Objectives: The purpose of this study was to assess the effect of different types of posterior stabilisation on the fusion rate of anterior lumbar interbody fusion (ALIF)

Thin section CT scanning has shown a higher rate of pseudarthrosis with ALIF than previously reported with standard radiological modalities. Cadaveric studies have demonstrated that posterior stabilisation would increase stiffness of the motion segment and is likely to enhance the rate of fusion with ALIF. The results of thin section CT scanning of ALIF, with and without posterior stabilisation, has not been reported previously.

Methods: Patients with discogenic back pain confirmed by discography underwent ALIF surgery as a stand alone procedure or with posterior stabilisation – using trans-laminar screws, unilateral pedicle screws or bilateral pedicle screws. Patients were followed up prospectively and thin section CT scanning was used to assess inter-body fusion.

Results: The fusion rate for stand alone ALIF was 51%, for patients with supplementary stabilisation with trans-laminar screws 58%, with unilateral pedicle screws 89% and with bilateral pedicle screws 88%. When ALIF was combined with pedicle screw stabilisation a significant difference in the fusion rate was found (p< 0.01).

Conclusion: The addition of pedicle screw fixation at the time of ALIF produces a significant increase in the rate of interbody fusion.

Independent reviewers performed systematic reviews of the abstracts presented at the annual meeting of the ISSLS and the CSS. Papers employing blinded or independent review of outcome were the strongest predictor of publication and papers employing this had an adjusted odds ratio of 4.7 for being published compared to those papers that did not. Other significant factors include use of an experimental design, statistically positive result, and basic science research.

To identify factors associated with eventual peer-reviewed publication in spinal research presented at national and international meetings.

This review has highlighted factors that are associated with eventual peer-reviewed publication. It will also present comparisons between the International Society for Study of the Lumbar Spine (ISSLS) and the Canadian Spine Society (CSS).

Independent reviewers performed systematic reviews of the abstracts presented at the annual meeting of the ISSLS and the CSS. All abstracts reviewed were categorized into type of research and aspects of research quality were identified. A medline database, blinded to the results of the review, was performed to identify abstracts that went onto peer-reviewed publication.

Univariate and multivariate analyses reviewed that blinding, use of an experimental design, basic science or biomechanical research, and a statistically significant positive result were significant predictors of eventual publication. Papers employing blinded or independent review of outcome were the strongest predictor of publication and papers employing this had an adjusted odds ratio of 4.7 for being published compared to those papers that did not. Other significant factors include use of an experimental design, statistically positive result, and basic science research. Overall, 23% of ISSLS’ abstracts were published within one year and 67% within two years. In contrast, 6% and 13% of CSS abstracts were published within one and two years respectively.

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 when compared to a placebo group.

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. Subjects had one or two level symptomatic disc degeneration 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 patient were blinded to the treatment. Patients followed a standard 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 6 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 (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 6 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 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.

In conclusion, this study demonstrates no significant benefit from IDET over placebo.

This study was carried out in order to document the indications, methods, complications and results of revision lumbar disc replacement surgery.

Out of a total series of 29 disc replacement operations carried out by the senior author 8 patients have required revision (10 operations). All of these patients have been followed prospectively since their initial operation and data was extracted from the case notes, theatre logs and radiographs.

The primary indications for revision were recurrence of, or failure to relieve back pain. Of the 8 patients requiring revision for their symptoms, 3 had prostheses that had clearly failed on CT. Four patients had the pros-thesis removed and were revised to a circumferential fusion using iliac crest autologous bone graft anteriorly and pedicle screws posteriorly. Three patients had a posterolateral fusion only using pedicle screw fixation with retention of the prosthesis. Two patients had a posterior procedure carried out which failed to resolve the situation satisfactorily, and subsequently had the prosthesis removed and interbody cage fusion. Out of the 6 anterior cases there were 2 injuries to the great veins requiring vascular repair. There were few complications with posterior surgery. Although numbers are small, the patients who had anterior surgery seemed to do better than those retaining their prosthesis with posterior surgery alone.

We conclude that a posterolateral fusion is a safe but symptomatically unsatisfactory revision strategy for failed disc replacement, and that anterior revision with conversion to inter-body fusion is a better option but has a higher rate of surgical morbidity.

This prospective study was carried out to document the efficacy of lumbar disc replacement using a viscoelastic prosthesis in the medium term.

Eleven patients were included in the pilot study of this prosthesis, with an average age at surgery of 41, and these have now reached 5 years follow-up. They have been followed up prospectively with clinical and radiological evaluation, and outcome assessment using the Oswestry Disability Index (ODI), Visual Analogue pain scales (VAS), and the Low Back Outcome Score (LBOS).

There have been 3 revision operations in patients who failed to get lasting symptomatic relief. Two patients have had their prosthesis removed with revision to an inter-body fusion supplemented with pedicle screw fixation, and one has been revised to a posterolateral fusion while retaining an apparently well functioning prosthesis.

In the 8 ‘survivors’ the improvement in the ODI, VAS and LBOS seen at the 2 year follow-up has been maintained in the longer term. Fine cut helical CT scan has shown that the prosthesis has undergone mechanical failure in 3 patients, without significant clinical problems. One patient (with a virtually perfect ODI and LBOS) appears to have undergone ‘autofusion’ with significant heterotopic ossification anterior to the disc prosthesis.

In conclusion, despite some successes, the rate of early failure of this prosthesis, both radiologically and clinically, is unacceptable, and its use has therefore been abandoned.

Objectives: Posterolateral annular lesions were experimentally induced and allowed to mature for 12 weeks in the intervertebral discs of sheep. IDET was performed in an attempt to denervate and repair the annular lesion. The histological and immunohistochemical effects of IDET were studied.

Summary of Background Data: IDET continues to be used as a minimally-invasive treatment for chronic discogenic low back pain, with success rates reported in up to 70% of cases. The mechanism of action by which IDET exerts its effect is poorly understood. Proposed mechanisms include the contraction of collagen and the coagulation of annular nociceptors. An ovine model was used firstly to induce a posterolateral annular lesion, secondly to assess the innervation of such a lesion, and thirdly to assess the effect of IDET on this innervation.

Methods: Posterolateral annular incisions were made in 40 lumbar discs of 20 sheep. Twelve weeks were allowed for each annular lesion to mature. IDET was then performed in the disc with the posterolateral annular tear and in another control level. IDET was performed using a modified intradiscal catheter. Temperatures were recorded in the nucleus (T_N) and the posterior annulus (T_PA). The spines were harvested at predetermined intervals up to eighteen months. Histological sections of the discs were graded for disc morphology to assess degeneration and immunohistochemical staining to assess potential denervation.

Results: Vascular granulation tissue consistent with a healing response was observed in the posterior annular tear of all incised discs from 12 weeks. PGP 9.5 positive nerve fibres were clearly identified in the adjacent periannular tissue and the outer few lamellae of the posterior annulus. During the IDET procedure the mean maximaximum T_PA was 63.6°C and the mean maximaximum T_N was 67.8°C. At sacrifice the number of nerve fibres identified in the posterior annular tear was the same for those specimens that had undergone IDET and those that had not. From six weeks after IDET there was evidence of thermal necrosis in the inner annulus and adjacent nucleus but sparing the periphery of the disc.

Conclusions: IDET delivered at 90°C in the sheep consistently heated the posterior annulus and the nucleus to a temperature normally associated with coagulation of nociceptors and collagen contraction. IDET did not denervate the posterior annular lesion. Thermal necrosis was observed within the inner annulus and adjacent nucleus from six weeks after IDET. The reported benefits from IDET appear to be related to factors other than denervation and repair.

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 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 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 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 6 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 6 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: The development of laboratory techniques in the last ten years has enabled the successful harvest, in vitro selection, culture and transplant of chondrocytes. The study proposes that transplantation of autologous chondrocytes prevents degeneration of the intervertebral disc following outer annular injury in an ovine model.

Methods: Eight sheep were anaesthetised and five contiguous lumbar discs were exposed via a left-sided posterolateral approach. Four of the animals were given full thickness annular incisions in three alternate discs. No annular incisions were made in the other 4 sheep. Costal cartilage was harvested from the left twelfth rib of all animals. Tissue was cultured and the chondrocytes were labelled in vitro with CFSE for verification following transplantation. Six weeks later autologous cultured chondrocytes were injected into the lower two alternate discs of all animals, leaving the uppermost discs and those untouched in between as internal controls. Animals were sacrificed after three, six, twelve and twenty-four weeks. Results were based on X rays, histological, and immunocytochemical assessments.

Results: Preliminary histological results up to three months showed viability of cultured chondrocytes and matrix production post transplantation. Serial X rays suggested that progressive disc degeneration was arrested in the treated discs.

Discussion: In this pilot study we have shown that cultured autologous chondrocytes can remain viable long term in vivo. These preliminary results suggest that these transplanted chondrocytes have the ability to retard and possibly prevent disc degeneration following annular incision. Previous similar studies have reported the use of chondrocytes cultured from disc, whilst this study showed that chondrocytes from a source foreign to the disc can exert positive effects. The encouraging result from this pilot study needs to be further validated to realise its potential as a treatment for degenerative disc disease.

A prospective study to evaluate the design, outcome and complications of the AcroFlex titanium/polyolefin artificial lumbar disc replacement.

11 subjects with single-level discographically proven discogenic pain of at least six months duration and refractory to conservative treatment underwent Total Disc Replacement (TDR) using the AcroFlex TDR. Surgery was performed by an anterior retroperitoneal approach. The following outcome measures were recorded pre-operatively, at 6 weeks and 3, 6, 12 and 24 months: Visual Analogue Score (VAS), Oswestry Disability Index (ODI), Low Back Outcome Score (LBOS), and SF-36. Physical examination and radiological assessment (plain radiographs, flexion/extension views, cine-radiography) were performed at the same time intervals. Complications and reoperations were recorded.

11 patients were enrolled since April 1998 (7 male / 4 female). The mean age was 41. 3 years. All patients have been followed for a minimum of two years.

Surgery averaged 136 minutes with 143 mls blood loss. There were no operative complications. The average length of stay was 6. 1 days. The mean VAS reduced from 8. 8 to 4. 4 at two years. ODI improved from 51. 3 (mean) to 20. 9 (mean) at 24 months. The mean LBOS of 18. 4 improved to 47. 3 at two years.

Patients showed improvement in all subsets of the SF-36. Radiological examination confirmed a mean flexion/extension arc of 6. 6 degrees with restoration of native disc height. Adverse events included one disc expulsion (under radiological observation), one autofusion (F/E views still confirm movement) and one catastrophic rubber failure requiring revision to combined anterior/posterior interbody fusion. As a result of this case all patients underwent ultra fine cut CT scans. An additional 4 cases showed small anterior tears in the rubber and are currently asymptomatic.

The two-year outcome of the AcroFlex TDR is reported in 11 patients. Improvements in VAS, ODI, LBOS and all domains of the SF-36 were reported by 10 of 11 patients. Radiological outcome confirmed preservation of movement and restoration of disc height. Adverse events including disc expulsion, autofusion and rubber failure demand continued vigilance.