الفهرس 
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Abstract
The patella improves the moment arm of the quadriceps, provides an articulation with low friction, protects the distal aspect of the femur from trauma and the quadriceps from attritional wear, and improves the cosmetic appearance of the knee.
During the development of knee arthroplasty varying degrees of attention have been given to the patello-femoral articulation.
Throughout the last decades, patellar resurfacing with knee replacement has been a challenging problem. With implantation of knee prostheses the patella will be subjected to forced movements as a result of altered kinematics of the knee. This could cause compressive, rotatory and shearing forces. Knee replacement may also alter the joint alignment and position and this will be reflected secondarily on the patello-femoral articulation.
The patello-femoral joint, thus, remains the weak point in knee arthroplasty to which up to 50 percent of complaints, complications and re-operations could be attributed.
Many first generation total knee prostheses did not provide for resurfacing of the patello-femoral joint and resulted in residual patello-femoral symptoms.
For these reasons some surgeons carried out patellectomy at time of replacement of tibio-femoral surfaces. It quickly became clear that this procedure led to an unacceptable incidence of complications and therefore, this concept was totally abandoned.