Side plate fixation vs. intramedullary nailing in an unstable medial femoral neck fracture model: A comparative biomechanical study.
BACKGROUND
The objective of this study was to investigate primary stability of the proximal femoral nailing antirotation for the indication of unstable medial femoral neck fractures. The device was compared to the dynamic hip screw blade, which is a "gold standard" in the treatment of proximal femoral fractures.


METHODS
Six pairs of human cadaver femurs were tested in a cyclic loading model with loads up to 200 N, 400 N, 600 N, 800 N, and 1000 N, respectively. Iliotibial tract was simulated by a chain that applied forces on the greater trochanter during loading. In vitro combined axial and bending loads were applied. Angular displacements during loading were recorded in all directions, and loads to failure were recorded.


RESULTS
For the cyclic loading test no statistically significant differences between the two groups could be detected. Specimens fixed with the dynamic hip screw blade showed higher displacements in the varus direction at 400 N and 600 N, in the external rotation at 200 N, 400 N and 600 N, and in the anterior direction at 400 N. Load to failure revealed no statistical difference between the two implants.


CONCLUSIONS
The proximal femoral nailing antirotation achieves primary stability comparable to the dynamic hip screw blade. The proximal femoral nailing antirotation combines the biomechanical favorable concept of intramedullary fixation with a minimally invasive surgical technique, which theoretically may be advantageous in clinical use. Further biomechanical studies are required to clarify to what extent the results of the present study can be transferred to the clinical situation.
Ulm University, Department of Orthopaedic Trauma, Ulm, Germany.
G
G
Röderer
S
S
Moll
F
F
Gebhard
L
L
Claes
G
G
Krischak
D000368:Aged; D000369:Aged, 80 and over; D015519:Bone Density; D001860:Bone Plates; D002102:Cadaver; D019245:Compressive Strength; D019544:Equipment Failure Analysis; D005260:Female; D005265:Femoral Neck Fractures / Q000150:complications / Q000503:physiopathology* / Q000601:surgery*; D005593:Fracture Fixation, Internal / Q000295:instrumentation*; D005594:Fracture Fixation, Intramedullary / Q000295:instrumentation*; D006801:Humans; D007593:Joint Instability / Q000209:etiology / Q000503:physiopathology* / Q000517:prevention & control*; D008297:Male; D011474:Prosthesis Design; D013718:Tensile Strength; D016896:Treatment Outcome