Intraarticular injection of the interphalangeal joint for therapy of digital mucoid cysts

Mucoid cysts are associated with osteoarthritis (OA) of the digital joints and frequently recur after needle drainage, injection, or surgical ablation. This study determined whether intraarticular injection of the adjacent interphalangeal joint rather than the cyst itself might be effective in resolving digital mucoid cysts. Using paired case series design and sterile technique, 25 consecutive OA digital joints with an adjacent mucoid cyst underwent dorsal non-transtendinous intraarticular injection with a 25-gauge needle and 20-mg triamcinolone acetonide, followed by puncture and manual expression of cyst fluid. Patient pain was measured with the 10-cm Visual Analogue Pain Scale prior to the procedure and at 6 months. Cyst resolution was determined at 6 months and 3 years. The subjects were 61.0 ± 7.7 years old and 60% (15/25) female. Mucoid cysts were adjacent to 19 distal interphalangeal, 3 metacarpophalangeal, and 3 interphalangeal joints. Pre-procedural pain was 4.7 ± 1.0; procedural pain was 6.2 ± 0.6 cm, and post-procedural pain at 6 months was 1.2 ± 0.8 cm (74.5% reduction, 95% CI of difference: 3.0 < 3.5 < 4.0 (p < 0.0001)). 84% (21/25) of the cysts resolved at 6 months; however, 60% (15/25) of the mucoid cysts recurred within 3 years and required retreatment (14 adjacent joints re-injected and 1 ablative cyst surgery). No complications were noted. Intraarticular corticosteroid injection using a dorsal non-transtendinous approach of the joint adjacent to a mucoid cyst is effective resolving cysts and reducing pain at 6 months; however, 60% of mucoid cysts reoccur within 3 years and may require reinjection or surgery.Trial registration: This was not a clinical trial.