Patient selection has always been considered an important criterion in determining the success or failure of a TKA. In the early days of TKA, orthopaedic surgeons and patients were both uncertain as to the long-term outcomes and most TKAs were performed in patients >65 years of age. Since that time, a number of peer-reviewed studies have provided Level III evidence indicating that TKA was a reliable procedure with 91% to 99% survivorship during the first decade and 85% to 97% during the second decade of follow-up. These encouraging TKA results have prompted a growth in TKA utilisation, particularly in younger patients and a move away from procedures such as osteotomy and UKA which have been associated with higher re-operation rates. As a result, over the past decade, the fastest growing TKA patient cohorts have been in the 45–54 (337% increase for females, 271% for males) and 55–64 (260% increase for females and 213% for males) year old patient groups!

The Swedish Knee Arthroplasty Register has followed Swedish TKA patients since 1975 and has provided useful insights with regards the use of knee arthroplasties in younger patients (i.e. an encouraging TKA revision risk reduction from 1976 to 2009, a higher revision rate for UKAs and higher revision rates for both TKAs and UKAs in younger patients). The Australian National Joint Replacement Registry has also found that age adversely affects knee arthroplasty revision rates, noting higher cumulative, ten-year revision rates for both UKA and TKA patients <55 years of age (UKA 25%, TKA 13%) and 55–64 years of age (UKA 17%, TKA 8%) and a 6X greater revision rate for TKA patients <55 compared to those >75 years of age! In addition, although mobile-bearing TKAs have often been promoted for use in younger patients, higher cumulative revision rates were noted for mobile-bearing TKAs (7%) as compared to fixed-bearing TKAs (5%) at 10 years.

In summary, although TKA outcomes have improved with time, the lack of long-term supporting data should prompt surgeons to be cautious in offering TKA to patients with 20 to 40 more years of life expectancy. New TKA bearing couple technologies (ie. cross-linked polyethylenes and improved femoral counterfaces) should be encouraged, but their introduction should not be based on laboratory tests alone, but also supported by safety and efficacy studies in patients and long-term post-market surveillance data.

Obesity is a growing worldwide health issue! In my home country, the percentage of obese Canadians grew from 13.8% in 1979 to 23.1% in 2004. Interestingly, TKA rates have grown substantially during this time frame and obesity seems to have been a major contributor. In a large study, we found that increasing obesity had an exponential effect on TKA rates (i.e. patients with a body mass index >40 having a 33X greater relative risk of receiving a TKA compared to a normal weight patients). This is an important issue, as obese TKA patients have been shown to have greater pre-operative disability, have longer waits for surgery, be associated with greater technical difficulties (i.e. wound healing, infection, ligamentous injury, deep vein thrombosis and medical issues) and have more peri-operative complications. As a result, some countries have advocated deferring TKAs in obese patients until they have lost a substantial amount of weight despite the fact that many studies have demonstrated that the required weight reduction is seldom achieved. In an effort to understand this issue, we have conducted several studies. In a multicentre study, we could find no link between patient obesity and the level of patient satisfaction following a primary TKA. In another mid-term study, we found that obese patients had equal implant survivorship, but did note that obese patients had lower pre-operative and post-operative health-related quality of life outcome scores. However, in this manuscript we advocated determining the ‘improvement or delta score’ (i.e. difference between the pre-operative and post-operative scores) and found that when this was done, obese TKA patients actually demonstrated more improvement than normal and overweight patients!

Based on our research, we would make the following recommendations: (1) the public should be educated on the effect of obesity on TKA rates, (2) weight management should be an important part of non-operative knee arthritis management and (3) TKA should ‘not’ be withheld from obese patients with end-stage knee arthritis.

Purpose

The pros and cons of general anesthesia versus spinal anesthesia in total hip arthroplasty has been a long debated topic. The purpose of this study was to compare the surgical times, blood loss and transfusion requirements between anesthetic types in patients undergoing primary total hip arthroplasty.

Introduction

The new Knee Society Score has been developed and validated, in part, to characterize better the expectations, components of satisfaction, and the physical activities of the younger, more diverse modern population of TKA patients. This study aims to reveal patients' activity levels' post-TKA and to determine how it contributes to their subjective evaluation of the surgery.

Wear of the polyethylene (PE) insert in total knee replacements can lead to wear-particle and fluid-pressure induced osteolysis. One major factor affecting the wear behaviour of the PE insert in-vivo is the surface characteristics of the articulating femoral components. Contemporary femoral components available in Canada are either made of cast Cobalt Chromium (CoCr) alloy or have an oxidized zirconium surface (Oxinium). The latter type of femoral components have shown to have increased abrasive wear resistance and increased surface wettability, thus leading to reduced PE wear in-vitro compared with conventional cast CoCr components. Although surface damage has been reported on femoral components in general, there have been no reports in the literature as to what extent the recommended operating techniques affect the surface tribology of either type of femoral component.

Twenty-two retrieved total knee replacements were identified with profound surface damage on the posterior aspect of the femoral condyles. The femoral components were of three different knee systems: five retrievals from the NexGen(r) total knee system (Zimmer Inc., Warsaw, IN), twelve retrievals from the Genesis II(r) total knee system (CoCr alloy or Oxinium; Smith & Nephew Inc., Memphis, TN), and five retrievals from the Duracon(r) total knee system (Stryker Inc., Mahwah, NJ). Reasons for revision were all non-wear-related and included aseptic loosening in two cases, painful flexion instability, and chronic infection. All retrieved femoral components showed evidence of surface damage on the condyles, at an average of 99° flexion (range, 43° – 135° flexion). Titanium (Ti) alloy transfer and abrasive surface damage were evident on all retrieved CoCr alloy femoral components that came in contact with Ti alloy tibial trays. Surface damage on the retrieved Oxinium femoral components was gouging, associated with the removal and cracking of the oxide and exposure of the zirconium alloy substrate material. CoCr alloy femoral components that had unintended contact with CoCr alloy tibial trays also showed evidence of gouging and abrasive wear.

All femoral components showed severe surface damage in the posterior aspect of the condyles. The femoral surface was heavily scratched and the oxidized zirconium coating surface appeared removed. The surface analysis suggested that the surface damage most likely occurred during the time of initial implantation. In particular, it appeared that the femoral condyles were resting on the posterior aspect of the tibial tray in flexion, thus scratching the femoral components. Such scratches could potentially lead to accelerated PE insert wear and reduced implant longevity, thus making expensive revisions surgery necessary. The authors strongly suggest a revision of the current operating techniques recommended by the implant manufacturer to prevent this type of surface damage from occurring.