In a recent study, O'Leary et al. [2005] reported their observations on the patterns of Charité disc prosthesis motion under physiologic loads. The purpose of this study was to investigate whether the motion patterns observed in the in vitro model are replicated in clinical practice. 55 patients with implanted SB Charité 111 artificial lumbar discs were subjected to flexion extension x-rays. Two consultant spinal surgeons and a neuro-radiological consultant were asked to classify the pattern of motion in the clinical subjects based on the patterns observed in the in vitro model. The results were recorded independently then collated. Following this first round of observations an algorithm was devised and the method of measurement was standardised. Summary of findings: There was modest correlation amongst the three observers in distinguishing motion from nonmotion (Kappa 5.6). There was less agreement on what type of motion was present. On both counts using the algorithm there was no correlation. The clinical study based on patients' flexion-extension radiographs identified the following patterns of prosthesis motion: angular motion between both the upper and lower endplates and core, with visual evidence of core motion; angular motion predominantly between the upper endplate and core, with little visual evidence of core motion; lift-off of upper prosthesis endplate from core or of core from lower endplate; core entrapment and deformation; and no motion. There are difficulties associated with the interprtation of these using only flexion extension views.Purpose of the study
Methods
Sub-optimal positioning of the implant is thought to be related to poor outcome after Lumbar Disc Replacement. Our aim was to analyse the impact of implant position in the outcome of Charite III Disc Replacement implants. 160 Charite III Lumbar Disc Replacements that were implanted between 1990 and 2000. The average age was 46 years with 62 Males and 98 Female subjects. An independent observer (HN) administered Pain score (VAS 1–10) for Low Back Pain (LBP) and Oswestry Disability Index (ODI). These clinical outcome parameters were compared with coronal and sagittal position of the implants from the latest available radiographs. Those with operation at L3L4 (small numbers = 20) and inadequate radiographs were excluded. 48 implants were optimally placed and 70 implants were placed sub optimally. Both the groups were in similar age groups (45.02 years, SD 7.61 and 48.31 years, SD 8.04). Clinical: No statistical or clinically significant difference was observed in LBP on VAS (4.92 V/S 4.41), ODI (42.8 V/S 38.0) and in Patient Satisfaction at an average follow up of 70 months. Average movement at optimally placed discs at L4L5 was 4.4o(95% CI 2.3 – 6.7) and at L5S1 was 5.9o(95% CI 4.2 – 7.5) and at sub optimally placed disc at L4L5 was 3.8o(95% CI 2.4 – 5.1) and at L5S1 was 3.8o(95% CI 2.3 – 5.3). Clinical and radiological results after Charite III Disc Replacement is NOT dependent on positioning of implants. Movements at optimally placed implants are better but is of questionable clinical relevance.
Introduction: Treatment of thoracolumbar fractures remains controversial. The treatment options are conservative management or operative treatment, either through a posterior or anterior approach. Surgery through an anterior approach provides excellent decompression through vertebrectomy and the ability to correct the deformity. Stabilisation with Moss cage and Kaneda device remains unproven. Methods and Results: This is a retrospective study of 55 consecutive patients with thoracolumbar fractures operated on between 1993–99. Indications for surgery were: neurological deficit, two or three column injury causing instability or significant kyphotic deformity . There were 34 male and 21 female patients, mean age 33 years old. Trauma was caused by a fall from a height, either due to accident (30 patients) or suicide attempt (5), RTAs (14), sporting injury (6). Other injuries included multiple level spinal fractures (9 patients), pelvic (5), calcaneal (3), talar (1) and malleolar (1) fractures. Surgery was performed on the next available list unless there was an indication for emergency intervention, (mean 5 days post injury, range 1–19). Post-operative hospital stay averaged 17 days (7–59). Forty-seven patients underwent an anterior procedure alone, whilst eight patients had combined anterior and posterior instrumentation and fusion. Mean operative time was 207 minutes (150–360) and blood loss 2670 ml (985– 7000). Nineteen patients (35% of all) had neurological deficit. Neurological status improved post-op in 85% of these patients, remained the same in nine per cent and there was a nerve root injury in one patient (revision case) which has almost recovered. Other complications included five chest infections, three UTIs, one incisional hernia, four implant problems and eight patients with thigh pain. Results were analysed according to return to work and the Oswestry Disability Score with a mean follow-up of three years. Thirty-eight patients (69%) returned to the same occupation held before the injury, 11 patients (20% ) had a lighter job and six patients ( 11% ) are not working with litigation going on. Oswestry Disability Score post-op was 24% (4%–72%). Conclusion: Compared to the natural history of conservatively treated thoracolumbar fractures, surgical treatment with anterior decompression and stabilisation with Moss cage and Kaneda device offers considerable advantages. It enables a thorough decompression and has the advantage of providing greater deformity correction than the traditional posterior approach while instrumenting fewer vertebrae, thus preserving spinal motion segments. Early mobilization of the patients is a major advantage.
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.
The results demonstrate that the failure modes of the device contain sufficient safety margins to support the use of the device in a prospective clinical study.
The growth of non-myelinated pain fibres in other settings is regulated by the cytokine Nerve Growth Factor (NGF). In this study, we have investigated the production and distribution of NGF, or more particularly its active isoform – NGF-β, and its receptors, in diseased intervertebral discs in order to establish whether this cytokine might be responsible for the observed nerve ingrowth in this situation.