The effect of plate luting on reduction accuracy and biomechanics of acetabular osteotomies stabilized with 2.7-mm reconstruction plates

Objective - To compare the accuracy of reduction and biomechanical characteristics of acetabular osteotomies repaired with luted and nonluted reconstruction plates. Study Design - In vitro study. Animals - Pelves removed from 12 adult greyhounds. Methods - Acetabular osteotomies were created and repaired with a 6-hole, 2.7-mm reconstruction plates in 24 cadaver hemipelves. Ten hemipelves each were assigned to group I and group II. An impression cast of each acetabulum in group I was made before luting (preluting cast). Group I plates were then elevated, luted, and replaced. A second cast of each acetabulum in group I was then made (postluting cast). Step, gap, and total areas of articular osteotomy incongruence were determined from the casts. Group I (luted plate repairs) and group II (nonluted plate repairs) hemipelves were loaded ventral-to-dorsal using a materials-testing machine. Stiffness, yield load, and maximal load sustained were determined. Results - Mean gap and total area of articular osteotomy incongruence for group I preluted plate repairs (7.1 mm ² and 8.6 mm², respectively) were significantly greater than for group I postluted plate repairs (4.1 mm² and 5.1 mm ², respectively). Mean stiffness and maximal load for group I (681 N/mm and 2,555 N, respectively) were significantly greater than for group II (360 N/mm and 1,730 N, respectively). Mean step area and mean load at yield values were not significantly different between groups. Conclusions - Luted plate repairs of osteotomized acetabulae result in improved reduction and are stiffer and stronger than nonluted plate repairs. Clinical Significance - Plate luting may improve the accuracy of reduction of acetabular fractures where anatomic reduction is required. Plate luting may also increase the stiffness and strength of fracture repairs and arthrodeses.