Unclassified acetabular fractures: Do they really exist?

Although Letournel classification is considered the corner stone for classifying acetabular fractures, however, it might not be perfectly inclusive. Unclassified fractures were reported by many authors. The aim of this case series is to report the incidence of unclassified acetabular fractures and description of these rare patterns and why they are considered unclassified acetabular fractures.

This is a retrospective consecutive case series. In the period between 1st January 2016 and 31st December 2017, 235 patients with 236 acetabular fractures were identified from our hospital records. Classification of the acetabular fractures according to Letournel was done by two surgeons. Any discrepancy in the classification between the two surgeons was resolved by the senior author. Before considering the fracture unclassifiable, all fractures were reviewed again by the two surgeon and the senior author.

In the period between 1st January 2016 and 31st December 2017, 235 patients with 236 acetabular fractures were included in our study. Twenty-two fractures (9.3%) did not fit into any of the fracture types according to Letournel Classification as follows: 1 case (4.5%) was pure Quadrilateral plate fracture, 1 case (4.5%) was labral avulsion with tiny posterior wall rim, 1 case (4.5%) was pure articular impaction, 1 case (4.5%) was both columns fracture with posterior wall, 4 cases (18.2%) were anterior column and quadrilateral plate fracture, and 14 cases (63.8%) were T with posterior wall.

Several acetabular fracture pattern could be considered unclassified fractures. These unique patterns may require special approaches or special fixation methods. However, this is not a call for a new classification for acetabular classification to include these new types. Subclassification or adding modifiers to Letournel classification can do the job.