Detailed morphometric analysis of the pronator quadratus muscle: a cadaveric study

The pronator quadratus (PQ) is a flat muscle located in the distal forearm, between the radius and ulna, primarily responsible for forearm pronation. Given its frequent involvement in volar surgical approaches to the distal radius and its use in reconstructive procedures, such as flap transfers, a detailed understanding of its anatomy is clinically significant. This study aims to analyze the morphometric properties of the PQ, determine its distances from key osseous landmarks, and assess gender-based anatomical differences to inform surgical planning and minimize iatrogenic complications.

A total of 27 formalin-fixed cadaveric forearms (18 male, 9 female), with no prior surgical history, were dissected. The forearms were positioned in supination, and anatomical landmarks were marked with needles. ImageJ software was used to measure the PQ's surface area and the anterior surface area of ​​the radius distal to the pronator quadratus, devoid of muscle fibers (muscle-free radius area-MRA). Morphometric measurements of the PQ muscle were also performed. In addition, the anatomical relationships of the PQ muscle and the anterior interosseous nerve (AIN) with adjacent bony landmarks were evaluated. Right-left and male-female comparisons were conducted.

The PQ was present in all specimens, originating from the medial border of the distal third of the ulna and inserting into the distal third of the radius. It was innervated by the anterior interosseous nerve (AIN) and primarily supplied by the anterior interosseous artery (AIA), with additional branches from the radial artery in six cases. Gender comparisons showed that PQ's proximal and distal widths were greater in men, but muscle area showed no significant difference. However, the muscle-free radius area on the anterior radius was significantly larger in males. The AIN was positioned farther from the radius and ulna in men. No right-left differences were observed for AIN, though the PQ's distance to the lunate fossa was longer on the right side.

This study could provide valuable biometric data for surgical procedures involving the distal forearm by detailing the anatomy of the PQ. In particular, measurements based on fixed bone landmarks may serve as a guide for determining reliable areas for plate and screw placement in distal radius fractures. In addition, awareness of possible anatomical variations in this region may contribute to safer and more individualized surgical planning.