The arcuate fracture: A descriptive radiographic study.

Purpose: To assess plain radiographic morphology of arcuate fractures in order to identify patterns and help shape treatment algorithm for proximal fibula fracture.

Methods: A search of radiographic reports at a level 1 trauma center from 2014 to 2016 using MONTAGE search software for the phrases "arcuate fracture", "fibular head avulsion", or "fibular head fracture" was conducted. Descriptive measurements were obtained including dimensions of the fragment, the displacement of the fragment from its anatomic position, and the orientation of the primary fracture line relative to the axis of the fibular diaphysis in both the sagittal and coronal plane. After review of the measurements and radiographs, fracture patterns were assessed based off previous knowledge previous knowledge of posterior lateral corner (PLC) anatomy.

Results: Radiographic reports of 48 knees (48 patients) met inclusion criteria. The distance of fractures from the proximal aspect of the fibula averaged 9.25 ± 5.53 mm on AP radiographs, and 9.42 ± 4.89 mm on lateral radiographs. The medial-to-lateral width of the proximal fragment averaged 20.09 ± 7.94 mm on AP radiographs, while the anterior-to-posterior width measured on lateral radiographs averaged 17.53 ± 8.48 mm. Orientation of the primary fracture line was calculated at an average of 23.04 ± 14.95° from the perpendicular on the AP view, and 21.55 ± 17.44° from the perpendicular on the lateral. Maximal displacement at the primary fracture line on the AP view was 4.95 ± 8.49 mm). Maximal displacement on the lateral measured 3.98 ± 7.01 mm. Recurring fracture patterns were identified and described. Assessment revealed 11 (22.9%) pattern 1 fractures, six (12.5%) pattern 2 fractures, 31 (64.58%) pattern 3 fractures, possibly correlating with anatomical features and fracture mechanism.

Conclusions: These measurements and recurring patterns in our study shows the heterogeneity of the size and displacement of these fracture fragments and demonstrates the need for further studies in order to create an anatomic descriptive classification for arcuate fractures, which could be used for clinically for treatment.