Revue de chirurgie orthopédique et réparatrice de l'appareil moteur
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Rev Chir Orthop Reparatrice Appar Mot · Dec 2002
[In vitro analysis of the continuous active patellofemoral kinematics of the normal and prosthetic knee].
In vitro experiments are particularly useful for studying kinematic changes from the normal knee to experimental conditions simulating different disease states. We developed an experimental protocol allowing a kinematic analysis of the femorotibial and femoropatellar joints in the healthy knee and after implantation of a knee prosthesis, according to the central pivot during simulated active loaded movement from the standing to sitting position. ⋯ The experimental set up enables a comparison of the kinetics of a normal knee with the kinetics observed after implantation of a prosthesis on the same knee. Implantation of a unicompartmental medial prosthesis, leaving the posterior cruciate ligament intact and irrespective of the status of the anterior cruciate ligament, did not, in these experimental conditions, exhibit any significant difference in the femorotibial or femoropatellar kinetics compared with the same normal knee. Implantation of a total knee prosthesis had a significant effect on the femoropatellar kinematics, compared with the same knee before implantation. The main anomalies were related to the medial-lateral rotation of the patella which exhibited an abnormal lateral rotation, possibly favorable for subluxation; these changes were directly related to femorotibial rotation after implantation of the total prosthesis and appeared to be related to the symmetry of the femoral condyles of the prosthesis model studied, perturbing the normal automatic rotation of the knee. There is thus a strong relationship between femorotibial and femoropatellar kinetics in the total knee prosthesis.
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Rev Chir Orthop Reparatrice Appar Mot · Dec 2002
[Isolated traumatic serratus anterior muscle palsy].
The serratus anterior, innervated by the long thoracic nerve, participates in shoulder abduction and elevation, stabilizing the scapula on the rib cage. Paralysis of the serratus anterior prohibits shoulder abduction and elevation beyond 90 degrees and elevation of the spinal border of the scapula. We report our experience with traumatic serratus anterior palsy. ⋯ Several types of treatment have been proposed for serratus anterior palsy: non-operative care, muscle transfers mainly with pectoralis major flaps, and scapulothoracic arthrodesis. Most of the series on scapulothoracic arthrodesis have concerned fascioscapulohumeral dystrophy and cannot be compared with our patients. Data in the literature on muscle transfers, which could be considered as comparable with our trauma injuries, have demonstrated good results for shoulder motion but a limited effect on overall muscle force. In our series, scapulothoracic arthrodesis provided good results for muscle force, pain relief, and overall shoulder function, with shoulder motion being limited by the position of the arthrodesed scapula. We propose this type of treatment for serratus anterior palsy mainly for manual laborers.
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Rev Chir Orthop Reparatrice Appar Mot · Dec 2002
[Validation of an experimental protocol of an optoelectronic analysis of continuous active knee kinematics in vitro].
In vitro experiments are particularly useful for studying kinematic changes in the normal knee exposed to experimental conditions simulating different disease states. We developed an experimental protocol allowing a kinematic analysis of the femorotibial and femoropatellar joints in healthy knees and after implantation of a knee prosthesis, using a central pivot to simulate active loaded movement from the standing to sitting position. ⋯ This experimental setup enables a comparison of the kinetics of a normal knee with the kinetics observed after implantation of a prosthesis on the same knee. The kinetic analysis does not involve a succession of static states but rather a continuous movement generated by the action of the quadriceps that can be loaded, simulating partial weight bearing. Using the markers fixed directly on the bones, this in vitro study allowed remarkably precise and reproducible measurements. The movements simulated regularly encountered clinical situations. The quality of the movement recorded for a given prosthesis thus provides an accurate approach to the quality of the prosthesis. The goal is not to define the exact kinematics of the normal knee but rather to compare the kinematics of the normal knee with that of the same knee after prosthesis implantation allowing an accurate method for assessing prosthesis design and studying the influence of different parameters, particularly the ligaments. Concomitant study of femorotibial and femoropatellar kinematics provides further information rarely found in the literature.
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Rev Chir Orthop Reparatrice Appar Mot · Dec 2002
[Transfusion of recuperated blood in total knee arthroplasty].
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. ⋯ 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.
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Rev Chir Orthop Reparatrice Appar Mot · Dec 2002
[Influence of the height of the joint space on the three-dimensional kinetics of total knee prostheses and behavior of the lateral ligaments: an in vitro study].
The level of the joint space can be modified after implantation of a total knee prosthesis. Likewise, ligament balance is a cardinal point of the surgical technique. The purpose of this in vitro work was to study the influence of the position of the distal tibiofemoral joint space after implantation of a total knee prosthesis on the three-dimensional kinetics of the knee joint and on the behavior of the lateral ligaments. ⋯ The position of the joint space must be rigorously reproduced during TKA not only to maintain correct femorotibial kinematics, but most importantly to preserve patellar kinematics and proper behavior of the lateral ligaments. Ideally, the height of the joint space should be restored first, followed by control of the ligament balance. An over- or undercut of the femur can lead to defective femoropatellar kinematics and ligament tension at flexion despite good ligament balance at extension. In addition, ligament balance should not be achieved by displacing the tibial cut or by modifying the thickness of the tibial component, which would have an effect not only at extension but also at flexion.