- Design
- Retrospective case series with age-matched controls
- Population
- 30 women, mean age 77, with bilateral distal femoral sclerotic lesions
- Primary outcome
- Radiographic, CT, MRI and histological features
- Effect
- Lateral predominance in 73% of knees; interobserver κ ≥ 0.88
A retrospective series in European Radiology (7 October 2026) described 30 women, mean age 77, with bilateral sclerotic lesions in the distal femur on knee radiographs, after excluding known skeletal disorders.
The sclerosis was usually lateral (exclusively lateral in 40%, predominantly in 33%) and linear, nodular, popcorn-like or mixed, with near-perfect agreement between readers (κ ≥ 0.88). On MRI the lesions showed a reticulonodular fibrous-like pattern within fat-signal marrow. One sampled tibial lesion showed fat necrosis with dystrophic calcification. Laboratory and clinical findings matched controls.
The value is recognition: an older woman with symmetrical sclerosis like this on knee films may be spared a work-up for metastasis or a chondroid tumour. But the series is small with histology from one lesion, so it should inform caution rather than replace standard criteria.
- Consider this benign pattern when knee films show symmetrical lateral distal femoral sclerosis in an older woman
- Look for fat-signal marrow with a reticulonodular pattern on MRI to support it
- Work up any lesion with aggressive features, asymmetry or symptoms as usual
- Compare with old films - stability supports a benign process
Why it matters
Naming a benign pattern can prevent unnecessary investigation in older patients.
Don't overread it
A descriptive series with one histological specimen - not yet a validated benign criterion.
The statistics, in plain English
High kappa values mean two readers classified the lesions consistently, not that the pattern is proven benign. Thirty patients and one biopsy are enough to describe a pattern, not to set a safe no-biopsy rule.
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