In-Office Needle Arthroscopic Synovial Biopsy Is an Effective Diagnostic Tool in Patients With Inflammatory Arthritis

PURPOSE: To assess the utility, safety, and accuracy of in-office needle arthroscopic (IONA) synovial biopsy as a diagnostic tool during treatment of drug-resistant monoarticular inflammatory arthritis of the knee. METHODS: Consecutive patients diagnosed with rheumatoid or psoriatic arthritis with treatment-resistant monoarticular knee involvement who underwent in-office needle arthroscopic synovial biopsy were considered for inclusion. The exclusion criteria were any current malignancies or infection. All patients underwent systematic physical and laboratory examination. IONA was undertaken to inspect the macroscopic appearance of the joint, choose the biopsy site, and classify synovial inflammation. Once collected, synovial tissue specimens were examined histologically using the Krenn scoring system. RESULTS: In total, 12 patients (9 male and 3 female, median age 57 [interquartile range {IQR} 8] years, median disease duration 156 [IQR 201] months) affected by psoriatic arthritis (n = 6) or rheumatoid arthritis (n = 6) were included in this study. Median operating time was 12 (IQR 11) minutes. Three biopsies per patient were collected. The success rate of specimen collection was 97%, the median postoperative 0-10 visual analog scale pain score was 2 (IQR 3), and only one minor complication occurred. CONCLUSIONS: Knee IONA with synovial biopsy is an effective and well-tolerated procedure that can help clinicians formulate specific treatment strategies in patients with refractory pain in the setting of rheumatoid and psoriatic arthritis. LEVEL OF EVIDENCE: IV, Therapeutic case series.