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Updated: Oct 14 2023

TKA Revision

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  • summary
    • TKA Revision is most commonly performed to address aseptic loosening, fracture, instability, or infection associated with a prior TKA. 
    • Diagnosis and etiology of TKA failure can be determined by a combination of physical examination, labs, and radiographs.
    • Treatment depends on etiology of failure, prior surgery and patient activity demands. 
  • Etiology
    • Most common causes of failure
      • infection
        • should always be ruled out prior to any revision 
        • considered the most common reason for revision TKA overall based on national database epidemiology studies
        • when categorized further, infection is the most common cause of early (<2 years from primary) failure
      • aseptic component loosening
        • aseptic loosening is the second most common reason for revision TKA overall based on national database epidemiology studies
        • when categorized further, aseptic loosening is the most common cause of late (>2 years from primary) failure
        • tibial loosening more common than femoral
        • femoral loosening more difficult to detect due to obscured view of posterior femoral condyles where lesions typically occur
          • oblique radiographs may help identify
          • detected on serial radiographs
        • osteolytic wear
          • most common in uncemented technique
          •  motion between modular tibial insert and metal tray (backside wear)
      • ligament/flexion instability (~8%)
        • MCL/LCL incompetence can to lead to laxity
        • flexion instability
          • PCL attenuation (in CR knees)
          • unbalanced flexion gap
          • excessive posterior slope
          • undersized femoral component
          • femoral component placed in excessive extension
      • periprosthetic fracture (~5%)
        • most commonly supracondylar femur region
        • need for revision due to combination of excessive comminution/bone loss with loose component
      • arthrofibrosis (~5%)
      • patellofemoral maltracking
        • most commonly caused by component malpositioning
      • abnormal joint line problems
      • patellar clunk
        • fibrotic scar tissue that 'clunks' as the knee moves from flexion into extension and patella jumps the femoral notch
        • arthroscopic treatment to remove fibrotic tissue
      • metal hypersensitivity
  • Presentation
    • History
      • original etiology and indications for TKA
      • preoperative range of motion, ambulatory status
      • history of infection, thrombophlebitis, recent falls
      • history of THA
      • comorbidities
      • type of implant, review of prior records and imaging
    • Symptoms
      • temporal course is crucial:
        • pain
          • persistent since index procedure or new onset pain (may indicate potential acute vs. chronic infection)
          • pain with weight bearing indicates likely mechanical etiology
        • stiffness
        • instability
          • environment of instability (i.e. stairs, level ground, rising from chair)
    • Physical Exam
      • gait (stiff legged gait, inability to fully extend during stance phase)
      • range of motion (passive or active)
      • skin changes, presence of effusion, warmth (infection vs. complex regional pain syndrome (CRPS))
      • ligamentous exam for laxity
      • patellar tracking
  • Imaging
    • Radiographs
      • Serial AP and lateral radiographs to provide timeline of TKA
      • Weight bearing radiographs can provide evaluation of any asymmetric wear
      • Skyline view to assess patellar tracking
      • Standing leg length views to assess overall alignment
      • AP pelvis to rule out any hip pathology
    • Computed tomography
      • Femoral version study can aide in assessing component rotation when also compared to the femoral neck
      • Can also aide in assessing severity and location of bony defects
    • Bone scan
      • Can be positive for up to 2 years after primary TKA
      • Positive scan
        • nonspecific
        • can indicate loosening, infection, or stress fracture
      • Negative scan
        • rules out loosening
      • Diffuse uptake can indicate CRPS
  • Studies
    • Serum labs
      • CBC, ESR, CRP to rule out infection
    • Knee aspiration to rule out infection via cell count and culture
  • Technique - Prosthesis Selection
    • Unconstrained Posterior Cruciate Retaining
      • indicated if PCL is intact
        • always have a PCL substituting implant available as it is difficult to evaluate the integrity of the PCL prior to surgery
    • Unconstrained Posterior Cruciate Substituting
      • indicated if there is a PCL deficiency
    • Constrained Nonhinged
      • large central post substitutes for MCL/LCL function
      • indicated for varus/valgus instability
        • LCL attenuation or deficiency
        • MCL attenuation or deficiency (controversial because load may lead to breaking of central post)
        • flexion gap laxity
          • can be made stable with a tall post
    • Constrained Hinged with rotating platform
      • tibial component is allowed to do internal/external rotation within a yoke
        • reduces rotational forces that would otherwise be on prosthesis-bone interface
      • indicated for global ligament deficiency
        • LCL attenuation or deficiency
        • MCL attenuation or deficiency (deficiency of MCL is controversial because load may lead to breaking of central post)
        • flexion gap laxity with component mismatch
        • post-traumatic or multiply revised TKR
        • hyperextension instability seen in polio  
        • resection of the knee for tumor or infection
        • relatively indicated for charcot arthropathy
  • Technique - General Steps
    • Goals
      • extraction of components with minimal bone loss and destruction
      • restoration of bone deficiencies
      • restoration of joint line
      • balance knee ligaments
      • stable revision implants
      • adequate soft tissue coverage
    • General Steps
      • surgical exposure
        • should be extensile
          • when compared to the standard medial parapatellar approach for revision total knee arthroplasties, the oblique rectus snip approach shows no difference in outcomes
          • tibial tubercle osteotomy allows for good exposure and is especially indicated if there is patella baja as it allows proximal translation of the tibial tubercle
      • removal of implants
        • proceed with tibial side first by establishing tibial joint line
          • tibial joint line should be 1.5 to 2 cm above head of fibula (use xray of contralateral knee to determine exact distance)
        • after tibia joint line established proceed with femoral side to match the tibia
      • balance flexion-extension gaps
      • balance medial and lateral gaps
      • address patellofemoral tracking
        • keep patellar thickness >12mm to avoid fracture
  • Technique - Bone Defect Reconstruction
      • Anderson Orthopaedic Research Institute (AORI) Classification
      • Description
      • Treatment
      • Type 1
      • Minor bone defects with intact metaphyseal bone that do not compromise stability
      • Cement fill or impaction allograft
      • Type 2A
      • Metaphyseal bone damage that involves 1 femoral condyle or tibial plateau
      • Cement fill, augments, small bone graft
      • Type 2B
      • Metaphyseal bone damage that involves both femoral condyles or tibial plateaus
      • Cement fill, augments, small bone graft
      • Type 3
      • Massive bone loss comprising a large portion of condyle/plateau, and can involve the collateral ligaments/patellar tendon
      • Bulk allografts, custom implants, megaprosthesis, porous tantalum, metaphyseal sleeves, rotating hinge
    • Metaphyseal bone in TKR is often severely deficient due to
      • mechanical abrasion
      • extraction technique
      • infection/bone loss
    • Classification
      • Anderson Orthopaedic Research Institute (AORI) Classification
        • classification systems not used as commonly as revision THA
    • Reconstruction is addressed with:
      • long stems to promote load sharing to the femoral and tibial diaphysis
        • usually done with a long intramedullary stem
        • press-fit:
          • advantages
            • good 'scratch' fit within diaphysis
            • can help in obtaining correct alignment
            • no need for cement removal in future
          • disadvantages
            • typically no in-growth
            • increased risk of iatrogenic fracture
            • cannot use in femur with excessive bow
        • cemented:
          • advantages
            • can use in scenarios of excessive femoral bow
            • ability to delivery antbiotics
            • useful in severely osteopenic bone
          • disadvantages
            • increases complexity of any future revision
      • cavity defect filling
        • cavitary defect <1cm
          • cement is adequate for small defects, structurally better than allograft
        • cavitary defect >1cm
          • metaphyseal sleeves
            • advantages
              • encouraging mid-to-long term data
              • efficient, simple, can be used as cutting guides
              • instrumented
              • morse taper interface with implant
            • disadvantages
              • expensive
              • difficult to remove
              • specific to each implant manufacturer
              • not useful for uncontained defects
          • trabecular metal cones
            • advantages
              • short-to-mid term data encouraging
              • variety of shapes/sizes with custom shaping/contouring is possible
              • trials/specific instrumentation available
              • compatible with several different implant companies
              • can be used for uncontained defects
            • disadvantages
              • expensive
              • difficult to remove
              • cemented interface to implant
              • can be irritant to soft tissues
          • structural allograft
            • advantages
              • custom shaping available
              • satsifactory survivorship in mid-to-long term
              • potential biologic interface with host
            • disadvantages
              • time-consuming
              • disease transmission risk
              • long-term failure due to graft resorption
              • infection risk
              • technically demanding
  • Complications
    • Pain
      • pain scores less favorable than primary TKR
      • activity related pain can be expected for 6 months
    • Stiffness
    • Neurovascular problems
      • peroneal nerve subject to injury with correction of valgus and flexion deformity
    • Infection
      • upwards of 4-7%, double the risk of primary TKA
        • risk increases with MSIS grade C hosts
    • Skin necrosis
      • prior scars should be incorporated into skin incision whenever possible
      • bloody supply to anterior knee is medially based, so lateral skin edge is more hypoxic
        • if multiple previous incisions, use most lateral skin incision
      • can use wound care, skin grafting, or muscle flap coverage (gastroc) for full thickness defects
    • Extensor mechanism disruption
      • can use extensor mechanism allograft using achilles tendon bone block
        • residual lag due to attenuation is common
      • extensor mechanism reconstruction with mesh may offer better mid-term results in function and survivorship
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