Sacral Plating Techniques (Chopin)

Jeff S. Silber

Description

The Chopin plate, also known as the Colorado II sacral plate, combines an S1 screw and a laterally placed sacral alar screw. It was introduced by Chopin in France and has been used in clinical practice since the early 1990s. The two-hole plate, or three-hole plate if pelvic fixation is also required, is placed on the dorsal aspect of the sacrum in a longitudinal direction (Fig. 44.1 ). The superior hole is for placement of an S1 pedicle screw angled medially (10 to 15 degrees) toward the sacral promontory, and the inferior hole is for placement of a sacral alar screw angled laterally (30 degrees). With the three-hole plate an additional hole located laterally can be utilized for fixation into the pelvis (Fig. 44.2 ). Located midway between the superior and inferior holes is a post that allows connection of the plate to the longitudinal component extending down from the lumbar spine.

Fig. 44.1 Side view of the two-hole plate.

Fig. 44.2 Axial view of the three-hole plate.

Expectations

Spinal pathology involving the lumbar-sacral junction may be due to trauma, infection, tumor, or congenital or degenerative disease. Commonly, fusion procedures need to include this junction to obtain stability and improve the overall biomechanics of the spine. Increased fusion rates have been reported with the use of instrumentation, and although posterior sacral pedicle screws are widely used, cases of fixation failure have been reported with their use. Screw failure is most commonly due to inadequate purchase, incorrect direction or depth of screw placement, and osteoporotic bone, especially in the setting of long fusion procedures that place high bending loads across this junction. Overall, based on biomechanical testing, S1 screws placed anteromedially into the sacral promontory with bicortical purchase tend to have the highest pullout and bending strength. Furthermore, the Chopin (Colorado II plate) may add additionally needed fixation points across the lumbosacral junction in various clinical scenarios.

Indications

Biomechanical studies have demonstrated improved strength using this divergent two-screw construct compared with a single pedicle screw construct alone. This technique is especially useful in cases of highgrade (III–V) spondylolisthesis, long fusions to the sacrum, revision procedures, pseudarthrosis at the L5-S1 level, significant osteoporosis, sacral trauma, and scoliosis (neuromuscular) with pelvic obliquity requiring sacral and pelvic fixation.

Contraindications

This technique should not be used if fusion to the pelvis and sacrum is not indicated or needed.

Special Considerations

The posterior-superior iliac spine may need to be removed or at least flattened with a rongeur or burr to make the plate seat flush against the pelvis.

Tips, Pearls, and Lessons Learned

Unicortical versus bicortical screw placement is based on surgeon preference, as the increased pullout strength provided by the technique is due to the divergent placement of the two screws. If further pelvic fixation is needed, a three-hole plate utilizing a pelvic screw placed through the posterior-superior iliac spin may be utilized.

Upon completion, intraoperative fluoroscopy or plain radiographs are obtained to confirm adequate screw placement and appropriate spinal alignment.