Biomechanics of the lower thoracic spine after decompression and fusion: a cadaveric analysis

Mechanical response of human thoracic spine ligaments under quasi-static loading: An experimental study

PURPOSE

This study aimed to investigate the geometrical and mechanical properties of human thoracic spine ligaments subjected to uniaxial quasi-static tensile test.

METHODS

Four human thoracic spines, obtained through a body donation program, were utilized for the study. The anterior longitudinal ligament (ALL), posterior longitudinal ligament (PLL), capsular ligament (CL), ligamenta flava (LF), and the interspinous ligament and supraspinous ligament complex (ISL + SSL), were investigated. The samples underwent specimen preparation, including dissection, cleaning, and reinforcement, before being immersed in epoxy resin. Uniaxial tensile tests were performed using a custom-designed mechanical testing machine equipped with an environmental chamber (T = 36.6 °C; humidity 95%). Then, the obtained tensile curves were averaged preserving the characteristic regions of typical ligaments response.

RESULTS

Geometrical and mechanical properties, such as initial length and width, failure load, and failure elongation, were measured. Analysis of variance (ANOVA) revealed significant differences among the ligaments for all investigated parameters. Pairwise comparisons using Tukey's post-hoc test indicated differences in initial length and width. ALL and PLL exhibited higher failure forces compared to CL and LF. ALL and ISL + SSL demonstrated biggest failure elongation. Comparisons with other studies showed variations in initial length, failure force, and failure elongation across different ligaments. The subsystem (Th1 - Th6 and Th7 - Th12) analysis revealed increases in initial length, width, failure force, and elongation for certain ligaments.

CONCLUSIONS

Variations of both the geometric and mechanical properties of the ligaments were noticed, highlighting their unique characteristics and response to tensile force. Presented results extend very limited experimental data base of thoracic spine ligaments existing in the literature. The obtained geometrical and mechanical properties can help in the development of more precise human body models (HBMs).

Mid- to Long-Term Outcomes After Resection of Thoracic Dumbbell Tumors Managed by Laminectomy and Unilateral Total Facetectomy Without Instrumented Fusion

STUDY DESIGN

Retrospective multicenter study.

OBJECTIVE

To evaluate mid- to long-term surgical outcomes of thoracic dumbbell tumors managed by laminectomy and unilateral total facetectomy without instrumented fusion.

METHODS

A total of 15 patients with thoracic dumbbell tumors who underwent primary resection by laminectomy and unilateral total facetectomy without spinal instrumented fusion between 2000 and 2015 were reviewed. Patient characteristics, surgical outcomes (including spinal alignment and stability), disc degeneration, pain, disability, and health-related quality of life were evaluated. Additionally, to analyze the impact of the affected levels on these outcomes, we divided the patients into 2 groups: a middle thoracic group and a thoracolumbar group.

RESULTS

The mean duration of follow-up was 100.5 months (range, 36-190 months). The affected level was T3-T4 or below in all patients. Although the local kyphosis angle (8.1° to 12.7°), thoracic kyphosis angle (25.6° to 33.9°), and coronal Cobb angle (6.6° to 9.5°) significantly increased from preoperative to the final visit (P ≤ .02), no patient demonstrated spinal instability. From magnetic resonance imaging, no patient had a worse grade of disc degeneration in the affected level than those in the adjacent levels. The percentage of patients who presented with an Oswestry disability index ≤ 22% was 80%. Moreover, the surgical region did not adversely affect the outcomes. No patient required additional surgery due to spinal instability or deformity.

CONCLUSIONS

Unilateral total facetectomy without fusion to resect thoracic dumbbell tumors caused neither spinal deformity nor instability requiring additional surgery at the mid- to long-term follow-up.

The Gantry Crane Technique: A Novel Technique for Treating Severe Thoracic Spinal Stenosis and Myelopathy Caused by Ossification of the Ligamentum Flavum and Preliminary Clinical Results

STUDY DESIGN

Retrospective single-arm study.

OBJECTIVE

To propose a novel technique named the gantry crane technique for treating severe thoracic spinal stenosis and myelopathy caused by thoracic ossification of the ligamentum flavum (TOLF) and investigate its clinical results.

METHODS

From June 2017 to January 2019, 18 patients presenting with severe spinal stenosis and myelopathy caused by TOLF were included in our study. All patients were treated with gantry crane technique, pre-operative JOA score, as well as 3 days-, 3 months-, 6 months-, 12 months-, 24 months after operation, and Hirabayashi recovery rate were reported. Pre- and post-operative image were utilized for the assessment of post-operative effect. Peri-operative complications were recorded to assess the safety of the gantry crane technique.

RESULTS

The JOA score increased from 10.56 ± 3.76 preoperatively to 12.94 ± 3.33, 13.56 ± 3.48, 13.94 ± 3.32, 14.17 ± 3.70 and 14.06 ± 3.54 in 3 days, 3 months, 6 months, 12 months and 24 months after surgery, respectively. The post-operative JOA scores were improved with statistical significance at the level of P < 0.05. The recovery rate was (39.09 ± 33.85) %, (51.35 ± 42.60) %, (55.79 ± 36.10) %, (64.98 ± 29.24) % and (60.98 ± 35.96) % for 3 days, 3 months, 6 months, 12 months and 24 months after surgery, respectively. There were 2 cases of SSI (surgical site infection), 1 case of NI (neurovascular injury) and 1 case of cerebrospinal fluid (CSF) leakage.

CONCLUSIONS

This study highlights a safe and effective technique, the gantry crane technique, for treating severe thoracic spinal stenosis and myelopathy caused by TOLF.

"Cave-in" decompression under unilateral biportal endoscopy in a patient with upper thoracic ossification of posterior longitudinal ligament: Case report

Background

Thoracic ossification of the posterior longitudinal ligament (TOPLL) requires surgery for spinal cord decompression. Traditional open surgery is extremely invasive and has various complications. Unilateral biportal endoscopy (UBE) is a newly developed technique for spine surgery, especially in the lumbar region, but rare in the thoracic spine. In this study, we first used a different percutaneous UBE "cave-in" decompression technique for the treatment of beak-type TOPLL.

Methods

A 31-year-old female with distinct zonesthesia and numbness below the T3 dermatome caused by beak-type TOPLL (T2-T3) underwent a two-step UBE decompression procedure. In the first step, the ipsilateral lamina, left facet joint, partial transverse process, and pedicles of T2 and T3 were removed. In the second step, a cave was created by removing the posterior third of the vertebral body (T2-T3). The eggshell-like TOPLL was excised by forceps, and the dural sac was decompressed. All procedures are performed under endoscopic guidance. A drainage tube was inserted, and the incisions were closed after compliance with the decompression scope via a C-arm. The patient's preoperative and postoperative radiological and clinical results were evaluated.

Results

Postoperative CT and MR films conformed complete decompression of the spinal cord. The patient's lower extremity muscle strength was greatly improved, and no complications occurred. The mJOA score improved from 5 to 7, with a recovery rate of 33.3%.

Conclusion

UBE spinal decompression for TOPLL showed favorable clinical and radiological results and offers the advantages of minimal soft tissue dissection, shorter hospital stays, and a faster return to daily life activities.

Research of a Safe and Simplified Intertransverse Process Approach for the Lower Thoracic Interbody Surgery

Objective

To assess a safe surgical approach for intertransverse process lower thoracic intervertebral body fusion (ITIF) based on measurements from enhanced three‐dimensional CT reconstruction, cadaver simulated operation, and patient operation.

Methods

Enhanced three‐dimensional CT image reconstruction was performed for 20 healthy volunteers on thoracic segments T8–T12. The length of the transverse process (LTP), distance between the upper and lower transverse processes (DULTP), remote distance of the transverse process (RDTP), height of the extraforaminal intervertebral space (HEIS), and oblique diameter of the intervertebral space (ODIS) were measured and recorded. The blood vessels of the intertransverse lower thoracic region were observed, and their internal diameters were measured. The rib‐intervertebral space relationship for T10/11 and T11/12 was measured in 104 patients of the thoracic skeleton. Then, based on the data from the CT measurements, simulated surgery was performed on six human cadavers at the T11/12 level. An ankylosing spondylitis (AS) patient with a fracture of the T10/11 level was eventually operated on with the ITIF technique.

Results

No significant difference was found between the lengths of the left and right thoracic transverse processes. The relationship of the values of the LTP and RDTP for the measured vertebrae were found to be as follows:T8 > T9 > T10 > T11 > T12. For HEIS and DULTP, T8–9 < T9–10 < T10–11 < T11–12. The results for the ODIS were as follows: T8–T9 < T9–T10 < T10–T11 < T11–T12. The blood vessel inner diameter of T11–12 was less than that of T10–11, while there was no significant difference between the diameters for T8–9 and T11–12. Almost half of the volunteer's T10/11 intervertebral spaces were covered posteriorly by the 11th rib (45.19% on left and 41.35% on right), while for most patients, the T11/12 intervertebral space was not covered by the 12th rib (98.08%). According to the cadaver experiments, intervertebral bone grafting and ipsilateral pedicle screw fixation were performed to simulate the operation. One patient with a combined AS and T10/11 fracture was then operated on with the ITIF technique and followed up for 3 years with satisfactory results.

Conclusion

As verified by 3D CT reconstruction measurements, cadaver simulation surgery and patient operation with follow‐up, the intertransverse process approach for some T10/T11 and almost all T11/T12 segments is a safe surgical pathway for operations such as ITIF, fracture bone grafting, clearance of focal lesions.

How Does the Rib Cage Affect the Biomechanical Properties of the Thoracic Spine? A Systematic Literature Review

The vast majority of previous experimental studies on the thoracic spine were performed without the entire rib cage, while significant contributive aspects regarding stability and motion behavior were shown in several other studies. The aim of this literature review was to pool and increase evidence on the effect of the rib cage on human thoracic spinal biomechanical characteristics by collating and interrelating previous experimental findings in order to support interpretations of in vitro and in silico studies disregarding the rib cage to create comparability and reproducibility for all studies including the rib cage and provide combined comparative data for future biomechanical studies on the thoracic spine. After a systematic literature search corresponding to PRISMA guidelines, eleven studies were included and quantitatively evaluated in this review. The combined data exhibited that the rib cage increases the thoracic spinal stability in all motion planes, primarily in axial rotation and predominantly in the upper thorax half, reducing thoracic spinal range of motion, neutral zone, and intradiscal pressure, while increasing thoracic spinal neutral and elastic zone stiffness, compression resistance, and, in a neutral position, the intradiscal pressure. In particular, the costosternal connection was found to be the primary stabilizer and an essential determinant for the kinematics of the overall thoracic spine, while the costotransverse and costovertebral joints predominantly reinforce the stability of the single thoracic spinal segments but do not alter thoracic spinal kinematics. Neutral zone and neutral zone stiffness were more affected by rib cage removal than the range of motion and elastic zone stiffness, thus also representing the essential parameters for destabilization of the thoracic spine. As a result, the rib cage and thoracic spine form a biomechanical entity that should not be separated. Therefore, usage of entire human non-degenerated thoracic spine and rib cage specimens together with pure moment application and sagittal curvature determination is recommended for future in vitro testing in order to ensure comparability, reproducibility, and quasi-physiological validity.

Optimal Anchor at the Uppermost Instrumented Vertebra in Long Fusion From the Pelvis to the Lower Thoracic Spine in Elderly Patients With Degenerative Spinal Deformity: Hook Versus Pedicle Screw

STUDY DESIGN

This was a retrospective cohort study.

OBJECTIVE

The objective of this study was to compare pedicle screws (PSs) and transverse process hooks (TPHs) as anchors at the uppermost instrumented vertebra (UIV) in the lower thoracic spine in elderly patients with adult spinal deformity.

SUMMARY OF BACKGROUND DATA

Less-rigid fixation using hooks at the UIV are thought to best prevent proximal junctional kyphosis (PJK) in long spinal fusion surgery. Although adult spinal deformity is commonly treated via spinal fusion from the pelvis to the lower thoracic spine, few studies have focused on UIV anchors in the lower thoracic spine.

MATERIALS AND METHODS

We retrospectively reviewed 53 patients aged 65 years and above who underwent spinal fusion from the pelvis to T9 or T10, with a minimum follow-up of 1 year. Radiographic outcomes including the incidence of PJK and implant failure were compared between 28 patients with TPHs and 25 patients PSs at the UIV.

RESULTS

The TPH and PS groups had similar radiographic values for pelvic incidence-lumbar lordosis (preoperative: 42.8 vs. 49.0 degrees, postoperative: 9.9 vs. 7.3 degrees) and the sagittal vertical axis (preoperative: 109.3 vs. 106.8 mm; postoperative: 21.9 vs. 11.2 mm). However, the incidence of PJK was significantly higher in the TPH group (35.7%) than that in the PS group (8.0%) at the 1-year follow-up (P=0.012). PJK in the TPH group was associated with UIV or UIV±1 fracture accompanied by posterior dislodgement of the TPH.

CONCLUSION

Rigid fixation using PSs at the UIV in the lower thoracic spine produced better radiographic outcomes than did TPHs in elderly patients undergoing spinopelvic fusion.

LEVEL OF EVIDENCE

Level III.

In vitro comparison of personalized 3D printed versus standard expandable titanium vertebral body replacement implants in the mid-thoracic spine using entire rib cage specimens

BACKGROUND

Expandable titanium implants have proven their suitability as vertebral body replacement device in several clinical and biomechanical studies. Potential stabilizing features of personalized 3D printed titanium devices, however, have never been explored. This in vitro study aimed to prove their equivalence regarding primary stability and three-dimensional motion behavior in the mid-thoracic spine including the entire rib cage.

METHODS

Six fresh frozen human thoracic spine specimens with intact rib cages were loaded with pure moments of 5 Nm while performing optical motion tracking of all vertebrae. Following testing in intact condition (1), the specimens were tested after inserting personalized 3D printed titanium vertebral body replacement implants (2) and the two standard expandable titanium implants Obelisc™ (3) and Synex™ (4), each at T6 level combined with posterior pedicle screw-rod fixation from T4 to T8.

FINDINGS

No significant differences (P < .05) in primary and secondary T1-T12 ranges of motion were found between the three implant types. Compared to the intact condition, slight decreases of the range of motion were found, which were significant for Synex™ in primary flexion/extension (-17%), specifically at T3-T4 level (-46%), primary lateral bending (-18%), and secondary lateral bending during primary axial rotation (-53%). Range of motion solely increased at T8-T9 level, while being significant only for Obelisc™ (+35%).

INTERPRETATION

Personalized 3D printed vertebral body replacement implants provide a promising alternative to standard expandable devices regarding primary stability and three-dimensional motion behavior in the mid-thoracic spine due to the stabilizing effect of the rib cage.

Thoracic Spinal Stability and Motion Behavior Are Affected by the Length of Posterior Instrumentation After Vertebral Body Replacement, but Not by the Surgical Approach Type: An in vitro Study With Entire Rib Cage Specimens

Spinal tumors and unstable vertebral body fractures usually require surgical treatment including vertebral body replacement. Regarding primary stability, however, the best possible treatment depends on the spinal region. The purpose of this in vitro study was to evaluate the effects of instrumentation length and approach size on thoracic spinal stability including the entire rib cage. Six fresh frozen human thoracic spine specimens with intact rib cages (C7-L1) were loaded with pure moments of 5 Nm in flexion/extension, lateral bending, and axial rotation, while monitoring the relative motions of all spinal segments using optical motion tracking. The specimens were tested (1) in the intact condition, followed by testing after vertebral body replacement at T6 level using a unilateral approach combined with (2) long instrumentation (T4-T8) and (3) short instrumentation (T5-T7) as well as a bilateral approach combined with (4) long and (5) short instrumentation. Significant increases of the range of motion (p < 0.05) were found in the entire thoracic spine (T1-T12) using the bilateral approach and short instrumentation in primary flexion/extension and in secondary axial rotation during primary lateral bending compared to both conditions with long instrumentation, as well as in secondary lateral bending during primary axial rotation compared to unilateral approach and long instrumentation. Compared to the intact condition, the range of motion was significantly decreased using unilateral approach and long instrumentation in flexion extension and secondary lateral bending during primary axial rotation, as well as using bilateral approach and long instrumentation in lateral bending. On the segmental level, the range of motion was significantly increased at T4-T5 level in lateral bending using unilateral approach and short instrumentation and significantly decreased using bilateral approach and long instrumentation compared to their respective previous conditions. Regardless of the approach type, which did not affect thoracic spinal stability in the present study, short instrumentation overall shows sufficient primary stability in the mid-thoracic spine with intact rib cage, while creating considerably more instability compared to long instrumentation, potentially being of importance regarding long-term implant failure. Moreover, short instrumentation could affect adjacent segment disease due to increased motion at the upper segmental level.

Intervertebral Displacement of the Thoracic Spine with and without Loading: Radiographic and in Vitro Measurements

BACKGROUND

We are developing an intradural approach to spinal cord stimulation, where the thin electrode array is affixed stably to the underside of the thoracic spinal dura mater without leakage of cerebrospinal fluid. As part of the design and testing process, we sought to evaluate the potential risk of inadvertent contact of the array with the pial surface of the spinal cord during variations in spinal loading.

METHODS

As part of the risk assessment process, a 2-part study was undertaken. First, a retrospective review of the imaging studies of 25 patients was done in the supine, 45- and 90-degree positions to measure the positional shift between the T9 and T10 vertebral bodies as a function of spinal angulation. Second, similar measurements were made on a cadaveric model, with and without a prototype intradural stimulator implanted at the T9-T10 position and with and without 13.8 kg (30 lb) of axial spinal loading at the 90-degree orientation.

RESULTS

In all cases, the measured relative displacement of the dura mater towards the spinal cord in both the imaging and the cadaveric arms of the study was less than 1 mm.

CONCLUSIONS

The implantation method for the thin intradural array of the prototype device will ensure that the anatomic separation between it and the pial surface of the spinal cord will be the same as that of the dura mater. Therefore the risk of inadvertent contact will be no greater than that due to the mass effects of standard epidural stimulator implants.

Stabilizing effect of the rib cage on adjacent segment motion following thoracolumbar posterior fixation of the human thoracic cadaveric spine: A biomechanical study

BACKGROUND

Although the rib cage provides substantial stability to the thoracic spine, few biomechanical studies have incorporated it into their testing model, and no studies have determined the influence of the rib cage on adjacent segment motion of long fusion constructs. The present biomechanical study aimed to determine the mechanical contribution of the intact rib cage during the testing of instrumented specimens.

METHODS

A cyclic loading (CL) protocol with instrumentation (T4-L2 pedicle screw-rod fixation) was conducted on five thoracic spines (C7-L2) with intact rib cages. Range of motion (±5 Nm pure moment) in flexion-extension, lateral bending, and axial rotation was captured for intact ribs, partial ribs, and no ribs conditions. Comparisons at the supra-adjacent (T2-T3), adjacent (T3-T4), first instrumented (T4-T5), and second instrumented (T5-T6) levels were made between conditions (P ≤ 0.05).

FINDINGS

A trend of increased motion at the adjacent level was seen for partial ribs and no ribs in all 3 bending modes. This trend was also observed at the supra-adjacent level for both conditions. No significant changes in motion compared to the intact ribs condition were seen at the first and second instrumented levels (P > 0.05).

INTERPRETATION

The segment adjacent to long fusion constructs, which may appear more grossly unstable when tested in the disarticulated spine, is reinforced by the rib cage. In order to avoid overestimating adjacent level motion, when testing the effectiveness of surgical techniques of the thoracic spine, inclusion of the rib cage may be warranted to better reflect clinical circumstances.

The rib cage stiffens the thoracic spine in a cadaveric model with body weight load under dynamic moments

The thoracic spine presents a challenge for biomechanical testing. With more segments than the lumbar and cervical regions and the integration with the rib cage, experimental approaches to evaluate the mechanical behavior of cadaveric thoracic spines have varied widely. Some researchers are now including the rib cage intact during testing, and some are incorporating follower load techniques in the thoracic spine. Both of these approaches aim to more closely model physiological conditions. To date, no studies have examined the impact of the rib cage on thoracic spine motion and stiffness in conjunction with follower loads. The purpose of this research was to quantify the mechanical effect of the rib cage on cadaveric thoracic spine motion and stiffness with a follower load under dynamic moments. It was hypothesized that the rib cage would increase stiffness and decrease motion of the thoracic spine with a follower load. Eight fresh-frozen human cadaveric thoracic spines with rib cages (T1-T12) were loaded with a 400 N compressive follower load. Dynamic moments of ± 5 N m were applied in lateral bending, flexion/extension, and axial rotation, and the motion and stiffness of the specimens with the rib cage intact have been previously reported. This study evaluated the motion and stiffness of the specimens after rib cage removal, and compared the data to the rib cage intact condition. Range-of-motion and stiffness were calculated for the upper, middle, and lower segments of the thoracic spine. Range-of-motion significantly increased with the removal of the rib cage in lateral bending, flexion/extension, and axial rotation by 63.5%, 63.0%, and 58.8%, respectively (p < 0.05). Neutral and elastic zones increased in flexion/extension and axial rotation, and neutral zone stiffness decreased in axial rotation with rib cage removal. Overall, the removal of the rib cage increases the range-of-motion and decreases the stiffness of cadaveric thoracic spines under compressive follower loads in vitro. This study suggests that the rib cage should be included when testing a cadaveric thoracic spine with a follower load to optimize clinical relevance.

Challenging the Conventional Standard for Thoracic Spine Range of Motion: A Systematic Review

BACKGROUND

Segmental motion is a fundamental characteristic of the thoracic spine; however, studies of segmental ranges of motion have not been summarized or analyzed. The purpose of the present study was to present a summary of the literature on intact cadaveric thoracic spine segmental range of motion in each anatomical plane.

METHODS

A systematic MEDLINE search was performed with use of the terms "thoracic spine," "motion," and "cadaver." Reports that included data on the range of motion of intact thoracic human cadaveric spines were included. Independent variables included experimental details (e.g., specimen age), type of loading (e.g., pure moments), and applied moment. Dependent variables included the ranges of motion in flexion-extension, lateral bending, and axial rotation.

RESULTS

Thirty-three unique articles were identified and included. Twenty-three applied pure moments to thoracic spine specimens, with applied moments ranging from 1.5 to 8 Nm. Estimated segmental range of motion pooled means ranged from 1.9° to 3.8° in flexion-extension, from 2.1° to 4.4° in lateral bending, and from 2.4° to 5.2° in axial rotation. The sums of the range of motion pooled means (T1 to T12) were 28° in flexion-extension, 36° in lateral bending, and 45° in axial rotation.

CONCLUSIONS

The pooled ranges of motion were similar to reported in vivo motions but were considerably smaller in magnitude than the frequently referenced values reported prior to the widespread use of biomechanical testing standards. Improved reporting of biomechanical testing methods, as well as specimen health, may be beneficial for improving on these estimations of segmental cadaveric thoracic spine range of motion.

3D correction over 2years with anterior vertebral body growth modulation: A finite element analysis of screw positioning, cable tensioning and postoperative functional activities

BACKGROUND

Anterior vertebral body growth modulation is a fusionless instrumentation to correct scoliosis using growth modulation. The objective was to biomechanically assess effects of cable tensioning, screw positioning and post-operative position on tridimensional correction.

METHODS

The design of experiments included two variables: cable tensioning (150/200N) and screw positioning (lateral/anterior/triangulated), computationally tested on 10 scoliotic cases using a personalized finite element model to simulate spinal instrumentation, and 2years growth modulation with the device. Dependent variables were: computed Cobb angles, kyphosis, lordosis, axial rotation and stresses exerted on growth plates. Supine functional post-operative position was simulated in addition to the reference standing position to evaluate corresponding growth plate's stresses.

FINDINGS

Simulated cable tensioning and screw positioning had a significant impact on immediate and after 2years Cobb angle (between 5°-11°, p<0.01). Anterior screw positioning significantly increased kyphosis after 2years (6°-8°, p=0.02). Triangulated screw positioning did not significantly impact axial rotation but significantly reduced kyphosis (8°-10°, p=0.001). Growth plates' stresses were increased by 23% on the curve's convex side with cable tensioning, while screw positioning rather affected anterior/posterior distributions. Supine position significantly affected stress distributions on the apical vertebra compared to standing position (respectively 72% of compressive stresses on convex side vs 55%).

INTERPRETATION

This comparative numerical study showed the biomechanical possibility to adjust the fusionless instrumentation parameters to improve correction in frontal and sagittal planes, but not in the transverse plane. The convex side stresses increase in the supine position may suggest that growth modulation could be accentuated during nighttime.

Thoracic range of motion, stability, and correlation to imaging-determined degeneration

OBJECT The degenerative process of the spinal column results in instability followed by a progressive loss of segmental motion. Segmental degeneration is associated with intervertebral disc and facet changes, which can be quantified. Correlating this degeneration with clinical segmental motion has not been investigated in the thoracic spine. The authors sought to determine if imaging-determined degeneration would correlate with native range of motion (ROM) or the change in ROM after decompressive procedures, potentially guiding clinical decision making in the setting of spine trauma or following decompressive procedures in the thoracic spine. METHODS Multidirectional flexibility tests with image analysis were performed on thoracic cadaveric spines with intact ib cage. Specimens consisted of 19 fresh frozen human cadaveric spines, spanning C-7 to L-1. ROM was obtained for each specimen in axial rotation (AR), flexion-extension (FE), and lateral bending (LB) in the intact state and following laminectomy, unilateral facetectomy, and unilateral costotransversectomy performed at either T4-5 (in 9 specimens) or T8-9 (in 10 specimens). Image grading of segmental degeneration was performed utilizing 3D CT reconstructions. Imaging scores were obtained for disc space degeneration, which quantified osteophytes, narrowing, and endplate sclerosis, all contributing to the Lane disc summary score. Facet degeneration was quantified using the Weishaupt facet summary score, which included the scoring of facet osteophytes, narrowing, hypertrophy, subchondral erosions, and cysts. RESULTS The native ROM of specimens from T-1 to T-12 (n = 19) negatively correlated with age in AR (Pearson's r coefficient = -0.42, p = 0.070) and FE (r = -0.42, p = 0.076). When regional ROM (across 4 adjacent segments) was considered, the presence of disc osteophytes negatively correlated with FE (r = -0.69, p = 0.012), LB (r = -0.82, p = 0.001), and disc narrowing trended toward significance in AR (r = -0.49, p = 0.107). Facet characteristics, scored using multiple variables, showed minimal correlation to native ROM (r range from -0.45 to +0.19); however, facet degeneration scores at the surgical level revealed strong negative correlations with regional thoracic stability following decompressive procedures in AR and LB (Weishaupt facet summary score: r = -0.52 and r = -0.71; p = 0.084 and p = 0.010, respectively). Disc degeneration was not correlated (Lane disc summary score: r = -0.06, p = 0.861). CONCLUSIONS Advanced age was the most important determinant of decreasing native thoracic ROM, whereas imaging characteristics (T1-12) did not correlate with the native ROM of thoracic specimens with intact rib cages. Advanced facet degeneration at the surgical level did correlate to specimen stability following decompressive procedures, and is likely indicative of the terminal stages of segmental degeneration.