Long-term results of a rotationally unconstrained fixed-bearing total knee prosthesis.

PURPOSE: Introduced in the market in 1990 by Ceraver (France), the posterior-stabilised (PS) Hermes prosthesis has limited literature regarding long-term survivability. The purpose of the study is to evaluate the survival and functional outcomes of the prosthesis. METHODS: A retrospective case series was performed including 164 patients (176 knees) having undergone total knee arthroplasty with the Hermes prosthesis between 1997 and 2000 with a follow-up period of 18 years. RESULTS: Kaplan-Meier analysis showed a survival rate of 99.4% (95% CI. 96.0-100.0%) at 18.4 years with one revision. At final follow-up, the International Knee Society (IKS) functional score was 93.2 ± 15.6 and IKS knee score was 99.1 ± 2.5. CONCLUSION: The Hermes PS model is a low conformity prosthesis that offers reliable durability that is comparable to other popular designs while minimizing rotational constraints and having an approachable learning curve for new users.

[Transfusion of recuperated blood in total knee arthroplasty]. / Transfusion de sang récupéré en postopératoire dans l'arthroplastie totale du genou.

PURPOSE OF THE STUDY: Autologous blood transfusion is not a routine procedure in knee replacement surgery. Several authors have proposed recovering blood shed during the procedure to limit the need for homologous transfusions. The purpose of this retrospective study was to analyze the amount of blood recovered and reinfused with a blood conservation system (MI, USA) and its effect on hemoglobin level five days after surgery in 405 consecutive patients undergoing total knee arthroplasty. MATERIAL AND METHODS: Preoperative intravascular blood volume and hemoglobin level were used to calculate the quantity of hemoglobin transfused expressed in g/dl at time t 0 of transfusion then at day 1 and day 5 postop. Autologous blood transfusion was not programmed for any of these patients. Twenty patients were given homologous blood transfusions and were excluded from the analysis of data on recovered shed blood but were included in the analysis of risk of homologous transfusion. The analysis thus included 385 patients who did not require homologous blood transfusion. Shed blood was reinfused in 337 patients; no transfusion was performed for 48 patients whose drainage produced an insufficient volume. The same analysis was performed for three sub-groups of patients: 205 patients whose transfusion volume was less than 10% of their intravascular volume, 132 patients whose transfusion volume was greater than 10% of their intravascular volume, and 50 transfused patients who weighed less than 70 kg. RESULTS: Mean transfusion volume was 516 ml (range 100-1440 ml), accounting for 59% of the drainage volume over 24 hours and 32% of total estimated blood loss. On the average, the whole blood shed and reinfused contained 60.60 g hemoglobin and increased serum hemoglobin by 0.97 g/dl at day 5 postop (with a wide range: 0.18-2.74 g/dl). Mean transfusion volume, based on hemoglobin equivalent packed cell units, corresponding to 10% of the mean intravascular volume was taken as the threshold of transfusion efficacy. Among the 132 patients whose transfusion volume was greater than 10% of the intra-vascular volume, hemoglobin level at day 5 postop increased 1.32 g/dl on the average. Among the 205 patients whose transfusion volume was less than 10% of the intravascular volume, hemoglobin level on day 5 postop increased 0.74 g/dl on the average. In patients weighing less than 70 kg, transfusion increased hemoglobin level on day 5 postop 1.23 g/dl on the average. The probability of transfusion of more than 10% of the intravascular volume was 0.66 +/- 0.1 in patients weighing less than 70 kg and 0.33 +/- 0.05 for the entire population (p<0.001). The fall in mean hemoglobin level from day 0 to day 5 was 3.46 g/dl in transfused patients and 4.16 g/dl in non-transfused patients (p<0.0001). Reinfusion of shed blood allowed 80 more patients (20% of the 405 patients in this series) to maintain their hemoglobin level above 9 g/dl on day 5 postop. The probability of homologous blood transfusion for serum hemoglobin<8 g/dl was 0.5 +/- 0.08. Applying this probability in a situation without recovery of shed blood, the total number of homologous blood transfusions would have increased from 4.9% to 10.7% (p<0.01). DISCUSSION: Patient follow-up confirmed the absence of specific problems. Mean transfusion volume was 516 ml with a 59% (mean) reinfusion/drainage ratio, in line with data reported in the literature. The efficacy of the blood conservation system was unpredictable due to the wide range of blood volume transfused, and consequently of hemoglobin transfused, related to wide interindividual variability for total blood loss and drainage volume. Since the mean volume of reinfused blood contained the same quantity of hemoglobin as one packed red cell units, it would appear reasonable to take 10% of theoretical intravascular volume as a threshold above which the transfusion method becomes efficacious. CONCLUSION: Considerable interindividual variability in total blood loss and total drainage volume compromises the overall efficacy of blood conservation systems. Increase in hemoglobin level on day 5 postop was vary variable in this series of reinfused knee arthroplasty patients (range 0.18 - 2.74 g/dl) with a mean of 0.97 g/dl which corresponds to one packed red cell unit. The probability that the transfused volume would be greater than 10% of the theoretical intravascular volume was 0.66 +/- 0.1 in patients weighing less than 70 kg versus 0.33 +/- 0.05 for the entire population (p<0.001). This finding would suggest that a blood conservation system should be used routinely in patients weighing less than 70 kg. Conversely, the use of the system as a routine measure for all knee arthroplasty patients with the aim of limiting the risk of homologous blood transfusion to a minimum would divide the risk by two and also avoid the risk of viral contamination and identification errors.

Functional outcome after intertrochanteric fractures of the femur: does the implant matter? A prospective study of 100 consecutive cases.

In a randomized study of 100 consecutive patients with an intertrochanteric fracture of the femur fixed internally either with a sliding hip screw or with a McLaughlin nail-plate, the functional outcome of the 6 months survivors has been analysed. There was no statistically significant difference between the two treatment groups with regard to the rehabilitation progress and recovery to the prefracture walking ability, pain and gait at 6 months. Of the 6 months survivors, 55 per cent whose fractures were unstable and 76 per cent whose fractures were stable regained 90 per cent or more of their individual prefracture walking ability. The incidence of failure by 'cutting-out', the reoperation rate and the mortality at 6 months were not statistically different in the two treatment groups.