Where is the true location of the femoral piriform fossa?

OBJECTIVE

To analyze knowledge of the anatomic location of the piriform fossa using a questionnaire with anatomic figures.

MATERIALS AND METHODS

Participants taking AO Trauma Brasil courses were requested to complete a questionnaire containing a photograph of the superior surface and a photograph of the lateral surface of the femur and answer a question asking which of four numbered points corresponded to the piriform fossa.

RESULTS

Just 4.5% of respondents correctly chose point 2 (the piriform fossa) in both images, while 75.4% of respondents chose point 4 (the trochanteric fossa) as the correct anatomic structure. The subset of 4th-year residents' answers was significantly different from those of the other subsets, with 7.5% of correct answers.

CONCLUSIONS

The low rate of correct answers indicates a tendency for the respondents to be influenced by illustrations in text books or examples in scientific publications that indicate the site of the piriform fossa incorrectly. Interest in the specialty of traumatology is possibly the reason why the subset of 4th-year residents had a better- than-average rate of correct answers.

Increased incidence of femoral fractures in small femurs and women undergoing uncemented total hip arthroplasty - why?

The aim of this study was to investigate the relationship between the geometry of the proximal femur and the incidence of intra-operative fracture during uncemented total hip arthroplasty (THA). We studied the pre-operative CT scans of 100 patients undergoing THA with an uncemented femoral component. We measured the anteroposterior and mediolateral dimensions at the level of division of the femoral neck to calculate the aspect ratio of the femur. Wide variations in the shape of the femur were observed, from round, to very narrow elliptic. The femurs of women were narrower than those of men (p < 0.0001) and small femurs were also narrower than large ones. Patients with an intra-operative fracture of the calcar had smaller and narrower femurs than those without a fracture (p < 0.05) and the implanted Corail stems were smaller in those with a fracture (mean size 9 vs 12, p < 0.0001). The variability of the shape of the femoral neck at the level of division contributes to the understanding of the causation of intra-operative fractures in uncemented THA.