Ulnar Nutrient Foramen Morphology and Minimizing Screw Damage in Ulnar Fractures

The aim of this study is providing an in-depth investigation of the morphological and morphometric characteristics of the nutrient foramen (NF) to minimize the damaging of the NF during fixation of ulnar fractures. This study was performed by using a sample of 110 dry ulnae (47 right, 63 left). The ulnar length (UL), distance between the NF and the most proximal point of olecranon (NFO), as well the distance between the NF and interosseous border (NFIB) were taken under measurement. The number, location, direction, position, and size of NF was evaluated. Also, the foraminal index (FI) was calculated. In addition, forearm fracture was created experimentally on a cadaver belonging to a 73-year-old Turkish female in our department, and ulnar open reduction internal fixation was performed. After the removal of the plate and screws, the effect of plate fixation on the NF was evaluated and examined for further treatment decisions. The mean UL, NFO, NFIB and FI were measured to be 244.16 ± 17.65 mm, 93.76 ± 18.11 mm, 8.23 ± 3.67 mm, and 38.29 ± 6.45%, respectively. In general, 1 NF was detected on the ulnae, which was located anterior surface, directed upwards, on 2/5 zone and smaller than 22-gauge size. The distances between the most proximal first, second and third screws and interosseous border were measured to be 4.39 mm, 6.20 mm, and 6.56 mm, respectively. The screws were found not to have damaged the NF on fractured ulna of cadaver. According to our dry bone and cadaveric results, being knowledgeable about the morphologic and morphometric characteristics of NF is important in screwing the plate, which should be done to the distal parts of shaft if possible and near the anterior border of ulna for minimizing the damage to the nutrient foramen in order to preserve the blood supply of the bone.