Study Design: In a prospective study, intervertebral disc material from 64 patients undergoing discectomy for sciatica and 23 control patients was analysed for the presence of bacteria.

Objective: There have been many theories postulated as to the pathogenesis of back pain and sciatica. Possible inflammatory or auto-immune aetiologies have been suggested. Stirling et al (2001) suggested a possible link between sciatica and bacterial infection by demonstrating the presence of bacteria in disc material from 19 of 36 patients with severe sciatica. Previously, we developed methods for improved detection of bacterial infection associated with failed hip implants (Tunney et al 1999).These techniques have now been applied to the detection of bacteria in intervertebral discs from patients with sciatica.

Outcome Measures: Bacterial culture and non-culture immunofluorescence microscopy, using specific monoclonal antibodies, were applied to intervertebral disc material for the detection of bacterial infection. The results were also compared with functional scores before and after surgery.

Results: This study found that 20% (n=13) of patients suffering from sciatica had culture-positive disc material compared to 9% (n=2) of controls. The anaerobe Propionibacterium acnes was the predominant bacterium isolated in both case and control groups. Bacteria were also identified in skin, wound tissue and wound washings in some patients.

Conclusions: We are unable to demonstrate an association between sciatica and infection (p=0.335). This study suggests that bacteria detected in retrieved disc material may result from skin contamination during surgery.

Aim: The aim of the project was to discover if bacteria were implicated in non-union of fractures of the tibia and femur, which had been treated with intramedullary nailing.

Method: 40 intramedullary nails removed from tibial and femoral fractures were retrieved for the purpose of the study. 20 of these nails were from fractures, which had successfully united and were removed for mainly anterior knee pain or discomfort at screw sites. These nails formed the control group for the project. 20 nails were removed from fractures which had failed to unite prior to further operative intervention such as exchange nailing or the application of an Ilizarov frame. These fractures had no clinical evidence of infection and formed the study group for the project. The nails were subjected to ultrasound in the research laboratory to dislodge adherent bacterial formed as biofilm from the surface of the nail. Using both standard culture techniques and non-culture techniques, any dislodged bacteria were isolated and identified. Non-culture techniques involved the use of specific monoclonal antibody labelled immunofluorescence microscopy. Isolated bacteria were tested for the sensitivities of commonly used antibiotics in orthopaedic practice according to NCCLS guidelines.

Results: We discovered that bacteria were detected in up to 70% of the nails removed from fractures, which had failed to unite, using both standard culture and non-culture techniques. Also, we discovered that bacteria were detected in up to 30% of the nails removed from fractures that had united. The organisms identified were mainly the coagulase negative staphylococcus epidermidis and the gram-positive anaerobe proprionibacterium acnes. The antibiotics gentamicin, erythromycin, cefotaxime and cefomandole performed poorly against the isolated bacteria. Vancomycin, ciproxin and fucidin however performed better.

Conclusion: Bacteria formed as biofilm on intramedullary nails may have a significant role in the development of non-union fractures treated by this method. The bacteria isolated showed worrying resistance to commonly used antibiotics in orthopaedic practice, in particular, those used as prophylaxis.