الفهرس 
Introduction
ANATOMY OF THE KNEEOnly 14 pages are availabe for public view
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Abstract
Total Knee Arthroplasty (TKA) considered to be the most common type of arthroplasty performed with 40,675 TKAs done in Australia in 2009(84). The overall satisfaction from TKA procedures irrespective of type and technique can reach up to 95%(85)
Nevertheless, one of the complications and a major reason for patient dissatisfaction after TKA is mal-rotation of the components(87).
A great attention should be paid to adjust the femoral component rotation as it requires adequate knowledge of the distal femur anatomy as well as expertise in the surgical technique.
Although the optimal value of femoral component rotation remains unclear and the best method for assessing this parameter is controversial, Several reference axes have been proposed to establish proper rotational alignment of the femoral component, including the posterior condylar line (PCL) (9), the anteroposterior axis (APA)(the so-called Whiteside’s line)(10, 11), and the trans epicondylar axis(TEA)(4). Of these axes, the trans epicondylar axis also has been shown to approximate the flexion-extension axis of the knee(12)
Rotational mal position of the femoral component during TKA can create a trapezoidal flexion gap that alters knee ligament balance and patellar tracking. There was general agreement that internal rotation of the femoral component is undesirable (67, 88, 89)
The optimal value of femoral component rotation remains unclear and the best method for assessing this parameter is controversial
Posterior condylar angle measurement has been evaluated in several studies as an accurate method for determining the femoral component rotation, CT or a special knee radiograph view had been suggested .
In this study we adopted the method described by Takai et al.(21) reporting the use of a seated A-P radiograph, with the knee in 90◦of flexion. The patient kneels on the radiographic film, with the hip in neutral rotation. The X-ray beam is vertical, centered on the popliteal fossa and perpendicular to the tibial shaft. We found it to be an easy reproducible and accurate method to measure the femoral component rotation as the angle between the TEA and a PCA.
The rotational measurements obtained in this study is consistent with the results obtained by a study done by ,Kanesaku et al., In 2005. (22) after using another method in which the patient is seated with the legs hanging down. The X-ray beam is behind the patient, centered on the popliteal fossa, with a variable degree of obliquity depending on patient build. the mean aPCa was (−6.9o ± 1.4◦) in our results aPCa ranged from 0 to -9 internally rotated distal femur with mean and standard deviation (-4.48o±2.45) . This method showed good reproducibility and proved feasible even in patients with knee pain or instability.
We showed a statistically highly significant correlation between the difference of pre-operative aPCa and the post-operative aPCa in which mean post operative aPCa (-3.66o±2.31)
the relationship of PCL to the a TEA (preoperative) was not significantly affected by the direction of preoperative coronal plane deformity (P = 0.392) ,Patients with valgus deformity had a PCA that was (-5.4o±1.52) degrees internally rotated to the aTEA compared to varus patients whose PCA was (4.43o±2.49)degrees internally rotated, these results were comparable to the results reported by Griffen et al. which demonstrated that valgus knee have more internally rotated aPCa(5.4 ° ± 2.3) than those with varus deformity were aPCa were(-3.3o± 1.9) or with no coronal plane deformity aPCa were (-3.3o±2.3)(78)
In this study, we concluded that a PCa is not affected by age or gender but we found that sever varus deformity can lead to distal femur to be in a more internal rotation position.
So we suggest that in sever deformity cases a great care should be paid to determine the proper landmark to determine the appropriate femoral component rotation and one of the best ways to do so is to follow the PCL and its relation to the TEAFurther work should be done to Compare between gap balance and measured resection technique in determining the femoral component rotational alignment.