Epidemiology
Rotator cuff tears are among the most common conditions affecting the shoulder.A rotator cuff tear can be caused by the weakening of the rotator cuff tendons. This weakening can be caused by age or how often the rotator cuff is used. Adults over the age of 60 are more susceptible to a rotator cuff tear, with the overall frequency of tears increasing with age. By the age of 50 10% of people with normal shoulders have a rotator cuff tear.In an autopsy study of rotator cuff tears, the incidence of partial tears was 28%, and of complete rupture 30%. Frequently, tears occurred on both sides and occurred more often with females and with increasing age. Other cadaver studies have noted intratendinous tears to be more frequent (7.2%) than bursal-sided (2.4%) or articular-sided tears (3.6%). However, clinically, articular-sided tears are found to be 2 to 3 times more common than bursal-sided tears and among a population of young athletes, articular-sided tears constituted 91% of all partial-thickness tears. Rotator cuff tears may be more common in men between the ages of 50–60, though between 70 and 80 there is minimal difference across genders.In terms of the size of tears, a study compared the ages of patient to the size of tears. It was emphasized the older you are, the more massive of a tear you will have. It was found that mean age increased with larger tear sizes (small tears 59 years, medium tears 62 years, large tears 64 years, and massive tears 66 years).
(5)
Associated radiological findings include a vacuum phenomenon (in the nucleus pulposis of the adjacent intervertebral disc), reduction of disc height with corresponding loss of the disc space, marginal sclerosis of the adjacent vertebral bodies, osteophyte formation and apophyseal joint instability. With a retrolisthesis there is always a less than ideal positioning of spinal segments. There is also always a reduced anterior to posterior dimension of the spinal canal compared to the way it is supposed to be. The greater the posterior displacement, the more significant it is for producing a dysfunctional spinal cord or even a cauda equina syndrome. Joint stability
Joint stability is easily evaluated by the use of flexion and extension lateral x-ray views of the spine. A summary of part of the DRE tables (6) give a guide as to the implications of the joint instability. If either translation or angular change is determined from flexion to extension to the degree shown in the table below, then Category IV instability is present. See also Joint stability.Translation is a gliding motion where one bone of a joint glides over its neighbour. Management
References

6. Hadley, Lee A. (MD), (1973) “Anatomicoroentgenographic Studies of the Spine”. 390.7. Cocchiarella L., Andersson, G. “American Medical Association Guides to the Evaluation of Permanent Impairment”, 5th  edition, Tables 15- 3, 15-4, 15-5.8. Giles, L.G.F. ; Muller R.; and Winter G.J. (2006) “Lumbosacral disc bulge or protrusion suggested by lateral lumbosacral plain x-ray film – preliminary results.” Journal of Bone and Joint Surgery. British Volume, Vol 88-B, Issue SUPP_III, 450.