Intraoperative Fragile Bone and Radiographic Sclerosis in Skeletal Fluorosis Case

Overview

This case report describes a 59-year-old woman with skeletal fluorosis undergoing staged bilateral total knee arthroplasty (TKA). Despite preoperative radiographs showing increased bone density and sclerosis, intraoperative findings revealed severe osteoporosis and fragile bone, complicating surgical exposure and increasing fracture risk.

Background

Skeletal fluorosis is a toxic osteopathy caused by prolonged ingestion or inhalation of high fluoride levels, leading to bone and joint pain, stiffness, and deformities. Radiographically, it manifests as osteocondensation, ligament ossification, and cortical thickening, but these imaging findings do not always correlate with bone quality. The disease is endemic in certain regions with high fluoride exposure and can be misdiagnosed due to its subtle clinical presentation.

Data Highlights

Preoperative radiographs showed varus deformity, osteophyte formation, increased bone density, thickened and fused trabeculae, thickened cortical bone, and narrowed marrow cavity. Urinary fluoride level was 0.62 mg/L (reference <1.6 mg/L). Intraoperatively, bone was severely osteoporotic with thin cortical bone, sparse trabeculae, and bone cysts, indicating low resistance to sawing and drilling. Hospital for Special Surgery (HSS) knee scores improved from 54 to 76 (right knee) and 58 to 88 (left knee) one week postoperatively.

Key Findings

• Preoperative radiographs demonstrated increased bone density and sclerosis typical of skeletal fluorosis.
• Intraoperative assessment revealed paradoxical severe osteoporosis despite radiographic sclerosis.
• Calcification and ossification of ligaments, capsules, and interosseous membranes complicated surgical exposure.
• Low bone resistance necessitated careful surgical techniques with low drilling torque and gentle handling to avoid fractures.
• Postoperative functional outcomes improved significantly with early mobilization and rehabilitation.
• Clinicians should recognize that radiographic sclerosis in skeletal fluorosis does not preclude fragile bone quality intraoperatively.

Clinical Implications

Preoperative evaluation of bone quality and soft tissue flexibility is critical in patients from endemic fluorosis areas to anticipate surgical challenges. Surgeons should prepare for fragile bone despite radiographic sclerosis and employ gentle exposure and bone preparation techniques to minimize fracture risk. Awareness of this paradox can improve operative planning and patient outcomes.

Conclusion

Skeletal fluorosis can present with radiographic sclerosis masking underlying severe osteoporosis, posing intraoperative challenges during joint arthroplasty. Comprehensive preoperative assessment and tailored surgical strategies are essential for successful management.

References

1. Hagen and Grinsberg 1980 -- Radiographic Stages of Skeletal Fluorosis
2. Case Report 2024 -- Intraoperative Fragile Bone and Radiographic Sclerosis in Skeletal Fluorosis