Bi-lateral Proximal Tibial Osteonecrosis Mimicking Stress Fracture in a Young Adult, A Difficult Case

• Rare case of avascular Tibial osteonecrosis is described

27 year old healthy shop laborer was examined in our clinic due to severe, acute rest pain in both proximal tibiae for one week.
The anamnesis revealed recent increase in his working hours and physical load. His physical exam revealed bilateral localized metaphyseal and proximal Tibial tenderness which was more impressive in the right tibia. The patient received an adequate analgesic treatment and a complete evaluation was performed according to a preliminary diagnosis of stress fracture.

Evaluation

- X-RAY studies were unremarkable
- blood test were normal including CBC BIOCHIMESTRY, CRP, ALKP, calcium, glucose, TSH, VIT and B12.
- Technetium bone scan revealed an increasen medial uptake which was not localized to the stress fracture line.
- MRI showed an extensive involvement of both metaphysics of proximal Tibiae suggesting a bone infract

Management:

• The picture was suggestive of a rare condition and the differential diagnosis included hematological and endocrinological abnormalities was disscused. A biopsy was performed under fluoroscopy and revealed an extensive avascular osteonecrosis necrosis of the proximal tibia, No bone marrow, only adipocytes empty osteocytic lacunae and New bone tissue formation on a necrotic bone Microbiology was negative

Discussion:

• Acute Avascular necrosis of proximal tibia is a disease correlating with chronic conditions as spherocytosis, thalassemia and corticosteroid enemas in IBD patients; clearly this is not the case. It can lead to a rapid bone destruction and collapse. We suggest including idiopathic avascular Tibial necrosis in the differential diagnosis of similar rare cases