title: Torsional stability of the femoral component of hip arthroplasty. Response to an anteriorly applied load.
abstract: Torsional instability of femoral components has not received much attention, and is difficult to detect in conventional radiographs. To test this we designed a system to apply a load in an anteroposterior direction to the head of a femoral component, implanted into a cadaveric femur. Rotation within the bone was measured, using a purpose built transducer, with and without preservation of the neck, with and without cement, and with longitudinal ridges but no cement. The results show that torsional instability may be a problem in uncemented replacement. Preservation of the femoral neck and the use of a ridged prosthesis increases resistance to rotation. Rotational movements occurring in vivo during such activities as climbing stairs and rising from the seated position may contribute to mechanical loosening.
authors.affiliation: Bone and Joint Research Unit, London Hospital Medical College, England.
authors.forename: D
authors.initials: D
authors.lastname: Nunn
authors.forename: M A
authors.initials: MA
authors.lastname: Freeman
authors.forename: K E
authors.initials: KE
authors.lastname: Tanner
authors.forename: W
authors.initials: W
authors.lastname: Bonfield
mesh_terms: D001696:Biomechanical Phenomena; D005265:Femoral Neck Fractures / Q000503:physiopathology; D006622:Hip Prosthesis; D006801:Humans; D011474:Prosthesis Design; D013314:Stress, Mechanical