Study on the fracture morphology and imaging of distal radioulnar ligament of type C distal radius fracture

Objective To provide reference data for clinical and biomechanical research through drawing the fracture morphology of type C distal radius fracture and the length of distal radioulnar ligament by fracture mapping technology. Methods From January 2018 to December 2018, 59 cases of OTA/AO 23 C type distal radius fractures were treated in our hospital. Thirty wrist joints of 15 volunteers were used as healthy control group. After thin-layer CT scanning of the wrist joint, the three-dimensional reconstruction was performed by importing the Mimics medical software. The fracture line of the distal radius was introduced into the template after standardization, and the shape of the fracture line was obtained after fitting. The length of the distal radioulnar ligament was obtained by measuring the distance between the sigmoid notch and the base and recess of styloid process of ulna. Results On the radiocarpal joint surface, the fracture line was mainly concentrated around the lunate fossa demonstrated as cross; on the volar side, the fracture line was mainly concentrated around the watery flow line; on the dorsal side, the fracture line was concentrated around Lister's tubercle and scattered; in the area of sigmoid notch, the fracture line was concentrated in the middle 1/3 and dorsal 1/3 of sigmoid notch; in the area of styloid process of radius, it was seen that the styloid process of radius was relatively complete, and the fracture line was distributed under the styloid process of radius. There was no significant difference in the length of the four groups of ligaments, i.e. the volar superficial distal radioulnar ligament, the dorsal superficial distal radioulnar ligament, the volar deep distal radioulnar ligament and the dorsal deep distal radioulnar ligament among the subtypes (C1, C2, C3) of type C distal radius fracture (P>0.05); there was no significant difference between the groups and the healthy control group (n=30, P>0.05). When the fracture line was located in the volar 1/3 and dorsal 1/3 of the sigmoid notch, the length of the palmar superficial distal radioulnar ligament, the dorsal superficial distal radioulnar ligament and the dorsal deep distal radioulnar ligament were significantly different from that of the healthy control group (n=30, P<0.05). Conclusion The fracture pattern of type C distal radius can be visualized by fracture mapping technology. On the radiocarpal joint surface, the fracture line is concentrated around the lunate fossa; in the joint area of sigmoid notch, the fracture line is more concentrated in the middle 1/3 and the dorsal 1/3 of sigmoid notch. When the fracture line is distributed in the volar 1/3 and the dorsal 1/3 of sigmoid notch, it may lead to the risk of distal radioulnar ligament injury. Key words: Radius fractures; Biomechanics; Fracture mapping; Distal radioulnar ligament