Optimizing Cervicothoracic Junction Biomechanics after C7 Pedicle Subtraction Osteotomy: A Cadaveric Study of Stability and Rod Strain

Authors

Jakub Godzik, Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA.
Jennifer N. Lehrman, Spinal Biomechanics Laboratory, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA.Follow
S Harrison Farber, Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA.
Bernardo de Andrada Pereira, Spinal Biomechanics Laboratory, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA.Follow
Anna G. Sawa, Spinal Biomechanics Laboratory, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA.
Christopher P. Ames, Department of Neurological Surgery, University of California, San Francisco, California, USA.
Heiko Koller, Department of Neurosurgery, Technical University of Munich, Munich, Germany.
Kevin Lee, DePuySynthes Spine Inc., Raynham, Massachusetts, USA.
Jay D. Turner, Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA.
Brian P. Kelly, Spinal Biomechanics Laboratory, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona, USA. Electronic address: Neuropub@barrowneuro.org.Follow

Document Type

Article

Abstract

OBJECTIVE: To compare biomechanical stability and rod strain among uniform rod (UR), tapered rod (TR), and UR+accessory rod (AR) constructs in a human cadaveric C7 pedicle subtraction osteotomy (PSO) model of cervical deformity correction. METHODS: Fourteen human cadaveric C2-T4 specimens were divided into 2 statistically equivalent groups. Specimens were instrumented from C2 to T3, and a 25° PSO was performed at C7. Group 1 was instrumented with 3.5-mm to 5.5-mm titanium TRs, and group 2 received 4.0-mm titanium URs. The UR group was also tested with lateral 4.0-mm titanium ARs (UR+AR) at C5-T2. All conditions were tested with 2.0 Nm pure moment and 70 N compressive load. Intervertebral range of motion (ROM) and posterior rod strain (pRS) were measured at C2-C3, T2-T3, and the PSO level. Statistical comparisons used 1-way analysis of variance. RESULTS: ROM was significantly reduced in the TR versus UR construct for right axial rotation (P = 0.04) at the PSO level; ROM with TR was significantly greater than with UR and UR+AR in compression (P ≤ 0.02). At the PSO level, pRS was significantly greater in TR than in UR+AR in flexion, extension, and right axial rotation (P ≤ 0.02). At T2/3, pRS was higher in UR than TR in left axial rotation (P = 0.003). CONCLUSIONS: C7 PSO is highly destabilizing. Maximal rod strain was concentrated across the PSO and the cranial fixation site. TR provided higher stability than did UR in 1 direction of movement; however, UR+AR provided the greatest reduction of pRS.

Keywords

Accessory rod, Biomechanics, Cervical deformity, Cervicothoracic junction, Pedicle subtraction osteotomy, Rod strain

Publication Date

1-6-2022

Publication Title

World neurosurgery

E-ISSN

1878-8769

PubMed ID

34999263

Digital Object Identifier (DOI)

10.1016/j.wneu.2022.01.002

Recommended Citation

Godzik, Jakub; Lehrman, Jennifer N.; Farber, S Harrison; de Andrada Pereira, Bernardo; Sawa, Anna G.; Ames, Christopher P.; Koller, Heiko; Lee, Kevin; Turner, Jay D.; and Kelly, Brian P., "Optimizing Cervicothoracic Junction Biomechanics after C7 Pedicle Subtraction Osteotomy: A Cadaveric Study of Stability and Rod Strain" (2022). Translational Neuroscience. 1218.
https://scholar.barrowneuro.org/neurobiology/1218