Precision of Ultrasound-Guided versus Anatomical Palpation-Guided Needle Placement of the Ulnar Nerve at the Cubital Tunnel: A Cadaveric Study

Percutaneous electrical stimulation has been performed for years with only the assistance of anatomical landmarks. The development of real-time ultrasonography guidance has improved the precision and safety of these percutaneous interventions. Despite ultrasound-guided and palpation-guided procedures being performed routinely for targeting nerve tissues in the upper extremity, the precision and safety of these techniques are unknown. The aim of this cadaveric study was to determine and compare the precision and safety of ultrasound-guided versus palpation-guided needling procedure with and without the handpiece of the ulnar nerve on a cadaveric model. Five physical therapists performed a series of 20 needle insertion tasks each (n = 100), 10 palpation-guided (n = 50) and 10 ultrasound-guided (n = 50) on cryopreserved specimens. The purpose of the procedure was to place the needle in proximity to the ulnar nerve at the cubital tunnel. The distance to target, time performance, accurate rate, number of passes, and unintentional puncture of surrounding structures were compared. The ultrasound-guided procedure was associated with higher accuracy (66% vs. 96%), lower distance from needle to the target (0.48 ± 1.37 vs. 2.01 ± 2.41 mm), and a lower frequency of perineurium puncture (0% vs. 20%) when compared with the palpation-guided procedure. However, the ultrasound-guided procedure required more time (38.33 ± 23.19 vs. 24.57 ± 17.84 s) than the palpation-guided procedure (all, p < 0.001). Our results support the assumption that ultrasound guidance improves the accuracy of needling procedures on the ulnar nerve at the cubital tunnel when compared with palpation guidance.