Shoulder (Complete) Flashcards
What are the intrinsic causes of shoulder pain?
[JAAOS 2015;23:492-500]
What are the extrinsic causes of shoulder pain?
[JAAOS 2015;23:492-500]
What are the advantages and disadvantages of lateral decubitus and beach chair positions for arthroscopic or open shoulder surgery?
[JAAOS 2015;23:18-28]
- Lateral Decubitus
- Advantages
- Traction increases space in the glenohumeral joint and subacromial space
- Traction accentuates labral tears
- Operating room table and/or patient’s head not in the way of posterior and superior shoulder
- Cautery bubbles move laterally out of view
- No increased risk of hypotension/bradycardia
- Better cerebral perfusion
- Disadvantages
- Nonanatomic orientation (ie, glenoid is parallel to the floor)
- Must reach around arm for anterior portal
- May need to reposition and redrape to convert to open procedure
- Not ideal for patients who cannot tolerate regional anesthesia
- Traction can cause neurovascular and soft-tissue injury
- Increased risk of injury to axillary and musculocutaneous nerves when placing anteroinferior portal
- Beach Chair
- Advantages
- Upright, anatomic position
- Ease of examination under anesthesia and ability to stabilize the scapula
- Arm not in the way of anterior portal
- No need to reposition or redrape to convert to open procedure
- Can use regional anesthesia with sedation
- Mobility of surgical arm and ability to set up arm holder to the operating room table
- Disadvantages
- Potential mechanical blocks (eg, the head) to the use of arthroscope in posterior or superior portals
- Increased risk of hypotension/bradycardia causing cardiovascular complications (ie, cerebral ischemia)
- Cautery bubbles obscure view in the subacromial space
- Fluid can fog camera if there is a leak in the attachment or in certain cameras
- Theoretically increased risk of air embolus
- Expensive equipment if using beach-chair attachment with or without mechanical arm holder
What is the normal glenoid inclination (tilt)?
[J Am Acad Orthop Surg 2015;23:317-326]
Glenoid inclination/tilt = the slope of the glenoid face in the superior-inferior direction relative to a line drawn perpendicular to the tangent of the medial scapular border
- Average of 2.2° of inferior tilt to 4.2° of superior tilt (range of -12-15.8°)
?B-angle
- Angle between glenoid face line along scapular spine
- Inclination angle is 90 - Bangle
What is the normal glenoid version?
[J Am Acad Orthop Surg 2015;23:317-326]
Glenoid version = the angle between the glenoid surface and a line drawn perpendicular to the axis of the scapular spine
- Average of 2° of retroversion (range of 12° anteversion to 14° retroversion)
What is the glenoid vault?
[J Am Acad Orthop Surg 2015;23:317-326]
It is the triangular bone extending from the glenoid articular surface to the body of the scapula (serves as the bony support for the glenoid component in shoulder arthroplasty)
How is glenoid version measured?
[The Open Orthopaedics Journal, 2017, 11, (Suppl-6, M4) 1115-1125]
Friedman method
- Friedman line drawn from the medial scapular border to the center of the glenoid on CT
- A line perpendicular to the Friedman line is drawn from the anterior edge of the glenoid
- A line drawn from the anterior to posterior edge of the glenoid
- If the posterior edge of the glenoid is anterior = anteverted
- If the posterior edge of the glenoid is posterior = retroverted
Walch classification of glenoid morphology associated with primary glenohumeral OA
[JAAOS 2012;20:604-613]
- Type A – concentric wear with no subluxation (59%)
- Subtype A1 – minor
- Subtype A2 – major
- Line connects anterior/posterior glenoid rims and transects humeral head (HH)
- Type B – posterior humeral subluxation with asymmetric wear of the posterior glenoid rim (32%)
- Subtype B1 – posterior joint space narrowing but no posterior erosion
- Subtype B2 – posterior erosion and biconcave appearance
- Subtype B3 - monoconcave, posterior wear, at least HH subluxation >70% OR retroversion >15%
- Type C – dysplastic glenoid with glenoid retroversion >25°and posterior humeral head subluxation (9%)
- Type D - Glenoid anteversion or anterior HH subluxation
What imaging modality is needed to evaluate glenoid morphology?
[JAAOS 2012;20:604-613]
CT with 3D recon – assess version, bone stock, vault anatomy
In a B2 glenoid what does each concavity represent?
[Curr Rev Musculoskelet Med. 2016 Mar; 9(1): 30–39.]
- Anterior concavity = paleo glenoid (native glenoid)
- Posterior concavity = neoglenoid
What are the complications associated with TSA from most to least frequent?
[JBJS 2017;99:256-69]
- Component loosening (glenoid > humeral)
- Glenoid wear
- Instability
- Rotator cuff tear
- Periprosthetic fracture
- Neural injury
- Infection
- Hematoma
- Deltoid injury
- VTE
What is the most common long-term complication of TSA?
[JAAOS 2015;23:317-326]
Glenoid loosening (24% of all TSA complications)
What factors contribute to glenoid loosening?
[JAAOS 2012;20:604-613]
- Altered joint reaction forces
- Component malposition
- Insufficient bony support (native glenoid)
What are the indications, absolute and relative contraindications for glenoid resurfacing in TSA?
[JAAOS 2015;23:317-326]
Indications
- Painful glenoid degeneration
- Adequate glenoid bone stock
- Intact rotator cuff
Absolute contraindications
- Active shoulder infection
- Neuroarthropathy
- Paralysis of shoulder muscles
Relative contraindications
- Age <50
- High functional demand
- Significant bone loss
- Rotator cuff dysfunction
What is the rocking horse phenomenon?
[JAAOS 2015;23:317-326]
The mechanism by which the glenoid component loosens overtime
- Occurs when the component is edge loaded causing compression on one side and distraction on the other resulting in the breakdown at the bone implant interface
What factors lead to or worsen the rocking horse phenomenon?
[JAAOS 2015;23:317-326]
- Glenohumeral instability
- Rotator cuff dysfunction
- Glenoid malposition in retroversion or superior inclination
What are revision options for glenoid component failure?
[JAAOS 2015;23:317-326]
- Component reimplantation in one or two stages
- Glenoid removal without reimplantation
- Isolated glenoid bone grafting
- Reverse TSA
What are surgical options for advanced glenoid deformity in TSA?
[JAAOS 2015;23:317-326]
- Downsizing glenoid component
- Slight undercorrection and implantation in retroversion
- Bone grafting (native osteotomized humeral head)
- Nonprosthetic resurfacing
- “ream-and-run” (ream glenoid without implanting glenoid component)
- Soft tissue interposition
- Augmented implants
- Reverse TSA
What are the principles for glenoid component implantation?
[JAAOS 2015;23:317-326]
- Adequate glenoid exposure and visualization (through soft tissue releases and optimal retractor placement)
- Recognition and correction of deformity
- Preserve bone stock and subchondral bone avoiding perforation of the glenoid vault
- Proper implant sizing
- Proper implantation of prosthesis with cement pressurization and full seating of the component in appropriate position
What are treatment options for management of glenoid retroversion and posterior glenoid bone loss in TSA?
[JBJS 2015;97:251-9][JSES (2013) 22, 1298-1308]
- <15° = Eccentric reaming
- 15-25° = augmented glenoid components
- >25° = glenoid bone grafts
- Elderly, sedentary patients = reverse TSA
What are the advantages and disadvantages of eccentric reaming for management of posterior glenoid bone loss?
[JBJS 2015;97:251-9]
Advantages
- Technically simple
- Quick
Disadvantages
- Reduction of subchondral bone
- Medialization of joint line
- Risk of poly peg cortical perforation
What are the advantages and disadvantages of glenoid bone grafts for management of posterior glenoid bone loss?
[JBJS 2015;97:251-9]
Advantages
- Improves version
- Reestablishes joint line
- Restores bone stock
Disadvantages
- Technically demanding
- Risk of nonunion
- Resorption
- Subsidence
What are the advantages of disadvantages of augmented glenoid components for posterior glenoid bone loss?
[JBJS 2015;97:251-9]
Advantages
- Improves glenoid version
- Prevents implant perforation, joint line medialization and subchondral bone loss
Disadvantages
- Technically demanding
What are the advantages and disadvantages of reverse TSA for posterior glenoid bone loss?
[JBJS 2015;97:251-9]
Advantages
- Improved constraint
- Improved fixation
What is the classification of periprosthetic humerus fractures?
[JAAOS 2008;16:199-207]
Wright and Cofield
- Type A - near the tip and extend proximally
- Type B - near the tip and extend distally
- Type C - distal to the tip
What is the management of periprosthetic humerus fractures?
[JAAOS 2008;16:199-207]
Nonoperative
- Indications
- Minimally or nondisplaced
- Stable humeral component
- Alignment maintained in fracture brace/orthosis
- Type C fractures
Operative
- Indications
- Unacceptable alignment
- Unstable humeral component
- Delayed or nonunion (consider after 3 months of nonop)
What is the management of intraoperative humerus fracture while doing shoulder arthroplaty?
[JAAOS 2008;16:199-207]
Type A and B
- Long stem prosthesis, bypass by 2-3 cortical diameters
- If cemented component already inserted perform ORIF with plate and screw/cerclage
Type C
- Long stem prosthesis if proximal enough
- ORIF with plate and screw/cerclage if too distal
What is the management of postoperative fractures?
[JAAOS 2008;16:199-207]
Type A
- Treat as loose component if length of fracture is similar to length of stem, >2mm displacement, >20° angulation
- Long stem prosthesis, bypass by 2-3 cortical diameters
- Augment with strut graft or plate
Type B
- Loose component
- Long stem prosthesis, bypass by 2-3 cortical diameters
- +/- Augment with cement in distal canal
- +/- Augment with strut graft or plate
- Long stem prosthesis, bypass by 2-3 cortical diameters
- Stable component
- ORIF with plate and screws/cerclage
Type C
- Trial of nonoperative
- Failed nonoperative
- ORIF with plate and screws/cerclage
What are the causes of anterior instability in TSA?
[JBJS 2017;99:256-69]
- Component malposition (anteversion)
- Anterior glenoid deficiency
- Surgical deltoid takedown
- Axillary nerve injury
- Failure of subscapularis repair
What are the causes of superior instability in TSA?
[JBJS 2017;99:256-69]
Rotator cuff deficiency
What are the causes of posterior instability in TSA?
[JBJS 2017;99:256-69]
- Posterior glenoid deficiency
- Component malposition (retroversion)
- Posterior capsular redundancy
What are the 4 key principles of the Grammont style rTSA?
[JSES (2015) 24, 150-160]
- The center of rotation must be fixed, distalized and medialized to the level of the glenoid surface
- The prosthesis must be inherently stable
- The lever arm of the deltoid must be effective from the start of movement
- The glenosphere must be large and the humeral cup small to create a semiconstrained articulation
Where is the center of rotation in a rTSA?
[JSES (2015) 24, 150-160]
Bone-implant interface of the glenosphere
- Maximizes compressive forces and minimizes shear forces
What are the disadvantages of medialization of the center of rotation in a rTSA?
[JSES (2015) 24, 150-160]
- Scapular notching
- Reduced ROM
- Loss of shoulder contour
What is the cause of scapular notching?
[JSES (2015) 24, 150-160]
Mechanical impingement of the superomedial humeral prosthesis against the inferior scapular neck during adduction
What strategies have been proposed to avoid scapular notching?
[JSES (2015) 24, 150-160]
- Eccentric inferior glenosphere position
- Inferior inclination of the glenoid component
- Increased lateral offset
- Decreased inclination (neck-shaft angle) of the humeral component
What are the benefits of eccentric (inferior) glenosphere placement in rTSA?
[JSES (2015) 24, 150-160]
- Decreased notching
* Inferior overhang of the glenosphere provides space between the glenosphere and scapular neck - Increased impingement-free ROM
* Creates additional clearance between the GT and coracoacromial arch
What are the advantages and disadvantages of lateral offset in rTSA?
[JSES (2015) 24, 150-160]
Advantages
- Increased ROM
- Prevents impingement between the tuberosities and the coracoid process during IR and scapular spine during ER
- Restores length-tension relationship and moment arm of subscapularis and teres minor
Disadvantages
- More stress at bone-implant interface
- Glenosphere unscrewing, baseplate loosening, migration of the glenosphere
What is the effect of increasing the humeral neck-shaft angle in rTSA?
[JSES (2015) 24, 150-160]
- Normal Grammont inclination = 155
- With increasing neck-shaft angles there is impingement between the polyethylene cup and inferior scapular neck
What is the effect of increasing the humeral retroversion in rTSA?
[JSES (2015) 24, 150-160]
- Normal Grammont retroversion = 20-40
- With increasing retroversion there is increased ER and decreased IR before impingement
The rTSA is inherently stable; however relative instability is found in what shoulder position?
[JSES (2015) 24, 150-160]
Full adduction
- Likely due to inferior impingement which results in levering effect and distractive forces
What is the effect of the rTSA on the deltoid?
[JSES (2015) 24, 150-160]
- Re-tensions the deltoid
* Effective in early abduction but loses tension and subsequent strength after 90° - Increases the moment arm (by 20-42%)
- Increases torque capacity, particularly in early abduction
- Less muscle force required to generate force
- Recruits additional fibers of the anterior and posterior deltoid
- All 3 heads demonstrate primarily abductor function (nearly all fibres are lateral to center of rotation)
- Native shoulder anterior fibres primarily flexors, middle fibres abductors and posterior fibres extensors
- Relies on rotator cuff for rotation (may be limited if torn)