Osteoporosis

By admin On Feb 17, 2024

Ovid: 5-Minute Orthopaedic Consult

Editors: Frassica, Frank J.; Sponseller, Paul D.; Wilckens, John H.

Title: 5-Minute Orthopaedic Consult, 2nd Edition

> Table of Contents > Osteoporosis

Osteoporosis

Anirudh Sridharan MD

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 (1).

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 (2).
The fracture rate increases with age, especially after age 75 (2).
After age 50, females are 3 times more likely than males to sustain a fragility fracture (40% versus 13%, respectively) (2).

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% (3)
- Patients require calcium and vitamin D for maximal benefit.
- Weekly (alendronate, risedronate) and monthly dosing (ibandronate) is available (4).

Second Line

Selective estrogen receptor modulators:
- Reduce the vertebral fracture rate by 50%, but have no effect on the hip fracture rate (5)
- 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 (6).
Calcitonin:
- Inhibits bone resorption by acting on osteoclasts
- Its ability to reduce fracture rates has been questioned (7).
Recombinant parathyroid hormone:
- Results in stimulation of new bone formation
- It is expensive and should be prescribed only by specialists (8).

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.

P.301

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.

References

1. Kanis
JA, WHO Study Group. Assessment of fracture risk and its application to
screening for postmenopausal osteoporosis: synopsis of a WHO report. Osteoporos Int 1994;4:368–381.

2. US
Department of Health and Human Services. Bone Health and Osteoporosis:
A Report of the Surgeon General. Rockville, MD: U.S. Department of
Health and Human Services, Office of the Surgeon General, 2004.

3. Papapoulos
SE, Quandt SA, Liberman UA, et al. Meta-analysis of the efficacy of
alendronate for the prevention of hip fractures in postmenopausal
women. Osteoporos Int 2005;16:468–474.

4. Fleisch H. Development of bisphosphonates. Breast Cancer Res 2002;4:30–34.

5. Ettinger
B, Black DM, Mitlak BH, et al. Reduction of vertebral fracture risk in
postmenopausal women with osteoporosis treated with raloxifene: results
from a 3-year randomized clinical trial. JAMA 1999;282:637–645.

6. Rossouw
JE, Anderson GL, Prentice RL, et al. Risks and benefits of estrogen
plus progestin in healthy postmenopausal women: principal results from
the Women’s Health Initiative randomized controlled trial. JAMA 2002;288:321–333.

7. Chesnut
CH, III, Silverman S, Andriano K, et al. A randomized trial of nasal
spray salmon calcitonin in postmenopausal women with established
osteoporosis: the prevent recurrence of osteoporotic fractures study. Am J Med 2000;109: 267–276.

8. Rosen CJ, Rackoff PJ. Emerging anabolic treatments for osteoporosis. Rheum Dis Clin North Am 2001;27:215–233.

Additional Reading

Favus MJ, ed. Primer on the Metabolic Bone Diseases and Disorders of Mineral Metabolism, 5th ed. Washington, DC: American Society for Bone and Mineral Research, 2003.

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.