Three-Dimensional Quantitative Study and Functional Outcome Analysis of Coronoid Fracture in Different Elbow Injury Patterns

Abstract

BackgroundCoronoid fractures are often part of a complex fracture-dislocation of the elbow. For an optimum prognosis, it is important to understand the characteristics of coronoid fractures in different elbow injury patterns. Significant differences in these characteristics have been observed in various studies, but these previous studies have suffered from limitations, such as insufficient quantification and unknown prognostic differences among different injury patterns. Therefore, we aimed to quantitatively analyze coronoid fracture characteristics and functional outcomes in different elbow injury patterns using 3D-CT. MethodsAll patients with coronoid fractures surgically treated at our hospital between January and December 2017 were categorized into three groups according to elbow injury pattern: PLRI, VPMRI and OFD. 3D models were reconstructed using Mimics 17.0, and the total volume (TV) and number of coronoid fragments (NCF) were measured. The coronoid process edge was classified into different anatomical regions, and each region was assigned a number to quantify the distribution of fracture lines. At the last follow-up, the ROM, VAS, MEPS, complications and reoperations were recorded. ResultsThe ninety-two patients enrolled had an average age of 42±15 years and a male-to-female ratio of 66:26. The median TV in PLRI patients was less than that in VPMRI patients [431 (132, 818)mm3 vs. 1125 (746,1421)mm3,adjusted P<0.001] and OFD patients [431 (132, 818) mm3 vs. 2565 (381, 4076)mm3, adjusted P =0.001]. The median NCF in PLRI patients was also less than that in VPMRI patients [1 (1, 2) vs. 2 (1, 3), adjusted P=0.043]. Most of the PCFL-Rs (79%) were located around the volar edge of the lesser sigmoid notch. Compared with that of PLRI, the PCFL-Us of the VPMRI and OFD tended to be located on the more ulnodorsal side of the coronoid process edge. The median ROM [110 (90, 133), P=0.001] and the median MEPS [85 (68, 95), P=0.038] of patients with OFD were significantly less than those of patients with the other two patterns. The incidence of elbow stiffness (56%, 5/9, P=0.001) and implant-related irritation (44%, 4/9, P<0.001) in the OFD group was significantly higher than that in the other two groups. ConclusionCoronoid fractures differ significantly in fragment volume, comminution severity and fracture line distribution among different elbow injury patterns. OFD has the worst functional outcomes among complex elbow injury patterns.