Free PA-COS Practice Questions

Question 1

A 38-year-old sustains a closed midshaft humeral fracture in a low-energy fall. Before reduction, he cannot extend his wrist or fingers and has reduced sensation in the dorsal first web space. Alignment after reduction is acceptable, the hand is well perfused, and the neurologic findings are unchanged. During initial nonoperative fracture care, how should the nerve deficit be managed?

Accepted Answer

Provide a wrist-extension splint and monitor motor and sensory recovery serially.

Answer

Explore the radial nerve within 24 hours because both motor and sensory function are affected.

Answer

Obtain immediate electrodiagnostic testing to determine whether the nerve requires repair.

Answer

Postpone hand therapy until fracture union to avoid traction on the injured nerve.

Question 2

Seven hours after a tibial shaft fracture, a patient's pain continues to increase despite analgesia and complete release of the splint and padding. The anterior compartment is tense, and passive toe flexion causes marked pain. Blood pressure is 106/58 mm Hg; anterior compartment pressure is 40 mm Hg. Pedal pulses remain palpable. Which interpretation and action fit these findings?

Accepted Answer

The pressure difference is 18 mm Hg; proceed to immediate fasciotomy.

Answer

The pressure difference is 66 mm Hg; continue observation with serial examinations.

Answer

The pressure difference is 34 mm Hg; increase analgesia and repeat measurements later.

Answer

Preserved pedal pulses permit delaying decompression until a sensory deficit develops.

Question 3

At a revision-arthroplasty consultation, a 69-year-old reports six months of increasing pain and recurrent swelling in a knee replaced three years earlier. He had functioned well until these symptoms began. He is afebrile, has no inflammatory arthritis, and has received no recent antibiotics. There is a new tibial-component radiolucency. ESR is 52 mm/hour; CRP is 26 mg/L. Synovial fluid contains 6,200 leukocytes/µL with 88% neutrophils, no crystals, and a negative Gram stain. Cultures are pending. Which conclusion is best supported before revision planning?

Accepted Answer

Periprosthetic joint infection is likely despite the negative Gram stain.

Answer

The leukocyte count is too low to support infection in a replaced knee.

Answer

The radiolucency identifies aseptic loosening as the cause of the inflammatory findings.

Answer

The absence of fever makes polyethylene wear the more likely explanation for the effusion.

Question 4

An anterior drawer examination appears abnormal after a driver's flexed knee strikes a dashboard. With both knees flexed to 90 degrees, however, the injured tibial plateau starts posterior to the opposite side. Pulling it forward restores the normal tibiofemoral relationship and produces a firm endpoint. Lachman testing is symmetric. What accounts for the misleading anterior drawer result?

Accepted Answer

Reduction of a posteriorly sagged tibia caused by posterior cruciate insufficiency.

Answer

True anterior laxity from an isolated anterior cruciate ligament tear.

Answer

Physiologic anterior translation caused by relaxation of the hamstring muscles.

Answer

Rotatory subluxation caused by an isolated posterolateral corner injury.

Question 5

At a bone-health visit, a 72-year-old postmenopausal woman has a femoral-neck T-score of -1.9 and no prior fragility fracture. Her U.S.-adapted FRAX calculation gives a 10-year hip-fracture probability of 4.6% and a major osteoporotic-fracture probability of 16%. Under Bone Health and Osteoporosis Foundation treatment thresholds, how should these results affect the discussion?

Accepted Answer

Her hip-fracture probability supports offering pharmacologic fracture prevention.

Answer

Medication should be deferred until her T-score reaches -2.5 or lower.

Answer

Both FRAX probabilities must exceed their treatment thresholds before medication is considered.

Answer

A prior fragility fracture is required before preventive medication can be offered.

Question 6

A 13-year-old boy has had three weeks of knee pain and a limp, followed today by sudden worsening that prevents walking even with crutches. The knee is nontender, but the leg rests externally rotated and gentle hip movement causes severe pain. Slipped capital femoral epiphysis is suspected. While urgent orthopaedic care is arranged, which radiographic positioning is appropriate?

Accepted Answer

AP pelvis and cross-table lateral of the affected hip, without forced hip movement.

Answer

AP pelvis and bilateral frog-leg lateral views, with assistance to abduct the painful hip.

Answer

Standing AP pelvis and weight-bearing lateral views to establish the degree of instability.

Answer

AP pelvis and a Dunn lateral view with the affected hip flexed to 90 degrees.

Question 7

"The MRI says the meniscus is torn, so doesn't it need an operation?" asks a 61-year-old with gradually developing knee pain. Weight-bearing films show moderate medial-compartment osteoarthritis; MRI shows a degenerative horizontal meniscal tear. She has full extension, no displaced fragment, and no episodes of true locking. She has tried occasional ibuprofen but no rehabilitation. Which recommendation best addresses her current problem?

Accepted Answer

Begin exercise-based therapy with quadriceps strengthening and activity modification.

Answer

Arrange arthroscopic partial meniscectomy before beginning a strengthening program.

Answer

Use a hinged brace and suspend weight-bearing exercise until the meniscus has healed.

Answer

Refer for knee replacement before attempting additional nonsurgical treatment.

Question 8

An independently mobile 78-year-old remains unable to bear weight after a ground-level fall. Hip radiographs and a noncontrast CT show no fracture. Analgesia relieves her pain at rest, but passive hip rotation still produces deep groin pain. MRI is available today and she has no contraindication. Which study should resolve the remaining concern for an occult fracture?

Accepted Answer

MRI of the affected hip without intravenous contrast.

Answer

Repeat CT of the hip with intravenous contrast.

Answer

Technetium bone scintigraphy after a 72-hour interval.

Answer

Repeat plain hip radiographs at a 10-day follow-up visit.

Question 9

Thirty-six hours after fixation of a femoral shaft fracture, a previously alert 27-year-old becomes confused and tachypneic. Oxygen saturation is 85% on room air, temperature is 38.3°C, and chest imaging shows diffuse bilateral infiltrates. New petechiae are present on the upper chest and conjunctivae. Which postoperative complication best unifies the respiratory, neurologic, and skin findings?

Accepted Answer

Fat embolism syndrome.

Answer

Acute pulmonary thromboembolism.

Answer

Aspiration-related acute lung injury.

Answer

Sepsis-associated disseminated intravascular coagulation.

Question 10

Two days after a ball forces his fingertip into flexion, a 34-year-old has a 25-degree distal interphalangeal extension lag that corrects fully with passive extension. The skin is intact, proximal interphalangeal motion is normal, and radiographs show neither fracture nor joint subluxation. He can comply with splint care. Which initial treatment instruction is correct?

Accepted Answer

Maintain continuous DIP extension for 6-8 weeks while allowing PIP motion.

Answer

Wear a DIP extension splint at night and exercise the DIP joint during the day.

Answer

Immobilize both the DIP and PIP joints continuously in extension for 6-8 weeks.

Answer

Arrange percutaneous pinning because the loss of active DIP extension indicates tendon discontinuity.

Free PA-COS Practice Questions

Domain 2: Fractures/Dislocations 25% of exam

Question 1

Question 2

Domain 3: Infectious Diseases and Connective Tissue Disorders 5% of exam

Question 3

Domain 4: Joint Disorders 20% of exam

Question 4

Question 5

Domain 5: Pediatric 4% of exam

Question 6

Domain 6: Preoperative, Postoperative, and Complication Management 7% of exam

Question 7

Domain 7: Soft-Tissue Injuries and Disorders 25% of exam

Question 8

Question 9

Question 10

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