10 USMLE Musculoskeletal and Rheumatology Questions with Answers and Explanations (Set 1)

These 10 USMLE musculoskeletal and rheumatology practice questions cover crystal arthritis, knee and wrist injuries, osteoporosis, fibromyalgia, giant cell arteritis, sarcoidosis, drug-induced myopathy, crutch palsy and carpal tunnel anatomy. Each question includes the correct answer and an explanation.

Written by Dr. Ray Makar, MD, author of the Repeated USMLE Questions eBook series.

Prefer video? Watch daily USMLE case questions on MedFocus by Dr. Ray on YouTube.

How to use this page: read the question, pick your answer, then tap Show Answer and Explanation.

Questions

Question 1. An 83-year-old man presents to the clinic with progressive pain and swelling of the left knee for 8 months. He has a history of well-controlled type 2 diabetes for 15 years. He does not smoke or take any recreational drugs. He drinks alcohol socially. His surgical and family histories are unremarkable. Physical examination reveals a medial parapatellar hard movable mass and limited movement of the left knee. Excisional biopsy of the mass reveals glossy white calcified deposits, which show positive birefringence under polarized light. What is the most likely diagnosis?

A- Gout
B- Pseudogout
C- Osteoarthritis
D- Acute arthritis
E- Osteosarcoma

Calcified deposits, which show positive birefringence under polarized light, are calcium pyrophosphate. This is a typical presentation of pseudogout.
Gout deposits show negative birefringence. Osteoarthritis, acute arthritis and osteosarcoma show different clinical pictures and biopsies.
The correct answer is B

 

Question 2. A 26-year-old woman visits her physician with a complaint of discomfort in her left knee for 2 weeks. It is exaggerated when she is sitting for a long time and relieved with analgesics. She admits that she had this discomfort on and off since she was at high school. On examination, the left knee does not show any signs of inflammation. It shows induration and tenderness on the back of the knee. X-ray shows local opacity on the back of the left knee joint. What is the most likely diagnosis?

A- Acute arthritis
B- Hydrarthrosis
C- Baker cyst
D- Tear of posterior collateral ligament
E- Osteoarthritis

This is a typical presentation of Baker cyst. It has been there for a long time and shows symptoms only during inflammation. Physical examination and x-ray are diagnostic.
The correct answer is C

 

Question 3. A 70-year-old man is brought to the doctor having a sudden onset of severe lower back pain. Upon conducting a physical examination of the patient, severe kyphosis is revealed. An x-ray of the back shows a compression fracture in the lumbar area of a vertebral body. This is followed by marked thinning of the bones as well. Laboratory tests measuring serum calcium, alkaline phosphatase, phosphorus, and parathyroid hormone levels, all come back within the normal range. What is the most likely reason behind the bone changes in the patient?

A- Osteitis fibrosa cystica
B- Osteoporosis
C- Osteopetrosis
D- Osteomalacia

The likely diagnosis for the patient is osteoporosis. This is a condition wherein the bones become fragile and have a higher risk of fracture. In a normal human being, the bone mass or density starts decreasing after 35 years of age. Lack of calcium, vitamin D, exercise, as well as genetics, can increase the risk of having osteoporosis. The diagnosis of osteoporosis can be confirmed by x-rays and tests for measuring bone density. Osteitis fibrosa cystica is a common complication of hyperparathyroidism. Serum calcium and parathyroid hormone should be high which is not the case in this patient.
The correct answer is B

 

Question 4. A 21 year old college student was playing basketball with his friends when he fell on his outstretched right hand with the palm down. He stood up and continued playing. After 2 days, he felt swelling and tenderness of his right palm without any deformity. On examination, there is tenderness to deep palpation on the anatomical snuffbox of his right hand. What is the most likely diagnosis of this patient?

A- Colles fracture
B- Scaphoid fracture
C- First metacarpal bone fracture
D- Tear of opponens pollicis

This is a very common injury in sports. The description of injury is typical of scaphoid fracture. It is medically significant as the blood supply to the scaphoid could be interrupted causing necrosis to a part of the bone. Other injuries mentioned above are common but they show other clinical features.
The correct answer is B

 

Question 5. A 25-year-old woman presents to the clinic complaining of general aches for two years. Pain is getting worse over the past 3 months. Every morning, she has stiffness all over her body, which is usually relieved in about 5-10 min. She has no history of trauma or any medical condition. Her BMI is 21 and she has no rash or joint swelling. She has multiple tender points. All laboratory investigations are within normal limits. What is the most appropriate management of this patient?

A- Perform electromyogram (EMG)
B- Perform nerve conduction studies
C- Start duloxetine
D- Start hydrocodone
E- Start prednisone

This patient most likely has fibromyalgia. It is diagnosed clinically depending on the presence of multiple tender points with the absence of any rash or joint swelling. The treatment of choice of fibromyalgia is duloxetine as it is approved to have positive results in many cases. In case of failure of medical treatment, investigations as EMG and nerve conduction studies can be done to exclude other conditions.
The correct answer is C

 

Question 6. A 74-year-old woman visits her physician complaining of a new onset of fatigue and temporal headache. She lost about 5-7 pounds over the last year. She also has morning stiffness for one hour accompanied by aching in the shoulders and hips. She noticed that her vision was deteriorating during the last year. Physical examination is unremarkable. Laboratory tests indicate high erythrocyte sedimentation rate. What is the most appropriate next step?

A- CT scan of the head
B- Carotid Doppler studies
C- Temporal artery biopsy
D- Start prednisone
E- Refer to a neurologist

This patient has a typical presentation of giant cell arteritis (temporal arteritis). She should start immediately taking prednisone orally otherwise she will lose her vision permanently. Clinical picture and high ESR are enough for diagnosis. In some cases of doubt, temporal artery biopsy can be performed. CT scan of the head and carotid Doppler studies are not helpful in diagnosis of temporal arteritis.
The correct answer is D

 

Question 7. A 42-year-old African-American woman presents to the clinic because of dyspnea that worsens over the last 6 months. She has no fever, chest pain or loss of weight. The patient works as a preschool teacher. Physical examination is unremarkable. Chest x-ray shows bilateral hilar lymphadenopathy. What is the most likely diagnosis?

A- Asbestosis
B- Pneumonia
C- Sarcoidosis
D- Tuberculosis
E- Lung cancer

This patient has a typical presentation of sarcoidosis. She is an African American. There is dyspnea and no fever, pain or loss of weight. X-ray is also typical for sarcoidosis.
The correct answer is C

 

Question 8. A 28-year-old woman visits her physician for evaluation of bilateral proximal muscle weakness and muscle pain. Her symptoms started last week, and her pain is getting worse. Her records indicate alcohol abuse and cocaine addiction. She is HIV positive and she takes zidovudine. She also takes simvastatin for hypercholesterolemia. A muscle biopsy shows significant changes in mitochondrial histology. What is the most likely etiology of this patient’s condition?

A- Alcohol abuse
B- Cocaine addiction
C- Zidovudine
D- Simvastatin
E- HIV infection

This patient presents with proximal muscle weakness, myalgia, and mitochondrial changes on muscle biopsy, which are classic signs of mitochondrial myopathy.
Zidovudine, a nucleoside reverse transcriptase inhibitor (NRTI) used in HIV treatment, is well known for causing mitochondrial toxicity. It inhibits mitochondrial DNA polymerase-γ, leading to impaired oxidative phosphorylation and muscle cell damage.
The correct answer is C
Read this Pharmacology MCQs Book

 

Question 9. A 20-year-old male athlete complains of pain and weakness in his right arm. He had a successful surgery on his knee last week. He has been walking with the aid of crutches since then. On examination, he is unable to extend his right arm at the elbow or the hand at the wrist. There is also a sensory deficit over the dorsolateral area of the right hand. Neurological examination is otherwise normal. Which nerve is most likely related to his symptoms?

A- Axillary nerve
B- Median nerve
C- Radial nerve
D- Suprascapular nerve
E- Ulnar nerve

This is a typical presentation of radial nerve palsy caused by the compression of the crutches on the radial nerve. It is also called crutch paralysis. Crutch paralysis occurs when the radial nerve becomes under constant pressure by the use of a crutch. It leads to paralysis of the muscles that innervated by the compressed nerve. Generally, crutches which are not adjusted to the correct height causes the radial nerve to be constantly pushed against the humerus. This can cause wrist drop, in which the fingers, hand, or wrist is flexed because the radial nerve cannot innervate the extensor muscles. This condition, like other injuries from compressed nerves, normally improves quickly without any consequences.
The correct answer is C

 

Question 10. A 45-year-old woman visits her physician with a complaint of pain and fatigue in her wrist and hand for 6 weeks. MRI confirms the diagnosis of carpal tunnel syndrome. What is the structure that forms the anterior wall of the carpal tunnel?

A- Skin
B- Superficial fascia
C- Palmar aponeurosis
D- Flexor retinaculum
E- Extensor retinaculum

Flexor retinaculum forms the anterior wall of the carpal tunnel. It is also known as the transverse carpal ligament.
The correct answer is D

 

High-yield points from this set

  • Positively birefringent rhomboid crystals = calcium pyrophosphate (pseudogout); gout crystals are negatively birefringent needles.
  • A swelling behind the knee = Baker (popliteal) cyst.
  • Vertebral compression fracture with normal calcium, phosphate, ALP and PTH = osteoporosis.
  • Snuffbox tenderness after a fall on an outstretched hand = scaphoid fracture (risk of avascular necrosis).
  • Widespread pain with tender points and normal labs = fibromyalgia; duloxetine, pregabalin or exercise.
  • Temporal headache, vision changes and high ESR in an older woman = giant cell arteritis: start steroids right away.
  • Bilateral hilar lymphadenopathy in an African-American woman = sarcoidosis.
  • Zidovudine can cause a mitochondrial myopathy.
  • Crutch pressure in the axilla injures the radial nerve (wrist drop).
  • The flexor retinaculum (transverse carpal ligament) forms the roof of the carpal tunnel.

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