Biomechanical evaluation of retrograde intramedullary stabilization for femoral fractures: the effect of fracture level.
BACKGROUND
Retrograde stabilization of mid-diaphysis adolescent femur fractures has shown excellent biomechanical stability. However, it is unclear whether adequate stability is maintained for distal femur fractures using the retrograde approach compared with the clinically recommended antegrade approach. The purpose of this study was to evaluate the biomechanical stability of retrograde and antegrade nailing for mid-diaphyseal and distal diaphysis femoral fractures.


METHODS
Twenty adolescent-sized synthetic femurs were randomly assigned to fracture location and surgical approach groups. Comminuted fractures were simulated at the mid-diaphysial level and 4 cm proximal to the distal physis. The retrograde approach used 2 c-shaped 3.5-mm titanium nails. The antegrade used c and s 3.5-mm nail configurations. Both techniques achieved maximum nail divergence at the level of the fracture. Biomechanical testing was conducted to determine differences in torsional range of motion (degrees)and failure load (N) at 5 mm. These data were analyzed with a 2-way analysis of variance (p < 0.05).


RESULTS
In torsion, there were no differences related to surgical approach or fracture level. For axial compression to 5 mm, the antegrade approach required significantly greater force to achieve 5 mm of compression compared with the retrograde approach. The mid-diaphyseal fracture required significantly greater force to achieve 5 mm of compression compared with the distal diaphysis group.


CONCLUSIONS
For maximum stabilization of a distal femur fracture, c- and s-shaped nails placed in the antegrade position is suggested.


CONCLUSIONS
Surgical decision making regarding the use of either the antegrade or retrograde approach will be influenced by both the stability provided (antegrade) and the ease of insertion (retrograde).
Goodwin
Ryan
R
Department of Orthopedic Surgery, The Cleveland Clinic Foundation, Cleveland, OH, USA.
Mahar
Andrew T
AT
Oka
Richard
R
Steinman
Suzanne
S
Newton
Peter O
PO
D001696:Biomechanical Phenomena; D002648:Child; D004867:Equipment Design; D005264:Femoral Fractures / Q000503:physiopathology* / Q000601:surgery*; D005593:Fracture Fixation, Internal; D005594:Fracture Fixation, Intramedullary; D006801:Humans; D008954:Models, Biological