MKSAP quiz on orthopedic comanagement

Case 1: Thromboprophylaxis

A 49-year-old man is scheduled for total right knee arthroplasty. Medical history is otherwise unremarkable. He takes no medications.

On physical examination, vital signs are normal. The right knee demonstrates bony hypertrophy and crepitus with passive movement.

Low-molecular-weight heparin and intermittent pneumatic compression will be initiated and continued during the hospital stay.

Which of the following is the recommended duration of low-molecular-weight heparin prophylaxis for this patient?

A. Total of 10 days
B. Total of 14 days
C. Total of 35 days
D. Until fully ambulatory
E. Until hospital discharge

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Case 2: Bone health testing

A 57-year-old woman is evaluated during hospitalization following surgical fixation of a right femur neck pathologic fracture. Pathology of the femur shows a neoplasm containing numerous giant cells consistent with brown tumor.

On physical examination, vital signs are normal. There is a palpable mass on the lower left side of the right neck. There is an incision with surgical staples on the right hip. The remainder of the examination is unremarkable.

Laboratory studies show alkaline phosphatase 260 U/L, calcium 13.2 mg/dL (3.3 mmol/L), creatinine 1.6 mg/dL (141.4 µmol/L), phosphorus 1.9 mg/dL (0.6 mmol/L), and parathyroid hormone 1,142 pg/mL (1,142 ng/L). Neck ultrasound shows a solid hypervascular mass (6 × 2.9 × 3 cm) posterior to the left lobe of the thyroid, with compression and displacement of the trachea. A parathyroidectomy is planned.

Which of the following is the most appropriate test to perform next?

A. 1,25-Dihydroxyvitamin D level
B. 24-Hour urine calcium level
C. 25-Hydroxyvitamin D level
D. Ionized calcium level

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Case 3: Discharge prescribing

A 35-year-old woman is about to be discharged from the hospital. Several months ago she sustained pelvic and right femur fractures in a motor vehicle accident. She was recently discharged after a staged pelvic reconstruction surgery but was readmitted for pain management because her pain was not adequately controlled with oral oxycodone. She is now receiving a medication regimen that provides adequate pain relief. Medical history is also significant for obstructive sleep apnea. Current medications are acetaminophen, fentanyl patch (equivalent to 50 mg of morphine/day), and naproxen as needed.

Which of the following drugs should be included in the patient's discharge medications?

A. Buprenorphine
B. Flumazenil
C. Naloxone
D. Naltrexone

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Case 4: Diagnosis after a fall

A 78-year-old woman is evaluated in the emergency department for severe pain in the left hip after a fall. History is significant for end-stage kidney disease as of 18 months ago, hypertension, and peripheral vascular disease. Medications are lisinopril, amlodipine, sevelamer, and epoetin alfa. She is also receiving morphine for the hip pain.

On physical examination, blood pressure is 132/70 mm Hg, and pulse rate is 72/min; other vital signs are normal. The left lower extremity is externally rotated at the hip. Peripheral pulses are diminished. The remainder of the physical examination is noncontributory.

Laboratory studies show alkaline phosphatase 78 U/L, calcium 9.7 mg/dL (2.4 mmol/L), phosphorus 4.2 mg/dL (1.4 mmol/L), parathyroid hormone 62 pg/mL (62 ng/L), and 25-hydroxyvitamin D 32 ng/mL (80 nmol/L).

Radiographs of the hips show a left hip fracture and calcified arteries.

Which of the following is the most likely diagnosis for the underlying bone disease?

A. Adynamic bone disease
B. β2-Microglobulin–associated amyloidosis
C. Osteitis fibrosis cystica
D. Osteomalacia

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Case 5: Infection prevention

A 39-year-old man is evaluated in the hospital after a motorcycle accident that necessitated an open reduction and internal fixation of a femur fracture. During the emergency department evaluation, an indwelling urinary catheter was placed. Medical history is noncontributory, and he takes no medications.

On physical examination, he is alert and oriented. Vital signs are normal. The left leg is tender, with a sterile dressing over the incision.

Which of the following is the most appropriate urinary catheter management?

A. Change catheter to an antimicrobial or antiseptic-coated catheter
B. Initiate prophylactic antibiotics
C. Maintain catheter placement until patient is ambulatory
D. Remove catheter and observe for spontaneous voiding

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Answers and commentary

Case 1

Correct answer: C. Total of 35 days.

The recommended postoperative duration of venous thromboembolism (VTE) prophylaxis with low-molecular-weight heparin (LMWH) following major orthopedic surgery is 35 days in patients who are not at increased bleeding risk and have not experienced perioperative bleeding complications. The American College of Chest Physicians (ACCP) antithrombotic guideline provides recommendations for VTE prophylaxis for both orthopedic and nonorthopedic surgery populations. The ACCP guideline identifies hip arthroplasty, knee arthroplasty, and hip fracture surgery as major orthopedic surgeries. These surgeries pose a high VTE risk, and both pharmacologic and mechanical VTE prophylaxis are recommended during hospitalization. The ACCP recommends LMWH over other pharmacologic agents, although there are other acceptable agents, including aspirin for those unable or unwilling to take heparin. For patients without increased bleeding risk, extended duration of postoperative prophylaxis for up to 35 days is recommended over shorter-duration prophylaxis of 10 to 14 days, which is the minimum recommended duration of pharmacologic VTE prophylaxis in orthopedic surgery. Randomized trials, systematic reviews, and meta-analyses have shown that compared with placebo, aspirin, and warfarin, extended prophylaxis up to 35 days with LMWH reduces the rate of VTE disease without excess bleeding in patients who undergo major orthopedic surgery. If bleeding risk is especially high, mechanical prophylaxis is recommended over no prophylaxis. In patients who decline LMWH injections or who are unable to tolerate LMWH, the oral direct thrombin inhibitor dabigatran, a factor Xa inhibitor (apixaban, rivaroxaban, edoxaban), or a vitamin K antagonist (warfarin) is recommended over alternate forms of prophylaxis. For this patient undergoing major orthopedic surgery, dual perioperative VTE prophylaxis with LMWH and intermittent pneumatic compression is recommended during hospitalization, with LMWH continued for up to 35 days.

Because of the elevated risk for VTE in many patients undergoing orthopedic surgery, a short course of VTE prophylaxis, such as 10 or 14 days, is insufficient because thrombotic risk remains elevated beyond this time frame.

Key Point

  • For patients undergoing orthopedic surgery without increased bleeding risk, postoperative dual venous thromboembolism prophylaxis with intermittent pneumatic compression and low-molecular-weight heparin is recommended during hospitalization; low-molecular-weight heparin should be continued for up to 35 days.

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Case 2

Correct answer: C. 25-Hydroxyvitamin D level.

The most appropriate test to perform next for this patient is measurement of her 25-hydroxyvitamin D level. Vitamin D deficiency is common in patients with primary hyperparathyroidism (HPT) due to increased conversion of 25-hydroxyvitamin D to 1,25-dihydroxyvitamin D. Supplementation of vitamin D in patients with HPT has been shown to reduce parathyroid hormone levels, decrease bone turnover, and improve bone mineral density. Identifying and treating vitamin D deficiency perioperatively helps manage transient hypocalcemia, which routinely occurs after parathyroidectomy and especially in severe HPT where high bone turnover (as evidence by an elevated alkaline phosphatase) portends hungry bone syndrome.

Due to increased conversion, 1,25-dihydroxyvitamin D levels are frankly elevated in most instances of hyperparathyroidism and even in patients who are vitamin D deficient. It is not a useful test to identify and manage vitamin D deficiency in any circumstance and could be falsely reassuring in patients with HPT.

Given kidney excretion of calcium is the dominant mechanism by which hypercalcemia is corrected, urine calcium excretion can be assumed to be high in severe hypercalcemia with the exception of patients with severe acute kidney injury. Although guidelines suggest routine assessment of 24-hour urine calcium in the evaluation of HPT to exclude familial hypocalciuric hypercalcemia, the need for such screening primarily occurs when parathyroid hormone and calcium levels are mildly elevated. Additionally, a clinical diagnosis has already been established for this patient making 24-hour urine calcium measurement unnecessary.

Ionized calcium is the best test to assess the state of calcium homeostasis and is recommended by some experts when managing HPT. However, it is primarily of use when evaluating and managing hypocalcemia, especially when assumptions cannot be made regarding serum protein concentrations and blood pH.

Key Point

  • In patients with primary hyperparathyroidism who are undergoing parathyroidectomy surgery, identifying and correcting vitamin D deficiency is important to avoid postoperative hypocalcemia, which occurs due to rapid flux of serum calcium into bone (hungry bone syndrome).

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Case 3

Correct answer: C. Naloxone.

For this patient, naloxone should be included as part of her discharge medications. Over the past decade, the number of opioid-related deaths in the United States has increased substantially. Easy-to-administer intranasal or injectable naloxone has been shown to reduce the risk for opioid-related overdose when provided to first responders. Emerging evidence demonstrates benefits when prescribed as a preventative measure in the office setting as well. An opiate blocker, naloxone acts within minutes, making it the best choice in an emergency overdose situation. According to the Centers for Disease Control and Prevention opioid prescribing guideline, clinicians should offer naloxone to any patient at risk for opioid overdose. This includes patients with a history of overdose or substance use disorder, as well as patients taking benzodiazepines with opioids (which should be avoided whenever possible), and/or taking more than 50 morphine milligram equivalents per day. Caution should also be taken in patients who have risk factors for opioid-related harms, such as the elderly; patients with mental health conditions; and patients at risk for sleep-disordered breathing, such as those with heart failure, obstructive sleep apnea, or obesity. This patient uses high-dose opioids and has obstructive sleep apnea. She should be prescribed naloxone, and she and a housemate should be educated on its proper use.

Buprenorphine is used to treat opioid addiction by reducing cravings in patients with opioid use disorder. There is no evidence of opioid use disorder in this patient.

Flumazenil is a γ-aminobutyric acid (GABA)–receptor antagonist used for benzodiazepine overdose, not opioid overdose. However, its use in benzodiazepine overdose remains controversial because of its short half-life and ability to precipitate withdrawal seizures in patients with long-term benzodiazepine use.

Naltrexone is a long-term opioid blocker that takes effect in 1 to 2 hours. It is used to prevent relapse in patients with opioid and alcohol use disorders, which are not evident in this patient.

Key Point

  • Clinicians should offer naloxone to any patient with a history of overdose or substance use disorder, as well as patients taking benzodiazepines with opioids, or more than 50 morphine milligram equivalents per day; added caution is also needed for older patients, patients with mental health disorders, and patients at risk for sleep-disordered breathing.

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Case 4

Correct answer: A. Adynamic bone disease.

The most likely bone pathology is adynamic bone disease in this patient with end-stage kidney disease and normal serum calcium and phosphorus and relatively suppressed parathyroid hormone (PTH) and alkaline phosphatase levels. Adynamic bone disease can occur in patients with chronic kidney disease (CKD) or those on dialysis. It is typically associated with significant vascular calcifications. The gold standard for the diagnosis of adynamic bone disease is bone biopsy; however, this is rarely performed. Adynamic bone disease has no specific markers, but a constellation of findings may suggest this diagnosis. Patients with adynamic bone disease may present with fracture or bone pain. The latter has been attributed to the inability to repair microdamage because of low turnover. Serum calcium may be normal or elevated because the bone is unable to take up calcium. High PTH and alkaline phosphatase would exclude adynamic bone disease; in this disorder, both are typically normal. Treatment is targeted at factors that allow PTH secretion to rise. This includes avoiding calcium-based binders, conservative use of vitamin D, and decreasing the dialysate calcium concentration. It is important to note that, as with the general population, patients with CKD may also develop osteoporosis, particularly if they received glucocorticoid therapy for the primary kidney disorder or for immunosuppression in the setting of a kidney transplant.

β2-Microglobulin–associated amyloidosis is usually seen in patients who have been on dialysis for at least 5 years. This disorder involves osteoarticular sites, and patients may present with carpal tunnel syndrome or shoulder pain. Bone cysts may be visible on radiograph.

Osteitis fibrosa cystica is the classic pathology associated with kidney disease. This disorder is associated with increased bone turnover and elevated PTH and alkaline phosphatase levels. Mixed uremic osteodystrophy has elements of both high and low bone turnover.

Osteomalacia refers to a defect with both low turnover and abnormal mineralization of bone. This disorder can be seen by vitamin D deficiency, but in the past, it was a common complication of aluminum toxicity. This patient's vitamin D level is in the “sufficient range,” and there is no history of aluminum exposure.

Key Point

  • Adynamic bone disease can occur in patients with chronic kidney disease or those on dialysis and is associated with fracture or bone pain; parathyroid hormone and alkaline phosphatase levels are typically normal.

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Case 5

Correct answer: D. Remove catheter and observe for spontaneous voiding.

The proper management of the patient's urinary catheter is to remove it and observe the patient for spontaneous voiding. Catheters should be used for appropriate indications only, which include urinary retention and bladder outlet obstruction, measurement of urinary output in critically ill patients, perioperative use for selected surgical procedures, assistance with healing of perineal or sacral wounds in patients with incontinence, use in patients requiring prolonged immobilization, and contribution to comfort at the end of life. An indwelling urinary catheter is sometimes inserted in the emergency department during trauma evaluation; however, the need for continuing the catheter should be assessed when the initial evaluation has been completed. If this patient required prolonged immobilization (for example, multiple traumatic injuries such as pelvic fractures), continuing the indwelling urinary catheter may be appropriate. Patients should be monitored closely for their ability to void spontaneously when a catheter is removed. Bladder ultrasonography can be used to determine residual postvoid volume; if more than 200 mL remain, consider intermittent catheterization for a short amount of time rather than placing a new indwelling urinary catheter. Early removal of urinary catheters should be considered when possible and can be encouraged by reminder systems. Additionally, nurse-initiated removal protocols have been shown to be effective in limiting duration of catheterization. Catheter-associated urinary tract infection (CAUTI) prevention strategies are summarized by the acronym ABCDE: Adhere to general infection control principles, perform Bladder ultrasonography to potentially avoid catheterization, use Condom catheters or intermittent catheterization when appropriate, Do not use an indwelling catheter if criteria for use are not met, and remove catheters Early when they are no longer indicated using computerized reminders or nurse-driven removal protocols.

Antimicrobial-impregnated or antiseptic-coated catheters have not been shown to decrease CAUTIs with short-term (<14 days) catheterization. Information is scarce on their benefits with long-term urinary catheters. Early removal of the catheter is a better care strategy.

Administering antibiotics with the goal of preventing infection is not effective and promotes antibiotic-resistant bacteria and fungal CAUTIs and is not indicated in this case.

Key Point

  • Early removal of urinary catheters should be considered when possible, and patients should be monitored for their ability to void spontaneously after catheter removal.