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.
Department of Orthopaedic Surgery, University of Pittsburgh Medical Center, Pennsylvania 15213, USA.
M J
MJ
Prayson
D K
DK
Datta
M P
MP
Marshall
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