Leg/Arm Problems for Years

[OptoFuture]

I am a 15 year old male diagnosed with Kniest dysplasia. However, through the amount of research I've done, the most debilitating symptom does not appear as a side effect of Kniest dysplasia. This symptom is the inability to straighten out my legs due to my hamstrings. If I try to straighten them, they only go ~90 degrees maximum. Trying to straighten them causes extreme pain in the front of my knees. When I was 5, I had a hamstring lengthening surgery which allowed me too straighten my legs and walks for two years. However those two years were very painful. My knees would often lock up and eventually the locking up turned into immobility. Thus I eventually went into a wheelchair. Now, I am in a wheelchair full time. However, I ask this question now as just recently (2.5 years ago) the joint of my elbow has been exhibiting the same thing. It began to lock up in August 2015 which was very painful. Now, both my arms are experiencing limited mobility. Neither are as limited as my legs, but my left arm is pretty close to equivalency. I am worried as this may hinder my ability to use my arms and I need arms to access things. Thank you for any feedback.