Ion analysis: Serum was collected from test station and allowed to settle for 12 hours. An aliquot of 20 ml from lubricant was collected. Each sample was centrifuged at 2500 g-force for 10 minutes. A 10 ml aliquot was collected from each sample and was further centrifuged at 2500 g-force for 10 minutes. 1.5 ml aliquot was collected and stored at −20 °C. A high resolution inductively-coupled plasma mass spectrometry instrument (ELEMENT, ThermoFinnigan MAT, Bremen/Germany) was then used for the analysis of metal ions.
Hip simulators have been used for ten years to determine the tribological performance of large-head metal-on-metal devices using traditional test conditions. However, the hip simulator protocols were originally developed to test metal-on-polyethylene devices. We have used patient activity data to develop a more physiologically relevant test protocol for metal-on-metal devices. This includes stop/start motion, a more appropriate walking frequency, and alternating kinetic and kinematic profiles. There has been considerable discussion about the effect of heat treatments on the wear of metal-on-metal cobalt chromium molybdenum (CoCrMo) devices. Clinical studies have shown a higher rate of wear, levels of metal ions and rates of failure for the heat-treated metal compared to the as-cast metal CoCrMo devices. However, hip simulator studies in vitro under traditional testing conditions have thus far not been able to demonstrate a difference between the wear performance of these implants. Using a physiologically relevant test protocol, we have shown that heat treatment of metal-on-metal CoCrMo devices adversely affects their wear performance and generates significantly higher wear rates and levels of metal ions than in as-cast metal implants.
Arthroscopic surgery is a common intervention for osteoarthritis of the knee. However, the benefits from such an intervention are not clear. The purpose of the study was to perform a questionnaire survey of orthopaedic surgeons of Wales to analyse the practice of arthroscopy for osteoarthritic knee. Over a three-month period, a postal survey was conducted of all hospital orthopaedic consultants in Wales. Of a total of 62 questions sent we received a reply of 37. 31 surgeons perform arthroscopic lavage or debride-ment. 4 surgeons perform arthroscopic surgery for symptomatic meniscal tear only. There was no defined protocol regarding the management. Early OA was the commonest indication (18). Arthroscopic lavage (17) was equally popular to lavage and debridement (16). 6 respondents like to perform the surgery themselves while the majority would allow a middle grade surgeon to operate with or without supervision. 26 surgeons felt that the results of the procedure are unpredictable, but still continued to perform it. Only 6 surgeons felt a continued relevance of the procedure. Arthroscopic surgery is a commonly performed symptomatic treatment for arthritic knee. It bears a significant financial commitment. 266 arthroscopic knee surgery were performed annually in a district general hospital, of whom 115 were arthroscopic washout. Average cost of each operation is £1000. The physiological basis for arthroscopic washout is not clear. A majority of the Welsh surgeons have reservations about this procedure. In spite of evidence of limited usefulness, it is still performed widely.
To evaluate one-year mortality rate of hip fractures treated surgically and assess the influence of medical status and ASA grade on this parameter. 212 patients above 65 years (range 65–100, mean 82.7): There were 104 (49.1%) intertrochanteric and 108 (51.9%) femoral neck fractures. A number of surgical procedures, (sliding/compression screw 104 (49.1%), hemiarthroplasty 81 (38.2%), cannulated screws 18 (8.5%) and total hip replacement (4.2%) were used. The one - year mortality rate was obtained from computerised records, case notes and General Practitioners. One-year mortality rate for the whole group was 28.8% with an exponential increase corresponding to ASA grade. The relationship between ASA grade and mortality for the whole group (P<
0.001), younger age group of 65 – 84 years (P<
0.001), older age group of 85– 100 years (P=0.002), early operation group <
2 days (P=0.001), females (P=0.000), intertrochanteric fractures (P=0.007), femoral neck fractures (P=0.022) and sliding/compression screw (P=0.007) was highly significant. The type of operation per se and time of operation had no predictive value.
The extensive dominant influence of ASA grade is a highly significant predictive determinant and final arbiter of surgical risk and mortality in hip fracture.