Quantification of the upper and second sacral segment safe zones in normal and dysmorphic sacra.
ABSTRACT To quantify the obliquity and dimensions of the upper and second sacral segment iliosacral screw safe zones and to determine the differences between normal and dysmorphic sacral morphology.
University Level I trauma center.
Fifty patients with pelvic computed tomography scans.
All sacra were characterized as normal or dysmorphic based on plain pelvic radiographs and previously described criteria. Multiple computed tomography scan reconstructions were viewed and manipulated simultaneously with 6 degrees of freedom to allow for custom visualization in any plane.
In each patient, a unique reconstruction plane was created perpendicular to the safe zone axis. The narrowest safe zone cross-sectional area was measured. Next, on simulated pelvic outlet and inlet views, safe zone obliquity and width were measured. Finally, the space available for a transverse screw was assessed. Measurements were performed for both upper and second sacral segment. Values for normal and dysmorphic safe zones were compared.
Sacral dysmorphism was identified in 22 patients. In these sacra, the upper sacral segment safe zone cross-section was 36% smaller than in normal sacra (P < 0.001). No transverse screws could be placed, but accommodating for the caudal to cranial obliquity (30° versus 21° in normals, P < 0.001) and posterior to anterior obliquity (15% versus 4% in normals, P < 0.001) of the safe zone, an iliosacral screw at least 75 mm in length could be placed safely in 91% of patients. A transverse screw could be placed in 75% of normal sacra. In the second segment safe zone, the cross-sectional area was more than twice as large in dysmorphic sacra compared to normals (220 mm versus 109 mm, P < 0.001). The obliquity was not different on either the inlet or outlet views between groups. A transverse screw could be placed at this level in 95% of those with dysmorphic sacra and in only 50% of normal sacra.
Sacral dysmorphism occurred in 44% of patients in this consecutive series. Many anatomic differences were consistently found between the two morphologies with clinical relevance to iliosacral screw placement. Specifically, the dysmorphic upper sacral segment safe zone is significantly smaller and more obliquely oriented but is still large enough to accommodate an iliosacral screw in nearly all patients. The second sacral segment safe zone is approximately transversely oriented in both sacral types but is more than twice as large in dysmorphic sacra. This segment may be a primary fixation opportunity in patients with sacral dysmorphism.
- [Show abstract] [Hide abstract]
ABSTRACT: Obesity can complicate surgical procedures by both adding to difficulty intraoperatively and increasing post-operative complications. Intraoperative imaging can be difficult on morbidly obese patients. We have noted specifically that in morbidly obese patients where the lateral sacrum cannot be visualized on the pre-operative scout CT image, the lateral sacrum will not be able to be seen on intraoperative fluoroscopy. This is an important component of preoperative planning in morbidly obese patients with pelvic ring injuries.Journal of orthopaedic trauma 05/2012; 27(5). DOI:10.1097/BOT.0b013e31826046b0 · 1.54 Impact Factor
- 06/2012; 72(6):1502-9. DOI:10.1097/TA.0b013e318246efe5
- [Show abstract] [Hide abstract]
ABSTRACT: Due to the aging population, we are confronted with a growing number of osteoporotic and insufficiency fractures of the pelvic ring. They are the result of a low-energy trauma. With conventional X-rays, it is not always possible to identify the lesions. In all cases, additional CT or MRI examinations are necessary. The morphology of the lesions is very variable and represents a spectrum of instability. Conventional classification is not applicable for all fracture types. Therapy includes a wide range between conservative and operative concepts. The choice of treatment is determined by the degree and the localization of the instability. Osteosynthesis techniques differ from the techniques we use in adults. The trans-sacral positioning bar, iliolumbar fixation and angle stable plate osteosynthesis are used increasingly often.Zeitschrift fur Orthopadie und Unfallchirurgie 06/2012; 150(3):e107-18; quiz e119-20. DOI:10.1055/s-0032-1314948 · 0.62 Impact Factor