Objectives

The objective of this study is to determine an optimal antibiotic-loaded bone cement (ALBC) for infection prophylaxis in total joint arthroplasty (TJA).

Aims: To study the outcome of lumbar spinal fusions in patients with chronic lower back pain due to degenerative spinal disorders. Methods: 85 patients with DSD’s, a mean age of 46.4 years, back pain for at least 2 years (mean=7.7years) and failed conservative treatment for at least 1 year were admitted to the study. Questionnaires recorded socio-demographic characteristics; changes in pain, clinical findings, disability (Oswestry (ODI)), employment, radiographic fusion, patient satisfaction and complications. All patients had 3, 6, 12 and 24-month follow-ups. Results: There were 37 males (44.9years) and 48 females (47.6 years) with a mean BMI of 24.8; 49% were smokers. Pain improved significantly at 3months (p< 0.001); no deterioration at 2 years with 38.4% having no back pain. Motor (p< 0.01), sensory (p< 0.05) and Oswestry Disability (0.001) improved significantly at 3 months and continued throughout. Unemployment improved significantly 30.4% to 16.5% at 2 years (p< 0.04). Radiographic fusion occurred in 91.8%, instrument failure in 11.8% and 9.4% required re-operation. Patient satisfaction revealed a significant increase in excellent (p< 0.02) and poor (p< 0.03) results. Instrument failure correlated strongly with ODI (r=0.94, p< 0.04). No other significant correlations. Conclusions:With the correct patient selection, lumbar fusions for DSD’s lead to a significantly improved outcome at 2 years, with an acceptable complication rate. There is no correlation between radiographic fusion and outcome, but instrument failure leads to significantly worse outcome

Aims: To investigate the functional outcome with different autologous bone graft weights in posterolateral lumbar spine instrumentation for DSD’s. Methods: A total of 79 patients (mean age of 47.2) with chronic lower back pain for at least 2 years, with at least 1 year of failed conservative treatment and who were undergoing pos-terolateral spinal instrumentation for DSD’s were admitted to the trial. Patients were randomised into three groups to receive bone graft weights of 25g (Group A=26 patients), 50g (Group B=30 patients) and 100g (Group C=23 patients) per segment. Pain, clinical characteristics, disability (Oswestry), radiographic fusion, patient satisfaction and complications were recorded at 3, 6, 12 and 24-month follow-ups. Results: At 2 years, Group B (50g) had a significantly improved Oswestry Index, pain intensity, motor and sensory changes, and overall patient satisfaction than Group C (100g), which was significantly better than Group A (25g). There was no correlation between bone graft weight and radiographic fusion, between fusion and outcome, nor smoking and fusion or bone graft weight. Complications were similar. Conclusions: Patients had significantly better functional and clinical outcomes with bone graft weights of 50g. Bone graft weights of 25g had the worse outcomes and 100g did not seem to have any beneficial affect over 50g. We recommend autologous bone graft weights of 50g per fused spinal segments in this group of surgical patients.

Antibiotics are frequently administered prophylactically in spinal procedures to reduce the risk of disc space infection. There is still controversy, however, over which antibiotics are able to penetrate the intervertebral disc effectively and whether the charges on the antibiotics are important in determining their ability to diffuse into the negatively charged intervertebral disc.

In a prospective randomised double blind clinical study, we examined the penetration of two commonly used antibiotics, cefuroxime (negatively charged) and gentamicin (positively charged), into the intervertebral discs. Twenty patients, randomised into two separate groups, received either 1.5g cefuroxime or 5 mg/kg gentamicin prophylactically two hours before their intervertebral discs removed. A blood specimen, from which serum antibiotic levels were determined, was obtained simultaneously with each discectomy.

Clinical therapeutic levels of antibiotic were detectable in the intervertebral discs of all the ten patients who received gentamicin. Only two of the ten patients (20%) who received cefuroxime had quantifiable level of antibiotic in their discs even though serum levels of cefuroxime were at therapeutic levels in all ten patients. Our results showed that cefuroxime does not diffuse into human intervertebral discs as readily as gentamicin and suggest that the charge due to ionisable groups on the antibiotics is important in determining the penetration of antibiotics. We therefore recommend the use of gentamicin in a single prophylactic dose for all spinal procedures to reduce the incidence of post-operative discitis.