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

Null Hypothesis: Extra-sheath steroid injections are inferior to intra-sheath steroid injections in the treatment of DeQuervain's tenosynovitis.

Alternative Hypothesis:Extra-sheath steroid injections are not inferior to intra-sheath steroid injections in the treatment of De Quervain's tenosynovitis.

Background:

DeQuervain's Tenosynovitis is a common condition with an estimated incidence of 0.5% in men and 1.3% in women, usually occurring in the third or fourth decade of life. The condition involves accumulation of mucopolysaccharide in the first dorsal compartment of the wrist, narrowing the passageway through which the abductor pollicis longus (APL) and extensor pollicis brevis (EPB) tendons pass(1). Patients typically present with pain over the radial styloid that is often exacerbated by grasping, thumb abduction and ulnar deviation of the wrist. The degree of pain can be measured using the visual analog scale (VAS).

The VAS pain scale is a widely used test to effectively measure pain(9). The visual analog scale we will be using is a 100mm horizontal line with no numbers and only written descriptors on either end of the line. The written descriptor on the left side of the line will be "no pain" and the descriptor on the right will be "pain as bad as it could possibly be". Patients will be instructed to make a mark on the line where they believe their current pain fits. The patient's response will be measured and recorded.

Currently the most effective treatment modality for this condition is ultrasound guided injection of corticosteroids directly into the sheath where the APL and EPB pass. However, we hypothesize that injecting corticosteroids outside the sheath will not be inferior. Our rationale for this hypothesis lies in prior studies examining a similar approach for the treatment of the related condition, trigger finger. Two separate studies compared the efficacy of intra-sheath vs extra-sheath steroid injections in this condition and found that extra-sheath injections were as effective as intra-sheath injections in the treatment of trigger finger(7,8). These studies lay the groundwork for this approach in DeQuervain's, however, no clinical trials comparing the efficacy and safety of intra-sheath versus extra-sheath steroid injections for the treatment of DeQuervain's tenosynovitis have been reported to date.

Study Timelines:

Participants will be screened and enrolled at their clinic visit at UC Davis Health Center. Once the patient has qualified for the study, they will undergo either the intra-sheath or extra-sheath steroid injection. Patient's will return for follow-up appointments at 6 weeks, 6 months and 1 year post injection. We estimate a 2.5 year enrollment period, followed by a six-month data review period.

Power analysis:

This study is designed to determine whether extra-sheath steroid injection is similarly effective (i.e., noninferior) to intra-sheath steroid injection at improving pain. The study sample size will be determined on the basis of an expected standard deviation of 14mm in the primary outcome of pain improvement and a non-inferiority limit of 14mm. This expected standard deviation was derived from previous trials that examined the efficacy of steroid injections for DeQuervain's tenosynovitis (1). The non-inferiority boundary of 14mm was selected based on a previously calculated minimum clinically important difference (MCID) on the VAS pain scale of 14mm(5). The primary outcome of interest is the difference between pre-injection and 6 weeks post-injection VAS scores in each group. Assuming a non-inferiority test for the difference between two means, we find that a group sample size of 13 in the intra-sheath and 13 in extra-sheath steroid injection group achieves 80% power to detect non-inferiority using a one-sided two-sample t-test. The margin of non-inferiority is 14mm. The true difference between the means is assumed to be 0. The significance level (alpha) of the test is 0.050. The expected standard deviation is 14mm.

To ensure we have an adequate number of patients to achieve significance for secondary study endpoint analysis and allowing for a dropout rate of 15% we plan to enroll 80 patients.

Procedures Involved:

The trial will be a double blinded randomized controlled trial with half of the subjects randomized to receive intra-sheath injection and the other half receiving extra sheath injection. After signing consent, the inclusion and exclusion criteria will be reviewed. Eligible subjects will be enrolled and randomized into the study. The consenting researcher will use a digital Randomizer application ("Randomizer", available on all smart phones) to assign the individual to either intra-sheath injection group or extra sheath injection group. After being randomized, the study arm will be recorded at subject source document and Enrollment Log. The signed consent will be scanned into the patient's electronic medical record. The hard copy consents will be stored securely.

In both groups the injection will be ultrasound-guided and the injection solution will be composed of 1ml of 1% lidocaine and 1ml (20mg) of dexamethasone.

Patients randomized to the intra-sheath injection group will have all fluid injected directly into the APL/EPB sheath. In this group of patients, if subcompartments are found upon ultrasound inspection half of the solution will be deposited into the APL sheath and the other half will be deposited into the EPB subsheath, as previously described(5).

In patients randomized to the extra-sheath injection group, the injection will be given surrounding the sheath.

In both groups, pain will be measured using the visual analog scale (VAS) and symptoms/disability will be measured using the shortened Disabilities of the Arm, Shoulder and Hand Questionnaire (quickDASH).

The DASH questionnaire is a 30 item test commonly administered to patients with upper extremity disorders that allows them to self-assess the level of disability/symptoms associated with their disorder(10). The shortened version (quickDASH) reduces the number of test questions from 30 to 11. There are 5 answer choices for each item of the test and 10 out of the 11 questions must be answered for the test to be considered valid. Based on the patients answers to the questions, a score between 0 (no disability) and 100 (severe disability) will be calculated.

All results, including which group the patient was randomized to will be recorded and input into the appropriate spreadsheet.