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What You Should Know about Bone Disorders for the Physician Assistant Exam

In your practice and for the Physician Assistant Exam you’ll likely deal with the bones a lot. You should know about three big bone disorders, namely osteoporosis, osteoarthritis, and osteomyelitis.

Bone thinning: Osteoporosis

Osteoporosis, which is a loss of bone density, occurs most commonly in women after menopause. Risk factors for developing osteoporosis include age, hormonal status (post-menopause), lifestyle (exercise and muscle resistance training decrease osteoporosis risk), and alcohol and tobacco use.

The gold standard for the detection of osteoporosis is the DEXA scan. The DEXA scan is scored on the basis of a T-score, which compares a patient’s bone density to the peak bone density of 30-year-old women.

Treatment for osteoporosis involves stopping smoking and drinking, increasing calcium and vitamin D intake, and increasing physical activity, especially muscle-strengthening exercises such as weight training. Prescription medications for treating osteoporosis include the bisphosphonates, such as alendronate (Fosamax) and ibandronate.

For PANCE purposes, be aware of possible side effects of the bisphosphonates, including jaw necrosis and esophageal irritation. Avoid giving the patient bisphosphonates if advanced kidney disease (GFR < 30 mL/min) is present. In place of these medications, you may use calcitonin nasal spray.

Anti-estrogen therapy such as raloxifene is also prescribed for osteoporosis. Common side effects are hot flashes, leg cramps, and blood clots in the legs, lungs, or eyes. Other reactions can include leg swelling/pain, trouble breathing, chest pain, or vision changes.

Osteoarthritis

Osteoarthritis (OA) is the most common cause of degenerative arthritis in the United States. It’s characterized by “bone being on bone.” Think of the joint cartilage as being the buffer or padding between two articular surfaces, like the meat in a sandwich. Lose the cartilage, and you develop a bad arthritis that can involve the back, hip, knees, and other weight-bearing joints.

The more the person weighs, the worse osteoarthritis can get. Osteoarthritis can be debilitating and can affect quality of life.

With osteoarthritis, radiologic studies show narrowing of the joint space and formation of osteophytes.

Treatment for osteoarthritis includes weight loss and pain relief. The first-line analgesics are acetaminophen and nonsteroidals such as ibuprofen. If this doesn’t work, second-line therapy can involve the non-narcotic analgesic tramadol. This med is an opioid but not a controlled substance. Glucosamine and chondroitin sulfate as well as methylsulfonylmethane have been used in treating osteoarthritis.

Weight can worsen osteoarthritis, so exercise, weight loss, and physical therapy are important in regaining mobility and ambulation.

Bad to the bone: Osteomyelitis

During your hospital rotations, you may have seen someone with a history of diabetes who was admitted for evaluation of a worsening foot ulcer. The million-dollar question is always “Has the infection spread to the bone?” That is, is an osteomyelitis present? And if an osteomyelitis is present, is it occurring acutely, or has it being going on for a while?

The diabetic foot ulcer is a common etiology of osteomyelitis. Vascular disease and diabetes are typically associated with osteomyelitis. An osteomyelitis can also occur in the sacrum. What starts out as a soft tissue infection can transform into an osteomyelitis. If you’re asked about possible organisms on a diabetic foot ulcer, think about Staphylococcus aureus among Gram-positive organisms and Pseudomonas aeruginosa among Gram-negatives.

Common clinical presentations of osteomyelitis include fever, rigors, and erythema and tenderness around the area. If an open wound is present, it can be weeping. Use a cotton swab on examination to see whether the wound goes down to the bone. Obtain a wound culture, but note that if it’s not done the right way, you may just end up with normal skin flora and a subsequent false negative result.

The MRI is the test of choice for diagnosing an osteomyelitis. The MRI is better than a bone scan, which can pick up many bony abnormalities but may not be specific. However, if an MRI isn’t possible, the bone scan is the next best test.

Treat osteomyelitis with intravenous antibiotics. They’re often given for an average of 6 weeks, although the duration can change, based on the nature of the organism. Periodically check labs that test for inflammation, including the sed rate or C-reactive protein (CRP). In clinical practice, infectious-disease healthcare providers, who are often consulted initially for help in management, follow these patients.

With osteomyelitis, anything that can be done to improve vascular flow, especially to the lower extremities, is key, especially because antimicrobial therapy doesn’t work as effectively if the blood flow to the area is compromised.

You’re evaluating a 50-year-old man with a history of drug use who presents with fevers and rigors. Blood cultures are positive for Staphylococcus aureus. You obtain a transesophageal echocardiogram (TEE), and there’s no evidence of valvular vegetation. In addition to starting antibiotics, which of the following would be your next step?

(A) Repeat blood cultures.
(B) Examine the body for possible injection sites.
(C) Examine the sacrum for a possible decubitus.
(D) Check a urine culture and sensitivity.
(E) Obtain an MRI of the spine.

The answer is Choice (E). Staphylococcus aureus is a bad bacterium. If someone is presenting with blood cultures positive for this organism, especially with a history of drug abuse, you need to think about two body areas that can be affected: the heart and the bones.

Staph aureus can cause valvular vegetations, and in someone with a history of intravenous drug abuse, it can cause right-sided endocarditis. Staph aureus can also cause an osteomyelitis. In this question, you’re looking for a possible source. The TEE is negative, so you need to check out the spine, Choice (E).

Staph aureus is a true bacterium, so never treat it as a blood contaminant, Choice (A). This patient has no risk factors for a sacral decubitus, Choice (C) — he isn’t nonambulatory or bed bound. Concerning Choice (D), patients who have indwelling Foley catheters are at higher risk for urinary colonization with Staph. They are not treated if they’re asymptomatic.

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