A cadaveric study of radial and ulnar bowing in the sagittal and coronal planes

Background This study provides a comprehensive, full-length assessment of radial and ulnar bowing in anteroposterior (AP) and sagittal planes. Methods Radial and ulnar AP and lateral bowing were assessed using orthogonal digital photographs of 211 randomly selected cadaveric bilateral forearms (422 radius, 422 ulna bones) from a well-preserved osteologic collection. Results In the radial AP plane, an apex-radial bow was present at a mean of 58% of bone length (slightly distal to midpoint), with a mean depth of 1.3 cm. In the radial lateral plane, an apex-dorsal bow occurred at a mean of 45% of bone length, with a mean depth of 0.8 cm. In the ulnar AP plane, apex-radial bow occurred at a mean of 32% of bone length with a mean depth of 1.0 cm. In the ulnar lateral plane, the majority of specimens (81%) had an apex-dorsal bow, whereas 19% had a reverse (apex-volar) bow. Lateral ulnar bow was located at a mean of 33% of bone length with a mean depth of 2.0 cm, with 36% of specimens possessing a lateral bow located at 35% or more distal along the ulna. Side-to-side differences for bow location and depth were less than 2% of bone length. Conclusions Ulnar lateral bow was found to be more distal than in previously published works, which analyzed only the proximal ulna, and this study describes a reverse ulnar bow in 19% of specimens. This demonstrates lateral ulnar morphology to be more variable than previously defined with minimal side-to-side variability, which are important considerations for fracture fixation and elbow arthroplasty.