Reliability of lateral bending and axial rotation with validity of a new method to determine axial rotation on anteroposterior cervical radiographs.

OBJECTIVE: To investigate the reliability of a new radiographic measurement of axial rotation and lateral bending on anterior-posterior cervical views by using a computer and sonic digitizer. DESIGN: A blind, repeated-measure design was used. Anteroposterior cervicothoracic radiographs were presented to each of 3 examiners in random order. Each film was digitized, and 1 week later the films were randomized for a second run. SETTING: Private, primary-care chiropractic clinic. MAIN OUTCOME MEASURES: The interclass and intraclass correlation coefficients (ICC) for intraexaminer and interexaminer reliability were calculated from measurements on radiographs for determining axial rotations (Ry) and lateral bending (Rz) of C3 to T3. RESULTS: When the new axial rotation method was applied to small rotations of a C3 plastic model, the average error was less than 1 degrees. For the calculations of axial rotation (Ry), the ICC values were in the good to excellent range. For axial rotation, the intraclass correlation coefficients were ICCs > or =0.78, and the interclass correlation coefficients were ICCs > or =0.67. For lateral flexions (Rz) of C3 to T3, all intraclass and interclass correlation coefficients were in the excellent range (ICCs > 0.87). CONCLUSIONS: Methods of calculating axial rotations in the spine have been reported for large angles (5 degrees to 30 degrees ) but not for smaller angles. A new method for determining axial rotations of the cervical segments on AP views, based on the chord across the arc displaced by the spinous-lamina junction, had reliability (ICC values) in the good to excellent range. Compared with measured rotations of a C3 model (-5 degrees to +5 degrees ), the new method had an average error of less than 1 degrees and approximately 11.5%. The reliability for the axial rotation measurements was in the good to excellent range, and the lateral bending measurements were all in the excellent range.

Chiropractic biophysics digitized radiographic mensuration analysis of the anteroposterior cervicothoracic view: a reliability study.

OBJECTIVE: To investigate the reliability of a radiographic measurement procedure that uses a computer and sonic digitizer to determine projected spinal displacements from an ideal, normal position. DESIGN: A blind, repeated-measure design was used. Anteroposterior cervicothoracic spine radiographs were presented in random order to each of 3 examiners. Each film was digitized, and the films were randomized for a second examination. SETTING: Private, primary care chiropractic clinic. MAIN OUTCOME MEASURES: Intraclass correlation coefficients for intraexaminer and interexaminer reliability for measures on radiographs comparing the perpendicular distance (T(x)) from a vertical axis line drawn through the center of T4 and the center of C2, the linear distance (vertebra(apex)) from the center of the vertebra most displaced from a line connecting the centers of C2 and T4, the angle (Rz) formed by the intersection of the vertical axis line and the upper thoracic line, and the angle of intersection (CDA) between the upper thoracic line and the cervical line. RESULTS: Intraexaminer reliability for T(x) distance was 0.99 to 1.00, with confidence intervals from 0.98-1.00; for vertebra(apex) was 0.96 to 0.97, with confidence intervals from 0.92-0.98; for Rz was 0.94 to 0.98, with confidence intervals from 0. 89-0.99; and for CDA was 0.92 to 0.95, with confidence intervals from 0.84-0.97. Interexaminer reliabilities for the 3 examiners ranged from 0.97 to 0.99. CONCLUSIONS: Measures similar to those described in this study are commonly used to quantify and categorize spinal displacements from true vertical alignment (i.e., scoliosis measurements). Intraclass correlation coefficient values >0.70 are considered accurate enough for use in clinical and research applications. The measures tested here would fit within these guidelines of reliability. Establishing reliability is an important first step in evaluating these measures so that future studies of validity may be undertaken.

Bioavailability of iron in two prenatal multivitamin/multimineral supplements.

OBJECTIVE: To determine the iron bioavailability in two popular prenatal multivitamin/multimineral supplement tablets containing 27 mg elemental iron. STUDY DESIGN: Iron absorption during an eight-hour period following ingestion of a multivitamin/multimineral formulation, both fasting and with a standardized meal, was measured in a group of 30 pregnant women (24-32 weeks of gestation) and statistically compared. The prenatal formulations were Stuartnatal Plus and Materna (Wyeth-Ayerst Pharmaceuticals, Philadelphia, Pennsylvania), and each contains 27 mg of elemental iron. A placebo was included in the study for the control group in this crossover, single-blind study. RESULTS: The net iron bioavailability (mean +/- SE) of Stuartnatal Plus and Materna, accounting for diurnal variation, and the iron ingested with the standardized meal was 5.4 +/- 0.4 and 4.6 +/- 0.2 mg, respectively, while fasting and 2.9 +/- 0.4 and 2.7 +/- 0.4 mg, respectively, postprandially. The total amount of iron absorption in the fasting states from both prenatal formulations exceeded the 3 mg of supplemental iron absorption per day recommended by the National Academy of Sciences. CONCLUSION: The results of this study indicate that these two prenatal multivitamin/multimineral formulations provide > 3.0 mg of supplemental iron absorption (fasting) as recommended by the National Academy of Sciences and 2.7 mg of iron absorption above the levels achieved following ingestion of a standard, low-iron test meal.

Sitting biomechanics, part II: optimal car driver's seat and optimal driver's spinal model.

BACKGROUND: Driving has been associated with signs and symptoms caused by vibrations. Sitting causes the pelvis to rotate backwards and the lumbar lordosis to reduce. Lumbar support and armrests reduce disc pressure and electromyographically recorded values. However, the ideal driver's seat and an optimal seated spinal model have not been described. OBJECTIVE: To determine an optimal automobile seat and an ideal spinal model of a driver. DATA SOURCES: Information was obtained from peer-reviewed scientific journals and texts, automotive engineering reports, and the National Library of Medicine. CONCLUSION: Driving predisposes vehicle operators to low-back pain and degeneration. The optimal seat would have an adjustable seat back incline of 100 degrees from horizontal, a changeable depth of seat back to front edge of seat bottom, adjustable height, an adjustable seat bottom incline, firm (dense) foam in the seat bottom cushion, horizontally and vertically adjustable lumbar support, adjustable bilateral arm rests, adjustable head restraint with lordosis pad, seat shock absorbers to dampen frequencies in the 1 to 20 Hz range, and linear front-back travel of the seat enabling drivers of all sizes to reach the pedals. The lumbar support should be pulsating in depth to reduce static load. The seat back should be damped to reduce rebounding of the torso in rear-end impacts. The optimal driver's spinal model would be the average Harrison model in a 10 degrees posterior inclining seat back angle.

A review of biomechanics of the central nervous system--Part III: spinal cord stresses from postural loads and their neurologic effects.

OBJECTIVE: To review literature pertaining to neurologic disorders stemming from abnormal postures of the spine. DATA COLLECTION: A hand search of available reference texts and a computer search of literature from Index Medicus sources was performed, with special emphasis placed on spinal cord stresses and strains caused by various postural rotations and translations of the skull, thorax, and pelvis. RESULTS: Spinal postures will often deform the neural elements within the spinal canal. Spinal postures can be broken down into four types of loading: axial, pure bending, torsion, and transverse, which cause normal and shear stresses and strains in the neural tissues and blood vessels. Prolonged stresses and strains in the neural elements cause a multitude of disease processes. CONCLUSION: Four types of postural loads create a variety of stresses and strains in the neural tissue, depending on the exact magnitude and direction of the forces. Transverse loading is the most complex load. The stresses and strains in the neural elements and vascular supply are directly related to the function of the sensory, motor, and autonomic nervous systems. The literature indicates that prolonged loading of the neural tissue may lead to a wide variety of degenerative disorders or symptoms. The most offensive postural loading of the central nervous system and related structures occurs in any procedure or position requiring spinal flexion. Thus flexion traction, rehabilitation positions, exercises, spinal manipulation, and surgical fusions in any position other than lordosis for the cervical and lumbar spines should be questioned.

A review of biomechanics of the central nervous system--part II: spinal cord strains from postural loads.

OBJECTIVE: To review spinal cord strains arising from postural loads. DATA COLLECTION: A hand search of available reference texts and a computer search of literature from the Indexed Medicus sources were collected, with special emphasis placed on spinal cord strains caused by various postural rotations and translations of the skull, thorax, and pelvis RESULTS: All spinal postures will deform the neural elements within the spinal canal. Flexion causes the largest canal length changes and, hence, the largest nervous system deformations. Neural tissue strains depend on the spinal level, the spinal movement generated, and the sequence of movements when more than one spinal area is moved. CONCLUSIONS: Rotations of the global postural components (head, thoracic cage, pelvis, and legs) cause stresses and strains in the central nervous system and peripheral nervous system. Translations of the skull, thorax, and pelvis, as well as combined postural loads, need to be studied for their effects on the spinal canal and neural tissue deformations. Flexion of any part of the spinal column may generate axial tension in the entire cord and nerve roots. Slight extension is the preferred position of the spine as far as reducing the magnitude of mechanical stresses and strains in the central nervous system is concerned.

Chiropractic biophysics digitized radiographic mensuration analysis of the anteroposterior lumbopelvic view: a reliability study.

OBJECTIVE: To investigate the reliability of a radiographic measurement procedure that uses a computer and sonic digitizer to determine projected spinal displacements from an ideal normal position. DESIGN: A blind, repeated-measure design was used. Anteroposterior lumbopelvic radiographs were presented to each of 3 examiners in random order. Each film was digitized, and the films were randomized for a second run. SETTING: Private, primary-care chiropractic clinic. MAIN OUTCOME MEASURES: The angle of the sacral base in comparison to a true horizontal line (horizontal base angle), lumbodorsal angle, lumbosacral angle, and the thoracic translational displacement from true vertical determined as the perpendicular distance from the center of T12 to a vertical axis line drawn from the center of the S1 spinous process cephalad and parallel to the lateral edge of the x-ray film. RESULTS: Intraexaminer reliability for the (a) horizontal base angle was .72 to .94, with confidence intervals included in the range of .52 to .97; (b) lumbodorsal angle was .90 to .96, with confidence intervals in the range of .82 to .98; (c) lumbosacral angle was .84 to .96, with confidence intervals in the range of .72 to .98, and (d) thoracic translational displacement from vertical was .95 to.97, with confidence intervals included in the range of .91 to .99. Interexaminer reliability for the three examiners ranged from .71 to .97. CONCLUSIONS: Measures similar to those described in this study are commonly used to measure and categorize spinal displacements from true vertical alignment (ie, scoliosis measurements). Most patient assessment methods used in chiropractic have poor or unknown reliability. The one possible exception to this rule is spinal displacement analysis performed on radiographs. In chiropractic, intraclass correlation coefficients values greater than .70 are considered accurate enough for use in clinical and research applications. The measures tested here would fit within these guidelines of reliability. Establishing reliability is an important first step in evaluating these measures so that future studies of validity may be undertaken.

A review of biomechanics of the central nervous system--Part I: spinal canal deformations resulting from changes in posture.

OBJECTIVE: To discuss how the spinal cord deforms as a result of changes in posture or biomechanical alterations of the spine. DATA COLLECTION: A hand search of available reference texts and a computer search of literature from the Index Medicus sources were collected, with special emphasis placed on spinal canal changes caused by various postural rotations and translations of the skull, thorax, and pelvis. RESULTS: All spinal postures will deform the spinal canal. Flexion causes a small increase in canal diameter and volume as the vertebral lamina are separated. Extension causes a small decrease in canal diameter and volume as the vertebral lamina are approximated. Lateral bending and axial rotation cause insignificant changes in spinal canal diameter and volume in cases without stenosis. CONCLUSIONS: Rotations of the global postural components, head, thoracic cage, and pelvis cause changes in the diameter of the spinal canal and intervertebral foramen. These changes are generally a reduction of less than 1.5 mm in extension, compared with a small increase in flexion of approximately 1 mm. These small changes do not account for the clinical observation of patients having increased neurologic signs and symptoms in flexion.

Low back pain and the lumbar intervertebral disk: clinical considerations for the doctor of chiropractic.

BACKGROUND: Low back pain exists in epidemic proportions in the United States. Studies that demonstrate innervation to the intervertebral disk provide evidence that may account for instances of discogenic low back pain encountered in general medical and chiropractic practice. Many patients and health care practitioners believe that intervertebral disk lesions require surgery as the only method of treatment that will result in satisfactory outcome. Surgery rates vary widely across geographic regions. Only one randomized prospective study exists that compares surgical and nonsurgical treatment; it demonstrated essentially equal outcomes in the long run. OBJECTIVE: To review specific aspects of the examination, history, imaging, and treatment of patients with suspected intervertebral disk lesions and to provide guidelines for conservative management, imaging, and relative and absolute indications for surgical referral. DATA SOURCES: Review articles, texts, and original articles from indexed refereed sources that discuss the lumbar intervertebral disk in regard to patient history, physical examination, imaging, treatment, and referral for surgery. RESULTS: Patients with low back pain who do not present with so-called red flags (fever, history of cancer, unexplained weight loss, urinary tract infection, intravenous drug use, saddle anesthesia, or prolonged use of corticosteroids) may be treated initially with conservative methods. Imaging studies are helpful in determining the patient's diagnosis, and computed tomography, magnetic resonance imaging, or other special imaging studies should be ordered judiciously. The only prospective, randomized study of conservative versus surgical management of herniated lumbar intervertebral disk lesions indicates both methods provide adequate outcome in the long run. Little consensus exists on the best method of management for patients with intervertebral disk lesions without absolute indications for surgery. CONCLUSION: Patients should be screened for "red flags" to determine whether they are candidates for conservative treatment. Magnetic resonance imaging is perhaps the most practical imaging study for evaluation of lumbar disk lesions because it involves no use of ionizing radiation and because magnetic resonance imaging has other advantages over computed tomographic scanning such as excellent delineation of soft tissue structures, direct multiplanar imaging, and excellent characterization of medullary bone. Provocation computed tomography-diskography is an invasive procedure and should be reserved for patients with normal magnetic resonance imaging findings and continuing severe pain who have not been helped by conservative treatment attempts and for whom surgical intervention is contemplated. Both conservative and surgical interventions have been shown to be effective in the treatment of discogenic and radicular pain syndromes.

Sitting biomechanics part I: review of the literature.

OBJECTIVE: To develop a new sitting spinal model and an optimal driver's seat by using review of the literature of seated positions of the head. spine, pelvis, and lower extremities. DATA SELECTION: Searches included MEDLINE for scientific journals, engineering standards, and textbooks. Key terms included sitting ergonomics, sitting posture, spine model, seat design, sitting lordosis, sitting electromyography, seated vibration, and sitting and biomechanics. DATA SYNTHESIS: In part I, papers were selected if (1) they contained a first occurrence of a sitting topic, (2) were reviews of the literature, (3) corrected errors in previous studies, or (4) had improved study designs compared with previous papers. In part II, we separated information pertaining to sitting dynamics and drivers of automobiles from part 1. RESULTS: Sitting causes the pelvis to rotate backward and causes reduction in lumbar lordosis, trunk-thigh angle, and knee angle and an increase in muscle effort and disc pressure. Seated posture is affected by seat-back angle, seat-bottom angle and foam density, height above floor, and presence of armrests. CONCLUSION: The configuration of the spine, postural position, and weight transfer is different in the 3 types of sitting: anterior, middle, and posterior. Lumbar lordosis is affected by the trunk-thigh angle and the knee angle. Subjects in seats with backrest inclinations of 110 to 130 degrees, with concomitant lumbar support, have the lowest disc pressures and lowest electromyography recordings from spinal muscles. A seat-bottom posterior inclination of 5 degrees and armrests can further reduce lumbar disc pressures and electromyography readings while seated. To reduce forward translated head postures, a seat-back inclination of 110 degrees is preferable over higher inclinations. Work objects, such as video monitors, are optimum at eye level. Forward-tilting, seat-bottom inclines can increase lordosis, but subjects give high comfort ratings to adjustable chairs, which allow changes in position.

Further analysis of the reliability of the posterior tangent lateral lumbar radiographic mensuration procedure: concurrent validity of computer-aided X-ray digitization.

OBJECTIVE: To investigate the reliability of a specific method of radiographic analysis of the geometric configuration of the lumbopelvic spine in the sagittal plane, and to investigate the concurrent validity of a computer-aided digitization procedure designed to replace the more tedious and time-consuming manual measurement process. DESIGN: A blind, repeated-measures design was used. The results of radiographic measures derived through the traditional manual marking method were compared with measures derived by computer-aided digitization of lateral lumbopelvic radiographs. SETTING: Private chiropractic clinic. MAIN OUTCOME MEASURES: Pearson's product-moment correlation coefficients, paired sample t tests and intraclass correlation co-efficients (ICC) were used to examine intraexaminer reliability, and repeated measures of analysis of variance were used to examine interexaminer reliability for relative rotation angles for T12-L1, L1-L2, L2-L3, L3-L4, L4-L5, L5-S1, overall lordosis measurement [absolute rotation angle (ARA)] from L1-L5 and Cobb angle of overall lordosis measured from the inferior surface of T12 to the superior surface of S1, Ferguson's sacral base angle to horizontal, angle of pelvic tilt (arcuate angle) to horizontal and anteroposterior thoracic translation (Sz) in millimeters. RESULTS: ICC estimates for intraexaminer reliability were in the range of 0.96-0.98 for the L1-L5 ARA, a range of 0.87-0.99 for the arcuate angle measurement, 0.83-0.94 for the Ferguson's angle measurement, 0.88-0.95 for the Cobb angle measurement from the inferior surface of T12 compared with the superior surface of S1 and 0.98-1.00 for the translation measurement of the lower thoracic spine to S1 (Sz). The intersegmental measurement's (T12-L1, L1-L2, L2-L3, L3-L4, L4-L5, L5-S1) correlations ranged from a low of 0.55 to a high of 0.97. Examination of these findings suggests that the reliability for the three doctors is acceptable with only the T12-L1 intersegmental measure falling below 0.70 for the least experienced examiner. Average ICC of interexaminer reliability for manual and computer-aided digitizing examiners were the following: 0.96 for the L1-L5 ARA; 0.84 for the arcuate angle measurement; 0.82 for the Ferguson's angle measurement; 0.88 for the Cobb angle measurement; 1.00 for the Sz translation measurement; and values of 0.65, 0.73, 0.74, 0.75, 0.89 and 0.81 for relative rotation angle measurements T12-L1, L1-L2, L2-L3, L3-L4, L4-L5 and L5-S1, respectively. CONCLUSION: The data tend to support the reliability of this method of radiographic analysis of the geometric configuration of the lumbopelvic spine as viewed on lateral lumbopelvic radiographs. The additional data presented here tend to support the concurrent validity of the computer-aided digitization method of analysis inasmuch as the measures determined by the digitizing examiners are essentially identical to those determined by the manual method plus or minus the average standard error of measure of each value.

Reliability of spinal displacement analysis of plain X-rays: a review of commonly accepted facts and fallacies with implications for chiropractic education and technique.

BACKGROUND: Current medical, biomechanical, and chiropractic literature indicates that X-ray line drawing analysis for spinal displacement is reliable, with high Interclass Correlation Coefficients (ICCs) found in most studies. Normal sagittal spinal curvatures are being accepted as important clinical outcomes of care; however, just the opposite is taught in many chiropractic college radiology courses. OBJECTIVE: To review the current literature on X-ray line drawing reliability and abnormal static lateral positions. DATA SOURCES: Searches were performed on Medline, Chiro-LARS, MANTIS, and CINAHL on X-ray reliability, normal spinal position, and sagittal spinal curvatures as clinical outcomes. RESULTS: X-ray line drawing analysis for spinal displacement was found to have high reliability with a majority of ICCs in the .8-.9 range. The reliability for determining X-ray pathology was found to be only fair to good by both medical doctors and chiropractors and by both chiropractic and medical radiologists, with a majority of ICCs in the range .40-.75. Muscle spasms, facet hyperplasia, short pedicles and patient positioning errors have not been shown to alter sagittal plane alignment. The sagittal spinal curves are desirable clinical outcomes of care in surgery, physical therapy, rehabilitation and chiropractic. These results contradict common claims found in the indexed literature. CONCLUSION: X-ray line drawing is reliable. Normal values for the sagittal spinal curvatures exist in the literature. The normal sagittal spinal curvatures are important clinical outcomes of care. Patient positioning and postural radiographs are highly reproducible. When these standardized procedures are used, the pre-to-post alignment changes are a result of treatment procedures applied. Chiropractic radiology education and publications should reflect the recent literature, provide more support for X-ray line drawing analyses and applications of line drawing analyses for measuring spinal displacement on plain radiographs.

Three-dimensional spinal coupling mechanics: Part II. Implications for chiropractic theories and practice.

OBJECTIVE: To compare the current knowledge of 3-D spinal mechanics and abnormal equilibrium states with chiropractic motion theories, chiropractic vertebral letter listing theories, and chiropractic technique theories. DATA COLLECTION: A manual search of available reference texts and a computer search of literature from Index Medicus were collected with an emphasis on 3-D studies of human spinal movements, segmental instability, Euler buckling of the spine, and chiropractic theories concerning vertebral movements. RESULTS: Previous spinal coupling results based upon two-dimensional radiographic studies are inadequate and inaccurate. Therefore, the validity of any chiropractic technique procedure, listing, motion analysis or adjusting style based on the two-dimensional radiograph and coupling studies must be questioned. We have identified four types of spinal subluxations (displacements) in the biomechanical literature: (a) posture main motion and associated segmental coupling, (b) Euler buckling viewed in the anteroposterior view, (c) snap through viewed in the lateral view and (d) segmental instability. CONCLUSIONS: Full three-dimensional investigations of spinal coupling patterns have shown that the vertebrae rotate and translate in all three axes and that previous theories of spinal coupling based upon two-dimensional studies are inaccurate and invalid. Previous chiropractic letter listings (e.g., PRI, PLS, etc.) of spinal displacements are inadequate and invalid. Only one of the four types of biomechanical displacements, segmental instability, is consistent with the traditional chiropractic theory of segmental spinal displacements; in general, this does not respond well to care. In general, vertebrae displacement must be viewed in the context of equilibrium configurations and one vertebra can not be displaced as an individual misalignment. Validity questions arise for any technique methods that use letter listings of displacement taken from motion palpation or two-dimensional radiographic analysis.

Three-dimensional spinal coupling mechanics: Part I. A review of the literature.

OBJECTIVE: To determine the state of knowledge relative to three-dimensional spinal coupled motion and to check the validity of currently accepted two-dimensional coupling as taught in chiropractic. DATA COLLECTION: A hand search of available reference texts and a computer search of literature from Index Medicus were collected with an emphasis on three-dimensional studies of human spinal movements. RESULTS: Most postural movements result in complicated three-dimensional spinal coupling in six degrees of freedom. Previous spinal coupling results based upon two-dimensional radiographic studies are inadequate and inaccurate. It is important that chiropractic colleges and techniques use the three-dimensional spinal kinematics to update their curricula and advance chiropractic treatment procedures. CONCLUSION: Full three-dimensional investigations of spinal coupling patterns have shown that the vertebrae rotate and translate in all three axes and that previous theories of spinal coupling based upon two-dimensional studies are inaccurate and invalid. Postural rotations and translations, which are the main motions studied in spinal coupling research, and altered configurations of the normal sagittal plane curves are the cause of both normal and abnormal spinal coupling patterns in three dimensions. Chiropractic letter listings (such as PRS, ASRP, etc.) are outdated, incomplete, invalid representations of coupled segmental movements. Mechanical loading of the neuromusculoskeletal tissues plays a vital role in position, dynamics, proper growth, repair and symptoms. Future studies of spinal kinematics should study the postural translations of the skull and thorax for their associated coupling in three dimensions. Combined postural rotations and translations along with altered sagittal curvatures need to be studied for their associated coupling characteristics as well.

Structural rehabilitation of the spine and posture: rationale for treatment beyond the resolution of symptoms.

OBJECTIVE: To provide a rationale for active chiropractic rehabilitative treatment that extends beyond the single goal of resolution of symptomatic complaints. DATA COLLECTION: A manual search of available reference texts and a search of MEDLINE were collected with an emphasis on tissue healing sequelae and the role of mechanical loading on this process. RESULTS: The reviewed material indicates that all tissue growth and repair is influenced by mechanical loading and body posture and is positively affected by body postures that normalize/minimize adverse mechanical stresses and strains. Altered alignment of the human frame may lead to poor healing of the body tissues and eventual pathological architectural changes may occur in muscle, ligament, bone and central nervous system. Minimization of altered postural/structural loading of the human frame may take longer than resolution, or maximal reduction, of offensive symptoms. By itself, a patient's perception of pain is not a valid indicator of health. CONCLUSION: Because mechanical loading of the neuromusculoskeletal tissues plays a vital role in influencing proper growth and repair, chiropractic rehabilitative care should focus on the normalization/minimization of aberrant stresses and strains acting on spinal tissues. Manipulation alone cannot restore body postures or improve an altered sagittal spinal curve. Therefore, postural chiropractic adjustments, active exercises and stretches, resting spinal blocking procedures, extension traction and ergonomic education are deemed necessary for maximal spinal rehabilitation. Chiropractic studies that demonstrate structural improvements are sorely lacking and needed. The use of passive treatment modalities as the sole means of chiropractic intervention for the management of patients suffering with neuromusculoskeletal dysfunction no longer has a place in modern chiropractic practice after the acute phase of healing has passed.

Evaluation of the assumptions used to derive an ideal normal cervical spine model.

OBJECTIVES: To evaluate the accuracy of anatomical assumptions made to derive a geometrical, ideal, normal model of the upright, static, sagittal cervical spine, to make comparisons with other spinal models and to discuss the implications of a normal cervical model. BACKGROUND: Anatomical assumptions were made based on observations to assist in the development of a computerized geometrical model of the ideal upright, static, sagittal cervical spine. These assumptions address the magnitudes of the contribution made by the vertebral bodies and intervertebral discs to the overall magnitude and geometric shape of the cervical lordosis. STUDY DESIGN: (a) Data were collected from 400 lordotic lateral cervical radiographs and compared with the predictions of a geometric normal cervical lordotic model. Angels of intersecting tangent lines, drawn at posterior vertebral body margins, were measured at each disc space and between C2 and C7. Height-to-length ratios and an anterior weight-bearing distance were measured. (b) LITERATURE REVIEWs were obtained through Medline and Chirolars. RESULTS: (a) Modeling: the 400 sample subjects varied from the geometric model by approximately 5%. Subgroup averages, from partitioning the C2-C7 angle into 5 degrees intervals, were less than 8% in error to model predictions. (b) LITERATURE REVIEW: lordosis is the normal configuration for the cervical spine and many chiropractic empirical models are similar. CONCLUSIONS: The anatomical assumptions used to derive our normal geometric model of the cervical lordosis seem to be supported by the average values and literature reviewed. Two typical geometric configurations of the cervical spine were identified as a normal circular lordotic arc of 34 degrees and an ideal normal of 42 degrees. LITERATURE REVIEWed establishes cervical lordosis as a desirable clinical outcome of care.