Gyrus Daily Questions; Internal Medicine #18

[cingulate.gyrus]

A 62-year-old white male presents with a chief complaint of right knee pain and swelling. Past medical history is significant for obesity with a body mass index (BMI) of 34 kg/m2, diet-controlled type 2 diabetes mellitus, and hypertension. His medications include hydrochlorothiazide and acetaminophen as needed for pain. Physical examination is remarkable for a moderate-size effusion of the right knee, with range of motion limited to 90° of flexion and 160° of extension. There is minimal warmth and no redness. He has crepitus with range of motion. With weight bearing, he has outward bowing of the legs bilaterally. A radiogram of the right knee shows osteophytes and joint space narrowing. Which of the following is the most likely finding on joint fluid examination?

A. A Gram stain showing gram-positive cocci in clusters
B. A white blood cell count of 1110/mm3
C. A white blood cell count of 22,000/mm3
D. Positively birefringent crystals on polarizing light microscopy
E. Negatively birefringent crystals on polarizing light microscopy

[K06100]

I think B........

[XpaezX]

B, this dude has OA

A = septic arthritis
C = Vague, can be anything, from pseudogout, gout, wannabe septic arthritis, inflammatory conditions, trauma.
D= Pseudogout
E= Gout

[cingulate.gyrus]

The answer is B.
white blood cell count of 1110/mm3


This patient has degenerative arthritis. His obesity predisposes him to degenerative joint disease that will be worse in the large weight-bearing joints. The physical examination findings of decreased range of motion, crepitus, and varus deformity that is exacerbated on weight bearing are consistent with this diagnosis.

The radiogram of the knee demonstrates narrowing of the joint space with osteophyte formation. Occasional effusions may be seen, especially after overuse injuries.

The joint fluid analysis in patients with degenerative disease reveals a clear, viscous fluid with a white blood cell count less than 2000/μL.

Positively birefringent crystals on polarizing light microscopy will be seen in pseudogout that most commonly affects the knee,

whereas negatively birefringent crystals are characteristic of gout. Joint fluid in these inflammatory conditions would generally have a white blood cell count of less than 50,000/ mm3 and is yellow and turbid in character.

Septic arthritis presents with fevers and a very warm and tender joint. The joint fluid can have the appearance of frank pus and is opaque. The white blood cell count is usually higher than 50,000/mm3 and can have a positive Gram stain for organisms.