Purpose: Intra-op localisation of small nidus in Osteiod osteoma and Osteoblastomas is often difficult resulting in failed excision with persistent pain. We report two year follow-up results of the efficacy and reliability of using an intra-operative gamma probe in conjunction with fluoros-copy to aid resection in primary and revision surgeries.

Method: Eight patients (6M; 2F) with a diagnosis of osteoid osteoma (7) and osteoblastoma (1) were seen at our centre. The mean age at presentation was 20.9 years (9–31y). The tumour was localised to cervical (2), thoracic(4) and lumbar (2) posterior elements. All had back or neck pain of varying duration with a mean of 20 months (6–48mo). Three patients had failed treatments including CT-guided radiofrequency ablation in one and surgical excision under fluoroscopy in two. No case had previously utilised an intra-op gamma probe for localisation. All patients had work-up with plain X-rays, CT, MRI and 99 m Technetium bone scan to identify and localise the lesion. A pre-requisite for use of intra-op gamma probe was a positive pre-op bone scan. On the day of surgery, 600 MBq Tech HMDP (hydroxy-methylene-di-phosphate) was administered IV 3 hours prior to surgery. Fluoroscopy was used to confirm anatomical level, permanent mark made on skin and area exposed surgically. A 5 mm cadmium telluride (Cd Te) probe (which converts gamma radiation into electrical signal) and rate meter were used to scan the area containing lesion and counts per second(cps) recorded. The tumour nidus was then excised and cps from tumour bed and excised specimen recorded.

Results: The mean follow-up was 5.85 years (2–12.3y). The mean cps for osteoid osteoma pre-excision was 203.8 (60–515), which fell to 72.5 (10–220) post-excision. The cps reduced from 373 to 40.5 post-operatively for Osteoblastoma. Complete excision was recorded every time and all patients reported characteristic disappearance of pre-operative pain. All had discontinued analgesic medication and returned to normal activity by three months. All patients were followed-up regularly when they filled NDI, ODI and SF-36.

Conclusion: Gamma probe guided surgical excision facilitates accurate localisation of lesion, is less invasive and most importantly confirmation of complete excision of the tumour nidus consistently every time.

Introduction Surgeons request cross-match based on habit not evidence. The spinal unit requested 686 units of blood during 2002–2003 and transfused only 42 for elective lumbar spine surgery. This wastes money, time and blood.

Aim Optimise the transfusion requests in elective lumbar spinal surgery by creating evidence based guidelines.

Methods The data on elective operations performed on the lumbar spine during the period June 2002 to June 2003 was collected from the spinal unit database and cross-referenced with the records of blood transfusion. Cross-match: Transfusion ratios (C:T Ratio) and Transfusion Index (TI) for common procedures were calculated. Based on these results, a Maximum Surgical Blood Ordering Schedule (MSBOS) was created and prospectively audited for six months.

Conclusion Eighty units were cross-matched during the prospective audit. Therefore, in one year one hundred and sixty units would be requested. This represents a reduction of over five hundred units.

Objective: To report on the long-term follow-up (mean 14.2 years) of patients with early onset idiopathic scoliosis treated with convex epiphysiodesis (CE) and Luque trolley instrumentation (LTI) without fusion. To evaluate factors influencing curve progression during the adolescent growth spurt in such patients.

Methods: Thirty-one cases of early onset idiopathic scoliosis with documented progression were surgically treated with CE and LTI without fusion between 1984 and 1992. Twenty-three (14 male, 9 female) of 31 cases had reached a minimum of 16 years of age at follow-up. These 23 cases were reviewed. The overlapped ‘L’ configuration of Luque trolley was used for the first 14 cases (prior to 1988), the overlapped ‘U’ configuration was used subsequently in the following 9 cases.

Results: Mean age at operation was 4.3 years (range, 1.5 – 9 years). Mean pre-operative Cobb angle was 65° (range 30° – 95°), and immediate post-operative Cobb angle was 28° (range 10° – 60°). Mean follow-up was 14.2 years (range, 7–19 years). Four cases required insertion of longer Luque rods (mean age of 7.5 years).

Definitive spinal fusion was required in thirteen cases at a mean age of 14.5 years (range 12–23 years), due to progression of scoliosis in 9 cases (mean Cobb angle 55°), and the development of junctional kyphosis in 4 cases. In ten cases the correction obtained was maintained through skeletal maturity (mean Cobb angle at final follow-up 33°). These cases did not require definitive spinal fusion.

The mean growth within the instrumented segment was 3.2 cm (42% of the expected growth). Progression of scoliosis was predicted by pre-operative apical convex rib-vertebra angle (RVA) (p=0.002). Excessive growth within the instrumented segment was predictive of junctional kyphosis but not of scoliosis progression. Age at operation and initial curve magnitude were not found to be significant predictive factors. 72% of overlapped ‘L’ rod construct (10 cases), and 33% of overlapped ‘U’ rod construct (3 cases) had documented curve progression within the adolescent growth spurt and required definitive spinal fusion.

Conclusions: CE and LTI was effective in controlling early onset idiopathic scoliosis, whilst still allowing significant growth. Pre-operative convex RVA was predictive of curve progression. The overlapped ‘U’ rod construct was more effective than the overlapped ‘L’ rod construct in preventing curve progression.

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.

Motor vehicle accidents frequently cause injuries to the spine resulting in long term disability. The mechanisms of injury however, are poorly understood. Many of the currently available crash test dummies (e.g. EuroSid and Hybrid III) are deficient in consideration of the spine, lacking the correct biofidelic behaviour to accurately predict injury. We have developed a detailed mathematical model of the spine for the investigation of spinal kinematics and injury sustained during passenger vehicle impacts.

The model uses finite element analysis. Surface geometry was reconstructed using digitised co-ordinates from 6 vertebrae (T10 to L3) The location, geometry and physical properties of all 6 ligaments and the intervertebral discs were added. The model was extrapolated to represent the thoracolumbar spine. An independently developed model of the cervical spine was added. The LS-DYNA finite element analysis code was used for simulation of a wide range of non-linear dynamic scenarios. Simplifications of the model included replacement of deformable materials with rigid materials, replacement of complex joints with non-linear springs, and substitution of detailed ligament representations with springs and dampers. The complete spine model was then embedded into a dummy model (Hybrid III) to generate a realistic ‘crash loading’ on the spine.

The model has been validated against published data on stiffness, strength, range of motion, and known physical properties of individual functional spinal units. Further validation has been provided by data from volunteer and cadaveric testing. Loads representing a typical frontal impact were applied to the model. Ligamentous injury was predicted by monitoring forces and deflection within the model. The model accurately predicts bone stresses at which compressive wedge fractures, fractures of the pedicle and neural arch are known to occur.

A validated finite element model comprising 20,000 elements has been developed for analysis of spinal injury. The model accurately predicts ligamentous and bony failure. We hope the model will provide the basis for the development of casualty reducing design strategies within the automotive industry.

Objective: This study investigates whether fixation down to lumbar spine only can prevent pelvic tilt compared to pelvic fixation, in the surgical treatment of Duchenne Muscular Dystrophy (DMD).

Design: Retrospective and prospective clinical outcome study, with long-term follow up.

Materials and Methods: Nineteen cases of DMD with scoliosis had early stabilisation (mean age 11.5 years, range 9–16) with sublaminar wires and rods, and pedicle screws up to the lumbar spine. This cohort was followed up for a mean 4.2 years (3–10 years). 31 cases in another centre had late stabilisation (mean age 14.5 years, range 10–17), with Luque rod and sublaminar wire fixation, and pelvic fixation using L-rod (22 cases) configuration or Galveston technique (9 cases) and were followed up for 4.6 years (0.5–11.5 years). Post-op morbidity, Cobb angle correction and pelvic obliquity data were collected retrospectively and prospectively for comparison.

Results: In the lumbar fixation group FVC was 58%, the mean Cobb angle and pelvic obliquity were 19.8° and 9° preoperative, 3.2° and 2.2° direct postoperative, and 5.2° and 2.9° at final follow up respectively. The mean estimated blood loss was 3.3 litres and average hospital stay 7.7 days. In the pelvic fixation group FVC was 44%, the mean Cobb angle and pelvic obliquity were 48° and 19.8° preoperative, 16.7° and 7.2° direct postoperative, and 22° and 11.6° at final follow up respectively. The mean blood loss (4.1 litres) and the average hospital stay (17 days) were significantly higher (p< 0.05) compared to the lumbar fixation group. The pelvic fixation group had higher complication rate at the lower end of fixation. No progression of the pelvic obliquity was noted in the lumbar fixation group during follow up

Conclusion: Lumbar fixation may be adequate for scoliosis in DMD, if the stabilisation is performed early, before the pelvis becomes tilted, and scoliosis becomes significant. The caudal pedicular fixation in the lumbar spine stops rotation of the spine around the rods, and prevent pelvic tilt to occur. Pelvic fixation may be necessary in presence of established pelvic obliquity and larger scoliosis, but is associated with higher morbidity and complications.

Objective: To demonstrate possible advantages of combined (motor and sensory) versus single modality (either motor or sensory) intraoperative spinal cord monitoring

Design: Retrospective and prospective clinical study

Materials and Methods: One hundred and twenty-six consecutive operations in 97 patients had peroperative monitoring the lower limb motor evoked potentials (MEPs) to multi- pulse transcranial electrical stimulation (TES), and tibial nerve somatosensory evoked potentials (SEPs). Seventy-nine patients had spinal deformity surgery, and eighteen had surgery for trauma, tumor or disc herniation

Results: Combined motor and sensory monitoring was successfully achieved in 104 of 126 (82%) operations. Monitoring was limited to MEPs alone in two, and SEPs alone in eighteen cases. Neither MEPs nor SEPs were obtainable in two cases with Friedreich’s ataxia. Significant evoked potentials (EP) changes occurred in one or both modalities in 16 patients, in association with instrumentation (10) or systemic changes (6). After appropriate remedial measures, SEPs recovered either fully or partially in all cases (8/8) and MEPs in 10/15. New neurodeficits developed post-operatively in six of the sixteen patients with abnormal EPs, including two in whom SEPs had either not changed or recovered fully after remedial measures. One patient developed S3–5 sensory loss despite full recovery of both SEPs and MEPs. Two patients without neurological consequences had persistent MEP changes. Normal MEPs (but not SEPs) at the end of the operation correctly predicted the absence of new motor deficits. There were no false negative MEP changes.

Conclusion: MEPs are more sensitive than SEPs, but may rarely raise false positive alarm. SEPs are unaffected by anaesthetics and can be monitored more frequently. Combined monitoring is safe, complimentary to each other, and increases sensitivity and predictivity of adverse neorological consequences. True incidence of false positive MEP or SEP changes are difficult to define. Remedial measures after monitoring changes may help cord ischaemia to recover and absence of neurological deficit, therefore, may not indicate a false positive monitoring change.