A 63-year-old man comes to the emergency department due to a 2-day history of right knee pain and swelling. The pain is severe enough to interfere with walking. He does not recall any significant trauma to the knee. Medical history is notable for type 2 diabetes mellitus, hypertension, hypercholesterolemia, and mild chronic obstructive pulmonary disease. The patient has a 40-pack-year smoking history and drinks 3-5 alcoholic beverages a night. He is a gardener and frequently works extended hours when on a job. Temperature is 37.2 C (99 F), blood pressure is 115/75 mm Hg, and pulse is 92/min. On examination, there is a dome-shaped swelling anterior to the patella, along with faint erythema and sharp tenderness. Passive range of motion at the knee is normal. X-ray of the knee is shown below: Which of the following is the most likely cause of this patient's acute symptoms?

Question

A 63-year-old man comes to the emergency department due to a 2-day history of right knee pain and swelling.  The pain is severe enough to interfere with walking.  He does not recall any significant trauma to the knee.  Medical history is notable for type 2 diabetes mellitus, hypertension, hypercholesterolemia, and mild chronic obstructive pulmonary disease.  The patient has a 40-pack-year smoking history and drinks 3-5 alcoholic beverages a night.  He is a gardener and frequently works extended hours when on a job.  Temperature is 37.2 C (99 F), blood pressure is 115/75 mm Hg, and pulse is 92/min.  On examination, there is a dome-shaped swelling anterior to the patella, along with faint erythema and sharp tenderness.  Passive range of motion at the knee is normal.  X-ray of the knee is shown below:  Which of the following is the most likely cause of this patient's acute symptoms?

Quizplus · Accepted Answer

11ec25c8_d857_eb8c_bc81_412518983154_MD0003_00 This patient has acute knee pain and tenderness, with an x-ray showing swelling anterior to the patella. This presentation is consistent with acute prepatellar bursitis, which is common in occupations requiring repetitive kneeling (eg, landscaping/gardening, plumbing). swelling anterior to the patella Bursae-synovial sacs alleviating friction at bony prominences and ligamentous attachments-are vulnerable to acute injury or chronic repetitive pressure. Acute prepatellar bursa inflammation (bursitis) may be due to infection (ie, septic bursitis), crystalline arthropathy (eg, gout), or autoimmune conditions (eg, rheumatoid arthritis). Because the bursa is located in an exposed position, exquisite tenderness, swelling and erythema, and painful active range of motion are often present. Passive motion may be normal (as in this patient) because it causes less pressure on the inflamed bursa. Bursitis is generally noninfectious, but ~1/3 cases of acute prepatellar bursitis are due to infection with skin bacteria (eg, due to microtrauma). The affected side depends on individual patient factors (eg, favoring kneeling on one knee rather the other). Bursal fluid aspiration for cell count, Gram stain, and culture is required. If infection is ruled out, patients may be managed with nonsteroidal anti-inflammatory drugs; otherwise, drainage and systemic antibiotics are required. (Choice A) Bursal fluid in prepatellar bursitis should also be examined for urate and calcium pyrophosphate dihydrate crystals. However, crystalline arthropathy (ie, gout, pseudogout) more commonly affects the joint space rather than the bursa, leading to diffuse swelling at the joint rather than focal swelling anterior to it. Also, x-ray in pseudogout typically demonstrates chondrocalcinosis. chondrocalcinosis (Choice B) Patellar fracture presents with acute swelling, tenderness, and inability to extend the knee. It is usually caused by a direct blow or a sudden force under load (eg, fall from a height). (Choice C) Infectious (septic) arthritis presents with acute pain, joint effusion, and fever. Unlike in septic bursitis, the swelling in septic arthritis involves the joint space proper rather than the anterior tissues, and patients have pain with both active and passive range of motion. (Choice D) Patellar tendinitis causes episodic pain at the inferior patella and patellar tendon. It is usually seen in athletes in jumping sports or in occupations with repetitive, forceful knee extension. Although careful inspection of x-ray films may reveal thickening of the patellar tendon, the anterior soft tissues would be normal. (Choice E) Patellofemoral pain syndrome causes chronic anterior knee pain and is most common in women. It presents with peripatellar pain that is worsened by activity or prolonged sitting. Swelling is generally absent; x-rays are usually normal and are done primarily to exclude other causes of knee pain. Educational objective: Prepatellar bursitis is characterized by anterior knee pain, tenderness, erythema, and localized swelling and is common in occupations requiring repetitive kneeling. Bursal fluid analysis should be performed to exclude infection. References: Prepatellar and olecranon bursitis: literature review and development of a treatment algorithm. (http://www.ncbi.nlm.nih.gov/pubmed/24305696)

A 63-Year-Old Man Comes to the Emergency Department Due to a 2-Day