Hybrid dynamic stabilization with posterior spinal fusion in the lumbar spine

Anterior-posterior (A) and lateral (B) plain films showing an example of the posterior hybrid construct with laminectomies and interbody fusions at L4-5 and L5-S1, as well as posterior lateral fusions at these levels. The dynamic portion of the rod is placed at the cephalad (L3-4) level.

A 37-year-old woman after discectomies at L4-5 and L5-S1, with degenerative disc disease at L3-4, L4-5, and L5-S1 (A). She also had a positive discogram at L3-4 (B), L4-5 (C), and L5-S1 (D) with a normal disc at L2-3. She underwent an L4-S1 fusion with dynamic instrumentation at L3-4.

Left, Discogram showing pathologic morphology at both the L5-S1 and the L4-5 levels. A non-painful level with normal architecture was mandatory at the L3-4 cephalad segment. Right, Computed tomography discogram with pathologic morphology at both L4-5 and L5-S1. Both of these levels are fully concordant; the L3-4 level presents normal morphology and a negative discogram. This patient underwent an L4-5 fusion with dynamic instrumentation at L4-5.

Plain film radiograph showing method for measurement of disc height ratio (DHR): DHR = (a + b)/H.

Mean values for radiographic measurement of disc height ratio at each visit.

Mean values for radiographic measurement of intervertebral angle at each visit.

Mean values for radiographic measurement of angular mobility at each visit.

Radiographic evidence of screw loosening. The “halo” around the L4 and L5 screws in the vertebral body and pedicle should be noted. This patient also presented with a pseudarthrosis of the L5-S1 interspace at 4 years postoperatively and underwent revision to an L4-S1 fusion and repair of the pseudarthrosis.

Isobar TTL (Scient'x USA). The dampener mechanism has 0.75 mm of compression and 2° of angulation built in.