Redefining knee replacement (original) (raw)
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The Journal of Arthroplasty, 2011
We measured the optimal rotational alignment of the tibial component with respect to anatomic landmarks. Kinematic data were collected from functional maneuvers simulated in 20 cadaveric knees mounted in a joint simulator. The axis of knee motion was calculated for squatting and lunging activities over the interval of 30°to 90°of knee flexion. We then examined the accuracy and variability of 5 different anatomic axes in predicting the direction of knee motion. No one landmark guaranteed correct alignment of the tibial component and most predictors were highly variable (range, 6°-21°). The most accurate indicators were the medial third of the tibial tubercle (average error: squatting: 3.5°external rotation; lunging: 9.5°), and the medial-lateral axis of the resected tibial surface (6.7°and 1.1°internal rotation). The correct alignment of the tibial component can be best achieved by splitting the difference between these landmarks to eliminate placement of the component in excessive external and excessive internal rotation.
The effect of distal femur bony morphology on in vivo knee translational and rotational kinematics
Knee Surgery, Sports Traumatology, Arthroscopy, 2012
Purpose Tibio-femoral kinematics are clearly influenced by the bony morphology of the femur. Previous morphological studies have not directly evaluated relationships between morphology and knee kinematics. Therefore, the purpose of this study was to examine the relationship between distal femur bony morphology and in vivo knee kinematics during running. It was hypothesized that the posterior offset of the transcondylar axis would be related to the magnitude of anterior/posterior tibio-femoral translation and that the rotational angle of the transcondylar axis would be related to the magnitude of internal/external knee rotation. Methods Seventeen contralateral (uninjured) knees of ACL-reconstructed patients were used. Distal femoral geometry was analyzed from 3D-CT data by determining the anteroposterior location (condyle offset ratio-COR) and rotational angle (condylar twist angle-CTA) of the femoral transcondylar axis. Six degree-of-freedom knee kinematics were obtained during running using a dynamic stereo radiograph system. Knee kinematics were correlated with the femoral morphologic measures (COR and CTA) to investigate the influence of femoral geometry on dynamic knee function. Results Significant correlations were identified between distal femur morphology and knee kinematics. Anterior tibial translation was positively correlated with the condyle offset ratio (R 2 = 0.41, P \ 0.01). Internal tibial rotation was positively correlated with the condylar twist angle (R 2 = 0.48, P \ 0.01). Conclusions Correlations between knee kinematics and morphologic measures describing the position and orientation of the femoral transcondylar axis suggest that these specific measures are valuable for characterizing the influence of femur shape on dynamic knee function. Level of evidence III.
Gait kinematic analysis of the osteoarthritic knee : pre- and post- total knee arthroplasty
2015
Pour l'honneur qu'il m'a fait pour sa participation à mon jury de thèse en qualité de rapporteur de mon travail, pour le temps consacré à la lecture de cette thèse. Je suis particulièrement honorée de sa présence dans ce jury de soutenance. Je lui exprime ici ma plus haute considération. Monsieur le Professeur Frédéric Farizon Pour avoir accepté d'être rapporteur et membre de jury de cette thèse. Je le remercie pour l'intérêt et la considération qu'il a porté à ces travaux. Je lui adresse mes sincères remerciements ainsi que ma profonde gratitude. Monsieur le Professeur Philippe Neyret, Je tenais à vous remercier de l'accueil que vous m'avez réservé et du temps que vous m'avez consacré lors de mon parcours professionnel. Cette expérience sera très importante pour ma carrière et les tâches auxquelles vous m'avez associée m'ont vraiment permis de consolider mes connaissances et d'en développer de nouvelles. Monsieur le Professeur Sébastien Lustig, Sans vous, cette thèse n'aurait pas été possible. Je vous remercie pour votre patience et vos encouragements qui m'ont portée dans les moments difficiles, pour vos idées et suggestions PLAN ABSTRACT CHAPTER I. INTRODUCTION Hill, Iwaki and coworkers [10] applied MRI scans to 13 unloaded knees and 7 loaded knees for the description of the surface geometry and relative movements of the femur and the tibia. According to this study, during flexion in the unloaded knee, medially, the mean AP position of the femoral condyle did not change from 110° to-5°. Laterally, the femoral condyle rolled
Changes in Knee Kinematics Reflect the Articular Geometry after Arthroplasty
Clinical Orthopaedics and Related Research, 2008
We hypothesized changes in rotations and translations after TKA with a fixed-bearing anterior cruciate ligament (ACL)-sacrificing but posterior cruciate ligament (PCL)-retaining design with equal-sized, circular femoral condyles would reflect the changes of articular geometry. Using 8 cadaveric knees, we compared the kinematics of normal knees and TKA in a standardized navigated position with defined loads. The quadriceps was tensed and moments and drawer forces applied during knee flexion-extension while recording the kinematics with the navigation system. TKA caused loss of the screw-home; the flexed tibia remained at the externally rotated position of normal full knee extension with considerably increased external rotation from 63°to 11°extension. The range of internal-external rotation was shifted externally from 30°to 20°extension. There was a small tibial posterior translation from 40°to 90°flexion. The varus-valgus alignment and laxity did not change after TKA. Thus, navigated TKA provided good coronal plane alignment but still lost some aspects of physiologic motion. The loss of tibial screwhome was related to the symmetric femoral condyles, but the posterior translation in flexion was opposite the expected change after TKA with the PCL intact and the ACL excised. Thus, the data confirmed our hypothesis for rotations but not for translations. It is not known whether the standard navigated position provides the best match to physiologic kinematics.
Kinematics of the knee at high flexion angles: An in vitro investigation
Journal of Orthopaedic Research, 2004
Restoration of knee function after total knee, meniscus, or cruciate ligament surgery requires an understanding of knee behavior throughout the entire range of knee motion. However, little data are available regarding knee kinematics and kinetics at flexion angles greater than 120" (high flexion). In this study, 13 cadaveric human knee specimens were tested using an in vitro robotic experimental setup. Tibia1 anteroposterior translation and internal-external rotation were measured along the passive path and under simulated muscle loading from full extension to 150" of flexion. Anterior tibial translation was observed in the unloaded passive path throughout, with a peak of 31.2 k 13.2 mm at 150". Internal tibial rotation increased with flexion to 150" on the passive path to a maximum of 11.1 f 6.7". The simulated muscle loads affected tibial translation and rotation between full extension and 120" of knee flexion. Interestingly, at high flexion, the application of muscle loads had little effect on tibial translation and rotation when compared to values at 120". The kinematic behavior of the knee a t 150" was markedly different from that measured at other flexion angles. Muscle loads appear to play a minimal role in influencing tibial translation and rotation at maximal flexion. The results imply that the knee is highly constrained at high flexion, which could be due in part to compression of the posterior soft tissues (posterior capsule, menisci, muscle, fat, and skin) between the tibia and the femur.
Journal of Orthopaedic Surgery and Research, 2023
Background The aim of this magnetic resonance imaging (MRI) study was to investigate controversial sexual dimorphism of the posterior condylar offset of the femur (the offset) and the posterior slope of the tibia (the slope) in non-arthritic knees of Egyptian adults. Methods On 100 male and 100 female MRIs of non-arthritic knees, linear measurements of the distal part of the femur (the offset) and the angular measurements of the proximal part of the tibia (the slope) were performed and compared regarding sex and ethnicity. The intraclass correlation coefficient (ICC) was used to test the interrater agreement. Results Both offsets and the lateral offset ratio were larger in males (p < 0.001), the medial offset ratio, and the medial slope in females (p from < 0.001 to 0.007), whereas the lateral slope was sex-free (p = 0.41). Irrespective of sex, however, the medial offset with its ratio, and the medial slope were larger than their counterparts (p < 0.001). Our means of the offsets, their ratios, and the slopes mostly differed from those of other ethnicities (p from ≤ 0.001 to 0.004). ICCs > 0.8 proved MRI's precision was high. Conclusion There was a sexual dimorphism of both the offset and the medial slope in non-arthritic knees of Egyptian adults. We believe future designs of knee implants should consider these differences in order to improve postoperative range of motion and patients' satisfaction after total knee arthroplasty.
In vivokinematics of total knee arthroplasty: Flat compared with concave tibial joint surface
Journal of Orthopaedic Research, 2000
This study evaluated the influence of the geometric configuration of the tibial joint area on the kinematics of the knee. Twenty-two patients with noninflammatory arthritis and minor preoperative deformity were studied. They each received an AMK total knee replacement with retention of the posterior cruciate ligament. Eleven patients without any knee abnormalities were used as controls. The patients were stratified to either the flat (terminology of the manufacturer: standard) or concave (terminology of the manufacturer: constrained) polyethylene insert (n = 11 in each group). Knee kinematics were assessed 1 year after the operation by having the patient ascend a platform corresponding to an extension of the knee from 50 to 70" of flexion. During this motion, two film-exchangers simultaneously exposed six to 13 pairs of serial stereoradiographs. The concave geometric configuration of the tibial insert resulted paradoxically in increased anterior-posterior translations compared with the flat insert but no significant change of rotations and translations in the other directions. Compared with normal knees, the most obvious abnormality was increased anterior-posterior translations (p < 0.004). At SO" of flexion, the implants with the flat tibial polyethylene insert had displaced 2 times and the concave ones had displaced 2.5 times more posteriorly than the normal knees (p 5 0.001). Less internal tibial rotation was also recorded in the flexed positions for both types of inserts compared with the normal knees (p < 0.02). Four knees in four patients, who reported symptoms of instability and abnormal knee function, showed significantly increased proximal displacement of the center of the tibial plateau in the flexed position. The findings suggest that current prosthetic designs and surgical technique do not restore normal knee kinematics and indicate that design improvements should rely on in vivo kinematic studies. ~ Recently, more conforming total knee replacement designs have become popular due to concerns about high contact stresses resulting in wear and delamination of the polyethylene (6,23,26). The choice of joint design and the degree of constraint also influence the kinematics and thereby the function of the knee joint. Previous studies have shown that total knee replacements are associated with abnormal kinematics (2.5, 24,25). Nilsson et al. studied the kinematics of the Tricon knee (15) and found anterior-posterior translations approximately double those of normal knees. This finding was attributed to insufficient function of the posterior cruciate ligament. Later, the same abnormality was noted in other designs that spared the posterior cruciate ligament (14J6). These previous studies used dynamic methods with limited resolution or were based on static measurements. Many were done with the patient in the supine or prone position. Few studies used a randomized de
The Journal of Arthroplasty, 2014
Long term satisfaction of patients with total knee arthroplasty (TKA) has lagged behind that of total hip arthroplasty. One possible reason is the failure of the artificial joint to recreate natural kinematics of the knee. This study evaluated the pre and post implant functional flexion axis in the knees of 285 total knee arthroplasty patients using a surgical navigation system. Results showed that post-implant there was less femoral rollback early in flexion on the lateral side of the joint than pre-implant. Designing future generations of knee implants to allow for this motion may give patients a more 'natural' feeling knee and may benefit outcomes.
Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA, 2014
The purpose of this study was to investigate the hypothesis that a medial unicompartmental knee arthroplasty might restore the functional flexion axis of a knee to normal. The flexion axis can be indirectly identified by tracking the vertical translation of anatomic landmarks that basically move around the flexion axis during a knee motion. If a unicompartmental knee could help restore the normal flexion axis, the anatomic landmarks after the arthroplasty would show the vertical translation similar to those of normal knees during a knee flexion. While performing a squatting motion, the kinematics of 17 knees were determined before and after a medial unicompartmental arthroplasty to calculate the vertical translation of a clinical epicondylar axis, using a three- to two-dimensional registration technique through a single-plane fluoroscopic system incorporating a biplanar static radiography. The results were compared with a normal data, and a statistical analysis including a two-way r...