Dear Medical Students and Foreign Doctors,
I am going to answer the sample USMLE Step 1 Questions with Explanation. These questions are available at USMLE.org.
Question 1
A 14-year-old boy is brought to the emergency department by his parents because of a 1-month history of intermittent right knee pain that has worsened during the past day. He rates his current pain as a 6 on a 10-point scale and says that it worsens when he walks and lessens when he sits. During the past 2 weeks, he has been walking 1 mile daily in preparation for participation in the school marching band. He has not taken any medications for his pain. He sustained a right tibia and fibula fracture at the age of 8 years after a skateboarding accident, which was treated with internal fixation and casting. He has asthma treated with inhaled budesonide daily and inhaled albuterol as needed. His mother has type 2 diabetes mellitus, and his maternal grandmother has osteoporosis. The patient is 170 cm (5 ft 7 in; 77th percentile) tall and weighs 88 kg (195 lb; >95th percentile); BMI is 31 kg/m2 (98th percentile). Temperature is 37.0°C (98.6°F), pulse is 95/min, and blood pressure is 130/80 mm Hg. Physical examination shows hyperpigmented, thickened skin at the nape of the neck. There is tenderness to palpation of the anterior aspect of the right hip and limited range of motion on abduction, internal rotation, and flexion of the right hip. The left hip and knees are nontender; range of motion is full in all directions. The remainder of the examination discloses no abnormalities. Which of the following factors in this patient’s history most increased his risk for developing this condition?
(A) BMI
(B) Family history
(C) Medication use
(D) Previous fractures
(E) Recent physical activity
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Answer
The patient’s BMI is 31 kg/m2, which is in the 98th percentile for his age. A high BMI, especially in the obese range, significantly increases the risk for various musculoskeletal problems, including conditions like osteonecrosis (avascular necrosis) of the femoral head. Obesity puts increased mechanical stress on weight-bearing joints, including the hips and knees, which can lead to the development or exacerbation of musculoskeletal issues such as hip pain and limited range of motion. Therefore, in this case, the patient’s elevated BMI is the most relevant risk factor for his current condition.
The correct answer is A