In Vitro Investigation of Column Fixation Constructs for Periacetabular Osteotomy: Which Provide the Greatest Stiffness and Strength?

Background: Periacetabular osteotomy (PAO) is an effective surgical procedure for managing acetabular dysplasia. The purpose of this study was to analyze the biomechanical properties of novel PAO constructs that incorporate orthopaedic trauma techniques. We hypothesize that these fixation methods will create a stiffer construct that tolerates higher loads to failure. Methods: Twenty bio-composite hemi-pelvises underwent PAO with the following fixation configurations: Group A: 4 iliac crest (IC) screws; Group B: 3 IC screws; Group C: 2 IC screws, 1 retrograde anterior column (AC) screw, and 1 lateral compression type-2 (LC2) screw directed from the anterior inferior iliac spine to the posterior inferior iliac spine; Group D: 1 AC screw, 1 LC2 screw, 1 posterior column screw; Group E: 2 LC2 screws, 1 AC screw. Constructs were loaded to failure on a material testing hydraulic press, and ultimate strength, stiffness, and osteotomy displacement were measured. Results: The highest load to failure was seen in group D (2511 N), which was significantly more than groups A (1528 N, P = .0114) and B (1348 N, P < .0001). The stiffest construct was group E (602 N/mm) compared to groups A (315 N/mm, P = .0439) and B (243 N/mm, P = .0008). Failure occurred most often with a fracture in the posterior column. Conclusions: This study supports column fixation methods used in orthopaedic trauma for PAO as biomechanically advantageous to traditional fixation techniques. These constructs may be beneficial to patients with weight-bearing concerns or early rehabilitation needs.