Safe Window for the Volar Needle Approach to Pronator Quadratus using Ultrasonography

Publication date: Available online 26 May 2017
Source:Archives of Physical Medicine and Rehabilitation
Author(s): Seok Jun Lee, Ki Hoon Kim, In Yae Cheong, ByungKyu Park, Dong Hwee Kim
ObjectiveTo investigate PQ anatomy and determine the proper volar needle insertion point based on landmarks, the tip of the ulnar styloid (U line), and the ulnar margin of the palmaris longus tendon (uPL) using ultrasonography.DesignDescriptive study.SettingDepartment of Physical Medicine & Rehabilitation, Korea University, Seoul, KoreaSubjectsTwenty-five healthy subjects (13 men, 12 women; 50 forearms)InterventionsUltrasonographyMain outcome measuresThe proximal and distal volar surface points of origin (O_prox and O_dist), the proximal and distal insertion sites (I_prox and I_dist), and the center of the PQ (PQ_M) were determined. The distance of each of the PQ surface indices from the U line was measured, and the probe was applied at the level of PQ_M parallel to the U line. The relative distances from the vertical surface points of the median nerve and ulnar artery to the uPL were measured.ResultsThe mean age and body mass index were 32.7±10.4 years and 21.98±2.83 kgm-2. The PQ_M was located at a mean 2.63±0.35 cm proximal from the U line (men 2.79±0.37 cm and women 2.45±0.21 cm, p<0.05). The mean safety window for the volar approach was 0.72±1.8 cm toward the radial side and 1.51±0.30 cm toward the ulnar side from the uPL. The PQ was a mean 1.30±0.19 cm deep from the skin and had a mean thickness of 1.19±0.24 cm at the level of the PQ_M. The distance between U line and proximal edge of PQ, as well as the PQ thickness, was greater in men than in women.ConclusionsThe volar approach for needle electromyographic examination of the PQ can be performed precisely and safely.



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