Biomechanical comparison of the fixation after curved periacetabular osteotomy using titanium and bioabsorbable screws.

Abstract

We performed curved periacetabular osteotomy, a modification of the Bernese periacetabular osteotomy, to treat hip dysplasia. The purpose of our study was to compare the biomechanical stability of acetabular fragments fixed in place with 3 titanium screws, or with 2 or 3 bioabsorbable screws composed of particulate resorbable uncalcined hydroxyapatite (HA) and poly-L-lactic acid (PLLA) termed HA/PLLA screws. Curved periacetabular osteotomy was performed on 24 composite model hemipelves. Three groups of 8 specimens were affixed with 1) 3 titanium screws, 2) 2 HA/PLLA screws, or 3) 3 HA/PLLA screws. After fixation, the hemipelves were biomechanically attested with simulated push-off phase of the gait cycle using a servohydraulic material testing system. The average failure loads were not significantly different among the3 groups tested. However, the group repaired with 3 HA/PLLA screws showed significantly greater stiffness than the other groups. All 3 fixation methods provided sufficient stability to allow for early partial weight-bearing after surgery. The use of 3 HA/PLLA screws provided significantly greater stiffness for acetabular fragment fixation.