Age / Sex : 77 / F

Chief complaint: right thigh pain after slip down 5 hours ago

1) What is your impression?

Two weeks later, you can see the final diagnosis with a brief discussion of this case.

(Quiz는 quiz일 뿐이오니 답안은 한개만 보내주시기 바라오며, 복수의 답안을 보내주시는 분은 정답이 포함되어 있더라도 부득이 semi-correct answer로 처리토록 하겠습니다.)

Courtesy: 이상민(Sang Min Lee), 차의과학대학교 분당차병원(Bundang Medical Center, CHA University)

Bisphosphonate related subtrochanteric insufficiency fracture

Discussion

Past history:

Fosamax? (alendronate sodium) for 15 years

Findings:

1) Plain radiography

 Incomplete transverse subtrochanteric fracture at the lateral sided proximal femora with cortical thickening, bilateral

2) CT

Asymmetrical focal cortical thickening is seen at the lateral aspect of the subtrochanteric area of the right femur with internal transverse incomplete fracture line.
 Fracture is not definitely extended to the central medullary canal and medial cortex.

3) Bone scan

Hot uptake at the lateral sided proximal femora, bilateral

Differential Diagnosis:

1) Bisphosphonate related subtrochanteric insufficiency fracture

2) Osteoporotic fracture

- Wrist, proximal part of the humerus or tibia, pelvis, and hip

3) Stress fractures

- Young military and athletes

- Obliquely oriented linear lucency within the medial cortex

4) Pathologic fractures

- Transverse and typically due to metastatic disease, Paget disease, or fractures through preexisting Looser zones

- Poorly defined lucent margins, an aggressive bone marrow pattern of destruction

- Concomitant deformity

Diagnosis:  Subtrochanteric femoral insufficiency fractures related to the use of long-term bisphosphonates

Discussion:

1) Clinical features

- No or trivial trauma history

- Prodromal symptoms of thigh pain, vague discomfort, or subjective weakness

- Misdiagnosed as degenerative change

2) Imaging findings

- Focal lateral cortical thickening at the fracture site

- Transverse fracture

- Medial spike

- Lack of comminution

- Superior displacement and varus angulation

3) Role of radiologist

- Contralateral exam and further testing

   : Bilateral in up to 67%

Excluding another cause of pathologic fracture

- Possible intervention

   : Discontinuing alendronate

Prophylactic fixation in case of contralateral fracture

References:

1) The role of the radiologist when encountering osteoporosis in women. AJR 2011;196: 331–337

2) Subtrochanteric femoral fractures in patients receiving long-term alendronate therapy: imaging features. AJR 2010;194: 1581–1586

3) Bisphosphonates and fractures of the subtrochanteric or diaphyseal femur. N Engl J Med 2010;362: 1761-1771