[A morphologic evaluation of the sacroiliac joint and plate fixation on a pelvic model using a S1 pedicular screw, transiliosacral screws, and a compression rod for sacroiliac joint injuries].
OBJECTIVE
Morphological measurements were performed, of the articular surfaces and adjacent bone structures of the sacroiliac joint on dry bone specimens to determine the projection of the sacroiliac joint on the outer table of the posterior ilium. In addition, the effect of plate fixation using transiliosacral screws and a pedicular screw on S1 attached via a compression rod was evaluated on pelvic models to be applied in sacroiliac joint injuries.


METHODS
Quantitative caliper measurements of dry bone specimens including 20 os coxae and 10 sacrum were made on the articular surfaces of the sacrum and the posterior ilium, thickness of the posterior iliac bone at different levels, and the distance from the outer walls of S1 and S2 foramina to the sacral facies articularis. After the construction of a plate matching the projection of the lateral sacral mass on the outer table of the posterior ilium, four transiliosacral screws were applied lateral to the sacral foramina on pelvic models. A pedicular screw sent to S1 was attached to the plate with a threaded compression rod.


RESULTS
The mean values for the articular surface of (i) the posterior ilium were 53.3 mm (base length), 38.5 mm (height), and 56.2 mm (the distance from the anterior margin of the articular surface to the spina iliaca posterior superior); and (ii) the sacrum, 57.2 mm (base length), and 34.6 mm (height). The mean thickness of the posterior ilium was 19.2 mm, and the mean distance from the lateral walls of the sacral foramina at S1 and S2 levels to the articular surface was 21.7 mm. For the deduced projection, the perpendicular line from the middle of the base was found to be the safe zone for screw applications.


CONCLUSIONS
Through a plate applied matching the projection area, multiple screws may be sent lateral to S1 and S2 foraminal levels without damage to the sacral neural and surrounding vital structures. A stable fixation can be achieved by combining the plate/screw system with a S1 pedicular screw.
Esenkaya
Irfan
I
Inönü Universitesi Tip Fakültesi Ortopedi ve Travmatoloji Anabilim Dali, Malatya, Turkey. iesenkaya@hotmail.com
D001860:Bone Plates; D001863:Bone Screws; D002102:Cadaver; D005593:Fracture Fixation, Internal / Q000379:methods*; D006801:Humans; D004204:Joint Dislocations / Q000601:surgery*; D012446:Sacroiliac Joint / Q000033:anatomy & histology / Q000293:injuries* / Q000601:surgery*