Aims

To explore the effect of different types of articulating antibiotic-loaded cement spacers in two-stage revision for chronic hip prosthetic joint infection (PJI).

Metal-on-metal resurfacing of the hip (MoMHR) has enjoyed a resurgence in the last decade, but is now again in question as a routine option for osteoarthritis of the hip. Proponents of hip resurfacing suggest that its survival is superior to that of conventional hip replacement (THR), and that hip resurfacing is less invasive, is easier to revise than THR, and provides superior functional outcomes. Our argument serves to illustrate that none of these proposed advantages have been realised and new and unanticipated serious complications, such as pseudotumors, have been associated with the procedure. As such, we feel that the routine use of MoMHR is not justified.

Cite this article: Bone Joint J 2014;96-B(11 Suppl A):17–21.

While an increasing amount of arthroplasty articles report comorbidity measures, none have been validated for outcomes. In this study, we compared commonly used International Classification of Diseases-based comorbidity measures with re-operation rates after total hip replacement (THR). Scores used included the Charlson, the Royal College of Surgeons Charlson, and the Elixhauser comorbidity score. We identified a nationwide cohort of 134 423 THRs from the Swedish Hip Arthroplasty Register. Re-operations were registered post-operatively for up to 12 years. The hazard ratio was estimated by Cox’s proportional hazards regression, and we used C-statistics to assess each measure’s ability to predict re-operation. Confounding variables were age, gender, type of implant fixation, hospital category, hospital implant volume and year of surgery.

In the first two years only the Elixhauser score showed any significant relationship with increased risk of re-operation, with increased scores for both one to two and three or more comorbidities. However, the predictive C-statistic in this period for the Elixhauser score was poor (0.52). None of the measures proved to be of any value between two and 12 years. They might be of value in large cohort or registry studies, but not for the individual patient.

Cite this article: Bone Joint J 2013;95-B:1184–91.

We evaluated triple-phase bone scintigraphy in the differential diagnosis of peri-prosthetic infection in 46 patients with a total hip replacement or bipolar hemiarthroplasty who were due for revision surgery. There were 18 men and 28 women, with a mean age at operation of 64.6 years (28 to 81). We defined peri-prosthetic infection as an increased uptake of radioisotope in all the phases of triple-phase bone scintigraphy and validated these results against the histological and/or microbiology results in every case.

The positive and negative predictive values for the presence of infection were 83% and 93%, respectively. The diagnostic sensitivity was 88% and the specificity was 90%.

This study indicates that triple-phase bone scintigraphy is a useful tool in the detection of peri-prosthetic infection and offers a cost-effective method of screening.

Metal-on-metal hip bearings are being implanted into younger patients. The consequence of elevated levels of potentially carcinogenic metal ions is therefore a cause for concern. We have determined the levels of cobalt (Co), chromium (Cr), titanium (Ti) and vanadium (Va) in the urine and whole blood of patients who had had metal-on-metal and metal-on-polyethylene articulations in situ for more than 30 years. We compared these with each other and with the levels for a control group of subjects.

We found significantly elevated levels of whole blood Ti, Va and urinary Cr in all arthroplasty groups. The whole blood and urine levels of Co were grossly elevated, by a factor of 50 and 300 times respectively in patients with loose metal-on-metal articulations when compared with the control group. Stable metal-on-metal articulations showed much lower levels. Elevated levels of whole blood or urinary Co may be useful in identifying metal-on-metal articulations which are loose.