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TKR: Femoral Component

- See:
     - TKR Menu
     - Distal Femoral Resection 
     - Femoral IM Alignment Rod 
     - Distal Femoral Sizing Guide (and Rotational Alignment)
     - Anterior, Posterior, and Chamfer Cuts 
     - Femoral Component Notching

- Design Considerations: 
    - PCL Retaining Prosthesis 
    - Posterior Stabilized Prosthesis 
    - left & right vs universal designs, & contact area w/ patellar & tibial components;
    - depth of the patellofemoral groove:
           - adequate depth of the patellofemoral groove to provide patellar stability w/o compromise of integrity of prosthesis or removal
                   of excessive bone stock is important;
          - raising the lateral wall of the patellar flange surface controls patellar tracking, but lowering of the medial side does not prevent
                   lateral subluxation, and therefore there is no mechanical advantage to lowering of the medial patellar flange;
    - proximal extent of anterior flange:
           - adequate proximal extension of anterior flange minimizes chance that patella will ride off flange proximally in full extension;
    - contact area of femoral condyles with the patella and the tibial plateaus;
           - point and line contact suggest excessive contact stress, which may lead to excessive wear of tibial and patellar components;
    - coronal plane alignment: (see distal femoral resection)
           - in the coronal plane, the normal femoral condylar surface is oriented perpendicular to the hip-ankle axis (defined as the line
                    joining center of the hip and the center of the ankle joint (anatomic axis of femur);
           - however, the hip-ankle axis is not practicle, because of problem finding the center of the femoral head;
           - appropriate axial alignment is assured by both intra & extramedullary guides;
           - long cassette, single leg stance, mechanical axis x-ray of leg allows measurement of difference between anatomic &
                    mechanical axis of femur;
           - this measurement may be "dialed" into distal femoral cutting jig (which is located in the medullary canal), so distal femoral
                    cut  may be made at right angles to the neutral mechanical axis
           - high flexion / open box design
                     - ref: Femoral component loosening in high-flexion total knee replacement: an in vitro comparison of high-flexion versus conventional designs.

- Press Fit Condylar Design:
    - femoral component of a total knee is subject to almost entirely to compressive stresses;
           - consequently there have been very few reports of failure of the femoral component;
           - optimum choice of materal relates therefore not to its strength, but rather to its ability to resist corrosion;
           - fixation of femoral component has not been major problem w/ cemented or pressfit TKA, but load transfer can be an issue w/
                        pressfit component

Determining the rotational alignment of the femoral component in total knee arthroplasty using the epicondylar axis.

The effect of femoral component position on the kinematics of total knee arthroplasty

Loosening of the femoral component after unicompartmental knee replacement.

A different fixation of the femoral component in total knee arthroplasty may lead to preservation of femoral bone stock

Upsizing the femoral component increases patellofemoral contact force in total knee replacement

Unique relationship between osteophyte and femoral-tibia component size mismatch in determining polyethylene wear in primary total knee arthroplasty: a case report

Effects of Femoral Component Size on Proximal Tibial Strain With Anatomic Graduated Components Total Knee Arthroplasty

Femoral component sizing in total knee arthroplasty: size matched resection versus flexion space balancing

A Choose the Size of the Femoral Component That Stabilizes the Knee in Flexion