Charles N.R. Henderson

A cross-sectional study correlating cervical radiographic degenerative findings to pain and disability.

Study Design A cross‐sectional design was used to correlate cervical radiographic findings of spinal degeneration to neck pain and disability. Objectives The results were correlated to assess the clinical importance of radiographic spinal degeneration. Summary of Background Data Past investigations suggest little association between clinical findings and radiographic evidence of spinal degeneration. However, changes in activities of daily living and chronicity of complaint have not been investigated. Methods Over a 5‐month period, data were collected on 700 consecutive patients referred for cervical radiographic examination as part of their clinical evaluation. While in the radiology department, all subjects completed a visual analog pain scale, neck disability index, and short questionnaire, all of which quantified various aspects of any neck complaint. Relationships between indices of patient complaint and the number of cervical degenerative intervertebral discs were evaluated using regression analysis. Results A significant relationship (P < 0.001) was noted between the number of levels of intervertebral disc degeneration and the chronicity of cervical complaint. No significant relationship was found between cervical degeneration and past trauma (P = 0.904) or gender (P = 0.213). Multiple‐regression analysis of visual analog pain scale scores revealed a significant two‐way interaction with chronicity and past trauma (P = 0.007) and a significant main effect with gender (P < 0.001). Cervical degeneration was not significant as a main effect or interaction with other factors. Multiple‐regression analysis of neck disability index scores demonstrated a significant three‐way interaction of chronicity, degeneration, and gender (P = 0.022) and a significant two‐way interaction for chronicity and trauma (P = 0.025). No additional information was gathered by multivariate multiple‐regression techniques. Conclusions Increasing levels of spinal degeneration are related to increasing chronicity of patient complaints. Spinal degeneration is not related to past trauma or gender. Women, but not men, report higher disability with increasing levels of degeneration. Subjects with past trauma reported more intense pain and disability. Overall, men reported less neck pain and disability than women.

Zygapophyseal joint adhesions after induced hypomobility.

OBJECTIVE Adhesions (ADH) have been previously identified in many hypomobile joints, but not in the zygapophyseal (Z) joints of the spine. The objective of this study was to determine if connective tissue ADH developed in lumbar Z joints after induced intervertebral hypomobility (segmental fixation). METHODS Using an established rat model, 3 contiguous segments (L4, L5, L6) were fixed with specially engineered, surgically implanted, vertebral fixation devices. Z joints of experimental rats (17 rats, 64 Z joints) with 4, 8, 12, or 16 weeks of induced hypomobility were compared with Z joints of age-matched control rats (23 rats, 86 Z joints). Tissue was prepared for brightfield microscopy, examined, and photomicrographed. A standardized grading system identified small, medium, and large ADH and the average numbers of each per joint were calculated. RESULTS Connective tissue ADH were characterized and their location within Z joints described. Small and medium ADH were found in rats from all study groups. However, large ADH were found only in rats with 8, 12, or 16 weeks of experimentally induced intervertebral hypomobility. Significant differences among study groups were found for small (P < .003), medium (P < .000), and large (P < .000) ADH. The average number of medium and large ADH per joint increased with the length of experimentally induced hypomobility in rats with 8 and 16 weeks of induced hypomobility. CONCLUSIONS We conclude that hypomobility results in time-dependent ADH development within the Z joints. Such ADH development may have relevance to spinal manipulation, which could theoretically break up Z joint intra-articular ADHs.

Head repositioning errors in normal student volunteers: a possible tool to assess the neck's neuromuscular system

BackgroundA challenge for practitioners using spinal manipulation is identifying when an intervention is required. It has been recognized that joint pain can interfere with the ability to position body parts accurately and that the recent history of muscle contraction can play a part in that interference. In this study, we tested whether repositioning errors could be induced in a normal population by contraction or shortening of the neck muscles.MethodsIn the experimental protocol, volunteers free of neck problems first found a comfortable neutral head posture with eyes closed. They deconditioned their cervical muscles by moving their heads 5 times in either flexion/extension or lateral flexion and then attempted to return to the same starting position. Two conditioning sequences were interspersed within the task: hold the head in an extended or laterally flexed position for 10 seconds; or hold a 70% maximum voluntary contraction in the same position for 10 seconds. A computer-interfaced electrogoniometer was used to measure head position while a force transducer coupled to an auditory alarm signaled the force of isometric contraction. The difference between the initial and final head orientation was calculated in 3 orthogonal planes. Analysis of variance (1-way ANOVA) with a blocking factor (participants) was used to detect differences in proprioceptive error among the conditioning sequences while controlling for variation between participants.ResultsForty-eight chiropractic students participated: 36 males and 12 females, aged 28.2 ± 4.8 yrs. During the neck extension test, actively contracting the posterior neck muscles evoked an undershoot of the target position by 2.1° (p <0.001). No differences in repositioning were found during the lateral flexion test.ConclusionThe results suggest that the recent history of cervical paraspinal muscle contraction can influence head repositioning in flexion/extension. To our knowledge this is the first time that muscle mechanical history has been shown to influence proprioceptive accuracy in the necks of humans. This finding may be used to elucidate the mechanism behind repositioning errors seen in people with neck pain and could guide development of a clinical test for involvement of paraspinal muscles in cervical pain and dysfunction.

Developing a clinical competency examination in radiology: Part I—Test structure ☆ ☆☆ ★ ★★

BACKGROUND There is a need for radiology educational outcome measures that evaluate clinical competency. This is the first of two articles introducing a clinical competency examination in radiology. This first article describes the evolution and structure of the examination. The second article presents the results of two administrations of the examination and evaluates possible outcome predictors. OBJECTIVE To develop a measure of clinical competency in radiology. DESIGN Descriptive. METHODS A test was developed to simulate the radiologic interpretive skills needed in clinical chiropractic practice. Students were timed as they responded to questions regarding the localization, categorization, management, and identification of pathologic conditions presented on plain film images of the spine and chest. Twenty-five radiographic cases were displayed at individual viewbox stations, and student responses to the 4 questions were compared with the consensus responses of 2 radiology instructors. RESULTS Two versions of the test, using different cases, were given to the same ninth trimester class of 210 chiropractic students in a 10-trimester program. Of the 210 students, 116 (55.2%; 86 men and 30 women) took version 1 of the examination, and 1 month later 181 (86.2%: 138 men and 43 women) took version 2 of the examination. Student comments after each examination were favorable. CONCLUSION The test structure uniquely provides information related to the students ability to localize, categorize, manage, and identify pathologic conditions on imaging studies. At present the examination is instructor time intensive; further refinement is needed before wide implementation can occur.

Introducing the External Link Model for Studying Spine Fixation and Misalignment: Current Procedures, Costs, and Failure Rates

OBJECTIVE This is the last article in a series of 3 articles introducing a new animal model, the external link model (ELM), that permits reversible, nontraumatic control of the cardinal biomechanical features of the subluxation: fixation and misalignment. A detailed description of current ELM procedures is presented and practical issues are reviewed such as expense (dollars and time) and construct failure rates during and after the surgical implant procedure. METHOD Descriptive report of current ELM procedures, refinements to the spinous attachment units (SAUs), and tabulation of costs and failure rates drawn from recent studies. RESULTS In contrast to the older, 1-piece stainless steel SAUs, new 3-piece titanium SAUs may be reimplanted many times without failure. Consequently, the cost per ELM ranges from

Spinous process hypertrophy associated with implanted devices in the external link model.

579 to

Basic science research related to chiropractic spinal adjusting: the state of the art and recommendations revisited.

69, depending on whether the SAUs, links, and screws must be purchased or are already available for implanting. The SAU implant procedure requires between 0.5 and 1.25 hours, depending on the experience of the surgeon. The total construct failure rate for the ELM is 24.2% (6.6% at surgery failure + 17.8% postsurgery failures). This rate is consistent with that reported in spine implant studies with other devices. To date, more than 500 male Sprague-Dawley rats (350-450 g) have been implanted with SAUs for ELM studies at the Palmer Center for Chiropractic Research and the National University of Health Sciences. CONCLUSION It has been our experience that individuals with basic animal research training will become proficient at producing the ELM after observing 3 to 4 implant procedures and performing 4 to 6 procedures on their own.

Degenerative Changes Following Spinal Fixation in a Small Animal Model

OBJECTIVE Recent development of a chiropractic subluxation mimic, the external link model, uses titanium implants on lumbar vertebrae in the rat. The objective of this study was to evaluate potential correlations in the model between linking history, bone resorption, exudate formation, and experimentally induced intervertebral hypomobility. METHODS Serial lateral radiographs of 73 male Sprague Dawley rats with implanted devices were reviewed. A baseline radiograph was obtained after a 6-week surgical recovery period, and a second radiograph was exposed after an 8-week hypomobility induction period. Spinous hypertrophy at the implant sites (L4, L5, and L6) was measured on the radiographs with a vernier caliper. Bone resorption and exudate build-up were assessed and compared with intervertebral hypomobility data previously collected. Data trends were described using cross-tabulated counts, analysis of variance, and regression analysis. RESULTS Cross-tabulation suggested differences between hypomobility-induced rats and control rats. However, correlation analysis showed no predictive role for spinous hypertrophy relative to intervertebral mobility. Similarly, exudate level did not predict spinous hypertrophy. However, implant presence and vertebral level had a significant interaction, with moderate and severe hypertrophy occurring more frequently at L4 and L6 in hypomobility-induced rats. Age did not materially influence spinous hypertrophy. CONCLUSIONS Mechanical stresses produced at the implant bone interface in rats with induced hypomobility contribute to spinous hypertrophy beyond that simply due to the presence of the implants. However, spinous hypertrophy does not contribute significantly to intervertebral hypomobility in the external link model.