A systematic review of the evidence for single stage and two stage revision of infected knee replacement

BACKGROUND: Periprosthetic infection about the knee is a devastating complication that may affect between 1% and 5% of knee replacement. With over 79 000 knee replacements being implanted each year in the UK, periprosthetic infection (PJI) is set to become an important burden of disease and cost to the healthcare economy. One of the important controversies in treatment of PJI is whether a single stage revision operation is superior to a two-stage procedure. This study sought to systematically evaluate the published evidence to determine which technique had lowest reinfection rates. METHODS: A systematic review of the literature was undertaken using the MEDLINE and EMBASE databases with the aim to identify existing studies that present the outcomes of each surgical technique. Reinfection rate was the primary outcome measure. Studies of specific subsets of patients such as resistant organisms were excluded. RESULTS: 63 studies were identified that met the inclusion criteria. The majority of which (58) were reports of two-stage revision. Reinfection rated varied between 0% and 41% in two-stage studies, and 0% and 11% in single stage studies. No clinical trials were identified and the majority of studies were observational studies. CONCLUSIONS: Evidence for both one-stage and two-stage revision is largely of low quality. The evidence basis for two-stage revision is significantly larger, and further work into direct comparison between the two techniques should be undertaken as a priority

Backside Wear in Modern Total Knee Designs

Although modularity affords various options to the orthopedic surgeon, these benefits come at a price. The unintended bearing surface between the back surface of the tibial insert and the metallic tray results in micromotion leading to polyethylene wear debris. The objective of this study was to examine the backside wear of tibial inserts from three modern total knee designs with very different locking mechanisms: Insall-Burstein II® (IB II®), Optetrak®, and Advance®. A random sample of 71 inserts were obtained from our institution’s retrieval collection and examined to assess the extent of wear, depth of wear, and wear damage modes. Patient records were also obtained to determine patient age, body mass index, length of implantation, and reason for revision. Modes of wear damage (abrasion, burnishing, scratching, delamination, third body debris, surface deformation, and pitting) were then scored in each zone from 0 to 3 (0 = 0%, 1 = 0–10%, 2 = 10–50%, and 3 = >50%). The depth of wear was subjectively identified as removal of manufacturing identification markings stamped onto the inferior surface of the polyethylene. Both Advance® and IB II® polyethylene inserts showed significantly higher scores for backside wear than the Optetrak® inserts. All IB II® and Advance® implants showed evidence of backside wear, whereas 17% (5 out of 30) of the retrieved Optetrak® implants had no observable wear. There were no significant differences when comparing the depth of wear score between designs. The locking mechanism greatly affects the propensity for wear and should be considered when choosing a knee implant system

Poorer survival after a primary implant during revision total knee arthroplasty

<p>Revision total knee arthroplasty (rTKA) is a complex procedure. Depending on the degree of ligament and bone damage, either primary or revision implants are used. The purpose of this study was to compare survival rates of primary implants with revision implants when used during rTKA.</p><p>A retrospective comparative study was conducted between 1998 and 2009 during which 69 rTKAs were performed on 65 patients. Most common indications for revision were infection (30 %), aseptic loosening (25 %) and wear/osteolysis (25 %). During rTKA, a primary implant was used in nine knees and a revision implant in 60.</p><p>Survival of primary implants was 100 % at one year, 73 % [95 % confidence interval (CI) 41-100] at two years and 44 % (95 % CI 7-81) at five years. Survival of revision implants was 95 % (95 % CI 89-100) at one year, 92 % (95 % CI 84-99) at two years and 92 % (95 % CI 84-99) at five years. Primary implants had a significantly worse survival rate than revision implants when implanted during rTKA [P = 0.039 (hazard ratio = 4.56, 95 % CI 1.08-19.27)].</p><p>Based on these results, it has to be considered whether primary implants are even an option during rTKA.</p>