Mechanical comparison of endosteal substitution and lateral plate fixation in supracondylar fractures of the femur.
OBJECTIVE
To assess for improved rigidity with the addition of a medial endosteal plate to laterally plated supracondylar femoral fractures.


METHODS
A randomized paired study in a supracondylar femoral fracture model comparing two fixation methods tested cyclically in axial and torsional loading.


METHODS
One-centimeter supracondylar gap osteotomies were created in twenty synthetic femurs approximately six centimeters proximal to the knee joint. Ten were stabilized with a lateral eight-hole buttress plate alone, and ten were secured by a similar lateral buttress plate plus a medial endosteal eight-hole dynamic compression plate. Group 1 (n = 5; lateral plate alone) and Group 2 (n = 5; lateral and endosteal plates) were axially loaded up to 700 newtons through a materials test system for three cycles. A displacement transducer detected movement at the medial fracture gap. Group 3 (n = 5; lateral plate alone) and Group 4 (n = 5; lateral and endosteal plates) were tested in torsion. A rod-and-pulley system created an external rotation torque up to twenty Newton-meters for three cycles. A rotary potentiometer measured angular displacement.


RESULTS
Lateral buttress plating with endosteal substitution showed statistically significant decreased motion at the fracture site in torsional (p < 0.004) and axial loading (p < 0.0001) versus lateral buttress plating alone using Student's t test.


CONCLUSIONS
The addition of a 4.5-millimeter endosteal plate to a lateral buttress plate provides significantly increased stability, as compared with lateral plating alone in a femoral supracondylar fracture model during simulated axial and torsional loading. Neither fixation construct, however, restored the torsional stability of the distal femur to its preinjury (intact) level.
Prayson
M J
MJ
Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, Pennsylvania 15213, USA.
Datta
D K
DK
Marshall
M P
MP
D001696:Biomechanical Phenomena; D001860:Bone Plates; D005264:Femoral Fractures / Q000601:surgery*; D005593:Fracture Fixation, Internal / Q000295:instrumentation* / Q000379:methods; D005594:Fracture Fixation, Intramedullary / Q000295:instrumentation* / Q000379:methods; D006801:Humans; D008953:Models, Anatomic; D011897:Random Allocation; D012680:Sensitivity and Specificity; D016474:Weight-Bearing