title: Spinal motion and intradiscal pressure measurements before and after lumbar spine instrumentation with titanium or PEEK rods.
abstract: Spinal instrumentation and fusion have been incriminated as contributing to adjacent segment degeneration (ASD). It has been suggested that ASD results from increased range of motion and intradiscal pressure (IDP) adjacent to instrumentation. Posterior dynamic stabilization with polyetheretherketone (PEEK) rods has been proposed as potentially advantageous compared to rigid instrumentation with titanium (Ti) rods in reducing the incidence of ASD. We evaluated segmental motions in the cadaveric spine instrumented with PEEK or Ti rods from L3 to S1, as well as the adjacent segment motions and IDP at L1-2 and L2-3. Human cadaveric spines were potted at T12-L1 and S1-2. Spinal instrumentation from L3-S1 was accomplished using pedicle screws with either PEEK or Ti rods. Specimens were subjected to displacement controlled testing: 15° flexion, 15° extension, 10° lateral bending, and 5° right axial rotation using the MTS machine (MTS, Minneapolis, MN, USA). Intradiscal pressure was measured by placing pressure transducers into the intervertebral disc at L1-2 and L2-3. Spinal motion of L2 relative to L3, and L3 relative to S1 was tracked using a three dimensional motion analysis system. Instrumentation with PEEK and Ti rods was associated with a decrease in L3-S1 motion compared to the intact state that was significant in flexion (p=0.002), and extension (p=0.0075). Instrumentation with PEEK and Ti rods was associated with an increase in IDP at L1-2 that was significant in flexion (p=0.0028). Instrumentation with either PEEK or Ti rods resulted in decreased motion at the instrumented levels while increasing IDP at the adjacent level.
authors: Department of Neurosurgery, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, Iowa City, IA 52242, USA. Electronic address: kingsley-abode-iyamah@uiowa.edu.
authors: Kingsley
authors: K
authors: Abode-Iyamah
authors: Department of Biomedical Engineering, University of Iowa Hospitals and Clinics, Iowa City, IA, USA.
authors: Sam Byeong
authors: SB
authors: Kim
authors: Department of Biomedical Engineering, University of Iowa Hospitals and Clinics, Iowa City, IA, USA.
authors: Nicole
authors: N
authors: Grosland
authors: Department of Neurosurgery, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, Iowa City, IA 52242, USA.
authors: Rajinder
authors: R
authors: Kumar
authors: Department of Neurosurgery, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, Iowa City, IA 52242, USA.
authors: Muhittin
authors: M
authors: Belirgen
authors: Department of Biomedical Engineering, University of Iowa Hospitals and Clinics, Iowa City, IA, USA.
authors: Tae Hong
authors: TH
authors: Lim
authors: Department of Preventive Medicine, University of Iowa Hospitals and Clinics, Iowa City, IA, USA.
authors: James
authors: J
authors: Torner
authors: Department of Neurosurgery, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, Iowa City, IA 52242, USA.
authors: Patrick W
authors: PW
authors: Hitchon
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001577:Benzophenones; D001696:Biomechanical Phenomena; D002102:Cadaver; D005260:Female; D006801:Humans; D007659:Ketones; D008159:Lumbar Vertebrae / Q000503:physiopathology* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D009038:Motion; D009984:Orthopedic Fixation Devices; D011092:Polyethylene Glycols; D011108:Polymers; D011312:Pressure; D016059:Range of Motion, Articular; D013123:Spinal Fusion / Q000295:instrumentation*; D014025:Titanium; D016896:Treatment Outcome
chemical_list: D001577:Benzophenones; D007659:Ketones; D011108:Polymers; C063834:polyetheretherketone; D011092:Polyethylene Glycols; D014025:Titanium
keywords: Adjacent segment disease; Biomechanics; Intradiscal pressure; Motion analysis; PEEK rods; Titanium rods