Evaluation for septic arthritis of the native adult knee is aided by multivariable assessment

The Effect of Crystal Arthropathy on the Diagnostic Criteria of Native Septic Arthritis

INTRODUCTION

Distinguishing between septic arthritis and crystal arthropathy flares can be challenging. The purpose of this study was to determine how the presence of synovial crystals affects the diagnostic criteria of septic arthritis.

METHODS

A retrospective review identified patients undergoing joint aspirations to rule out native septic arthritis. Differences between septic arthritis presenting with and without synovial crystals were analyzed. A receiver-operating characteristic curve was plotted for laboratory markers to determine the area under the curve, or diagnostic accuracy, for septic arthritis and to evaluate thresholds that maximized sensitivity and specificity.

RESULTS

There were 302 joint aspirations in 267 patients. Septic arthritis was diagnosed in 17.9% (54/302). Patients with synovial crystals were less likely to have septic arthritis (4.2% [5/119] vs. 26.8% [49/183], P < 0.0001). Septic arthritis in patients with no synovial crystals was associated with fever and a higher synovial white blood cell (WBC) count, synovial polymorphonuclear cell percentage (PMN%), serum WBC, and C-reactive protein (CRP) ( P < 0.05). Septic arthritis in patients with synovial crystals was only associated with inability to bear weight and a higher synovial WBC and CRP ( P < 0.05). Synovial PMN% was considered nondiagnostic of septic arthritis (area under the curve 0.56) in patients with crystals while synovial WBC and CRP had acceptable (0.76) and excellent (0.83) diagnostic utility, respectively. The WBC and CRP value thresholds that maximized sensitivity and specificity for septic arthritis were greater in patients with crystals (21,600 vs. 17,954 cells/μL and 125 vs. 69 mg/L, respectively).

DISCUSSION

The presence of synovial crystals reduced the likelihood of septic arthritis and altered the laboratory diagnostic criteria. PMN% was nondiagnostic in the setting of synovial crystals.

An update on recent progress of the epidemiology, etiology, diagnosis, and treatment of acute septic arthritis: a review

Acute septic arthritis is on the rise among all patients. Acute septic arthritis must be extensively assessed, identified, and treated to prevent fatal consequences. Antimicrobial therapy administered intravenously has long been considered the gold standard for treating acute osteoarticular infections. According to clinical research, parenteral antibiotics for a few days, followed by oral antibiotics, are safe and effective for treating infections without complications. This article focuses on bringing physicians up-to-date on the most recent findings and discussions about the epidemiology, etiology, diagnosis, and treatment of acute septic arthritis. In recent years, the emergence of antibiotic-resistant, particularly aggressive bacterial species has highlighted the need for more research to enhance treatment approaches and develop innovative diagnosis methods and drugs that might combat better in all patients. This article aims to furnish radiologists, orthopaedic surgeons, and other medical practitioners with contemporary insights on the subject matter and foster collaborative efforts to improve patient outcomes. This review represents the initial comprehensive update encompassing patients across all age groups.

Raised initial total white cell count and lower post-operative decline of C reactive protein increases the risk of secondary surgery in septic arthritis of the native knee

PURPOSE

Septic arthritis is an orthopaedic emergency with high morbidity and mortality. The aim of this study is to determine the risk factors associated with secondary surgery for septic arthritis of the native knee joint.

METHODS

This is a retrospective study reviewing all patients who underwent surgery for septic arthritis of the knee from 2012 to 2019 in a single institution. A total of 117 patients were recruited. Patients were divided into 2 groups: Group I (79/117, 67.5%) underwent one surgery and Group II (38/117, 32.5%) underwent more than one surgery.

RESULTS

Patients with a raised initial total white (TW) cell count of > 20 × 10⁹/L had a significantly higher risk of secondary surgery. (Adjusted hazard ratio 2.42, p < 0.05) A decline of CRP level of less than 20% within 24 h from initial operation was also a risk for secondary surgery. (Adjusted hazard ratio 0.34, p < 0.01) Patients in group II also had significantly higher post-operative median TW cell count and neutrophil count. There was no significant difference in the offending microbe, surgical approach, and duration of operation from initial presentation between the groups.

CONCLUSIONS

Patients with septic arthritis of the native knee joint who present with raised initial total white cell count of > 20 × 10⁹/L and decline of CRP level of less than 20% within 24 h from initial operation are at higher risk of secondary operation. In these patients, more aggressive treatment strategies and appropriate counselling on the risks of repeated surgery are recommended.

LEVEL OF EVIDENCE

Level IV.