Misdiagnosed Knee Pain: Unmasking Gout Through Synovial Aspiration in an Outpatient Setting - A Case Report

Friday, October 24, 2025

8:00 AM - 9:15 AM MT

Location: Kiosk 3

Primary Author(s)

Fatimah Mozawalla, MD (she/her/hers)

Resident Physician
Icahn School of Medicine At Mount Sinai PM&R Program
New York, New York

Co-Author(s)

EF

Emily Fatakhov, MD

Assistant Professor, Medical Director PM&R Queens and Long Island
Icahn School of Medicine At Mount Sinai, New York

Poster Presenter(s)

Abby J. Ventura, MBA, MD

PM&R Resident Physician
Mount Sinai Hospital PM&R Residency Program
New York, New York

Co-Author(s)

Ely G. Cuberos Paredes, MS (she/her/hers)

Medical Student
Burrell College of Osteopathic Medicine
Woodside, New York

Disclosure(s):

Fatimah Mozawalla, MD: No financial relationships to disclose

Abby J. Ventura, MBA, MD: No financial relationships to disclose

Ely G. Cuberos Paredes, MS: No financial relationships to disclose

Case Diagnosis: Gout

Case Description or Program Description: A 60-year-old male with a history of uric acid renal stones presented with six months of intermittent right knee pain. The pain, alternating between sharp and aching, was worsened by stairs and prolonged walking, and accompanied by swelling, but no instability or systemic symptoms. Relief was achieved with warm showers, rest, and NSAIDs.

Setting: Sports Medicine Clinic

Assessment/Results: X-rays of the right knee revealed joint space chondrocalcinosis and osteophytes, with no fractures. Prior rheumatologic workup, including multiple serum uric acid tests, was unremarkable. Exam revealed a right knee effusion limiting motion, but no tenderness, normal strength, and negative McMurray and Lachman tests. Given persistent pain and effusion, an MRI and knee aspiration were performed.

MRI showed significant effusion with synovitis, mild patellofemoral chondrosis, and subchondral narrowing, without fractures or tears. Synovial analysis confirmed monosodium urate crystals, leading to a diagnosis of gout despite normal serum uric acid. The patient improved with Naproxen, declined colchicine, and was referred to rheumatology, with physical therapy deferred for gout management.

Discussion (relevance): This case highlights the importance of diagnostic aspiration in unexplained knee pain and swelling, even with normal serum uric acid levels and absent classic gout symptoms. While gout commonly affects the first metatarsophalangeal joint, the knee is involved in approximately 1o to 50 percent of cases. Relying solely on clinical presentation, imaging, or serum uric acid levels in outpatient settings may lead to misdiagnosis. Therefore, broader use of diagnostic aspirations, should be utilized to differentiate gout from osteoarthritis, particularly in at-risk patients, thus ensuring appropriate treatment.

Conclusions: For unexplained knee pain and effusion, synovial fluid analysis should be performed regardless of serum uric acid levels to improve diagnostic accuracy and rule out emergent conditions like septic arthritis. Early diagnosis ensures timely treatment and helps prevent unnecessary intra-articular steroid injections.