The shoulder is a highly mobile ball-and-socket joint, stabilized and controlled by the rotator cuff, a group of four muscles and their tendons. This structure allows the arm to lift, rotate, and perform countless daily activities. When a medical imaging report mentions “bursal-sided fraying of the supraspinatus,” it describes specific damage to one of the rotator cuff’s most frequently injured tendons. Understanding the anatomy and the nature of the injury can provide clarity.
Anatomical Foundation: The Supraspinatus and Bursa
The supraspinatus tendon is part of the rotator cuff, originating from the top of the shoulder blade (scapula) and attaching to the upper part of the arm bone (humerus). Its primary function is to initiate lifting the arm away from the body (abduction) and assist in stabilizing the humeral head within the shoulder socket. The tendon is situated in a tight space beneath a bony overhang called the acromion.
To prevent friction between this moving tendon and the rigid bone above it, the body employs a protective layer called the subacromial bursa. The bursa is a thin, fluid-filled sac that acts as a natural cushion and lubricating layer, facilitating smooth, gliding motion as the arm moves.
The supraspinatus tendon has two distinct surfaces: the articular side, which faces the shoulder joint capsule, and the bursal side, which faces outward toward the subacromial bursa and the acromion. A healthy tendon is strong and intact across its entire thickness, allowing for powerful and pain-free movement.
Defining Bursal-Sided Fraying
Bursal-sided fraying describes a condition where the tendon fibers on the outer surface have begun to sustain damage. “Fraying” refers to microtears, thinning, or degenerative changes in the collagen fibers. This damage is typically classified as a partial-thickness rotator cuff tear because the tendon is damaged but not completely torn through from one surface to the other.
The “bursal-sided” designation is clinically important because it indicates the location of the injury, distinguishing it from an articular-sided tear, which occurs on the inner surface. Bursal-sided damage is often a result of external compression or friction against the bony arch above the tendon. Clinicians use classification systems to grade the severity of this partial tear based on the depth of the fraying, such as a grade III tear indicating damage extending over half of the tendon’s thickness.
This type of injury is considered a form of tendinopathy, which involves the breakdown of collagen and chronic irritation within the tendon structure. If the fraying is significant, it can lead to a fluid-filled defect visible on imaging, representing the beginning of a tear that has not yet progressed to a complete rupture. This damage can compromise the tendon’s integrity and mechanical function.
Common Causes and Associated Symptoms
The most frequent cause of bursal-sided fraying is chronic mechanical impingement, where the supraspinatus tendon is repeatedly pinched between the humeral head and the acromion bone. This repetitive compression, often exacerbated by a specific anatomical variation like a hooked acromion shape, leads to frictional wear on the tendon’s outer surface.
Repetitive overhead activities, common in certain sports like swimming and baseball or in occupations requiring frequent arm elevation, are significant extrinsic factors that contribute to this wear. Intrinsic factors, such as age-related degeneration, also play a role, as the tendon’s tissue weakens and becomes less resilient over time, making it more vulnerable to injury.
Poor posture or issues with the movement of the shoulder blade, known as scapular dyskinesia, can further narrow the subacromial space and increase the risk of impingement. The clinical presentation often involves pain along the outer aspect of the shoulder that may radiate down the arm. Patients commonly report pain when performing activities that involve lifting the arm out to the side, particularly between 60 and 120 degrees of abduction, a phenomenon known as the “painful arc.” Night pain is another frequent symptom, which can be severe enough to disrupt sleep, especially when lying on the affected shoulder. Weakness, difficulty with overhead tasks, or a catching sensation may also be present due to the compromised integrity of the tendon.
Management and Treatment Pathways
The initial treatment approach for bursal-sided fraying is non-surgical, focusing on conservative management to alleviate pain and restore function. Physical therapy is a primary modality, centered on strengthening the surrounding rotator cuff muscles and the muscles that stabilize the shoulder blade to improve shoulder mechanics. Activity modification is also recommended, involving adjusting movements to temporarily avoid positions or actions that aggravate the tendon.
Non-steroidal anti-inflammatory drugs (NSAIDs) can be used to manage pain and reduce any associated inflammation in the bursa itself. For persistent pain and inflammation, a corticosteroid injection may be administered directly into the subacromial space to reduce irritation of the bursa. An adequate trial of non-operative treatment typically lasts for three to six months, with most partial tears improving within this timeframe.
Surgical intervention is generally reserved for cases where conservative treatment fails to relieve symptoms or if the partial tear is high-grade (involving more than 50 percent of the tendon thickness). Surgery is often performed arthroscopically. Procedures may involve debridement to smooth the frayed edges of the tear and subacromial decompression to remove bone spurs causing the impingement. For larger, symptomatic tears, the surgeon may perform a repair to reattach the damaged tendon fibers to the bone.