Repeatability of Cervical Joint Flexion and Extension Within and Between Days

Evaluation of Apparatus and Protocols to Measure Human Passive Neck Stiffness and Range of Motion

Understanding of human neck stiffness and range of motion (ROM) with minimal neck muscle activation ("passive") is important for clinical and bioengineering applications. The aim of this study was to develop, implement, and evaluate the reliability of methods for assessing passive-lying stiffness and ROM, in six head-neck rotation directions. Six participants completed two assessment sessions. To perform passive-lying tests, the participant's head and torso were strapped to a bending (flexion, extension, lateral bending) or a rotation (axial rotation) apparatus, and clinical bed, respectively. The head and neck were manually rotated by the researcher to the participant's maximum ROM, to assess passive-lying stiffness. Participant-initiated ("active") head ROM was also assessed in the apparatus, and seated. Various measures of apparatus functionality were assessed. ROM was similar for all assessment configurations in each motion direction except flexion. In each direction, passive stiffness generally increased throughout neck rotation. Within-session reliability for stiffness (ICC > 0.656) and ROM (ICC > 0.872) was acceptable, but between-session reliability was low for some motion directions, probably due to intrinsic participant factors, participant-apparatus interaction, and the relatively low participant number. Moment-angle corridors from both assessment sessions were similar, suggesting that with greater sample size, these methods may be suitable for estimating population-level corridors.

Effects of experimental pain on the cervical spine reposition errors

BACKGROUND

Healthy subjects showed normal variance of cervical spine reposition errors of approximately 2 degrees. Effects of experimental pain on cervical spine reposition errors were unknown; thus, the purpose of this study was to investigate the effects of experimental pain on cervical spine reposition errors.

METHODS

A repeated measured study design was applied. Thirty healthy subjects (12 males) were recruited. Reposition errors were extracted from upright cervical positions before and after cervical flexion movement in healthy subjects before and during experimental neck pain. Cervical spine reposition errors were calculated based on anatomical landmarks of each cervical joint. Reposition errors were extracted in degrees as constant errors and absolute errors for further statistical analysis. Repeated measures analysis of variance (RM-ANOVA) was applied to analyse experimental pain effects on either constant errors or absolute errors of different cervical joints.

RESULTS

The cervical spine showed non-significant difference in reposition errors regarding the constant errors (P>0.05) while larger reposition errors regarding the absolute errors during experimental pain compared to before experimental pain (P<0.001). In addition, the pain level joint (C4/C5) and its adjacent joints (C3/C4 and C5/C6) indicated larger reposition errors regarding absolute errors (P=0.035, P=0.329 and P=0.103, respectively).

CONCLUSIONS

This study firstly investigated the cervical spine reposition errors in experimental neck pain and further found the joints adjacent to the pain level showed larger errors compared to the distant joints regarding absolute errors. It may imply that the larger reposition errors in specific cervical joint indicate probable injury or pain existed adjacent to the joints.

The global end-ranges of neck flexion and extension do not represent the maximum rotational ranges of the cervical intervertebral joints in healthy adults - an observational study

Background

In clinical diagnosis, the maximum motion of a cervical joint is thought to be found at the joint’s end-range and it is this perception that forms the basis for the interpretation of flexion/extension imaging studies.

There have however, been representative cases of joints producing their maximum motion before end-range, but this phenomenon is yet to be quantified.

Purpose

To provide a quantitative assessment of the difference between maximum joint motion and joint end-range in healthy subjects. Secondarily to classify joints into type based on their motion and to assess the proportions of these joint types.

Study design

This is an observational study.

Subject sample

Thirty-three healthy subjects participated in the study.

Outcome measures

Maximum motion, end-range motion and surplus motion (the difference between maximum motion and end-range) in degrees were extracted from each cervical joint.

Methods

Thirty-three subjects performed one flexion and one extension motion excursion under video fluoroscopy. The motion excursions were divided into 10% epochs, from which maximum motion, end-range and surplus motion were extracted. Surplus motion was then assessed in quartiles and joints were classified into type according to end-range.

Results

For flexion 48.9% and for extension 47.2% of joints produced maximum motion before joint end-range (type S). For flexion 45.9% and for extension 46.8% of joints produced maximum motion at joint end-range (type C). For flexion 5.2% of joints and for extension 6.1% of joints concluded their motion anti-directionally (type A).

Significant differences were found for C2/C3 (P = 0.000), C3/C4 (P = 0.001) and C4/C5 (P = 0.005) in flexion and C1/C2 (P = 0.004), C3/C4 (P = 0.013) and C6/C7 (P = 0.013) in extension when comparing the joint end- range of type C and type S.

The average pro-directional (motion in the direction of neck motion) surplus motion was 2.41° ± 2.12° with a range of (0.07° -14.23°) for flexion and 2.02° ± 1.70° with a range of (0.04°-6.97°) for extension.

Conclusion

This is the first study to categorise joints by type of motion. It cannot be assumed that end-range is a demonstration of a joint’s maximum motion, as type S constituted approximately half of the joints analysed in this study.

Recurrent neck pain patients exhibit altered joint motion pattern during cervical flexion and extension movements

BACKGROUND

Impaired sensorimotor ability has been demonstrated in recurrent neck pain patients. It is however not clear if cervical joint motion and pressure pain sensitivity in recurrent neck pain patients are different from asymptomatic controls.

METHODS

Cervical flexion and extension motions were examined by video-fluoroscopy and pressure pain thresholds were assessed bilaterally over C2/C3, C5/C6 facet joints and right tibialis anterior in eighteen recurrent neck pain patients and eighteen healthy subjects. Individual joint motion was analyzed by dividing fluoroscopic videos into 10 epochs. The motion opposite to the primary direction (anti-directional motion) and motion along with the primary direction (pro-directional motion) of each joint were extracted across epochs. Total joint motion was the sum of anti-directional and pro-directional motions. Joint motion variability was represented by the variance of joint motions across epochs.

FINDINGS

Compared to controls, recurrent neck pain patients showed: 1) decreased anti-directional motion at C2/C3 and C3/C4 (P < 0.05) and increased anti-directional motion at C5/C6 and C6/C7 (P < 0.05) during extension motion. 2) Increased overall anti-direction motion during flexion motion (P < 0.05). 3) Lower joint motion variability at C3/C4 during extension motion (P < 0.05).

INTERPRETATION

Recurrent neck pain patients showed a redistribution of anti-directional motion between the middle cervical spine and the lower cervical spine during cervical extension and increased overall anti-directional motion during cervical flexion compared with healthy controls. The anti-directional motion was more sensitive to neck pain compared to other cervical joint motion parameters in the present study.

Experimental cervical interspinous ligament pain altered cervical joint motion during dynamic extension movement

BACKGROUND

Although the cervical interspinous ligament is a potential source of neck pain, the effects on cervical joint motion and pressure pain sensitivity has never been investigated. The understanding of the relationship will broaden our understanding of cervical biomechanics and improve diagnosis and treatment of neck pain.

METHODS

Fluoroscopy videos of cervical flexion and extension movements and pressure pain thresholds over bilateral C2/C3 and C5/C6 facet joints were collected in fifteen healthy subjects before and after injections of hypertonic and isotonic saline in C4/C5 ISL. The videos were divided into 10 even epochs and the motion of individual joints during each epoch was extracted. Joint motion parameters including anti-directional motion, pro-directional motion, total joint motion and joint motion variability were extracted across epochs. Joint motion parameters and PPTs were compared before and after injection of hypertonic and isotonic saline separately.

FINDINGS

Compared with baselines: hypertonic saline injection 1) decreased anti-directional motion and joint motion variability at C4/C5 (P < 0.05) and increased at C2/C3 (P < 0.05) during extension; 2) increased total joint motion of C0/C1 during first half range (P < 0.05) and decreased during second half range of extension, and total joint motion of C2/C3 increased during second half range of extension (P < 0.05) and; 3) increased pressure pain thresholds over left C2/C3 facet joint (P < 0.01).

INTERPRETATION

The cervical interspinous ligament pain redistributed anti-directional motion between C4/C5 and C2/C3 during dynamic extension and decreased pressure pain sensitivity over the left C2/C3 facet joint.

Origin of neck pain and direction of movement influence dynamic cervical joint motion and pressure pain sensitivity

BACKGROUND

Patients with neck pain normally showed alterations in cervical motion and pressure pain sensitivity. Cervical joints show scattered motions opposite to (anti-directional) the primary motion direction (pro-directional) during dynamic cervical flexion and extension. This study aimed to assess dynamic cervical joint motion and pressure pain sensitivity when pain originated from different cervical muscles which may have clinical relevance in diagnosis of impairments related with neck pain.

METHODS

Fluoroscopic video recordings of cervical flexion and extension were collected from fifteen healthy subjects before and during hypertonic saline-induced pain in right multifidus and trapezius muscles. Cervical flexion and extension motions were divided into 10 epochs with respect to time. Pro-directional, anti-directional, and total joint motion were extracted across epochs as well as joint motion variability. Pressure pain thresholds (PPTs) were assessed bilaterally over C2/C3 and C5/C6 facet joints.

FINDINGS

Compared with baseline: 1) Multifidus muscle pain increased the C3/C4 anti-directional motion (P < 0.01), decreased the C6/C7 anti-directional motion (P < 0.05) during extension, and redistributed total joint motion between joints and between half ranges during flexion (P < 0.05). 2) Trapezius muscle pain decreased pro-directional motion (P < 0.05), anti-directional motion (P < 0.05), and joint motion variability (P < 0.05) during extension. 3) Trapezius and multifidus muscle pain increased the PPTs bilaterally over C2/C3 and on the left side of C5/C6 facet joints (P < 0.05).

INTERPRETATION

The direction of motion influenced the effects of experimental muscle pain on dynamic cervical joint kinematics, and deep muscle pain showed local effects on individual joints while superficial muscle pain showed global effects spread to all joints.

Motion analysis of the cervical spine during extension and flexion: Reliability of the vertebral marking procedure

Cervical spine motion analysis using videofluoroscopy is currently a technique without a gold standard. We demonstrate the reliability of a rigid and reliable analysis methodology for cervical motion using videofluoroscopic images, representing the entire range of motion during flexion and extension, from the neutral position to the end-range in the sagittal plane. Two researchers with radiography and vertebral marking expertise, and two inexperienced researchers with 10 hours of training manually marked anatomical structures on fluoroscopic images in a procedure designed to control for vertebral rotation around the mid-plane axis. The average marking error across examiners and images was -0.12^∘ (standard deviation: 0.88°), and the intraexaminer error ranged from -1.00^∘ to 1.61° (standard deviation range: 0.27°-1.19°). Our method demonstrated lower errors compared to the higher resolution X-ray studies, and proved that vertebral marking can be performed by persons with no experience in radiographic image analysis.