Is there such a thing as a degenerative tendon disease?

Thank you in advance for any insights you can give me regarding my tendon problems.

Is there such a thing as a degenerative tendon disease?  

The reason I ask is that I have experienced tendon problems in multiple locations of my body over the last 5 years.  Granted, dealing with my handicapped daughter has generally been related to the ultimate events that caused the final tearing (e.g., while pulling her pants up, I heard my rotator cuff tear).  And, presumably, the numerous mini-injuries I incurred with her likely caused enough damage so as to lead to the final tearing.  Still, I know many other parents of handicapped children (not to mention caregivers at nursing homes) who have much more physically challenging situations with those they care for yet I rarely find others who have even close to the number of injuries I have experienced (see below).  Thus, I’m wondering if my tendons are simply more prone to injury because of a disease that causes the pre-injury condition of the tendon to be subnormal.  Or, might it indicate a disease that causes the injury to eventually be more severe by not allowing the tendon to heal properly after the injury and/or after surgery?

My history regarding tendons is:  I am a 48-year-old man who over the past 5+ years has torn the inner and outer tendons in both elbows.  3 and 4 years ago, the outer tendons in both elbows were operated on (about 1 year apart).  Nearly two years ago, I had surgery on my right shoulder to remove excess bone in two areas where the tendons needed to be able to slide/move more freely.  However, earlier this year, I torn my rotator cuff in that same shoulder and had to have surgery on it.  The shoulder improved for a short period of time after the surgery but has had a couple setbacks which apparently exasperated the situation.  The shoulder has started to have more pain and, during certain movements, has exhibited more “catching” and “clicks/pops”.  A recent MRI showed that the bursis is enlarged/thickened and there is significant tendonitis in the general area that was operated on although no re-tearing occurred.  Additionally, there is a build up of scar tissue in the area of the operation, which I’m told is not unusual. My surgeon’s physical therapists have been working on my shoulder for over six months to loosen up the scar tissue, among other goals.  While holding my right elbow against my side, I am still unable to rotate my hand and forearm outward to the side while the forearm is in a horizontal position; except when someone moves it for me.  Over the past 4-6 weeks, my left shoulder has started to exhibit some of the same type of pain I had in my right shoulder prior to the final tearing of the rotator cuff - something that is makng me very nervous.  As a youth, I suffered from Osgood-Schlatter in both knees.  A couple months ago, I was going down some stairs and I came down hard on my right foot while twisting my leg a little.  This jarred my right knee pretty badly.  X-Rays showed that I have two bone fragments embedded in the tendon that goes over the kneecap (presumably from onset of the Osgood-Schlatter nearly 40 years ago) plus there is a bone spur sticking straight out into the underside of that tendon, resulting in a reduction of the normal amount of slack the tendon would otherwise have.  Naturally, the bone spur presumably irritates the tendon under certain conditions.  I will be having an MRI of that knee so as to see how much inflammation and possible tearing of the tendon there might be and whether a surgical option may be needed.  Iontal treatments did little to ease the pain and stiffness I experience in the knee while going up and down stairs or from sitting too long with my right leg bent at a fairly typical 90-degree angle.  I have essentially been unable to work at my job since my late-April surgery because sitting at a computer all day causes significant pain and stiffness in my shoulders, primarily the right one but more and more the left one too, and my elbows get very stiff and somewhat painful.  I won’t go into my back and neck problems but they too are very much aggravated from the continual computer work I do regardless of trying everything that doctors, physical therapists, and ergonomic experts have suggested regarding the positioning of my body, chair, desk, and computer equipment.  To sum things up, I have had four operations regarding tendons in the last 4 years plus I had tearing of the inner tendons of both elbows that did not warrant surgery but did require physical therapy.  I may be looking at additional problems with tendons in both shoulders and my knee that may or may not result in surgery.  Boy, do I feel old sometimes.  I occasionally wonder if my girlfriend secretly desires to trade me in for a more medically stable/reliable younger man.     By the way, none of this is meant as a complaint against my surgeon nor am I trying to build a legal case against him.  At this point, I have no reason to think that he is anything other than an honest and skilled cutter.  I doubt that opinion will ever change.