Aim: To determine the accuracy of clinical diagnosis in patients undergoing arthroscopic surgery of the knee.

Methods: A retrospective analysis of patients who had undergone knee arthroscopy at the Norfolk and Norwich University Hospital was performed from a prospectively gathered database. Pre-operative diagnosis was compared with operative diagnosis to determine the accuracy, sensitivity and specificity of the clinical diagnosis. The data was then analysed to determine how many patients underwent a beneficial procedure, which was defined as “a procedure from which the patient is likely to have benefited, either as a result of confirming the diagnosis or therapeutic intervention”. Finally, the results were compared with those from studies where the accuracy of MRI was assessed, to determine whether MRI is a more accurate diagnostic modality than clinical examination.

Results: The data of 698 patients was analysed. Of these 64% were male and 36% were female. The mean age at operation was 41 years (9 to 92). The overall accuracy, sensitivity and specificity of clinical diagnosis was 99%, 70% and 99% respectively. 90% of patients underwent a beneficial procedure, while 10% had a normal knee diagnosed at operation. Medial meniscal tear was the hardest pathology to diagnose, with accuracy, sensitivity and specificity rates of 82%, 92% and 79%. The results fell within the range of those found in studies, which examined the accuracy, sensitivity and specificity of MRI.

Conclusion: Our results show that clinical examination remains an accurate method of diagnosing intra-articular pathologies of the knee. Medial meniscal tear appears to be the hardest pathology to diagnose, and was the only condition with an accuracy rate under the 90th percentile. This is probably because medial tibio-femoral articular dysfunction has similar clinical findings. MRI was found to be no more effective than clinical examination at diagnosing pathologies of the knee.

Aim: To identify the microbiology of infected knee arthroplasty, emerging patterns of resistance over the last decade, and suggest appropriate empirical treatment.

Methods: A retrospective analysis was conducted of 121 patients with microbiologically proven infection, who underwent revision TKA between 1994–2008. The causative organism was identified from microbiological samples and the corresponding sensitivities recorded. The data was then collated to determine the most common causative organisms, changing patterns of antibiotic resistance over the time frame, and the antibiotics currently most effective at treating deep infection. A theoretical model combining gentamicin with other antibiotics was used to determine the most effective antibiotics for use as empirical treatments.

Results: Coagulase negative Staphylococcus (CNS) was the most common causative organism (49%). Staphylococcus aureus (SA) accounted for 13% of cases. The prevalence of CNS appears to be increasing, while that of SA and other organisms is decreasing. Vancomycin and teicoplanin were the most effective antibiotics with overall sensitivity rates of 100% and 96% respectively. Levels of resistance were significantly higher among the antibiotics more commonly used in the community. Antimicrobial resistance was higher when the causative organism was CNS, suggesting that multi-drug resistant CNS is becoming a problem in knee arthroplasty. Our theoretical model showed that gentamicin combined with vancomycin would be the most effective empirical treatment.

Conclusion: Understanding the microbiology of deep infection of the knee allows surgeons to treat this complication as effectively as possible. Vancomycin and teicoplanin appear to be the most effective antimicrobials, with relative invulnerability to the development of resistance. Given the effectiveness of these antibiotics, the use of vancomycin in gentamicin bone cement, combined with IV teicoplanin potentially allows for infected knee arthoplasties to be treated with a one-stage procedure. The rational use of antibiotics may help limit the amount of antibiotic resistance which develops in the future.