The tendon is the structure that attaches a specific muscle to a bone. Each muscle has a thin fascia sheath which comes together at the end of the muscle forming a tendon. This tendon attaches to a bone enabling the bone to move in a prescribed fashion. Tendons are tough, rope-like structures that have a covering similar to a paper wrapping around a straw. The individual structures of the tendon can be acutely injured or become chronically degenerative.
Tendinosis and tendinitis are each separate clinical situations affecting the tendons. Understanding there is some similarity between these two different clinical situations, each has very distinct characteristics. Moreover, each diagnosis is treated differently.
Tendinitis is an acute condition characterized by an inflammatory process of that structure. Generally, this particular process is caused by an acute injury, a sudden increase in utilization, or overuse of the noted structure or can be related to a repetitive strain-type scenario. A sudden increase in physical activity has been known to be causative of tendinitis.
The symptoms of tendinitis include pain made worse with movement, swelling or tenderness at the location of the afflicted structure, and there might be swelling and pain to palpation at the noted area. A limited range of motion is also a distinct possibility.
Tendinosis is a chronic condition resulting from a degeneration of the collagen within a tendon or complications secondary to healing of a specific injury. This particular finding is also known as tendinopathy, possibly a chronic tendon injury, and in rare instances described as rhenosis. A key difference is that there are generally no indicators of inflammation.
Findings on diagnostic imaging studies could include thickening or nodules within the tendon structures. Also, there would be no evidence of inflammation or swelling. The tendon becomes less elastic, thereby compromising the functionality of the muscle/joint.
Therefore, a careful clinical history must be obtained, and a detailed physical examination completed and reported so that the most accurate diagnosis can be made. The clinical history reported needs to indicate if the onset of symptomology was acute or gradual. The physical examination should show if there is or is not an indicator of inflammation such as erythema or swelling. Tenderness to palpation, noted as sharp and sudden, should be addressed in the physical examination.
To be clear, if the onset is acute, and there is tenderness to palpation at the insertion of the tendon, this would be tendinitis. The treatment would include nonsteroidal medications, augmented with a physical therapy protocol, and possibly a steroid injection.
However, if the findings are gradual onset, and there are long-term complaints not associated with a specific event, then the diagnosis would be a tendinosis. If the MRI studies report a tendinosis, generally this is not associated with an acute compensable event. In both cases, rest, ice, local compression, and elevation (RICE protocols) should be applied. However, the treatment for tendinosis may include home-based stretching exercises, and in rare cases platelet-rich plasma (PRP) injections.
In summary, a diagnosis of tendinitis represents an inflammatory process, which has an acute onset and specific physical examination findings. Tendinosis is a chronic degenerative condition secondary to repeated use/overuse or other complications. Careful identification of the actual pathology is paramount when addressing this as part of a compensable injury.