Hello There.
I can understand your concern.
when the cartilages between the knee joint is fully eroded then any movement becomes difficult be it flexion or extension of the knee joint.
i would suggest you to consult a orthopedician in person in this regards and consider a surgical form of treatment for her if possible.
best regards,
Dr. Anil kumar jain.
Health Tips
if she is overweight, she needs to lose weight also.