Ian Harding

Annulus fissures are mechanically and chemically conducive to the ingrowth of nerves and blood vessels.

Study Design. Mechanical and biochemical analyses of cadaveric and surgically removed discs. Objective. To test the hypothesis that fissures in the annulus of degenerated human discs are mechanically and chemically conducive to the ingrowth of nerves and blood vessels. Summary of Background Data. Discogenic back pain is closely associated with fissures in the annulus fibrosus, and with the ingrowth of nerves and blood vessels. Methods. Three complementary studies were performed. First, 15 cadaveric discs that contained a major annulus fissure were subjected to 1 kN compression, while a miniature pressure transducer was pulled through the disc to obtain distributions of matrix compressive stress perpendicular to the fissure axis. Second, Safranin O staining was used to evaluate focal loss of proteoglycans from within annulus fissures in 25 surgically removed disc samples. Third, in 21 cadaveric discs, proteoglycans (sulfated glycosaminoglycans [sGAGs]) and water concentration were measured biochemically in disrupted regions of annulus containing 1 or more fissures, and in adjacent intact regions. Results. Reductions in compressive stress within annulus fissures averaged 36% to 46%, and could have been greater at the fissure axis. Stress reductions were greater in degenerated discs, and were inversely related to nucleus pressure (R2 = 47%; P = 0.005). Safranin O stain intensity indicated that proteoglycan concentration was typically reduced by 40% at a distance of 600 &mgr;m from the fissure axis, and the width of the proteoglycan-depleted zone increased with age (P < 0.006; R2 = 0.29) and with general proteoglycan loss (P < 0.001; R2 = 0.32). Disrupted regions of annulus contained 36% to 54% less proteoglycans than adjacent intact regions from the same discs, although water content was reduced only slightly. Conclusion. Annulus fissures provide a low-pressure microenvironment that allows focal proteoglycan loss, leaving a matrix that is conducive to nerve and blood vessel ingrowth.

A comparison of traditional protractor versus Oxford Cobbometer radiographic measurement: intraobserver measurement variability for Cobb angles.

Study Design. A comparison between measurement of radiographs using a traditional protractor method and the Oxford Cobbometer, which has the potential to reduce error. Objective. To assess measurement variability of Cobb angles using the Oxford Cobbometer and to compare it to that of measurements made using the traditional protractor method. Summary of Background Data. Studies of the Cobb method have multiple sources of error and subsequent intraobserver variability. Estimates of intraobserver variability are from 2.8° to 10°. Method. Fifty-three scoliosis curves were measured by 3 examiners. Two measurement sets were performed using the traditional protractor method and two measurement sets performed using the Oxford Cobbometer. Results. For the protractor method, intraobserver variability was 9.01° (95% confidence interval 7.32–10.88). For the Cobbometer method, the value was 5.77° (95% confidence interval 3.25–7.63). The difference between error for construction and Cobbometer methods was significant (P < 0.001). Conclusions. This study demonstrates a lower intraobserver variability for the Oxford Cobbometer compared to the traditional construction method. The Oxford Cobbometer, besides being quick and easy to use, does not require the drawing of lines on films or the use of wide diameter radiographic markers and hence removes some sources of intrinsic error incurred during the traditional method of measuring Cobb angles.

Treatment of knee flexion contracture due to central nervous system disorders in adults.

BACKGROUND Studies concerning adult patients with spastic flexion contracture of the knee are rare. Such patients frequently have cutaneous and vascular complications as well as recurrence of the contracture after treatment. We present a strategy consisting of simultaneous correction of all deformities of both lower limbs, distal hamstring releases, and application of femorotibial external fixation when extension of the knee is limited by excessive posterior soft-tissue tension. METHODS A consecutive series of fifty-nine patients (ninety-seven knees) between the ages of twenty-one and seventy-seven years received surgical treatment for a flexion contracture of the knee secondary to neurological impairment. The flexion contracture was bilateral in thirty-eight patients. Preoperatively, the mean flexion contracture angle was 69 degrees and the mean passive range of motion was 61 degrees. The contracture was corrected, through medial and lateral approaches, with distal hamstring lengthening. A posterior capsulotomy was performed in thirty-five knees. Full extension of thirty-four knees was achieved intraoperatively. In seventy-seven knees, partial correction was maintained with a unilateral external fixator, and passive and active mobilization was performed four times daily after temporary removal of the spanning external fixator rod. RESULTS At the time of final follow-up, ranging from one to five years postoperatively, the mean residual flexion contracture was 6.2 degrees. Forty-five knees had complete extension, and thirty-nine knees had a residual flexion contracture of <10 degrees. No recurrence of the flexion contracture or instability was noted in any knee at the time of follow-up. There were four cutaneous complications but no vascular or neurological complications. CONCLUSIONS We believe that our surgical strategy for correction of fixed knee flexion contracture in adult patients is safe and effective. The correction improves nursing care and sitting posture, facilitating the upright position of patients who are unable to walk, and improves walking ability for patients who are able to walk.

The symptom of night pain in a back pain triage clinic.

Study Design. Prospective longitudinal study of patients attending a back pain triage clinic with night pain. Objective. To assess the importance of the symptom of night pain in patients attending a back pain triage clinic. Summary of Background Data. The 1994 US Agency for Health Care Policy and Research guidelines suggest nighttime pain should be used as a “red flag.” Night pain is known to occur in many conditions, and although common in patients with known serious pathology, the prevalence of night pain in a back pain triage clinic is not known. Methods. A total of 482 consecutive patients attending a back pain triage clinic were assessed, including history of frequency and duration of night pain. Clinical examination was performed, and demographic data obtained. Magnetic resonance imaging was performed if indicated according to local guidelines. Oswestry, visual analog scales (for pain), and hospital anxiety depression scale, patient-based outcome scores were obtained. Results. There were 213 patients who had night pain, with 90 having pain every night. No serious pathology was identified. Patients with night pain had 4.95 hours continuous sleep (range 2−7) and were woken 2.5 times/night (range 0−6). Patients with pain every night had higher Oswestry, visual analog scale, and hospital anxiety depression scale scores than those who did not. Conclusions. Although it is a significant and disruptive symptom for patients, these results challenge the specificity of the presence of night pain per se as a useful diagnostic indicator for serious spinal pathology in a back pain triage clinic.

Long-term results of Schollner costoplasty in patients with idiopathic scoliosis.

Study Design. A retrospective analysis of patients with idiopathic scoliosis treated with Schollner costoplasty. Objective. To evaluate the long-term effects of Schollner costoplasty on rib hump and respiratory function Summary Background Data. Costoplasty is an established technique to improve chest wall deformity in patients with scoliosis. Concerns have been raised of the long-term effects of costoplasty on respiratory function in adults. No long-term studies of this procedure exist. Methods. A total of 25 patients with idiopathic scoliosis rib hump deformity underwent Schollner costoplasty. There were 12 patients who underwent surgery on the convexity alone, and 13 underwent additional “concave surgery” (6 Silastic® [Dow Corning® Corp., Midland, MI] implants, 7 concave lengthenings). Five patients underwent simultaneous spinal arthrodesis. The remaining patients underwent delayed procedures (0.4 –19 years) following the index operation. Vital capacity (VC) and rib hump were measured before and after surgery, and at each attendance thereafter. Results. Mean follow-up was 10.8 years. Average reduction in rib hump was 38 mm at 6 months and 29 mm at long-term. There was no significant difference in the preoperative and long-term VC (P = 0.4), although at 6 months after surgery, there was a significant reduction in VC of 5.1%(P = 0.03). Subgroup analysis (convex only, concave lengthening, concave Silastic®) revealed a similar pattern for rib hump correction and maintenance of VC in the long-term for each group. There was no significant difference between adults and adolescents in terms of both the reduction in rib hump and the VC (P = 0.2 and 0.3) Conclusions. Rib hump correction and lung function are preserved in the long-term following Schollner costoplasty in both adults and adolescents.

The paraspinal splitting approach: a possible approach to perform multiple intercosto-lumbar neurotizations: an anatomic study.

Study Design. Descriptive anatomy. Objective. To describe the anatomy associated with the extensive transmuscular paraspinal approach required to perform multiple intercosto-lumbar neurotizations. Summary of Background Data. Neurotization of lumbar roots using lower intercostal nerves is a potential method of treating neurologic deficits after spinal cord injury. It appeared to us that the paraspinal splitting approach was potentially an optimal method to perform intercostal nerve harvesting, rerouting, and intercosto-lumbar neurotizations. Methods. Ninth, 10th, and 11th intercostal nerve harvesting and rerouting down to L2, L3, and L4 roots were performed on 50 cadavers. The descriptive anatomy and topographic landmarks are reported. Results. The mean total length of intercostal nerve harvested was 17.96 (range, 10–27) cm for the 9th intercostal nerve, 17.14 cm (range, 10–20) for the 10th intercostal nerve and 15.94 cm (range, 10–25) for the 11th intercostal nerve. The length of harvested nerve was not correlated to the size of the trunk. The length of harvested nerve was sufficient to perform lumbar roots neurotizations in the 300 cases of nerve harvesting. Conclusion. Multiple lumbar roots neurotizations with lower intercostal nerves already have been proposed by other authors. In this strategy, the use of the spinal cord and intercostal nerves above the spinal cord lesion avoids the axonal regrowth required via the injured central nervous system. Rerouting intercostals nerves down to the lumbar roots at their exit from the intervertebral foraminae is less invasive that the same procedure performed down to the vertebral canal at the level of the cauda equina as we used in previous protocols. Our anatomic study confirms the advantage of the paraspinal sacrospinalis splitting approach in multiple intercosto-lumbar neurotizations. The approach is quick and easy and allows a good exposure of the nerve roots at the thoracic and lumbar levels. The L2, L3, and L4 roots could be satisfactorily neurotized with this procedure.

Surgical treatment of severe thoracic scoliosis in skeletally mature patients.

The few number of severe thoracic scoliosis requiring surgical treatment makes the description of its therapeutic course difficult. Twenty-one cases of severe thoracic scoliosis with Cobbs angle >90 degrees were treated surgically in the past 20 years. Surgical treatment was performed because of an evolutive scoliosis or in case of respiratory or functional impairment. All patients underwent posterior approach after a preoperative preparation by the use of halo-traction. In 6 cases, a previous surgical posterior spinal release was performed before the halo-traction period. Fusion achieved in all cases and the final correction was generally better than preoperative reducibility. The surgical course was guided by the poor functional status of these patients, especially concerning respiratory function. Spinal instrumentation was made up of 3 rods with few spinal implants in the majority of the cases. Surgical correction was made by means of rods narrowing without any rods rotation procedures. Functional improvement, especially respiratory was noted in all the cases. Nevertheless, postoperative spirometries were not significantly different from the preoperative ones. The aesthetic improvement of the rib hump was disappointing making necessary a complementary thoracoplasty in two cases. Surgical treatment of severe thoracic scoliosis remains justified in adults because of a progressive functional and radiological deterioration with respiratory compromise. We performed spinal fusion by posterior approach only, after a preoperative period of halo-traction. The final correction depends on the preoperative reducibility. We noted a functional and respiratory improvement in all the cases.

Nerves and blood vessels in degenerated intervertebral discs are confined to physically disrupted tissue

Nerves and blood vessels are found in the peripheral annulus and endplates of healthy adult intervertebral discs. Degenerative changes can allow these vessels to grow inwards and become associated with discogenic pain, but it is not yet clear how far, and why, they grow in. Previously we have shown that physical disruption of the disc matrix, which is a defining feature of disc degeneration, creates free surfaces which lose proteoglycans and water, and so become physically and chemically conducive to cell migration. We now hypothesise that blood vessels and nerves in degenerated discs are confined to such disrupted tissue. Whole lumbar discs were obtained from 40 patients (aged 37–75 years) undergoing surgery for disc herniation, disc degeneration with spondylolisthesis or adolescent scoliosis (‘non‐degenerated’ controls). Thin (5‐μm) sections were stained with H&E and toluidine blue for semi‐quantitative assessment of blood vessels, fissures and proteoglycan loss. Ten thick (30‐μm) frozen sections from each disc were immunostained for CD31 (an endothelial cell marker), PGP 9.5 and Substance P (general and nociceptive nerve markers, respectively) and examined by confocal microscopy. Volocity image analysis software was used to calculate the cross‐sectional area of each labelled structure, and its distance from the nearest free surface (disc periphery or internal fissure). Results showed that nerves and blood vessels were confined to proteoglycan‐depleted regions of disrupted annulus. The maximum distance of any blood vessel or nerve from the nearest free surface was 888 and 247 μm, respectively. Blood vessels were greater in number, grew deeper, and occupied more area than nerves. The density of labelled blood vessels and nerves increased significantly with Pfirrmann grade of disc degeneration and with local proteoglycan loss. Analysing multiple thick sections with fluorescent markers on a confocal microscope allows reliable detection of thin filamentous structures, even within a dense matrix. We conclude that, in degenerated and herniated discs, blood vessels and nerves are confined to proteoglycan‐depleted regions of disrupted tissue, especially within annulus fissures.

The Relationship between Sacral Kyphosis and Pelvic Incidence

Study Design Retrospective cohort study. Purpose Evaluate the fixed anatomical parameter of sacral kyphosis (SK) and its relationship with pelvic incidence (PI). Overview of Literature Pelvic parameters determine pelvic and lumbar spinal position. Studies have defined normative values, and have evaluated the role of these parameters in clinical practice. It has been suggested that a ratio of sacral slope (SS)/PI <0.5 predisposes to spinal pathology. PI=SS+pelvic tilt (PT) and therefore for a given PI, patients with a higher SS due to an elevated SK will potentially predispose to an unfavourable SS/PI ratio. Methods CT measurements of SS and PI were made in 100 consecutive patients from our database. Imagings without clear landmarks were excluded. PI and SK were measured using standardised techniques. Pearsons correlation was used to assess association between PI and SK, in addition to the correlation between age and the pelvic parameters. Gender specific values for PI and SK were compared using an unpaired Student t-test. Results Ninety-five patients (52 females) with a mean age 51.3 years were available for analysis. A strong positive correlation between the PI and the SK was identified (Pearsons coefficient=0.636, R2 value=0.404). Neither PI nor SK had a statistically significant correlation with age (p=0.721 and p=0.572, respectively). The mean values of both the PI and SK were statistically significantly lower in females when compared to males (p=0.0461 and p=0.0031, respectively). Conclusions A strong correlation between PI and SK exists and is a reflection of different pelvic morphologies. SK partially determines SS and a relatively high SK compared to PI will result in less ability to change PT and a potentially unfavourable SS/PI ratio, which could theoretically contribute to clinical pathology.

Myelography in the Assessment of Degenerative Lumbar Scoliosis and Its Influence on Surgical Management

Objective Myelography has been shown to highlight foraminal and lateral recess stenosis more readily than computed tomography (CT) or magnetic resonance imaging (MRI). It also has the advantage of providing dynamic assessment of stenosis in the loaded spine. The advent of weight-bearing MRI may go some way towards improving assessment of the loaded spine and is less invasive, however availability remains limited. This study evaluates the potential role of myelography and its impact upon surgical decision making. Methods Of 270 patients undergoing myelography during 2006–2009, a period representing peak utilisation of this imaging modality in our unit, we identified 21 patients with degenerative scoliosis who fulfilled our inclusion criteria. An operative plan was formulated by our senior author based initially on interpretation of an MRI scan. Subsequent myelogram and CT myelogram investigations were scrutinised, with any additional abnormalities noted and whether these impacted upon the operative plan. Results From our 21 patients, 18 (85.7%) had myelographic findings not identified on MRI. Of note, in 4 patients, supine CT myelography yielded additional information when compared to supine MRI in the same patients. The management of 7 patients (33%) changed as a result of myelographic investigation. There were no complications of myelography of the total 270 analysed. Conclusion MRI scan alone understates the degree of central and lateral recess stenosis. In addition to the additional stenosis displayed by dynamic myelography in the loaded spine, we have also shown that static myelography and CT myelography are also invaluable tools with regards to surgical planning in these patients.