In patients where the proximal femur shows gross deformity due
to degenerative changes or fracture, the contralateral femur is
often used to perform preoperative templating for hip arthroplasty.
However, femurs may not be symmetrical: the aim of this study was
to determine the degree of variation between hips in healthy individuals and
to determine whether it is affected by demographic parameters. CT-scan based modelling was used to examine the pelvis and bilateral
femurs of 345 patients (211 males, 134 women; mean age 62 years
(standard deviation (Aims
Materials and Methods
Lumbar spondylolysis is a stress fracture of the pars interarticularis. We have evaluated the site of origin of the fracture clinically and biomechanically. Ten adolescents with incomplete stress fractures of the pars (four bilateral) were included in our study. There were seven boys and three girls aged between 11 and 17 years. The site of the fracture was confirmed by axial and sagittal reconstructed CT. The maximum principal tensile stresses and their locations in the L5 pars during lumbar movement were calculated using a three-dimensional finite-element model of the L3-S1 segment. In all ten patients the fracture line was seen only at the caudal-ventral aspect of the pars and did not spread completely to the craniodorsal aspect. According to the finite-element analysis, the higher stresses were found at the caudal-ventral aspect in all loading modes. In extension, the stress was twofold higher in the ventral than in the dorsal aspect. Our radiological and biomechanical results were in agreement with our clinical observations.
