A 72-year-old man is admitted to the hospital overnight following an elective inguinal hernia repair. There are no immediate postoperative complications, but he awakens the next morning with severe right knee pain. Medical history is notable for hypertension, chronic obstructive pulmonary disease, and mild aortic stenosis. The patient smokes half a pack of cigarettes daily and drinks alcohol on social occasions. His temperature is 38.1 C (100.5 F), blood pressure is 160/110 mm Hg, pulse is 80/min, and respirations are 16/min. Physical examination shows redness and swelling of the right knee with limited motion due to pain. Diagnostic arthrocentesis is performed, with results from synovial fluid analysis as follows: Which of the following is most likely associated with this patient's current condition?

Question

A 72-year-old man is admitted to the hospital overnight following an elective inguinal hernia repair.  There are no immediate postoperative complications, but he awakens the next morning with severe right knee pain.  Medical history is notable for hypertension, chronic obstructive pulmonary disease, and mild aortic stenosis.  The patient smokes half a pack of cigarettes daily and drinks alcohol on social occasions.  His temperature is 38.1 C (100.5 F), blood pressure is 160/110 mm Hg, pulse is 80/min, and respirations are 16/min.  Physical examination shows redness and swelling of the right knee with limited motion due to pain.  Diagnostic arthrocentesis is performed, with results from synovial fluid analysis as follows:  Which of the following is most likely associated with this patient's current condition?

Quizplus · Accepted Answer

11ec25c8_d518_c54d_bc81_190c5e46b5fd_MD0003_00 Pseudogout is a form of acute arthritis induced by the release of calcium pyrophosphate dihydrate (CPPD) crystals from sites of chondrocalcinosis (calcification of articular cartilage) into the joint space. It often occurs in the setting of recent surgery or medical illness. Patients present with acute pain, swelling, redness, and limited motion of the involved joint(s), with the knee most commonly affected. Fever and a mild leukocytosis may occur in pseudogout, although these findings are less common than in urate gout. Identifying chondrocalcinosis on x-ray of a joint with acute arthritis establishes a diagnosis of probable CPPD crystal arthritis. Synovial fluid analysis will show an inflammatory effusion (15,000-30,000 cells/mm³). The rhomboid-shaped, positively birefringent crystals of CPPD can be difficult to detect on synovial fluid analysis but are diagnostic when present. chondrocalcinosis crystals (Choice A) Reactive arthritis is classically characterized by oligoarthritis, nongonococcal urethritis, and conjunctivitis. It usually follows an acute gastrointestinal (eg, Salmonella, Yersinia) or genitourinary (eg, Chlamydia) infection and causes subacute to chronic, rather than acute, symptoms. (Choice B) Heberden nodes are enlarged bony spurs that occur at the distal interphalangeal joints in osteoarthritis. Typical imaging findings include joint space narrowing, osteophytes, and subchondral sclerosis. Chondrocalcinosis and synovial crystals are not classically associated with idiopathic osteoarthritis. (Choice D) Rheumatoid factor is a serologic marker for rheumatoid arthritis, which typically presents with subacute to chronic, symmetric polyarthritis predominantly affecting the small joints of the hands. (Choice E) Tophi are extra-articular collections of urate crystals in patients with chronic gout. Gout may resemble pseudogout clinically, but it is distinguished by needle-shaped (not rhomboid), negatively birefringent crystals. crystals (Choice F) Septic arthritis is a possible consequence of transient perioperative bacteremia. However, symptoms are typically progressive over a few days rather than abrupt, and synovial fluid would show organisms on Gram stain and a more pronounced leukocytosis (>50,000 cells/mm³). Educational objective: Pseudogout is an acute inflammatory arthritis caused by calcium pyrophosphate crystals. It often occurs in the setting of surgery or medical illness. Pseudogout is diagnosed with synovial fluid showing rhomboid-shaped, positively birefringent crystals and radiographic evidence of chondrocalcinosis (calcified articular cartilage).

A 72-Year-Old Man Is Admitted to the Hospital Overnight Following