An exploratory study to perfect the Letournel classification of acetabular fractures

Abstract

Objectives To put forward the modified Letournel classification of acetabular fractures, and evaluate the guiding role of the modified Letournel classification in clinical work. Methods A retrospective study of 170 patients (178 sides) with acetabular fractures treated at Nanfang Hospital between January 2006 and August 2018 was performed. Among them 129 cases were males and 41 were females. The average age was 40.2±14.2 years (range, 14-82 years). According to the Letournel classification, unclassifiable/atypical acetabular fractures were found out with plain X-ray and plain CT scan and three-dimensional CT, and then their unclassifiable reasons were analyzed. Based on anatomical landmarks, clear boundaries of acetabular walls were defined on the 3D printed pelvic model. The structure of each column is a trihedron. The wall’s fracture and column’s fracture were distinguished using a theory that the wall’s fracture involved two surfaces of column with interruption of continuity and column’s fracture involved three. When column’s fracture associated with wall’s fracture, lowercase a, p and q were used representing comminuted areas of corresponding anterior and posterior wall, quadrilateral plate respectively. When column’s fracture didn’t associates with wall’s fracture, it is marked with number 0. Finally, all fractures were classified according to the modified Letournel classification. The relationship between fracture type and surgical approach was analyzed. Results There was 51.7% (92 sides) of acetabular fractures that couldn’t be classified by the Letournel classification. Incomplete fracture lines (49 sides, 53.3%), comminuted fractures (28 sides, 30.4%), both of them (15 sides, 16.3%) were their unclassifiable reasons. There were 8 types in the modified Letournel classification, including posterior wall fracture, posterior column fracture, anterior wall fracture, anterior column fracture, transverse fracture, T-shaped fracture, anterior column+posterior hemitransverse fracture, and both columns fracture. Posterior column+posterior wall fracture, transverse+posterior wall fracture had respectively become a form of posterior column fracture and of transverse fracture. According to the modified Letournel classification, the reclassification rate of 178 side fractures was 100%, which was significantly higher than 48.3% (86/178) of the traditional Letournel classification, and the difference was statistically significant (χ2=124.06, P< 0.001) . 100% of posterior wall fracture and 80.00% of posterior column fracture were treated by posterior approach. 100% of anterior column fracture and 73.68% of both columns fracture were treated by anterior approach. Conclusion All acetabular fractures can be classified by the modified Letournel classification. The orientation of the comminuted walls reflects in part severity of the injury, better helps orthopaedic surgeons understand the morphology of acetabular fractures and select appropriate surgical approach. Key words: Acetabulum; Fractures, bone; Classification