Glenoid and humeral head bone defects have long been recognized as major determinants in recurrent shoulder instability as well as main predictors of outcomes after surgical stabilization. However, a universally accepted method to quantify them is not available yet. The purpose of the present study is to describe a new CT method to quantify bipolar bone defects volume on a virtually generated 3D model and to evaluate its reproducibility.

A cross-sectional observational study has been conducted. Forty CT scans of both shoulders were randomly selected from a series of exams previously acquired on patients affected by anterior shoulder instability. Inclusion criterion was unilateral anterior shoulder instability with at least one episode of dislocation. Exclusion criteria were: bilateral shoulder instability; posterior or multidirectional instability, previous fractures and/or surgery to both shoulders; congenital or acquired inflammatory, neurological, or degenerative diseases. For all patients, CT exams of both shoulders were acquired at the same time following a standardized imaging protocol. The CT data sets were analysed on a standard desktop PC using the software 3D Slicer. Computer-based reconstruction of the Hill-Sachs and glenoid bone defect were performed through Boolean subtraction of the affected side from the contralateral one, resulting in a virtually generated bone fragment accurately fitting the defect. The volume of the bone fragments was then calculated. All measurements were conducted by two fellowship-trained orthopaedic shoulder surgeons. Each measurement was performed twice by one observer to assess intra-observer reliability. Inter and intra-observer reliability were calculated. Intraclass Correlation Coefficients (ICC) were calculated using a two-way random effect model and evaluation of absolute agreement. Confidence intervals (CI) were calculated at 95% confidence level for reliability coefficients. Reliability values range from 0 (no agreement) to 1 (maximum agreement).

The study included 34 males and 6 females. Mean age (+ SD) of patients was 36.7 + 10.10 years (range: 25 – 73 years). A bipolar bone defect was observed in all cases. Reliability of humeral head bone fragment measurements showed excellent intra-observer agreement (ICC: 0.92, CI 95%: 0.85 – 0.96) and very good interobserver agreement (ICC: 0.89, CI 95%: 0.80 – 0.94). Similarly, glenoid bone loss measurement resulted in excellent intra-observer reliability (ICC: 0.92, CI 95%: 0.85 – 0.96) and very good inter-observer agreement (ICC: 0.84, CI 95%:0.72 – 0.91).

In conclusion, matching affected and intact contralateral humeral head and glenoid by reconstruction on a computer-based virtual model allows identification of bipolar bone defects and enables quantitative determination of bone loss.

Introduction: The aim of study was to evaluate the prevalence of microbiological isolates obtained from patients admitted to a 308-bed university-affiliated adult and children orthopaedic hospital of northern Italy (with more than 16.000 admissions per year), during a three year period (2000–2002), and, to analyze modifications during this period with regard to the prevalence of methicillin-resistant staphylococci strains.

Material and Methods: A retrospective study was conducted using laboratory records from 2000 to 2002 (2003 in progress) concerning bacterial and yeast isolates from all specimens sent to microbiological laboratory for culture. The specimens came from 8 surgical, 1 intensive care, 1 oncologie and 1 physiotherapy wards and included samples taken at surgical intervention, as like as at patient bed. Antimicrobial susceptibility testing results were also collected. All data were stored in an electronic database for statistical analysis.

Results: Between 2000 and 2002 a total of 8302 clinical specimens have been cultured and they yielded to 2978 isolates from 2653 positive samples. The prevalence of positive cultures form 24.8% in 2000 to 36.7% in 2002 and the isolated organisms are shown in table 1. Gram positive bacteria represent more than 70% of isolates and staphylococci are the most common organism (almost 50%). Staphylococcus epidermidis and other coagulase-negative staphylococci prevalence raised during the period 2000–2002 (respectively 25.4% to 33.4%, and 3.3% to 6.5%). Methicillin resistance rate resulted, 27.1% to 34.9% for Staphylococcus aureus, 37.6% to 28% for Staphylococcus epidermidis, and 33.3% to 42.1% for other coagulase-negative staphylococci. No difference in methicillin sensitivity was found between staphylococci isolated from surgical sites and other samples (urine, blood, sputum, throat swab).

Conclusions: Knowledge of the local epidemiology of pathogens in a surgical/orthopaedic hospital is critical in formulating policies on infection control. Amongst these rules the choice of antibiotic prophylaxis should be taken after analysis of bacteria prevalence and their antibiotic sensitivity.