Blunt impact @entity130 to the patellofemoral joint during car accidents, sporting activities, and falls can produce a range of injuries to the knee joint, including gross @entity174 , @entity3145 , and/or microinjuries to bone and soft tissue. Currently, the only well-established @entity3331 criterion applies to knee impacts suffered during car accidents. This criterion is based solely on the peak impact load delivered to seated cadavers having a single knee flexion angle. More recent studies, however, suggest that the injury potential, its location, and the characteristics of the damage are also a function of knee flexion angle and the stiffness of the impacting structure. For example, at low flexion angles, @entity174 are common with a rigid impact interface, while at high flexion angles splitting of the femoral condyles is more evident. Low stiffness impact surfaces have been previously shown to distribute impact loads over the anterior surface of the patella to help mitigate gross and microscopic injuries in the 90 deg flexed knee. The objective of the current study was to determine if a deformable impact interface would just as effectively mitigate gross and microscopic injuries to the knee at various flexion angles. Paired experiments were conducted on contralateral knees of 18 @entity1 cadavers at three flexion angles (60, 90, 120 deg). One knee was subjected to a @entity174 level impact experiment with a rigid impactor, and the opposite knee was impacted with a deformable interface (3.3 MPa crush strength honeycomb material) to the same load. This (deformable) impact interface was effective at mitigating gross bone @entity174 at approximately 5 kN at all flexion angles, but the frequency of split @entity174 of the femoral condyles may not have been significantly reduced at 120 deg flexion. On the other hand, this deformable interface was not effective in mitigating microscopic injuries observed for all knee flexion angles. These new data, in concert with the existing literature, suggest the chosen impact interface was not optimal for @entity3331 protection in that @entity174 and other @entity130 were still produced. For example, in 18 cadavers a total of 20 gross @entity174 and 20 subfracture injuries were produced with a rigid interface and 5 gross @entity174 and 21 subfracture injuries with the deformable interface selected for the current study. Additional studies will be needed to optimize the knee impact interface for protection against gross and microscopic injuries to the knee.

Impact responses of the flexed XXXX knee using a deformable impact interface.

@entity1 :: ('9606', 'Species') :: ['human'] @entity174 :: ('MESH:D050723', 'Disease') :: ['fractures', 'fracture', 'fractures of the distal patella', 'bone fracture'] @entity3145 :: ('MESH:D017695', 'Disease') :: ['soft tissue injury'] @entity3331 :: ('MESH:D007718', 'Disease') :: ['knee injury'] @entity130 :: ('MESH:D014947', 'Disease') :: ['trauma', 'minor injuries']
@entity1 :: (9606,Species) :: ['human']
