Hybrid-J shape needle in ultrasound-guided looped thread carpal tunnel release: a cadaveric study on safety and efficacy.

BACKGROUND

Carpal tunnel syndrome (CTS) is the most prevalent peripheral nerve entrapment disorder, often requiring surgical intervention. While Ultrasound-guided Looped Thread Carpal Tunnel Release (LTCTR) offers a minimally invasive alternative to carpal tunnel release, its implementation faces limitations due to insufficient specialized instruments. This cadaveric study assesses the Hybrid-J Shape Needle (HJSN), a blunt-tip, J-shaped device designed to improve safety in LTCTR procedures.

METHODS

Twenty fresh-frozen cadaveric specimens (40 wrists) were included. Ten junior surgeons were randomly assigned two cadavers, performing LTCTR with normal cannula needle (NCN) on one wrist of the same cadaver, followed by HJSN on the contralateral wrist. Intraoperative structural damage such as nerve, blood vessel and tendon were assessed by blinded observer and anatomist. Post-procedural dissection confirmed transverse carpal ligament (TCL) transection completeness. Surgeons evaluated usability, adoption intent, and likelihood of recommendation using 5-point Likert scales. Biomechanical testing assessed force thresholds required for tendon and nerve penetration. Statistical analysis included Mann-Whitney U-test, Student's t-test, and Chi-square tests.

RESULTS

HJSN reduced operative time compared to NCN (25.10 ± 6.50 vs. 31.49 ± 6.36 min, p < 0.01) and achieved 100% complete TCL transection (20/20 vs. 16/20 for NCN, p = 0.035). NCN resulted in 3 median nerve (MN) injuries, 2 ulnar artery injuries, 2 superficial palmar arch (SPA) injuries, and 2 tendon injuries, whereas HJSN caused only 1 SPA injury (OR = 10.23, 95% CI: 1.12-93.34, p = 0.02). Biomechanical testing demonstrated HJSN required higher force to penetrate tendons (27.07 ± 2.43 N vs. 9.89 ± 2.53 N, p < 0.01) and nerves (25.75 ± 3.26 N vs. 10.72 ± 2.61 N, p < 0.01). Surgeons reported stronger preference for HJSN (3.60 ± 1.07 vs. 2.40 ± 1.07, p = 0.03) and recommendation (3.80 ± 1.23 vs. 2.20 ± 1.03, p < 0.01), though usability scores were comparable (4.10 ± 1.10 vs. 3.50 ± 1.18, p = 0.22).

CONCLUSION

HJSN's unique blunt-tip and J-shaped design improves LTCTR safety by reducing iatrogenic injuries and ensuring complete TCL release. Its biomechanical superiority and surgeon preference support clinical translation, especially for trainees. While cadaveric data are encouraging, clinical trials are needed to confirm efficacy.