The MHRA guidelines for metal on metal (MOM) suggest cobalt and chromium levels of more than 7ppb as potential for soft tissue reaction. However, in some patients soft tissue reaction is seen even in the presence of normal serum metal ions levels. A prospective review of all patients who had metal-on-metal hip arthroplasty was done. Patients who had both serum metal ion levels and MARS MRI scan were included in this study.Introduction
Methods
Total knee replacement (TKR) can be associated with significant post-operative blood loss requiring blood transfusion and haematinics. With increase in the use of navigation for total knee replacement, it is anticipated the blood loss may be lower as the medullary cavity is not breached. Hence, a prospective study was performed to compare the blood loss and the transfusion rates between patients with navigated and conventional total knee replacement. Between September 2006 and December 2009, nearly 100 patients underwent total knee replacement by a single surgeon. Patients who underwent revision total knee replacement and complex primary total knee replacement were excluded. There were 73 patients with an average age of 70.3 (47-91) years. There were 37 males and 36 females with an average BMI of 30. Thirty eight patients underwent navigated TKR and 35 patients conventional TKR. Left knee was replaced in 29 patients, right knee in 40 patients and 4 patients underwent non-simultaneous bilateral total knee replacements. Cruciate retaining prosthesis was used in 17 patients and cruciate substituting prosthesis in 56 patients. Patella was not replaced in any patient. The average pre-operative haemoglobin was 13.26 (8.7-18.4) g/dl in the navigated group and 13.47 (9.6-15.8) g/dl in the conventional group. The average tourniquet time was 110(90-150) minutes in the navigated group and 96.7(60-145) minutes in the conventional group. Seven patients in the navigated group and 3 patients in the conventional group did not have documentation of the tourniquet time. The average post-operative haemoglobin in the navigated group was 10.34 (7.5-14.8) g/dl and 10.03 (7.5-12.2) g/dl in the conventional group. Six patients each in the navigated group and conventional group required blood transfusion. Six patients in the navigated group and 8 patients in the conventional group were started on haematinics. This study does not show any significant difference in the blood loss as estimated by the average drop in the post-operative haemoglobin between navigated and conventional total knee replacement. There was also no difference in the rates of blood transfusion between both the groups. However the average operative time was marginally higher in the navigated group than the conventional group.
