When the kneecap does not ride smoothly in the groove of the femur, popping over to one side, or de-railing.

Patellofemoral instability

How TT-TG Distance is measured, and what it means.

Interpretation by the Editor of a 2017 published medical paper studying long term problems in patients whose original patellar dislocations were not surgically managed.

Video demonstrating the J sign

This is the Editor's interpretation of a paper published in the orthopaedic literature in 2016.

An overview by Dr Lars Blond.

Previous articles and videos relating to the procedure of arthroscopic trochleoplasty can be found on this site.

This discussion and video relates to the basic...

The unstable patella - congenital or acquired?

Instability in the patella means that it jumps to the edge or out of the normal track in the femur in which it lies.