Three-dimensional quantitative study and functional outcome analysis of coronoid fracture in different elbow injury patterns.

Abstract

Coronoid 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 three-dimensional computed tomography. All patients with coronoid fractures surgically treated at our hospital between January and December 2017 were categorized into 3 groups according to elbow injury pattern: posterolateral rotational instability (PLRI), varus posteromedial rotational instability (VPMRI), and olecranon fracture-dislocation (OFD). 3D models were reconstructed using Mimics 17.0, and the total volume and number of coronoid fragments 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 range of motion, visual analog scale, Mayo Elbow Performance Score, complications and reoperations were recorded. The 92 patients enrolled had an average age of 42 ± 15 years and a male-to-female ratio of 66:26. The median total volume in PLRI patients was less than that in VPMRI patients [431 (132, 818) mm³ vs. 1125 (746, 1421) mm³, adjusted P < .001] and OFD patients [431 (132, 818) mm³ vs. 2565 (381, 4076) mm³, adjusted P = .001]. The median number of coronoid fragments in PLRI patients was also less than that in VPMRI patients [1 (1, 2) vs. 2 (1, 3), adjusted P = .043]. Most of the P_CFL-Rs (79%) were located around the volar edge of the lesser sigmoid notch. Compared with that of PLRI, the P_CFL-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 = .001] and the median Mayo Elbow Performance Score [85 (68, 95), P = .038] of patients with OFD were significantly less than those of patients with the other 2 patterns. The incidence of elbow stiffness (56%, 5/9, P = .001) and implant-related irritation (44%, 4/9, P < .001) in the OFD group was significantly higher than that in the other 2 groups. Coronoid 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.