Effects of retrograde femoral intramedullary nailing on the patellofemoral articulation.
OBJECTIVE
To determine the patellofemoral contact areas as well as mean and maximal pressures after retrograde intramedullary nailing in a cadaveric model.


METHODS
Pressure-sensitive film was used to analyze patellofemoral joint pressures after insertion of a retrograde femoral nail in a cadaveric specimen.


METHODS
A retrograde femoral nail was inserted into seven cadaveric knees. Pressure-sensitive film was placed into the patellofemoral joint and physiologic loads (700 newtons) were applied to the knee joint at 90 degrees and 120 degrees of flexion. Testing was performed with the nail three millimeters deep to the cartilage (In), flush with the cartilage (Flush), and one millimeter prominent (Out). The intact knee served as the Control.


RESULTS
The mean contact areas showed no statistical differences among the four groups. There was a significant increase in mean pressure at 120 degrees and maximum pressure at 90 degrees and 120 degrees for the Out group when compared with the Control, In, and Flush groups (p < 0.001).


CONCLUSIONS
There were no significant differences in mean contact pressure, contact area, or maximum pressure among the Control, three-millimeter insertion depth, or flush insertion groups. There was, however, a significant increase in mean and maximum pressures with the nail one millimeter prominent. These results indicate that placement of a retrograde femoral intramedullary nail is critical, but that proper placement should not significantly influence the biomechanics of the patellofemoral joint.
Morgan
E
E
Maryville Orthopedic Clinic, Tennessee, USA.
Ostrum
R F
RF
DiCicco
J
J
McElroy
J
J
Poka
A
A
D001696:Biomechanical Phenomena; D001858:Bone Nails; D002102:Cadaver; D005264:Femoral Fractures / Q000601:surgery; D005594:Fracture Fixation, Intramedullary; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D009068:Movement; D011312:Pressure