Internal Rotation, also known asmedial rotation, of the Glenohumeral Joint is defined as axial rotation of the Humerus around its longitudinal axis (SOURCE-4). In layman’s terms this describes turning the upper arm towards (or in front) of the body, depending on the arms position. About 70-85º of Internal Rotation should be available to the Glenohumeral Joint , this increases to 90º when the arm is in 90º of GH Joint - Abduction (SOURCE-4+6). As with all motions of The Shoulder Girdle , Internal Rotation is accompanied by accessory movements at the Scapulothoracic Joint and the Sternoclavicular Joint .
together these bones form the following relevant joints:
Muscle -prime movers
Deltoid (anterior fibres)
Glenohumeral Joint Capsule (posterior fibres)
Inferior Glenohumeral Ligament (posterior portion)
During Internal Rotation of the Glenohumeral Joint , the convex Head of Humerus rolls anteriorly and glides posteriorly on the fixed Glenoid Cavity about the long axis of the Humerus (SOURCE-4+6). These arthrokinematics maximise joint congruency despite the considerable size disparity between the Glenoid Fossa and much larger Humeral Head. With no arm elevation, approximately 70-85º of Internal Rotation is available to the Glenohumeral Joint (SOURCE-4+6). This Range of Motion increases to ~90º when the arm is also in 90º GH Joint - Abduction (SOURCE-4+6).
Consistent muscular contribution to Internal Rotation is afforded by the Pectoralis Major , Anterior Deltoid , Latissimus Dorsi and Teres Major despite the extent of arm elevation (SOURCE-4+12+13). Conversely, the Subscapularis is the predominant Internal Rotator with the arm by the side of the body, it may be surpased with increasing GH Joint - Abduction (SOURCE-12+13).
In terms of Rotator Cuff activity during Internal Rotation, the Subscapularis is considerably more active than the other muscles, with the Infraspinatus displaying some activity while the Supraspinatus displays very little (SOURCE-2). The Infraspinatus and Subscapularis co-contract to stabilise the Head of Humerus on the Glenoid during movement. This appears to be an anticipatory role as the Rotator Cuff displays activity significantly earlier than the larger, more superficial internal rotators (SOURCE-2).
The muscle mass of the shoulders Internal Rotators is far greater than that of the External Rotators, producing ~1.75 times more isometric Torque (SOURCE-4).
While GH joint Internal Rotation is often described as the Humerus rotating about a fixed Scapula , it can also occur with a fixed Humerus and rotating Scapula . This occurs as the concave Glenoid Fossarolls and slidesin same direction (SOURCE-4).
The Posterior Glenohumeral Joint Capsule , Inferior Glenohumeral Ligament (posterior portion), Teres Minor and Infraspinatus are all pulled taut approaching end-range Internal Rotation and restrict the necessary posterior glide of the Humerus when restricted (SOURCE-6). Chronic stress may lead to fibrotic adaptation of the Posterior Capsule and the development ofGlenohumeral Internal Rotation Deficit (GIRD). GIRD is characterised by a loss of Internal Rotation on the dominant side comapred to the non-dominant side. This Internal Rotation loss often corresponds with a gain in GH Joint - External Rotation (SOURCE-13). In the presence of a restricted Posterior Glenohumeral Joint Capsule , increased External Rotation may lead toInternal Impingementof the Shoulder and the associated cascade of Rotator Cuff pathology ( Tears or Tendinopathy ) or Glenoid Labrum Tear s, in particular SLAP Lesion s.
During Scaption ( GH Joint - Abduction in the Scapula plane), increased Internal Rotation of the Humerus may coincide with or exacerbate Anterior Scapular Tilting and Scapular Winging (SOURCE-5). Chronically, this dysfunctional movement pattern increase the likelihood of conditions such as Subacromial Impingement (SOURCE-5).
Although rare, the second most common form of Glenohumeral Dislocation is the Posterior Dislocation, accounting for ~2-5% of all shoulder dislocations (SOURCE-14+15). These dislocations are often attributed to high velocity impacts (such as motor vehicle accidents), strong muscle contractions (such as a Seizure) or direct trauma to the anterior Humeral Head (SOURCE-14+15). The mechanism behind posterior dislocations typically involves forceful GH Joint - Adduction with GH Joint - Internal Rotation and there is associations with Reverse Hill-Sachs Lesions (SOURCE-14+15). Posterior Dislocations are often (~50-79%) misdiagnosed at initial presentation (SOURCE-14+15).
Internal Rotation of the Glenohumeral Joint may be limited by Pain , mechanical block or soft-tissue restriction. The chronic loss of Internal Rotation, as described inGlenohumeral Internal Rotation Deficit (GIRD), is a key pathomechanical precursor in overhead athletes. This restriction shifts the shoulders arch of motion which serves as a predisposing factor to many pathologies of The Shoulder Girdle .
Posterior Glenohumeral Instability - while considerably more rare than its anterior counterpart, Posterior Glenohumeral Dislocations often involves a combination of forceful GH Joint - Adduction and GH Joint - Internal Rotation (SOURCE-14+15). This mechanism rarely occurs in isolation and often leads to concomitant injury such as Reverse Hill-Sachs Lesion s, Reverse Bankart Lesion s, Subscapularis Avulsion Fractures or a Fracture of the Posterior Glenoid Rim (SOURCE-17).
Adhesive Capsulitis - from the freezing stage and beyond Internal Rotation may become restricted in response to Contracture formation within the Glenohumeral Joint Capsule and progressive loss of the Axillary Pouch (SOURCE-7+8)
Internal/ Posterior Impingement - a loss of Internal Rotation, as described inGIRD, is considered the initial step in the pathophysiologic cascade that leads to Internal Impingement (SOURCE-18). In certain populations such as the overhead throwing athlete, this leads to fibrotic adaptations in the Posterior Band of the Inferior Glenohumeral Ligament and the Posteroinferior Glenohumeral Joint Capsule and a consequent posterosuperior migration of the Head of Humerus during overhead motions such as throwing (SOURCE-18+19). This migration forms the basis of excessive strain as the Greater Tuberosity and articular surface of the Rotator Cuff impinge against the Posterosuperior Glenoid Labrum when The Shoulder Girdle is in an Apprehension Test -like position (SOURCE-19). This mechanism most often compromises the Posterosuperior Glenoid Labrum and Rotator Cuff (typically at the myotendinous junction of the Anterior Infraspinatus ) but has also been described to implicate the Greater Tuberosity, Inferior Glenohumeral Ligament and Posterosuperior Glenoid Cavity (SOURCE-18).
Scapular Dyskinesis - Posterior Glenohumeral Joint Capsule restriction forms an avenue by which Internal Rotation restriction may foster abnormal Scapula mechanics. This often results in a forward posture of the Scapula with excessive Anterior Scapular Tilting (SOURCE-1+20). This relation is emphasised by the fact that up to 100% of patients with Internal Impingement have Dyskinesis (SOURCE-19).
Humeral Retroversion - increases the functional GH Joint - External Rotation range in sacrifice of GH Joint - Internal Rotation which directly alters the length-tension relationship of the Rotator Cuff (SOURCE-3). A low retroversion angle may be considered a predisposing factor for Internal Impingement (SOURCE-18).
The following observable signs may be related to Internal Rotation of the Glenohumeral Joint :
Resting Arm Position - the relative tone of the shoulders rotators can be suggested by the resting position of the Cubital Fossa, The Hand and Thumb , where they should be neutrally rotated. If they are more medially facing, this suggests an increased tone in the Internal Rotators
Muscle Atrophy - of the Subscapularis , Latissimus Dorsi , Pectoralis Major or Teres Major
Abrasion Sign- crepitis throughout rotation from a position of 90º GH Joint - Abduction indicates abrasion of a torn Tendon margins against the Coracoaromial Arch (SOURCE-13)
Scapular Dyskinesis - Posterior Glenohumeral Joint Capsule restriction often presents with an excessive forward Scapula posture (SOURCE-1+20)
Internal Rotation of the Glenohumeral Joint represents a major component of the Shoulder - Active Range of Motion and Shoulder - Passive Range of Motion assessment. With the arm by the side, approximately 75-85º of Internal Rotation should be available, this range increases to a 90º with the arm in 90º GH Joint - Abduction (SOURCE-4+6). Internal Rotation is often assessed in 90º GH Joint - Abduction as it better isolates movement to the Rotator Cuff and is typically more revealing/ provocative (SOURCE-6). To mitigate compensation during Range of Motion assessment, the patient should be positioned prone or supine (SOURCE-13).
Results should be compared to GH Joint - External Rotation as the opposing movements tends to have an inverse relationship where the gain of Range of Motion in one direction corresponds to a loss in the other (SOURCE-13). Additionally, bilateral comparisons should be made to establish theGlenohumeral Internal Rotation Deficit (GIRD). A GIRD ≥20º difference between sides or a ≥5º difference in theTotal Arc of Motionis generally considered pathological (SOURCE-13).
If passive Internal Rotation is greater than Internal Rotation the patient can peform actively, neuromusculature inhibition or weakness is implicated.
The following Shoulder - Special Tests may be relevant in the assessment of dysfunctional Internal Rotation: Subscapularis
General Strength
GIRD
Measure and compare Range of Motion
Internal/Posterior Impingement
Posterior Glenohumeral Instability
Posterior Glenohumeral Joint Capsule
Spurling’s Test - evaluates potential Radiculopathy from the Cervical Spine
The following tests may be conducted to rule in/out nerve contribution with C5 , C6 , C7 , C8 and T1 Nerve Roots relevant to Internal Rotation: Cervical - Myotomes (active resisted)
Cervical - Dermatomes - evaluates sensory region
C5 - skin over the lateral shoulder/ Deltoid towards base of Thumb
C6 - skin over lateral arm from shoulder to Thumb and index Fingers
C7 - skin over posterior arm from shoulder to middle Fingers
T1 - skin over the medial forearm from The Elbow to The Hand
Reflex - diminished reflex indicates potential lesion at corresponding Nerve Root
Upper Limb Nerve Tension Tests
The following imaging modalities may be relevant for the evaluation of Internal Rotation dysfunction:
Ultrasonography (Ultrasound)- a highly accessible imaging modaility with real-time capabilities for the evaluation of soft-tissues including the Subacromial Bursa , Rotator Cuff and their Tendon s. A major limitation of this modaility is that it is highly operator dependent. Compared to other imaging modailities, Ultrasounds are less expensive/more practical in the evaluation ofAcromiohumeral Distance, a metric that determines the Subacromial Space (SOURCE-9).
Radiography (X-Ray)- evaluates Bone pathology which could mechanically block Internal Rotation. In addition to visualisation of traumatic injuries such as Fractures to the Head of Humerus or Acromion of Scapula , X-Rays may reveal degenerative osseous changes such as Osteoarthritis , Sclerosis , Osteophytes (bone spurs) and joint space narrowing (Glenohumeral Joint or resting Acromiohumeral Distance).
Magnetic Resonance Imaging MRI- can be used to directly measure the acromiohumeral space with a reduction anticipated in impingement or measure associated metrics such as the width of the Subdeltoid Bursa which indicates impingement through the presence of Bursitis (SOURCE-10+11). MRIs are also the preferred technique for evaluating soft tissues such as the Rotator Cuff , Subacromial Bursa and associated morphologies (SOURCE-11). A “Halo-sign” around Long Head of Biceps Tendon may suggest severity as it represents Glenohumeral Joint effusion and synovial thickening may be visualised in chronic cases (SOURCE-11). For Subacromial Impingement the following view are recommended (SOURCE-11):
Proton-density and T1-weighted images in coronal plane
T2-weighed images in sagittal plane - high signal fluid within Bursa is a direct sign of Inflammation
MR-arthrography with contrast injection - capable of revealing more subtle findings like lesions of the Cartilage or Glenoid Labrum
The treatment of Internal Rotation dysfunction should be specific to the underlying cause. For rehabilitation of common underlying conditions such as Rotator Cuff pathology, Adhesive Capsulitis or Posterior Glenohumeral Instability , see their respective pages.
The following Stretching techniques may directly or indirectly improve Internal Rotation restriction:
Genie Stretch - rudimentary horizontal adduction stretch
Sleeper Stretch - greater emphasis on GH Joint - Internal Rotation
Sleeper Stretch MWM - internal rotation stretch combined with Humerus Mobilisation
Seated Thoracic Rotation with Breathing - large lateral flexion and rotation range coupled with breathing
Bent Over Lat Stretch (perpendicular variant) - accessible active stretch with large GH Joint - Flexion or Horizontal GH Joint - Adduction range
Shoulder Dislocates - mobility exercise that emphasises the greatest circumduction range possible
Split Stance Biceps Stretch - self-guided anterior shoulder stretch with large GH Joint - Extension range
Banded Capsule Rolls - split stance biceps variation that emphasises shoulder rotation
As a specific training protocol relates to the underlying cause of Internal Rotation dysfunction, the following lists Internal Rotation-based Strength exercises in rough descending order from most rudimentary:
Rotator Cuff Pendulums - oscillatory motion that afford a distracting glide to the Humeral Head
Rotator Cuff Banded Rotations - light low range isotonic rotation exercises
Isometric Chest Squeezes - isometric exercise that isolates Chest
Banded Horizontal Adduction - low load isotonic horizontal adduction exercise
Banded Unilateral Lat Activations - activate lat, posteroinferior drawer on Humerus
Chest Press Machine - rudimentary horizontal push machine
Push-Up - bodyweight isotonic horizontal push exercise
Lat Pulldown - rudimentary weighted isotonic vertical pull movement with a high range of motion
Bench Press - isotonic horizontal push exercise with capacity for high loads
Straight Arm Lat Pulldown - isotonic motion that emphasises Lats and straight arm strength
Incline DB Bench Press - unilaterally loaded Bench variation on variable incline
Dips - bodyweight isotonic push exercise with large GH Joint - Extension range
DB Pullover - moderate isotonic movement with large overhead and Thoracic - Extension range
Chest Fly - large horizontal abduction range to emphasise lengthening of the Chest
The following Mobilisation techniques may be relevant in the treatment of Internal Rotation: Joint Play
Anterior Glide on Humerus - particularly Hand Behind Back variation
Posterior Glide on Humerus - stretches Posterior Glenohumeral Joint Capsule which may restrict movement and commonly restricted in GIRD
Cervical Spine - for instances of Radiculopathy a PACVP , PAUVP or TVP may be applied to relevant Cervical segment(s) in addition to the following techniques:
Thoracic Spine - mobilisations of the upper segments may improve symptoms of shoulder dysfunction, where a rounded shoulder posture is present (SOURCE-16):
Mobilisation with Movement - as Internal Rotation is affected, mobilisations may benefit from the addition of movement:
Shoulder - MWM Techniques - Internal Rotation is a key component of many techniques, however, some may be more relevant than others to the CSIM . The following lists those movements that involve Internal Rotation and other movements they’re paired with:
Practitioner Guided
Shoulder - MWM 6 - Hand behind back
Shoulder - MWM 7 - Hand behind back
Shoulder - MWM 8 - Internal Rotation
Self-Guided
Sleeper Stretch MWM - GH Internal Rotation
Cervical Spine - in addition to NAGS or SNAGS applied to a relevant Cervical segment, the following techniques may be indicated with suspected Radiculopathy :
Thoracic Spine - mobilisations of the upper segments may improve symptoms of shoulder dysfunction, where a rounded shoulder posture is present (SOURCE-16)
Reverse NAGS - particularly useful for pain or restriction associated with movement of the Upper Thoracic region
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