Cervical Intradiscal Pressure Responses to End-Range Supine Postures: A Cadaveric Investigation

doi:10.21203/rs.3.rs-4837798/v1

Download PDF

Research Article

Cervical Intradiscal Pressure Responses to End-Range Supine Postures: A Cadaveric Investigation

https://doi.org/10.21203/rs.3.rs-4837798/v1

This work is licensed under a CC BY 4.0 License

You are reading this latest preprint version

Background: Neck postures can affect cervical intradiscal pressure (CIDP) and contribute to intervertebral disc (IVD) pathologies. Despite neck flexion and protraction posture prevalence and potential impact on cervical IVD health, no studies have investigated CIDP during end-range protraction and retraction. This study investigated (1) CIDP differences between cervical traction, six sagittal plane cervical end-ranges, and neutral posture; (2) CIDP and segmental cervical range of motion (ROM) correlation; and (3) CIDP measurement reliability.

Methods: Seven cadaveric specimens, mean age 80.6±7.2 years, had cervical segmental ROM assessed by lateral radiographs and CIDP responses measured by fiberoptic pressure sensors in C4-5, C5-6, and C6-7 IVDs for supine end-range chin to neck, chin to sternum, protraction-flexion, occiput to neck, occiput to thorax, retraction-extension, and neutral traction.

Results: Friedman tests revealed greater CIDP in (1) chin to sternum as compared to traction at C4-5, C5-6 and C6-7 (p<.02); (2) chin to sternum as compared to retraction-extension at C5-6 and C6-7 (p=.027); and (3) chin to sternum as compared to protraction-flexion at C5-6 (p=.042). End-range postures demonstrated moderate effect sizes on CIDP at C4-5 (ES=.31), C5-6 (ES=.46), and C6-7 (ES=.36) using Kendall’s W. Strong correlations between cervical segmental ROM and CIDP were identified at C4-5 chin to neck, r_S=.79, p=.04; C5-6 occiput to thorax, r_S=.79, p=.04; and C6-7 protraction-flexion, r_S=.82, p=.02. Reliability was good to excellent for CIDP and segmental ROM measurements (ICC>.92, 95%CI .86-.98).

Conclusions: Consistent chin to sternum increases and traction decreases in CIDP occurred at all cervical IVD levels. The CIDP tended to increase during flexion end-ranges at all IVD levels, while extension, protraction, and retraction tended to decrease at C5-6, C6-7 and increase at C4-5. Large positive or negative CIDP variations with even larger standard deviations were observed within and between cervical IVD segments during various postures.

Intervertebral Disc

Cervical Vertebrae

Pressure

Range of Motion.

Cervical spine conditions are prevalent in the United States and affect nearly two thirds of individuals during the lifespan.^1–4 Pain originates from many sources in the cervical spine, including muscles, ligaments, zygapophyseal joints, and the intervertebral discs (IVDs). Discogenic pain accounts for approximately 20% of all cervical spine pathology. ^1–3,5,6 The lower cervical IVDs are prone to early, multi-level degeneration and result in internal and external IVD disruptions, foraminal and central stenosis, and nerve root compression syndromes.^7–11 Progressive cervical spine degeneration results in disability for 70% of the population.^1–4

Cervical intradiscal pressure (CIDP) indicates overall IVD health, assists end plate fluid nutrition diffusion, and is affected in degenerated IVDs.^{4,7,10,12–15} Increased CIDP correlates with IVD degeneration,^{4,7,10,12–14} while decreased CIDP can be indicative of annular weaknesses, disc rupture, and potential leakage of nuclear material.^11,16 Cervical postures, especially in the sagittal plane, affect CIDP and may accelerate IVD degeneration.^{7,9,10,12–14,17−20} These postures are increasingly commonplace due to human technology interface usage and are identified as “text neck” and “video display terminal syndrome”.^21–23 Previous studies have examined CIDP in cadaveric specimen with varying postures and identified increased CIDP in flexion and end range extension, while CIDP were reduced in axial rotation and lateral bending^{6,7,9,10,17,20}; however, these postures were limited in range of motion (ROM) excursion and performed in vitro with mechanical testing simulators. Investigations of other common cervical spine sagittal plane postures including chin to neck flexion, chin to sternum flexion, occiput to neck extension, occiput to upper back extension, protraction, or retraction and their effect on CIDP in the lower cervical IVD were limited and focused only on ROM and biomechanics.^2,22,24–26

Most CIDP studies primarily examined the changes occurring in the IVDs following surgical interventions such as IVD replacements and fusions, with emphasis on differences between pre- and post-operative CIDP.^{7,9,10,12,14,17–19} Most authors only assessed CIDP at two levels to accommodate surgical fixation of two or more IVD segments.^{7,10,12,14,18,19} The IVD levels monitored for pressure changes varied among studies, but were most prevalent at C4-5 and C6-7.^7,9,14,18,19 Several studies examined CIDP responses at three or more IVD levels.^{6,15,16,20,27}

Of particular note is the paucity of CIDP assessment in vivo or in situ. Only one study examined CIDP and volume capacity in healthy versus degenerated IVDs in 19 patients under anesthesia prior to surgical intervention.^27,28 Another weakness in CIDP current knowledge is the lack of pressure response at the C5-6 IVD level, which was typically the location of surgical fixation in many of the identified studies.^{7,9,14,17–19} This gap in CIDP responses at C5-6 represents significant challenges for conservative care as it is one of the most common levels of IVD pathology in the lower cervical spine.⁵

Cervical pain and ROM limitations occurring after sleep are commonly reported at least once per week by most adults.² As such, the decision was made to assess CIDP responses in the supine position, since people spend significant time in recumbency during sleep, leisure activities, and many clinical evaluative and treatment procedures. Another omission in studies examining CIDP was the exclusion of cervical protraction and retraction postures. The CIDP has been demonstrated to increase in sagittal plane ROM^{7,10,12,14,17–20}; however, we do not know CIDP responses in the lower cervical IVDs during protraction and retraction postures, which are commonly held during technology use with handheld electronic devices.^2,21–23

Conservative treatment approaches use sagittal plane postures for manual therapy interventions, as well as exercise prescription to address cervical IVD pathologies. Selected authors addressed effects of cervical traction in cadaveric specimens, revealing decreased CIDP corresponding with distraction forces.^6,29 A singular in situ study investigated prone manual cervical distraction on nine cadaveric specimens and reported lower CIDP at the C4 to T1 IVD levels during the technique.¹⁵ Of particular interest is cervical retraction, which is a necessary movement to maximally flex the upper cervical spine segments and is a core component of many treatment strategies to address postural dysfunction and discogenic pain.^{2,23,25,26,30}

Despite widespread use of cervical retraction to treat cervical IVD pathology, objective information regarding effects of this posture on CIDP are unknown and efficacy is determined by empirical evidence alone.^25,26 Understanding the effects of sagittal plane end-range postures on CIDP could help guide methods of identification, prevention, and management of cervical IVD conditions.

The purpose of this study was to investigate in human cadaveric specimens the CIDP differences between six sagittal plane end-range cervical postures and traction in neutral, the correlation between CIDP and cervical segmental range of motion (ROM), and the measurement reliability.

The investigation aimed to establish in human un-embalmed cadaveric specimens (1) CIDP differences between neutral posture with cervical traction and six sagittal plane end-range cervical postures including chin to neck, chin to sternum, protraction with flexion, occiput to neck, occiput to thorax, and retraction with extension (Fig. 1); (2) CIDP differences between each of the lower cervical IVD levels; (3) the correlation between CIDP and cervical segmental ROM, and (4) the CIDP measurements intra-rater reliability during end-range cervical postures in the sagittal plane in supine.

Research Design

Experimental test-retest reliability study and pre-test, post-test repeated measures design.

Specimens and Sample Size

A convenience sampling of ten un-embalmed human cadavers were acquired through the département d’anatomie de l’Université du Québec à Trois-Rivières and the study protocol was approved by the Ethics Subcommittee for use of cadaveric material (SCELERA-21-06). Inclusion criteria consisted of adult, willed body donor, un-embalmed cadavers. Exclusion criteria were any known cervical spine surgery history, cervical spine trauma, cervical ROM limitations greater than 50%³¹, cervical spine cancer or significant systemic conditions impairing cervical joint mobility, and radiographic evidence of advanced degenerative cervical spine disease. Two cadavers were excluded secondary to radiographic findings including severe degenerative changes and complete fusion of the C4-5 vertebral bodies. A third specimen sustained a C6-7 IVD rupture during end-range posture radiographs and was unable to maintain pressurization for further testing. Four female and three male cadaveric specimens with a mean age of 80.6±7.2 years, mean height of 1.6±0.1 m, mean weight of 57.9±11.8 kg, and mean body mass index of 21.6±2.9 were included in the study.

Preparatory Procedures

Demographic information including sex, age, height, weight, body mass index, and cause of death were recorded for all specimens during intake of willed body donors by the département d’anatomie de l’Université du Québec à Trois-Rivières. Investigator-1, a physical therapist with 23 years of clinical experience and advanced national certification in musculoskeletal physical therapy, performed and reviewed lateral radiographs to rule out cervical spine exclusion criteria.^{6,9,10,12–16,18−20,29,32} After radiographic verification, an anterior midline dissection was performed to expose the anterior surfaces of the cervical spine to allow visualization of the C4 to C7 IVDs.^1,8,13,14

Identification and placement of a metal marker on the C3 vertebral body was performed and immediately verified by lateral radiograph (Fig. 2A).

The cadaver was positioned and secured by straps with the T2 spinous process at the edge of the table and the head supported on a portable instrument tray. Investigator-1 positioned cadavers in each sagittal plane end-range posture including neutral without traction, chin to neck (Fig. 2B), chin to sternum, protraction with flexion, occiput to neck, occiput to thorax, and retraction with extension while investigator-2 obtained lateral radiographs using standardized imaging parameters.^23,25,33 Radiographic images were saved and later measured segmental ROM for each IVD segment in all seven postures.

Following ROM assessment, 1 and ½ inch 18-gauge needles were inserted into the C4-5, C5-6, and C6-7 IVDs.^12–15 Each segment IVD space was identified counting caudally from the previously marked C3 vertebral body and visually verified for bulging of the IVD during cervical flexion, extension, and lateral flexion movements. Needles were inserted into IVDs and immediately removed and flushed to eliminate annulus material clogging. Careful reinsertion of the needle into initial entrance holes was necessary to prevent IVD pressurization loss. Several water drops were placed in each needle and observed for displacement during cervical ROM, indicating successful IVD positioning with resultant pressure changes during movement. Needle placement within IVDs was verified by lateral radiographs (Fig. 2C) with repositioning and subsequent re-verification as necessary.^{1,7–10,13−15,18} Sutures were placed within the anterior vertebral ligament to maintain needle position. Cotton patches and tissue glue were placed and cured for five minutes to re-enforce needle placement.

Instrumentation

The CIDP was measured at the C4-5, C5-6, and C6-7 IVD levels simultaneously with three FISO FPI-HR-2 fiberoptic pressure sensors with range ±300 mm Hg and accuracy ±1 mm Hg (FISO Technologies Inc., Québec, QC, Canada).^{10,12,14,17,18,20} Pressure chamber systems were constructed from a 4-way stopcock with swivel male Luer lock, an injection adapter with MLL 1 and 7/16 inches, a 17-inch Appx 0.48 mL smallbore ext set with MicroClave clear clamp Luer lock for direct attachment to the IVD needle, and a 10 mL syringe filled with water (Fig. 3). All pressure chamber systems components were pre-loaded with water to eliminate air. Fiberoptic sensors labeled with corresponding IVD levels were introduced by 18-gauge needles into the injection adapter chamber. Needles were retracted once sensors were located in the chambers. Pressure system chambers were visually inspected to ensure no air present prior to connecting 17-inch tubing to IVD needles. Preloading IVDs was accomplished introducing up to 0.1 mL water prior to testing and as needed to maintain pressure responses during repeated trials.^16,27

The OptiTrack 3D motion analysis system (NaturalPoint, Inc., Corvallis, OR, USA) ensured consistency performing repeated sagittal plane end-range postures during Phases 1 and 2. Comparison of OptiTrack to other three-dimensional motion analysis systems demonstrated excellent proficiency with linear measurement accuracy and reliability.^34–36 Data collection occurred in a designated laboratory area with fixed global axes and camera placements for three-dimensional visualization of specimen movements by investigator-1. Static and dynamic system calibration was performed prior to collecting CIDP measurements. A custom-made four cluster marker with 6-inch post was mounted into a pre-drilled location in the zygomatic bone (Fig. 3).³⁷ The OptiTrack provided real-time tri-planar motion feedback to investigator-1, ensuring isolated sagittal plane movements. Investigator-1 clinical experience determined end-range during the first trial and the two-dimensional coordinates of this initial end-range position were noted as a reference for investigator-1 during subsequent trials.

Testing Procedures

Phase 1: CIDP measurements reliability

Five trials of each sagittal plane end-range posture were performed for the first two specimens with mean CIDP calculated.^{7,9,10,12,17,18} This process was repeated three times and reliability calculated for the three measurements. Two investigators performed the data collection. Investigator-1 performed all cervical spine sagittal plane end-range postures using an empirical approach of pressure used in clinical practice (Fig. 4). Investigator-1 was blinded to all CIDP measurements throughout testing. Investigator-2 recorded all CIDP readings for each cervical IVD level (C4-5; C5-6 and C6-7) and monitored results for IVD pressure loss indications requiring system reloading or needle flushing. Measurement order for each end-range posture was randomly assigned using an analog randomization technique. The same order of measurements was used on all three rounds of reliability testing. Successive testing rounds were repeated 30 minutes after previous data collection completion.

Phase 2: CIPD measurements

The end-range posture testing order was randomly assigned by investigator-2 as previously reported. After IVD probe placement, cadavers remained in supine with table edge at the second thoracic spinous process, head on removable support table, straps at waist and chest. Neutral head position was achieved mid-range between cervical flexion and extension.^7,32 Investigator-1 performed each cervical spine sagittal plane end-range postures five repetitions with investigator-2 monitoring pressure responses of specimens during testing.^{7,9,10,12,17,18} Investigator-1 remained blinded to CIDP measurements obtained during neutral and end-range postures while Investigator-2 recorded CIDP measurements for each end-range posture during the five trials.

Phase 3: CIDP and Segmental Cervical ROM Correlation

Segmental cervical spine angular ROM was measured at C4-5, C5-6, and C6-7 for all end-range postures for each cadaveric specimen from digital lateral radiograph images. Measurements were performed using open-source software program ImageJ (Wayne Rasband and contributors, National Institutes of Health, Bethesda, Maryland, USA). Segmental ROM for IVD levels were measured by anterior disc space angles at neutral and each end-range posture. Tangential lines were drawn at inferior endplates of superior vertebrae and superior endplates of inferior vertebrae. Angles created by tangential lines for each IVD segment were measured for all specimens at each end-range posture and neutral cervical spine using the modified Cobb angle method to determine anterior disc space angle.^38,39 Intra-rater reliability was determined for investigator-1 by three segmental ROM measurements at C4-5, C5-6, and C6-7 from two specimens completed over three separate days. Segmental ROM and CIDP measurements for each end-range posture were correlated to identify potential associations.

Statistical Analyses

Descriptive statistics including mean, median, standard deviation, minimum and maximum values for specimen demographics including age, gender, height, weight, and body mass index were calculated and reported above. Descriptive statistics of CIDP for all cervical end-range postures at each IVD level are presented in Table 1.

Table 1

End-range CIDP (mm Hg) means, standard deviations, median, and interquartile range at each IVD level.
Posture	Statistics	C4-5	C5-6	C6-7
Chin to Neck	Mean±SD	25.59±44.49	40.62±87.39	9.71±26.58
	Median	3.23	0.26	0.25
	IQR	52.23	95.76	4.81
Chin to Sternum	Mean±SD	104.07±245.61	52.80±69.63	32.55±47.85
	Median	7.77	22.18	15.16
	IQR	26.78	137.08	32.38
Protraction-Flexion	Mean±SD	61.84±249.68	-69.84±130.48	-30.25±71.28
	Median	-7.16	-17.38	-0.61
	IQR	22.80	83.69	34.61
Occiput to Neck	Mean±SD	28.65±37.48	-15.00±100.02	-1.73±8.84
	Median	4.35	-0.50	-0.33
	IQR	78.51	42.10	10.91
Occiput to Thorax	Mean±SD	8.04±75.59	-98.99±132.64	-3.40±32.00
	Median	-0.55	-21.50	-5.99
	IQR	26.14	279.74	36.99
Retraction-Extension	Mean±SD	26.01±73.78	-103.45±129.90	-16.85±36.07
	Median	9.50	-13.65	-4.97
	IQR	109.47	236.07	67.77
Traction	Mean±SD	-51.13±68.41	-101.45±168.12	-45.69±60.61
	Median	-31.40	-9.12	-31.99
	IQR	86.98	238.68	64.05

CIDP = Cervical intradiscal pressure; IVD = intervertebral disc; IQR = interquartile range; positive numbers indicate increased CIDP while negative numbers indicate decreased CIDP.

Inferential statistics were calculated using the IBM SPSS Statistics, Version 27 (IBM Corporation, New Orchard Road, Armonk, NY 10504). Intraclass correlation coefficient [ICC (3, 5)] was measured using mean CIDP changes from the five consecutive measurements of each end-range posture at each of the three cervical IVD levels. The CIDP data did not meet assumptions for parametric statistics for normal distribution, therefore multiple Friedman two-way ANOVAs were used to evaluate main effects in CIDP differences during various end-range cervical postures for C4-5, C5-6 and C6-7. Post hoc analyses were performed with Dunn’s pairwise comparisons to assess for significant differences in CIDP between each end-range posture for each cervical IVD level. Alpha level was adjusted using Bonferroni correction to < .002 for multiple comparisons. The effect size of end-range postures on CIDP for each IVD level was calculated by Kendall’s W. Intra-rater reliability of segmental cervical spine angular ROM measurements was performed by ICC (3, 1). Spearman rank correlation was performed on CIDP and cervical ROM by IVD level for each end-range posture to identify any association between measures.

Phase 1 of our study sought to establish the intra-rater reliability of CIDP measurements and resulted in an ICC (3, 5) greater than .92 (95% confidence interval = .86-.95).

Phase 2 explored the effect of end-range sagittal plane postures on CIDP relevant to the C4-5, C5-6, and C6-7 IVDs using Friedman ANOVAs with results indicating that end-range postures effected changes in CIDP for each IVD level. Pairwise comparisons showed significant CIDP increases from C4-5 traction to chin to sternum (p = .011); C5-6 traction to chin to sternum (p = .007); C5-6 chin to sternum to retraction-extension (p = .027); C5-6 chin to sternum to protraction flexion (p = .042); C6-7 chin to sternum to traction (p = .018); and C6-7 chin to sternum to retraction-extension (p = .027). When considering prevalence of increased CIDP across each end-range posture at all IVD levels, CIDP increased 71% of the time during chin to neck, 100% during chin to sternum, 38% during protraction-flexion, 48% during occiput to neck, 33% during occiput to thorax, 38% during retraction-extension, and 0% during traction. Moderate effect sizes of end-range postures on CIDP at each IVD level were determined by Kendall’s Coefficient of Concordance with .31 at C4-5, .46 at C5-6, and .36 at C6-7.

In Phase 3, the intra-rater reliability of radiographic angular measures of segmental cervical spine ROM resulted in an ICC(3, 1) greater than .96 (95% confidence interval = .94-.98). Although ROM data did meet assumptions for normality, CIDP did not display a normal distribution, thus the Spearman rank correlation was calculated. Strong correlations between end-range posture and CIDP were identified at C4-5 chin to neck, r_S=.79, p = .04, where cervical flexion and CIDP increased; C5-6 occiput to thorax, r_S=.79, p = .04, where cervical flexion and CIDP decreased; and C6-7 protraction flexion, r_S=.82, p = .02, where cervical flexion increased and CIDP decreased. Expected positive and negative correlations were not found in many of the end-range conditions, including C6-7 protraction flexion. These results may be attributed to outliers created by the wide CIDP variations observed within and between specimens. Segmental cervical spine angular ROM and correlation details are presented in Table 2.

Table 2

End-range cervical angular ROM (degrees) means, standard deviations, range, CIDP correlation and significance per IVD.
Posture	Statistics	C4-5	C5-6	C6-7
Neutral Posture	Mean±SD	11.44±2.13	10.17±3.23	5.59±3.96
Neutral Posture	Range	7.93 to 14.68	4.71 to 13.32	2.32 to 14.04
Mean Differences from Neutral Posture
Chin to Neck	Mean±SD	-4.37±4.98	-5.48±4.24	0.33±3.38
	Range	-9.37 to 4.77	-9.56 to 2.20	-4.01 to 5.13
	Spearman	r_s=0.79, p = .04	r_s=0.18, p = .70	r_s=0.07, p = .88
Chin to Sternum	Mean±SD	-6.84±2.92	-5.85±2.57	-1.78±4.80
	Range	-11.56 to -2.49	-9.09 to -2.04	-10.11 to 2.08
	Spearman	r_s=-0.32, p = .48	r_s=-0.11, p = .82	r_s=-.36, p = .43
Protraction-Flexion	Mean±SD	-6.65±2.96	-6.58±2.36	-1.89±3.43
	Range	-11.58 to -3.86	-9.93 to -4.12	-9.04 to 1.89
	Spearman	r_s=0.18, p = .70	r_s=-0.14, p = .76	r_s=0.82, p = .02
Occiput to Neck	Mean±SD	-0.05±4.01	0.29±5.91	2.04±3.76
	Range	-7.61 to 3.96	-5.98 to 9.13	-3.51 to 8.94
	Spearman	r_s=-0.21, p = .65	r_s=0.29, p = .54	r_s=0.50, p = .25
Occiput to Thorax	Mean±SD	3.94±4.35	2.03±5.43	3.73±4.54
	Range	-1.86 to 10.92	-2.58 to 11.34	-3.03 to 9.74
	Spearman	r_s=-0.25, p = .59	r_s=0.79, p = .04	r_s=0.43, p = .34
Retraction-Extension	Mean±SD	2.12±3.82	1.50±6.86	4.16±4.64
	Range	-2.07 to 8.77	-6.71 to 11.35	-4.18 to 9.68
	Spearman	r_s=0.14, p = .76	r_s=0.50, p = .25	r_s=0.71, p = .07

CIDP = cervical intradiscal pressure IVD = intervertebral disc; ROM = range of motion; r_s=Spearman rank correlation, bold indicates significant values; values represent disc space angle between adjacent vertebral endplates; negative numbers represent decreased angles relative to neutral posture indicating flexion; positive numbers represent increased angles relative to neutral posture indicating extension.

Our study was the first to evaluate effects of supine sagittal plane end-range cervical postures including protraction and retraction on CIDP. Results indicated that CIDP was highly variable within and between cadaveric specimens. This is consistent with previous studies demonstrating wide ranging CIDP values from 700 mm Hg in cervical extension⁷ to 7978 mm Hg during cervical flexion and extension movements¹⁴ with greater unpredictability with concomitant cervical IVD degeneration. The CIDP measurements in our study also ranged widely from − 188 to 660 mm Hg at C4-5, -427 to 216 mm Hg at C5-6, and − 189 to 138 mm Hg at C6-7. Several factors may be contributing to overall lower CIDP measurements recorded in our study compared to those reported in previous investigations. First, the mean age of our specimens was 80.6 years, increasing the likelihood of degenerative cervical IVDs. Kambin et al.,²⁷ Menkowitz et al.¹⁶ and Hattori et al.²⁸ demonstrated decreased CIDP in subjects with IVD degeneration. Hattori et al.²⁸ detailed the unpredictability of peak CIDP during varied cervical ROM, even citing flexion causing negative CIDP. Instrumentation for measuring CIDP varies widely across the limited studies examining cervical IVDs. Most other studies included some degree of axial compression and vertical postures, which resulted in increased CIDP,^{7,9,10,13,18–20} whereas our study was performed in supine without axial loading to simulate clinical conditions.

Our results demonstrated highest CIDP during flexion movements and decreased CIDP during extension and was consistent with the findings of Pospiech et al.¹⁰ and Wu et al.⁶ Additionally, Pospiech et al.¹⁰ identified that proximal IVDs, C3-4 in their study, yielded higher CIDP both in flexion and extension ROM, which was reflected in our study with C4-5 tending to display higher CIDP in all end-range sagittal postures than C5-6 and C6-7.¹⁰ Further support of increased CIDP during flexion, decreased CIDP during extension, and decreasing CIDP in the caudal direction of IVD segments was reported by Liebsch and Wilke⁴⁰ in their systematic review and meta-analysis of whole spine intradiscal pressures.

Two cervical postures were consistent for CIDP changes. Cervical traction resulted in decreased CIDP while chin to sternum increased CIDP in all cadaveric specimens at C4-5, C5-6 and C6-7. Cervical traction CIDP reductions were consistent with Gudavalli et al.,¹⁵ Li et al.,²⁹ and Wu et al.,⁶ while increased CIDP in cervical flexion posture was supported by the findings of Pospiech et al.¹⁰ and Wu et al.⁶ Our findings differed from the results of Hattori et al.,²⁸ Eck et al.,⁷ and Park et al.,⁹ who reported cervical extension movements increased CIDP greater than cervical flexion. Thus, uncertainty remains about sagittal plane direction impact on CIDP.

Although not statistically significant, a greater percentage of specimens experienced decreased CIDP in protraction (57% at C4-5, 71% at C5-6, and 57% at C6-7), retraction (71% at C5-6 and C6-7), occiput to neck (57% at C5-6 and 57% at C6-7) and occiput to thorax (57% at C4-5, 71% at C5-6 and C6-7), while CIDP increased in a majority of specimens during chin to neck (86% at C4-5, 71% at C5-6, and 57% at C6-7). The exception to the rule was C4-5, which demonstrated increased CIDP during occiput to neck (57%) and retraction (57%).

Clinically, our findings showed large CIDP variability in response to sagittal plane end-range postures and suggest emphasizing patient response to evaluative or treatment interventions. Tendencies for CIDP to decrease during extension movements were supported at C5-6 and C6-7, while C4-5 remained less predictable in CIDP responses. Full cervical flexion attained through chin to sternum motion consistently increased CIDP and should be avoided in patients with symptoms and findings consistent with IVD pathology. In contrast, cervical traction decreased CIDP regardless of IVD level and could be an effective treatment tool aimed at decreasing CIDP for IVD pathology. The use of cervical retraction to treat individuals with cervical IVD conditions is best assessed by patient response, due to variable CIDP responses at C4-5 and decreases at C5-6 and C6-7. Much concern is directed at the long-term consequences of protracted cervical postures during human-device interfaces; however, CIDP tended to decrease at all IVD levels during end-range protraction despite similar segmental ROM to chin to sternum postures. Again, patient response to various postures should be the primary determinant on addressing modifications for cervical IVD conditions.

Several limitations exist that affect the application of our results to direct clinical practice. The small sample size is a limitation with regard to the statistical power of the study; however, moderate effect sizes were demonstrated with respect to the significant end-range postures on CIDP. As with all cadaveric studies, direct correlation with live patient care is not possible. Specimens are limited in physiological responses to tissue loading and testing and ignores the contribution of contractile elements on CIDP and ROM.

Our study measured CIDP with all specimens in the supine position and was consistent with procedures in Hattori et al.’s²⁸ in vivo study of cervical IVDs prior to surgical intervention as well as the two traction studies by Gudavalli et al.¹⁵ and Wu et al.⁶ Future studies should evaluate the effects of end-range postures in the sagittal plane on CIDP in weight bearing positions, such as sitting or standing to address the additional effects of axial loading secondary to the weight of the head and gravitational forces, as well as examining responses to axial rotation and lateral bending. Supplementary areas to explore would be the addition of MRI and diagnostic ultrasound to correlate imaging findings with CIDP.

This is the first research study to examine CIDP during supine sagittal plane end-range postures, including retraction and protraction, similar to clinical evaluation and treatment approaches. Increasing our understanding of CIDP responses during daily activities, manual techniques, and exercise interventions will contribute to improved outcomes for cervical IVD pathologies. With that goal in mind, we found consistently decreased CIDP at C4-5, C5-6 and C6-7 during cervical traction while CIDP increased during chin to sternum postures. Supine cervical IVD responses were widely variable with regard to magnitude and direction of CIDP values during chin to neck, protraction, occiput to neck, occiput to thorax, and retraction. Increased CIDP tended to occur during chin to neck postures and then demonstrated decreasing trends during protraction, occiput to neck, occiput to thorax and retraction.

CIDP - cervical intradiscal pressure

IVD(s) - intervertebral disc(s)

ROM - range of motion

Ethics approval and consent to participate: This study protocol was approved by research standards of the département d’anatomie à l’Université du Québec à Trois-Rivières Ethics Subcommittee for the use of cadaveric material (SCELERA-21-06). Consent for participation in the body donation program for teaching and research at the Université du Québec à Trois-Rivières was provided by all donors or their family members in the presence of two witnesses according to the government of Québec Ministère de la Santé et des Services sociaux guidelines.

Consent for publication: Not applicable.

Availability of data and materials: The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.

Competing interests: The authors declare that they have no competing interests.

Funding: Not applicable

Authors' contributions: The roles of each author are detailed below according to the Contributor Roles Taxonomy (CRediT).

MTC – conceptualization, data and curation, formal analysis, investigation, methodology, validation, visualization, writing – original draft, writing – review and editing
JMB – conceptualization, formal analysis, methodology, project administration, supervision, writing – review and editing
MOSP – investigation, methodology
NB – investigation
PSS – conceptualization, methodology, supervision, writing – review and editing
SS – conceptualization, investigation, methodology, project administration, resources, supervision, writing – review and editing

Acknowledgements: The authors thank the team of the anatomy laboratory of the Université du Québec à Trois-Rivières for their support and the use of their facilities and equipment. The authors also sincerely thank those who donated their bodies to science so that anatomical research could be performed. These donors and their families deserve our highest gratitude.

Kwak SY, Chang MC. Effect of intradiscal pulsed radiofrequency on refractory chronic discogenic neck pain: A case report. Medicine (Baltimore). 2018;97:e0509.
Lee H, Nicholson LL, Adams RD. Cervical Range of Motion Associations With Subclinical Neck Pain. Spine (Phila Pa 1976). 2003;29:33-40.
Manchikanti L, Helm S, Singh V et al. An algorithmic approach for clinical management of chronic spinal pain. Pain Physician. 2009;12:E225-64.
Onyewu O, Manchikanti L, Falco FJ et al. An update of the appraisal of the accuracy and utility of cervical discography in chronic neck pain. Pain Physician. 2012;15:E777-806.
Tsao S, Pidcoe P. The management of a patient with a cervical disc herniation: a case report. Clin Med Case Rep. 2008;1:45-49.
Wu LP, Huang YQ, Zhou WH et al. Influence of cervical spine position, turning time, and cervical segment on cadaver intradiscal pressure during cervical spinal manipulative therapy. J Manipulative Physiol Ther. 2012;35:428-436.
Eck JC, Humphreys C, Lim T-H, et al. Biomechanical Study on the Effect of Cervical Spine Fusion on Adjacent-Level Intradiscal Pressure and Segmental Motion. Spine (Phila Pa 1976). 2002;27:2431-2434.
Grubb SA, Kelly CK. Cervical discography: clinical implications from 12 years of experience. Spine (Phila Pa 1976). 2000;25:1382-1389.
Park D-H, Ramakrishnan P, Cho T-H et al. Effect of lower two-level anterior cervical fusion on the superior adjacent level. J Neurosurg Spine. 2007;7:336-340.
Pospiech J, Stolke D, Wilke HJ, Claes LE. Intradiscal pressure recordings in the cervical spine. Neurosurgery. 1999;44:379-84; discussion 384.
Singh V. The role of cervical discography in interventional pain management. Pain Physician. 2004;7:249-255.
Chang UK, Kim DH, Lee MC, Willenberg R, Kim SH, Lim J. Changes in adjacent-level disc pressure and facet joint force after cervical arthroplasty compared with cervical discectomy and fusion. J Neurosurg Spine. 2007;7:33-39.
Cripton PA, Dumas GA, Nolte LP. A minimally disruptive technique for measuring intervertebral disc pressure in vitro: application to the cervical spine. J Biomech. 2001;34:545-549.
Dmitriev AE, Cunningham BW, Hu N, Sell G, Vigna F, McAfee PC. Adjacent level intradiscal pressure and segmental kinematics following a cervical total disc arthroplasty: an in vitro human cadaveric model. Spine (Phila Pa 1976). 2005;30:1165-1172.
Gudavalli MR, Potluri T, Carandang G, et al. Intradiscal Pressure Changes During Manual Cervical Distraction: A Cadaveric Study. Evid Based Complement Alternat Med. 2013; Article ID 954134.
Menkowitz M, Stieber JR, Wenokor C, Cohen JD, Donald GD, Cresanti-Dakinis C. Intradiscal pressure monitoring in the cervical spine. Pain Physician. 2005;8:163-166.
Kretzer RM, Hsu W, Hu N et al. Adjacent-level range of motion and intradiscal pressure after posterior cervical decompression and fixation: an in vitro human cadaveric model. Spine (Phila Pa 1976). 2012;37:E778-85.
Lou J, Li Y, Wang B, Meng Y, Gong Q, Liu H. Biomechanical evaluation of cervical disc replacement with a novel prosthesis based on the physiological curvature of endplate. J Orthop Surg Res. 2018;13:41.
Rao RD, Wang M, McGrady LM, Perlewitz TJ, David KS. Does anterior plating of the cervical spine predispose to adjacent segment changes. Spine (Phila Pa 1976). 2005;30:2788-92; discussion 2793.
Wigfield CC, Skrzypiec D, Jackowski A, Adams MA. Internal stress distribution in cervical intervertebral discs: the influence of an artificial cervical joint and simulated anterior interbody fusion. J Spinal Disord Tech. 2003;16:441-449.
Cuéllar JM, Lanman TH. “Text neck”: an epidemic of the modern era of cell phones. Spine J. 2017;17:901-902.
Mingels S, Dankaerts W, van Etten L, Thijs H, Granitzer M. Comparative analysis of head-tilt and forward head position during laptop use between females with postural induced headache and healthy controls. J Bodyw Mov Ther. 2016;20:533-541.
Park SH. Kinematic analysis of the lower cervical spine in the protracted and retracted neck flexion positions. J Phys Ther Sci. 2015;27:135-137.
Lentell G, Kruse M, Chock B, Wilson K, Iwamoto M, Martin R. Dimensions of the cervical neural foramina in resting and retracted positions using magnetic resonance imaging. J Orthop Sports Phys Ther. 2002;32:380-390.
Ordway NR, Seymour RJ, Donelson RG, Hojnowski LS, Edwards WT. Cervical flexion, extension, protrusion, and retraction. A radiographic segmental analysis. Spine (Phila Pa 1976). 1999;24:240-247.
Takasaki H, Herbowy S. Immediate improvement in the cranio-cervical flexion test associated with MDT-based interventions: a case report. J Man Manip Ther. 2016;24:285-292.
Kambin P, Abda S, Kurpicki F. Intradiskal pressure and volume recording: evaluation of normal and abnormal cervical disks. Clin Orthop Relat Res. 1980;144-147.
Hattori S, Oda H, Kawai S, Ube-Shi. Cervical Intradiscal Pressure in Movements and Traction of the Cervical Spine. Z Orthop Ihre Grenzgeb. 1981;119(6):568-569.
Li YK, Zhu QA, Zhong SZ. The effect of cervical traction combined with rotatory manipulation on cervical nucleus pulposus pressures. J Manipulative Physiol Ther. 1998;21:97-100.
Persson PR, Hirschfeld H, Nilsson-Wikmar L. Associated sagittal spinal movements in performance of head pro- and retraction in healthy women: a kinematic analysis. Man Ther. 2007;12:119-125.
Thoomes-de Graaf M, Thoomes E, Fernández-de-Las-Peñas C, Plaza-Manzano G, Cleland JA. Normative values of cervical range of motion for both children and adults: A systematic review. Musculoskelet Sci Pract. 2020;49:102182.
Hwang H, Hipp JA, Ben-Galim P, Reitman CA. Threshold cervical range-of-motion necessary to detect abnormal intervertebral motion in cervical spine radiographs. Spine (Phila Pa 1976). 2008;33:E261-7.
Bontrager KL, Lampignano J. Chapter 6 Rachis. Bontrager’s handbook of radiographic positioning and techniques. French edition. Elsevier Health Sciences; 2013:188.
Carse B, Meadows B, Bowers R, Rowe P. Affordable clinical gait analysis: an assessment of the marker tracking accuracy of a new low-cost optical 3D motion analysis system. Physiotherapy. 2013;99(4):347-351.
Thewlis D, Bishop C, Daniell N, Paul G. Next-generation low-cost motion capture systems can provide comparable spatial accuracy to high-end systems. J Appl Biomech. 2013;29(1):112-117.
Aurand AM, Dufour JS, Marras WS. Accuracy map of an optical motion capture system with 42 or 21 cameras in a large measurement volume. J Biomech. 2017;58:237-240.
Milner CE. Motion analysis using on-line systems. In: Payton CJ, Burden A, eds. Biomechanical Evaluation of Movement in Sport and Exercise: The British Association of Sport and Exercise Sciences Guide. Second Edition. Abingdon, Oxon: Routledge; 2018:69-90.
Shin DA, Yi S, Yoon DH, Kim KN, Shin HC. Artificial disc replacement combined with fusion versus two-level fusion in cervical two-level disc disease. Spine. 2009;34(11):1153-1159.
Shi S, Zheng S, Li X-F, Yang L-L, Liu Z-D, Yuan W. Comparison of 2 Zero-Profile Implants in the Treatment of Single-Level Cervical Spondylotic Myelopathy: A Preliminary Clinical Study of Cervical Disc Arthroplasty versus Fusion. PLoS One. 2016;11(7):e0159761
Liebsch C, Wilke HJ. The effect of multiplanar loading on the intradiscal pressure of the whole human spine: systematic review and meta-analysis. Eur Cell Mater. 2021;41:388-400.

No competing interests reported.

Download PDF

Editorial decision: Revision requested
06 Aug, 2024
Editor assigned by journal
04 Aug, 2024
Submission checks completed at journal
04 Aug, 2024
First submitted to journal
31 Jul, 2024

You are reading this latest preprint version

Cervical Intradiscal Pressure Responses to End-Range Supine Postures: A Cadaveric Investigation

Status:

Version 1

Abstract

Figures

BACKGROUND

METHODS

Research Design

Specimens and Sample Size

Preparatory Procedures

Instrumentation

Testing Procedures

Phase 3: CIDP and Segmental Cervical ROM Correlation

Statistical Analyses

RESULTS

DISCUSSION

CONCLUSION

Abbreviations

Declarations

References

Additional Declarations

Status:

Version 1