Answer:
You can suffer from a leg weakness with either having sudden cramps , or having weak bones aat the knee joint.
Or not having enough muscle tone or low amounts of cartilage
Leg weakness can occur from
- sciatica
- bulging discs in lower back
- leprosy
- nerve palsy of leg (common peroneal nerve injury)
- diabetes
There are a plethora of causes depending on associated symptoms that one could have like back ache (bulging disc), tingling numbness(sciatica), elevated blood sugar (diabetes).