Dr. Kevin Yip

Dr Kevin Yip
Orthopaedic Surgeon
MBBS(UK), FRCS(EDIN), FAM(SING), FHKCOS(ORTHO)

Featured on Channel NewsAsia

Osteoporosis

Basics
Description
  • Osteoporosis is characterized by low bone mass and microarchitectural deterioration of bone tissue, leading to enhanced bone fragility and an increase in fracture risk.
  • The World Health Organization defines osteoporosis as a bone mineral density score 2.5 standard deviations less than the mean value for a young person of the same gender .
General Prevention
Prevention of bone loss in asymptomatic females is achieved through behavior modification, including alterations in nutrition and lifestyle.
 
Epidemiology
  • Osteoporosis is responsible for 1.3 million fractures yearly: 1/2 are vertebral fractures, 1/4 are hip fractures, and 1/4 are wrist fractures .
  • The fracture rate increases with age, especially after age 75 .
  • After age 50, females are 3 times more likely than males to sustain a fragility fracture (40% versus 13%, respectively) .
Risk Factors
  • Caucasian (Northern European descent) and Asian ethnicity
  • Female gender
  • Late menarche, nulliparity, early menopause, excessive exercise (producing amenorrhea)
  • Increasing age
  • Positive family history
  • Small body frame (<127 lb)
Genetics
The genetic component of this disease is not known.
 
Etiology
  • Idiopathic secondary
  • Nutritional: Milk intolerance, vegetarian dieting, low dietary calcium, excessive alcohol intake
  • Lifestyle: Smoking, inactivity
  • Medical: Type I diabetes, Cushing syndrome, chronic renal disease, inflammatory bowel disease, cystic fibrosis, hyperparathyroidism, hyperthyroidism, anorexia nervosa, celiac disease, idiopathic hypercalciuria, premature ovarian failure
  • Medications: Glucocorticoid drugs, long-term lithium therapy, chemotherapy, anticonvulsants (phenytoin, phenobarbital, valproate, and carbamazepine), long-term phosphate-binding antacid use, thyroid replacement drugs, methotrexate, FK-506
Diagnosis
Signs and Symptoms
History
High suspicion of osteoporosis in any patient with a fracture caused by minimal trauma

Physical Exam
Vertebral fractures are associated with loss of stature caused by a progressive increase in the degree of kyphosis and lordotic curve flattening.
 
Tests
  • DEXA:
    • Measures bone density at the femoral neck, spine, and distal radius
    • Results are related as T scores: The number of standard deviations the bone mineral density measurement is above or below the young normal mean bone mineral density.
Lab
  • A comprehensive metabolic panel, complete blood count, and thyroid stimulating hormone level
  • A normal calcium, thyroid stimulating hormone, and creatinine rule out hyperparathyroidism, hyperthyroidism, and chronic renal disease.
  • Normal blood count, a normal serum protein, and normal calcium virtually exclude multiple myeloma.
  • Serum 25-hydroxyvitamin D and parathyroid hormone if the patient is elderly or if a history of renal disease, gastrointestinal malabsorption, liver disease, or anticonvulsant drug therapy is present
Imaging
  • Radiography:
    • Plain radiographs are unremarkable until bone loss has reached 30%.
    • Moderate osteoporosis of the thoracic and lumbar spine causes signs of overall loss of bone density (osteopenia).
    • Widening of the medullary canal with thinning of the cortices can be seen in long bones.
  • Fractures may not be seen on initial radiographs, and may require bone scintigraphy, CT, MRI, or repeat plain radiographs.
Pathological Findings
  • Excessive bone loss results from abnormalities in the bone remodeling cycle.
  • The cycle involves resorption of old bone by osteoclasts, recruitment of osteoblasts to deposit new matrix, and mineralization of that newly deposited matrix.
  • In osteoporosis, a loss of a small amount of bone mass occurs with each cycle.
  • Hyperparathyroidism increases the rate of activation of bone remodeling.
Differential Diagnosis
  • Osteomalacia
  • Neoplasm (myeloma, leukemia)
  • Paget disease of the bone
  • OI
Treatment
General Measures
Activity
Weightbearing exercise regimens cause modest increases in bone mineral density.

Medication
First Line
  • Calcium supplements: 1,200 mg per day.
  • Vitamin D: 800 IU per day.
  • Diphosphonates:
    • Cause decreased osteoclast activity.
    • Decreases fracture rate at hip, spine, and wrist by 50%
    • Patients require calcium and vitamin D for maximal benefit.
    • Weekly (alendronate, risedronate) and monthly dosing (ibandronate) is available .
Second Line
  • Selective estrogen receptor modulators:
    • Reduce the vertebral fracture rate by 50%, but have no effect on the hip fracture rate
    • Raloxifene is the only FDA-approved selective estrogen receptor modulator for treating osteoporosis.
  • Estrogen replacement reduces the risk of fracture but is associated with an increase in cardiovascular and thromboembolic events .
  • Calcitonin:
    • Inhibits bone resorption by acting on osteoclasts
    • Its ability to reduce fracture rates has been questioned .
  • Recombinant parathyroid hormone:
    • Results in stimulation of new bone formation
    • It is expensive and should be prescribed only by specialists .
Surgery
  • Surgical treatment is related to the management of impending or completed fractures.
  • Vertebroplasty and kyphoplasty, procedures in which methacrylate bone cement is injected percutaneously into osteoporotic vertebrae that have collapsed, show promise but await long-term study.
Follow-up
Disposition
Issues for Referral
Patients with severe osteoporosis (T-score <3) should be referred to an endocrinologist to evaluate for secondary causes of osteoporosis.
 
Prognosis
The earlier therapy is instituted, the better the prognosis.
 
Complications
Fractures may occur.
 
Miscellaneous
Codes
ICD9-CM
  • 733.0 Generalized osteoporosis
  • 733.01 Senile osteoporosis/postmenopausal osteoporosis
  • 733.7 Posttraumatic osteoporosis
Patient Teaching
Activity
Exercise programs should focus on compliance through recreational therapy.

Prevention
Patients should take the daily recommended amounts of calcium and vitamin D and perform daily exercise.
 
FAQ
Q: What is the correct way to take a diphosphonate?
A: After getting up for the day and before taking food, beverage, or other medication, the individual should swallow the tablet whole with a full glass of plain water. Stay fully upright for at least 30 minutes and do not lie down until after the 1st food of the day. Wait at least 30 minutes before you eat or drink anything other than plain water.
 
Q: How soon after starting treatment of osteoporosis should you check a DEXA scan?
A: A DEXA scan will not show substantial changes in bone mineral density any sooner than 1 year after the initiation of therapy.

Comments are closed.