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Shay Hartman's > Knee Arthroplasty (Complete) > Flashcards

Knee Arthroplasty (Complete) Flashcards

1
Q

Describe the 4th generation cementing technique

A
  1. Vacuum mixing cement (reduces porosity, increases fatigue strength)
  2. Medullary plug/cement restrictor (limits the cement column)
  3. Clean dry bone (increases cement interdigitation)
  4. Retrograde insertion of cement (reduces blood lamination)
  5. Cement pressurization (increases cement interdigitation)
  6. Prosthesis centralizers (even cement mantle)
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2
Q

What are the important anatomic/mechanical measurements in TKA?

A
  1. Mechanical axis of the limb
    * Line from the centre of the femoral head to the centre of the ankle joint
  2. Anatomical axis of the femur
    * Line that bisects the femur medullary canal
  3. Mechanical axis of the femur
    * Line from the centre of the femoral head to the intersection of the anatomical axis and the intercondylar notch
  4. Distal femoral cut angle
  • 5-7 degrees of valgus
  • Difference between the mechanical and anatomical axis
  1. Anatomical axis of the tibia
    * Line that bisects the tibia medullary canal
  2. Mechanical axis of the tibia
    * Line from the centre of the proximal tibia to the centre of the ankle
  3. Proximal tibial cut angle
  • 0 degrees of varus/valgus
  • 90 degrees to the mechanical axis of the tibia
  1. Normal tibial slope = 10+/-3 degrees
  2. Normal tibia plateau relative to the mechanical axis = 87° of varus (MPTA)
  3. Normal distal femur relative to the anatomical axis = 81° of valgus (aLDFA)
  4. Normal distal femur relative to the mechanical axis = 87° of valgus (mLDFA)
  5. Posterior condylar axis
  • Line connecting the apex of the posterior aspect of the medial and lateral femoral condyles with the knee in flexion
  • 3 degrees internally rotated relative to the transepicondylar axis
  1. Whitesides line
    * Line extending from the deepest point of the femoral trochlea to the centre of the intercondylar notch
  2. Transepicondylar axis
    * •Line extending between the medial and lateral epicondyles
  3. Q angle
  • Angle formed between a line drawn from the ASIS to the centre of the patella and a line from the centre of the patella to the tibial tubercle
  • Females = 18, males = 14

16.Tibiofemoral angle

  • Angle formed between the anatomical axis of the femur and tibia
  • Normal = ~6 degrees
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3
Q

What are the technical goals in TKA?

A
  1. Restore neutral mechanical alignment of limb
  2. Restore joint line
  3. Balance ligaments
  4. Well tracking patella
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4
Q

What is the difference between mechanical alignment and kinematic alignment?

A

1.Mechanical alignment

  • A. Avoids tibia cut in anatomical varus (3°)
  • B. Tibia cut is perpendicular to the mechanical axis (90° to the anatomical axis)
  • C. Femoral cut is perpendicular to the mechanical axis (4-6° valgus to the anatomical axis)

2.Kinematic alignment

  • A. AKA: Anatomic alignment, constitutional alignment
  • B. Compared to mechanical alignment
    • Femoral cuts are in 2-4° more valgus
    • Tibial cuts are in 2-4° more varus
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5
Q

What is the difference between measured resection vs. gap balancing?

A

1.Measured resection

  • A. Relies on transepicondylar axis, Whitesides line, posterior condylar axis
  • B. Utilizes anterior or posterior referencing guides
    • Anterior referencing avoids notching but can lead to overresection of posterior condyles increasing the flexion gap
    • Posterior referencing can lead to anterior notching
  • C. Disadvantage = variable femoral anatomy
    • E.g. hypoplastic lateral femoral condyle

2.Gap balancing

  • A. Relies on a precise tibial cut 90° to the mechanical axis
    • The gaps are then balanced by removing osteophytes and tension is held with distraction devices
    • Femoral cuts are made parallel to the tibial cut in flexion and extension
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6
Q

What are the levels of mechanical restraint in TKA design?

A

1.Least constrained

  • Cruciate retaining (CR)
    • PROS
      • Bone conserving
      • More consistent joint line restoration (small flexion gap)
      • More proprioceptive feedback with PCL
    • CONS
      • Harder to balance in severe deformities
      • Tight PCL in flexion causes PE wear
      • Late rupture/stretch of PCL leading to instability
      • Sliding PE wear due to paradoxical forward sliding
  • Cruciate sacrificing
    • Posterior stabilized = polyethylene post and cam
      • Indications:
        • PCL deficient knee, patellectomy, inflammatory arthritis
    • PROS
      • Easier to balance soft tissues
    • CONS
      • Femoral cam jump
      • Patella clunk syndrome
      • Tibial post wear and breakage
      • Not bone conserving (intercondylar notch punch removes more bone)
      • Larger flexion gap (leads to elevation of joint line due to larger distal femoral resection)
    • oAnterior stabilized = extended anterior PE lip
      1. Constrained
  • Constrained non-hinged (high tibial post) [aka. varus valgus constrained, condylar constrained]
    • CONS
      • Increased polyethylene wear
      • Higher rate of aseptic loosening (greater forces through implant-bone interface)
    • PROS
      • Substitutes for MCL or LCL deficiency
        3. Most constrained
  • Hinged with rotating tibial platform
    • Indications [CORR 2010 May; 468(5): 1248–1253]
      • Global ligamentous instability
      • Severe deformity (with associated soft tissue releases)
      • Severe bone loss (with loss of ligamentous attachments)
      • Gross flexion extension imbalances/mismatch
      • Hyperextension instability (eg. polio)
      • Limb salvage surgery in oncology
      • Comminuted or nonunited distal femur fracture in elderly
      • Ankylosis with instability following releases
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7
Q

What are the advantages/disadvantages of using a subvastus/midvastus approach to the knee?

A
  1. Advantages [AAOS comprehensive review 2, 2014]
  • VMO insertion into medial quads tendon and patella not disrupted
  • Accelerated rehabilitation (due to rapid restoration of quadriceps function)
  • Patellar tracking may be improved (less lateral release needed)
  1. Relative contraindications [AAOS comprehensive review 2, 2014]
  • Obesity
  • Preoperative stiffness
  • Previous HTO
  • Revision TKA
  • Extremely muscular quads
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8
Q

What is the consequence of a flexion contracture post-TKA?

[JBJS(B) 2012;94-B, Supple A:112–15]

A
  1. Increased energy expenditure as a result of quadriceps activity to prevent knee buckling
  2. Relative LLD
    * Shortens stride length, increases contralateral knee forces, alters trunk alignment
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9
Q

What is the intraop management of flexion contractures in TKA?

[JBJS(B) 2012;94-B, Supple A:112–15]

A
  1. Remove posterior osteophytes
  2. Release posterior capsule (off femur and tibia)
  3. Additional distal femoral resection
    * Generally, take an additional 2mm for flexion contractures >10°
  4. Decrease tibial slope
  5. Avoid implanting components in flexion
  6. PS knee preferred
  7. PCL recession in CR knees
    * Release from posterior tibia, medial femoral condyle or V-shaped osteotomy of the posterior tibia
  8. Release medial and lateral gastrocnemius
  9. Post operative splinting, CPM, shoe lift on contralateral side (forces extension), exercises, close followup
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10
Q

What are causes of patellar maltracking in TKA?

[JAAOS 2016;24: 220-230]

A
  1. Internally rotated femoral component
  2. Medialized femoral component
  3. Internally rotated tibial component
  4. Medialized tibial component
  5. Lateralized patellar button
  6. Valgus deformity (must restore neutral mechanical axis)
    * I.e. >7° valgus positioning of the femoral component
  7. Overstuffing patellofemoral joint
    * I.e. Increased net patella thickness (increases tension on lateral retinaculum thereby increasing lateral patellar pull)
  8. Asymmetric patellar resection
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11
Q

What are the intraop treatment options for patellar maltracking in TKA?

A
  1. Take down tourniqette to confirm maltracking
  • “No thumb” test – patella should track with its medial edge in contact with the medial femoral component with the medial capsule open throughout the range without the surgeon keeping it in position
  • “Kissing rule” – in maximal flexion the medial surface of the patella should make contact with the medial condyle of the femoral component
  1. Lateral release
  2. Medial plication
  3. Tibial tubercle osteotomy
  4. Quadsplasty
  5. Component revision
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12
Q

What is the technique for performing a lateral release of the patella?

A
  1. Option 1 [Clin Orthop Relat Res (2012) 470:2854–2863]
  • Progress to the next step only if needed
  • Step 3 sacrifices the superior lateral geniculate artery
  • STEPS:
    • Step 1 - Release of distal part
      • Release of the lateral retinaculum starting from the midlevel of the patella, progressing distally to the upper tibial border
    • Step 2 - Partial release of proximal part
      • Release of the lateral retinaculum starting from midlevel of the patella, progressing proximally up to the proximal border of the patella;
      • The lateral superior genicular artery is preserved
    • Step 3 - Complete release of proximal part
      • Further release of the retinaculum from the superior border of the patella, progressing proximally, lateral to the vastus lateralis, for approximately 2 to 4 cm
      • This includes release of the superior geniculate artery
        2. Option 2 [The Journal of Arthroplasty Vol. 24 No. 5 2009]
  • Progress to the next stage only if needed
  • Release of the lateral patellofemoral ligament from within the joint
  • Outside staged retinacular release preserving the deep capsulosynovial layer
  • STEPS:
    • Stage 1 - Release of the LPFL from the deep aspect
    • Stage 2 - Release of the lateral retinaculum starts 25 mm proximal to the patella, down to the level of the superior border of the patella, and 20 mm lateral to it
    • Stage 3 - Release of the lateral retinaculum down to the level of the midpatella
    • Stage 4 - Release of the lateral retinaculum down to the distal pole of the patella
    • Stage 5 - Lateral release from the inferior border of the patella to the level of the knee joint line
    • Stage 6 - Lateral release down to the level of the Gerdy tubercle
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13
Q

How do you assess patellar height?

A
  1. Blumensaat’s line
    * Should extend to the inferior pole of the patella in 30 degrees of flexion
  2. Insall-Salvati Method/Ratio/Index
  • Ratio of the length of patellar tendon to the length of the patella (ideally in 30 degrees of knee flexion)
  • Normal = 0.8-1.2
  • Patella baja = <0.8
  • Patella alta = >1.2
  1. Caton Deschamps method
  • Defined by the ratio between the articular facet length of the patella and the distance between the inferior articular facet of the patella and the anterior corner of the superior tibial epiphysis
  • Normal = 0.6-1.3
  1. Blackburne-Peel method
  • Ratio between a line drawn from the inferior articular facet of the patella to a horizontal parallel to the tibial plateau and the patellar articular facet length
  • Normal = 0.8-1.0
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14
Q

What is the treatment of patella baja in TKA?

A
  1. Lower joint line
    * Resect more tibia, resect less distal femur (or augment)
  2. Place patella poly superiorly and trim distal patellar pole
  3. Tibial tubercle osteotomy moving it cephalad
  4. Patellectomy
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15
Q

What are 4 acquired causes of patella baja?

A
  1. HTO
  2. TTO
  3. Trauma (scarring)
  4. Raising the joint line in TKA
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16
Q

A valgus knee is generally defined as a tibiofemoral angle greater than what?

A

Tibiofemoral angle >10 degrees

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17
Q

Which approach is most commonly used in a valgus TKA?

A
  • Medial parapatellar approach is sufficient in most cases
  • Lateral parapatellar approach is described:
    • Pros:
      • Direct access to lateral structures
      • No disruption of medial patella blood supply
    • Cons:
      • Limits access to central and medial structures
      • Lack of soft tissue for closure
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18
Q

What are 3 factors to consider in valgus TKA and ways to address them?

A
  1. Contracted lateral soft tissue structures
  • Structures that may require release:
    • Lateral osteophytes (may bowstring lateral structures)
    • Posterolateral capsule and arcuate ligament (extends from fibula head to posterolateral capsule)
    • Iliotibial band [release mainly affects extension gap]
    • Popliteus tendon [release mainly affects flexion gap]
    • LCL
    • Lateral head of gastrocnemius
    • Biceps femoris tendon (rare to release)
    • PCL if tight laterally in flexion
  • Typically sufficient release is achieved with release of posterolateral capsule and ‘pie-crusting’ of lateral structures
    • More severe deformities may require release of LCL and popliteus from lateral epicondyle and lateral head of gastroc from femoral insertion
      1. Lax medial structures
  • Tightening medial structures is usually achieved by ‘filling up’ the medial side (requires thicker poly) and release of lateral structures
  • Occasionally the MCL is tightened by MCL advancement, MCL division and imbrication or recessing the origin of the MCL with a bone block
  1. Lateral bone loss
  • Hypoplastic or deficient lateral femoral condyle may require augments
  • Lateral tibial bone loss can be addressed by increasing the cement mantle or resecting more tibia to allow rim contact
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19
Q

What are 3 factors to consider in a varus knee and how to correct them?

A
  1. Contracted medial soft tissue structures
  • Structures that may require release
    • Osteophytes (cause bowstringing of medial soft tissue)
    • Capsule
    • Superficial MCL
      • Release of anterior fibres mainly affects flexion gap
      • Release of posterior fibres mainly affects extension gap
    • Posterior oblique ligament fibres of MCL
      • Release affects mainly extension gap
    • Semimembranosus
      • Release affects mainly extension gap
    • Pes anserinus
      • Release affects mainly extension gap
    • PCL
      • Release affects mainly the flexion gap
  • Consider resection bone from the medial aspect of the medial tibial plateau and lateralizing the tibial component
    2. Lax lateral structures
  • Tightening lateral structures is usually achieved by ‘filling up’ the lateral side (requires thicker poly) and release of medial structures
  • Occasionally the LCL is tightened by LCL advancement
  1. Medial bone loss
    * Consider augments, cement, allogaft bone/synthetic
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20
Q

What are the indications for high tibial osteotomy?

A
  1. Pain located primarily on the medial aspect of the knee
  2. Medial compartment OA (less than 4mm of medial joint space on standing radiograph)
  3. Varus knee deformity
  4. Young patient undergoing articular cartilage restoration or medial meniscus transplant
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21
Q

What are the contraindications for HTO?

A
  1. Less than 90 degrees of flexion
  2. Flexion contracture >10-15 degrees
  3. Severe medial compartment articular damage (Ahlback grade III or higher)
  4. Patellofemoral OA (symptomatic)
  5. Lateral compartment OA
  6. Prior lateral meniscectomy
  7. Inflammatory arthritis
  8. Ligament instability (especially varus thrust gait)
  9. Lateral tibial subluxation >1 cm
  10. Obesity (relative)
  11. Smoking (relative)
  12. Age >65 (relative)
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22
Q
A
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23
Q

What are the complications of HTO?

[JAAOS 2011;19:590-599]

A
  1. Undercorrection/overcorrection
  2. Loss of correction
  3. Patella baja
  4. Nonunion/malunion
  5. Peroneal nerve palsy
  6. Compartment syndrome
  7. Infection
  8. DVT/PE
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24
Q

What are the advantages and disadvantages of closing wedge HTOs?

[Knee Surg 2017;30:409–420] [Sports Med Arthrosc Rev 2013;21:38–46)]

A

Advantages

  • Inherently stable
  • Less nonunion
  • No bone graft required
  • May allow earlier WB

Disadvantages

  • Requires fibular osteotomy or proximal tib-fib joint disruption
  • Risk of common peroneal nerve injury
  • Loss of bone stock
  • Less predictable in achieving desired correction (no gradual correction)
  • Change in offset of the upper tibial metaphysis may affect future TKA
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25
Q

What are the advantages and disadvantages of opening wedge HTOs?

[Knee Surg 2017;30:409–420] [Sports Med Arthrosc Rev 2013;21:38–46)]

A

Advantages

  • Avoids fibular osteotomy
  • Less risk to common peroneal nerve
  • Allows for gradual correction
  • Allows for correction of tibial slope
  • May be easier to convert to TKA
  • Bone preserving
  • Can perform combined ACL recon without need for additional incisions

Disadvantages

  • Inherently unstable
  • Loss of correction
  • Risk of nonunion/malunion
  • Risk of fracture of the lateral tibial plateau or cortex
  • Requires bone graft
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26
Q

What is the normal medial proximal tibial angle?

[Rockwood and Green 8th ed. 2015]

A

87o (ie. 3o of varus)

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27
Q

When is an increase or decrease in tibial slope desirable in HTO?

[JAAOS 2011;19:590-599]

A
  1. Increased tibial slope = PCL deficiency
  2. Decreased tibial slope = ACL deficiency
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28
Q

Where is the lateral hinge located for the osteotomy (HTO)?

[JAAOS 2011;19:590-599]

A

1cm distal to the joint line and 1cm medial to the lateral cortex

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29
Q

Describe the preoperative planning and determination of correction in HTO?

[JAAOS 2011;19:590-599]

A
  1. 62.5% = Fujisawa point (considered the optimal location for the mechanical axis)
  • Corrects to 3-5 degrees valgus
  • Line from center of femoral head and line from center of the ankle pass through Fujisawa point
  1. Line a-b = proposed osteotomy from 4cm distal to joint line medial and to tip of fibula laterally
  2. Alpha = angle of correction
  3. b1-c = gap in mm for correction
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30
Q

What are the technical challenges of TKA after HTO?

[AAOS comprehensive review 2, 2014]

A
  1. Previous incisions
  2. Hardware
  3. Patella baja (difficult exposure)
  4. Tibial abnormalities (metaphyseal offset after closing wedge osteotomy)
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31
Q

What is the normal distal femoral valgus angle?

[JAAOS 2018;26:313-324]

A

7-9° valgus

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32
Q

What are the indications for a varus producing distal femoral osteotomy?

[Arthroscopy Techniques 2016: 5(6); e1357-e1366]

A
  1. Genu valgus alignment
  2. Isolated lateral compartment OA
  3. Chondral or osteochondral lesions of the lateral compartment
  4. Meniscal deficiency of the lateral compartment
  5. Cartilage repair/restoration of the lateral compartment
  6. Chronic MCL or cruciate instability
  7. Refractory patellar instability
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33
Q

What are the contraindications for a varus producing DFO?

[Arthroscopy Techniques 2016: 5(6); e1357-e1366] [JAAOS 2018;26:313-324]

A
  1. Inflammatory OA
  2. Medial or patellofemoral OA
  3. Flexion contracture >15°
  4. Flexion <90°
  5. Deformity >15°
  6. Tibial subluxation
  7. Gross knee instability
  8. Severe lateral compartment bone loss
  9. Nicotine use (relative)
  10. Obesity (relative)
  11. Age >50 (relative)
  12. History of septic arthritis (relative)
  13. Inability to comply with postoperative instructions
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34
Q

In general, what is the cause of the valgus knee deformity in OA?

[Arthroscopy Techniques 2016: 5(6); e1357-e1366][JAAOS 2018;26:313-324]

A
  1. Hypoplastic lateral femoral condyle
    * Femoral osteotomy avoids an oblique joint line (which would occur if the valgus was addressed through a HTO)
  2. Valgus secondary to proximal tibia deformity (less common)
  • Eg. tibial fracture malunion
  • Consider proximal tibia varus osteotomy
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35
Q

What are the advantages and disadvantages of a DFVO over arthroplasty in younger patients?

[JAAOS 2018;26:313-324]

A

Advantages

  • Native joint preservation
  • Unrestricted high impact activity after union
  • Possible delay of future arthroplasty

Disadvantages

  • Longer rehabilitation
  • Early WB restrictions
  • More variation in pain relief
  • Conversion to TKA more technically challenging
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36
Q

What are the advantages of a medial closing wedge vs. a lateral opening wedge DFO?

[Arthroscopy Techniques 2016: 5(6); e1357-e1366] [JAAOS 2018;26:313-324]

A
  1. Medial closing wedge
  • Direct bone contact leads to increased stability
  • Reliable bone healing
  • No bone graft
  • Less hardware irritation
  1. Lateral opening wedge
  • More precise adjustment of correction
  • Single osteotomy
  • Familiar lateral approach
  • Access to the lateral compartment for concomitant procedures
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37
Q

What are the indications for a medial closing wedge over a lateral opening wedge osteotomy?

[JAAOS 2018;26:313-324]

A
  1. Angle of correction >17.5°
  2. Operated limb exhibits a limb length discrepancy
  3. Earlier WB desired
  4. Risk factors for delayed union (eg. smoking, neuropathy, poor bone quality, obesity)
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38
Q

What should a patient be counselled on prior to osteotomy for unicompartmental OA?

[Sports Med Arthrosc Rev 2013;21:38–46)]

A
  1. Some degree of continued pain
    * The pain is accepted in exchange for higher activity levels and avoidance of prosthetic implant failure
  2. Conversion to arthroplasty in the future is not a failure but rather an anticipated event
  • Survival rates are ~95% at 5 years, 80% at 10 years and 55% at 15 years
  • Outcomes of TKA after osteotomy are equivalent
  1. Cosmetic changes to limb alignment
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39
Q

How is the correction angle calculated for a DFO?

[Arthroscopy Techniques 2016: 5(6); e1357-e1366]

A
  1. Goal is a neutral mechanical axis (mechanical axis passes through or just medial to the center of the knee)
  • Lateral compartment OA consider correction 62.5% of the way to the medial compartment
  • Other indications are typically through the center of the knee
  1. Correction angle = angle formed between the mechanical axis of the femur (center of head of femur and selected point) and mechanical axis of tibia (center of the talus and selected point)
  2. Confirm the deformity is femoral based
  • Calculate the medial-proximal tibial angle (average = 87)
    • Should be normal if DFO planned
  • Calculate the lateral-distal femoral angle (average = 87)
    • Should be decreased if DFO planned
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40
Q

What is the postoperative management following DFVO?

[JAAOS 2018;26:313-324]

A
  1. 6 weeks nonWB (allow ROM)
  2. 6-12 weeks graduated WB
  3. 12 weeks start low impact/light duties
  4. 6 months resume high impact/full duties
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41
Q

What are the complications of a DFVO?

[JAAOS 2018;26:313-324]

A
  1. Distal femoral fracture
  2. Nonunion/malunion
  3. Neurovascular injury
  4. Infection
  5. Thromboembolic event
  6. Stiffness
  7. Painful hardware
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42
Q

What is the definition of supracondylar periprosthetic (TKA) fracture?

A

Within 15cm of the joint line or, in the case of a stemmed component, within 5 cm of the proximal end of the implant.

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43
Q

What are classification systems of supracondylar periprosthetic (TKA) fractures?

A
  1. Rorabeck and Taylor
  • Type I – undisplaced fracture, prosthesis intact
  • Type II – displaced fracture, prosthesis intact
  • Type III – displaced or undisplaced fracture, prosthesis is loose or failing
  1. Su classification
  • Type I – fracture proximal to the femoral component
  • Type II – fracture originates at the proximal end of the femoral component and extends proximally
  • Type III – fracture line is distal to the upper edge of the component’s anterior flange
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44
Q

What are the management options for supracondylar periprosthetic (TKA) fractures?

A
  1. Nonoperative
  2. Plates and screws
  3. Fixed-angle devices
  • Dynamic condylar screw
  • Blade plate
  • Locking plates*
  1. Intramedullary nails
  • Supracondylar nail*
  • Antegrade nail
  • Retrograde nail
  1. Revision arthroplasty*
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45
Q

What is the management of TKA periprosthetic fractures based on Su classification?

A
  1. Type I – antegrade or retrograde IM nail
  2. Type II – fixed angle device or retrograde supracondylar nail
  3. Type III – fixed angle device or revision arthroplasty
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46
Q

What is the incidence of periprosthetic (TKA) tibia fractures?

[JAAOS 2018;26:e167-e172]

A

0.4 - 1.7%

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47
Q

What radiographic finding should make you think of a periprosthetic (TKA) tibia fracture?

[JAAOS 2018;26:e167-e172]

A

Proximal tibia varus (associated with Felix type I and II)

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48
Q

What test should be ordered to evaluate for (TKA) implant stability if unclear on radiographs?

[JAAOS 2018;26:e167-e172]

A

CT scan

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49
Q

In what cases should an infectious workup be performed (in context of TKA periprosthetic fracture)?

[JAAOS 2018;26:e167-e172]

A
  1. History of PJI
  2. Imaging findings that are concerning for infection
  3. Severe fracture pattern that is inconsistent with mechanism
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50
Q

What is the Classification system for TKA periprosthetic fractures of the tibia?

[Revision Total Hip and Knee Arthroplasty 2012, Berry et al]

A

Mayo Clinic classification of periprosthetic tibial fractures (aka Felix classification)

  • Four types
    • Type I - fractures involve the tibia plateau and extend into the metaphysis (usually medial plateau and involve the tibial baseplate/bone interface)
    • Type II - fractures involve the meta-diaphyseal area and extend to the tibial stem/bone interface
    • Type III - fractures occur distal to the tibial stem
    • Type IV - tibial tubercle fractures
  • Three subcategories
    • A - well fixed tibial component
    • B - loose tibial component
    • C - intraoperative fracture
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51
Q

What are risk factors for periprosthetic (TKA) fracture of the tibia?

[Revision Total Hip and Knee Arthroplasty 2012, Berry et al]

A
  1. Varus malalignment
  2. Rotational malposition
  3. Knee instability
  4. Loose components
  5. Keeled tibial components
  6. Trauma
  7. Proximal tibia osteolysis
  8. Poor bone quality
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52
Q

What are the general considerations for management of periprosthetic tibial plateau fractures?

[JAAOS 2018;26:e167-e172]

A
  1. Consider nonoperative treatment if:
  • Stable component
  • Well aligned tibial component
  • Well aligned mechanical tibial axis
  1. Consider operative treatment if:
  • Major fracture displacement or angulation
  • Unstable component
  • Altered tibial component alignment
  1. Construct options
  • Component stable = locking plates (IM nail in select cases)
  • Component unstable = revision TKA with long stemmed tibial component
  • Substantial bone loss or comminution = megaprosthesis (rare)
53
Q

What is the management of proximal tibia periprosthetic fractures?

[Revision Total Hip and Knee Arthroplasty 2012, Berry et al]

A
  1. Nonoperative
  • Consider for all types with stable component
  • Consider in those with unstable component when fracture healing is desired prior to revision
  1. Operative
  • Type IA - nonoperative or ORIF
  • Type IB - tibia revision with diaphyseal-fitting stem +/- cement/bone graft/augments to fix defects
  • Type IC - fixation with cancellous screw prior to prosthesis insertion OR use a stemmed tibial component
    • Type IIA - nonoperative or ORIF
  • Type IIB - tibia revision with diaphyseal-fitting stem +/- ORIF +/- bone graft OR tumor prosthesis
  • Type IIC - tibia revision with diaphyseal-fitting stem
    • Type IIIA - nonoperative OR ORIF (locking plate)
  • .Type IIIB - rare, consider delayed revision after fracture heals
    • Type IV - ORIF with screw or wire if displaced OR nonoperative if nondisplaced
54
Q

What are the clinical features of arthrofibrosis after TKA?

[The Journal of Arthroplasty 32 (2017) 2604e2611]

A
  1. Loss of ROM due to stiffness (no consensus on degree of ROM loss to define arthrofibrosis)
  2. Pain with palpation
  3. Swollen/inflamed knee
55
Q

What are the functional deficits of loss of knee ROM?

[The Journal of Arthroplasty 32 (2017) 2604e2611]

A
  1. Flexion required
  • ~70° for typical gait
  • 80-90° for stair ascent and descent
  • 125° for squatting to pick object up from floor
  1. Extension
  • 5° loss of extension causes limp
  • 15° flexion contracture results in 22% more extensor mechanism demand
56
Q

What is the management of arthrofibrosis post TKA?

[The Journal of Arthroplasty 32 (2017) 2604e2611]

A
  1. Aggressive physiotherapy
    * NSAIDs and RICE, stretching, bracing, PROM/AROM, quads strengthening
  2. <3 months and no improvement with nonop (as early as 6 weeks)
  • MUA
    • Technique:
      • GA, muscle relaxation, hip flexion to 90°, progressive flexion, hold 30 seconds at new max
    • .Complications:
      • Fracture, wound dehiscence, patellar tendon avulsion, quads strain or rupture, hemarthrosis, HO, pulmonary embolism
        3. >3 months and no improvement with nonop or failed MUA
  • First line = Arthroscopic debridement
    • Technique:
      • Release of adhesions in suprapatellar pouch, gutters and intercondylar notch
  • Second line = Open debridement
    • Performed after failure of arthroscopic debridement
    • Complications – damage to prosthesis, hemarthrosis, extensor mechanism disruption, fracture, infection, neurovascular injury
  • Third line = revision TKA
    • Technique:
      • Partial or complete replacement
    • Considered if potential mechanisms identified including – improper component sizing, rotation, alignment or soft tissue balance
57
Q

What is the expected improvement in knee ROM following MUA?

A

Increased flexion range of motion 30-42° and overall knee range of motion 31-47°

58
Q

What is the mechanism of osteolysis in TKA?

[JAAOS 2015;23:173-180]

A

Polyethylene wear debris results in macrophage activation following phagocytosis leading to osteoclast activation and resultant bone resorption

  • Main inflammatory factors resulting in osteoclast activation include TNF-α, IL-1, IL-6, IL-8, RANKL [Instr Course Lect. 2013; 62: 201–206.]
59
Q

What are the modes of polyethylene wear in TKA?

[JAAOS 2015;23:173-180]

A
  1. Adhesive
  2. Abrasive
  3. Fatigue

***Also:

Mode 1: Articulation between intended surfaces

  • Femoral head and acetabular cup
  • Most common mode of failure in a well-functioning prosthesis

Mode 2: Articulation of primary bearing surface and a material that was never intended to be a bearing surface

  • Femoral head and metal backing (an acetabular lining that has worn though to its metal backing)

Mode 3: Articulation between intended surfaces but in the presence of third body particles

  • PMMA, bone, metal debris, corrosion wear (metal on metal)

Mode 4: Articulation between 2 non-bearing secondary surfaces.

  • Backside wear is an example–back of poyethylene insert on its metal backing

Mnemonic:

Mode 1 – primary to primary

Mode 2 – 2 diff surfaces

Mode 3 – 3rd body

Mode 4 – backside (last) (or 22 – 2 x secondary)

60
Q

What polyethylene particle size leads to the greatest stimulation of macrocytic activation?

[JAAOS 2015;23:173-180]

A

0.2 - 7µm

61
Q

What factors increase the risk for osteolysis development post TKA?

[JAAOS 2015;23:173-180]

A
  1. Patient factors
  • Young, active
  • Obese
  1. Surgical technique
  • Component malposition (eg. varus)
  • Poor balance
  1. Material factors
  • Sterilization method
    • Gamma radiation in air increased risk compared to ethylene oxide or gamma radiation in inert gas
  • Non-highly crosslinked polyethylene
  • Backside wear
    • Micromotion between the poly and tibial tray
      • Increased with nonpolished tibial trays, poor locking mechanism
  • Thinner poly
  • Noncemented baseplates supplemented with tibial screws
  • Metal backed patellar components
62
Q

What are the features of osteolytic lesions post TKA?

[JAAOS 2015;23:173-180]

A
  1. Typically focal, well-marginated
  2. Often with cortical thinning or perforation
  3. Arise at margin of synovial cavity extending along bone-implant interface
  4. Tibial lesions are usually under the tibial tray and extend along the stem
  5. Femoral lesions occur adjacent to the femoral component (more common in posterior condyles), extend for a variable distance proximally
63
Q

What is the recommended monitoring for osteolytic lesions post TKA?

[JAAOS 2015;23:173-180]

A

Routine followup annually for first 3 years then every 2 years thereafter

  • Incidental osteolysis noted
    • Obtain oblique radiograph (better visualizes the posterior condyles)
    • Continue close observation if asymptomatic, nonprogressive lesions, stable components
  • Symptomatic osteolysis/progressive osteolysis/component failure
    • Obtain CT scan (determine size, location)
    • Plan for surgery
      • Tibial osteolytic lesions
        • Poly exchange and impaction bone grafting
          • Consider if lesion is small (<2cm), component stable and well aligned
        • Tibial revision
          • Consider diaphyseal stem fixation, augments, screw in cement, porous metal sleeves
      • Femoral osteolytic lesions
        • Femoral revision
          • Consider stemmed implant, distal or posterior augments, increased constraint if collaterals compromised
64
Q

What are the causes of bone loss in TKA?

[JAAOS 2017;25348-357]

A
  • Stress shielding
  • Osteolysis
  • Osteonecrosis
  • Infection
  • Implant loosening
65
Q

What is the classification for bone loss in TKA?

[J Am Acad Orthop Surg 2011;19: 311-318] [Revision Total Hip and Knee Arthroplasty 2012, Berry et al] [JAAOS 2017;25:348-357] -

A

Anderson Orthopaedic Research Institute (AORI) Classification of Bone Defects

  1. Type 1 - intact metaphyseal bone
  • Good cancellous bone at or near a normal joint line level
  • Minor bone defects that do not compromise the stability of the component
  1. Type 2 - damaged metaphyseal bone
  • Loss of cancellous bone that requires cement fill, augments, or small bone grafts to restore a reasonable joint line
  • Subclassifiead
    • Type 2A - defect involves one femoral or tibial condyle
    • Type 2B - defect involves both condyles
  • Type 2 femur – bone loss is distal to the epicondyles
  • Type 2 tibia – bone loss extends as low as, but not below, the tip of the proximal fibula
    3. Type 3 - deficient metaphyseal segment
  • Deficient bone that compromises a major portion of either condyle or plateau
  • These defects usually require a large structural allograft, a rotating hinged component or custom components
66
Q

In revision TKA what landmarks can be used to restore the joint line?

[JAAOS 2017;25:348-357]

A
  1. Lateral epicondyle = 25mm proximal
  2. Medial epicondyle = 30mm proximal
  3. Adductor tubercle = 40-45mm proximal
  4. Inferior patellar pole = 10mm proximal
  5. Meniscal scar
  6. Tip of fibula = 15mm distal
67
Q

In revision TKA what implants should be considered?

[JAAOS 2017;25:348-357]

A
  1. Posterior stabilized
    * Indication – intact collateral, no varus/valgus instability
  2. Unlinked constrained (varus/valgus constrained liner)
  • Indication – mild to moderate varus/valgus instability
  • Functions to limit rotation, M-L translation, varus/valgus angulation
  1. Rotating hinge
    * Indicated for patients with bone loss and compromised collateral ligaments, compromised extensor mechanism or severe flexion-extension mismatch
  2. Modular segmental (megaprosthesis)
68
Q

What other implant options should be considered to deal with bone loss in revision TKA?

[JAAOS 2017;25:348-357]

A
  1. Stems
  • Bypass deficient metaphyseal bone and engage the diaphysis
  • Can be cemented, cementless, or hybrid
  1. Cement
    * Indication = <5mm defect affecting <50% of bone surface area
  2. Cement and screw
    * Indication = 5-10mm defect
  3. Impaction grafting
  • Advantage
    • Restores bone stock
    • Cost effective
  • Disadvantage
    • Technically difficult
    • Risk of intraop fracture
    • Disease transmission
    • Infection
    • Graft resorption
  • Can use in contained and uncontained defects (with mesh)
  • Impact graft with trial stem in place then cement final stem
  1. Bulk structural allograft
  • Advantages – good initial support, restores bone stock
  • Disadvantage – prolonged surgical time, nonunion, delayed union, disease transmission, infection, graft resorption
  • Femoral head allograft is commonly used (tibia is prepared with acetabular reamer, graft is fixed with cancellous screw)
  1. Metal augments
  • Indication
    • Uncontained defects 5-10mm
    • ≥40% of bone-implant interface unsupported
    • Periphery of defect involves ≥25% of cortex
  • Advantages
    • Immediate support
    • Short surgical time
    • No resorption
  • Disadvantages
    • Expense
    • No bone restoration
    • Requires additional bone resection
    • Limitation in size and shape
  1. Metaphyseal cones and sleeves
  • Advantages
    • Fills large defects
    • Immediate structural support
  • Disadvantages
    • Expense
    • No bone restoration
    • Requires additional bone resection
    • Difficult removal if revision required
  • The primary difference between trabecular metal cones and metaphyseal sleeves is that the interface of the sleeve with the implant is created via a Morse tapered junction rather than with cement. [JAAOS 2011;19:311-318]
69
Q

What are the advantages and disadvantages of uncemented vs. cemented stems in revision TKA?

A
  1. Cemented
  • Advantages
    • Can be shorter (do not need to engage diaphysis)
    • Allow delivery of antibiotics
    • Ideal for osteoporotic bone/capacious canals/ipsilateral THA
  • Disadvantages
    • Difficult removal
      1. Uncemented
  • Advantages
    • Obtain correct limb alignment
  • Disadvantages
    • Require offset options
    • Long stems required to engage diaphysis
    • Risk of iatrogenic fracture
    • End-of-stem pain
70
Q

What is the approach to femoral bone loss in revision TKA?

[JAAOS 2017;25:348-357]

A
  1. Assess integrity of collateral ligaments
    * If compromised = manage with increased constraint (rotating hinge or megaprosthesis)
  2. Estimate the amount of distal bone loss based on references to the epicondyles or adductor tubercle
  • Distal defects <10mm = manage with cement (with/without screws), morcelized graft, or metal augments
  • Distal defects >10mm = manage with tantalum cone, metaphyseal sleeve, or bulk structural allograft
71
Q

What is the approach to tibial bone loss in revision TKA?

[JAAOS 2017;25:348-357]

A
  1. Assess integrity of the tibial tuberosity
    * If compromised = manage with increased constraint (rotating hinge or megaprosthesis)
  2. Estimate the amount of proximal bone loss based on references to the fibular head
  • Proximal defects <10mm = manage with cement (with/without screws), impaction grafting or metal augments
  • Proximal defects >10mm = manage with tantalumn cone, metaphyseal sleeve, or bulk structural allograft
72
Q

What are the principles of revision TKA? [JAAOS 2017;25:348-357]

A
  1. Rebuild the tibial platform
    * Make a fresh cut perpendicular to the mechanical axis of the tibia
  2. Reestablish the flexion gap
  • Restore posterior condylar offset or posteriorize the femoral component with an offset stem
  • Ensure a rectangular flexion gap with proper external rotation of implant
  1. Reestablish the extension gap
    * Distal femoral implant should be at native joint line (use above references)
73
Q

What are the options to address extra-articular deformity in planned TKA?

[Orthopedics 2007; 30(5): 373]

A
  1. Asymmetrical intra-articular resection and soft tissue balancing
  2. Corrective osteotomy prior to TKA or at time of TKA
74
Q

When is correction of an extra-articular deformity by intra-articular resection indicated in context of TKA?

[Orthopedics 2007; 30(5): 373][JAAOS 2016;24:220-230]

A
  1. Indicated if the line perpendicular to the mechanical axis of the femur at the femoral condyle does not pass through the insertions of the collateral ligaments. (B)
  2. Indicated if the line drawn from the medullary canal of the tibia distal to the angular deformity passed within the tibial condyle (C)
  3. In general, an intra-articular compensatory correction can be achieved if the deformity is far from the joint and limited to <20° in the coronal plane on the femoral side and <30° on the tibial side.
75
Q

When is correction of an extra-articular deformity by corrective osteotomy indicated?

[Orthopedics 2007; 30(5): 373]

A
  1. Indicated if the collateral ligament or patellar attachment will be jeopardized by bone resection or if large asymmetric soft-tissue gaps will be created that will present difficulties for soft-tissue balancing
  2. Indicated if the line drawn from the medullary canal of the tibia distal to the angular deformity passes outside the tibial condyle
76
Q

What is the impact of the location of the extra-articular deformity in context of TKA?

[JAAOS 2016;24:220-230]

A

The closer the deformity is to the joint the greater the impact on knee alignment

  • For example, if the apex of a femoral or tibial deformity is located at a distance from the joint that corresponds to 25% of the length of the bone, the effect of the deformity will be twice that of a deformity located at a distance corresponding to 50% of the length of the bone.
77
Q

What are the management options of a fracture nonunion prior to TKA?

[Orthopedics 2007; 30(5): 373]

A
  1. Perform ORIF of the fracture, along with a standard arthroplasty
  2. Use a long-stem TKA to fix the fracture, similar to the technique used with osteotomy
  3. Use a custom metaphyseal replacement prosthesis if the fracture is adjacent to the joint and severely comminuted
78
Q

What are the risk factors for extensor mechanism disruption after TKA?

[JAAOS 2015;23:95-106]

A
  1. Multiply operated knee
  2. Systemic conditions (RA, renal disease, DM)
  3. Obesity
  4. Iatrogenic injury during TKA
  5. Malposition and instability
79
Q

What are risk factors for quadriceps rupture post TKA?

[JAAOS 2015;23:95-106]

A
  1. Aggressive patella resection compromising insertion of quads
  2. Superior lateral genicular artery disruption
80
Q

What are risk factors for patella fracture after TKA?

[JAAOS 2015;23:95-106] [JBJS 2014;96:e47(1-9)]

A
  1. Overresection of the patella (<12mm)
  2. Implant malalignment
  3. Disruption of patella blood supply (lateral release)
  4. Large central patellar peg
  5. Metal-backed uncemented patellar component
81
Q

What are risk factor for patellar tendon rupture?

[JAAOS 2015;23:95-106]

A
  1. Systemic disease
  2. Stiff knee (revision surgery, previous HTO or tibial tubercle transfer)
82
Q

What are the layers of the quadriceps tendon?

[JAAOS 2015;23:95-106]

A

Trilaminar structure

  • Superficial – rectus femoris (pass over the patella and become continuous with the patellar tendon)
  • Middle – vastus medialis and lateralis
  • Deep – vastus intermedius
83
Q

What are management options for a deficient extensor mechanism after TKA?

[JAAOS 2015;23:95-106]

A
  1. Nonoperative
  • Indicated for elderly, sedentary patient or poor surgical candidate
  • Involves walking aids and knee brace (locking in extension while ambulating and unlocking allowing flexion when sitting)
  1. Operative
  • Primary repair
    • Poor outcomes, opt for reconstruction instead
  • Reconstruction with fresh frozen allograft or autograft
    • Achilles allograft
      • Useful when the patella and patellar component are intact and patella can be mobilized within 3-4cm of joint line
    • Whole extensor mechanism allograft
      • Useful when patella is deficient or if patella cannot be mobilized to within 3-4 cm of joint line
    • Semitendinosus autograft
  • Reconstruction with synthetic material (mesh)
  • Gastrocnemius rotational flap
    • Medial head of gastroc with medial portion of achilles
      1. Keys for reconstruction
  • Graft tensioned in extension to prevent extensor lag
  • Knee is immobilized in extension or hyperextension for 6-8 week
84
Q

What is the recommended treatment for quadriceps tendon rupture following TKA?

[JBJS 2014;96:e47(1-9)]

A
  1. Partial rupture (extensor lag <20°)
    * Nonoperative (cast or brace)
  2. Compete rupture (extensor lag >20°)
  • Direct repair
    • Midsubstance = end-to-end AND augment
    • Insertional with adequate bone stock = longitudinal drill holes AND augment
    • Insertional with inadequate bone stock = suture anchor repair AND augment
85
Q

What are the advantages of a UKA vs. TKA?

[JAAOS 2007;15:9-18]

A
  1. Preservation of normal knee kinematics
  2. Lower perioperative morbidity
  3. Less blood loss
  4. Accelerated patient rehabilitation and recovery
86
Q

What are the indications for UKA?

[JAAOS 2007;15:9-18]

A

Classic indications (proposed by Kozinn and Scott):

  • Unicompartmental OA or osteonecrosis of the medial or lateral compartments
  • Age >60
  • Low activity demand
  • Minimal pain at rest
  • ROM arc >90°
  • <5° flexion contracture
  • Angular deformity <15° that is passively correctable to neutral

***No longer valid

87
Q

What are the indications for the Oxford UKA?

[Orthop Clin N Am 46 (2015) 113–124]

A
  • Bone-on-bone anteromedial OA
  • Ligamentously normal knee with intact ACL
  • Correctable varus deformity
  • Normal lateral joint space on valgus stress view
88
Q

What are the contraindications for UKA?

[JAAOS 2007;15:9-18]

A
  1. Classic contraindications:
  • Inflammatory arthritis
  • Age <60
  • Weight >81kg (181 lbs)
  • High activity level
  • Pain at rest (suggesting inflammatory arthritis)
  • Patellofemoral pain
  • Exposed bone in the patellofemoral or opposite compartment
  1. Other contraindications
    * Osteonecrosis due to corticosteroid use (risk of osteonecrosis of adjacent compartments)
89
Q

What are the contraindications for the Oxford UKA?

[Orthop Clin N Am 46 (2015) 113–124]

A
  • Inflammatory arthritis
  • Previous HTO
  • ACL deficiency
  • MCL contracture with inability to correct varus deformity
  • Weightbearing cartilage wear of the lateral compartment
  • Severe patellofemoral arthrosis with lateral facet disease, lateral subluxation, and trochlear grooving

***NOTE – mild to moderate PF disease is not considered a contraindication

***NOTE – obesity is not considered a contraindication

90
Q

What pattern of osteoarthritis is the primary indication for medial Oxford UKA?

[Orthop Clin N Am 46 (2015) 113–124]

A

Medial compartment OA with an anteromedial pattern

  • Anteromedial OA is associated with an intact ACL where as posteromedial OA is associated with ACL deficiency
91
Q

What are the main causes of mobile-bearing failure vs. fixed-bearing failure?

[Joints 5(1) 2017: 44-50]

A
  1. Mobile-bearing = bearing dislocation
  2. Fixed-bearing = polyethylene wear and aseptic loosening
92
Q

What are the main causes of failure of UKA?

[Joints 5(1) 2017: 44-50]

A
  1. Bearing dislocation
  • Major complication of mobile bearing
  • Causes:
    • Malposition of components
    • Unbalanced flexion-extension gaps
    • Impingement of the insert on adjacent bone or tibial/femoral component
    • Instability due to MCL injury
    • Secondary to femoral or tibial component loosening
  • Treatment options for bearing dislocation
    • Bearing exchange
    • Revision UKA or conversion to TKA
      1. Aseptic mechanical loosening
  • Causes:
    • Undercorrection of the deformity
    • Component malalignment
    • ACL deficiency
    • Excessive tibial slope
    • Bearing dislocation
  • Treatment options
    • Revision UKA or conversion to TKA
  1. Polyethylene wear
  • More common in fixed-bearing designs
  • Causes:
    • Component malposition
    • Undercorrection of deformity
    • Poly thickness <6mm
    • Reduced conformity in the design
    • Manufacturing process and sterilization method
  • Treatment options?
    • Insert exchange or conversion to TKA
  1. Progression of OA in unreplaced compartments
  • Causes:
    • Overcorrection of deformity, inflammatory arthritis
    • PF degeneration can occur with impingement of the patellar cartilage on the femoral component
      • Avoid by sizing appropriately and avoid placing femoral component beyond the sulcus terminalis [JAAOS 2007;15:9-18]
    • Treatment options for progression of OA?
      • Conversion to TKA or replacement of affected compartment
  1. Infection
  • Incidence lower than TKA (~0.2-1%)
  • Treatment options:
    • Acute – I&D and liner exchange
    • Chronic – one or two stage revision to TKA
  1. Impingement
  2. Periprosthetic fracture
  • More commonly involve the tibial condyles
  • Treatment options for tibial periprosthetic fracture:
    • Nonop – minimal translation or varus deformity
    • ORIF – unacceptable translation or deformity
    • Conversion to TKA – tibial component loosening, severe displacement or nonunion
  1. Retaining of cement debris
  2. Arthrofibrosis
  • Incidence lower than TKA
  • Treatment options:
    • MUA +/- arthroscopic debridement
  1. Unexplained pain
93
Q

What are the surgical principles of performing a UKA?

[JAAOS 2007;15:9-18] [Orthop Clin N Am 46 (2015) 113–124][JISAKOS 2017;0:1–11]

A
  1. Directly visualize the ACL and contralateral compartment for disease – convert to TKA if affected
  2. Tibial component should be perpendicular to the long axis of the tibia in the coronal plane
  3. Tibial slope should match the native tibial slope (some recommend slope <7° to protect the ACL from degeneration/rupture)
  4. Femoral component should be perpendicular to the tibial component in the coronal plane
  5. Soft tissue releases should never be performed
  6. Restore ligament tension and balance by positioning the components accurately and inserting the appropriate thickness poly
  7. Avoid overcorrection/undercorrection of the deformity
  • Goal in medial UKA = 1-4° varus
  • Goal in lateral UKA = 3-7° valgus
94
Q

What is the role for valgus and varus stress radiographs in planning UKA in a varus knee with medial compartment OA?

[Orthop Clin N Am 46 (2015) 113–124]

A
  1. Valgus stress – demonstrates if the deformity is correctable and if the lateral compartment cartilage is maintained
  2. Varus stress – demonstrates if the medial compartment is bone-on-bone OA
95
Q

What is the likelihood of requiring a TKA after undergoing ORIF for a tibial plateau ORIF?

[JAAOS 2018;26:386-395]

A
  1. 5x more likely in tibial plateau ORIF compared to matched controls
  2. 7.3% undergo TKA after 10 years
96
Q

What are the risk factors for requiring TKA following tibial plateau ORIF?

[JAAOS 2018;26:386-395]

A
  • Increasing age
  • Split-depression or Condylar fractures
  • Female
97
Q

What are the preoperative considerations for a TKA following tibial plateau ORIF?

[JAAOS 2018;26:386-395]

A
  1. Evaluate for infection
  • Aspirate, cultures and blood markers
  • Intraoperative frozen section analysis
  1. Previous scars
  2. Hardware
  3. Bone loss
    * Consider cement augmentation, metaphyseal cones or sleeves, wedges and bone graft
  4. Alignment (intra- and extra-articular)
    * Consider computer navigation and custom cutting blocks
  5. Implant considerations
  • Cement and stemmed tibial component in most cases
  • Level of constraint
  1. Periarticular adhesions and stiffness
  2. Joint instability
98
Q

What is the suggestion for incision when previous incisions are present in context of TKA post tib plateau ORIF?

[JAAOS 2018;26:386-395]

A
  1. Most recent scar should be used (provided it allows for adequate exposure)
  2. Use the most lateral scar
  3. Short peripatellar incisions may be ignored
  4. Previous transverse incision can be crossed longitudinally at right angles
99
Q

What approach is recommended for TKA post tibial plateau ORIF?

[JAAOS 2018;26:386-395]

A
  1. Medial parapatellar
  2. Consider quads snip or tibial tubercle osteotomy for increased exposure
100
Q

What is the risk of infection when undergoing TKA after tibial plateau ORIF?

[JAAOS 2018;26:386-395]

A

3-20%

101
Q

What are the advantages of TKA for post-traumatic arthritis following tibial plateau fractures?

[JAAOS 2018;26:386-395]

A
  1. Improved pain
  2. Minor improvement in ROM
102
Q

What are the advantages of TKA for the primary management of tibial plateau fractures?

[JAAOS 2018;26:386-395]

A
  1. Immediate stability
  2. Early mobilization
  3. Decreased reoperation rates
103
Q

What population can be considered for primary TKA for tibial plateau fracture?

[JAAOS 2018;26:386-395]

A

Elderly and osteoporotic

104
Q

What is the recommended timing for a primary TKA for tibial plateau fracture?’

[JAAOS 2018;26:386-395]

A
  1. At the earliest opportunity by an experienced arthroplasty surgeon
  2. Delayed fashion in the presence of severe comminution to allow fracture consolidation and tibial tubercle healing
105
Q

What are the 3 forms of osteonecrosis of the knee?

[JAAOS 2011;19:482-494]

A
  1. Secondary ON
  2. Spontaneous ON (SONK)
  3. Post-arthroscopic ON
106
Q

What are the features of the 3 forms of osteonecrosis of the knee?

A
  1. Secondary ON
  • Age = <45
  • Sex = men > women
  • Bilaterality = >80%
  • Other joints = >90% (hip, shoulder, ankle)
  • Risk factors:
    • Direct causes (trauma, caisson disease, chemo, radiation, Gaucher)
    • Indirect causes (alcohol abuse, coagulation abnormalities, corticosteroids, inflammatory bowel disease, organ transplant, SLE, smoking)
  1. SONK
  • Age = >50
  • Sex = women > men (3:1)
  • Bilaterality = <5%
  • Other joints = no
  • Risk factors = idiopathic, chronic mechanical stress or microtrauma
  1. Postarthroscopic ON
  • Age = any
  • Sex = no predilection
  • Bilaterality = never
  • Other joints = no
  • Risk factors = meniscectomy, cartilage debridement, ACL reconstruction, laser or RFA surgery
107
Q

What imaging should be ordered for patients with suspected or confirmed osteonecrosis of the knee?

[JAAOS 2011;19:482-494]

A
  1. Radiographs
  • Good for staging and monitoring progression
  • Can also screen for other diseases on differential
  1. MRI
    * Good for early detection and assessing extent of disease (surgical planning)
  2. Bone scan
    * Good for early detection in patients unable to get MRI
108
Q

What is the radiographic classification of osteonecrosis of the knee?

[JAAOS 2011;19:482-494]

A

Ficat classification

  • Stage I – no radiographic changes
  • Stage II – mottled sclerosis
  • Stage III – ‘crescent’ sign indicating subchondral fracture
  • Stage IV – collapse of subchondral bone
109
Q

What are the treatment options for osteonecrosis of the knee?

[JAAOS 2011;19:482-494]

A
  1. Nonsurgical management
  • Protected WB, analgesia, NSAIDs
  • Not indicated for secondary ON
  • Successful in ≥89% of early SONK with no radiographic changes and no collapse
  1. Joint preserving procedures (limited evidence)
  • Core decompression – if no subchondral collapse
  • Bone graft through extra-articular cortical window – early ON
  • Osteochondral autograft – SONK with subchondral collapse
  • Osteotomy
  1. Arthroplasty
  • TKA – if subchondral collapse or failure of joint-preserving treatment
    • Recommended for secondary ON
  • UKA
    • Not recommended for secondary ON (frequently involves multiple condyles)
110
Q

What is the most common metal used in manufacturing of femoral TKA components?

[JAAOS 2016;24:106-112]

A

Cobalt-chromium

111
Q

What are the most common metal sensitizers (allergens)? [JAAOS 2016;24:106-112]

A

Nickel, followed by cobalt and chromium

112
Q

What is the prevalence of metal sensitivity in the general population?

[JAAOS 2016;24:106-112]

A

10-15%

113
Q

What type of hypersensitivity reaction occurs with TKA metal reactions?

[JAAOS 2016;24:106-112]

A

Delayed type IV cell-mediated allergic reaction

  • Interaction between T-cells, macrophages and monocytes (not antibodies)
114
Q

What screening is available preoperative for patients at risk of metal hypersensitivity (in TKA)?

[JAAOS 2016;24:106-112]

A

No evidence to recommend routine skin tests, in vitro lab tests (leukocyte migration inhibition test) or screening questionnaires

115
Q

What are the clinical presentations of metal hypersensitivity in TKA?

[JAAOS 2016;24:106-112]

A
  1. Eczematous dermatitis
    * Often located in the lateral parapatellar region
    * Refer to dermatologist for topical or systemic steroids
  2. Severe painful persistent synovitis
  • Workup for infection
    • CRP, ESR, aspirate for cell count, differential, culture
  • The diagnosis of metal hypersensitivity is one of exclusion
  • Do not obtain serum metal levels
  • No proven nonoperative treatments
  • No strong evidence to support revision TKA
    • Patients may be offered revision TKA with zirconium or titanium alloy with nitride coating
116
Q

What is the incidence of wound complications after TKA requiring further surgery?

[JAAOS 2017;25:547-555]

A

0.33% (data from Mayo Clinic Registry with >17,000 TKAs)

117
Q

What is the incidence of postoperative incisional drainage following TKA?

[JAAOS 2017;25:547-555]

A

1-10%

118
Q

What is considered ‘persistent wound drainage’ post TKA?

[JAAOS 2017;25:547-555]

A

Continued drainage from a surgical incision for >72 hours

  • Substantial drainage (>2x2 area of gauze) beyond this time is abnormal
119
Q

What is the wound strength of the healing incision at 1 week, 3 weeks, 3 months and ≥1 year (post TKA)?

[JAAOS 2017;25:547-555]

A

1 week = 3% of final strength

3 weeks = 30% of final strength

3 months = 80% of final strength

1 year = never achieves strength of normal tissue

120
Q

What are the preoperative modifiable risk factors or medical conditions that increase the risk of soft tissue complications and what optimization strategies should be considered?

[JAAOS 2017;25:547-555]

A
  1. Diabetes = tight glycemic control
  2. RA = medication review
  • Hold 1-2 weeks preop, restart 2 weeks postop
  • 2-3x greater risk of surgical site infection compared to OA
  1. Smoking = cessation at least 6-8 weeks preop
    * ~2x rate of deep infection
  2. Obesity = weight loss from caloric reduction and/or bariatric surgery
  3. Malnutrition = nutritional screening, education and/or supplementation
  • Increased risk associated with:
    • Serum albumin <3.5g/dL
    • Total lymphocyte count <1,500mm3
    • Transferrin level <200mg/dL
121
Q

If concerned about wound healing in TKA, when should you consider preoperative consult with plastics?

[JAAOS 2017;25:547-555]

A
  1. Anticipiated difficulties with closure or wound healing
    * Previous incision, severe varus or rotational deformity, prior trauma with contracted or immobile skin
  2. Prior soft tissue flaps
122
Q

What is the blood supply to the anterior skin about the knee?

[JAAOS 2017;25:547-555]

A

Medial

  • From deep perforating vessels passing through anterior thigh muscles and intermuscular septum
  • Arterioles arborize in plane directly superficial to deep fascia of subcutaneous layer
    • Skin flap dissection should be deep to this layerto preserve the perforating arteriolar
      network
123
Q

What is the blood supply to the patella?

[JAAOS 2017;25:547-555]

A

Terminal branches of the peri-patellar anastomoses

  • Arterial contributions from the supreme/descending geniculate artery, the medial and lateral superior geniculate arteries, the anterior tibial recurrent artery and a branch of the profunda femoris artery
  • Blood supply to the patella is separated from the skin by the patellar bursa
124
Q

How should prior incisions be managed when doing TKA?

[JAAOS 2017;25:547-555]

A
  1. Use the most lateral and vertical incision (even if it necessitates a lateral arthrotomy)
  2. Previous transverse incisions should be crossed at 90 degrees
  3. Previous short oblique incisions should be incorporated into a new vertical incision
  4. Minimum 7cm skin bridge
125
Q

What is the most common area of wound complication in a mildine incision in TKA?

[JAAOS 2017;25:547-555]

A

Distal aspect

126
Q

What are important factors in incision and closure to minimize wound complications in TKA?

[JAAOS 2017;25:547-555]

A
  1. Avoid excessive tension on distal incision (should always look like a ‘V’ and not a ‘U’)
  2. Use full thickness skin flaps
  3. Meticulous hemostasis
  4. Tension free closure
  5. Correct wound alignment
  6. Proper closure of distal incision
127
Q

When should surgical intervention be considered to manage postoperative incisional drainage in TKA?

[JAAOS 2017;25:547-555]

A

Profuse and persistent drainage for >5-7 days

128
Q

How should you manage acute incisional drainage post TKA?

[JAAOS 2017;25:547-555]

A
  1. Drainage on days 2-3
  • Keep in hospital
  • Compressive dressing
  • Avoid PT and ROM
  • Short term cessation of anticoagulants
  • Continue mechanical VTE prophylaxis
  • Consider Vac dressing
  1. Drainage >5 days
    * Surgery indicated to prevent deep infection

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