Bone mineral content and fixation strength of femoral neck fractures. A cadaver study.
We measured the bone mineral content (BMC) of 21 human femoral autopsy specimens using Radiographic Attenuation Technique (RAT). The specimens were then tested for stiffness in a material-testing machine. Osteosynthesis was performed after medial femoral neck osteotomy, using 1 of 3 different pinning methods: 2 hook pins (LIH), 2 cannulated screws (Uppsala), and 3 cannulated screws (CHP). The specimens were allocated to each method by grouping them in triplets with similar BMC. Cyclic loading at 500-1000 N and 1 Hz was performed during 50 minutes. The amount of axial compression during loading was measured. Finally, loading to failure was done and post-fixation stiffness and ultimate compression strength recorded. With one exception, all cases failed where the BMC was less than 0.4 g/cm2. No differences between the methods of osteosynthesis were found. The fixation strength was mostly dependent on the strength of the bone, i.e., the degree of osteoporosis.
Sjöstedt
A
A
Department of Orthopedics, East Hospital, Göteborg, Sweden.
Zetterberg
C
C
Hansson
T
T
Hult
E
E
Ekström
L
L
D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D015519:Bone Density; D001858:Bone Nails; D001863:Bone Screws; D004548:Elasticity; D005260:Female; D005265:Femoral Neck Fractures / Q000503:physiopathology* / Q000601:surgery*; D005593:Fracture Fixation, Internal / Q000379:methods*; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008422:Materials Testing; D008875:Middle Aged; D010027:Osteotomy