Intra-sheath vs Extra-sheath Injection for De Quervain's Tenosynovitis

This trial is comparing two methods of delivering a steroid injection for De Quervain's tenosynovitis — a painful condition causing inflammation in the tendons on the thumb side of the wrist. Researchers want to know whether injecting within the tendon sheath (intra-sheath) or just outside it (extra-sheath) gives better pain relief. **You may be eligible if...** - You have been clinically diagnosed with De Quervain's tenosynovitis - Your pain level is at least 40 out of 100 mm on a visual analog pain scale before the injection - You have a life expectancy of more than 1 year - You have not previously had a steroid injection for this condition **You may NOT be eligible if...** - You have already had a steroid injection or surgery for De Quervain's in the same wrist - You have had a failed steroid injection for trigger finger in the past - You are allergic to lidocaine or dexamethasone - You have hypothyroidism or rheumatoid arthritis - You are pregnant Talk to your doctor to see if this trial is right for you.