Shoulder Arthroplasty for degenerative disease

Question 1

What are the indications for shoulder Hemiarthroplasty?

Answer 1

• Primary OA if
  
  • RC deficiency
  • glenoid bone stock inadequate
  • risk of glenoid loosening high
    
    • young pts
    • active labourers
• RC arthropathy
• Osteonecrosis wihtout glenoid involvement
• Prox humeral fx
  
  • 3 part w poor bone quality
  • 4 part fx
  • head splitting fx
  • fx with significant destruction of articualr surface

Question 2

What are the CI for shoulder Hemiarthroplasty?

Answer 2

• Infection
• Neuropathic joint
• unmotivated pt
• coracohumeral ligament deficiency
  
  • provides a barrier to humeral head proximal migration in the case of RC tear
  • superior escape will occur if coracoacromial lig and RC are deificient

Question 3

What are the outcomes for hemiarthroplasty?

Answer 3

• In RC def shoulder
  
  • Status of RC is most inflential factor post op function
• in prox humeral fx
  
  • provides excellent pain relief in majority
  • outcomes scores inversely proportional to pts age and time from injury to operation

Question 4

What imaging is helpful prior to shoulder Hemiarthroplasty?

Answer 4

• Xray
  
  • True ap
    
    • determine extent of OA
    • delination of fx pattern
  • axillary view
    
    • look for post glenoid wear
    • helps quantify displacement in fx
• CT
  
  • obtain to determine glenoid version/bone stock
• MRI
  
  • RC evaluation

Question 5

Describe how you would do a shoulder Hemiarthroplasty?

Answer 5

• Beach chair position
• deltapectoral approach
• cemented proethesis
  
  • better quality of life, rom, strength cf uncemented
• humeral head resection
  
  • start osteotomy medial insertion line of supraspinatus
  • determine retroversion, implant height and size
    
    • 30^o retroversion ideal
    • lateral fin slightly post to biceps groove
    • xs anterversion->anterior dislocation
    • xs retroversion->post dislocation
    • height
      
      • GT 3-5mm below top of humerus
      • distance from top of prosthesis head to upper border of pect major = 53mm
• ​​​​​Tuberosity migration
  
  • **​common causes of failure **
  • attention to secure tuberosities to each other and shaft

Question 6

What would rehab be for shoulder Hemiarthroplasty?

Answer 6

• Early passive motion until fx healed
  
  • duration 6-8wks
• Strengthening excercises being once tuberosity has fully healed

Question 7

What are the complications of shoulder Hemiarthroplasty?

Answer 7

• Progressive Glenoid arthrosis
  
  • increased with young, active pts
  • tx= convesion to Total shoulder arthroplasty
• Tuberosity malunion/displacement
  
  • common complx
  • tx= repositing of tuberosity with bone graft
• Joint overstuffing
  
  • -> stiffness, acclerated arthritis of glenoid
• Subcutaneous ( anterosuperior escape)
  
  • when RC and coracoacromial arch deficient

Question 8

What is a total shoulder replacement?

Answer 8

• Replacement of humeral head and glenoid resufacing
  
  • cemented all poly glenoid resurfacing
• unique from TKR/THR in that
  
  • greater ROM in shoulder
  • success depends on of proper functioning of the soft tissues
  • glenoid is less constrained
    
    • leads to greater shear stresses
    • more susceptible to mechanical loosening

Question 9

What are the factors required for a success of TSA?

Answer 9

• Rotator cuff intact and functional
  
  • if RC deficient with proximal migration of humerus- glenoid resurfacing contraindicated
  • RC tear = hemi/reverse ball
• Glenoid bone stock and version
  
  • if glenoid eroded down to coracoid process tehn glenoid resurfacing CI

Question 10

What are the outcomes for TSA?

Answer 10

• Pain relief most predictive benefit
• reliable rom
• good survival at 10 yrs 93%
• good longevity with cemented & press fit humeral components
• Worse for post -capsulorrhahpy arthropathy

Question 11

What are the indications for TSA?

Answer 11

• Pain ( ant/post ) at night & inability to do ADLs
• Glenoid chondral wear
• Posterior head subluxation

Question 12

Describe the contraindications for TSA?

Answer 12

• Insufficient glenoid stock
• RC arthropathy
• Deltoid dysfunction
• Irreparable RC ( HEMI/Reverse shoulder preferable)
  
  • risk of loosening glenoid prosthesis is high ( rocking horse phenomenon)
• Active infection
• brachial plexus palsy

Question 13

Describe the technically side of TSA?

Answer 13

• Beachchair position
• deltapectoral approach
  
  • tight shoulder may require release of upper 1/2 of pectoralis tendon to increase exposure/dislocation- pect major passes ontop of biceps tendon
• Glenoid
  
  • deficiency build up with iliac bone graft
  • convex shape superior to flat
  • recreate neutral version
  • Peg design biomechanically stronger than keel
  • polyethylene backed superior to metal
  • uncemented lower rate of loosening
  • conforming vs non conforming
    
    • non superior
    • conforming is more stable but-> rim stress and radioluciences
    • non conforming -> > poly wear
• Humerus
  
  • uncemented or cemented
  • stem should be 25-45^o retroversion
  • avoid valgus, overstuffing

Question 14

What happens if an intraopertaive fx occurs in the humeral shaft or GT?

Answer 14

• Humeral shaft
  
  • take prosthesis out and use longer stem and reinforce with cerclage wire
• GT fx
  
  • minimal displaced- insert standard humeral prothesis with suture fixation and autogenous cancellous bone graft of GT fx

Question 15

Describe the rehab of TSA?

Answer 15

• Passive or active-assisted motion only during early rehab
  
  • risk of injury to subscapularis
• Progress to ER isometrics
• Limited passive ER
  
  • risk of tear and pull off of subscapularis tendon
  • tear -> ant shoulder instability
  • weak belly press test

Question 16

What are the complications of TSA?

Answer 16

• Glenoid loosening
  
  • 30% primaryOA
  • RF: insufficient glenoid bone stock, RC def
  • 2.9% reop rate for loosening
  • Presence of radiographic line doesn’t correalte with symptoms but progression of line does
• Humeral stem loosening
  
  • most common in RA- rule ou infection
• Subscapularis repair failure
• Malposition of components
• Improper soft tissue balancing
• Iatrogenic RC injury
  
  • if humeral neck ostoetomy if inferior to level of RC insertion
• Stiffness
• Infection
  
  • early < 6 wks= open irrigation/debridement
  • Late >6 wks= explant iv antibiotics and reimplant
• Neurologic injury
  
  • axillary n most commonly injured
  • musculocutaneous n can be injured by retractor placement under conjoint tendon

Question 17

What is a reverse shoulder replacement?

Answer 17

• A hemisphere ball on the glenoid surfacae and artculating cup into humerus
• considered a proceedure with high complx rate for irrepairable RC tears

Question 18

What are the indications for use fo reverse shoulder replacement?

Answer 18

• Pseudoparalysis 2ary to irrepairable RC tear + GH arthritis
• Incompetent coracoacromial arch- humeral escape
• low functional demand pt
• physiological age >70 yrs
• suff glenoid bone stock
• working deltoid muscle - intact axillary nerve

Question 19

What are the contraindications of reverse shoulder replacement?

Answer 19

• Deltoid deficiency
• bony acromion deficiency
• glenoid osteoporosis
• active infection

Question 20

Describe the biomechanics of reverse shoulder replacement?

Answer 20

• The advantage of the reverse shoulder replacment is that the centre of rotation ( COR) is moved Inferiorly and medialised
• which allows the Deltoid to act on a longer fulcrum and have more mechanical adv to substiute for the def RC muscles to provide shoulder abduction
• allow greater by normal shoulder abduction
• doesn’t help with ER/IR

Question 21

Describe the complications of reverse shoulder replacement?

Answer 21

• Gerber showed a 50% complication rate, 33% reop rate & eventually 6 out of 58 reverse balls were removed
• Dislocation
  
  • not related to condition of RC
• Loosening
  
  • glenoid loosening most common failure
• Instability
• Infection
• inferior scapular notching
  
  • increased risk with superiorly placed glenoid components, or insufficient inferior tilt of glenoid component on native glenoid

Question 22

What is the goal of shoulder arthrodesis? indications?

Answer 22

• To provide a stable base for upper extremity optimising hand and elbow function
• Stabilisation in paralytic disorders
• brachial plexus injury
• irrepairble deltoid, RC with arthropathy
• salvage failed TSA
• reconstruction post tumour

Question 23

What are the contraindications for shoulder arthrodesis?

Answer 23

• Ipsilateral elbow arthrodesis
• Controlateral shoulder arthrodesis
• lack of functional scapulothoracic motion
• charot arthropathy
• elderly pts
• progressive neurologic disease

Question 24

Describe the surgical technical approach to a shoulder arthrodesis?

Answer 24

• S shaped skin incision start over scapular spine, transversing anterior over acromium and down the anterolateral aspect of forearm
• goal - 30^o abduction/30^o forward flexion/30^ointernal roation
• RC is resected from prox humerus and biceps tendon tenodesed
• Articular surface of glenoid and humeral head & undesurface of acromium decorticated
• a 10 hole , 4.5mm pelvic recon plate is contoured over the spine of scapula, over acromium, and down shaft of humerus
• compression screws across GH articular suface to glenoid fossa
• plate is anchored to scapular spine w base in coracoid

Question 25

Describe the post op care after shoulder arthrodesis?

Answer 25

• Thermoplastic orthosis applied day 1 and maintained for 6 wks
• at 6 wks go to sling
• at 3/12 mobilisation exercises & thoracoscapular strengthening are commenced if no signs of loosening
• expected recovery 6-12 months

Question 26

Descibe the complications of shoulder arthrodesis

Answer 26

• Infection
• malunion
• malposition
• prominent hardwear
• humeral shaft fx