Introduction
Osteoporosis is a systemic skeletal disorder characterized by decreased bone mass and microarchitectural deterioration of bone tissue, leading to increased bone fragility and susceptibility to fractures. It is often asymptomatic until a fracture occurs, earning it the moniker “the silent disease.” As life expectancy rises, the global burden of osteoporosis-related fractures is projected to increase, underscoring the need for comprehensive prevention, early detection, and effective management strategies.
Epidemiology and Impact
- Prevalence: Osteoporosis affects more than 200 million people worldwide. In the United States, approximately 10 million individuals have the disease, and another 44 million have low bone mass (osteopenia).
- Fracture Risk: Lifetime risk of sustaining an osteoporotic fracture is ~30–40% for women and 15–20% for men. Hip fractures, in particular, carry a 1-year mortality of nearly 20%.
- Economic Burden: Annual direct costs for osteoporotic fractures exceed $20 billion in the U.S. and €37 billion in Europe, driven largely by hip fracture hospitalizations and long-term care.
Pathophysiology
Bone remodeling is a dynamic balance between osteoclast-mediated resorption and osteoblast-driven formation. In osteoporosis, factors such as estrogen deficiency, chronic glucocorticoid exposure, vitamin D insufficiency, and aging tilt this balance toward excessive resorption. The resulting microarchitectural changes include thinning of trabecular bridges, cortical porosity, and loss of structural connectivity, all of which compromise bone strength.
Risk Factors
Non-modifiable
– Age ≥65 years
– Female sex, particularly postmenopausal
– Family history of hip or vertebral fracture
– Ethnicity: Caucasian and Asian backgrounds
Modifiable
– Low body mass index (<20 kg/m²)
– Smoking tobacco
– Excessive alcohol intake (>3 units/day)
– Sedentary lifestyle
– Inadequate calcium and vitamin D intake
– Chronic use of glucocorticoids, aromatase inhibitors, or anticonvulsants
Clinical Presentation
Osteoporosis is classically silent until presenting with a fragility fracture. Common fracture sites and presentations include:
1. Vertebral Compression Fractures: Acute or insidious back pain, height loss (>2 cm), kyphosis, and reduced pulmonary function.
2. Hip Fractures: Severe pain in the hip or groin, inability to bear weight, and often require surgical intervention.
3. Distal Radius (Colles’) Fractures: Pain and deformity of the wrist after minimal trauma, often heralding systemic bone fragility.
Diagnostic Evaluation
- Bone Mineral Density (BMD): Dual-energy X-ray absorptiometry (DXA) at the lumbar spine and hip remains the gold standard. A T-score ≤ –2.5 indicates osteoporosis; –1.0 to –2.5 indicates osteopenia.
- Vertebral Imaging: Lateral spine radiographs or vertebral fracture assessment (VFA) for patients with chronic back pain or height loss.
- Laboratory Testing: Serum calcium, 25-hydroxyvitamin D, renal and liver function, thyroid-stimulating hormone, and markers of bone turnover (e.g., CTX, P1NP) to exclude secondary causes and guide therapy.
- Risk Assessment Tools: FRAX® algorithm estimates 10-year probability of hip and major osteoporotic fractures, integrating clinical risk factors with or without BMD.
Prevention Strategies
Primary prevention aims to optimize peak bone mass and minimize subsequent bone loss. Key interventions include:
– Nutrition: Ensure daily calcium intake of 1,000–1,200 mg through diet (dairy, leafy greens, fortified foods) and 800–1,000 IU of vitamin D via supplementation or sun exposure. Encourage foods rich in vitamin K (e.g., green vegetables) to support bone matrix formation.
– Physical Activity: Recommend weight-bearing and muscle-strengthening exercises, such as brisk walking, stair climbing, resistance training, and balance exercises. Aim for at least 150 minutes of moderate-intensity activity per week.
– Lifestyle Modification: Advise smoking cessation and limit alcohol to ≤2 standard drinks per day. Counsel patients on fall prevention strategies, including home hazard assessment, vision correction, balance training, and appropriate footwear.
– Pharmacologic Prophylaxis: In high-risk individuals (e.g., prolonged glucocorticoid therapy), consider early initiation of antiresorptive agents such as bisphosphonates or denosumab to prevent rapid bone loss.
Management of Established Osteoporosis
Non-Pharmacologic
– Continued emphasis on nutrition, exercise, and fall prevention.
– Physical therapy to improve postural alignment and muscle strength.
Pharmacologic Interventions
1. Bisphosphonates: First-line therapy (e.g., alendronate 70 mg weekly, risedronate 35 mg weekly); inhibit osteoclast activity and reduce fracture risk by 40–50%.
2. Denosumab: 60 mg subcutaneous injection every 6 months; monoclonal antibody against RANKL, indicated for patients intolerant to bisphosphonates or with impaired renal function.
3. Selective Estrogen Receptor Modulators: Raloxifene 60 mg daily; reduces vertebral fractures and offers additional benefits on lipid profile.
4. Anabolic Agents: Teriparatide 20 µg daily subcutaneously for up to 24 months; stimulates osteoblast function and improves bone microarchitecture.
5. Hormone Replacement Therapy: Consider in younger postmenopausal women with significant vasomotor symptoms and low cardiovascular risk.
Monitoring and Follow-Up
- Re-evaluate BMD by DXA every 1–2 years, depending on treatment and fracture risk.
- Monitor adherence to therapy, dietary intake, and adverse effects (e.g., gastrointestinal symptoms with bisphosphonates, hypocalcemia with denosumab).
- Assess fall risk annually and reinforce preventative measures.
- Consider “drug holidays” after 3–5 years of bisphosphonate therapy in low-risk patients to minimize rare complications.
Patient Education
- Explain the chronic nature of osteoporosis and the importance of long-term adherence to therapy.
- Discuss potential side effects and strategies to mitigate them (e.g., taking bisphosphonates with water on an empty stomach, remaining upright for 30 minutes).
- Encourage active participation in lifestyle changes and regular follow-up.
Conclusion
Osteoporosis is an underdiagnosed and undertreated condition with significant implications for morbidity and healthcare costs. Comprehensive strategies encompassing risk assessment, preventive measures, timely diagnosis, and targeted therapeutic interventions are essential to reduce fracture incidence, preserve function, and enhance quality of life in at-risk populations.
