clinical outcomes of the trinica(r) anterior lumbar plate: fixed screws vs. variable screws

Conditions: Degenerative Disc Disease; Spinal Stenosis; Spondylolisthesis

Summary: trinica anterior lumbar plate (alp) system is a commercially available, supplemental fusion device for use in the lumbar or sacral spine (l1-s1) to treat instability. the system provides the surgeon with the ability to supplement an interbody device with anterior plate fixation. the device's bone-plate interface is enhanced through use of fixed-angled screws,variable-angle screws or a combination of both to accommodate various combinations of screw configurations, resulting in enhanced fixation tailored to individual patient needs. clinical outcomes data, including a comparison of different screw configurations, is needed to support the use and of the trinica alp system.

in the cervical spine, literature shows that a static plate utilizing fixed screws loses its ability to load share and to limit motion following subsidence of the interbody spacer. in contrast, a dynamic plate system utilizing variable-angle screws maintains load-sharing and stiffness following subsidences. increasing the load on the bone graft in the interbody space increases the rate of graft fusion. although literature exists supporting the in vivo use of anterior cervical plate systems and the advantages of screw angulation, there is no data evaluating and supporting the use of anterior plate systems in the lumbar spine. the different biomechanical loads between cervical and lumbar spine suggest cervical data may not generalize to the lumbar spine. additionally, it will be useful to characterize the effect of different screw configurations on subsidence and stress shielding and fusion success. the proposed study will not only assess clinical outcomes following trinica alp implantation, but will also provide valuable comparison data regarding two different screw configurations. the study is a prospective, randomized, between groups design. the subject pool will be comprised of individuals who are appropriate for spinal fusion surgery, and who meet the inclusion criteria. subjects will be randomly assigned to one of three screw configurations. all subjects will receive structural allograft (puros a anterior allograft) as interbody support. other procedures identified by the surgeon to be in the best interest of the patient may be completed but are not required by the protocol.

Eligibility criteria:
inclusion criteria: * spinal stenosis * spondylolisthesis degenerative disc disease (defined as back pain of discogenic origin with degeneration of the disc confirmed by history and radiographic studies) * fracture (including dislocation or subluxation) * spine tumor * scoliosis * lordotic deformities of the spine exclusion criteria: * an active systemic or local infection * previous fusion attempt at index level * a local inflammation with or without fever or leukocytosis * pregnancy * obesity (bmi \>40 kg/m2) * drug or alcohol abuse * uncooperativeness or neurological or mental illness rendering the individual unwilling or unable to follow instructions * inability to restrict high activity level * a suspected or documented metal allergy or intolerance * a poor prognosis for good wound healing (e.g., decubitus ulcer, end-stage diabetes, severe protein deficiency and/or malnutrition) * any medical or surgical condition that would preclude the potential benefit of spinal implant surgery, prevent secure component fixation, or seriously increase the risk of tolerating any surgical procedure, * any other "contraindications" as enumerated in the device's "instructions for use".

Keywords: degenerative disc disease spinal stenosis spondylolisthesis alif fusion success anterior lumbar plate fixed versus variable screw configurations anterior lumbar interbody fusion to treat spinal instability