Glenohumeral Arthritis

Introduction

Definition
- glenohumeral degenerative joint disease characterized by damage to the articular surfaces of the humeral head and/or glenoid
Etiology
- causes include
  - primary osteoarthritis
  - secondary arthritis
    - post-traumatic
    - arthritis of dislocation
    - inflammatory/crystalline arthritis
    - osteonecrosis
    - neuropathic (Charcot Arthropathy)
    - rotator cuff arthropathy
Epidemiology
- incidence increases with age
  - more likely in patients over 60
- OA more common in women
- 56% of patients who had primary anterior dislocation have arthrosis at 25 years follow up
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 monoconcave, 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
F
unctional Outcomes Scores
- 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 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
    - 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

Reverse Total Shoulder Arthroplasty

Total Shoulder Arthroplasty

Proximal Humerus Fracture Hemiarthroplasty

Indications for Shoulder Arthroplasty in Athletic Patients - Eric McCarty, MD (2.3, 2018 Winter SKS)

Nonarthroplasty Management of Cartilage Loss - Matthew Provencher, MD, CAPT, MC, USNR(2.2, 2018 Winter SKS)

SHOULDER - Arthritis in the Athletic Patient - Anthony Romeo, MD (2.1, 2018 Winter SKS)

Proximal humeral deformity/malunion in a 35M (C101077)

Post-traumatic shoulder OA with cuff failure in a young patient (C2331)

Shoulder instability/DJD (C1536)