Morphological analysis of coronoid process fracture in terrible triad of elbow based on Adams classification / 中华创伤杂志

ABSTRACT

Objective:To explore the morphology of coronoid process fracture in terrible triad injury based on Adams classification.Methods:A retrospective cross-sectional study was used to analyze the three-dimensional CT data of 51 patients with terrible trind injury treated at First Affiliated Hospital of Fujian Medical University from January 2013 to August 2021, including 33 males and 18 females, aged 18-88 years [(44.7±12.0)years]. The model of ulna coronoid process fracture was established by three-dimensional CT reconstruction technology and was classified according to Adams coronoid process fracture classification. Type I was the coronoid process tip fracture, type II the coronoid process transverse fracture, type III the base fracture of the coronoid process, type IV anterior internal fracture the anteromedial oblique fracture of the coronoid process, and type IV anterior external fracture the anterolateral oblique fracture of the coronoid process. According to the characteristics of the coronoid fracture fragment, type IV anterior external fracture was divided into two subtypes α subtype involving the coronoid tip and β subtype without involving the coronoid tip. Then, the proportion, height, surface area and volume of different types of coronoid fractures were measured. The proportion, height, surface area and volume of fracture fragments of two subtypes of type IV anterior external fracture were measured, as well as the area of ulnar trochlear joint, area of trochlear joint of ulnar fracture fragment, proportion of the area of trochlear joint affected by the ulnar fragment, area of proximal radioulnar joint, area of proximal radioulnar joint of ulnar fracture fragment and proportion of the area of proximal radioulnar joint affected by the ulnar fragment.Results:Among the patients with terrible triad injury, the ulnar coronoid process fracture was Adams type I in 17 patients (33%), type II in 4 (8%), type III in 4 (8%), type IV anterior internal fracture in 4 (8%) and type IV anterior external fracture in 22 (43%). The height of fracture fragment of type I, type II, type III, type IV anterior internal fracture and type IV anterior external fracture was (3.7±1.9)mm, (10.8±1.1)mm, (14.4±1.2)mm, (5.2±2.4)mm and (6.7±2.6)mm, respectively; the surface area was 63.7(21.4, 221.0)mm 2, 1 086.8(606.8, 1 434.2)mm 2, 1 658.8(1 335.6, 1 695.4)mm 2, 437.3(185.6, 437.3)mm 2 and 511.8(198.8, 646.5)mm 2, respectively; the volume was 46.3(21.4, 180.5)mm 3, 938.7(629.8, 1 011.3)mm 3, 1 797.4(1 520.2, 1 903.7)mm 3, 429.3(138.1, 992.4)mm 3 and 461.9(144.9, 707.1)mm 3, respectively. There were significant differences in the height, surface area and volume of coronoid process fracture with different Adams classification (all P<0.01). Among 22 patients with type IV anterior external fracture, 12 patients were with α subtype and 10 with β subtype. The fracture height of α and β subtypes was (8.6±2.6)mm and (5.0±2.4)mm, respectively; the surface area was 633.2 (530.3, 727.4)mm 2 and 181.4 (136.7, 450.3)mm 2, respectively; the volume was 692.8 (477.6, 778.0)mm 3 and 128.0 (74.2, 405.1)mm 3, respectively. The height, surface area and volume of fracture fragment were significantly different between the two subtypes (all P<0.01). The area of ulnar trochlear joint of α and β subtypes were 901.4(755.1, 1 060.6)mm 2 and 835.2(767.7,909.3)mm 2, respectively; the area of trochlear joint of α and β subtype fragment was 104.1(79.4, 139.9)mm 2 and 38.8(21.3, 58.1)mm 2, respectively; the proportion of the area of trochlear joint affected by α and β subtype fragment was 0.12(0.09, 0.15) and 0.05(0.03, 0.07), respectively. There was no significant difference between α and β subtypes in the area of trochlear joint of ulna ( P>0.05), but the area of trochlear joint of α subtype fragment and proportion of the area of trochlear joint affected by α subtype fragment were higher than those of β subtype fragment (all P<0.01). The area of proxima radioulnar joint of α and β subtypes was 147.9(111.7,164.2)mm 2 and 137.0(118.7,166.7)mm 2, respectively; the area of proximal radioulnar joint of α and β subtypes fragment was 17.7(13.4, 52.2)mm 2 and 6.1(2.6, 20.0)mm 2, respectively; the proportion of the area of proximal radioulnar joint affected by α and β subtypes fragment was 0.12(0.10, 0.35) and 0.05(0.03, 0.15), respectively. There were no significant differences between the two subtypes in proximal radioulnar joint damage (all P>0.05). Conclusions:Adams type IV fracture of the coronoid process of the ulna occupies a large proportion in terrible triad injury, and the type IV anterior external fracture is the main type containing two subtypes with differences in fragment size and shape. However, the injuries to the proximal radioulnar joint surface are similar for the two subtypes, so the injuries of type IV anterior external fracture with different sizes to the proximal radioulnar joint surface should not be neglected in clinical treatment.