A Cadaveric Study Examining the Accuracy of Wireless Hand-Held Guided Ultrasound Injections Versus Blind Injections in the Flexor Tendon Sheath

Abstract

Purpose: Hand-held ultrasound (HHUS) is gaining popularity among clinicians. Although its use for procedural guidance could have several advantages in hand surgery, other surgeons may wonder about its added benefits. This cadaveric study aimed to examine the hypothesis of increased accuracy of wireless HHUS-guided injections versus that of blind injections into the flexor sheath.

Methods: Our series included 20 fresh cadaveric hands with 80 fingers randomly assigned to 2 groups. In group A, 10 hands were randomly assigned to receive a landmark injection and then received a blinded injection to the flexor tendon sheath (FTS). In group B, 10 hands were blinded in the same manner and received an ultrasound-guided injection with HHUS. Methylene blue was injected, and anatomic dissection was performed to evaluate the injection accuracy based on the dye's filling pattern in the FTS as stage I (no filling), stage II (<50% filling), and stage III (>50% filling). Statistical analysis was performed, and P <.05 indicated a significant difference.

Results: One finger was excluded because of severe Dupuytren contracture. In group A, 39 blind injections of the FTS were performed, with 82% (32/39) fingers achieving stage III filling. In group B, 40 ultrasound-guided FTS injections were performed, with 90% (36/40) of fingers achieving stage III filing. Our study did not reveal any superiority in accuracy when ultrasound guidance was used (P = .35).

Conclusions: Hand-held ultrasound-guided FTS injections were not more accurate than blind injections performed by an experienced hand surgeon. These findings suggest that blind injections can be used as routine practice when performed by experienced operators to treat trigger finger. However, the use of HHUS may offer other advantages in hand surgery practice.

Clinical relevance: Ultimately, choosing to perform HHUS-guided injection versus blind injection to treat trigger finger depends on the surgeon's experience and preference for a particular technique.

Keywords: Blinded; Flexor tendon sheath; Hand-held ultrasound; Injection; Ultrasound-guided.

Figure 1

Sonographically guided injection into the right middle finger of a cadaver.

Figure 2

Axial views of the FTS before and after injection. A Preinjection view. B Intrasheath injection view showing the diffusion pattern within the FTS indicated by the white polygon. The tip of the needle is represented by the white asterisk. FDS, flexor digitorum superficialis; FDP, flexor digitorum profundus.

Figure 3

Injection accuracy based on the dye’s filling pattern of FTS classified as stage I (no filling), stage II (<50% filling), and stage III (>50% filling).