Abstract
INTRODUCTION
Revision knee arthroplasty is increasing and in 2010 constituted 6% of knee replacements done in the UK according to the National Joint Registry1. Infection was the 2nd most common cause accounting for 23% of the revision burden1. Two-stage revisions are considered the gold standard with success rates from 80–100%2. Single-stage revisions are becoming increasingly popular at certain centers with reported benefits of reduced “down-time” for the patient and a decreased financial burden.
OBJECTIVES
The senior author (DSB) has been performing single-stage revisions for infections for over 10 years. We were interested in seeing the success rate for this method and possibly identify factors that would portend a poorer result.
METHODS
We performed a retrospective review of all single-stage revisions performed at our hospital by the senior author (DSB) from January 2001 to December 2010. In total, 340 revision knee arthroplasties were performed. Of these, 13 (4%) single-stage revisions for infections were identified. The case records of these cases were reviewed and details of the revision as well as medical co-morbidities were assessed to see if any of these factors correlated to a poor outcome. In all, there were 8 women: 5 men with a mean age of 70.9 years (range 49–80 years). 1 case was lost to follow-up and 2 died from unrelated conditions. The mean duration of follow-up for the remaining 10 patients was 4.9 years (range from 1.5 to 7 years).
RESULTS
All patients presented with knee pain along with swelling (30%), stiffness (30%), instability (8%). 2 patients had a chronic discharging sinus. Most patients (92%) had at least 1 medical co-morbidity (e.g. steroid use, diabetes, malignancy, Crohn's disease).
The mean time from index surgery to revision was 3.5 years (range 1 to 9 years). The causative microbe identified prior to surgery was MRSA (15%), MSSA (30%), coagulase-negative Staphylococcus (30%), Streptococcus Gp D (8%) and polymicrobial growth (MSSA with Pseudomonas) (8%). In 3 cases, no microbe was identified. Intraoperative findings were extensive scarring of the soft tissue in all cases with single component loosening in 30% and both component loosening in 15%.
Post-operative complications included 1 case of cellulitis, 1 case of chronic regional pain syndrome and 1 case of hemarthrosis. Most cases had excellent ROM at their last follow-up.
The final surgical outcome of the 10 patients at final follow-up were successful infection eradication in 9 (90%) and 1 failure (10%) requiring repeat 2-stage revision. This failure was the only case with a positive polymicrobial culture prior to his surgery growing MSSA with Pseudomonas. Cases in which we failed to identify the causative organism prior to surgery did not appear to impact on the success rate.
CONCLUSION
We submit that a high success rate can be achieved using single-stage revision along with the potential for improved patient functional outcome due to a lack of “down-time” during the interval of the 2-stage revisions. We, however, cannot advocate this to be undertaken by all surgeons as we still accept that the gold standard remains the 2-stage revision.
