summary Shoulder Periprosthetic Fractures are intraoperative or postoperative complications associated with shoulder arthroplasty that can lead to loosening and migration of the prosthesis. Diagnosis can be made with plain radiographs of the shoulder and humerus. CT scan can help identify loosening of the prosthesis. Treatment involves ORIF or revision shoulder arthroplasty depending on location of the fracture and stability of the prosthesis. Epidemiology Incidence 0.6-3% of patients with TSA Demographics typically occurs in patients 50-85 years of age Timing of onset most fractures often occur intraoperative at the time of the original implant consists of 20% of all complications Anatomic location adjacent to the prosthetic stem tip greater tuberosity most commonly occurs during revision total shoulder arthroplasty Risk factors soft tissue contractures osteoporosis endosteal notching aggressive reaming incorrect entry reaming site ideal entry reaming site is 9 mm lateral from anatomic center of rotation use of press fit humeral stems compared to cemented stems revision arthroplasty cases history of instability female sex post-traumatic arthritis increased comorbidity index osteonecrosis corticosteroid-induced > alcohol and post-traumatic Etiology Pathophysiology intraoperative fractures occur most often during revision total shoulder arthroplasty greater exposure required during these procedures increased scarring in the subacromial space and around the rotator cuff increased soft-tissue retraction and greater torque placed on humerus removing previous implant (up to 81% of intraoperative fractures) metaphyseal filling implants -> increased risk of greater tuberosity fractures bone loss from cement removal bone loss from disengagement of the bone-implant interface diaphyseal-engaging stems -> greater tuberosity fractures stress shielding of the metaphysis methods to prevent: clearing soft-tissue from lateral portion of implant use of implant specific removal instruments controlled corticotomy other mechanisms of intraoperative fractures: reaming or broaching (up to 31% of intraoperative fracture) implant trialing or insertion (up to 19% of cases) during exposure (up to 15% of cases) forceful retractor placement primary total shoulder arthroplasty has a lower risk for intraoperative fracture factors associated with primary intraoperative fractures endosteal notching from reaming excessive humeral external rotation during exposure cortical breaching during reaming or broaching especially in ostepenic bone post-operative fractures can occur as a result of a fall or fatigue fracture through a stress riser fall on outstretched hand tip of prosthesis acts as a stress riser most postoperative fractrues as a result occur at or adjacent the tip of the prosthesis stem atraumatic due to prosthetic loosening cortical weakening from implant "rattling" inside medullary canal high risk of nonunion prosthesis disrupts endosteal blood supply impairing fracture revascularization and healing prosthetic stem distracts the two fragments preventing end-to-end healing Associated conditions nonunion osteoporosis RA female sex displacement >2 mm presence of cement at fracture site Classification Wright and Cofield Classification Type A Fracture centered near the tip of the stem and extends proximally Type B Fracture centered near the tip of the stem and extends distally Type C Fracture located distal to the tip of the stem. Presentation History mechanical fall fall on out-stretched hand worsening arm pain present with mechanical loosening of the prosthesis Symptoms common symptoms acute pain in the upper arm prodromal pain maybe present in patients with mechanically loose implants gross deformity Physical exam inspection varus or valgus deformity ecchymosis & swelling shortening of the affected arm diffuse tenderness of the upper arm motion patient may not be able to move affected elbow or shoulder most often due to pain neurovascular examine for radial nerve status high incidence of radial nerve palsy with distal humerus fractures most often neurapraxia and does not require operative management document full neurological and vascular findings Imaging Radiographs orthogonal radiographs of the affected humerus AP, axillary lateral, Grashey, scapular Y views findings fracture involving the prosthetic stem tip usually in an oblique pattern criteria dictating treatment appearance of stem stability zones of lucency around stem suggests lack of bone ingrowth or osteolysis CT indications concern for loose prosthesis fracture pattern on radiographs concerning for mechanical stability of humeral stem prodromal pain consistent with mechanical loosening comminution perform with metal suppression protocol decreased artifact from prosthesis assessment: determine fracture morphology assess remaining bone stock quality of the rotator cuff muscle version of the glenoid if revision is determined necessary Treatments Nonnoperative treatment immobilization indications long oblique or spiral type A or B fractures with a stable prosthesis type C fracture outcomes: union rates <50% Operative treatment conversion to prosthetic stem spanning fracture site by two cortical diameters indications intraoperative type A fractures conversion to proximally porous coated long stem prosethesis spanning fracture site by two to three cortical diameters indications intraoperative type B fractures intraoperative type C fractures open reduction and internal fixation indications intraoperative fractures type C unamenable to long stem prosthesis postoperative fractures transverse type A and B fractures with stable prosthesis type C that has failed nonsurgical management patients unable to tolerate nonoperative management revision arthroplasty with supplementary fixation indications presence of a loose prosthesis with any fracture type long stem prosthesis poor bone stock bypass fracture by two cortical diameters short stem prosthesis good bone stock convert to a shorter stem prosethesis than original and apply supplementary fixation Techniques Immobilization coaptation splint followed by functional bracing hydrostatic pressure created by brace stabilizes fracture site higher risk of nonunion with type A and B fractures Conversion to prosthetic stem spanning fracture site by two cortical diameters removal or original stem placement of longer stem engages distal fragment and improves fracture alignment +/- supplementary fixation depending on fracture stability Conversion to proximally porous coated long stem prosethesis spanning fracture site by two to three cortical diameters proximal porous coating allows for metaphyseal stability distal fragment cemented to stem tip techniques: pack cement into the distal canal to allow for distal stem fixation avoid proximal cement extrusion into fracture site use cortical strut grafting with cerclage cables in cases of bone deficiency olecranon fossa may prevent successful treatment with this method Open reduction and internal fixation techniques: approaches: anterolateral approach to the humerus can be extended from deltopectoral approach used for the index procedure tip of coracoid process curve along the deltopectoral groove continue incision along lateral border of biceps brachii develop interval between biceps and brachialis muscle divide brachialis muscle longitudinally at midline and elevate subperiosteally to expose distal aspect humerus medial fibers innervated by musculocutaneous nerve lateral fibers innervated by radial nerve preserve as much soft tissue attachment to the humerus as possible place appropriate sized plate usually 4.5 mm LC-DCP plate screw fixation distal to stem cerclage cables proximal to stem tip posterolateral approach good for distal postoperative fracture with stable prosthesis greater tuberosity and calcar fractures suture or cable fixation hydbrid locking plates with cerclage cables have been used for postoperative fractures plate placed eccentrically on humerus to allow locking screws to miss humeral stem allows bicortical fixation around the stem use of cerclage cables for added stability alternatively can use dual plate constuct or 3.5 mm attachment plates for bicortical fixation can combine with allograft augmentation for fractures with deficient cortices can use cortical strut allograft and fix with cerclage cables 2 hemicylinders can be used to form a sarcophagus around prosthesis Revision arthroplasty with supplementary fixation type of revision prosethesis is dependent on the quality of bone stock poor bone stock conversion to long-stemmed prosthesis bypasses fracture site by at least two to three cortical diameters can be augmented with allograft to enhance bone stock good bone stock conversion to short-stemmed prosthesis stem ends more proximal than original prosthesis apply supplementary fixation to fracture site shorter stem impants prevents stem tip from distacting the fracture site Complications Nonunion Delayed union Glenohumeral stiffness Radial nerve injury can be secondary from the fracture iatrogenic from fixation with cerclage cables instrumentation proximal to the inferior edge of the latissimus dorsi insertion may reduce the risk of iatrogenic radial nerve injury Prognosis High union rates when appropriately treated time to union 2-8 months Significant decrease in shoulder ROM