Rotator Cuff Tendinopathy: Subacromial Impingement vs Internal Impingement in Throwers
In short
Shoulder impingement is not a single diagnosis. Learn the critical difference between subacromial outlet impingement and internal posterior impingement in overhead throwers.
In this guide (5 sections)
Differentiating Subacromial from Internal Impingement
Shoulder impingement is the most frequent clinical presentation in upper extremity sports medicine. However, failing to differentiate subacromial outlet impingement from posterosuperior internal impingement leads to inappropriate rehabilitation and treatment failure.
Subacromial Impingement (SAI), popularized by Charles Neer, occurs in the subacromial space beneath the coracoacromial arch, where the supraspinatus tendon and subacromial bursa are compressed against the anteroinferior acromion during forward flexion and internal rotation.
In contrast, Internal Impingement, described by Stephen Burkhart and Craig Morgan, occurs inside the glenohumeral joint cavity in overhead throwing athletes (cricket bowlers, tennis and javelin players). During the late cocking phase of throwing (extreme abduction and external rotation), the articular surface of the supraspinatus and infraspinatus tendons is pinched between the greater tuberosity and the posterosuperior glenoid labrum.
Clinical Differentiation and Examination Cluster
Accurate triage requires specific provocative physical tests and rotational range of motion measurements.
| Diagnostic Feature | Subacromial Impingement (Neer / Hawkins) | Internal Posterior Impingement (Overhead) | Biomechanical Differentiation | |
|---|---|---|---|---|
| 1. Site of Pain | Anterolateral shoulder radiating to lateral deltoid insertion | Deep, posterior shoulder joint pain at late cocking phase | Subacromial bursal vs posterior labral-tendon contact. | |
| 2. Provocative Position | Arm elevated in 60 to 120 degrees forward flexion (Painful Arc) | Arm placed in 90 degrees abduction and maximal external rotation | Outlet entrapment vs posterosuperior intra-articular contact. | |
| 3. Primary Physical Tests | Positive Neer test and Hawkins-Kennedy impingement sign | Positive Posterior Impingement Sign; positive Jobe Relocation | Different anatomic locations of soft-tissue pinching. | |
| 4. Patient Demographics | Adults over 40; manual workers; desk posture | Young overhead throwing athletes (cricket bowlers, swimmers) | Degenerative tendon decline vs repetitive throwing microtrauma. |
Glenohumeral Internal Rotation Deficit (GIRD) and Sleeper Stretch
Overhead throwers frequently develop Glenohumeral Internal Rotation Deficit (GIRD): a loss of internal rotation in the throwing shoulder compared to the non-throwing shoulder, caused by posterior capsular contracture and osseous humeral retroversion.
A loss of internal rotation greater than 18 to 20 degrees with a concomitant decline in Total Rotational Motion (TRM) shifts the humeral head anterosuperiorly, precipitating internal impingement and SLAP labral tears.
- The Sleeper Stretch for Posterior Capsule: Lie on the throwing side with shoulder and elbow flexed to 90 degrees. Use the opposite hand to gently push the forearm downward into internal rotation for 30 seconds, 3 to 5 reps.
- Rotator Cuff Isometric Analgesia: Perform isometric external and internal rotation holds at 30 degrees abduction using resistance bands: 5 sets of 45 seconds to relieve resting shoulder pain.
- Lower Trapezius and Serratus Anterior Activation: Perform prone Y-to-T raises and push-up plus drills to ensure optimal upward scapular rotation during arm elevation.
- Kinetic Chain Integration: Throwing velocity is generated primarily from the lower body and trunk; incorporate hip rotational lunges and medicine ball rotational slams into late-stage rehab.
Cricket Fast Bowler Realities in India
Fast bowlers in India endure extreme glenohumeral shear forces during front-foot delivery stride.
Physiotherapists enforce strict weekly bowling spell monitoring, mandate sleeper stretches post-match, and train posterior cuff deceleration strength.
Frequently Asked Questions
What is the Total Rotational Motion (TRM) concept in throwers?
TRM is the sum of external rotation and internal rotation measured at 90 degrees abduction. In healthy throwers, external rotation increases while internal rotation decreases, but the total rotational arc (typically ~180 degrees) should remain equal between throwing and non-throwing shoulders (within 5 degrees).
Can subacromial decompression surgery fix internal impingement?
No. Subacromial decompression (acromioplasty) shaves bone outside the joint capsule and fails to address intra-articular posterior contact, frequently worsening instability in overhead throwers. Targeted rehabilitation is the primary treatment.
How do you perform the Jobe Relocation Test for internal impingement?
With the patient supine, bring the arm into 90 degrees abduction and maximal external rotation (producing posterior pain). Apply a posterior-directed force on the anterior humeral head: if pain immediately disappears, it confirms internal impingement.
Related condition guides
Related recovery guides & articles
BookPhysio.in Editorial Team
The BookPhysio.in editorial team writes and maintains this content, checking it against reliable clinical sources. Content follows our medical review policy: general information only, and no page claims a clinical review until a named registered physiotherapist has signed it off.
Read our medical review policy