Metric study of Egyptian sacrum for lumbo-sacral fixation procedures

Lumbo-sacral fixation for the management of lumbo-sacral instability includes insertion of screws to the sacrum, most commonly into the posterior aspect of the pedicles of the first sacralvertebra. This study was carried out to determine the normal anatomical parameters of the Egyptian sacrum, particularly of the first sacral vertebra and its pedicles, to find the safest approach for sacral screw placement in lumbo-sacral fixation procedures, and to describe racial characteristics, if any. In this study, 45 adult Egyptian dry sacra of unknown sex were used. Eleven sacral parameters were measured using the Vernier sliding caliper which is accurate to 0.1 millimeter. In this study, the sacrum showed a mean height of 11.43 ± 0.88 centimeters a mean width of 10.39 ± 0.91 centimeters with a mean sacral index of 90.82 ± 1.80 %. The first sacral pedicle had a mean anterior height of 1.83 ± 0.49 centimeters, a mean depth of 2.99 ± 0.53 centimeters and a mean posterior height of 2.38 ± 0.50 centimeters. A medialtrajectory path (representing an anteromedially-oriented first sacral pedicle screw) starting from the infero-lateral border of the S1 facet to the sacral promontory in the middle line was 5.23 ± 0.52 cm. The findings of the present study could provide accurate and specific parameters of the sacrum among Egyptians that could enhance the safety of insertion of sacral screws during lumbo-sacral fixation procedures upon Egyptian patients.