Intra-sheath versus extra-sheath ultrasound guided corticosteroid injection for trigger finger: a triple blinded randomized clinical trial

Objective: The aim of this study is to compare clinical results of ultrasound-guided corticosteroid injection, intra-sheath versus extra-sheath of the finger flexor tendon. Methods: A total of 166 patients with trigger finger were evaluated in a triple blind randomized clinical trial study. All the patients were injected with 1ml of 40mg/ml methyl prednisolone acetate, under the guidance of ultrasound. Half the patients were injected extra sheath, while the other half were injected intra sheath at the level of first annular pulley. Results: The two groups were comparable in baseline characteristics (age, gender, dominant hand, involved hand and finger, and the symptoms duration). No significant difference was observed in the two groups with regards to Quinnell grading. In the final visit, 94% of patients from each group were symptom free. Conclusion: Results of corticosteroid injection intra-sheath or extra-sheath of the finger flexor tendon under ultrasound guidance in patients with trigger finger are comparably alike. Extra-sheath injection at the level of A1 pulley is as effective as an Intra-sheath administration.