates and bone grafting (preferably cortical strut grafts).
• Corrective osteotomies for deformity (e.g., shepherd’s crook) may be necessary.
• Sarcomatous transformation is rare but requires oncologic resection.

Modern Complications & Outcomes

Complications

Outcomes

• Prognosis is generally good with appropriate management.
• Pain and function improve with stabilization and deformity correction.
• Long-term monitoring is essential for deformity progression and rare malignant transformation.
• Bisphosphonate therapy may reduce pain but does not reverse deformity.

Classic Clinical Notes

Fibrous Dysplasia

• Dysplastic disorder of bone characterized by presence of trabeculae of immature bone at 1 or many sites.
• Represents disordered bone maturation & often results in progressive bony deformity that may be associated with pathological fractures.
• Presents in 2nd or 3rd decade.
• Albright’s syndrome – polyostotic variant associated with precocious puberty & café-au-lait spots.

Signs & Symptoms

• Pain with tenderness & swelling at the site of the lesion (monostotic vs polyostotic).

X-rays

• ‘Ground glass’ appearance.
• Well-defined marginated lesion with rim of sclerotic bone.
• Expansion, endosteal scalloping & deformity of affected bone.
• ‘Shepherd’s crook’ – classic deformity of proximal femur arising from bowing of bone & many pathologic fractures.

Histology

• Collagenous matrix containing proliferating fibroblasts in haphazard pattern.
• Paucity of osteoblasts surrounding bony trabeculae ? distinguishes it from osteofibrous dysplasia.

Treatment

• Non-weightbearing skeleton – observation.
• Weightbearing skeleton – internal fixation & bone grafting.
• Sarcomatous transformation – occasional in polyostotic form.

Last Updated on January 25, 2026 by orthonet