This protocol describes combined medical and surgical management for diagnosing and treating gouty arthritis complicated by septic arthritis.
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Case Report
This protocol describes combined medical and surgical management for diagnosing and treating gouty arthritis complicated by septic arthritis.
Gouty knee arthritis shares numerous clinical similarities with septic knee arthritis. Core overlapping manifestations include sudden onset of unilateral knee symptoms such as redness, swelling, heat, and pain, accompanied by significant functional impairment and restricted mobility. Inflammatory markers like erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are often markedly elevated in both conditions. Early imaging studies typically fail to reveal bone destruction. Due to highly overlapping clinical presentations, misdiagnosis between the two conditions is common, often requiring joint aspiration and synovial fluid analysis for definitive diagnosis. This report describes a case of gouty arthritis complicated by suppurative arthritis. The patient presented with a sudden onset of swelling and pain in the right knee lasting 2 days, accompanied by increased skin temperature and limited mobility. The patient had no prior history of gout and was otherwise in good health. Routine synovial fluid analysis showed a white blood cell count of 4+ and a red blood cell count of 1+. Culture identified Staphylococcus aureus (MRSA) in the sample. After vancomycin treatment, symptoms significantly improved, and the patient was discharged 1 week later. However, 2 days post-discharge, the patient returned with recurrent knee swelling and pain. Following a multidisciplinary consultation, arthroscopic debridement was performed. Intraoperative findings revealed extensive chalky crystal deposits within the joint cavity. Postoperative pathology confirmed gouty arthritis. The patient was discharged after symptom resolution following postoperative allopurinol therapy to reduce uric acid levels. This case underscores the importance of early differentiation between gouty arthritis and septic arthritis in clinical practice, as well as the necessity of scientific management.
Gouty arthritis (GA) is an inflammatory disease caused by the deposition of monosodium urate (MSU) crystals in the joints, surrounding soft tissues, tendons, and other sites. Clinically, it manifests as acute joint redness, swelling, and pain, initially affecting a single joint, with 50% of cases occurring in the first metatarsophalangeal joint1. Gout predominantly affects the lower extremities, such as the dorsum of the foot, heel, ankle, and knee joints, though the fingers, elbows, wrists, and shoulders may also be involved2,3. Statistics indicate that the prevalence of gout in Western countries ranges from 2.7% to 6.7%, reaching 9.7% in individuals over 80 years old. In China, the prevalence is approximately 1.1%, but with changes in dietary patterns, the incidence of gouty arthritis shows an increasing trend year by year4,5. Even in the United States, the prevalence of gout has nearly doubled over the past few decades6.
Acute gout attacks, also termed acute aseptic inflammation, involve an acidic internal environment and MSU crystal-activated signaling pathways in macrophages and neutrophils. This leads to a massive accumulation of these cells within the joint cavity, making concurrent septic arthritis highly unlikely during gout attacks7. However, the presence of MSU crystals does not preclude infection8,9,10. Studies indicate that among patients with monoarticular gout, the incidence of infectious arthritis complicating crystal-induced arthropathy ranges from 1.5% to 5.2%11,12. Previous reports have described GA complicated by septic arthritis (SA), but these cases all had relevant histories, such as prior gout, long-term steroid use, or surgical history13,14,15. In our case, the patient had no relevant history, and the onset was extremely rapid. Under combined medical and surgical management, the patient's symptoms improved significantly, function was restored, and the patient ultimately recovered and was discharged.
Case presentation
A 46-year-old patient presented with swelling and pain in the right knee joint for 2 days. On examination, the right knee exhibited pain, redness, elevated skin temperature, limited range of motion, low-grade fever, and night sweats. The patient reported that the knee pain began after a cold, with an intensity of 10/10 on the pain scale, worsening with activity. The patient is otherwise healthy with no significant medical history. On admission, the patient's temperature was 100.4 °F (38.0 °C), blood pressure was 149/88 mmHg, and heart rate was normal. Cardiac, pulmonary, abdominal, and neurological examinations were unremarkable. Physical examination revealed swelling of the suprapatellar pouch on the right knee with elevated skin temperature. Both active and passive range of motion were restricted. Muscle strength in both lower extremities was normal. Distal pulses in both limbs were present. Pathological reflexes were absent. Upon admission, an emergency magnetic resonance imaging (MRI) was performed, and blood and joint fluid samples were collected for testing (Table 1, Figure 1).
Synovial fluid culture was initiated immediately upon admission. The joint fluid appeared pale yellow. Given the patient's elevated inflammatory markers, we promptly administered coverage therapy with linezolid plus levofloxacin. After 3 days, the synovial fluid culture identified methicillin-resistant MRSA, prompting antibiotic adjustment to vancomycin. The patient's symptoms gradually improved. After 1 week, blood tests and synovial fluid culture were repeated (Table 1), with the synovial fluid culture returning negative. The patient was discharged after 1 week of treatment with vancomycin tablets.
After 2 weeks, the patient presented again with swelling and pain in the right knee. On examination, the right knee remained painful, red, and warm to the touch, with marked limitation of movement and severe pain. Upon admission, the patient's temperature was 99.5 °F (37.5 °C), with normal heart rate and blood pressure. Cardiac, pulmonary, abdominal, and neurological examinations were unremarkable. Blood and joint fluid samples were collected for further analysis (Table 2, Figure 2). Intravenous vancomycin therapy was initiated. Concurrently, a multidisciplinary consultation was convened. Tuberculosis antibody testing and Mycobacterium tuberculosis/Rifampin (MTB/RIF) assay were performed, yielding negative results that ruled out knee tuberculosis. Additional tests, including Human Leukocyte Antigen B27 (HLA-B27), Cyclic Citrullinated Peptide (CCP), antinuclear antibody (ANA), RF, and Antistreptolysin O (ASO), were conducted, all of which were negative, excluding rheumatoid arthritis and autoimmune diseases. Following a multidisciplinary discussion, surgical intervention was decided. We performed arthroscopic lavage and synovectomy of the right knee, placing one medicated catheter and one drainage tube. Intraoperatively, we observed diffuse synovial congestion and edema with extensive white, chalky crystals throughout the joint cavity. Three soft tissue samples were obtained for microbiological culture, one of which grew MRSA. Postoperative pathology revealed extensive neutrophilic infiltration and abscess formation with a foreign body giant cell reaction, consistent with gouty arthritis. After 1 week of catheter irrigation with negative synovial fluid cultures, the medication catheter and drainage tube were removed. Follow-up blood tests showed improved blood parameters (Table 2).
Diagnosis, Assessment, and Plan:
During the 1st hospitalization, we diagnosed a knee joint infection caused by MRSA. Initial treatment involved coverage with linezolid plus levofloxacin. After the synovial fluid culture results returned, we switched to vancomycin therapy. The 2nd hospitalization revealed a diagnosis of gouty arthritis complicated by knee joint infection based on postoperative pathology findings. Postoperatively, we irrigated the joint cavity with vancomycin for 1 week while administering intravenous vancomycin for infection control and etoricoxib for pain relief. Once pain subsided, we initiated allopurinol 20 mg orally once daily to lower uric acid levels. Following discharge, vancomycin was continued for 4 weeks to combat infection, with long-term uric acid control maintained at 180-300 µmol/L.
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Written informed consent for the use of medical history and clinical images was obtained from patients in accordance with institutional guidelines. Patient identifiers are anonymized in all documentation. This study was reviewed and approved by the Ethics Committee, approval number: 2025-KLS-511-01. This case report and any accompanying images have been published with the patient's written informed consent.
1. Patient preparation
2. Clinical and radiological examination
3. Synovial fluid aspiration and laboratory tests
4. Medical management
5. Surgical intervention
6. Discharge and follow-up
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On initial admission, the patient exhibited right knee swelling, warmth, erythema, and pain rated 10/10. MRI revealed joint effusion and synovial thickening without bone destruction. Synovial fluid appeared turbid yellow, with a markedly elevated leukocyte count. Culture identified MRSA. Empirical antibiotics were adjusted to vancomycin, resulting in a gradual improvement of symptoms and normalization of inflammatory markers. The patient was discharged after 1 week of treatment.
At 2 weeks pos...
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This case lacks the typical symptoms and signs of GA, which commonly affects the first metatarsophalangeal joint and is often associated with elevated serum uric acid levels17. This case presented with knee swelling and pain, normal serum uric acid levels, and although no urate crystals were identified in the joint aspirate, elevated white blood cells (WBC), CRP, and procalcitonin suggested infection. Antibiotic therapy was effective but incomplete, as persistent intra-articular inflammation persi...
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The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The authors have nothing to disclose.
This work was supported by the National Natural Science Foundation of China (82074469). Natural Science Foundation of Zhejiang Province (LY21H270008). 2024 Zhejiang Chinese Medical University Cultivation Plan for Top Innovative Talents of Postgraduates (721100G00747)
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| Name | Company | Catalog Number | Comments |
|---|---|---|---|
| 1.5-Tesla MRI Scanner | Siemens Healthineers | MAGNETOM Essenza | |
| Allopurinol Tablets | GlaxoSmithKline | 500790 | |
| Antinuclear Antibody (ANA) Assay | Thermo Fisher Scientific | 2401-0001 | |
| Antistreptolysin O (ASO) Test | Abbott Laboratories | 7D55-20 | |
| Arthroscopy Shaver | Stryker Corporation | 272-300-100 | |
| Blood Agar Plate | BD Diagnostics | 221261 | |
| Blood Culture Bottle (Aerobic) | BD Diagnostics | 442020 | |
| Blood Culture Bottle (Anaerobic) | BD Diagnostics | 442021 | |
| CCP ELISA | Axis-Shield Diagnostics | FCCP600 | |
| Chocolate Agar Plate | bioMérieux | 43101 | |
| Complete Blood Count Reagent Kit | Sysmex Corporation | XN-9000 series | |
| C-Reactive Protein (CRP) Assay | Roche Diagnostics | 4628918190 | |
| Drainage Tube (Surgical) | Medtronic | 8888173031 | |
| Erythrocyte Sedimentation Rate (ESR) Kit | Streck | 107760 | |
| Etoricoxib Tablets | Merck & Co. | 100 mg, NDC 0006-0372 | |
| Formalin Solution (10%) | Sigma-Aldrich | HT501128 | |
| Gram Stain Kit | Hardy Diagnostics | G100 | |
| Hematoxylin and Eosin (H&E) Stain | Sigma-Aldrich | HHS128 & HT110116 | |
| HLA-B27 Antibody Reagent | BD Biosciences | 340183 | |
| Levofloxacin Injection | Janssen Pharmaceuticals | NDC 50458-050-01 | |
| Linezolid Injection | Pfizer | NDC 0009-4992-01 | |
| Medication Catheter (Intra-articular) | Smith & Nephew | 72202866 | |
| Paraffin Wax | Leica Biosystems | 3801310 | |
| Procalcitonin (PCT) Assay | Brahms GmbH | KRYPTOR PCT | |
| Rheumatoid Factor (RF) Test | Beckman Coulter | 467858 | |
| Synovial Fluid Collection Tube | Sarstedt | 82.1190.001 | |
| Tuberculosis Antibody Test | Standard Diagnostics | TB Ab Rapid 11FK10 | |
| Ultrasound Machine | GE Healthcare | LOGIQ E10 | |
| Vancomycin Hydrochloride | Mylan Pharmaceuticals | NDC 67457-156-60 | |
| Xpert MTB/RIF Assay | Cepheid | GXMTB/RIF-10 |
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