Posterior acetabular arc angle of unstable posterior hip fracture–dislocation

Abstract

Purpose Posterior hip fracture-dislocation needs stability evaluation. A previous study in the normal acetabulum has shown that the coronal posterior acetabular arc angle (PAAA) could be used to assess an unstable posterior hip fracture. Our study was designed to assess PAAA of unstable posterior hip fracture-dislocation and whether posterior acetabular wall fracture involves the superior acetabular dome. Methods Using coronal computed tomography (CT) of the acetabulum and 3D reconstruction of the lateral pelvis, we measured coronal, vertical PAAA and posterior acetabular wall depth of 21 unstable posterior hip fracture-dislocations and of 50 % normal contralateral acetabula. Posterior acetabular wall fracture was assessed to determine whether the fracture involved the superior acetabular dome and then defined as a high or low wall fracture using vertical PAAA in reference to the centroacetabulo-greater sciatic notch line. Results The coronal PAAA of unstable posterior hip fracturedislocations and of 50 % of the posterior acetabular wall of normal the contralateral acetabulum were 54.48°(9.09°) and 57.43°(5.88°) and corresponded to 15.06 (4.39) and 15.61

Correlation of stability and complications measurements in traumatic hip dislocation cases associated with posterior wall acetabular fracture

“…Preoperative assessment of posterior hip fracture dislocations is important in terms of planning treatment but difficult due to the complicated anatomicalstructure (9). After these injuries there are many factors affecting outcomes (14,15).…”

“…In our cases, the acetabular defect percentage was determined to be minimum 39% and all hips were unstable and were patients admitted to the emergency service with hip fracture dislocations. Harnroongroj et al reported that in addition to this assessment, coronal PAAA values were beneficial to predict stability without requiring assessment of the normal hip (8,9). Investigations by Harnroongroj et al found coronal PAAA values of more than 77 degrees instable hips, while hips with less than 50 degrees were unstable (8).…”

“…Another method determining posterior instability risk is assessment of the posterior acetabular arc angle (PAAA). This angle is assessed vertically in a study and assessed coronally in another study (8,9). Coronal PAAA was determined as a reliable method to determine posterior acetabular fracture dislocation risk without requiring hip evaluation.…”

Acetabular roof arc angles and anatomic biomechanical superior acetabular weight bearing area

“…At this level, the fracture included part of posterior acetabular wall and position of femoral head is high degrees of flexion, the fracture mostly creates posterior acetabular wall fracture and dislocation hip. 4 62° of posterior acetabular roof arc angle of Chuckpaiwong and Harnroongroj included posterior end of anatomic superior articular cartilage of acetabulum because the transverse osteotomy started from greater sciatic notch passing through juxtatectal area of acetabulum and excluding posterior acetabular wall by the osteotomy. Moreover, the 62° posterior acetabular roof arc angle had confirmed no involvement of posterior portion of the ABSAWBA in our study.…”

“…Acetabular fracture involving superior weight bearing area shows significantly poor results 12. Moreover, stability of the hip depends on adequate acetabular coverage of the femoral head 34. Roof arc angle is a method to evaluate adequate acetabular coverage and stability of the femoral head, Matta and Merritt study based on clinical findings and suggested that the fracture crosses acetabular weight bearing dome when <45° medial, anterior and posterior roof arc angles 56.…”