Anomalous Flexor Carpi Radialis Anatomy During Volar Distal Radius Approach: Two Case Reports

Volar locking plates become the standard treatment for distal radius fractures and are mostly applied through volar approaches that rely on the flexor carpi radialis (FCR) as a superficial landmark. Although usually straightforward, anomalous flexor musculature may complicate exposure, misdirect dissection and increase the risk of iatrogenic neurovascular injury. We report two rare anatomical variants encountered during open reduction and internal fixation: FCR brevis (FCRB) associated with anomalous insertion of the pronator quadratus, and complete agenesis of the FCR. Both substantially altered the expected surgical anatomy. The FCRB obscured the typical superficial interval and was associated with ulnar displacement of the pronator quadratus on deeper dissection. In the second case, the absence of the FCR eliminated a key landmark, with the palmaris longus becoming the most radial tendon, increasing the risk of inadvertent ulnar dissection towards the median nerve and its palmar cutaneous branch. Recognition of these variants is essential to ensure safe volar exposure and avoid neurovascular injury. Level of Evidence: Level V (Therapeutic).