THE MECHANISM OF FEMORAL FRACTURE IN AN IMPACT ACCIDENT

Background: Following the crash of a Boeing 737-400 aircraft on the M1 motorway at Kegworth, near Nottingham, England, on January 8, 1989, i t became apparent that a large number of pelvic and lower limb injurie s had been sustained by the survivors. Had there been a fire, these in juries would have severely hindered the ability of the occupants to es cape. The mechanism of pelvic and lower limb injuries in impact accide nts previously has been related to flailing of the limbs and axial loa ding of the femur as in automobile accidents. Hypothesis: A bending lo ad is the primary mechanism of femoral fracture in an impact aircraft accident rather than an axial load. Methods: Two methods of study have been used to investigate the impact biomechanics of the pelvis and lo wer limb: a) clinical review of the injuries sustained in the M1 Kegwo rth accident; and b) impact testing. Results: A clinical review of the M1 aircrash survivors suggested that axial loading was not the primar y mechanism causing femoral fractures and suggested that a bending loa d might be applied to the femur. Impact testing confirmed that axial l oading of the femur did not appear to be significant. Conclusions: Our study suggests that in the presence of intact occupant protection sys tems, a femoral bending mechanism involving the front seat spar of pas senger seats is a primary cause of femoral fracture in an impact aircr aft accident.