Hello and welcome to HealthcareMagic. It is not easy to answer you question without being able to actually see your elbow condition, but what comes to mind and what could be responsible for this is ligament laxity. This means that the ropes which attach to your arms and forearms are a little too long or too stretchy and they allow your elbows to hyperextend . Perhaps your other joints are also very flexible. This dose not mean that this is abnormal. Some people are very flexible - can bent joints more than others. Sometimes there are connective tissue diseases which cause such ligament laxity, and this would need to be evaluated by a doctor. I hope you find my answer helpful. Regards