Study Design: Prospective cohort study

Summary of Background data: A definite link between Modic end plate changes and discogenic low back pain has yet to be established. However, current prospective data indicates that Modic changes strongly correlate with the pain provocation of lumbar discography and improved clinical outcome following instrumented posterolateral fusion. Consequently, there is recent heightened awareness using this radiological entity in the selection of patients for interbody fusion or total disc replacement.

Objective: To prospectively evaluate whether Modic changes can predict improved clinical outcome following antero-posterior lumbar interbody fusion using femoral ring allograft.

Methods: A cohort of chronic low back pain patients were investigated with MRI and lumbar discography. Twenty-six patients with disco-graphically-proven concordant pain reproduction were prospectively entered into the study. Clinical results were collected using the Oswestry Disability Index (ODI), Visual Analogue Scale (VAS) and Short Form 36 Health Questionnaire (SF-36) at the pre-operative and two-year follow up. The minimal clinically important difference (MCID) was taken as 10 points for ODI, 2 points for VPAS, and 7 points for the physical function and bodily pain subset of the SF-36 questionnaire.

Results: MRI scans evaluated for the level fused revealed 13 patients with no end-plate changes (Type 0), whilst 2 patients had Modic Type I and 11 had Modic Type II changes. MCID in ODI were achieved in Type 0, Type 1 and Type 2, but improvement in VAS only was achieved in the Type 0 and Type 1. For SF-36, the MCID of 7 points was reached in most domains for all types of Modic change. There was no statistical difference in clinical outcome between those patients with Modic Type 0 and those with Modic type I or II.

Conclusion: This prospective study shows that Modic changes do not predict improved clinical outcome following antero-posterior interbody fusion using the femoral ring allograft.

Study Design: Retrospective chart review.

Objective: To assess the clinical and radiological outcome of surgery for both dystrophic and non-dystrophic curves resulting from neurofibromatosis Type I.:

Subjects: 10 patients (7 females, 3 males) underwent surgical correction for neurofibromatous kypho-scoliosis between 1997–2003. The mean age at surgery was 16 years (range 8–37 years). Average follow-up 20 months (range 9 months – 4.5 years). Seven patients had MRI proven dystrophic curves (group I). These underwent 2–3 level apical vertebrectomy, followed by 2–3 weeks in Halo traction, followed by instrumented posterior spinal fusion and anterior rib strut grafting. Three patients had non-dystrophic curves (group II). Two underwent posterior instrumented fusion and one (aged 8 years) underwent convex epiphyseodesis with posterior Luque trolley.

Outcome Measures: Cobb angle, thoracic kyphosis, lumbar lordosis, global apical vertebral translation (AVT), regional AVT, coronal and sagittal balance, complications and Modified SRS Outcomes Instrument completed at final follow.

Results: For the dystrophic curves the Cobb angle improved from a mean of 81.5 degrees (mean bending film to 76 degrees) to 26.6 degrees post-operatively (68% correction) and 35.8 degrees at final follow-up (56% correction) and the global AVT improved from 61.5 mm to 29 mm at final follow-up. The average score for the modified SRS outcome instrument was 91.6 (Good). For the non-dystrophic curves the Cobb angle improved from a mean of 57.5 degrees (mean bending film to 47 degrees) to 23.5 degrees post-operatively ( 60% correction) and 24.6 degrees at final follow-up (57% correction) and the global AVT improved from 56.8 mm to 27.8 mm at final follow-up. The average score for the modified SRS outcome instrument was 98.5 (Good). All complications occurred in the dystrophic group including superficial infection in 2, dural leaks in 3, temporary brachial plexus injury in 1, worsening of lower limb neurological deficit in 1 and one death (upper GI haemorrhage). There was no failure of metalwork or evidence of pseudarthrosis identified. Seven of eight patients stated that they would have the surgery done again.

Conclusions: Non-dystrophic curves maybe treated by posterior fusion alone achieving 60% Cobb correction and 55% AVT correction. Close observation should be maintained for the appearance of dystrophic features and deterioration of correction. Dystrophic curves should be treated early and aggressively by two/three stage apical vertebrectomy, grafting and posterior spinal fusion. In this series 68% coronal Cobb and 63% AVT correction was achieved post-operatively. Complications can be expected with scoliosis associated with more than 50 degrees of kyphosis.

Study Design: Retrospective chart review.

Summary of Background Data: Spinal osteotomy in ankylosing spondylitis is performed to restore forward gaze and sagittal balance. Closing wedge lumbar osteotomy and polysegmental thoracic osteotomy in the same patient has not been reported.

Objective: To study the factors affecting correction of sagittal balance.

Subjects: 27 patients (23 male, 4 female) operated between 1989–2002: average age 46 years: minimum follow-up: 18 months. 19 patients had lumbar osteotomy alone, 6 had both lumbar and thoracic osteotomies and 2 had thoracic osteotomy alone. Three groups were identified: A) patients with decreased lumbar-lordosis and normal thoracic-kyphosis B) Normal / increased lumbar-lordosis and increased thoracic-kyphosis C) Decreased lumbar-lordosis and increased thoracic-kyphosis.

Results: Preoperatively, mean sagittal balance was +103 mm, thoracic-kyphosis 61 degrees, and lumbar-lordosis 25 degrees. Three months postoperatively, sagittal balance was +36 mm, thoracic-kyphosis 55 degrees, and lumbar-lordosis 49 degrees. At final follow-up sagittal balance was +44 mm, thoracic-kyphosis 57 degrees and lumbar-lordosis 46 degrees. In patients who had thoracic osteotomies, thoracic-kyphosis of 78 degrees was corrected to 48 degrees. There were no spinal cord injuries or permanent nerve root palsies. Six patients had deterioration of sagittal balance (SB) (> 45 mm), 5 of them required cervical osteotomy. There was significant association between post-operative thoracic-kyphosis of > 60 degrees and SB deterioration (p-value < .001, sensitivity 100%, specificity 75%). Statistically there was no significant association between SB deterioration and post-operative sagittal balance, lumbar-lordosis, osteotomy-angle and extent of fixation.

Conclusions: Correction of thoracic-kyphosis affected final sagittal balance significantly. Consideration should be given to the simultaneous performance of lumbar osteotomy and polysegmental thoracic osteotomies in selected patients to obtain greater correction and restoration of near normal sagittal balance.

Study Design: A consecutive retrospective cohort including all patients treated by a single consultant spinal surgeon (BJCF) with targeted foraminal epidural steroid injection (FESI) for radicular pain.

Objective: To assess the efficacy of targeted foraminal epidural steroid injection (FESI) for radicular pain in preventing surgical intervention.

Summary of Background Data: 90% of sciatica resolves within 90 days. Beyond this period, decompresssive surgery for pain relief maybe considered. Open surgery however carries attendant risk including nerve root injury, dural laceration, cauda equina syndrome, deep infection, recurrent disc prolapse, epidural fibrosis and post-discectomy lumbar instability. Peri-radicular infiltration of local anaesthetic and steroid has been shown to reduce pain, at least in the short term. We were interested in whether FESI could obviate the need for surgery in refractory cases of nerve root pain.

Methods: 83 consecutive patients (45 female, 38 male) with a mean age of 51 years (range 24 to 87) presenting between November 2000 and February 2003 with radicular pain were treated with targeted FESI. 55 patients had a principal diagnosis of disc prolapse, 20 had lateral canal stenosis and 8 had degenerative spondylolisthesis. Fourteen had previous surgery and 38 had previous caudal or lumbar epidural injections.

Outcome Measures: Pain was assessed using the Visual Analogue Score and disability by the Oswestry Disability Index. The product-limit method of Kaplan Meier was used to assess the time to further procedure or the date of last review.

Results: 21 of 83 patients (25.3%) underwent an open procedure (discectomy/decompression) within the designated time period (median 20 months). Median time to open procedure was 6.5 months (mean 8.2 months). Repeat FESI was required in 16 patients (19.2%). The remaining 46 (55.4%) patients avoided any further procedure at a median of 20 months (range 13 to 36). No complications resulted from these procedures.

Conclusions: Targeted foraminal epidural steroid injection can resolve radicular pain caused by varying pathologies. Surgical procedures (decompression/discectomy) can be avoided in 74.7% of cases up to a median of 20 months thereby avoiding unnecessary surgical risk.

Study Design. A reliability study of the Modic classification.

Objective. To determine the reliability and reproducibility of the Modic classification for lumbar vertebral marrow changes.

Summary of Background data. In 1988, Modic with colleagues described two degenerative stages of vertebral marrow and endplate morphology. These were Type I (inflammatory phase) and Type II (fatty phase). Later in 1988, he added a third variety; Type III where there was marked sclerosis adjacent to the endplates. No formal reliability or reproducibility studies had been performed on the Modic classification.

Methods. This study involved five independent observers of differing spinal experience using the Modic classification to grade fifty sagittal T1 and T2 weighted MRI scans. The observers repeated the assessment at three weeks. Intra- and inter-observer reliabilities were assessed using kappa statistics.

Results. There were 7 type I, 40 type II, 1 type III and 2 normal levels. The individual intra-observer agreement was substantial or excellent with kappa values ranging from 0.71 to 1.00. The overall inter-observer agreement was excellent with a kappa value of 0.85. There was complete agreement in 78% of the levels, a difference of one type in 14% and a difference of two or more in 8% of levels. The level of experience of the observer did not correlate with a better score.

Conclusions. We have shown that the Modic classification is both reliable and reproducible. It is simple and easy to apply for observers of varying clinical experience. We therefore recommend its use in clinical research and practice.

Objective: To investigate the effects of intra-discal electro-thermal therapy (IDET) on an experimentally induced posterolateral annular inter vertebral disclesion in sheep.

Summary of Background Data: IDET is being used increasingly as a minimally-invasive treatment for chronic discogenic low back pain, with success reported in up to 70% of cases. The mechanism of action however is poorly understood. Proposed mechanisms include the contraction of collagen and the coagulation of annular nociceptors. An ovine model was used to assess the innervation of peripheral posterolateral annular lesions and the potential for IDET to denervate this region.

Methods: Posterolateral annular incisions were made in 36 lumbar discs of 18 sheep. After twelve weeks the sheep underwent IDET at one level and a sham treatment at the other level. IDET was performed using a modified intradiscal catheter (SpineCATH™, Oratec Interventions Inc., Menlo Park, CA). Temperatures were recorded in the nucleus (T_N) and the posterior annulus (T_Pa). The spines were harvested at intervals up to eighteen months. Histological sections of the discs were stained with haematoxylin and eosin and an antibody to the general neuronal marker PGP 9.5.

Results: The target temperature of 90°C at the catheter was tip was reached in all cases. The mean maximum T_Pa was 63.6°C and the mean maximum T_N 67.8°C. Vascular granulation tissue consistent with a healing response was observed in the region of the posterior annulus tear of all incised discs from 12 weeks. PGP 9.5 positive nerve fibres were clearly identified in the adjacent periannular tissue, but were scarce within the outer few lamellae of the annulus. There were no fewer nerve fibres identified in those specimens that had undergone IDET. From six weeks after IDET there was evidence of thermal necrosis in the inner annulus, sparing the periphery of the disc.

Conclusions: IDET delivered at 90°C in the sheep consistently heats the posterior annulus and the nucleus to a temperature range associated with coagulation of nociceptors and collagen contraction. Thermal necrosis was observed within the inner annulus from six weeks after IDET. In this model IDET did not produce denervation of the experimentally induced posterior annular lesion.

Study Design: Cadaveric study on the effects of Dynesys.

Summary of Background Data: Dynesys is a novel form of soft stabilization that utilises pedicle screws and modular spacers mounted on a stabilising cord to control movement of the instrumented segment in all planes. In this way it provides a biomechanical alternative with greater physiological function than spinal fusion and may prevent the penalties of “overworking” adjacent levels.

Objective: The biomechanical response of both the instrumented and adjacent intervertebral discs (IVD) is investigated under compressive loading in flexion and extension. The effects of varying spacer heights on intradiscal pressure distribution are also reported.

Methods: Twelve L3-5 cadaveric lumbar segments were compressed to 1 kN in 6° flexion, neutral and 4° extension. The stress distribution in the mid-sagittal and posterolateral diameters of both the bridged and adjacent discs was measured by withdrawing a miniature pressure transducer across the IVD. Dynesys was applied across a single level and +2mm, neutral and −2mm spacer configurations tested in each position of loading. Over 2500 stress profiles were collected and the data obtained from measurements with and without application of Dynesys was analysed.

Results: In the absence of instrumentation stress peaks in the anterior annulus increased with a greater degree of specimen flexion. In 0° to 6° flexion, Dynesys eliminated the anterior stress peaks observed in the instrumented disc in 80% of specimens tested. In the +2mm to −2mm spacer range tested, posterior stress peaks were generally seen to increase with decreasing spacer height. Little effect is seen with the application of Dynesys to a non-degenerate disc. Preliminary analysis of the data suggests that stress distribution through the adjacent disc appears largely unchanged with instrumentation of the inferior segment.

Conclusions: Dynesys has the potential to relieve peak stresses in the anterior annulus seen particularly in positions of flexion. Spacer size influences the generation of peak stresses seen within the posterior annulus. Initial observations indicate that the IVD of the adjacent motion segment is not biomechanically prejudiced following the application of Dynesys.

Study Design: Retrospective case series.

Objective: To evaluate the clinical outcome, radiographic results and complications associated with single rod anterior instrumentation in neuromuscular thoracolumbar scoliosis.

Methods: Retrospective study with mean follow up of 35 months.

Subjects: Nine patients (6F, 3M), mean age 15 years, were operated on between 1994–2000. This heterogeneous patient group consisted of five cases of spinal dysraphism, one prune belly syndrome, one arthrogryposis, one myotonic dystrophy and one congenital myopathic dystrophy (muscle-eye-brain-syndrome). All patients were ambulatory and had minimal pelvic obliquity (< 15degrees).

Outcome measures: Pre-operative, post-operative and final follow-up measurements of Cobb angles, apical vertebral translation (AVT), thoracic kyphosis, lumbar lordosis, sagittal and coronal balance were recorded along with operative complications, pseudarthrosis, metalwork failure and loss of correction.

Results: There was one rod breakage and one case of proximal thoracic curve progression requiring supplementary posterior surgery. For the remaining 7 patients, the average corrections for Cobb angle was 62% (52 to 20 degrees), AVT was 53% (5.7 to 2.7cms), and both thoracic kyphosis and lumbar lordosis remained unchanged. No pseudarthrosis, vascular or neurological complications were encountered. Subjectively results were excellent in six and good in one.

Conclusions: Selective anterior instrumentation for neuromuscular scoliosis using a single rod resulted in acceptable clinical and radiographic outcomes in this highly selected series. Advantages include preservation of distal lumbar motion segments whilst maintaining sagittal and coronal alignment. We believe that this method of scoliosis correction has a definite yet select role in patients who are ambulatory, have minimal pelvic obliquity (< 15degrees), non-progressive pathology and near normal mental function.

Study Design: Retrospective study.

Objective: To describe a modified cervico-thoracic extension osteotomy and evaluate clinical & radiographic outcomes.

Subjects: 10 patients with fixed cervico-thoracic kyphosis, average age 56 years, minimum 12 months follow-up. Three patients had psoriatic spondyloarthropathy, Three patients had previous lumbar osteotomies.

Technique: General anaesthesia and SSEP spinal cord monitoring was used. Complete laminectomy of C7, hemilaminectomy of C6 and T1, plus pedicle subtraction osteotomy and decancellisation of C7 was performed. Upon completion of the osteotomy, controlled halo manipulation allowed closure of the osteotomy: the pivot point being the anterior longitudinal ligament. Segmental fixation with lateral mass and pedicle screws plus bone graft was then added. All patients were immobilised for three months in halo-jacket.

Results: Restoration of normal forward gaze was achieved in all patients. Mean preoperative kyphosis of 17 degrees was corrected to lordosis of 36 degrees (mean total correction 53 degrees). No spinal cord injuries or permanent nerve root palsies occurred. Three patients had mild sensory radiculopathies lasting a few weeks. No loss of correction, no pseudarthrosis, one patient had 50% anterior subluxation that later united. Two deep infections were successfully treated with wound washout and antibiotics.

Conclusions: Cervico-thoracic osteotomy in ankylosing spondylitis continues to be challenging and hazardous. C7 decancellisation and extension osteotomy supplemented with segmental internal fixation provides immediate spinal stability, reduces sagittal spinal translation and associated high risk of neurological injury, whilst maintaining correction until bony union.

Introduction: Dynesys is a novel, dynamic stabilization system designed for the treatment of degenerative conditions of the lumbar spine that present with unstable motion segments. This system uses pedicle screws with a modular spacer mounted on a stabilising cord, which controls movement of the instrumented segment in all planes. The purpose of this study was to investigate changes in the biomechanic response of the intervertebral disc (IVD) under normal, flexed and extended loading conditions before and after Dynesys is applied. The IVDs of both the instrumented (bridged) and the adjacent (floating) segment were studied.

Methods: Eight L3–5 cadaveric segments were dissected and compressed to 1kN in 6° flexion, neutral and 4° extension. The test was done without spacers and with spacers measured to +2mm, neutral and −2mm, where neutral equates to the normal distance between the pedicle screws without an applied load. The stress distribution in the mid-sagittal and postero-lateral diameters of both the bridged and floating discs was measured using a miniature pressure transducer. This resulted in greater than 300 stress profiles per specimen. Disc movement and segment motion during loading were recorded using ultrasound imaging and infrared reflection respectively.

Results: Without stabilization, stress peaks observed in the anterior annulus increased by more than 85% as the specimen was loaded from 4° extension to 6°flexion. With the application of Dynesys, these anterior stress peaks were reduced across the bridged segment. This was most pronounced in 6° flexion where anterior stress peaks of greater than 1 MPa were reduced by 100% in the bridged segment in more than 90% of specimens.

Conclusions: The degree of flexion or extension of the specimen during loading influences the peak stresses generated in the annulus. Dynesys has the potential to relieve peak stresses in the anterior annulus which is most pronounced when the specimen is loaded in flexion.

Introduction: Cadaveric intervertebral discs (IVD) must perform consistently and repeatably with time and cyclic loading if the results from long experimental protocols are to be considered valid. Experiment design should take into account the potential for changes in the biomechanical properties of the intervertebral disc. Changes in the pressure distribution and stress profiles across the IVD along with variation in movement of the anterior annulus during a load cycle give a good indication as to the biomechanic status of the IVD. The purpose of this study was to assess the biomechanic response of the IVD to repeated cyclic loading, in normal, flexed and extended positions over a prolonged period.

Methods: Ten multisegment cadaveric lumbar spine specimens (L3-5 or L1-3) were dissected and compressed to 1kN in 6° flexion, neutral and 4° extension. The anterior annulus was imaged during loading using ultrasound. The stress distribution along the mid-sagittal and antero-postero-lateral (APL) diameters of both discs was measured by withdrawing a miniature pressure transducer from posterior to anterior across the IVD during loading. Stress profilometry and ultrasound imaging was performed over a two day period.

Results: Ultrasound imaging provides an easy method for observing disc movement during compressive loading of a multi-segment specimen through positions of extension and flexion. Anterior disc bulging increased by more than 150% as the specimen is loaded from 4° of extension to 6° flexion. Repeated passes of the pressure transducer across both the mid-sagittal and APL diameter of the discs produced repeatable stress profiles. Similarly, ultrasound imaging of the anterior annulus showed comparable disc movement after cyclic loading.

Conclusions: Preliminary results suggest that the biomechanical behaviour of the IVDs of a multi-segment specimen do not change significantly following prolonged testing and multiple cyclic loading.

Introduction: The purpose of this study was to evaluate the design of a titanium/polyolefin artificial disc, assess its safety and measure outcome to determine if a RCT is justified.

Methods: All subjects entered this pilot study with one or two-level disc disruption at l4/l5 and/or l5/s1 and had disabling low back pain for at least 12 months. The diagnosis was confirmed by discography. Independent assessment included physical examination, VAS for pain, Low-Back Outcome Score (LBOS), Oswestry Disability Index (ODI), SF-36, lateral flexion/extension radiographs and MRI. This was carried out preoperatively, at 6 and 12 weeks, 6 months and at 1 and 2 years. Surgery was performed by an anterior retroperitoneal approach.

Results: Twenty-eight cases (14 males; average 41 years) were operated on during 1998–2000. Surgery was performed at L5/S1 in 19, L4/L5 in 5 and both levels in 4. Operating time averaged 130 minutes with 180mls average blood loss. There were no operative complications and average length of stay was 6 days. At 2 years there was 39% average improvement in vas, 15-point average improvement in ODI, 14 point average improvement in LBOS and improvement in 5 of the 8 SF-36 sub-scales. Complications included detection by plain radiographs of early partial displacement of implant in one case and late heterotopic calcification in another. Thin section helical CT, first carried out in early 2001, revealed polyolefin tears in 10 patients, four undergoing revision surgery since 2-year follow-up. CT revealed instances of osteolysis associated with polyolefin failure and hetero-topic bone formation not seen on plain radiographs.

Discussion: Although improvements in clinical outcome comparable to that reported with fusion were obtained at two years, detection of elastomer tears by thin section CT in 36% of patients indicated the prosthesis was not suitable for clinical use. This finding was unexpected given the results of prior extensive mechanical testing¹.

Introduction Intra-Discal Electrothermal Therapy (IDET) has been proposed as a treatment for chronic discogenic low back pain. Reports from prospective outcome studies demonstrate statistically significant improvements, but to date there are no published randomized controlled trials assessing efficacy versus a placebo group.

Methods Ethical committee approval was obtained prior to the study. Patients with chronic low back pain who failed to improve with conservative therapy were considered. Inclusion criteria included the presence of one or two level symptomatic disc degeneration with posterior or postero-lateral annular tears as determined by provocative CT/discography. Patients were excluded if there was > 50% loss of disc height or previous back surgery. Fifty-seven patients were randomized with a 2:1 (IDET: Placebo) ratio, 38 to the active IDET arm and 19 to the sham procedure (placebo). In all cases the IDET catheter was positioned under sedation to cover at least 70% of the annular tear defined by the CT/discogram. An independent technician connected the catheter to the generator and either delivered electrothermal energy (active group) or did not (sham group). Both surgeon and patients were blinded to the treatment. Patients followed a standard post-procedural rehabilitation programme. Low Back Outcome Score (LBOS), Oswestry Disability Index (ODI), SF-36 questionnaire, Zung Depression Index (ZDI) and Modified Somatic Perceptions Questionnaire (MSPQ) were measured at baseline and six months. Successful outcome was defined as: no neurological deficit resulting from the procedure, improvement in LBOS of > 7 points, improvements in SF-36 subsets (pain/disability, physical functioning and bodily pain). Two subjects withdrew from the study (both IDET). Baseline demographic data, employment and workers’ compensation status, sitting tolerance, initial LBOS, ODI, SF-36, ZDI and MSPQ were similar for both groups.

Results No neurological deficits occurred as a result of either procedure. No subject in either treatment arm showed improvement of > 7 points in LBOS or specified domains of the SF-36. Mean ODI was 41.4 at baseline and 39.7 at six months for the IDET group compared to 40.7 at baseline and 41.5 at six months for the placebo group. There was no significant change in ZDI or MSPQ scores for either group. No subject in either treatment arm met criteria for successful outcome. Further analysis showed no significant change in outcome measures in either group at six months.

Conclusions This study demonstrates no significant benefit from IDET over placebo.

Objective: To identify radiographic parameters which could predict postoperative spinal decompensation in the frontal plane in King type II adolescent idiopathic scoliosis after posterior thoracic correction and fusion with third generation instrumentation systems.

Design: Retrospective radiographic analysis.

Subjects: The radiographs of 36 patients with King type II adolescent idiopathic scoliosis (AIS) who had had posterior thoracic correction and fusion, either with the Cotrel-Dubousset instrumentation (CDI) or the Universal Spine System (USS), were evaluated in terms of frontal and sagittal plane balance, curve flexibility, and curve correction with a minimum follow up of two years. Postoperative spinal decompensation in the frontal plane was investigated with respect to preoperative radiolographic parameters on standing upright AP, thoracic and lumbar supine side-bending as well as lateral standing radiographs. Spinal decompensation in the frontal plane was defined as plumbline deviation of C7 of more than 2 cm with respect to the centre sacral line within two years postoperatively. Two groups of patients were analyzed.

Outcome measures: 26 patients (72%) showed satisfactory frontal plane alignement by means of C7 plumb line deviation (group A, 1.2 cm to the left), whereas 10 patients (28%) showed spinal decompensation (group B: 2.7 cm to the left). Group differences were significant (p=0003).

Results: The two groups were found statistically equivalent in terms of preoperative C7 plumbline deviation (p=0.112, group A: 0.8 cm, group B: 0.7 cm to the left), thoracic cobb angles (p=0.093, group A: 56°, group B: 62°), lumbar cobb angles (p=0.115, group A: 42°, group B: 47°), lumbar curve flexibility (p=0.153, group A: 78%, group B: 67%); thoracic kyphosis (p=0.153) and lumbar lordosis (p=0.534) and age at operation (p=0.195), Significant group differences, however could be revealed for thoracic curve flexibility (p=0.03, group A: 43%, groupB: 25%) and the percentage of derotation of lumbar apical vertebrae in lumbar supine side-bending films in comparison to AP upright standing radiographs (p=0.002, group A: 49%, group B: 27%). Average thoracic curve correction was 51% in group A and 41% in group B. Group differences were significant (p=0.05). Average lumbar curve correction was 34% in group A and 23% in group B (p=0.09). No group differences could be revealed for postoperative thoracic kyphosis and lumbar lordosis measurements. Logistic regression analysis with C7 plumbline deviation of more than 2 cm postoperatively as the dependent variable yielded the amount of lumbar apical vertebral derotation in lumbar supine side-bending films as the only risk-factor (p=0.007).

Conclusion: Fixed lumbar rotation, measured in terms of the percentage of derotation of lumbar apical vertebrae in lumbar supine side-bending films in comparison to AP upright standing radiographs, provided the radiographic prediction of spinal decompensation in the frontal plane after posterior thoracic correction and fusion of King II type curves.

Objective: To emphasize the need to provide a controlled method of intra-operative reduction to correct fixed cervical flexion deformities in ankylosing spondylitis and to describe the technique involved.

Design: The treatment of severe fixed cervical flexion deformity in ankylosing spondylitis represents a challenging problem that is traditionally managed by a corrective cervicothoracic osteotomy. The authors describe a method of controlled surgical reduction of the deformity, which eliminates saggital translation and reduces the risk of neurological injury.

Subjects: 2 male patients aged 39 and 45 years old with ankylosing spondylitis presented with severe fixed flexion deformity of the cervical spine. Both patients had previously undergone a lumbar extension osteotomy to correct a severe thoracolumbar kyphotic deformity. As a result of the fixed cervical flexion deformity, marked restriction in forward gaze with ‘chin on chest’ deformity, feeding difficulties and personal hygiene were encountered in both. Their respective chin-brow to vertical angle was 60 and 72°. Somatosensory and motor evoked potentials were used throughout surgery. A combination of cervical lateral mass screws and thoracic pedicle screws were used. Interconnecting malleable rods were then fixed at the cervical end, thereby allowing them to slide through the thoracic clamps thus achieving a safe method of controlled closure of the cericothoracic osteotomy. When reduction was achieved, definitive pre-contoured titanium rods were interchanged. Halo-jacket was not considered necessary in view of the segmental fixation used.

Results: Good anatomical reduction was achieved, with near complete correction of the deformities, restoration of saggital balances and forward gazes. There were no neurological deficits in either patient and the postoperative recoveries were uneventful. Both osteotomies united with no deterioration noted at 2 years.

Conclusions: We illustrate a controlled method of surgical reduction during corrective cervicothoracic osteotomy of fixed cervical kyphosis in ankylosing spondylitis. This has been achieved with the use of a combination of cervical lateral mass screws and thoracic pedicle screws with interconnecting malleable rods that were later replaced with titanium rods. The authors believe that the unique technique described remains a technically demanding but adequate and safe approach for correcting such challenging deformities.

Introduction: Intradiscal electrothermal therapy (IDET) is being used increasingly as a minimally-invasive treatment for chronic discogenic low back pain, with success reported in up to 70% of cases. The mechanism of action however is poorly understood. Proposed mechanisms include the contraction of collagen and the coagulation of annular nociceptors. An ovine model was used to assess the innervation of peripheral posterolateral annular lesions and the potential for IDET to denervate this region.

Methods: Posterolateral annular incisions were made in 36 lumbar discs of 18 sheep. After twelve weeks the sheep underwent IDET at one level and a sham treatment at the other level. IDET was performed using a modified intradiscal catheter (SpineCATH™, Oratec Interventions Inc., Menlo Park, CA). Temperatures were recorded in the nucleus and the posterior annulus. The spines were harvested at intervals of up to eighteen months. Histological sections of the discs were stained with haematoxylin and eosin and an antibody to the general neuronal marker PGP 9.5.

Results: The target temperature of 90°C at the catheter tip was reached in all cases. The mean maximum T_Pa was 63.6°C and the mean maximum TN was 67.8°C. Vascular granulation tissue consistent with a healing response was observed in the region of the posterior annulus tear of all incised discs from 12 weeks. PGP 9.5 positive nerve fibres were clearly identified in the adjacent periannular tissue, but were scarce within the outer few lamellae of the annulus. There were no fewer nerve fibres identified in those specimens that had undergone IDET. From six weeks after IDET there was evidence of thermal necrosis in the inner annulus, sparing the periphery of the disc.

Discussion: IDET delivered at 90°C in the sheep consistently heats the posterior annulus and the nucleus to a temperature associated with coagulation of nociceptors and collagen contraction. Thermal necrosis was observed within the inner annulus from six weeks after IDET. In this model IDET did not appear to produce denervation of the posterior annular lesion.

INTRODUCTION: Intradiscal electrothermal therapy (IDET) is being used increasingly as a minimally-invasive treatment for chronic discogenic low back pain, with success reported in up to 70% of cases. The mechanism of action however is poorly understood. Proposed mechanisms include the contraction of collagen and the coagulation of annular nociceptors. An ovine model was used to assess the innervation of peripheral posterolateral annular lesions and the potential for IDET to denervate this region.

METHODS: Posterolateral annular incisions were made in 36 lumbar discs of 18 sheep. After twelve weeks the sheep underwent IDET at one level and a sham treatment at the other level. IDET was performed using a modified intradiscal catheter (SpineCATH^TM, Oratec Interventions Inc., Menlo Park, CA). Temperatures were recorded in the nucleus and the posterior annulus. The spines were harvested at intervals of up to eighteen months. Histological sections of the discs were stained with haematoxylin and eosin and an antibody to the general neuronal marker PGP 9.5.

RESULTS: The target temperature of 90°C at the catheter tip was reached in all cases. The mean maximum T_Pa was 63.6°C and the mean maximum T_N was 67.8°C. Vascular granulation tissue consistent with a healing response was observed in the region of the posterior annulus tear of all incised discs from 12 weeks. PGP 9.5 positive nerve fibres were clearly identified in the adjacent periannular tissue, but were scarce within the outer few lamellae of the annulus. There were no fewer nerve fibres identified in those specimens that had undergone IDET. From six weeks after IDET there was evidence of thermal necrosis in the inner annulus, sparing the periphery of the disc.

DISCUSSION: IDET delivered at 90°C in the sheep consistently heats the posterior annulus and the nucleus to a temperature associated with coagulation of nociceptors and collagen contraction. Thermal necrosis was observed within the inner annulus from six weeks after IDET. In this model IDET did not appear to produce denervation of the posterior annular lesion.

INTRODUCTION: Intra-Discal Electrothermal Therapy (IDET) has been proposed as a treatment for chronic discogenic low back pain. Reports from prospective outcome studies demonstrate statistically significant improvements, but to date there are no published randomised controlled trials assessing efficacy versus a placebo group.

METHODS: Ethical committee approval was obtained prior to the study. Patients with chronic low back pain who failed to improve with conservative therapy were considered for the study. Inclusion criteria included the presence of one or two level symptomatic disc degeneration with posterior or posterolateral annular tears as determined by provocative CT/discography. Patients were excluded if there was > 50% loss of disc height or previous back surgery. Fifty-seven patients were randomised with a 2:1 (IDET: Placebo) ratio, 38 to the active IDET arm and 19 to the sham procedure (placebo). In all cases the IDET catheter was positioned under sedation to cover at least 70% of the annular tear defined by the CT/ discogram. An independent technician connected the catheter to the generator and either delivered electrothermal energy (active group) or did not (sham group). Both surgeon and patient were blinded to the treatment. Patients followed a standard post-procedural rehabilitation programme.

OUTCOME MEASURES: Low Back Outcome Score (LBOS), Oswestry Disability Index (ODI), SF-36 questionnaire, Zung Depression Index (ZDI) and Modified Somatic Perceptions Questionnaire (MSPQ) were measured at baseline and six months. Successful outcome was defined as: No neurological deficit resulting from the procedure, improvement in LBOS of > 7 points, improvements in SF-36 subsets (pain/disability, physical functioning and bodily pain)

RESULTS: Two subjects withdrew from the study (both IDET). Baseline demographic data, employment and worker’s compensation status, sitting tolerance, initial LBOS, ODI, SF-36, ZDI and MSPQ were similar for both groups.

No neurological deficits occurred as a result of either procedure. No subject in either treatment arm showed improvement of > 7 points in LBOS or specified domains of the SF-36. Mean ODI was 41.4 at baseline and 39.7 at six months for the IDET group compared to 40.7 at baseline and 41.5 at six months for the Placebo group. There was no significant change in ZDI or MSPQ scores for either group.

DISCUSSION: No subject in either treatment arm met criteria for successful outcome. Further analysis showed no significant change in outcome measures in either group at six months. This study demonstrates no significant benefit from IDET over placebo.

Introduction: Although the ultrasound diagnosis of neural tube defects has been described extensively, anomalies of the fetal vertebral bodies have received little attention. This study aims to document the incidence of congenital hemivertebrae, the association with defects of other organ systems and discuss the outcome.

Methods: All fetuses with ultrasonographically detected vertebral anomalies presenting to the above institution over a four year period were included in the study. Those with open neural tube defects were excluded. The level and Cobb angle (where possible) were estimated from the 18 week scan. Associated congenital anomalies were noted. Radiographs were taken soon after birth and checked for accuracy of original diagnosis and patients were monitored for curve progression.

Results: Fourteen fetuses with congenital hemivertebrae were found from a total of 12,000 routine antenatal scans. Maternal age ranged from 22–32 years (mean 26.8 years) with an average term of 36.3 weeks (range 29–40). Only two fetuses were born prematurely: one at 33 weeks as part of a twin gestation (only one of the twins had an isolated hemivertebrae) and the other at 29 weeks via emergency caesarian section for fetal distress. This pregnancy was complicated by the oligohydramnios sequence (Potter syndrome). Ten of 14 fetuses had an isolated hemivertebrae. Two had VATER association (oesophageal and anal atresia) and two had multiple mosaic type congenital scoliosis, one of which had associated rib and abdominal wall malformation. All pregnancies resulted in live births. All except one child remain well at latest follow-up (average 25 months). The infant born at 29 weeks has had multiple complications of prematurity. Vertebral anomalies appeared in the thoracic spine in five, the lumbar spine in eight and the sacrum in one resulting in scoliosis in 13 and kyphosis in one. The average antenatal Cobb angle was 30°. The average postnatal Cobb angle was 32° (range 18–42). Accuracy of localisation (level and type) was good with only one error due to inability to see the S1 hemivertebrae. Six of the 14 had surgery before the age of 24 months, with the youngest aged three months. In this group the average pre-operative Cobb angle was 35° (range 25–42°). Three patients had anterior and posterior fusion in-situ without instrumentation. Three patients had hemivertebrectomy with correction and posterior instrumentation of the spine.

Conclusion: In general sonographically detected isolated fetal hemivertebrae carry a good prognosis. If associated with the oligohydramnios syndrome the fetus is at high risk. Ultrasound appears accurate in the diagnosis of both the level and type of congenital malformation. The value of early surgical management needs continued assessment.

To assess the potential for IDET to ablate nerve fibres in an experimentally induced peripheral annular lesion.

Intradiscal electrothermal therapy (IDET) is being increasingly used as a minimally-invasive treatment for discogenic low back pain, with success reported in up to 70% of cases. One proposed mechanism of IDET is ablation reported in up to 70% of cases. One proposed mechanism of IDET is ablation of nerve fibres in the peripheral annulus. An ovine model was used to assess the innervation of peripheral annular lesions and the potential for IDET to denervate this region of the disc.

Postero-lateral annular incisions were made in 32 lumbar discs of 16 sheep. At twelve weeks the sheep underwent IDET at one level and a sham treatment at the other level. IDET was performed using a modified Intradiscal Catheter (SpineCath, Oratec Interventions Inc., Menlo Park, CA). The spines were harvested at intervals up to six months. Histological sections of the discs were stained with H& E and an antibody to the general neuronal marker PGP 9.5.

Vascular granulation tissue consistent with a healing posterior annular tear was observed in all incised discs from 12 weeks, extending to an average depth of 850 μm at 0 weeks to 690 μm at 6 months. PGP 9.5 positive nerve fibres were clearly identified outside the discs but were scarce within the discs. Nerves were identified up to 300 μm inside the annulus, from the earliest time point, and there was a trend towards less innervation with time. There were no fewer nerve fibres identified in those specimens that had undergone IDET. Specimens obtained six weeks after IDET showed evidence of thermal necrosis in the inner annulus, sparing the periphery of the disc. The reported benefit from IDET appears to be related to factors other than denervation. Thermal necrosis within the annulus six weeks after IDET.