MSK SHOULDER
Shoulder pain is one of the most common musculoskeletal complaints in clinical practice, and it often causes major functional limitation in work, sleep, and daily activity. In your uploaded teaching material, it is highlighted as a very common presentation with a high lifetime prevalence, and the slides also emphasize that although many patients improve with activity modification, physiotherapy, and medication, a structured evaluation is essential to identify the pain generator accurately and choose the right treatment pathway.
This webpage draft is designed for pain physicians, MSK ultrasound learners, and clinicians who want a practical, clinic-ready framework—starting from anatomy and moving to ultrasound scan protocol, examination methods, and pathology-based interpretation.
1) Functional Anatomy of the Shoulder
The “shoulder” is not a single joint. It is a functional complex made of multiple articulations and soft tissues that work together:
Core joints of the shoulder complex
- Glenohumeral (GH) joint – the main ball-and-socket joint
- Acromioclavicular (AC) joint – between acromion and distal clavicle
- Sternoclavicular (SC) joint – clavicle to sternum (important for full shoulder motion)
- Scapulothoracic articulation – not a true synovial joint, but essential for motion and rhythm
Major static stabilizers
- Labrum (deepens glenoid)
- Glenohumeral ligaments (superior, middle, inferior)
- Coracohumeral ligament (important in adhesive capsulitis)
- Joint capsule
- AC and coracoclavicular ligaments
Major dynamic stabilizers
- Rotator cuff
- Supraspinatus
- Infraspinatus
- Teres minor
- Subscapularis
- Deltoid
- Long head of biceps tendon (LHBT)
- Scapular stabilizers (serratus anterior, trapezius, rhomboids, etc.)
Your evaluation PPT appropriately starts with basic anatomy (anterior view, posterior view, rotator cuff muscles) before moving into pathology and examination—a good teaching sequence for clinical shoulder assessment.
2) Clinical Relevance of Shoulder Anatomy in Pain Medicine
A shoulder pain diagnosis becomes easier when you map pain location to likely structures:
- Lateral shoulder pain → rotator cuff / SASD bursa (especially supraspinatus-related)
- Anterior shoulder pain → LHBT, rotator interval, subscapularis, anterior capsule
- Superior shoulder pain → AC joint
- Deep joint pain / stiffness → GH joint pathology, adhesive capsulitis
- Posterior shoulder pain → infraspinatus, posterior cuff, labrum, referred cervical pain
- Scapular pain → myofascial pain, cervical radiculopathy, suprascapular nerve involvement
Your pathology PPT also classifies shoulder pain into intrinsic (glenohumeral and extra-glenohumeral), extrinsic, and traumatic causes, which is the right first sorting step in any shoulder workup.
3) Sonoanatomy of the Shoulder (USG Basics)
Ultrasound is ideal for shoulder pain because many common pain generators are superficial, dynamic, and injectable. It is especially useful for:
- Rotator cuff tendons
- Subacromial-subdeltoid (SASD) bursa
- Long head of biceps tendon
- AC joint
- Dynamic impingement
- Rotator interval changes (adhesive capsulitis clues)
Transducer and machine setup
- High-frequency linear probe (10–18 MHz)
- Start with:
- Depth: 2–4 cm (adjust to body habitus)
- Focus at target level
- High gain but avoid overcalling anisotropy as pathology
- Use color/power Doppler selectively:
- Useful in rotator interval vascularity (adhesive capsulitis suspicion)
- Tendinopathy hyperemia
- Avoiding vascular injury during interventions
Key sonographic principles
- Anisotropy is common in tendons (especially supraspinatus, biceps): always angle-correct before diagnosing tendinopathy/tear.
- Compare with the contralateral side when needed.
- Use dynamic scanning whenever possible (abduction, external rotation).
4) Ultrasound Scan Protocol for Shoulder Pain (Practical, Step-by-Step)
This is a practical protocol you can use in clinic. I recommend scanning in a standard sequence every time to avoid missing pathology.
A. Patient positioning and sequence overview
A reproducible sequence:
- Biceps tendon (anterior)
- Subscapularis tendon (anterior)
- Rotator interval (CHL / SGHL region)
- Supraspinatus tendon + SASD bursa (anterolateral)
- Dynamic impingement scan
- Infraspinatus / teres minor (posterior)
- Posterior GH joint / labrum region
- Teres Minor
- AC joint (superior)
- Optional: SC joint, suprascapular notch/spinoglenoid region if neuropathy/cyst suspected
B. Anterior shoulder: Long head of biceps tendon (LHBT)
Position
- Patient seated
- Elbow flexed ~90°
- Forearm supinated
- Arm resting comfortably
Scan
- Short-axis view over bicipital groove first
- Then rotate for long-axis view
Your uploaded pathology slides explicitly mention short- and long-axis views for biceps evaluation and describe common LHBT problems such as tendinopathy, split tear, subluxation, and rupture.
What to look for
- Tendon centered in groove?
- Effusion around tendon sheath
- Tendon thickening, hypoechogenicity, fibrillar disruption
- Subluxation/dislocation (often with subscapularis pathology)
- Complete rupture (“empty groove” / retracted tendon clinically + sonographic confirmation)
Interventional pearl
Your slides correctly caution to avoid the ascending branch of the anterior circumflex humeral artery while choosing needle trajectory during bicipital interventions.
C. Subscapularis tendon (anterior)
Position
- Arm externally rotated (“open” the lesser tuberosity insertion)
Scan
- Start in short axis over the lesser tuberosity
- Sweep medially/laterally
- Rotate for long-axis tendon assessment
What to assess
- Tendinosis
- Partial/full-thickness tear
- Calcific deposits
- Dynamic relation with LHBT (subluxation risk if pulley/subscapularis injury)
D. Rotator interval (critical for adhesive capsulitis)
This is one of the most clinically valuable scans in a stiff shoulder.
Structures in the rotator interval region
- LHBT
- Coracohumeral ligament (CHL)
- Superior glenohumeral ligament (SGHL)
- Rotator interval soft tissue
Your PPT includes important adhesive capsulitis sonoanatomy points:
- CHL thickening (normal thin vs thickened in AC)
- Increased rotator interval soft tissue
- Rotator interval vascularity on Doppler
- Dynamic restriction of external rotation being more specific than abduction restriction. shoulder pathologies Basics1 shoulder pathologies Basics1
What to look for in frozen shoulder (US clues)
- Thickened CHL
- Rotator interval soft tissue fullness
- Doppler signal in rotator interval
- Restricted dynamic external rotation
Your slide content cites a CHL threshold pattern (normal <0.7 mm vs thicker in adhesive capsulitis) and reports strong diagnostic performance for increased rotator interval soft tissue and external rotation restriction. shoulder pathologies
E. Supraspinatus tendon and SASD bursa (anterolateral / lateral)
This is the most common region scanned in painful shoulder and often the main pain generator.
Position options
- Modified Crass / Crass position (if tolerated)
- Hand on back pocket (gentler option)
- Neutral with partial extension if severe pain
Scan
- Evaluate supraspinatus tendon in long and short axis
- Assess SASD bursa superficial to cuff
- Look at cortical irregularity of greater tuberosity
Pathology clues
- Tendinopathy: tendon thickening, heterogeneity, loss of fibrillar pattern
- Partial tear: focal defect (bursal/articular/intrasubstance)
- Full-thickness tear: tendon discontinuity, fluid-filled gap, cartilage interface sign (when visible)
- Bursitis: bursal distension, fluid, synovial thickening, pain with probe pressure
Your pathology slides highlight SASD bursitis / impingement syndrome as a common and commonly injected structure and describe the painful abduction arc and impingement mechanics (between greater tubercle and coracoacromial arch).
F. Dynamic impingement scan
Dynamic ultrasound is where shoulder US becomes truly superior to static imaging for some problems.
How to perform
- Keep probe over supraspinatus/SASD region under acromion
- Ask patient to slowly abduct the arm
- Watch tendon-bursa passage beneath acromion
What to observe
- Smooth gliding vs bunching/impingement
- Pain reproduction
- Bursal “pinching”
- Incomplete tendon passage (especially in stiffness / adhesive capsulitis)
Your slides show dynamic examples and specifically note incomplete passage of supraspinatus/SASD under acromion in adhesive capsulitis during abduction.
G. AC joint scan (superior shoulder pain)
The AC joint is small but clinically important.
Your PPT gives a very practical reminder that although the AC joint is superficial and palpable, it is often narrowed or shielded by osteophytes, and ultrasound is very helpful because SASD bursa and supraspinatus lie directly beneath it.
Scan technique
- Probe in coronal/oblique plane over distal clavicle-acromion
- Identify joint gap and cortical margins
Assess for
- Joint narrowing
- Osteophytes
- Effusion
- Synovial hypertrophy
- Local tenderness with sonopalpation
H. Posterior shoulder scan: Infraspinatus / Teres minor / Posterior GH joint
Position
- Hand on opposite shoulder or neutral relaxed
Scan
- Posterior cuff tendons
- Posterior GH recess
- Posterior labral region (limited but sometimes helpful)
- Spinoglenoid region if suprascapular neuropathy/paralabral cyst suspected
Use cases
- Posterior cuff tears/tendinopathy
- GH joint effusion
- Paralabral cyst suspicion
- Dynamic painful posterior snapping (selected cases)
- Posterior cysts → suprascapular nerve compression
- Inferior cysts → axillary nerve compression (quadrilateral space syndrome pattern).
5) Clinical Evaluation of Shoulder Pain (History + Examination)
Your shoulder evaluation PPT provides a very good clinic-friendly structure: inspection, palpation, ROM, neurological exam, and special tests. EVALUATION-OF-SHOULDER-PAIN sus…
A. History (what matters most)
- Duration
- Pain severity and quality (nociceptive / neuropathic)
- Aggravating and relieving factors
- Radiation
- Diurnal variation
- Occupation
- Medical history (especially diabetes, thyroid, inflammatory disease)
- Traumatic vs non-traumatic onset EVALUATION-OF-SHOULDER-PAIN sus…
Practical history clues
- Night pain + painful arc → cuff / bursitis
- Progressive stiffness (both active + passive) → adhesive capsulitis
- Overhead athlete + clicking → labral pathology
- Pain on cross-body adduction / top of shoulder pain → AC joint
- Neck pain + arm radiation / paresthesia → cervical source
- Severe sudden weakness after trauma → acute cuff tear (red flag)
B. Red flags in shoulder pain (don’t miss)
- Tumor (e.g., apical lung/Pancoast region concern)
- Acute rotator cuff tear
- Unreduced dislocation
- Infection
- Unexplained motor/sensory deficit
- Pulmonary/vascular compromise
- Myocardial ischemia/infarction EVALUATION-OF-SHOULDER-PAIN sus…
If present, these require urgent escalation—not routine injection workup.
C. Examination framework
1) Inspection
Look anteriorly and posteriorly:
- Symmetry
- Clavicle deformity
- AC joint prominence
- Deltoid wasting
- Scapular winging (long thoracic nerve / serratus anterior issue)
2) Palpation
Palpate systematically:
- SC joint
- Clavicle
- AC joint
- Bicipital groove
- Greater tuberosity / cuff insertion
- Posterior joint line
- Cervical facets and trapezius trigger points
3) Range of motion (active + passive)
- Flexion
- Extension
- Abduction
- Adduction (including horizontal adduction)
- Internal rotation
- External rotation
- Apley scratch test (global functional screen) EVALUATION-OF-SHOULDER-PAIN sus…
Interpretation tip
- Painful but preserved passive ROM → cuff/bursa more likely
- Painful + restricted passive ROM → adhesive capsulitis / GH arthritis
4) Neurological exam
Include:
- Sensory exam
- Motor power
- Reflexes (biceps C5, brachioradialis C6, triceps C7)
This is essential to avoid missing cervical radiculopathy or neuropathy.
D. Special tests (high-yield)
Impingement tests
- Neer’s test
- Hawkins-Kennedy test
Useful when suspecting SASD bursitis / cuff impingement pattern. (Interpret with ultrasound correlation; avoid overdiagnosis from a single positive test.)
Rotator cuff tests
- Drop arm test (supraspinatus/infraspinatus tear suspicion)
- External Rotation Lag Sign (infraspinatus / posterosuperior cuff tear)
These are explicitly described in your slides.
Instability tests
- Apprehension
- Relocation
- Anterior release
Important in younger patients, trauma history, recurrent dislocation, or labral injury suspicion.
AC joint / Labral screening
- AC joint tenderness
- O’Brien (Active Compression) test
Your slide notes O’Brien can indicate SLAP or AC pathology depending on symptom location and response.
Biceps tendon tests
- Speed test
- Yergason test
These are clearly summarized in your PPT and pair well with bicipital groove ultrasound.
6) Common Shoulder Pathologies (Clinical + USG-Oriented View)
1. Subacromial-Subdeltoid (SASD) Bursitis / Impingement Syndrome
A very common pain generator and commonly injected target in pain practice. Your slides emphasize it as one of the most commonly injected structures.
Clinical clues
- Painful arc (classically 60–120°)
- Pain with overhead activity
- Night pain
- Positive Neer/Hawkins
USG clues
- Bursal fluid or thickening
- Hyperemia (sometimes)
- Dynamic impingement during abduction
- Coexisting cuff tendinopathy
2. Rotator Cuff Tendinopathy / Tear (especially supraspinatus)
Clinical clues
- Lateral shoulder pain
- Pain on abduction
- Weakness (empty can / drop arm depending severity)
USG clues
- Tendon thickening and heterogeneity (tendinopathy)
- Partial tear defects
- Full-thickness discontinuity
- Greater tuberosity cortical irregularity
3. Long Head of Biceps Tendinopathy / Tear / Subluxation
Note the LHBT as a commonly injured structure with tendinopathy, splits, SLAP relation, rupture, and subluxation.
Clinical clues
- Anterior shoulder pain
- Pain in bicipital groove
- Positive Speed/Yergason
- Possible “Popeye” deformity in rupture
USG clues
- Sheath fluid
- Tendon thickening / split
- Groove instability
- Empty groove (rupture)
4. AC Joint Arthropathy
Small joint, frequent pain generator, especially in older patients and overhead activity.
Clinical clues
- Top-of-shoulder localized pain
- Pain on cross-body adduction
- AC tenderness
- O’Brien may reproduce AC pain
USG clues
- Osteophytes
- Narrowing
- Effusion
- Synovitis
- Probe tenderness correlation
5. Adhesive Capsulitis (Frozen Shoulder)
They also note the higher prevalence in women (40–70 years) and association with diabetes.
Clinical hallmarks
- Progressive pain and stiffness
- Restriction of both active and passive ROM
- External rotation restriction is especially important
USG clues (supportive, not isolated diagnosis)
- CHL thickening
- Rotator interval soft tissue thickening
- Doppler vascularity in rotator interval
- Dynamic restriction of external rotation (very useful)
6. Glenohumeral Osteoarthritis
Often under-recognized compared with cuff disease.
Clinical clues
- Deep joint pain
- Crepitus
- Global stiffness
- Older age / degenerative pattern
USG clues
- Effusion
- Osteophytes (limited depending window)
- Cartilage irregularity (best in optimized positioning)
- Posterior recess fluid/synovitis
7. Labral Pathology and Paralabral Cysts
Clinical clues
- Clicking/catching
- Instability symptoms
- Pain with overhead activity
- Positive apprehension / O’Brien depending lesion pattern
Ultrasound role
- Limited direct labral visualization
- Helpful for:
- Paralabral cyst detection
- Dynamic assessment
- Guided diagnostic injections
- Screening associated cuff/biceps pathology
7) Diagnostic Approach for a Pain Clinic (Simple Practical Algorithm)
Step 1: Rule out red flags
If yes → urgent referral / advanced workup.
Step 2: Decide pain source bucket
- Traumatic
- Non-traumatic intrinsic
- Extrinsic / referred
(Your slides use this exact framework.) EVALUATION-OF-SHOULDER-PAIN sus…
Step 3: Examine active vs passive ROM
- Passive preserved → cuff/bursa/biceps likely
- Passive restricted → frozen shoulder / GH OA likely
Step 4: Perform targeted special tests
Use test clusters, not isolated tests.
Step 5: Ultrasound mapping
Scan in a fixed sequence:
biceps → subscapularis → rotator interval → supraspinatus/SASD → dynamic impingement → AC → posterior cuff/GH
Step 6: Correlate and confirm
Use:
- Sonopalpation
- Dynamic pain reproduction
- Diagnostic injection (when needed)
8) Why This Matters in Interventional Pain Practice
Shoulder pain treatment outcomes improve when the intervention is based on precise anatomical diagnosis, not just a generic “shoulder injection.” Your uploaded material also highlights the role of:
- Diagnostic interventions
- GH injections
- Nerve targets (suprascapular, axillary, lateral pectoral) in advanced pain practice / RFA context.
