A review of biomechanics of the central nervous system. Part I: Spinal canal deformations due to changes in posture. Deed Harrison,DC, Rene Cailliet,MD, Donald Harrison,PhD,DC, Stephan Troyanovich,DC, and Sanghak Harrison,DC.
Objective: To discuss how the spinal cord deforms due to 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 indexed 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 to a small increase in flexion of approximately 1mm. These small changes do not account for the clinical observation of patients having increased neurological signs and symptoms in flexion.
Key Indexing Terms: posture; spinal cord; biomechanics; stenosis.
The frequency of positive common spinal clinical examination findings in a sample of premenstrual syndrome sufferers. Maxwell Walsh,BAppSc(Chiro),GradDipMuscMgt,DipEd, and Barbara Polus,PhD, BAppSc(Chiro).
Objective: As part of a randomised clinical trial to determine the efficacy of chiropractic therapy on premenstrual syndrome (PMS), subjects were evaluated for initial underlying spinal dysfunction.
Subjects: Fifty-four subjects with diagnosed PMS.
Design: All subjects underwent a full history, physical and chiropractic examination carried out by one of two fully qualified and registered chiropractors, each with a minimum 10 years experience. The results of the assessment for the PMS group were compared to those of the non-PMS group.
Setting: RMIT teaching clinics.
Results: The PMS group had a higher percentage of positive responses for each of 12 measured spinal dysfunction indices except for range-of-motion of the low back. The indices where the increase was statistically significant (p<0.05) were cervical, thoracic and low back tenderness, low back orthopaedic testing, low back muscle weakness and the Neck Disability Index. An average of 5.4 of the 12 indices were positive for the PMS group compared to 3.0 for the non-PMS group.
Conclusions: A relatively high incidence of spinal dysfunction exists in PMS sufferers compared to a comparable group of non-PMS sufferers. This is suggestive that spinal dysfunction could be a causative factor in PMS and that chiropractic manipulative therapy may offer an alternative therapeutic approach for PMS sufferers.
Key Indexing Terms: premenstrual syndrome; spinal dysfunction; chiropractic; manipulation.
Management of acute lumbar disc herniation initially presenting as mechanical low back pain. Colin Crawford,BAppSc(Chiro), GradDipNeurosciences, and Robert Hannan,MB,BS.
Objective: To describe the clinical management, using spinal manipulation, of a male patient with risk factors for lumbar disc herniation initially suffering from what appeared to be mechanical low back pain which evolved into radiculopathy; also, to review issues pertinent to chiropractic/manipulative management of disc herniation.
Clinical Features: The patient initially suffered from unilateral low back pain and non-radicular/non-lancinating referral to the ipsilateral lower extremity.
Intervention and Outcome: Disc herniation-in-evolution was included in the differential diagnosis, which was discussed with the patient, who then gave verbal informed consent for manipulative management. A day or so after the initial manipulation the presentation evolved to include S1 radiculopathy. Computed tomography, just after onset of radiculopathy, confirmed the clinical diagnosis of lumbosacral disc herniation. The patient continued with manipulative management, and repeat CT examination after clinical resolution, about two months later, revealed reduction in size of the apparently clinically significant herniation.
Conclusion: Risk factors for the development of disc herniation should be considered when assessing patients suffering from what appears to be mechanical low back pain. The role played by manipulation in the development of disc herniation in this case was thought to be circumstantial rather than causal. Manipulation was used in the management of this patient over a period of approximately two months; after this time, clinical and partial CT imaging resolution was evident. Ongoing clinical (neurological) evaluation of patients with manifest or suspected disc herniation is an important aspect of management. Good quality trials of manipulation for patients with disc herniation are an imperative for the chiropractic profession.
Key Indexing Terms: intervertebral disc herniation; sciatica; chiropractic manipulation; lumbar vertebrae; computed tomography.
Posterior fossa ischemia and bilateral vertebral artery hypoplasia. Michael Mestan,DC.
Objective: To discuss cerebellar infarct in a patient with bilateral hypoplasia of the vertebral arteries.
Clinical Features: A 67-yr-old female suffered neck pain and headaches immediately after a minor motor vehicle accident. Fracture and dislocation were radiographically ruled out. Within a few days, the patient began to experience symptoms of vertigo and dizziness. A CT scan of the brain revealed a cerebellar infarct, and an angiogram of the vertebral arteries demonstrated bilateral hypoplasia.
Intervention and Outcome: The cerebellar infarct created mild, stable symptoms and the patient was watched closely in a hospital setting until the risk of possible complications was negligible. Following an uncomplicated and full recovery, the patient was given recommendations regarding critical neck positions to decrease the potential for further ischemic events.
Conclusion: Cerebellar infarcts are rare and may be associated with rare vascular anomalies.
Key Indexing Terms: vertebral artery; cerebellum, ischemia.
Radiographic evaluation of weightbearing orthotics and their effect on flexible pes planus. D. Robert Kuhn,DC, Nofa Shibley, DC, William Austin,DC, and Terry Yochum,DC.
Objective: To determine if any positive change in the alignment of the bones of the feet occur with the use of custom-made flexible orthotics, casted by weightbearing, in individuals having flexible pes planus.
Methods: Anteroposterior (AP) and lateral radiographs were taken with and without orthotics in place. The AP and lateral talocalcaneal angles and the lateral pitch of both the left and right foot were assessed.
Results: T-values and p-values derived from the radiographic measurements indicated statistically significant improvements in weightbearing foot alignment.
Discussion: Biomechanical faults in the pedal foundation can adversely affect any of the joints and structures of the foot/ankle complex, lower extremities, pelvis and spine.
Conclusion: This study supports the use a custom-made flexible orthotic for the improvement of pedal structural alignment.
Key Indexing Terms: orthotics; weightbearing; radiography; kinetic.
Supervision of Chiropractors: A summary of results from two surveys involving chiropractic supervisors and graduates in England and Sweden. H kan Sigrell,DC.
Background: Supervision of newly graduated health practitioner take place in many clinical settings, such as different types of hospital departments, in general practice and, now also within the chiropractic profession. The author conducted an initial study to determine the most important issues regarding the supervision of chiropractic graduates in Sweden.
Because it is important to define and discuss the format and contents for that part of the one-year post-graduate education program for the newly graduated chiropractor that takes place in private chiropractic offices, a new study was conducted involving chiropractic supervisors and new graduates in Sweden and England.
Objectives: To establish what chiropractic supervisors and new graduates believe is important for the graduates to learn during the clinical part of their postgraduate education, to describe the characteristics required (according to supervisors and graduates in the study) to be a good supervisor for a chiropractic graduate, and to investigate whether there are differences in opinions between supervisors and graduates and between the two countries.
Methods: Questionnaires were sent out to eleven Swedish chiropractic graduates, 30 English chiropractic graduates and thirty English chiropractic supervisors who had chiropractic graduates at the time of the survey.
Results: Participants agreed that the most important aspect of the clinical activities was to have regular meeting with the graduate, to be professional and to explain the patient's problems. The most important characteristic to become a good supervisor was that the supervisor is willing to spend time and listen to the graduate throughout the postgraduate training period. The Swedish participants more often considered it important to give the graduates academic articles to read.
Conclusion: The results of this study suggest that it is the human aspect and the personal relationship between the supervisor and the graduate that are important during the graduates one year postgraduate education at the chiropractic clinic. Chiropractic supervisors and new graduates both feel that one of the most important aspects of supervision is the ongoing dialogue between the supervisor and the graduate.
Key Indexing Terms: chiropractic; medical education.
An analytical model of lumbar motion segment in flexion. Maruti Gudavalli,PhD, and John Triano,DC,PhD.
Objective: To develop an analytical model of the lumbar motion segment and to determine the following under the application of flexion physiological loads: (i) the force displacement relationships of the lumbar motion segment; (ii) the forces in the ligaments, disc and facet joints; (iii) the strains in the ligaments and (iv) the effect of the transection of the ligaments.
Design: Computer modeling.
Setting: Spinal Ergonomics and Joint Research Laboratory, National College of Chiropractic.
Procedure: Computer model simulation of external loads and simulation of ligament transection.
Measures: The following parameters were predicted in flexion by means of a computer model (i) the load-displacement relationships of the lumbar motion segment; (ii) the loads in the ligaments, disc and facet joints; (iii) the strains in the ligaments and (iv) the effect of the transection of the ligaments.
Results: The load sharing among different ligaments predicted by this model under flexion load suggest that the supraspinous ligament carries the greatest load, followed by yellow ligament, capsular ligament, intertransverse ligament and interspinous ligament. The ligament strains indicate that the supraspinous ligament undergoes the maximum increase in length, followed by the interspinous ligament, yellow ligament, capsular ligament and intertransverse ligament. The transection of ligaments increased the flexibility of the joint, the strains on the rest of the ligaments, the loads on all of the rest of the ligaments and the movement on the disc, but does not have significant effect on the compressive load on the disc.
Conclusions: The analytical model predicts results similar to the experimental data on cadaver motion segments reported in the literature under flexion movement loads.
Key Indexing Terms: motion segment; computer model; loads; ligaments; strains.
