Metabolic and endocrine bone disorders Osteoporosis
Introduction Patients with metabolic bone disorders usually appear to the orthopaedic surgeon in one of the following guises: • A child with bone deformities (rickets) • An elderly with a fracture of femoral neck or vertebral body • An elderly patient with bone pain and multiple compression fractures • A middle-aged person with hypercalcaemia and pseudogout • Someone with multiple fractures and history of prolonged corticosteroid treatment
X-ray features Stress fractures Vertebral fractures, Cortical thinning Loss of trabecular structure Ill-defined loss of radiographic density
History Failure to thrive Below-normal growth Deformity of the lower limbs Back pain Generalized muscle weakness
Cont’d Patient’s sex and age Race Onset of menopause Nutritional background Level of physical activity Previous illnesses medication and operations Onset and duration of symptoms and their relationship to previous disease
Examination Moon face Cushingoid build Smooth, hairless skin of testicular atrophy Physical underdevelopment and bone deformities. Thoracic kyphosis
X-rays Decreased skeletal radiodensity Reduction in mineral or skeletal mass Presence of obvious fractures Small stress fractures
Measurement of bone mass Dual-energy X-ray absorptiometry (DXA) scan
Indications for bone densitometry Adults over the age of 50 who have experienced a low trauma fracture All women over the age of 65 All men over the age of 75 To assess risk of future fracture To assess the degree and progress of bone loss To monitor the effect of treatment for osteoporosis.
Biochemical tests Serum calcium and phosphate concentrations should be measured in the fasting state Raised in osteomalacia and in disorders associated with high bone turnover
Bone biopsy Are obtained from the iliac crest Examined for histological bone volume, osteoid formation and relative distribution of formation and resorption surfaces
Osteoporosis
Definition Abnormally low bone mass Defects in bone structure, a combination which renders the bone unusually fragile
Cause Predominant bone resorption, decreased bone formation or a combination of the two
Risk factors for osteoporosis Age Female Previous fragility fracture Current use or frequent recent use of oral or systemic glucocorticoids Family history of hip fracture Low body mass index (BMI) (less than 18.5 kg/m2) Smoking Alcohol intake of more than 14 units per week for women and more than 21 units per week for men
X-rays Loss of trabecular definition, Thinning of the cortices Insufficiency fractures. Compression fractures of the vertebral bodies
Postmenopausal Osteoporosis It is an exaggerated form of the physiological bone depletion that normally accompanies ageing and loss of gonadal activity
Clinical features and investigations Osteoporosis is asymptomatic unless fractures occur. The fractures are classically low trauma Fracture of the distal radius ( Colles ’ fracture) is usually the first fracture Osteoporotic vertebral fractures Significant height loss (often exceeding 4 cm) and thoracic kyphosis Height loss and smaller kyphoses are most commonly due to degenerative change.
Cont’d Assessment of fracture risk The rate of bone turnover is either normal or slightly increased
Prevention Medications to reduce fracture risk. Primary screening for people who have not sustained Women should be advised on lifestyle choices to maintain healthy bones.
Treatment The goal is to reduce risk of future fracture. Medications recommended for 3–5 years, after which ongoing treatment should be reconsidered Bisphosphonates; taken orally Zoledronate can be given once per year intravenously. Denosumab subcutaneously injected every 6 months Parathyroid hormone Preotact and Teriparatide Selective oestrogen receptor modulators (SERMs)
Cont’d Strontium salt of ranelic acid, given as a sachet of granules to be dissolved in water and drunk once per day. Operative treatment. Analgesic treatment. Physiotherapy Postural training when symptoms allow. Spinal orthoses maybe needed for support and pain relief Vertebral augmentation such as kyphoplasty or vertebroplasty
Secondary causes of Osteoporosis Endocrine; Hypogonadism in either sex Treatment with aromatase inhibitors or androgen deprivation therapy Hyperthyroidism Hyperparathyroidism Hyperprolactinaemia Cushing’s disease and Diabetes
Cont’d Respiratory; Cystic fibrosis and Smoking-related lung disease Metabolic; Homocystinuria Chronic renal disease Gastrointestinal; Coeliac disease, Inflammatory bowel disease, Chronic liver disease Rheumatological; Rheumatoid arthritis and Other inflammatory arthropathies Haematological ; Multiple myeloma, Haemoglobinopathies and Systemic mastocytosis Immobility; Neurological injury and Neurological disease