Impacted PLIF: Posterior Lumbar Interbody Fusion with Machined, Pre-Sized Allograft

Kevin Foley, MD
Thomas Lee, MD (White Plains, NY)
Ramesh Sahjpaul, MD (London, Ontario)

Purpose: To assess the utility of impacted, machined allograft for posterior lumbar interbody fusion used in conjunction with laminar autograft and pedicle screw fixation.

Materials and Methods: Thirty–three patients (mean age 50.5 years) with intractable mechanical low back and radicular pain from spondylolisthesis, post–operative instability, recurrent herniated disc, or lumbar degenerative disc disease were treated. Two pre–sized, machined cortical allografts (Regeneration Technologies, Incorporated) and laminectomy autograft were used for PLIF. Pedicle screw fixation was performed with the titanium TSRH system. Forty levels of impacted PLIF were performed in 33 patients. Mean follow–up was 10.5 months (range 7–14 months). Radiographs were obtained at 1, 3, 6, and 12 months, then as needed.

Results: No neurological or infectious complications were noted, including no retraction–related radiculopathy. Mean hospital stay was 3.2 days. All 33 patients reported significantly reduced lower back pain. 30 of 32 patients with radicular pain noted significant improvement. By 6 months, 30 of 33 patients had returned to previous occupation and level of activity. Radiographic fusion was noted in 31 patients (94%), with two patients having partial graft incorporation at the time of most recent follow–up.

Conclusions: Impacted PLIF seems to be effective for relief of mechanical low back and radicular pain associated with several lumbar spine disorders. Fusion rates compare favorably to other procedures. Relatively short hospital stays may be secondary to the avoidance of extensive paraspinous muscle dissection and graft harvesting. Retraction–related radiculopathy is minimized by the narrow width of the implants. Fusion assessment is aided by the lack of metallic interbody devices. These results are preliminary and need to be validated by longer–term follow–up.