A calcium deposit accumulates in one of the tendons of the shoulder. The cause is unknown and not related to injury, diet or osteoporosis. The patient most commonly affected is a female 40-50 years of age, but other age groups and males are regularly affected.
The calcium deposit is a paste-like material in the tendon and not a hard object like one would expect.
The calcium deposit accumulates in the substance of the tendon and one of the reasons for the pain could be that the fibres of the tendon are pushed apart by the bulk of the calcium. (Fig.1 and 2)
Fig. 1: Calcium deposit bulging on the surface of the rotator cuff tendon
Fig. 2: Section of the shoulder, demonstrating a calcium deposit in the tendon
Fig. 3: Calcium deposit seen inside the tendon,
protruding into the subacromial space – there
is intense redness indicating the inflammation surrounding the calcium
Fig. 4: The paste-like Calcium escaping from
The calcium also protrudes above the surface causing mechanical impingement against the under surface of the acromion when raising the arm (fig. 2, 3). Another reason for pain is that the calcium is a foreign substance and when it escapes from the tendon into the subacromial space it is recognized as a foreign material eliciting an intense inflammatory response with acute pain (Fig. 4).
The pain can be constant and nagging and is felt in the shoulder and outside of the upper arm, at times down the arm to the hand- aggravated by elevation of the arm. Night pain is often a feature and pain is intensified when raising the arm. In some instances the pain as well as tingling of the arm and fingers is experienced and may lead the treating physician think of the diagnosis of a nerve lesion of the neck.
Some patients experience attacks of excruciating pain, which then abate to a lower level after a few days.
Fig. 5: In this lady with a massive calcific deposit in the
tendon the bulge of the calcium is apparent from the outside.
An attack of pain with an extreme intensity lasting for a few days occurs at times. During this attack the pain is constant and no movements of the arm are possible. The pain is due to the body absorbing the calcium and the process of absorption is accompanied by intense inflammation causing the pain.
After a few days the pain improves when the calcium has been absorbed- an X-ray taken at this stage will show that a previously evident deposit (as seen in fig. 6) would now have disappeared
The cause of calcific tendinitis is unknown: it is not due to a faulty diet, not due to injury or overuse and not related to osteoarthritis or osteoarthritis.