Data from recent AOANJRR shows a higher incidence of acetabular revision for dislocation of THA in uncemented compared to cemented THA (RR 1.59). We hypothesized that a difference in accuracy of component placement may be a factor. We aimed to assess any difference in accuracy between these 2 types of THA.

Patients undergoing navigated THA were prospectively recruited. Choice of uncemented or cemented THA was based on individual surgeon’s routine practice and preference and no adjustments were made for this study. All THAs (Cemented Exeter-21 and uncemented Trident/Secur fit-20) were performed through a posterior approach.

Statistical analysis: the mean and 95% confidence intervals (or median and interquartile range (IQR) for non parametric data) for each measure in both groups. ANOVA and nonparametric Mann-Whitney U test (significance level 5%). Levene’s test for homogeneity, Comparison of frequencies with chi-squared test or Fishers Exact test. Bonferroni correction where necessary.

We demonstrated a significant difference in reproducibility between components. Four of 20 (20%) uncemented cups deviated from the target inclination by 5 degrees or more compared to none of 21 in the cemented group (p=0.048). Seven of the 20 (35%) of the uncemented cups deviated from the target version by 5 degrees or more compared to none of 21 in the cemented group (p=0.003). There was a significant difference between the groups with regard to deviation from planned leg length (p< 0.001). Deviation from target leg length of greater than 5mm was found in 36.4% of the uncemented cases as compared to 8.3% of the cemented cases although due to the small numbers this was not statistically significant (p=0.16).

Statistically significant reduced accuracy of cup placement is demonstrated with uncemented compared to cemented implants. It is harder to control implant positioning in uncemented implants than cemented implants.

Correct component positioning in hip resurfacing is a key determinant for a successful outcome. The aim of the study was to compare the radiographic and perioperative clinical parameters between navigated and non-navigated resurfacing groups and to look at the effect of navigation on the learning curve.

Pre and post operative radiographs were analyzed with respect to neck-shaft angle, implant-shaft angle, notching, lateral position, and cup inclination. The target implant position was to place the femoral component in relative valgus to the neck-shaft angle using the smallest component without notching the femoral neck. The target cup position was 40–45 degrees inclination. Statistical analysis was performed comparing the two groups with respect to implant position, complications and differences between experienced verses inexperienced surgeons.

Data was recorded for 51 patients (24 navigated, 27 conventional). There was no significant difference in implant-shaft angle or presence of notching between the two groups. There were two cases of notching in the non-navigated cohort. Lateral positioning (central placement stem, centering component on shaft) was significantly more accurate for the navigated cases (P< 0. 001). There was no significant difference in cup inclination between the two groups. In the non-navigated group three patients were converted to a total hip replacement (one fracture, one impingement pain, one intra-operative notching) and there was 1 case of medial wall fracture of the acetabulum. There was a 14.8% complication rate for the non-navigated group with no complications in the navigated group. Complications experienced 2.6% vs. training 17.4%. Training navigated 0% vs Training non-navigated 30%; Experienced nav 0% vs. experienced non-navigated 5.5%.

Positioning of the femoral component in the lateral plane and A-P head-neck ratios is significantly more accurate with the use of computer navigation. Navigation allows for a relative valgus implant-shaft angle that is as accurate as conventional jigs. Navigation is useful as a teaching tool with a reduction in the learning curve and better radiographic placement of components.

We reviewed the diagnostic and clinical experience with acute osteomyelitis of the pelvis at Tauranga and Waikato Hospitals.

A retrospective review from a prospectively maintained data base was undertaken looking at all cases of pelvic osteomyelitis between 1988 and February 2003 at the two hospitals. Analysis of the diagnostic pathways, time to diagnosis, blood parameters, organism isolation, and type of imaging was carried out. Subsequent treatment including duration of intravenous antibiotic use was correlated with patient outcome.

There were 15 cases of acute pelvic osteomyelitis treated with an average patient age of 11.9 years. The most common causative organism isolated was Staphylococcus Aureus (S. Aureus) with no cases of MRSA. Inflammatory markers (ESR and CRP ) were elevated in the majority of patients but 75% had a normal white cell count. Blood cultures were positive in 90% of cases.3 patients required surgical drainage ( 1 case of turberculosis, 2 cases of staphylococcus aureus) The average duration of intravenous antibiotic therapy was 10 days with subsequent oral therapy for an average of 4 weeks. The minimum patient follow up was for 3 months, and there was no reoccurrence of infection in any patient. At final review all patients had returned to normal activities

Staphylococcus aureus is the most common causative agent in this population. ESR and CRP are the most useful markers and blood cultures are essential. Most cases can be managed non surgically and a shorter course of intravenous antibiotic therapy in this group was not associated with any adverse outcomes or reoccurrences of infections