Where is the Science?
(Editor's note: The following article may be over the top for many readers but I wanted to include it for those more skeptical and/or analytical minded folks. You can also learn more about research projects here.)
Adapted from: POSITION PAPER FOR UPPER CERVICAL CARE
By Kirk Eriksen, D.C.
A thorough understanding of the anatomy, biomechanics and neurophysiology of the upper cervical spine is a prerequisite to be able to appreciate the clinical manifestations of the occipito-atlanto-axial subluxation complex. White and Panjabi describe the upper cervical articulations as “…the most complex joints of the axial skeleton, both anatomically and kinematically.”  The two upper cervical vertebrae differ in shape and function from the remainder of the spine. The configuration of the atlanto(C1) and axial(C2) joints, enables these structures to carry the head and determine its movement. These articulations also provide protection for the intimate neurologic and vascular structures. The atlas and axis are two of the nine atypical vertebrae. The atlas articulation is diarthrodial and is the most freely movable segment in the spine, in relation to C1-C2 rotation and C0-C1 flexion/extension. The occipito(C0)-C1 articulation consists of reciprocally curved superior facets of the lateral masses of the atlas and the ellipsoid synovial joints of the occipital condyles. This articulation allows for primarily flexion-extension motion, with very little rotation or lateral flexion. The atlas vertebra has a condyloid articulation with the axis that allows for 45-50% of rotation in the cervical spine, but the consensus of the studies show that little motion occurs between the atlas and occiput. The small amount of movement that does occur is found at the end point of the range of motion. This is a critical point when discussion is made about the misalignment component of the subluxation.
The neurological dysfunction related to the upper cervical subluxation can be explained by a few different mechanisms. However, it is likely that these mechanisms manifest concurrently in many patients. The two most plausible hypotheses have to do with spinal cord tension and mechanoreceptive dysafferentation. The upper cervical spinal cord is directly attached to the circumference of the foramen magnum, to the second and third cervical vertebrae and by fibrous slips to the posterior longitudinal ligament. Hinson, Grostic and others discuss dissection evidence showing a dural attachment at the atlas level. The uppermost denticulate ligaments are arranged almost horizontally, as compared to the inferiorly angled ligaments found around the rest of spinal cord. The most cephalad ligaments are also thicker and stronger to help anchor the spinal cord around the foramen magnum. These ligaments are so strong that they have been found to sever the upper cervical spinal cord in some cases of hydrocephalus. Recent studies have also revealed a connective tissue bridge between the rectus capitis posterior minor muscle and the dura mater of the upper cervical spinal cord. A similar attachment has also been found to the spinal cord via the ligamentum nuchae. The spinal dura mater has been found to be innervated and a possible source of pain and neurological dysfunction.[8,9] These anatomical facts, as well as the biomechanical descriptions covered previously, reveal that the upper cervical spine is quite susceptible to injury and/or the entity called subluxation. The upper cervical spine has sacrificed stability for mobility as evidenced by ~50% of cervical rotation occurring between the atlanto-axial articulation. Grostic’s paper, The Dentate Ligament—Cord Distortion Hypothesis4, provides a compelling hypothesis for how these anatomical connections can lead to spinal cord distortion, in the presence of upper cervical misalignment. It is posited that the neurological dysfunction can occur via two mechanisms: 1) direct mechanical irritation of the nerves of the spinal cord, and/or 2) collapse of the small veins of the cord, producing venular congestion with a loss of nutrients necessary to carry on the high energy reactions necessary for nerve conduction. Spinal cord tension can affect the spinocerebellar tracts which can result in a functional short leg.
Afferent/efferent joint mechanoreceptive neurology also has interesting implications in this area of the spine. Mechanoreceptive innervation has been found in the cervical facet joints, ligaments, intervertebral discs.[10-13] The muscle spindle may be the most important proprioceptive receptor in the upper cervical spine. The spindles are intrafusal fibers that are imbedded within all muscles of the body; however, they are extremely dense in the suboccipital muscles.[14-20] The human experience is governed by receptors of all types. Cerebral cortical firing initiates efferent activity. However, the thalamus regulates the cerebral cortex through summation and integration. Another key point is that all sensory information goes through the thalamus (except aspects of olfaction). It is apparent how these two functions are vitally important for neurological integrity and appropriate cortical representation. Mechanoreception is the primary input into the cerebellum due to life in a gravity environment. The primary load to the thalamus is via the cerebellum due to the vast amount of afferent input required to maintain upright posture. It is plausible to theorize that stimulating or regulating mechanoreceptors can have a significant impact on the neurological activity of the brain and many bodily functions.
It appears that the cervical spine has more mechanoreceptors per surface area than any other region of the spinal column. It is thought that the upper cervical articulations have the greatest amount or receptors in the cervical spine. This may give the region the greatest potential for spinal mechanoreceptive afferentation into the neuraxis. There is also evidence suggesting that the upper cervical afferents feed directly into the vestibular and other high order nuclei.[23-32] This enables a less modified input of information from the upper cervical articulations into the brain stem nuclei, as opposed to the lower segments of the spine. Inappropriate afferentation (i.e. subluxation) and appropriate input (subluxation correction) into the vestibular nuclei is yet another plausible explanation for the functional short leg/pelvic distortion that is observed clinically with patients under upper cervical chiropractic care. This can occur by way of upper cervical mechanoreceptive functional integrity through the anterior and posterior spinal cerebellar tracts, cerebellum, vestibular nuclei, descending medial longitudinal fasciculus (medial and lateral vestibular spinal tracts), regulatory anterior horn cell pathway which affects postural motor tone.
The X-ray analysis is the real core of upper cervical procedures. Because the radiological assessment is so important, early developers, such as Dr. John Francis Grostic, felt that chiropractors should always lead the way in X-ray quality and patient safety. He was the first in the profession to advocate and teach doctors the use of aligned X-ray equipment. He collaborated with Travis Utterback to help develop self-centering head clamps, the X-ray turn-table chair and "L-Frame" apparatus. Many X-ray equipment setups (such as my own) are installed with the utilization of laser alignment to ensure precision. The issue of X-ray safety is addressed with the utilization of lead filters, high film/screen speed combinations, shielding and high kVp technique by many doctors who utilize upper cervical procedures. The use of lead filters has been shown to reduce radiation to the patient by as much as 80-90%.[33-34] Increasing film screen speed from 250 to 800 can also reduce the milliamperage per second (mas) setting by almost 70%, while not sacrificing image quality to any clinical significance.
The radiological assessment provides a quantitative analysis as opposed to only qualitative information. This makes it possible to determine if the care is actually reducing the subluxation, or if it is just moving the structures around with no net correction. Thus, quantification of the misalignment provides a means of evaluating the effectiveness of the adjustment. Orthogonally-based procedures utilize several measurements from the X-rays to calculate the correction vector used in the adjustment. The films are analyzed with manual template analysis and/or computer-aided digitization. By using this information, the goal is to compute a correction vector which will reduce all of the misalignment factors proportionately. In essence, the Procedure enables the doctor to provide a "tailor-made" correction.
It should be noted that the upper cervical X-ray analysis involves angular measurements of the atlas in the frontal (Z), sagittal (X) and transverse (Y) planes. Angular measurements in degrees are utilized, as this analysis is less prone to magnification errors in comparison to linear measurements. Inter- and intra-examiner reliability in the marking and reading of the films has been demonstrated and reveals error of only <.6o and <.5o, respectively.[36-39] Rochester and Owens have studied the issue of patient placement and the potential distortion errors that can take place in the measurement of upper cervical X-rays. Patient-to-film error can occur if head rotation is present when the film is taken. According to their study, the distortion is insignificant in most all cases seen in clinical practice. The study involved the development of a computerized algorithm, with the utilization of a three-dimensional computerized model of the cervical spine and head, as well as the measurement of X-rays from a clinical practice. Other potential errors include human measurement that can occur when the doctor draws lines on the X-rays and measures the deviations. He/she could either measure or record it incorrectly. This potential error has been greatly decreased with the development of computerized digitization programs. The previous reliability study by Rochester tested the DOC! program and revealed that it was as good as, if not superior to, manual analysis.
Post X-ray Assessment
Two large studies (n=45841 and n=20042) found that in these orthogonally-based practices, the more the subluxation was reduced, the better the patient outcome. The study by Eriksen and Owens determined this by measuring patient rating of symptoms as well as number of visits and adjustments necessary. This study concluded that post X-ray assessment was recommended to ascertain that at least 50% correction was achieved after the initial adjustment. Post X-ray assessment is also important to determine if an errant adjustment occurs; and provides information for the doctor to make the appropriate correction(s) for future adjustments. A series of case studies have been published which found that significant errors in upper cervical adjusting caused temporary iatrogenic symptomatic reactions in unsuspecting patients. This is an important finding since many believe that the upper cervical adjustment is innocuous since very little force is actually felt by the patient. This type of adjustment is too gentle to “injure” the patient, but osseous structure is realigned and the central nervous system is affected in the process. The “seasoned” doctor understands that the true tragedy is not correcting the subluxation so the patient can experience neurological integrity, as opposed to temporarily increasing the misalignment. A single reported case revealed a patient’s upper cervical subluxation being reduced significantly after a NUCCA upper cervical adjustment. The patient was then sent to a practitioner who utilized diversified/ Maitland manipulation. The patient was once again X-rayed, which revealed that the misalignments had increased more than the original subluxation. Fortunately, the patient was re-adjusted by the NUCCA doctor and the subluxation was reduced once again.
Studies have revealed that the radiographic measurement of misalignment between the occiput and atlas is not affected when the head is placed, up to a certain degree, in off-centered positions.[45-47] However, this does not indicate that X-ray placement is not important, as it can cause errors in other measurement parameters. A study by Jackson et al. involved 38 subjects who had two sets of anterior to posterior nasium and lateral cervical radiographs. The second set of X-rays was taken from one-half to four hours after the initial set. No chiropractic adjustment was administered between radiographs, although a simulated adjustment was conducted. The analyzed data revealed a reliability measurement of one-half degree for the upper angle and two-thirds of a degree for the lower angle. This study helps to further establish that the upper cervical misalignments that are measured on precision X-rays are static and that post adjustment radiography is a valid outcome assessment. One study has shown that barring trauma, an upper cervical misalignment pattern in a patient with signs of subluxation tends to be static (although the magnitude of the misalignment tends to decrease over time when the patient becomes subluxated). In other words, the upper cervical spine does not move around freely finding a new position each time the patient is radiographed. It appears that the reduction of the misalignment post adjustment is due to something other than patient placement. These reasons, taken together, explain why upper cervical protocol calls for X-ray assessment of misalignment factors in an occipito-atlanto-axial subluxation.
Upper cervical subluxations manifest clinically in various forms of postural distortion (i.e. functional leg length inequality, pelvic distortion, head and shoulder tilt, head translation, unequal weight distribution, etc.). The functional leg check is an outcome assessment utilized by most all upper cervical doctors on a visit-by-visit basis. It is my opinion that functional pelvic distortion (FPD) is a more accurate term; for what the doctor is actually measuring is muscle tone and resultant pelvic imbalance, instead of only leg length. Functional pelvic distortion contrasts with anisomelia, which is an anatomical short leg. Leg length inequality (LLI) often has a different significance to various physicians. For some, this condition is thought to have no importance until the inequality is ½” or greater. To the other extreme, many authors feel that a difference of just a few millimeters is significant for various musculoskeletal complaints.[51-59] LLI has been related to lower back pain[60-68], disc/joint degeneration[54,60,65,69-75], an increased susceptibility to sports injuries and potential improved performance[71,76-84], an association with scoliosis58,69,74,75,85-93, and its effect on bilateral weight deviation.94-99 Preliminary data have been published showing very high intra- and inter-reliability for the supine leg check assessment.100 Moderate reliability has been assessed for the prone leg check.[101-103] Pilot studies on pre- and post-assessment of FPD after an upper cervical adjustment have been conducted[104-106], with larger validity studies planned for the future.
A blinded single case study did show a statistically significant correlation between an objective measure and the FPD test for when an adjustment was indicated. Another case study involved atlanto-occipital intra-articular injection that moderated postural distortion. Another study also revealed postural changes occurring in subjects after undergoing upper cervical care. Two studies have shown statistically significant changes in right and left weight bearing pre- and post- upper cervical adjustment.[95,96] In addition, there are reports of relief of low back and leg pain[110-127], knee pain and idiopathic scoliosis[129,130] with the utilization of upper cervical specific care. This implies, but does not prove, a causal link between global postural distortion and upper cervical chiropractic care.
Other outcome assessments that have been studied in clinical and research settings with specific upper cervical chiropractic care include the following: thermocouple scanning[131-134], surface electromyography[105,106,135], somatosensory evoked potentials[136-141], static palpation[142-144] and range of motion. Palpatory and other methods of determining upper cervical misalignments and asymmetry have not been shown to be reliable.[143,144,146,147] There is also research that reveals how non-radiographic methods of determining upper cervical subluxation listings have poor concordance when compared to X-ray analysis.[146,148] The motion of the upper cervical spine is quite complicated, capable of excursion into the x, y and z planes. The X-ray procedure provides the information for the appropriate direction or vector to adjust the patient.
Studies on Patient Efficacy
Orthogonally-based upper cervical care is not a treatment for conditions or diseases, however, this subluxation-centered care has been shown to have an associative effect on various conditions. The following is a review of the peer-reviewed literature that shows a documented correlation between orthogonally-based care (Grostic/ Orthospinology, NUCCA and Atlas Orthogonality) and the improvement of various patient complaints. Studies have been published showing positive outcome for patients with cervical curve distortion[153,154], neck pain[155-156], cervicobrachialgia[157,158], motor vehicle trauma, headaches[160-161], low back pain[110-116], scoliosis, postural distortion[95,96,108], knee pain, general health enhancement[158-160], cerebral palsy, autism, Tourette’s syndrome, seizure disorders, mental dysfunction, multiple sclerosis, Arnold-Chiari malformation, HIV, cystic hygroma, asthma, bowel dysfunction[171-172] and hypertension[173-174] The previous papers involve various levels of scientific evidence which range from case studies to randomized controlled clinical trials.
This paper has provided a compelling and cogent argument for the clinical and scientific efficacy of orthogonally-based upper cervical chiropractic care. There is a logical chain of arguments that support specific upper cervical work. This chain is supported by some evidence at each link, with the evidence for some aspects being stronger than others. Given the anatomical, biomechanical and neurological complexity of the upper cervical spine, specific upper cervical work is an appropriate approach to adjust the upper cervical subluxation.
1. White AA, Panjabi MM. Clinical Biomechanics of the Spine. Philadelphia: JB Lippincott, 1978.
2. Warwick R, Williams PL, editors. Gray’s Anatomy, 35th British Edition. W.B. Saunders Co., 1973.
3. Hinson R, Zeng ZB. Epidural Attachments in the Upper Cervical Spine. Abstracts From The 15th Annual Upper Cervical Spine Conference, November 21-22, 1998, Chiropr Res J, 1999; 6(1):31-32.
4. Grostic JD. Dentate Ligament — Cord Distortion Hypothesis. Chiropr Res J, 1988; 1(1):47-55.
5. Emery JL. Kinking of the Medulla in Children with Acute Cerebral Oedema and Hydrocephalus and its Relationship to the Dentate Ligaments. J Neurol Neurosurg Psychiat, 1967; 30(3):267-275.
6. Hack GD, Koritzer RT, Robinson WL, Hallgren RC, Greenman PE. Anatomic Relation Between the Rectus Capitis Posterior Minor Muscle and the Dura Mater. Spine, 1995; 20(23):2484-2486.
7. Mitchell BS, Humphreys BK, O’Sullivan E. Attachments of the Ligamentum Nuchae to Cervical Posterior Spinal Dura and the Lateral Part of the Occipital Bone. J Manipulative Physiol Ther, 1998; 21(3): 145-148.
8. Groen GJ, Baljet Drukker J. The Innervation of the Spinal Dura Mater: Anatomy and Clinical Implications. Acta Neurochir (Wien), 1988; 92(1-4):39-46.
9. Kumar R, Berger RJ, Dunsker SB, Keller JT. Innervation of the Spinal Dura, Myth or Reality? Spine, 1996; 21(1):18-26.
10. McLain RF. Mechanoreceptor Endings in Human Cervical Facet Joints. Spine, 1994; 19(5): 495-501.
11. Jiang H, Russell G, Raso J, Moreau MJ, Hill DI, Bagnall KM. The Nature and Distribution of the Innervation of Human Supraspinal and Interspinal Ligaments. Spine, 1995; 20(8):869-876.
12. Roberts S, Eisenstein SM, Menage J, Evans EH, Ashton IK. Mechanoreceptors in Intervertebral Discs, Morphology, Distribution, and Neuropeptides. Spine, 1995; 20(24): 2645-2651.
13. Mendel T, Wink CS, Zimny ML. Neural Elements in Human Cervical Intervertebral Discs. Spine, 1992; 17(2):132-135.
14. Cooper S, Daniel PM. Muscle Spindles in Man; Their Morphology in the Lumbricals and the Deep Muscles of the Neck. Brain, 1963; 86:563-587.
15. Richmond FJ, Abrahams VC. Morphology and Distribution of Muscle Spindles in Dorsal Muscles of the Cat Neck. J Neurophysiol, 1975; 38(6):1322-1339.
16. Richmond FJR, Abrahams VC. Physiological Properties of Muscle Spindles in Dorsal Neck Muscles of the Cat. J Neurophysiol, 1979; 42(2):604-617.
17. Abrahams VC. Sensory and Motor Specialization in Some Muscles of the Neck. Trends Neuro Sci, January 1981:22-27.
18. Richmond FJR, Bakker DA. Anatomical Organization and Sensory Receptor Content of Soft Tissues Surrounding Upper Cervical Vertebrae in the Cat. J Neurophysiol, 1982; 48(1):49-61.
19. Bakker DA, Richmond FJR. Muscle Spindle Complexes in Muscles Around Upper Cervical Vertebrae in the Cat. J Neurophysiol, 1982; 48(1):62-74.
20. Kulkarni V, Chandy MJ, Babu KS. Quantitative Study of Muscle Spindles in Suboccipital Muscles of Human Foetuses. Neurol India, 2001; 49(4):355-359.
21. Guyton A. Basic Neuroscience. Saunders, 1991.
22. McLain RF, Pickar JG. Mechanoreceptor Endings in Human Thoracic and Lumbar Facet Joints. Spine, 1998; 23(2):168-173.
23. Fitz-Ritson DE. The Direct Connections of the C2 Dorsal Ganglion in the Brain Stem of the Squirrel Monkey: A Preliminary Investigation. J Can Chiropr Assoc, 1979; 23(4):131-138.
24. Brink EE, Hirai N, Wilson VJ. Influence of Neck Afferents on Vestibular Neurons. Exp Brain Res, 1980; 38:285-292.
25. Boyle R, Pompeiano O. Convergence and Interaction of Neck and Macular Vestibular Inputs on Vestibulospinal Neurons. J Neurophysiol, 1981; 45(5):852-868.
26. Reker U. Function of Proprioceptors of the Cervical Spine in the Cervico-Ocular Reflex. HNO, 1985; 33(9):426-429.
27. Edney DP, Porter JD. Neck Muscle Afferent Projections to the Brainstem of the Monkey: Implications for the Neural Control of Gaze. J Comp Neurol, 1986; 250(3):389-398.
28. Neuhuber WL, Zenker W. Central Distribution of Cervical Primary Afferents in the Rat, with Emphasis on Proprioceptive Projections to Vestibular, Perihypoglossal, and Upper Thoracic Spinal Nuclei. J Comp Neurol, 1989; 280(2):231-253.
29. Bankoul S, Neuhuber WL. A Cervical Primary Afferent Input to Vestibular Nuclei as Demonstrated by Retrograde Transport of Wheat Germ Agglutinin-Horseradis Peroxidase in the Rat. Exp Brain Res, 1990; 79:405-411.
30. Bolton PS, Tracey DJ. Neurons in the Dorsal Column Nuclei of the Rat Respond to Stimulation of Neck Mechanoreceptors and Project to the Thalamus. Brain Res, 1992; 595(1):175-179.
31. Boniver R. Whiplash Effects on the Hypothalamus and Sympathetic System. In: Cesarani. Whiplash Injuries. Diagnosis and Treatment, Springer-Verlag, 1996:59-63.
32. Neuhuber WL. Characteristics of the Innervation of the Head and Neck. Orthopade, 1998; 27(12):794-801.
33. Dickholtz M. Comments and Concerns Re X-ray Radiation (A Guide For Upper Cervical X-ray). Upper Cervical Monograph, 1989; 4(8):7-9.
34. Grostic JD. The Grostic Procedure. Today’s Chiropr, 1987; 16(3):51-52.
35. Hellstrom G, Irstam L, Nachemson A. Reduction of Radiation in Radiologic Examination of Patients with Scoliosis. Spine, 1983; 8(1):28-30.
36. Rochester RP. Inter and Intra-Examiner Reliability of the Upper Cervical X-ray Marking System: A Third and Expanded Look. Chiropr Res J, 1994; 3(1):23-31.
37. Jackson BL, Barker W, Bentz J, Gambale AG. Inter- and Intra-Examiner Reliability of the Upper Cervical X-ray Marking System: A Second Look. J Manipulative Physiol Ther, 1987; 10(4): 157-163.
38. Jackson BL, Barker WF, Gambale AG. Reliability of the Upper Cervical X-ray Marking System: A Replication Study. J Clin Invest Res, 1988; 1(1):10-13.
39. Seemann DC. A Reliability Study Using a Positive Nasium to Establish Laterality. Upper Cervical Monograph, 1994; 5(4):7-8.
40. Rochester RP, Owens EF. Patient Placement Error in Rotation and Its Affect on the Upper Cervical Measuring System. Chiropr Res J, 1996; 3(2):40-53.
41. Eriksen K, Owens EF. Upper Cervical Post X-ray Reduction and Its Relationship to Symptomatic Improvement and Spinal Stability. Chiropr Res J, 1997; 4(1):10-17.
42. Gregory RR. Mechanical and Manual Adjusting: A Comparison. Upper Cervical Monograph, 1983; 3(6):1-2.
43. Knutson GA. Case Studies of Upper Cervical Adjusting Errors: The Possibility of Chiropractic Iatrogenesis. Chiropr Res J, 1996; 3(3):20-24.
44. Kukurin GW. Chiropractic and Spinal Manipulative Therapy: A Critical Review of the Literature. Am Chiropr Assoc J Chiropr, 1985; 22(6):41-49.
45. Seemann DC, Gregory RR. A Critique of a Critique of Vectored Adjusting. Upper Cervical Monograph, 1981; 3(1):8-9.
46. Seemann DC, Dickholtz M. Range of Motion at the Atlanto-Occipital Joint: Lateral Flexion and Side Slip. Eleventh Annual Upper Cervical Spine Conference, Life College, Marietta, Georgia, 1995.
47. Hart JF. Effect of Patient Positioning on an Upper Cervical X-ray Listing: A Case Study. J Chiropr Res, 1988; 5(1):19-21.
48. Jackson BL, Barker WF, Pettibon BR, Woggon D, Bentz J, Hamilton D, Weigand M, Hester R. Reliability of the Pettibon Patient Positioning System for Radiographic Production. J Vertebral Subluxation Res, 2000; 4(1):3-11.
49. Palmer T, Denton K, Palmer J. A Clinical Investigation Into Upper-Cervical Biomechanical Stability: Part I. Upper Cervical Monograph, 1990; 4(10):2-7.
50. Woerman AL, Binder-Macleod A. Leg Length Discrepancy Assessment: Accuracy and Precision in Five Clinical Methods of Evaluation. J Orthop Sports Phys Ther, 1984; 5:230-239.
51. Nichols PJR. The Short Leg Syndrome. Br Med J, 1960; 1:1863.
52. Ingelmark BE, Lindstrom J. Asymmetries of the Lower Extremities and Pelvis and Their Relations to Lumbar Scoliosis. Acta Morpho Neerl Scand, 1963; 5: 221-234.
53. Leading Article: Short Leg Syndrome. Br Med J, 1971; 1:245.
54. Gofton JP. Studies in Osteoarthrosis of Hip and Leg Length Disparity. Can Med Assoc, 1971; 104:791-799.
55. Beal MC. The Short-Leg Problem. J Am Osteopathic Assoc, 1977; 76(10):745-751.
56. Heilig D. Principle of Lift Therapy. J Am Osteopathic Assoc, 1978; 77(6):466-472.
57. Peter J. Short Leg and Sciatica. J Am Med Assoc, 1979; 42(11): 1257-1258.
58. Travell JG, Simons DG. Myofascial Pain and Dysfunction: The Trigger Point Manual. Vol I. Baltimore, Williams Wilkins, 1983.
59. Kujala UM, Kvist M, Osterman K, Friberg O, Aalto T. Factors Predisposing Army Conscripts to Knee Extension Injuries Incurred in a Physical Training Program. Clin Orthop, 1986; 210:203-212.
60. Friberg O. Clinical Symptoms and Biomechanics of Lumbar Spine and Hip Joint in Leg Length Inequality. Spine, 1983; 8(6):643-650.
61. Sicuranza BJ, Richards J, Tisdall LH. The Short Leg Syndrome in Obstetrics and Gynecology. Am J Obstet Gynecol, 1970; 107(2):217-219.
62. Giles LGF, Taylor JR. Low-Back Pain Associated with Leg Length Inequality. Spine, 1981; 6(5):510-519.
63. Gofton P. Persistent Low Back Pain and Leg length Disparity. J Rheumatol, 1985; 12(4): 747-750.
64. Helliwell M. Leg Length Inequality and Low Back Pain. The Practitioner, 1985; 229(1403): 483-485.
65. Rothenberg RJ. Rheumatic Disease Aspects of Leg Length Inequality. Semin Arthritis Rheum, 1988; 17(3):196-205.
66. Steen H, Terjesen T, Bjerkreim I. Anisomelia. Clinical Consequences and Treatment. Tidsskr Nor Laegeforen, 1997; 117(11):1595-1600.
67. Strait BW. Case History. Chief Complaint: Pain in the Left Hip, Leg, and Low Back. AAO J, 1998; 8(2):11-12.
68. Redler I. Clinical Significance of Minor Inequalities in Leg Length. New Orleans Med Surg J, 1952; 104:308-312.
69. Friberg O. The Statics of Postural Pelvic Tilt Scoliosis: A Radiographic Study on 288 Consecutive Chronic LBP Patients. Clin Biomechanics, 1987; 2:211-219.
70. Beaudoin L, Zabjek KF, Leroux MA, Coillard C, Rivard CH. Acute Systematic and Variable Postural Adaptations Induced by an Orthopaedic Shoe Lift in Control Subjects. Eur Spine J, 1999; 8(1):40-45.
71. McCaw ST, Bates BT. Biomechanical Implications of Mild Leg Length Inequality. Br J Sp Med, 1991; 25(1):10-13.
72. Cummings G, Scholz JP, Barnes K. The Effect of Imposed Leg Length Difference on Pelvic Bone Symmetry. Spine, 1993; 18(3):368-373.
73. Hung SC, Kurokawa T, Nakamura K, Matsushita T, Shiro R, Okazaki H. Narrowing of the Joint Space of the Hip After Traumatic Shortening of the Femur. J Bone Joint Surg[Br], 1996; 78(5):718-721.
74. Giles LGF, Taylor JR. The Effect of Postural Scoliosis on Lumbar Apophyseal Joints. Scand J Rheumatology, 1984; 13(3):209-220.
75. Clarke GR. Unequal Leg Length: An Accurate Method of Detection and Some Clinical Results. Rheum Phys Med, 1972; 11(8):385-390.
76. McCaw ST. Leg Length Inequality, Implications for Running Injury Prevention. Sports Med, 1992; 14(6):422-429.
77. Bailey HW. Theoretical Significance of Postural Imbalance, Especially the “Short Leg”. J Am Ostopathic Assoc, 1978; 77(6):452-455.
78. Bolz S, Davies GJ. Leg Length Differences and Correlation with Total Leg Strength. J Orthop Sports Physical Therapy, 1984; 6(2):123-130.
79. Bone T, Hammons RR. Acute Leg Length Discrepancy Causes Increased VO2. Gait & Posture, 1996; 4:108-111.
80. Shambaugh JP, Klein A, Herbert JH. Structural Measures as Predictors of Injury in Basketball Players. Medicine and Science in Sports and Exercise, 1991; 23(5):522-527.
81. Glymph ID. Investigating the Effect of Upper Cervical Adjustment on Cycling Performance. Vector, 1999;2(4).
82. Kujala UM, Osterman K, Kvist M, Aalto T, Friberg O. Factors Predisposing to Patellar Chondropathy and Patellar Apicitis in Athletes. Int Orthop, 1986; 10(3):195-200.
83. Kujala UM, Friberg O, Aalto T, Kvist M, Osterman K. Lower Limb Asymmetry and Patellofemoral Joint Incongruence in the Etiology of Knee Exertion Injuries in Athletes. Int J Sports Med, 1987; 8(3):214-220.
84. Friberg O, Kvist M. Factors Determining the Preference of Takeoff Leg in Jumping. Int J Sports Med, 1988; 9(5):349-352.
85. Papaioannou T, Stokes I, Kenwright J. Scoliosis Associated With Limb-Length Inequality. J Bone Joint Surg[Am], 1982; 64(1):59-62.
86. Gibson PH, Papaioannou T, Kenwright J. The Influence on the Spine of Leg-Length Discrepancy After Femoral Fracture. J Bone Joint Surg[Br], 1983; 65(5):584-587.
87. Walker AP, Dickson RA. School Screening and Pelvic Tilt Scoliosis. Lancet, 1984; 2(8395): 152-153.
88. Manganiello A. Radiologic findings in idiopathic scoliosis. Etiopathogenetic interpretation. Radiol Med (Torino), 1987; 73(4):271-276.
89. Hoikka V, Ylikoski M, Tallroth K. Leg-Length Inequality has Poor Correlation with Lumbar Scoliosis, A Radiological Study of 100 Patients with Chronic Low-Back Pain. Arch Orthop Trauma Surg, 1989; 108(3):173-175.
90. Specht DL, DeBoer KF. Anatomical Leg Length Inequality, Scoliosis and Lordotic Curve in Unselected Clinic Patients. J Manipulative Physiol Ther, 1991; 14(6):368-375.
91. Potrafki B. Orthopadische Erkrankungren im Kindesalter und ihre Biologische Therapie. Biologische Medizin, 1994; 23(6):335-340.
92. Borenstein DG, Wiesel SW, Boden SD. Low Back Pain, Medical Diagnosis and Comprehensive Management, W.B. Saunders Co., 1995:216.
93. Morrissy RT, Weinstein SL, eds. Pediatric Orthopaedics, Volume II, Fourth Edition. Lippincott-Raven Publishers, 1996:635.
94. Lawrence D. Lateralization of Weight in the Presence of Structural Short Leg: A Preliminary Report. J Manipulative Physiol Ther, 1984; 7(2):105-108.
95. Seemann DC. Bilateral Weight Differential and Functional Short Leg: An Analysis of Pre and Post Data after Reduction of an Atlas Subluxation. Chiropr Res J, 1993; 2(3):33-38.
96. Seemann DC. Anatometer Measurements: A Field Study Intra- and Inter-Examiner Reliability and Pre to Post Changes Following an Atlas Adjustment. Chiropr Res J, 1999; 6(1):7-9.
97. Seemann D. A Comparison of Weight Differential Between a Group That Had a History of Spinal Problems or Had Been Under Care and a Group That Had Neither a History of Spinal Problems nor Been Under Care. Upper Cervical Monograph, 1991; 5(2):17-19.
98. Hoiriis KT, Hinson R, Elsangek O, Brown S, Verzosa GT, Burd D. Baseline Characteristics of Chiropractic Patients, Correlation of Anatometer Readings with Supine Leg-Length Inequality. J Chiropr Education, 2000; 14(1):8.
99. Mahar RK, MacLeod DA. Simulated Leg-Length Discrepancy: Its Effect on Mean Center-of-Pressure Position and Postural Sway. Arch Phys Med Rehabil, 1985; 66(12):822-824.
100.Hinson R, Brown SH. Supine Leg Length Differential Estimation: An Inter- and Intra- Examiner Reliability Study. Chiropr Res J, 1998; 5(1):17-22.
101.DeBoer KF, Harmon RO, Savoie S, Tuttle CD. Inter- and Intra-Examiner Reliability of Leg- Length Differential Measurement: A Preliminary Study. J Manipulative Physiol Ther, 1983; 6(2): 61-66.
102.Fuhr AW, Osterbauer PJ. Interexaminer Reliability of Relative Leg-Length Evaluations in the Prone, Extended Position. Chiropr Technique, 1989; 1(1):13-18.
103.Nguyen HT, Resnick DN, Caldwell SG, Elston EW, Bishop BB, Steinhouser JB, Gimmillaro TJ, Keating JC. Interexaminer Reliability of Activator Methods’ Relative Leg-Length Evaluation in the Prone Extended Position. J Manipulative Physiol Ther, 1999; 22(9):565- 569.
104.Hinson R, Pfleger B. Pre- and Postadjustment Supine Leg-Length Estimation. J Chiropr Education, 2000; 14(1):37-38.
105.Eriksen K, James KA. Pilot Study: Electromyography, Temperature Differential Device, Supine Leg Length Deficiency and Their Correlation with the Occipito-Atlanto-Axial Subluxation Complex. Eleventh Annual Upper Cervical Spine Conference, Life College, 1994.
106.Eriksen K, James KA. A Randomized Controlled Double Blind Study of Specific Upper Cervical Chiropractic Care. Twelfth Annual Upper Cervical Conference, Life College, Marietta, GA, November 18-19, 1995.
107.Knutson GA. Thermal Asymmetry of the Upper Extremity in Scalenus Anticus Syndrome, Leg-Length Inequality and Response to Chiropractic Adjustment. J Manipulative Physiol Ther, 1997; 20(7):476-481.
108.Knutson GA. Moderation of Postural Distortion Following Upper Cervical Facet Joint Block Injection: A Case Study. Chiropr Res J, 1998; 5(1):28-34.
109.Sherwood KR, Brickner DS, Jennings DJ, Mattern JC. Postural Changes After Reduction of the Atlanto-Axial Subluxation. J Chiropr Res, Summer, 1989; 5(4):96-100.
110.Hoiriis KT. Case Report: Management of Post-Surgical Chronic Low Back Pain with Upper Cervical Adjustment. Chiropr Res J, 1989; 1(3):37-42.
111.Vaillancourt PJ, Collins KF. CASE REPORT: Management of Post-Surgical Low Back Syndrome with Upper Cervical Adjustment. Chiropr Res J, 1993; 2(3):1-16.
112.Robinson SS, Collins KF, Grostic JD. A Retrospective Study: Patients with Chronic Low Back Pain Managed with Specific Upper Cervical Adjustments. Chiropr Res J, 1993; 2(4): 10-16.
113.Sweat R. Correction of Multiple Herniated Lumbar Disc by Chiropractic Intervention. J Chiropr Case Reports, 1993; 1(1):14-17.
114.Oliverio AB. Review of the Literature Adjusting Only the Cervical Spine and its Effect on Low Back Pain. Chiropr Res J, 1994; 3(1):3-6.
115.Hoiriis KT, Pfleger B, McDuffie FC, Alattar M, Owens EF. Design and Implementation of a Randomized Controlled Clinical Trial of Chiropractic Care Versus Drug Therapy for Sub-Acute Low Back Pain. Chiropr Res J, 1997; 4(2):50-63.
116.Knutson GA. Rapid Elimination of Chronic Back Pain and Suspected Long-Term Postural Distortion with Upper Cervical Vectored Manipulation: A Novel Hypothesis for Chronic Subluxation/Joint Dysfunction. Chiropr Res J, 1999; 6(2):57-64.
117.Kessinger RC, Boneva DV. A New Approach to the Upper Cervical Specific, Knee-Chest Adjusting Procedure: Part I. Chiropr Res J, 2000; 7(1):14-32.
118.Dickholtz M, Woodfield C. Atlas Correction of Patients with Neck and Back Pain Using the NUCCA Technique. (Abstracts from the 16th Annual Upper Cervical Spine Conference, November 20-21, 1999), Chiropr Res J, 1999; 6(2):86-87.
119.Sweat RW. CASE STUDY. Today’s Chiropr, 1982; 11(4):50.
120.Robinson GK. CASE STUDIES. Today’s Chiropr, 1983; 12(2):54-55.
121.Robinson GK. CASE STUDIES. Today’s Chiropr, 1983; 12(5):34-35.
122.Van Putten G. CASE STUDIES. Today’s Chiropr, 1983; 12(6):46-47.
123.Zezula LR. CASE STUDIES. Today’s Chiropr, 1984; 13(2):9-10.
124.Vogel FM. Case Studies. Today’s Chiropr, 1985; 14(1):48-49.
125.Forlizzo J. Case Studies. Today’s Chiropr, 1985; 14(3):91.
126.Van Putten G. Case Studies. Today’s Chiropr, 1985; 14(4):42-43.
127.Sweat RW, Sweat MH, Cuthbert S, Welkis R. Chiropractic Atlas Orthogonal Technique for the Care of Senior Citizens. Today’s Chiropr, 1998; 27(3):86-91.
128.Brown M, Vaillancourt P. Case Report: Upper Cervical Adjusting for Knee Pain. Chiropr Res J, 1993; 2(3):6-9.
129.Eriksen K. Correction of Juvenile Idiopathic Scoliosis After Primary Upper Cervical Care: A Case Study. Chiropr Res J, 1996; 3(3):25-33.
130.Basu KS, Blankenship NK. Chiropractic and Scoliosis: A Case Study. Chiropr Res J, 1999; 6(2):71-76.
131.James KA. Thermocouple Scanning Device Intra-Examiner and Inter-Examiner Reliability Study. 10th Annual Upper Cervical Spine Conference, Life College, 1993.
132.James KA. Correlation of Scanning Palpation and Grostic Cervical X-rays with a Thermocouple Temperature Measuring Device. (Thirteenth Annual Upper Cervical Spine Conference). Chiropr Res J, 1997; 4(1):28.
133.James KA. Inter- and Intra-Examiner Reliability in Interpretations of Readings from a Thermocouple Temperature Measuring Device. Abstracts From The 14th Annual Upper Cervical Spine Conference, November 22-23, 1997, Life University, Marietta, Georgia, Chiropr Res J, 1998; 5(1):41.
134.Berti AA. Thermocouple Heat Differential Instrument Examination and Findings in Correlation with the Supine Leg Check and X-ray Findings. Upper Cervical Monograph, 1993; 5(3):7-8.
135.Wiedemann RL. Case Studies of Surface EMG Tested at C1 & C3 Pre and Post Adjustment Along with Correlated Pre and Post X-rays. Eleventh Annual Upper Cervical Spine Conference, Life College, 1994.
136.Grostic JD. Somatosensory Evoked Potentials in Chiropractic Research. Today’s Chiropr, 1992; 21(3):56-58,90.
137.Collins KF, Pfleger B. The Neurophysiological Evaluation of the Subluxation Complex: Documenting the Neurological Component with Somatosensory Evoked Potentials. Chiropr Res J, 1994; 3(1):40-48.
138.Grostic J, Glick D, Burke E, Sheres B. Chiropractic Adjustment Reversal of Neurological Insult. Proceedings of the Int’l Conference on Spinal Manipulation, May 1992:19.
139.Glick D, Lee F, Grostic J. Documenting the Efficacy of Chiropractic Care Utilizing Somatosensory Evoked Potential (SEP) Testing: Post Spinal Adjustment Changes in SEP’s Duplicating Those Observed. Proceedings of the Int’l Conference on Spinal Manipulation, 1993:82.
140.Collins KF, Pfleger B. Significance of Functional Leg Length Inequality Upon
Somatosensory Evoked Potential Findings. Eleventh Annual Upper Cervical Spine Conference, Life College, 1994.
141.Glick DM. The Effective Utilization of Somatosensory Evoked Potentials in the Evaluation and Management of Upper Cervical Subluxations: Two Case Examples. Eleventh Annual Upper Cervical Spine Conference, Life College, 1994.
142.Sweat RW, Robinson GK, Lantz C, Weaver M. Scanning Palpation of the Cervical Spine Interexaminer Reliability Study. Digest Chiropr Economics, 1988; 30(4):14-18.
143.Spano N. Static Palpation of Muscle Imbalance as Compared to Radiographic Evaluation of C-1. J Straight Chiropr, 1995, 1(1):24-27.
144.Hart J. Comparison of X-ray Listings and Palpation Listing of the Upper Cervical Spine. J Vertebral Subluxation Res, 2000; 4(1):
145.Kessinger RC, Boneva DV. The Influence of Upper Cervical Specific Chiropractic Care on Lumbar Range of Motion. 17th Annual Upper Cervical Spine Conference, Life University, Marietta, GA, February 3-4, 2001.
146.Eriksen K. Comparison Between Upper Cervical X-ray Listings and Technique Analyses Utilizing a Computerized Database. Chiropr Res J, 1996; 3(2):13-24.
147.Jende A, Peterson CK. Validity of Static Palpation as an Indicator of Atlas Transverse Process Asymmetry. European J Chiropr, 1997; 45:35-42.
148.Steinle L, Steinle N. Examination of Relationships Between Atlas Lateral Displacement, Atlas Rotational Malposition and Supine Leg Length Disparities: A Correlation Study of 1,102 Cases. Abstracts From The 15th Annual Upper Cervical Spine Conference, November 21-22, 1998, Chiropr Res J, 1999; 6(1):25-26.
149.McAlpine JE. Subluxation Induced Cervical Myelopathy: A Pilot Study. Chiropr Res J, 1991; 2(1):7-22.
150.Reynolds C. Reduction of Hypolordosis of the Cervical Spine and Forward Head Posture with Specific Upper Cervical Adjustment and the Use of a Home Therapy Cushion. Chiropr Res J, 1998; 5(1):23-27.
151.Knutson GA. Chiropractic Correction of Atlantoaxial Rotatory Fixation. J Manipulative Physiol Ther, 1996; 19(4):268-272.
152.Eriksen K. Management of Cervical Herniated Disc with Upper Cervical Chiropractic Care: A Case Study. J Manipulative Physiol Ther, 1998; 21(1):51-56.
153.Glick DM. Conservative Chiropractic Care of Cervicobrachialgia. Chiropr Res J, 1989; 1(3): 49-52.
154.Feeley KM. Conservative Chiropractic Care of Frozen Shoulder Syndrome: A Case Study. Chiropr Res J, 1992; 2(2):31-37.
155.Knutson GA. Atlas Laterality/Laterality & Rotation and the Angular Acceleration of the Head and Neck in Motor Vehicle Accident. Chiropr Res J, 1996; 3(3):11-19.
156.Mathis P. Specific Upper Cervical Adjusting in the Supine Position. Chiropr Res J, 1993; 2(4):1-5.
157.Knutson GA, Jacob M. Possible Manifestation of Temporo-Mandibular Joint Dysfunction on Chiropractic Cervical X-ray Studies. J Manipulative Physiol Ther, 1999; 22(1): 32-37.
158.Hoiriis KT, Owens EF, Pfleger B. Changes in General Health Status During Upper Cervical Chiropractic Care: A Practice-Based Research Project.Chiropr Res J, 1997; 4(1):18-26.
159.Owens EF, Hoiriis KT, Burd D. Changes in General Health Status During Upper Cervical Chiropractic Care: PBR Progress Report. Chiropr Res J, 1998; 5(1):9-16.
160.Hoiriis KT, Burd D, Owens EF. Changes in General Health Status During Upper Cervical Chiropractic Care: A Practice-Based Research Project Update. Chiropr Res J, 1999; 6(2): 65-70.
161.Collins KF, Barker C, Brantley J, Planas V, Roopnarine C, Thornton P. The Efficacy of Upper Cervical Chiropractic Care on Children and Adults with Cerebral Palsy: A Preliminary Report. Chiro Pediatrics, 1994; 1(1):13-15.
162.Aguilar AL, Grostic JD, Pfleger B. Chiropractic Care and Behavior in Autistic Children. J Clin Chiropr Pediatr, 2000; 5(1):293-304.
163.Trotta N. The Response of an Adult Tourette Patient to Life Upper Cervical Adjustments. Chiropr Res J, 1989; 1(3):43-48.
164.Goodman RJ, Mosby JS. Cessation of a Seizure Disorder: Correction of the Atlas Subluxation Complex. J Chiropr Res Clin Invest, 1990; 6(2):43-46.
165.Thomas MD, Wood J. Upper Cervical Adjustments May Improve Mental Function. J Man Med, 1992; 6:215-216.
166.Kirby SL. A Case Study: The Effects of Chiropractic On Multiple Sclerosis. Chiropr Res J, 1994; 3(1):7-12.
167.Smith JL. Effects of Upper Cervical Subluxation Concomitant with a Mild Arnold-Chiari Malformation: A Case Study. Chiropr Res J, 1997; 4(2):77-81.
168.Selano JL, Hightower BC, Pfleger B, Collins KF, Grostic JD. The Effects of Specific Upper Cervical Adjustments on the CD4 Counts of HIV Positive Patients. Chiropr Res J, 1994; 3(1):32-39.
169.Hunt JM. Upper Cervical Chiropractic Care and the Resolution of Cystic Hygroma in a Twelve-Year-Old Female: A Case Study. J Clin Chiropr Pediatr, 2000; 5(1):315-317.
170.Hunt JM. Upper Cervical Chiropractic Care of a Pediatric Patient with Asthma: A Case Study. J Clin Chiropr Pediatr, 2000; 5(1):318-321.
171.Hunt JM. Upper Cervical Chiropractic Care of an Infant with Irregular Bowel Function: A Case Study. J Clin Chiropr Pediatr, 2000; 5(1):312-314.
172.Eriksen K. Effects of Upper Cervical Correction on Chronic Constipation. Chiropr Res J, 1994; 3(1):19-22.
173. Goodman R. Hypertension and The Atlas Subluxation Complex. J Chiropr Res Clin Investigation, 1992; 8(2):30-32.
174.Knutson, G. Significant Changes in Systolic Blood Pressure Post Vectored Upper Cervical Adjustment vs Resting Control Groups: A Possible Effect of the Cervicosympathetic and/or Pressor Reflex. J Manipulative Physiol Ther, 2001; 24:101-109.