The Shoulder — From Clinic to Recovery · Interactive Surgical Atlas

01

Foundations · Anatomy

Anatomy & Biomechanics of the Rotator Cuff

Matsen et al.¹ —

The glenohumeral joint balances extreme mobility with intrinsic instability¹. The shallow glenoid fossa accommodates less than one-third of the humeral head surface area, making dynamic stabilization through the rotator cuff critical for function¹.

Clinical snapshot

Arterial supply

Suprascapular & anterior/posterior humeral circumflex arteries. Critical watershed zone located 1 cm proximal to the insertion of the supraspinatus tendon at the greater tubercle¹.

Innervation

Suprascapular N. (C5-C6): supraspinatus & infraspinatus¹.
Axillary N. (C5-C6): teres minor & deltoid¹.

Radiographic landmark

True AP (Grashey view): beam angled 35-40° toward the affected shoulder to profile the joint space cleanly without glenoid rim overlap¹.

Structural foundations

Rotator cuff musculature specifications

Muscle	Scapular origin	Humeral insertion	Primary action	Innervation
Supraspinatus	Supraspinous fossa	Superior facet, greater tubercle	Initiates abduction; centres head	Suprascapular N. (C5-C6)
Infraspinatus	Infraspinous fossa	Middle facet, greater tubercle	External rotation; posterior stability	Suprascapular N. (C5-C6)
Teres minor	Lateral scapular border	Inferior facet, greater tubercle	External rotation in elevation	Axillary N. (C5-C6)
Subscapularis	Subscapular fossa	Lesser tubercle	Internal rotation; anterior restraint	Upper/lower subscapular N. (C5-C6)

Coracohumeral & glenohumeral ligamentous complex

The coracohumeral ligament (CHL) originates from the base of the coracoid process and spans across the rotator interval, enveloping the supraspinatus tendon margin¹. It acts in conjunction with the superior glenohumeral ligament (SGHL) to form a stabilizing pulley system for the long head of the biceps tendon within the bicipital groove³.

Concavity-compression mechanism

Because the osseous socket is inherently flat, stability is maintained by pressing the convex humeral head into the concave glenoid socket bounded by the glenoid labrum¹. Dynamic co-contraction of the rotator cuff creates compressive forces preventing translation under load¹.

Clinical media

Media 01 · Ultrasound-guided injection

Plate 01 · Rotator cuff anatomy

02

Clinical pathway · Impingement

Subacromial & Internal Impingement Syndromes

Neer² Bigliani⁶ —

Mechanical compression of subacromial structures against the coracoacromial arch during overhead arm elevation². Morphological variations of the acromion directly constrain the outlet space for the supraspinatus tendon⁶.

Clinical snapshot

Radiographic view

Scapular-Y (outlet view): patient standing 45° to cassette, beam angled 10-15° caudal to profile acromial morphology (Bigliani types I-III)⁶.

Vascular consideration

Thoracoacromial artery (acromial branch) supplies the coracoacromial ligament and subacromial bursa¹.

Clinical pathway

Pathophysiology & classification

Subacromial impingement involves dynamic or mechanical compression of the subacromial bursa and supraspinatus tendon beneath the coracoacromial arch². Bigliani classified acromial morphology into three types: Type I (flat, 17%), Type II (curved, 43%), and Type III (hooked, 39%), with Type III showing the highest association with full-thickness rotator cuff tears⁶.

Patient vignette

42-year-old male competitive tennis player presenting with a 4-month history of progressive anterolateral shoulder pain exacerbated by overhead serving and reaching behind the back. Experiences a painful arc (60°-120°) during movement and night discomfort when sleeping on the affected shoulder.

Physical examination & diagnostics

Neer sign: positive pain response on passive forced forward flexion with the arm internally rotated².
Hawkins-Kennedy test: pain elicited by passive internal rotation at 90° forward flexion.
Jobe (empty can) test: pain or weakness during resisted elevation in the scapular plane with thumbs pointed down.

Imaging slot · Scapular-Y & MRI outlet viewBigliani Type III acromial spur

In-office subacromial infiltration

Technique: posterolateral approach. Needle inserted 1-2 cm inferior to the posterolateral border of the acromion, directed toward the undersurface of the acromion tip.

Injectate mix: 5 mL 1% lidocaine + 40 mg methylprednisolone or triamcinolone acetonide.

Arthroscopic subacromial decompression (SAD)

Under arthroscopic visualization from the posterior portal, a lateral working portal is established². A high-speed burr resects the anteroinferior acromial spur, converting a Type II/III acromion into a flat Type I arch alongside subacromial bursectomy².

Rehabilitation protocol

Phase I (weeks 0-2): sling for comfort, early PROM and active-assisted ROM.
Phase II (weeks 2-6): full AROM, scapular stabilization, rotator cuff isometric strengthening.
Phase III (weeks 6+): progressive resistance training and sports-specific functional conditioning.

03

Clinical pathway · Rotator cuff

Rotator Cuff Pathology & Repair Techniques

Goutallier⁷ Cofield¹ —

A spectrum ranging from tendinopathy and partial-thickness tears to massive full-thickness retractions with fatty degeneration⁷.

Clinical snapshot

Nerve injury risk

Suprascapular nerve: vulnerable at the spinoglenoid notch during extensive posterior tendon retraction releases¹.

X-ray sign

Acromiohumeral interval (AHI): normal > 7 mm. AHI < 7 mm on the AP view indicates a massive supraspinatus tear with superior migration¹.

Clinical pathway

Pathophysiology & classification

Rotator cuff tears stem from intrinsic age-related hypovascular degeneration and extrinsic mechanical impingement¹. Progression leads to muscle atrophy and irreversible fatty infiltration, graded 0-4 using the Goutallier CT/MRI classification⁷.

Patient vignette

58-year-old active female architect reporting sudden sharp lateral shoulder pain and abduction weakness after catching a heavy falling object 3 months ago. Experiences marked difficulty elevating the arm to dress and severe sleep disruption due to night pain.

Physical examination & imaging

Drop-arm sign: inability to smoothly decelerate the arm from 90° passive abduction.
External rotation lag sign: inability to hold the shoulder in full external rotation (infraspinatus).
Belly-press test: assesses subscapularis power.

Imaging slot · MRI T2 coronal viewFull-thickness supraspinatus tear retraction

In-office infiltration

Ultrasound-guided diagnostic subacromial injection: 4 mL 1% lidocaine + 40 mg Depo-Medrol to differentiate pain-inhibited strength from true structural disruption.

Arthroscopic double-row suture bridge repair

The footprint at the greater tubercle is debrided down to bleeding bone¹. Medial suture anchors are placed at the articular margin; suture tails are passed through the tendon footprint and secured laterally with sutureless anchors to restore anatomic footprint contact area¹.

Postoperative rehabilitation

Weeks 0-6: abduction sling immobilization. PROM limited to 120° elevation and 30° external rotation.
Weeks 6-12: discontinue sling; initiate AAROM and active ROM.
Weeks 12+: progressive resistive strengthening; avoid full loading until 6 months.

04

Clinical pathway · Biceps & labrum

Long Head of Biceps & SLAP Lesions

Snyder⁴ O'Brien⁸ —

Pathology of the superior labrum anterior to posterior (SLAP) and instability or tendinopathy of the long head of biceps tendon (LHBT)⁴.

Clinical snapshot

Vascularity

Bicipital branch of the anterior humeral circumflex artery supplies the tendon within the groove³.

MRA landmark

Coronal T1 MR arthrography shows high-signal gadolinium undercutting the superior labral anchor (Snyder Type II)⁴.

Clinical pathway

Anatomy & Snyder classification

Snyder classified superior labral tears into Types I-IV⁴. Type II (fraying with detachment of the biceps anchor from the superior glenoid tubercle) is the most common clinical variant⁴.

Patient vignette

27-year-old male overhead athlete reporting deep anterior shoulder catching, painful clicking, and loss of throwing velocity after a snatch lift. Pain exacerbated by overhead pulling activities.

Physical exam & diagnostics

O'Brien test: deep joint pain with resisted elevation in 10° adduction/internal rotation, relieved by supination⁸.
Speed's test: pain in the bicipital groove with resisted elevation and the forearm supinated.
Yergason's test: pain during resisted supination/external rotation with the elbow flexed 90°³.

Imaging slot · Coronal T1 MRAType II SLAP lesion with gadolinium undercutting

In-office bicipital groove infiltration

High-frequency linear ultrasound guidance targeting the bicipital sheath inside the bicipital groove: 3 mL 1% lidocaine + 20 mg Depo-Medrol.

Arthroscopic biceps tenodesis / tenotomy

The tendon is released from the superior glenoid anchor and fixed extra-articularly into the bicipital groove or subpectoral region using an interference screw or suture anchor to avoid post-op stiffness³.

Rehabilitation guidelines

Weeks 0-4: sling support; avoid active elbow flexion and forearm supination.
Weeks 4-8: active elbow flexion without load; gradual restoration of full ROM.
Weeks 8+: progressive biceps dynamic resistance strengthening.

05

Clinical pathway · AC joint

Acromioclavicular Joint Pathology

Rockwood I–VI¹ —

Degenerative arthrosis, post-traumatic osteolysis, and acute dislocation of the acromioclavicular (AC) and coracoclavicular (CC) ligament complex¹.

Clinical snapshot

Zanca view

Beam centred on the AC joint with 10-15° cephalic tilt and 50% exposure reduction to highlight joint widening and osteolysis¹.

Ligament anatomy

CC ligaments: conoid (medial/posterior) and trapezoid (lateral/anterior) provide vertical stability. AC ligaments provide horizontal stability¹.

Clinical pathway

Pathophysiology & classification

Rockwood classification: Type I (sprain), Type II (AC disruption, CC intact), Type III (100% distal clavicle displacement), Type IV (posterior displacement into trapezius), Type V (>100% displacement), Type VI (inferior displacement beneath the coracoid)¹.

Patient vignette

31-year-old mountain cyclist presenting with localized superior shoulder pain and a visible step-off deformity at the distal clavicle after a direct lateral shoulder crash.

Physical examination & imaging

Step-off deformity: palpable elevation of the distal clavicle.
Cross-body adduction test: pain over the superior AC joint line during horizontal adduction.
Paxinos test: thumb pressure on the posterior acromion + index pressure on the distal clavicle reproduces pain.

Imaging slot · Zanca radiographType III/V AC joint displacement

In-office AC joint infiltration

Palpate the superior notch between clavicle and acromion; 25-gauge needle inserted superior-to-inferior: 1.5 mL 1% lidocaine + 20 mg triamcinolone acetonide.

Surgical reconstruction

Indicated for high-grade Rockwood IV/V/refractory III. Reconstruction uses cortical fixation button devices (e.g., TightRope) or a tendon graft passed through clavicle and coracoid bone tunnels, alongside distal clavicle resection (Mumford procedure, 5-8 mm) if degenerate¹.

Rehabilitation protocol

Weeks 0-6: sling support to reduce vertical clavicular shear forces.
Weeks 6-12: gentle ROM restoration below 90° elevation; progressive trapezius/deltoid activation.
Weeks 12+: return to full overhead function and sport activities.

06

Clinical pathway · Calcific tendinitis

Calcific Tendinitis of the Rotator Cuff

Uhthoff phases⁵ —

Cell-mediated calcium hydroxyapatite deposition within the rotator cuff tendons, driven by local tissue hypoxia and metaplasia⁵.

Clinical snapshot

Radiographic phase signs

Formative phase: dense, sharply demarcated radiopaque deposit⁵.
Resorptive phase: fluffy, ill-defined, translucent deposit (toothpaste consistency)⁵.

Clinical pathway

Uhthoff pathophysiological phases

1. Pre-calcific phase: fibrocartilaginous metaplasia of tenocytes⁵.
2. Calcific phase: formative subphase (accumulation) and resorptive subphase (vascular invasion, macrophage phagocytosis; severe acute clinical pain flare)⁵.
3. Post-calcific phase: collagen remodeling and tendon reconstitution⁵.

Patient vignette

49-year-old female high school teacher presenting to the ER with agonizing, hyperacute shoulder pain without trauma. Arm held immovably against the torso; severe pain on light touch (resorptive phase flare).

Physical exam & diagnostics

Guarding: severe limitation of active and passive movements due to acute bursal pressure.
Tenderness: exquisite tenderness on direct palpation over the anterior greater tubercle.

Imaging slot · AP radiograph & ultrasoundFluffy calcific deposit in supraspinatus

US-guided needle barbotage & infiltration

Under real-time ultrasound guidance, two 18-gauge needles penetrate the calcific deposit. Repeated saline lavage aspirates the fluid calcium deposit. The subacromial bursa is then injected with 40 mg methylprednisolone to manage secondary bursitis.

Arthroscopic evacuation

Indicated for refractory chronic pain. The tendon is identified, probed, and incised parallel to its fibers to evacuate calcific material⁵. The cavity is irrigated thoroughly; residual defects are repaired with suture anchors if necessary.

Rehabilitation protocol

Days 1-7: early passive-assisted pendulum exercises as tolerated.
Weeks 2-4: full active ROM and progressive resistance strengthening as the inflammatory phase settles.

07

Clinical pathway · Frozen shoulder

Adhesive Capsulitis (Frozen Shoulder)

Neviaser⁹ Zuckerman¹ —

Fibroblastic proliferation and capsular contracture, localized predominantly in the rotator interval and axillary recess⁹.

Clinical snapshot

Risk factors

Diabetes mellitus (up to 20% incidence), thyroid dysfunction, Dupuytren disease, prolonged post-surgical immobilization¹.

MRI key findings

Thickening of the coracohumeral ligament (> 4 mm) and obliterative fat fill in the rotator interval and axillary recess⁹.

Clinical pathway

Pathophysiology & stages

Cytokine-mediated inflammatory synovitis leading to capsular fibrosis (elevated TGF-beta)⁹. Phases: 1. Freezing (painful), 2. Frozen (stiff), 3. Thawing⁹.

Patient vignette

54-year-old female patient with type 2 diabetes presenting with a 6-month history of insidious shoulder stiffness and night pain. Unable to reach behind her back or reach overhead into cabinets.

Physical examination & imaging

Global loss of ROM: equal restriction of both active and passive range of motion, most notably external rotation with the arm at the side (< 15°)¹.
Scapular hike: early compensatory scapulothoracic elevation during abduction attempts.

Imaging slot · MRI axillary recessAxillary recess capsule contracture

Glenohumeral hydrodilatation & infiltration

Ultrasound-guided posterior glenohumeral injection: 40 mg triamcinolone acetonide + 4 mL 1% lidocaine + 15-20 mL normal saline to distend the capsule and rupture adhesions.

Manipulation under anesthesia (MUA) & release

If conservative therapy fails after 6 months. Controlled, sequential manipulation into flexion, abduction, and rotation, combined with arthroscopic 360° capsular release (releasing the rotator interval, coracohumeral ligament, and inferior capsule)⁹.

Rehabilitation guidelines

Day 1 post-op: immediate intensive physical therapy within 24 hours to preserve capsular volume.
Weeks 1-6: daily stretching routines targeting end-range external rotation and elevation.

08

Clinical pathway · Instability

Anterior Shoulder Instability & Labral Tears

Bankart¹⁰ Hill-Sachs¹ —

Traumatic anterior glenohumeral dislocation resulting in labral detachment and bone loss¹⁰.

Clinical snapshot

Axillary nerve risk

The axillary nerve runs 3-5 mm inferior to the glenoid capsule at the 6 o'clock position; vulnerable during inferior capsular release/anchoring¹.

Bone loss quantification

3D CT en-face glenoid view: glenoid bone loss > 15-20% predicts failure of isolated Bankart repair and requires Latarjet bone block transfer¹⁰.

Clinical pathway

Pathophysiology & lesions

Bankart lesion: avulsion of the anteroinferior labrum and inferior glenohumeral ligament complex (IGHLC)¹⁰.
Hill-Sachs lesion: posterolateral humeral head impression fracture caused by impact against the anterior glenoid rim¹.

Patient vignette

21-year-old male rugby athlete presenting with persistent apprehension and fear of dislocation when cocking the arm to throw, following a traumatic anterior dislocation reduced in the ER 2 weeks ago.

Physical examination & diagnostics

Apprehension test: anxiety and resistance when the shoulder is brought to 90° abduction and full external rotation.
Jobe relocation test: reduction of apprehension when a posterior force is applied to the anterior proximal humerus.

Imaging slot · 3D CT en-face viewGlenoid bone loss & Hill-Sachs defect

In-office infiltration

Diagnostic intra-articular lidocaine injection (5 mL 1%) used to differentiate true mechanical instability from painful rotator cuff weakness prior to rehabilitation.

Arthroscopic Bankart vs. open Latarjet

If glenoid bone loss is < 15%, an arthroscopic Bankart repair is performed using suture anchors placed at the anteroinferior rim (3 to 6 o'clock)¹⁰. If bone loss is > 15-20%, an open Latarjet procedure is performed (coracoid process transfer with the short head of biceps to the anterior glenoid rim)¹⁰.

Rehabilitation protocol

Weeks 0-4: sling immobilization. Restrict external rotation beyond neutral (0°) to protect the anterior repair.
Weeks 4-8: gradual increase in external rotation (up to 30°) and elevation.
Months 3-6: plyometrics and sports-specific functional training; return to contact play at 6 months.