Glenohumeral Arthritis (Shoulder Arthritis) - Shoulder & Elbow

summary
- Glenohumeral arthritis, or Shoulder Arthritis, is a degenerative joint disease of the shoulder characterized by damage to the articular surfaces of the humeral head and/or glenoid.
- Diagnosis is made radiographically with true AP shoulder ("Grashey") and axillary lateral radiographs.
- Treatment is observation, NSAIDs, and corticosteroids for minimally symptomatic patients. Shoulder arthroplasty is indicated for progressive symptoms with severe degenerative disease.

Epidemiology
- Incidence
  - increases with age
    
    more likely in patients over 60
- Demographics
  - more common in women
- Risk factors
  - 56% of patients who had primary anterior dislocation have arthrosis at 25 years follow up

Etiology
- Causes
  - primary osteoarthritis
  - secondary arthritis
    
    post-traumatic
    
    arthritis of dislocation
    
    inflammatory/crystalline arthritis
    
    osteonecrosis
    
    neuropathic (Charcot Arthropathy)
    
    rotator cuff arthropathy
- Pathophysiology
  - primary osteoarthritis
    
    articular cartilage
    
    irreversible progressive loss of articular cartilage with hypertrophic reaction of the subchondral bone; no known cause
    
    humeral head
    
    thinning/absence of cartilage, flattening, osteophyte and subchondral cyst formation, posterior humeral subluxation
    
    glenoid
    
    posterior wear (see: Walch glenoid classification), subchondral cyst formation
    
    rotator cuff
    
    rotator cuff tears incidence 5-10%, important to rule out
  - post-traumatic arthritis
    
    articular surface incongruities following trauma healing can lead to joint deterioration
    
    commonly occurs in patients with humeral fractures and chronic dislocations
  - cuff tear arthropathy
    
    torn rotator cuff tendons leads to humeral head migration and subsequent abrasive contact between the humeral head and acromion which leads to articular wear
  - dislocation arthropathy
    
    repeated dislocation can cause erosion of joint cartilage
    
    higher incidence with
    
    increased age
    
    posterior dislocation
    
    not associated with number of dislocations
  - post-capsulorraphy arthropathy
    
    excessive tightening of soft tissues in stabilization surgeries to treat recurrent dislocation forces humeral head in one direction
    
    causes head to wear unevenly on glenoid
  - inflammatory/crystalline arthritis
    
    rheumatoid arthritis
    
    systemic autoimmune disease causes synovial inflammation and degradation of shoulder joint
    
    can involve all structures of shoulder including soft tissue
    
    affects 90% of patient with RA
    
    characterized by central glenoid wear and medialization of humeral head
    
    calcium pyrophosphate dihydrate deposition disease (CPPD)
    
    accumulation of calcium pyrophosphate crystals within joint space causing synovial inflammatory response and cartilage/bone damage; sometimes referred to as “pseudogout”
    
    gout
    
    accumulation of sodium urate crystals within joint due to hyperuricemia causing inflammatory attack within joint and cartilage/bone damage
  - osteonecrosis/avascular necrosis
    
    bone cell death caused by interruption of blood supply to humeral head leads to subchondral bone collapse and morphological/arthritic changes
    
    causes
    
    traumatic
    
    proximal humerus fractures
    
    35% incidence in 3-part
    
    90% incidence in 4-part
    
    chronic glenohumeral dislocations
    
    repetitive injury
    
    rotator cuff repair
    
    atraumatic
    
    steroid
    
    ETOH
    
    hemoglobinopathies
    
    metabolic (e.g. Gaucher’s disease
  - chondrolysis
    
    occurs following shoulder arthroscopy
    
    exact pathophysiology unknow but associated with
    
    radiofrequency energy
    
    continuous postop anesthetic infusion
    
    bioabsorbable suture anchors
    
    contrast
    
    leads to the dissolution of articular cartilage
    
    has less osteophytes than OA
- Associated conditions
  - rotator cuff tears
    
    5-10% incidence with OA
    
    25-50% incidence with RA

Anatomy
- Glenohumeral (GH) joint
  - joint comprised of humeral head and glenoid fossa of scapula
  - stability
    
    static restraints
    
    glenohumeral ligaments
    
    glenoid labrum
    
    dynamic restraints
    
    rotator cuff muscles
    
    rotator interval
    
    biceps
- Glenoid osteology
  - glenoid is 3 degreees retroverted
  - humerus is 20-30 degrees retroverted

                        Classification
                    
                        Walch Classification of Glenoid Wear
                    
                        Type A
                    
                        Concentric wear, no subluxation of HH, well centered
                    
                        A1: no or minor central erosion
                    
                        A2: deeper central erosion, line connects anterior/posterior glenoid rims and transects humeral head (HH)
                    
                        Type B
                    
                        Biconcave glenoid, asymmetric glenoid wear and head subluxated posteriorly
                    
                        B0: pre-osteoarthritic posterior subluxation of HH
                    
                        B1: posterior joint narrowing (no posterior bone loss), osteophytes, subchondral sclerosis
                    
                        B2: posterior rim erosion, retroverted glenoid
                    
                        B3: mono-concave, posterior wear, at least HH subluxation >70% OR retroversion >15%
                    
                        Type C
                    
                        C1: Glenoid retroversion >25 degrees, regardless of erosion
                    
                        C2: Biconcave, posterior bone loss, posterior translation of HH
                    
                        Type D
                    
                        Glenoid anteversion or anterior HH subluxation (HH subluxation <40%)

Presentation
- Symptoms
  - shoulder pain
    
    worse with activities involving shoulder motion
    
    often no pain at rest
  - loss of range of motion
    
    especially external rotation due to anterior capsule contraction
  - difficulty sleeping
- Physical exam
  - functional limitations at glenohumeral joint
    
    decreased external rotation, forward flexion, and internal rotation
    
    variable and more active patients have better range of motion (ROM)
  - crepitus
  - catching/squeaking with articulation
  - motor
    
    a carefully evaluation of the rotator cuff muscles should be performed
- Functional Outcomes Scores
  
  ASES Shoulder Score
  
  Constant Score
  
  Oxford Shoulder Score
  - ASES Shoulder Score
  - Constant Score
  - Oxford Shoulder Score
- ASES Shoulder Score
- Constant Score
- Oxford Shoulder Score

Imaging
- Radiographs
  - recommended views
    
    true anteroposterior (AP) of GH joint
    
    AP
    
    axillary lateral
  - findings often diagnose etiology
    
    primary osteoarthritis
    
    joint space narrowing
    
    subchondral sclerosis, subchondral cysts
    
    osteophytes circumferentially at humeral head, “goat’s beard”
    
    posterior glenoid wear
    
    fixed posterior humeral head subluxation (due to tight anterior capsule)
    
    post-traumatic arthritis
    
    articular surface incongruities due to healed fractures
    
    hardware from previous surgeries
    
    arthritis of dislocation
    
    large osteophytes
    
    hardware from previous surgery
    
    inflammatory/crystalline arthritis
    
    RA
    
    joint space narrowing
    
    marginal erosions of humeral head
    
    reduction in acromiohumeral distance
    
    few osteophytes
    
    central glenoid wear and medialization of humeral head
    
    osteopenia
    
    CPPD
    
    chondrocalcinosis (calcific deposits in articular/fibrocartilage)
    
    Gout
    
    usually unremarkable
    
    repeat attacks may show osteopenia/erosions
    
    osteonecrosis/avascular necrosis
    
    normal radiographs early in disease
    
    resorption of middle of humeral head
    
    crescent sign (lucency) indicating subchondral collapse
    
    flattening/collapse in more advanced stages
    
    rotator cuff tear arthropathy
    
    osteopenia
    
    superior migration of humeral head
    
    narrowing of acromiohumeral interval
    
    acromial erosions
    
    superior glenoid bone loss
    
    “acetabularization” of coracoacromial arch
- Computed tomography (CT)
  - indications
    
    evaluate glenoid morphology and rotator cuff pathology for pre-operative planning
    
    may underestimate full-thickness RCTs and fatty infiltration/muscle atrophy compared to MRI
    
    allows for pre-operative templating
- Magnetic Resonance Imaging (MRI)
  - indications
    
    evaluate rotator cuff pathology for pre-operative planning
    
    less accurate than CT in distinguishing between glenoid types

Treatment
- Nonoperative
  - physical therapy, NSAIDs
    
    indications
    
    first-line of treatment
    
    modalities
    
    NSAIDs- reduce pain and inflammation
    
    physical therapy – improve range of motion with capsular stretching
  - intraarticular Injections
    
    indications
    
    second-line of treatment
    
    modality
    
    corticosteroid injection – reduce pain/inflammation
    
    hyaluronic acid injection – joint lubrication, limited evidence
    
    biologics (platelet rich plasma, stem cell) – limited evidence
  - DMARDs
    
    indications
    
    rheumatoid arthritis
- Operative
  - total shoulder arthroplasty (TSA)
    
    indications
    
    intact rotator cuff
    
    unresponsive to non-operative treatment
    
    glenoid chondral wear
    
    posterior humeral head subluxation
    
    contraindications
    
    lack of deltoid or rotator cuff function
    
    active infection
    
    Charcot arthropathy
    
    technique
    
    concave glenoid (cup) and convex humerus (ball) to reconstruct joint
    
    outcomes
    
    good pain relief, reliable ROM
    
    10 year survival (92-95%)
    
    most common complications: glenoid/humeral component loosening, infection, fracture, nerve injury and rotator cuff tear
  - hemiarthroplasty
    
    indications
    
    younger patient
    
    rheumatoid arthritic patients with irreparable RC tears/insufficient bone stock
    
    osteonecrosis without glenoid involvement
    
    technique
    
    humeral head replacement ± biologic resurfacing
    
    ream-and-run technique
    
    humeral head prosthesis & glenoid reaming to provide a stabilizing concavity and maximize glenohumeral contact area for load transfer
    
    indicated in young patients with intact rotator cuff and no inflamatory arthropathy
    
    outcomes
    
    early failure rate, not recommended
    
    poor pain and functional outcomes
  - reverse shoulder arthroplasty (RSA)
    
    indications
    
    irreparable/large rotator cuff tear
    
    OA or RA with significant glenoid pathology
    
    age
    
    rotator cuff arthropathy
    
    failed arthroplasty
    
    complex fracture
    
    technique
    
    convex glenoid (ball) and concave humerus (cup) to reconstruct joint
    
    outcomes
    
    Good pain relief, improved shoulder function
    
    10 year survival (~90-95%)
    
    Common complications: scapular notching, infection, dislocation/instability, nerve injuries; higher reported complication rates than TSA
  - arthroscopic debridement
    
    indications
    
    mild to moderate OA without structural alternation
    
    mechanical symptoms due to loose bodies or small lesions of humeral head due to AVN
    
    synovial chondromatosis
    
    outcomes
    
    temporizing treatment; improves ROM and pain
    
    less successful in those with more rapid degenerative changes
    
    higher rates of failure in those with more preoperative joint space narrowing and posterior glenoid wear
    
    may see better results in patients who also had subacromial procedures
  - CAM (comprehensive arthroscopic management) procedure
    
    indications
    
    younger patient
    
    technique
    
    combination of arthroscopic glenohumeral debridement, chondroplasty, synovectomy, loose body removal, humeral osteoplasty with excision of the goat's beard osteophyte, capsular releases, subacromial and subcoracoid decompressions, axillary nerve decompression, and biceps tenodesis
  - arthrodesis
    
    indications
    
    paralysis
    
    recurrent infection
    
    severe soft tissue deficiency; poor deltoid function
    
    brachial plexus palsy
    
    persistent symptomatic instability with failed repair
    
    outcomes
    
    moderate complications
    
    Improved/ acceptable long-term function

Techniques
- Total shoulder arthroplasty
- Hemiarthroplasty
- Reverse ball prosthesis

Action	Numeric Key	Letter Key	Function Key
Show Bullets		S	Enter (frontside only)
20%	1	N
40%	2	H
60%	3	F	Enter (backside only)
80%	4	E
100%	5	M
Toss	0	T

Walch Classification of Glenoid Wear
Type A	Concentric wear, no subluxation of HH, well centered A1: no or minor central erosion A2: deeper central erosion, line connects anterior/posterior glenoid rims and transects humeral head (HH)
Type B	Biconcave glenoid, asymmetric glenoid wear and head subluxated posteriorly B0: pre-osteoarthritic posterior subluxation of HH B1: posterior joint narrowing (no posterior bone loss), osteophytes, subchondral sclerosis B2: posterior rim erosion, retroverted glenoid B3: mono-concave, posterior wear, at least HH subluxation >70% OR retroversion >15%
Type C	C1: Glenoid retroversion >25 degrees, regardless of erosion C2: Biconcave, posterior bone loss, posterior translation of HH
Type D	Glenoid anteversion or anterior HH subluxation (HH subluxation <40%)