Anatomical variations of the semilunar notch in elbow dislocations.
The anatomical relations of the semilunar notch of the ulna were studied in radiographs, taken in a strict lateral view, from 100 patients with elbow dislocations. The results were compared with those from a control group of 150 patients without dislocation or other radiographic pathology. We found that the coronoid process and an angle (a) formed between the axis of the ulna and a line going through the tip of the coronoid process and the tip of the olecranon were significantly smaller than those in the control group (P = 0.02). The central angle of the semilunar notch was significantly larger in the dislocation group than in the control group (P = 0.009). The smaller angle (a) and larger central angle in the dislocation group are a result of a lower coronoid process, but they are also due to the prominent tip of the olecranon. The results suggest that the dislocation mechanism is partly a hyperextension, with the tip of the olecranon as the pivot point.
D004198:Disease Susceptibility; D004551:Elbow Joint / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D004204:Joint Dislocations / Q000000981:diagnostic imaging* / Q000209:etiology; D011859:Radiography; D014457:Ulna / Q000000981:diagnostic imaging / Q000473:pathology*; D000092464:Elbow Injuries