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Updated: Aug 18 2024

Shoulder Periprosthetic Fracture

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  • 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
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