Overview of Shoulder Anatomy
- Proximal humeral Fx account for 4-6% of all Fxs. Osteoporotic (OSP) Fx in >60 y.o associated with minimal trauma with F: M 2:1 ratio. In young patients, acute high energy trauma predominates.
- Complications: AVN humeral head, Axillary N paralysis.
- Neer Classification: considers fractures along 4-anatomical lines with or w/o displacement >1-cm & 45-degree angulation
- One part Neer Fx- no displacement or very minimal <1-cm/45-degree. Can affect 1-4 lines and M/C at greater tuberosity. 80% of proximal humeral Fx are one-part Neer.
- Two-part Fx: 1-part is displaced >1-cm/45-degrees. m/c involves the surgical neck
- Three-part Fx: 2-parts are displaced >1-cm/45-degrees.
- Four-part Fx: all 4-parts can be displaced. Uncommon <1%
- Imaging: 1st step-radiography, CT may be used in more complex cases. Orthopedic referral
- Management: Neer one-part Fx is treated with Sling Immobilisation and progressive rehab
- The vast majority of Fx in the elderly are treated non-operatively
- Younger patients (40-65) may occasionally require hemiarthroplasty if 3 or 4-part Neer Fx present. Greater risk of AVN
Proximal Humerus Fractures
- Note: Left image: Fx involving the anatomical neck and the greater tuberosity with minimal displacement <1-cm/45-degree thus Dx as one-part Fx. Right image: Small avulsion Fx of the greater tuberosity with significant displacement (>45-degrees & 1-cm) thus Dx as two-part Fx
- Note: three-part Neer Fx (left) and four-part Neer Fx (right)> Management: operative in most cases in younger (40-65) patients
Shoulder Dislocation aka Glenohumeral Joint dislocation (GHJD)
- Refers to complete separation of the humerus from scapula glenoid. In 20-40s M: F 9:1 ratio, in60-80S M: F 3:1
- Anatomy: Shoulder stability is sacrificed for mobility, and overall GHJD is the m/c among large joints in the body
- Protective falls (e.g., FOOSH) and MVA are m/c causes. GHJ is most vulnerable in abduction, extension and external rotation. Anatomical factors: shallow glenoid, laxed ant-inferior capsule and GH ligaments. GHJD will induce severe tearing of major GHJ restraints. Associated osseous and labral injuries are common and may lead to chronic instability, DJD,�and functional changes
- 3-types: Anterior GHJD (95%)
- Posterior GHJD (4%) especially associated with epileptic seizures, electrocution and can occur b/l
- Inferior GHJD aka Laxatio Erecta (<1%) associated with severe trauma
- Clinically: AGHJD presents with severe pain, the arm is externally rotated and adducted, severe limitation of movement. GHJD may persist as chronic dislocation.
- Management: prompt reduction in ED under anesthesia or heavy sedation with Kocher technique top image (not used), External rotation method (middle) or Milch technique (can be used w/o anesthesia) and a few other methods. Delay in reduction correlates with greater risk of immediate and long-term�complications
Diagnostic Imaging Approach
- Shoulder series x-radiography is sufficient. Additional Imaging with CT scanning and MRI may be helpful to Dx osseous, cartilage, labral/ligaments pathology
- Anterior GHJD (95%). Subcoracoid position(top right) of the humerus is the m/c
- Anterior GHJD may also occur as subglenoid(bottom left)and infrequently as subclavicular
- Key to radiographic search is to evaluate associated Bankart and Hill-Sachs injuries
- Occurs during anterior GHJD d/t impaction of the head into anterior-inferior glenoid. Variations exist (see next slide). BonyBankart can be seen on x-rays. So-called soft tissue Bankart requires MRI. Cartilage (soft)Bankart is the m/c.
- Hill-Sachs aka Hatchet deformity (arrow postreduction)occurs during the same mechanism as Bankart, i.e., compression and impaction of posterolateral aspect of the head against the glenoid producing wedge-shape Fx. Hill-Sachs lesion may predispose to recurrent/chronic GHJD.
- Bankart lesion may heal, but operative suture anchors are needed sometimes
- CT arthrogram and MRI may be helpful
Types of Bankart Lesion
- Note different types of Bankart lesion. Onlyosseous Bankart can be seen radiographically. Soft tissue Bankart requires MRI with and without intra-articular gadolinium(arthrogram).
- Note: posterior GHJD with its characteristic signs:
- Trough sign aka reverse Hill-Sachs. Occurs d/t anterolateral head impaction Fx
- Rim sign: only occurs in the PGHJD d/t posterior position of the head and anterior glenoid-to humeral head distance 6-mm or greater
- Light-bulb sign: d/t acute internal rotation of the humerus (head)
- Inferior GHJD aka Laxatio Erecta
- Severe hyperabduction and inferior displacement of the humerus. Greater chances of severe neurovascular injury and acromial Fx
- The dislocated arm is hyperabducted and fixed with the elbow flexed and the arm above the head
ACJ Dislocation (ACJD)
- ACJD: common injury, 9% of shoulder girdle injuries esp. in male athletes by a direct blow
- Rockwood classification (left) evaluates tearing of AC and CC ligaments and regional muscles
- Type1, 2, 3 among the m/c
- Type 1: sprain of ACL w/o tearing
- Type 2: tear of ACL and sprain of CCL
- Type 3: tear of AC & CCL. The clavicle is elevated above the acromion. If <2-cm good results with conservative Rx.
- Imaging: x-radiography with b/l ACJ views with and w/o weights to compare both ACJs. In complex cases CT scanning esp. if Fx is considered
- Management: Type 3 (>2-cm) & Types 4-6Operative
Type 3 ACJ Separation
- Type 3 ACJ separation (top left)
- More significant ACJD (bottom images) with clinical sign of acromion under the skin and resultant ORIF
Rotator Cuff Muscles (RCM) Pathology
- RCM tendinopathy: collagenous degeneration of RCM particularly Supraspinatus M. tendon(SSMT) d/t overuse/degeneration-micro tearing with collagenous replacement. Impingement syndrome is a 2nd extrinsic cause. Presented clinically as pain and limited ROM
- Imaging Dx: MSK US can be as accurate as MRI and better in some cases d/t dynamic evaluation v. cost effective
- Key MRI clue is thickened inhomogeneous SSMTwith increased signal on all pulse sequences d/t fatty degeneration and inflammation (left images: T1 & T2 FS)
- MSKUS findings: thickening of the SSMTsubstance with a change�in normal echogenicity.MSKUS is good to DDx with SSMT tears. US advantages are that it allows dynamic evaluation of painful structures
- Partial tear of SSMT: partial (incomplete) tear ofSSMT may occur at the bursal and articular surface or interstitial, i.e., intra-substance/noncommunicating. Etiology: sub-acromial impingement, acute strain, and chronic microtrauma tendinosis
- Clinically: pain on abd and flexion, impingement tests, Hawkins-Kennedy tests, etc. Pearls: partial tears can be more painful than complete tears
- Imaging Dx: MSKUS is as good as MRI (N.B.some studies indicated MSKUS is more superior to MRI). Key MRI findings: gap/incomplete tear of SSMT filled with joint fluid +/- granulation tissue
- MSKUS: decreased echogenicity of SSMT, thinning and partial tearing filled with fluid(anechoic areas arrows). Lost convexity of tendon bursal or articular interface.
- Full Thickness SSMT (rot cuff) tear: degeneration/tearing of rot cuff. 2nd to impingement by Hooked acromion, overhead overuse or acute trauma. 7-25% of shoulder pain in the general population. Clinically: pain on impingement tests.
- Imaging Dx: MSKUS is as good as MRI.Limitations: poor Dx of labral pathology. Key USDx: focal tendon interruption, an anechoic gap (fluid filled), hypoechoic tendon, tendon retraction, uncovered cartilage sign (bottom left, A: US B: MRI)
- MRI: key Dx: insertional tear extending through entire SSMT crescent, retraction with fatty degeneration of SSMT and the muscle. If retraction is at 12 o�clock or greater (top images), it may not be anchored operatively
- Rotator Cuff (RTC) Calcific Tendinitis: usually d/t calcium HADD crystals. Middle-aged women are most affected. Ranges from asymptomatic imaging finding to severe destructive arthropathy or Milwaukee shoulder(infrequent)
- HADD has 3-pathological phases: formation resting-resorption.Mild-to-moderate pain esp. in resting phase.
- Imaging: x-radiography: homogenous ovoid mineralization within RTCMT, m/c in SSMT. MRI: ovoid/globular decreased signal on all pulse sequences often with surrounding edema (bottom left)
- Rx: self-resolution occurs. Advanced cases: operative aspiration etc.
Superior Labrum Anterior to Posterior (SLAP) Lesions/Tears
- SLAP tears: FOOSH and throwing sports or chronic shoulder instability aka Multidirectional shoulder instability (in 20%). Type 1-9 exist but the M/C areType 1-4
- In all 4-types superior labrum is affected with or w/oLHBMT anchor tear (see pictures). Clinically: pain, limitation of AROM with active compression tests, typically non-specific findings mimicking RTCpathology
- Imaging is crucial: best imaging is MRI arthrography. Key signs: hyperintense linear fluid signal within superior labrum +/- extending along the LHBT on fat-suppressed fluid sensitive imaging and FS T1 arthrogram. Best observed on coronal slices.
- Rx: small tears may heal, but unstable tears require operative care.
- Key DDx: anatomical variants like Buford complex andSub-labral foramen
- SLAP tear with a paralabral cyst (bottom right)
- Normal variant DDx: sub labral foramen(bottom left) note: MR arthrography with contrast undercutting the labrum but w/o extending posteriorly to the LHBT
- GHJ DJD: usually associated with a 2nd cause: trauma, instability, AVN, CPPD, etc. Presented with pain, crepitus and decreased ROM/function. Associated RTC disease may be present. Imaging; x-radiography is sufficient and provides grading/care planning.Major findings: joint narrowing, osteophytosis esp. at the inferior-medial head (orange arrow), subchondral sclerosis/cysts. Often noted superior head migration d/t RTC disease.
- ACJ OA: common and typically primary with aging. Presents with ACJ loss and osteophytes. Osteophytes along the undersurface of the ACJ �keel osteophytes�(blue arrow) may lead to RTC muscle tear. Regional bursitis is other clinical feature of ACJ arthrosis.
- Management: usually conservative depending on clinical signs/symptoms
- Rheumatoid Arthritis GHJ: RA is a multisystem inflammatory disease affecting multiple joints lined by the synovium. GHJ RA is common (m/c large joints in RA knees/shoulders). Clinically: pain, limited ROM and instability, muscle weakness/wasting. Hands, feet,�and wrists are m/c affected. Imaging: x-radiography reveals periarticular erosions, uniform joint space loss, juxta-articular osteoporosis, subluxations,�and soft tissue swelling. MRI can help detect�commonly associated RTC tearing and instability. Early changes can be detected by MSKUS esp. with power Doppler use indicating hyperemia/inflammation.
- Note: L shoulder x-ray revealing cartilage destruction and symmetrical joint loss, multiple erosions, and likely loss of RTCM support with superior head migration, ST effusion present.
- Note: PDFS coronal and axial MRI slices of GHJ RA indicating marked inflammatory joint effusion, bone erosion/edema, synovial pannus formation and likely tear in RTC m. Management: Rheumatological referral and pharmacotherapy with DMARD. Operative care asRTCM repair. 10% of patients are disabled d/t RA
- Neuropathic Osteoarthropathy aka Charcot’s shoulder: d/t neurovascular and neural periarticular damage. Multiple causes exist.M/c develops in diabetics in midfoot. Shoulder Charcot is m/c in Syringomyelia (25%), trauma paralysis, MS, etc. Dx: clinical(50% pain/swelling 50% painless destruction). Imaging is crucial. X-radiography is sufficient in well-established cases, but early Dx is challenging. MRI may help with early Dx and delayed complications. Rad Dx: Shoulder Charcot is m/c presented as atrophic type destructive arthropathy with humeral head appearing as if surgically amputated along with intra-articular debris, density, distention, dislocation, and other key features
- Septic Shoulder: shoulder is the 3rd m/c followingknee>hips. Patients at risk: diabetics, RA pts, immunocompromised, I.V. drug users, indwelling catheters, etc. Routes: hematogenous (m/c), direct inoculation (iatrogenic, trauma etc.) adjacent spread(e.g. OM). Staph. Aureus (>50%) m/c.
- Clinically: joint pain and dec. ROM, fever 60% only, toxemia, inc. ESR/CRP. Dx: imaging and joint aspiration/culture. RadDx: early x-rays often unremarkable except ST effusion/fat planes obscuration, joint widening. Later7-12 days patchy osteopenia, moth-eaten/permeating bone resorption, articular destruction, joint narrowing. May progress to severe joint destruction and ankyloses. Early Dx & I.V. antibiotics are crucial even before culture. Operative irrigation and joint drainage in some cases. Complications are possible esp. if Rx is delayed. MSKUS with needle aspiration may help. Note: (top image) non-traumatic joint widening with inferolateral head displacement d/t septic A dx: by needle aspiration Staph. Aures.
- Ischemic Osteonecrosis of the humeral head may occur d/t trauma (Neer four-part Fx), Steroids, Lupus, Sickle cell, Alcoholism, Diabetes,�and many other conditions. Imaging is crucial: MRI detects earliest changes as intraosseous edema. X-ray features are late, presented as a collapse of subchondral bone with sclerosis �snow cap� sign, fragmentation, and progressive severe DJD
- Management: orthopedic referral, core decompression in early cases, hemiarthroplasty in moderate and total arthroplasty in severe cases.
- In adults >40, bone Mets d/t lung, breast, renal cell, thyroid CA & prostate are the m/c causes. Clinically: may mimic pain resemblingRTC/joint changes. Should be evaluated carefully. Key to Dx: Hx, PE and Imaging esp.in pts with known primary
- Imaging: 1st step x-rays, MRI can help, Tc99bone scintigraphy helps to detect regional and distant disease. X-ray features: destructive lytic changes typically in prox humerus(red marrow) with or w/o path Fx. DDx: Mets, MM, lymphoma
- Clinically: night pain, pain at rest, etc. Lab tests: unrewarding, in severe cases hypercalcemia may be noted.
- Primary Malignant bone neoplasms (shoulder) Adults: M. Myeloma or Solitary plasmacytoma, Chondrosarcoma may transform from an enchondroma and some others. In children/teenagers: OSA vs. Ewing�s
- Primary benign bone neoplasms (shoulder). Adults: Enchondroma (patients in their 20-30s)GCT. In children: Simple bone cyst (Unicameral Bone cyst), Osteochondroma, Aneurysmal Bone Cyst, Chondroblastoma (rare)
- Imaging: 1st step x-radiography
- MRI is essential to Dx. Especially in cases of primary malignant neoplasms Evaluate extent, soft tissue invasion, preoperative planning, staging, etc.
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