Can a Fall on an Outstretched Arm Cause Rotator Cuff Tendon Injuries?
Yes, a fall onto an outstretched right arm can absolutely cause acute tears of the supraspinatus, infraspinatus, and subscapularis tendons, and this mechanism is well-documented in the literature as a legitimate cause of traumatic rotator cuff injury.
Mechanism of Injury
A simple fall represents the most common cause of traumatic rotator cuff tears, accounting for 725 cases in a comprehensive literature review of 4,061 traumatic rotator cuff injuries 1. The biomechanical explanation involves sudden eccentric loading—the tendon-muscle unit is forcefully stretched while simultaneously contracting as the person attempts to cushion the fall. This creates local stresses within the rotator cuff that can exceed the tensile strength of tendon fibers, resulting in partial or full-thickness tears 1.
During a fall on the outstretched hand, impact forces are governed by an initial high-frequency peak followed by lower-frequency oscillations that transmit proximally through the upper extremity 2. While the shoulder experiences lower peak forces than the wrist, it undergoes considerably greater deflection and absorbs the majority of impact energy 2.
Specific Tendon Involvement
Supraspinatus
The supraspinatus tendon is most frequently affected in fall-related injuries 1. This is the primary tendon injured in traumatic rotator cuff tears.
Subscapularis
Subscapularis tears occur traumatically through hyperextension or external rotation of the abducted arm—precisely the position assumed during a fall on an outstretched hand 3. In a surgical series of 14 shoulders with isolated subscapularis tears, all but three patients sustained injury through this exact mechanism 3. These injuries commonly present with:
- Pain and weakness
- Limited passive range of motion at maximal internal and external rotation
- Weakness of internal rotation
- Tenderness over the intertubercular groove 3
Infraspinatus
While less commonly isolated, infraspinatus involvement occurs in traumatic rotator cuff injuries and significantly affects overall rotator cuff function. Any degree of infraspinatus pathology correlates with supraspinatus muscle atrophy, suggesting interconnected injury patterns 4.
Clinical Implications
This is NOT simply revealing pre-existing pathology. The outdated notion that "minor trauma" cannot cause tendon tears but only reveals pre-existing disease is contradicted by biomechanical evidence 1. Fall-related tears are not restricted to young individuals—they affect patients of any age 1.
Early Surgical Repair Considerations
Early surgical repair after acute injury is an option, particularly when performed within 3 weeks of injury, as patients repaired within this timeframe demonstrate better results than those repaired later 5. However, acute rotator cuff injuries from trauma represent only approximately 5-10% of all rotator cuff repairs, indicating they are relatively uncommon despite being mechanistically valid 5.
Diagnostic Approach
For acute shoulder pain following trauma with suspected rotator cuff tear, MRI shoulder without IV contrast is the preferred imaging modality after initial radiography 6. MRI provides high sensitivity and specificity for full-thickness tears and adequately assesses soft tissue injuries including all rotator cuff tendons 6. Ultrasound represents an alternative with similar performance for full-thickness tears (90-91% sensitivity, 93-95% specificity) but is more operator-dependent 6.
Common Pitfall
Do not dismiss a patient's report of acute shoulder dysfunction after a fall as merely unmasking degenerative disease. The biomechanical forces during fall protection are sufficient to cause acute tendon failure in previously intact tendons 1.