Performing Bilateral Knee replacements simultaneously is a controversial issue with proponents on both sides of the argument. The advantages of simultaneous arthroplasties include the administration of a single anaesthetic, reduced hospital stay and consequent reduced costs. Reuben et al (J. Arthroplasty, 1998) reported a 36% reduction in hospital costs. Patients also have a quicker return to function and Leonard et al (J Arthroplasty 2003) reported a high patient satisfaction rate of 95%.

The primary disadvantages noted in previous studies include an increase in peri operative complications–both cardiac and pulmonary. An increase in mortality figures is perhaps the most serious complication recorded in some studies. Ritter etal (Clin. Orthop. 1997) reported a 30 day mortality rate of 0.99% in bilateral simultaneous TKA as compared to 0.3% in patients who underwent a staged procedure.

Our study comprised a total of 202 patients who underwent bilateral simultaneous total knee replacements at a District General Hospital in Harlow. Harlow is one of the centres involved in the multi centric trials for the PFC Sigma Knee System and is perhaps the only centre in the UK where bilateral simultaneous procedures are carried out in significant numbers. There were 103 males and 99 females. 12 of the patients had Rheumatoid arthritis. 45% of the patients were in the 71–80 years age group, 26% in the 61–70 years age group. The average age across the entire group was 71.3 years. 35% of patients had a BMI of 25–30, 23% a BMI of 30–35, while less than 5% had a BMI of greater than 40. Most patients (44%) were ASA grade 2. The 3 most common co morbidities included hypertension(85%), coronary artery disease(25%) and diabetes mellitus (12%). 90% of the patients had the procedure performed under a General Anaesthetic and Epidural. Tourniquet time ranged from 55–159 minutes. (average 96 minutes). The patella was resurfaced in all patients. Post operatively the average drain collection was 1200 mls(range 7002600mls). Average pre op Hb was 13.8 g/dl, the post op average being 9.7 g/dl. 71% of patients required blood transfusion after surgery (average 2.8 units). Average hospital stay was 12.4 days (range 5–38 days). 6 patients required HDU admission.

Complications: None in 60%; there were 3 deaths in the first 30 days(1.5%), 2 cases of pulmonary embolism(1%); 6 cases of Myocardial Infarction (3%). There were 14 superficial wound infections and 10 patients required wound washouts. An MUA was performed on 8 knees. 2 patients had Revision Knee replacements for infection.

These figures are comparable to those in published literature. We have found Bilateral simultaneous Total Knee replacements to be a safe procedure with quick return to function.

Purpose of Study: To assess the safety of our practice of Bilateral Simultaneous Total Knee Replacements.

Methods: We retrospectively reviewed 202 patients (404 knees) who underwent bilateral simultaneous total knee replacements using the DePuy PFC Sigma Cruciate Sacrificing Endoprosthesis between January 2000 and January 2006. There were 103 males and 99 females with an average age of 71.3 years (range 41–90 years) included. Indication for surgery was Osteoarthritis in 190 patients and Rheumatoid Arthritis in 12 patients. All patients were reviewed at 6 weeks, 1 year and then yearly post surgery.

Results: The average hospital stay was 12.4 days (range 5–38 days) with 6 patients needing HDUadmission post surgery. The average observed blood loss in the drains post surgery was 1200ml (700–2600ml) with an average drop in Haemoglobin of 4.1%, 71% of patients needed a blood transfusion post surgery. Two patients (0.99%) developed a deep vein thrombosis and 2 patients (0.99%) developed a pulmonary embolus.3 (1.48%) deaths were encountered in the immediate post operative period (within 30 days of surgery) and 6 (2.9%) patients suffered a myocardial infarct post surgery.14 (6.9%) patients developed a superficial wound infection of which 10(4.9%) needed a formal washout. 8(3.96%)knees needed a manipulation under anaesthesia for a poor range of movement, and 2(.99%) needed revision total knee replacement for infection.

Conclusion: Bilateral simultaneous total knee replacement is a safe procedure in our experience Complication rates observed comparable to published literature on the subject

Wear debris from metal on metal (M/M) hip resurfacing and metal on polyethylene (M/P) total hip replacements have different biocompatibilities. M/P wear particles have a foreign body effect¹. M/M wear particles cause hypersensitivity², DNA damage^3,4 and white blood cell suppression⁵.

M/P wear debris contains nickel and M/M wear debris contains cobalt. Nickel and cobalt are both heavy metals, required as trace elements for some bacteria but potentially toxic to bacteria in high concentrations.

Cobalt kills Helicobacter Pylori at concentrations as low as 30 ppb⁶, substantially lower than the concentration in prosthetic joints. Nickel/cobalt permease membrane transporters are found in a wide range of microorganisms⁷ including Staphylococcus Aureus and Coagulase Negative Staphylococci, which commonly infect prosthetic joints.

The purpose was to investigate the effects of nanoparticulate wear debris and their heavy metal constituents on bacterial growth.

Samples of Coagulase Negative Staphylococci (CNS), Staphylococcus Aureus and MRSA were cultivated to compare their growth in M/M wear debris, M/P wear debris, nickel, cobalt and control culture mediums over 48 hours. Nickel was toxic to CNS (p=0.006) and MRSA (p=0.048). Cobalt also retarded the growth of all three bacteria. M/M wear debris increased the growth of CNS 183 times at 48 hours (p=0.044), Staphylococcus Aureus and MRSA. M/P wear increased the growth of Staphylococcus Aureus 120 times at 48 hours (p=0.021), CNS and MRSA.

M/M and M/P nanoparticulate wear debris accelerate the rate of growth of common organisms that infect prosthetic hip joints, the clinical significance of which is uncertain. In isolation, the heavy metals contained within wear debris retard bacterial growth, particularly nickel.

Nanoparticulate wear debris does not possess the toxic effects of its constituent metals on bacteria. This reinforces the safety of wear debris but also shows the potential for anti-bacterial effects to be harnessed.

Data is collected prospectively on all patients undergoing total knee replacement at the Princess Alexandra Hospital in Harlow, as part of an on-going research programme. The database commenced in April 1994 and we will be presenting the details of 1114 patients who underwent total knee replacement between April 1994 and December 2000. The early outcomes will be discussed, as well as a particular emphasis on some groups, like simultaneous bilateral total knee replacements& total knee replacements in the elderly population. We will also present the details of the radiological component positioning in total knee replacements and comparison between the radiological alignment achieved between consultant grade and trainee grade surgeons. The effect of surgeon grade on component positioning was tested using factorial analysis of variance. The statistical analysis was performed using StatView4.0 software The main coronal alignment angle was 6.02 degrees and the mean sagittal tibial angle was 87.11 degrees. Our revision rates will also be discussed.