Updated: 4/23/2020

Shoulder Periprosthetic Fracture

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Introduction
  • Overview
    • periprosthetic humeral shaft fractures are a relatively rare complication occurring in approximately 0.6-3% of patients that have undergone the procedure.
      • treatment typically involves ORIF or revision total shoulder arthroplasty
  • 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
    • 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
  • 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
  • Prognosis
    • high union rates when appropriately treated
      • time to union 2-8 months
    • significant decrease in shoulder ROM
Classification
 
 Wright and Cofield Classification 
Type A  • Fracture is proximal to the stem tip
Type B  • Fracture is at the level of the stem tip

Type C  • Fracture is distal to prosthetic stem top
 
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
      • placement of cable fixation 4 cm distal from latissimus dorsi insertion
 

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