Osteoporosis

Definition

Osteoporosis is a chronic condition characterised by reduced bone mass and deterioration of bone tissue, leading to increased bone fragility and susceptibility to fractures. It is often referred to as a "silent disease" because it typically progresses without symptoms until a fracture occurs.

Aetiology

Osteoporosis can be primary or secondary:

Primary Osteoporosis: Includes postmenopausal osteoporosis and age-related osteoporosis.
Secondary Osteoporosis: Results from underlying medical conditions or medications, such as chronic glucocorticoid therapy, hyperthyroidism, and malabsorption syndromes.

Pathophysiology

Bone is a dynamic tissue that undergoes continuous remodelling through the processes of bone resorption and formation. Osteoporosis occurs when bone resorption outpaces bone formation, leading to a net loss of bone mass. This imbalance can be influenced by hormonal changes, particularly decreased oestrogen levels in postmenopausal women, and by insufficient intake or absorption of calcium and vitamin D.

Risk Factors

Advanced age
Female gender
Family history of osteoporosis or fractures
Menopause
Low body weight or body mass index (BMI)
Calcium and vitamin D deficiency
Smoking
Excessive alcohol consumption
Physical inactivity
Chronic use of glucocorticoids
Medical conditions such as rheumatoid arthritis, hyperthyroidism, and malabsorption syndromes

Signs and Symptoms

Osteoporosis often remains asymptomatic until a fracture occurs. Common signs and symptoms include:

Fractures, particularly of the hip, spine, and wrist
Loss of height over time
Stooped posture
Back pain, caused by a fractured or collapsed vertebra

Investigations

Dual-energy X-ray absorptiometry (DEXA) scan: The gold standard for measuring bone mineral density (BMD) and diagnosing osteoporosis.
FRAX score: A tool to estimate the 10-year probability of a major osteoporotic fracture and guide treatment decisions.
Blood tests: To rule out secondary causes of osteoporosis, including calcium, phosphate, alkaline phosphatase, vitamin D, and thyroid function tests.
Vertebral imaging: To detect vertebral fractures if there is back pain or height loss.

Management

Primary Care Management

Lifestyle modifications: Encouraging a diet rich in calcium and vitamin D, regular weight-bearing and muscle-strengthening exercises, smoking cessation, and limiting alcohol intake.
Calcium and vitamin D supplementation: For individuals at risk of deficiency or with low dietary intake.
Medications:
- Bisphosphonates: (e.g., alendronate, risedronate) to reduce bone resorption.
- Selective oestrogen receptor modulators (SERMs): (e.g., raloxifene) to mimic oestrogen's bone-protective effects.
- Denosumab: A monoclonal antibody that inhibits osteoclast formation and function.
Monitoring: Regular follow-up to assess treatment adherence, side effects, and bone mineral density.
Education: Providing information on the importance of lifestyle changes, medication adherence, and fall prevention strategies.

Specialist Management

Referral to an endocrinologist or rheumatologist: For complex cases or if the patient has secondary osteoporosis.
Parathyroid hormone (PTH) analogues: (e.g., teriparatide) for severe osteoporosis not responding to other treatments.
Hormone replacement therapy (HRT): For postmenopausal women at high risk of fractures, considering the benefits and risks.
Management of fractures: Orthopaedic referral for fracture management, including surgical intervention if necessary.

Example Management for Osteoporosis

A postmenopausal woman diagnosed with osteoporosis presenting with a DEXA scan showing low bone mineral density should be managed with lifestyle modifications such as a diet rich in calcium and vitamin D, regular weight-bearing exercises, and smoking cessation. Pharmacological treatment may include bisphosphonates (e.g., alendronate) to reduce bone resorption. Regular monitoring of bone mineral density and serum calcium and vitamin D levels is essential to assess the effectiveness of treatment and detect potential side effects. The patient should be educated on the importance of medication adherence, fall prevention strategies, and maintaining a healthy lifestyle.

References

NICE. (2024). Osteoporosis: Assessing the Risk of Fragility Fracture. Retrieved from NICE
NHS. (2023). Osteoporosis. Retrieved from NHS
National Osteoporosis Foundation. (2022). Clinician’s Guide to Prevention and Treatment of Osteoporosis. Retrieved from National Osteoporosis Foundation
Royal Osteoporosis Society. (2021). Managing Osteoporosis and Preventing Fragility Fractures. Retrieved from Royal Osteoporosis Society