Introduction Replacement of humeral head and glenoid resurfacing cemented all-polyethylene glenoid resurfacing is standard of care Total shoulder arthroplasty unique from THA and TKA in that greater range of motion in the shoulder success depends on proper functioning of the soft tissues glenoid is less constrained leads to greater shear stresses and is more susceptible to mechanical loosening Factors required for success of TSA rotator cuff intact and functional if rotator cuff is deficient and proximal migration of humerus is seen on x-rays (rotator cuff arthropathy) then glenoid resurfacing is contraindicated if there is an irreparable rotator cuff deficiency then proceed with hemiarthroplasty or a reverse ball prosthesis an isolated supraspinatus tear without retraction can proceed with TSA incidence of full thickness rotator cuff tears in patients getting a TSA is 5% to 10% if positive impingement signs on exam, order a pre-operative MRI glenoid bone stock and version if glenoid is eroded down to coracoid process then glenoid resurfacing is contraindicated see Walch classification below Outcomes pain relief most predictive benefit (more predictable than hemiarthroplasty) reliable range of motion good survival at 10 years (93%) good longevity with cemented and press-fit humeral components worse results for post-capsulorrhaphy arthropathy 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 The highest degrees of glenoid erosion in B2 glenoids is typically seen between the 7- and 8-o'clock positions (posteroinferior) 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%) Indications Indications pain (anterior to posterior), especially at night, and inability to perform activities of daily living glenoid chondral wear to bone preferred over hemiarthroplasty for osteoarthritis and inflammatory arthritis posterior humeral head subluxation Contraindications insufficient glenoid bone stock rotator cuff arthropathy deltoid dysfunction irreparable rotator cuff (hemiarthroplasty or reverse total shoulder are preferable) risk of loosening of the glenoid prosthesis is high ("rocking horse" phenomenon) active infection brachial plexus palsy Preoperative Imaging Radiographs true AP determine extent of arthritis and look for superior migration of humerus axillary view look for posterior wear of glenoid CT scan obtain CT scan to determine glenoid version and glenoid bone stock MRI evaluate rotator cuff condition Approach Deltopectoral detach the subscapularis and capsule from anterior humerus dislocate shoulder anteriorly tight shoulders may require release of the upper half of the pectoralis tendon to increase exposure and dislocation pectoralis major tendon passes on top of the biceps tendon to attach to the humerus Complications axillary nerve damage is the most common complication axillary nerve and posterior humeral circumflex artery pass beneath the glenohumeral joint in the quadrilateral space Technical considerations Capsule anterior capsule contracture (passive ER < 40°) treatment anterior release and Z-lengthening posterior capsule stretching treatment volume-reducing procedure (plication of posterior capsule) Subscapularis no differences in outcomes between subscapularis peel, lesser tuberosity osteotomy, subscapularis tenotomy, partial tenotomy Glenoid deficiency and retroversion glenoid deficiency treatment build up with iliac crest autograft or part of the resected humerus do not use cement to build up the deficiency retroverted glenoid treatment build up posterior glenoid with allograft eccentrically ream anterior glenoid Glenoid component convex backside superior to flat recreate neutral version peg design is biomechanically superior to keel design polyethylene-backed components superior to metal-backed components glenoid not large enough to accommodate both metal and PE uncemented glenoid has a lower rate of loosening conforming vs. nonconforming both have advantages and neither is superior conforming is more stable but leads to rim stress and radiolucencies nonconforming leads to increased polyethylene wear Humeral stem fixation cemented stem or uncemented porous-coated implants position of humeral stem should be 25-45° of retroversion if position of glenoid retroversion is required, then the humeral stem should be less retroverted to avoid posterior dislocation avoid valgus positioning of humeral stem avoid overstuffing the humeral head increases joint reaction forces and tension on the rotator cuff the top of the humeral head should be 5 to 8 mm superior to the top of the greater tuberosity intraoperative humerus fracture greater tuberosity fracture treatment if minimally displaced, insert a standard humeral prosthesis with suture fixation and autogenous cancellous bone grafting of the greater tuberosity fracture humeral shaft fracture treatment remove prosthesis and add longer stem with cement and reinforce with cerclage wiring Rehabilitation Passive or active-assisted motion only during early rehab limiting factor in early postoperative rehabilitation is risk of injury to the subscapularis tendon repair Progress to ER isometrics Limit passive external rotation risk of tear and pull-off of subscapularis tendon from anterior humerus tear leads to anterior shoulder instability (most common form of instability after TSA) treatment of subscapularis pull-off is early exploration and repair of tendon test for pull-off of subscapularis weak belly-press test inability to put hand in back pants pockets or tuck shirt behind the back avoid pushing out of chair during acute rehab IR eccentric and isometric Complications Glenoid loosening most common cause of TSA failure (30% of primary OA revisions) risk factors insufficient glenoid bone stock (posterior glenoid wear associated with glenoid loosening) rotator cuff deficiency 2.9% reoperation rate for loosening (28% with revision) radiographic lines presence of radiographic lines does not correlate with symptoms progression of a radiographic line does correlate with symptoms progression present in 50% of patients as early as 3 to 4 years after TSA radiolucency around the glenoid does not always correlate with clinical failure at 3- and 7-year follow-up did not correlate with poor functional outcomes or pain Vascular injury Arcuate artery, branch off the anterior humeral circumflex artery, can be damaged during biceps tendon elevation Humeral stem loosening more common in RA and osteonecrosis rule out infection Subscapularis repair failure Malposition of components Improper soft tissue balancing failure due to undiagnosed presence of rotator cuff tears Iatrogenic rotator cuff injury/attritional rotator cuff tear can occur if humeral neck osteotomy is inferior to level of rotator cuff insertion overstuffing glenohumeral joint leading to attritional supraspinatus and subscapularis tears common reason for conversion to reverse total shoulder arthroplasty Stiffness Infection may have normal aspiration results culture arthroscopic tissue culture more sensitive (100% sensitive and specific) than fluoroscopically guided aspiration (17% sensitivity, 100% specific) Propionibacterium acnes (P. acnes), now referred to as Cutibacterium acnes (c. acnes) most common cause of indolent infections and implant failures infection rate 1-2% after primary TSA characteristics gram positive, facultative, aerotolerant, anaerobic rod that ferments lactose to propionic acid has high bacterial burden around the shoulder forms biofilm within 18-90h (found on implant surface and on synovial tissue) >> planktonic (explains why aspiration is only 17% sensitive) P. acnes PJI more common in males presentation initial pain & stiffness later swelling & redness diagnosis use anaerobic culture bottles, keep for 10-14days (mean time to detection 6 days) 16s rRNA PCR imaging (XR, CT, ultrasound) positive for subluxation/loosening in 24% of cases if implant is removed, sonicate implant (to dislodge bacteria from surface) for sonication culture treatment early infection (<6 weeks) can be treated with open irrigation and debridement late infection (>6 weeks) should be treated by explant and 2-stage reimplantation after IV antibiotic (penicillin G, ceftriaxone, clindamycin, vanco) x 6wk, followed by 2-6mths of PO antibiotic Neurologic injury axillary nerve is most commonly injured inferior border of subscapularis tendon can be used as a landmark to identify axillary nerve as it courses from anterior to posterior musculocutaneous nerve can be injured by retractor placement under conjoint tendon Periprosthetic fracture acceptable fragment alignment ≤ 20° flexion/extension, ≤ 30° varus/valgus, ≤ 20° rotation malalignment see table below Wright & Cofield Classification of Periprosthetic fracture Type Characteristics Treatment of Intraoperative Fracture Treatment of Postop Fracture Type A Centered near the tip of the stem and extends proximally Span fracture with standard length prosthesis (2-3 cortical diameters) or long-stem prosthesis. Transosseous sutures for tuberosity fractures Usually min displaced/angulated (treat nonop). If significant overlap between prox-distal fragments, treat as if stem loose and revise to long stem prosthesis. Type B Centered at the tip of the stem and extends distally. Span fracture with standard length prosthesis (2-3 cortical diameters) or long-stem prosthesis. Cement in distal canal to engage prosthesis (do NOT let cement escape from fracture site). Cortical strut allograft + cerclage. Revise to long-stem prosthesis. Cement in distal canal to engage prosthesis Type C Located distal to the tip of the stem. Long-stem prosthesis, or if close to olecranon fossa, plate+screws± cerclage wire, strut allograft ORIF (plate overlap prosthesis by 2 cortical diameters to avoid stress riser)