osteoporosis — SAQ

Stem

A 72-year-old woman presents after slipping at home: she fell from a standing height and could not stand afterwards. On examination the right leg is shortened and externally rotated, and she cannot weight-bear. She has lost 5 cm of height over recent years and has a thoracic kyphosis. Menopause was at age 49; she has never taken hormone replacement. She smoked 15 cigarettes a day for 40 years, drinks little milk, and takes no medications or supplements. A pelvic X-ray confirms a displaced right femoral neck fracture. Her serum calcium, phosphate, alkaline phosphatase, renal function and TSH are normal; 25-hydroxy vitamin D is 32 nmol per litre.

Questions

a) What is the unifying diagnosis, and which single bedside investigation quantifies its severity? (2 marks)

Model answer: Osteoporosis complicated by a low-trauma (fragility) hip fracture (1 mark). The fragility fracture alone establishes the diagnosis; severity and formal diagnosis are quantified and confirmed by DEXA of the lumbar spine and hip, reported as the T-score (1 mark).

b) Define the DEXA T-score thresholds for osteoporosis and osteopenia, and state how a fragility fracture alters interpretation. (2 marks)

Model answer: Osteoporosis = T-score of minus 2.5 or less; osteopenia = T-score minus 1.0 to minus 2.5 (1 mark). A low-trauma (fragility) fracture establishes the diagnosis of osteoporosis regardless of the T-score, so treatment is indicated even if the score falls in the osteopenic range (1 mark).

c) Outline the non-pharmacological and first-line pharmacological management once the hip is fixed. (4 marks)

Model answer: Non-pharmacological: weight-bearing and resistance exercise, smoking cessation, limit alcohol, fall-prevention advice and home-hazard reduction, and adequate calcium (1000 to 1200 mg per day) with vitamin D (800 to 1000 IU per day; correct her low vitamin D) (2 marks). First-line drug therapy: an oral bisphosphonate such as alendronate weekly (or IV zoledronate annually), which reduces vertebral, hip and non-vertebral fractures (2 marks). Calcium and vitamin D must be ensured before and during bisphosphonate therapy.

d) After three to five years of a bisphosphonate she remains well with a stable T-score. What is the concept of a drug holiday, and what two rare complications of long-term bisphosphonate therapy does it balance? (2 marks)

Model answer: A drug holiday is a planned interruption of the bisphosphonate after 3 to 5 years in a stable, lower-risk patient, exploiting its prolonged skeletal retention while monitoring with DEXA (1 mark). It balances the continued fracture protection against the rare risks of atypical femoral fracture and osteonecrosis of the jaw (1 mark). She would be reassessed and the drug resumed if fracture risk rises or bone density falls.