Shoulder pain is a symptom that can exhaust patients, deprive them of sleep, and cut them off from their daily lives. At the practice, one of the most frequent diagnoses that I am called upon to make is Shoulder Tendinitis (often accompanied by Bursitis). Although many consider tendinitis as a “simple inflammation” that will pass with a little rest, the reality of human biomechanics is far more complex.
As an Orthopaedic Surgeon, my approach to pain is strictly research-based. I am not satisfied with superficial diagnoses. I am sceptical by nature when I hear the term “simple tendinitis” because behind any inflammation, there is always a deeper mechanical or anatomical cause hidden. I double-check every imaging examination, every clinical finding, and every symptom, because only by understanding why a tendon becomes inflamed can we offer a definitive, documented, and permanent treatment. In this exhaustive and fully analytical guide, we will go in-depth into what exactly it means to suffer from tendinitis and bursitis of the shoulder. We will analyse the complex anatomy of the area, the mechanisms that cause the wear, the warning signs, our diagnostic approach, and, of course, all the modern conservative and minimally invasive surgical solutions.
What is Shoulder Tendinitis and Bursitis?
To understand the condition, we must distinguish the tissues involved:
- The Tendon: It is a hard, inelastic, fibrous tissue (like an extremely durable rope) that connects muscles to bones. When a muscle contracts, it pulls the tendon, and the tendon in turn moves the bone. Tendinitis is a condition in which this “rope” undergoes micro-injuries (fraying), becomes irritated, and develops acute or chronic inflammation. In the shoulder, this usually concerns the tendons of the rotator cuff (rotator cuff tendinitis) or the tendon of the biceps muscle.
- The Bursa: Nature has arranged it so that tendons do not rub directly on hard bones. For this reason, between them there is a microscopic sac, the bursa, which contains minimal lubricating fluid and functions as a “shock-absorbing cushion”. When this sac is compressed and irritated, it fills with excess inflammatory fluid, swells, and hurts. This condition is called Bursitis.
In the majority of cases, these two conditions do not act in isolation but coexist, creating a powerful cycle of pain and stiffness.
The Biomechanics and Anatomy of the Shoulder: The Impingement “Tunnel”
To understand why tendinitis develops, it is of vital importance to take a look at how the shoulder is constructed. The main joint of the shoulder (glenohumeral) is kept stable and mobile by a group of four muscles and their tendons, called the Rotator Cuff. These muscles (supraspinatus, infraspinatus, subscapularis, teres minor) keep the head of the humerus centred in the socket of the scapula. An additional important tendon, that of the Long Biceps, passes right in front.
The problem starts from the architecture of the skeleton itself.
Above the tendons of the rotator cuff (especially of the supraspinatus), there is a bony protrusion of the scapula called the Acromion. This acromion functions as the “ceiling” or the “roof” of the shoulder. The space between this roof and the tendons is called the Subacromial Space. Inside this narrow tunnel reside the tendons and their protective bursa.
When you lift your arm above shoulder level (e.g., to swim, play tennis, or reach for an object on a high shelf), this space narrows dramatically. This recess traps, compresses, and “pinches” the tendons and the bursa onto the bone. This biomechanical phenomenon is called Impingement Syndrome. The repetitive movement causes continuous wear, resulting in the development of tendinitis and subacromial bursitis.
