Biomedical subjects
N Bogduk
Publications and source records attributed to N Bogduk.
Use of uncalibrated biplanar radiography for the measurement of skeletal coordinates around the shoulder girdle.
Mechanical modelling of the musculoskeletal system is dependent upon information regarding the bony attachments of the relevant muscles; in order to study the biomechanics of the shoulder girdle the authors have identified the muscle attachments in three embalmed cadavers. A simple biplanar radiographic technique was then used to determine the attachment coordinates using frames of reference defined for each bone. This technique, using hand positioning without special fixtures was believed to be sufficiently accurate, bearing in mind the likely degree of biological variation. In order to test this assumption, the accuracy of the technique has been studied by measuring the agreement between the two measurements of the common coordinate in the pairs of radiographs. It was found that for the trunk, the errors in the common coordinate were always less than the natural variation; for the scapula they were of a similar magnitude but, for the humerus, the measurement errors frequently exceeded the variation in the coordinates of muscle attachments. It was concluded that, in general, uncalibrated biplanar radiography was sufficiently accurate for the determination of the spatial coordinates of muscle attachments.
The prevalence of cervical zygapophyseal joint pain. A first approximation.
A null hypothesis was tested to the effect that cervical zygapophyseal joint pain was uncommon. The prospectively recorded responses were reviewed of 318 consecutive patients with intractable neck pain who underwent provocation discography and cervical zygapophyseal joint blocks. Symptomatic zygapophyseal joints were encountered in 25% of the sample with a possibility that a further 38% suffered zygapophyseal pain but were not appropriately investigated. The null hypothesis was rejected. Cervical zygapophyseal joint pain is not rare, and is worthy of further consideration not just in research but in clinical practice.
Abnormal instantaneous axes of rotation in patients with neck pain.
Instantaneous axes of rotation for cervical motion segments C2-3 to C6-7 were determined in 109 patients with uncomplicated neck pain. Their location in each patient was compared to normal ranges determined in a previous study of 46 asymptomatic individuals. Unequivocally abnormal instantaneous axes of rotation were found in 46% of patients, and marginally abnormal instantaneous axes of rotation were found in a further 26% of patients. Abnormal instantaneous axes of rotation significantly correlated with the presence of neck pain, but the location of an abnormal axis did not correlate with the segmental source of pain as determined by provocation discography or zygapophyseal joint blocks.
A universal model of the lumbar back muscles in the upright position.
A model of the lumbar back muscles was constructed incorporating 49 fascicles of the lumbar erector spinae and multifidus. The attachment sites and sizes of fascicles were based on previous anatomic studies, and the fascicles were modeled on radiographs of nine normal volunteers in the upright position. Calculations revealed that the thoracic fibers of the lumbar erector spinae contribute 50% of the total extensor moment exerted on L4 and L5; multifidus contributes some 20%; and the remainder is exerted by the lumbar fibers of erector spinae. At upper lumbar levels, the thoracic fibers of the lumbar erector spinae contribute between 70% and 86% of the total extensor moment. In the upright posture, the lumbar back muscles exert a net posterior shear force on segments L1 to L4, but exert an anterior shear force on L5. Collectively, all the back muscles exert large compression forces on all segments. A force coefficient of 46 Ncm-2 was determined to apply for the back muscles. These results have a bearing on the appreciation of the effects on the back muscles of surgery and physiotherapy.
High-intensity zone: a diagnostic sign of painful lumbar disc on magnetic resonance imaging.
The prevalence, validity and reliability of high-intensity zones in the annulus fibrosus seen on T2-weighted magnetic resonance images of patients with intractable low-back pain were determined. This sign was readily recognized by two independent observers. It occurred in 28% of 500 patients undergoing magnetic resonance imaging for back pain. The presence of a high-intensity zone correlated significantly with the presence of Grade 4 annular disruption and with reproduction of the patient's pain. Its sensitivity as a sign of either annular disruption or pain was modest but its specificity was high, and its positive predictive value for a severely disrupted, symptomatic disc was 86%. This sign is diagnostic of painful internal disc disruption.
The anatomical basis for cervicogenic headache.
The neuroanatomical basis for cervicogenic headache is convergence in the trigeminocervical nucleus between nociceptive afferents from the field of the trigeminal nerve and the receptive fields of the first three cervical nerves. Only structures innervated by C1-C3 have been shown to be capable of causing headache. These are the muscles, joints and ligaments of the upper three cervical segments, but also include the dura mater of the spinal cord and posterior cranial fossa and the vertebral artery.
Cervical spinal cord neurons receiving sensory input from the cranial vasculature.
The superior sagittal sinus, middle meningeal artery or superficial temporal artery was stimulated electrically in anaesthetized cats. Field potential recordings were used to locate areas of maximum responses in the upper cervical cord, which were then further examined for responsive single units. Short latency units responded to stimulation of the superior sagittal sinus with a mean latency of 11.9 ms. Some units also responded at longer latencies in the 200-250 ms range. Spontaneous discharge rates of some units in a dorsolateral area of the cervical cord were accelerated by iontophoretic application of glutamic or homocysteic acid to these same units. Evoked action potentials were commonly multiphasic. Dorsolateral area units commonly received convergent input from two vessels and often had receptive fields on the face and limbs. Spontaneously active cells which respond to electrical stimulation were accelerated by the local application of bradykinin to the sinus and responses of dorsolateral area units could be reversibly blocked by local application of lignocaine to the sinus. It was concluded that the dorsolateral area is a relay area for the perception of pain from cranial vessels.
The attachments of the lumbar erector spinae.
The attachments and orientation of every fascicle of the lumbar erector spinae were determined in five cadavers and recorded radiographically. Little variation was found in the sites of muscle attachment, which enabled the construction of maps whereby these sites could be plotted on clinical radiographs or models of the lumbar spine. When all fascicles were plotted on 21 clinical radiographs using the maps previously developed, no significant difference in the orientation of fascicles was found compared with that observed in cadavers. This result vindicates the technique used to plot the location of individual fascicles of the lumbar back muscles.
The lumbar disc and low back pain.
The lumbar disc serves to sustain compression loads and is subject to tension and shear in forward bending and rotation. Its outer third is innervated and can be a source of pain. The annulus fibrosus may be injured in rotation and flexion of the lumbar spine and may become symptomatic as a ligamentous injury. Compression injuries of the disc are initially asymptomatic but may set in train a degradative process that, in time, leads to internal disc disruption, which becomes symptomatic as a result of chemical or mechanical irritation of nociceptors in the annulus fibrosus. Disc prolapse is but one possible end stage of internal disc disruption and represents the culmination of a series of destructive processes affecting the disc. This condition can be symptomatic while the external appearance of the disc remains normal and before nerve roots are affected in any way.
Cervical zygapophyseal joint pain patterns. I: A study in normal volunteers.
The pain patterns evoked by stimulation of normal cervical zygapophyseal joints were determined in five volunteers. Under fluoroscopic control, joints at segments C2-3 to C6-7 were stimulated by distending the joint capsule with injections of contrast medium. Each joint produced a clinically distinguishable, characteristic pattern of pain, which enabled the construction of pain charts that putatively could be of value in determining the segmental location of symptomatic joints in patients presenting with cervical zygapophyseal pain.
Cervical zygapophyseal joint pain patterns. II: A clinical evaluation.
To test the predictive value of segmental pain charts, ten patients with suspected cervical zygapophyseal pain were studied. Their pain distribution was recorded on a body diagram, and using pain charts derived from studies on normal volunteers, predictions were made by two observers of the segmental location of the symptomatic joint. Correct predictions were made in all nine patients who were shown to have symptomatic joints on the basis of diagnostic joint blocks. The results vindicate the accuracy of pain charts for predicting the segmental location of symptomatic joints in patients with cervical joint pain.
The accuracy of manual diagnosis for cervical zygapophysial joint pain syndromes.
The ability of a manipulative therapist to diagnose symptomatic cervical zygapophysial joint syndromes accurately was evaluated in a series of 20 patients. In 11 patients the presence, or absence, of a symptomatic joint was established by means of radiologically-controlled diagnostic nerve blocks. These patients were assessed by the manipulative therapist, without knowledge of the medical diagnosis. Another nine patients were first seen by the manipulative therapist whose diagnosis was then evaluated by means of diagnostic blocks. The manipulative therapist identified correctly all 15 patients with proven symptomatic zygapophysial joints, and specified correctly the segmental level of the symptomatic joint. None of the five patients with asymptomatic joints was misdiagnosed as having symptomatic zygapophysial joints. Thus, manual diagnosis by a trained manipulative therapist can be as accurate as can radiologically-controlled diagnostic blocks in the diagnosis of cervical zygapophysial syndromes. However, before generalized claims about the reliability of manual diagnosis can be made, further studies of this nature are required to validate intertherapist reliability and the ability of manual techniques to diagnose other spinal pain syndromes.
The innervation of the cervical intervertebral discs.
Microdissection and histologic studies were undertaken to determine the innervation of the cervical intervertebral discs. The cervical sinuvertebral nerves were found to have an upward course in the vertebral canal, supplying the disc at their level of entry and the disc above. Branches of the vertebral nerve supplied the lateral aspects of the cervical discs. Histologic studies of discs obtained at operation showed the presence of nerve fibers as deeply as the outer third of the anulus fibrosus. These anatomic findings provide the hitherto missing substrate for primary disc pain and the pain of provocation discography.
Instantaneous axes of rotation of the lumbar intervertebral joints.
Lateral radiographs of ten normal individuals were studied to determine the location of the instantaneous axis of rotation (IAR) of every lumbar vertebra for the movements of flexion and extension from the upright position and flexion from the fully extended position; and errors involved in the technique were quantified to establish confidence limits for the results of the calculations. The distribution of the IARs was found to fall within a small range from the mean location at each level, particularly for the movement of flexion from the extended position. Within-observer and between-observer errors occurred in tracing and superimposing radiographs and marking x and y coordinates. Unacceptably large errors occur when the movement of the joint is less than 5 degrees, and only the IAR for flexion from extension can be plotted with acceptable confidence. This result invalidates the notion that plotting centrodes may be of diagnostic value in recognizing mechanical disorders. The determination of a single extension to flexion IAR may be of more value clinically, to which end this study provides essential normative data.
The cervical zygapophysial joints as a source of neck pain.
Diagnostic cervical medial branch blocks and zygapophysial joint blocks were used to test the hypothesis that the cervical zygapophyseal joints can be the source of pain in patients with idiopathic neck pain. Complete temporary relief of all symptoms was obtained in 17 out of 24 consecutive patients. Two major groups of patients were those with neck pain and headache stemming from the C2-3 joints, and those with neck pain and shoulder pain stemming from the C5-6 joints. Internal-control observations in nine of the 17 patients established the diagnostic validity of the blocks used. The high yield of positive responders in this study probably reflects the propensity of patients with zygapophysial joint syndromes to gravitate to a pain clinic when this condition is not recognised in conventional clinical practice.
1987 Volvo award in basic science. The morphology of the lumbar erector spinae.
The lumbar erector spinae consists of two muscles--iliocostalis lumborum and longissimus thoracis--each with distinct thoracic and lumbar parts. The thoracic parts consist of tiny muscle bellies with segmental origins from the thorax and long caudal tendons that form the erector spinae aponeurosis. The lumbar fibers arise from the lumbar accessory processes and the L1-4 transverse processes, and insert independently of the erector spinae aponeurosis into the ilium. The intrinsic lumbar fibers of the erector spinae are poorly described in the literature, and the existence of the iliocostalis lumborum pars lumborum has rarely been recognized even though it constitutes a substantial portion of the total muscle mass acting directly on the lumbar vertebrae.