Arthroplasty Flashcards
1
Q
What is the intraop management of flexion contractures in TKA?
[JBJS(B) 2012;94-B, Supple A:112–15]
A
- Remove posterior osteophytes
- Release posterior capsule (off femur and tibia)
- Additional distal femoral resection
* Generally, take an additional 2mm for flexion contractures >10° - Decrease tibial slope
- Avoid implanting components in flexion
- PS knee preferred
- PCL recession in CR knees
* Release from posterior tibia, medial femoral condyle or V-shaped osteotomy of the posterior tibia - Release medial and lateral gastrocnemius
- Post operative splinting, CPM, shoe lift on contralateral side (forces extension), exercises, close followup
2
Q
What are causes of patellar maltracking in TKA?
[JAAOS 2016;24: 220-230]
A
- Internally rotated femoral component
- Medialized femoral component
- Internally rotated tibial component
- Medialized tibial component
- Lateralized patellar button
- Valgus deformity (must restore neutral mechanical axis)
* I.e. >7° valgus positioning of the femoral component - Overstuffing patellofemoral joint
* I.e. Increased net patella thickness (increases tension on lateral retinaculum thereby increasing lateral patellar pull) - Asymmetric patellar resection
3
Q
What are the intraop treatment options for patellar maltracking in TKA?
A
- 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
- Lateral release
- Medial plication
- Tibial tubercle osteotomy
- Quadsplasty
- Component revision
4
Q
What is the technique for performing a lateral release of the patella?
A
- 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]
- Step 1 - Release of distal part
- 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
5
Q
How do you assess patellar height?
A
- Blumensaat’s line
* Should extend to the inferior pole of the patella in 30 degrees of flexion - 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
- 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
- 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
6
Q
What is the treatment of patella baja in TKA?
A
- Lower joint line
* Resect more tibia, resect less distal femur (or augment) - Place patella poly superiorly and trim distal patellar pole
- Tibial tubercle osteotomy moving it cephalad
- Patellectomy
7
Q
What are causes of patella baja?
A
congenital
aquired
- previous surgery: HTO, TTO, ACLR, knee arthroscopy, retrograde femoral nail, arthroplasty (raising joint line in TKA)
- Trauma (scarring)
8
Q
What are 3 factors to consider in valgus TKA and ways to address them?
A
- 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
- 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 - Lateral bone loss
* Hypoplastic or deficient lateral femoral condyle may require augments - will have a tendency to cause femoral component IR if using posterior referencing
* Lateral tibial bone loss can be addressed by increasing the cement mantle or resecting more tibia to allow rim contact
9
Q
What are 3 factors to consider in a varus knee and how to correct them?
A
- 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
- 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 - Medial bone loss
* Consider augments, cement, allogaft bone/synthetic
10
Q
What are the indications for high tibial osteotomy?
A
- Pain located primarily on the medial aspect of the knee
- Medial compartment OA (less than 4mm of medial joint space on standing radiograph)
- Varus knee deformity
- Young patient undergoing articular cartilage restoration or medial meniscus transplant
11
Q
What are the contraindications for HTO?
A
- Less than 90 degrees of flexion
- Flexion contracture >10-15 degrees
- Severe medial compartment articular damage (Ahlback grade III or higher)
- Patellofemoral OA (symptomatic)
- Lateral compartment OA
- Prior lateral meniscectomy
- Inflammatory arthritis
- Ligament instability (especially varus thrust gait)
- Lateral tibial subluxation >1 cm
- Obesity (relative)
- Smoking (relative)
- Age >65 (relative)
12
Q
Describe the preoperative planning and determination of correction in HTO?
[JAAOS 2011;19:590-599]
A
- 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
- angle of correction = angle formed betweeen 2 lines
- proposed osteotomy line = extends form 4cm distal to medial joint line to tip of fibula laterally
- predicted medial osteotomy opening - determined by transferring the proposed osteotomy line to the intersection of the lines oat fujisawa point and measuring the distance between the 2 lines at the end of the osteotomy line
- Line a-b = proposed osteotomy from 4cm distal to joint line medial and to tip of fibula laterally
- Alpha = angle of correction
- b1-c = gap in mm for correction
13
Q
What are the technical challenges of TKA after HTO?
[AAOS comprehensive review 2, 2014]
A
- Previous incisions
- Hardware
- Patella baja (difficult exposure)
- Tibial abnormalities (metaphyseal offset after closing wedge osteotomy)
14
Q
What are the indications for a varus producing distal femoral osteotomy?
[Arthroscopy Techniques 2016: 5(6); e1357-e1366]
A
- Genu valgus alignment
- Isolated lateral compartment OA
- Chondral or osteochondral lesions of the lateral compartment
- Meniscal deficiency of the lateral compartment
- Cartilage repair/restoration of the lateral compartment
- Chronic MCL or cruciate instability
- Refractory patellar instability
15
Q
What are the contraindications for a varus producing DFO?
[Arthroscopy Techniques 2016: 5(6); e1357-e1366] [JAAOS 2018;26:313-324]
A
- Inflammatory OA
- Medial or patellofemoral OA
- Flexion contracture >15°
- Flexion <90°
- Deformity >15°
- Tibial subluxation
- Gross knee instability
- Severe lateral compartment bone loss
- Nicotine use (relative)
- Obesity (relative)
- Age >50 (relative)
- History of septic arthritis (relative)
- Inability to comply with postoperative instructions
16
Q
What test should be ordered to evaluate for (TKA) implant stability if unclear on radiographs?
[JAAOS 2018;26:e167-e172]
A
CT scan
17
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
18
Q
What are risk factors for periprosthetic (TKA) fracture of the tibia?
[Revision Total Hip and Knee Arthroplasty 2012, Berry et al]
A
- Varus malalignment
- Rotational malposition
- Knee instability
- Loose components
- Keeled tibial components
- Trauma
- Proximal tibia osteolysis
- Poor bone quality
19
Q
What is the management of proximal tibia periprosthetic fractures?
[Revision Total Hip and Knee Arthroplasty 2012, Berry et al]
A
- Nonoperative
- Consider for all types with stable component
- Consider in those with unstable component when fracture healing is desired prior to revision
- 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
20
Q
What are the functional deficits of loss of knee ROM?
[The Journal of Arthroplasty 32 (2017) 2604e2611]
A
- Flexion required
- ~70° for typical gait
- 80-90° for stair ascent and descent
- 125° for squatting to pick object up from floor
- Extension
- 5° loss of extension causes limp
- 15° flexion contracture results in 22% more extensor mechanism demand
21
Q
What is the management of arthrofibrosis post TKA?
[The Journal of Arthroplasty 32 (2017) 2604e2611]
A
- Aggressive physiotherapy
* NSAIDs and RICE, stretching, bracing, PROM/AROM, quads strengthening - <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
- Fracture, wound dehiscence, patellar tendon avulsion, quads strain or rupture, hemarthrosis, HO, pulmonary embolism
- Technique:
- First line = Arthroscopic debridement
- Technique:
- Release of adhesions in suprapatellar pouch, gutters and intercondylar notch
- Technique:
- 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
- Technique:
22
Q
What factors increase the risk for osteolysis development post TKA?
[JAAOS 2015;23:173-180]
A
- Patient factors
- Young, active
- Obese
- Surgical technique
- Component malposition (eg. varus)
- Poor balance
- 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
- Micromotion between the poly and tibial tray
- Thinner poly
- Noncemented baseplates supplemented with tibial screws
- Metal backed patellar components
23
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
- Poly exchange and impaction bone grafting
- Femoral osteolytic lesions
- Femoral revision
- Consider stemmed implant, distal or posterior augments, increased constraint if collaterals compromised
- Femoral revision
- Tibial osteolytic lesions
24
Q
What are the causes of bone loss in TKA?
[JAAOS 2017;25348-357]
A
- Stress shielding
- Osteolysis
- Osteonecrosis
- Infection
- Implant loosening
25
what are the categories of instability following TKA
1. extension (varus/valgus)
2. flexion
3. midflexion
4. genu recurvatum
5. global
26
what are the likely causes of instability when it occurs early (weeks to months) comapred to late?
1. early onset - gap imbalance, component malalignment, iatrogenic ligament injury, patellar tendon rupture or patellar fracture
2. late onset - poly wear, ligament attrition
27
solution table for unbalanced knee
1. loose in flexion/loose in extension
2. loose in flexion/ balanced in extension
3. loose in flexion/ tight in extension
4. balanced in flexion/loose in extension
5. balanced in flexion/tight in extension
6. tight in flexion/loose in extension
7. tight in flexion/balanced in extension
8. tight in flexion/tight in extension
28
what is the treatment of extension instability
SYMMETRIC
* distal femoral augmentation to lower joint line and balance gaps
ASYMMETRIC
* correct the deformity and coronoal plane alignment
* may require release of contracted structures on concave side
* varus-valgus contrained liner may be required
29
what is the definition of flexion instability
1. flexion gap that is larger or more lax than the extension gap
2. results in increased stress on surrounding structures (collateral ligaments, quadriceps, extensor mechanism, hamstrings)
30
what is the cause of flexion instability
1. inability to balance the flexion and extension gaps at primary arthroplasty
2. gradual laxity of the posterior capsule or PCL in cruciate-retaining knees
31
what are the technical factors that can lead to flexion instability
1. too little distal femoral resection in a preexistin flexion contracture
2. overly aggressive posterior condylar resection with undersized femoral implants
3. excessive posterior tibial slope
4. over release of the PCL in the CR knee
32
what are physical examination features of flexion instability
1. current benchmark for dx is the tibial translation test
* examiner subjectively grades anterior tibial translation with the knee at 90° flexion when the quad relaxed and foot free (open chain)
* instability graded as <5mm, 5-10mm, >10mm
2. posterior sag sign
* tibia translates posteriorly when the knee is flexed to 90° and the heel is supported on the table to relex the quad
3. active knee flexion
* patient is seated at the end of the examination table with the kene bent over the edge and the quad is relaxed. if flexion isntability is present, the larger flexion space will cause the tibia to descend and bring the poly out of contact with the posterior condyles. when the patient is asked to actively extend, the physician will note the tibia pull up to articulate with the femur upon initiation of quad contraction, and only after this contact is reestablished, will the tibia extend
4. effusions
5. pain to palpation of the pes anserine and hamstring tendons
33
what is the casue of genu recurvatum
often associated with polio, RA, charcot arthropathy
in polio the quad weakness and ankle equinus leads to ambulation with the knee locked in hyperextension
34
what is the management of genu recurvatum in TKA
1. bracing
2. ps implants with long stems, varus-valgus constrained liners
3. rotating hing can be used but risk of failure due to hyperextension force
35
what are the causes of postop stiffness following TKA
1. preop
* poor preop ROM
* african american
* females
* younger age
* nicotine use
* previous knee surgery
* contralateral TKA stiffness
2. intraop
* flexion-extension gap imbalance
* oversized components
* malrotation of components
* inadquate removal of posterior osteophytes, meniscal remnants, synovial soft tissue
* failure to restore posterior condylar offset
* overstuffing PF joint (inadequate patella resection or anteriorization of femoral component
* anterior overhand of the tibial component
* joint line elevation
3. postoperative
* poor physio compliance
* poor pain control
* postop hemarthrosis
36
In revision TKA what landmarks can be used to restore the joint line?
[JAAOS 2017;25:348-357]
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
37
In revision TKA what implants should be considered?
[JAAOS 2017;25:348-357]
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
3. Rotating hinge
* Indicated for patients with bone loss and compromised collateral ligaments, compromised extensor mechanism or severe flexion-extension mismatch
4. Modular segmental (megaprosthesis)
38
What other implant options should be considered to deal with bone loss in revision TKA?
[JAAOS 2017;25:348-357]
1. Stems
* Bypass deficient metaphyseal bone and engage the diaphysis
* Can be cemented, cementless, or hybrid
2. Cement
* Indication = \<5mm defect affecting \<50% of bone surface area
* advantage - simple, fills defect readily
3. Cement and screw
* Indication = 5-10mm defect, contained ur uncontained defects
* advantage- reliable, reproducible,easily performed, inexpensive
4. bone autograft or allograft
* indication - moderate sized contained defects in young patients
* technique involves impaction grafting suth that graft can support load early with eventual incorporation and remodeling
5. Impaction grafting
* Advantage
* Restores bone stock
* Cost effective
* good initial support
* 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
5. 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 prepared to be 2mm larger than defect and devoid of sclerotic bone, it is then press fit into place +/- augmented with screw fixation
6. 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
7. 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
* intra-opeartive fracture risk
* 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
* cone technique - inolves preparation of defect with broach or burr, cone is press fit into defect, implant is then cemented to cone (thherefore insertion of cone is independent of implant)
* sleeve technique - involves preparation of the diaphysis with sequential reaming, followed by broaching of the metaphysis for accepting the sleeve
8. megaprosthesis
* indication - selected elderly patients with severe bone loss, articular deformities and extreme ligamentous instability
39
What are the advantages and disadvantages of uncemented vs. cemented stems in revision TKA?
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
2. Uncemented
* Advantages
* Obtain correct limb alignment
* Disadvantages
* Require offset options
* Long stems required to engage diaphysis
* Risk of iatrogenic fracture
* End-of-stem pain
40
What is the approach to femoral bone loss in revision TKA?
[JAAOS 2017;25:348-357]
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
41
What is the approach to tibial bone loss in revision TKA?
[JAAOS 2017;25:348-357]
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
42
What are the principles of revision TKA? [JAAOS 2017;25:348-357]
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
3. Reestablish the extension gap
* Distal femoral implant should be at native joint line (use above references)
43
What are the options to address extra-articular deformity in planned TKA?
[Orthopedics 2007; 30(5): 373]
1. Asymmetrical intra-articular resection and soft tissue balancing
2. Corrective osteotomy prior to TKA or at time of TKA
44
When is correction of an extra-articular deformity by corrective osteotomy indicated?
[Orthopedics 2007; 30(5): 373]
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
45
What are the management options of a fracture nonunion prior to TKA?
[Orthopedics 2007; 30(5): 373]
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
46
What are the risk factors for extensor mechanism disruption after TKA?
[JAAOS 2015;23:95-106]
1. Multiply operated knee
2. Systemic conditions (RA, renal disease, DM)
3. Obesity
4. Iatrogenic injury during TKA
5. Malposition and instability
47
What are risk factors for quadriceps rupture post TKA?
[JAAOS 2015;23:95-106]
1. Aggressive patella resection compromising insertion of quads
2. Superior lateral genicular artery disruption
48
What are risk factors for patella fracture after TKA?
[JAAOS 2015;23:95-106] [JBJS 2014;96:e47(1-9)]
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
49
What are risk factor for patellar tendon rupture?
[JAAOS 2015;23:95-106]
1. Systemic disease
2. Stiff knee (revision surgery, previous HTO or tibial tubercle transfer)
50
What are management options for a deficient extensor mechanism after TKA?
[JAAOS 2015;23:95-106]
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)
2. 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
3. Keys for reconstruction
* Graft tensioned in extension to prevent extensor lag
* Knee is immobilized in extension or hyperextension for 6-8 week
51
What is the recommended treatment for quadriceps tendon rupture following TKA?
[JBJS 2014;96:e47(1-9)]
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
52
What are the preoperative considerations for a TKA following tibial plateau ORIF?
[JAAOS 2018;26:386-395]
1. Evaluate for infection
* Aspirate, cultures and blood markers
* Intraoperative frozen section analysis
2. Previous scars
3. Hardware
4. Bone loss
* Consider cement augmentation, metaphyseal cones or sleeves, wedges and bone graft
5. Alignment (intra- and extra-articular)
* Consider computer navigation and custom cutting blocks
6. Implant considerations
* Cement and stemmed tibial component in most cases
* Level of constraint
7. Periarticular adhesions and stiffness
8. Joint instability
53
What is the suggestion for incision when previous incisions are present in context of TKA post tib plateau ORIF?
[JAAOS 2018;26:386-395]
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
54
What approach is recommended for TKA post tibial plateau ORIF?
[JAAOS 2018;26:386-395]
1. Medial parapatellar
2. Consider quads snip or tibial tubercle osteotomy for increased exposure
55
What are the features of the 3 forms of osteonecrosis of the knee?
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)
2. SONK
* Age = \>50
* Sex = women \> men (3:1)
* Bilaterality = \<5%
* Other joints = no
* Risk factors = idiopathic, chronic mechanical stress or microtrauma
3. Postarthroscopic ON
* Age = any
* Sex = no predilection
* Bilaterality = never
* Other joints = no
* Risk factors = meniscectomy, cartilage debridement, ACL reconstruction, laser or RFA surgery
56
What imaging should be ordered for patients with suspected or confirmed osteonecrosis of the knee?
[JAAOS 2011;19:482-494]
1. Radiographs
* Good for staging and monitoring progression
* Can also screen for other diseases on differential
2. MRI
* Good for early detection and assessing extent of disease (surgical planning)
3. Bone scan
* Good for early detection in patients unable to get MRI
57
What is the radiographic classification of osteonecrosis of the knee?
[JAAOS 2011;19:482-494]
Ficat classification
* Stage I – no radiographic changes
* Stage II – mottled sclerosis
* Stage III – ‘crescent’ sign indicating subchondral fracture
* Stage IV – collapse of subchondral bone
58
What are the treatment options for osteonecrosis of the knee?
[JAAOS 2011;19:482-494]
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
2. 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
3. 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)
59
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]
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
3. Smoking = cessation at least 6-8 weeks preop
* ~2x rate of deep infection
4. Obesity = weight loss from caloric reduction and/or bariatric surgery
5. 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
60
what is correction of a sagittal plane extra-articular deformity b a corrective osteotomy prior to TKA indicated
generally when greater than 20° recurvatum or procurvatum is present
61
What are general considerations and preparation in revision TKA?
[Instr Course Lect. 2014; 63:239-51]
1. Rule out infection
* a.History, physical, bloodwork (CBC, ESR, CRP), joint aspiration
2. Previous OR note
* a.Implants
* b.Approach
* c.Complications
3.Radiographs
* a.AP, lateral and full length standing
* b.Previous radiographs for comparison
4. Determine revision implants
* a.Stems, augments, cones/sleeves, unconstrained, varus/valgus constrained, hinged, endoprosthesis
5. Surgical steps
* See Separate Flashcard
62
What are the surgical Steps for Revision TKA?
A.Skin incision
* i.Most lateral skin incision
* ii.Skin bridges \>6cm
* iii.Avoid crossing previous incisions at angles \<60°
* iv.Cross transverse incisions perpendicular
B. Approach
* i.Medial parapatellar preferred
* 1.Generous release of the medial tibia to facilitate external rotation
* 2.Release the medial and lateral gutters of scar tissue
* 3.Release scar tissue between patellar tendon proximal tibia
* ii.`If difficult exposure
* 1.Quadriceps snip (in medial, out lateral at 45def)
* 2.Tibial tubercle osteotomy
* a.Can assist with tibial stem removal
* b.Medial to lateral, 5-8cm in length with 1cm bone bridge proximally, tapered distally, lateral soft tissue left intact to allow osteotomy to hinge open
* c.Fixation at end of procedure with wire loops around fragment
* 3.V-Y turndown
C. Poly liner removal
* Osteotome
* Drill, cancellous screw
D. Femoral component removal
* Oscillating saw and straight or curved osteotome used at implant-cement interface
* Punch and mallet
E. Tibial component removal
* i.Oscillating saw and straight osteotomes
* ii.Punch and mallet or stacked osteotomes to disengage tibial tray
* iii.Specialized extraction tools may be necessary
F. .Femoral or tibial stem removal
* i.If stem loose ensure if cemented that the bulk of the cement does not cause fracture with extraction (fracture cement mantle first)
* ii.If stem well fixed an anterior cortical trough can be created to debond – bypass with stem with revision
G.Cement removal
* i.Complete removal in septic cases; in aseptic cases well fixed cement may be left
* ii.Osteotomes, crochet hooks, burr, cement splitters
H.Patellar component removal
* i.Cemented poly buttons – use oscillating saw at cement-poly interface, cut through pegs and burr out pegs
* ii.Uncemented button – oscillating saw and metal cutting wheels to cut pegs
I.Sequence of reconstruction
* i.Rebuild the tibial platform
* ii.Measure the flexion and extension spaces and reconstruct the femur to equally fill those spaces
* iii. Implant selection depends on bone loss and ligamentous stability
* 1. Bone defects
* A. \<5mm - cement alone
* B. 5-10mm - cement and screw, bone graft, metal augments
* C. \>10mm - metal augments
* D. Massive bone loss - cones, sleeves, structural allograft
* 2.Ligamentous instability
* A.Unconstrained – collaterals intact
* B.Varus/valgus constrained – single collateral compromised
* C.Hinged prosthesis – global instability, severe bone loss or deformity, flexion extension mismatch
* 3.Stems
* A. Generally required unless primary components used
* B. Uncemented vs cemented
63
What is the preoperative workup of a suspected PJI?
[IDSA guidelines]
1. History
* Acute onset of pain
* Chronic pain since surgery
* Wound healing problems, drainage, superficial or deep infection
* Systemic symptoms (fever, chills, etc.)
* Prior surgeries on affected joint
2. Physical exam
* Swelling, Erythema, Drainage, Sinus tract
3. Obtain OR note for date and type of implants
4. ESR/CRP
5. Blood culture if fever or acute onset of symptoms
6. Radiographs
7. Joint arthrocentesis
* Cell count, cell differential, gram stain, culture and sensitivity, crystals
64
What is the treatment for acute infected prosthesis (TKA/THA)
(\<30 days postop or \<3 weeks of symptoms from hematogenous infection):
Single Stage Revision
1. DAIR – debridement, antibiotics, irrigation and retention of implants
* A. Utilize previous approach
* B. Multiple tissue samples for culture (3-6)
* C. Extensive debridement of all devitalized soft tissue and bone
* D. Synovectomy
* E. Exchange of modular components
* i. Liner, modular head
* F. Low pressure irrigation (6-9L)
2. Administration of 6 weeks of IV antibiotics
* Possible 3-6 months of oral antibiotics following
65
What is the management of chronic infected prosthesis (TKA/THA)?
2 Stage Revision:
1. First stage
* A. Utilize previous approach
* B. Remove all implants
* C. Multiple tissue samples for culture (3-6)
* D. Extensive debridement of all devitalized soft tissue and bone
* E. Synovectomy
* F. Reaming of intramedullary canals
* G. Low pressure irrigation (6-9L)
* H. Insert static or dynamic antibiotic spacer dependent on patient factors (soft tissue, bone loss, previous failed dynamic spacer)
2. Administration of 6-8 weeks of IV antibiotics based on sensitivities (consult ID)
* Consider 3-4 months if immunocompromised, poor soft tissue coverage, sinus tract or virulent organism
* 2 week antibiotic holiday prior to proceeding to second stage
* i. ESR/CRP remain stable and no clinical signs of infection
3. Second stage
* A. Remove antibiotic cement spacer
* B. Send tissue for frozen section
* i. If \<5 PMNs per high powered field for all specimens proceed with second stage
* ii. If \>5 PMNs per high powered field for any specimen repeat first stage
* C. Irrigation and debridement
* D. Reconstruction with revision components
4. Administration of antibiotics until cultures negative
66
What are the risk factors for PJI in TKA?
[JAAOS 2015;23:356-364]
1.Preoperative
* a.Malnutrition
* b.Diabetes
* c.Obesity
* d.Male
* e.Posttraumatic arthritis
* f.Inflammatory arthritis
* g.Colonization with MRSA
* h.Prophylactic antibiotics
2.Intraoperative
* a.Skin prep
* b.Longer surgical time
* c.Antibiotic impregnated cement
* d.OR configuration and traffic
* e.Wound closure
* f.Frequent glove changes
3. Postoperative
* a.Retention of foley catheter \>1 day
* b.Blood transfusions
* c.Prolonged wound drainage
* d.Dental procedures
67
What is the 2018 Definition of PJI?
[MSIS/Parvizi - The Journal of Arthroplasty 33 (2018) 1309e1314]
1.Major Criteria
* Two positive cultures of the same organism
* Sinus tract with evidence of communication to the joint or visualization of the prosthesis
* DECISION
* At least one of the following = infected
2.Minor Criteria
* SERUM
* Elevated CRP OR D-Dimer - Score 2
* Elevated ESR - Score 1
* SYNOVIAL
* Elevated synovial WBC count or LE - Score 3
* Positive alpha-defensin - Score 3
* Elevated synovial PMN% (>80%)- Score 2
* Elevated synovial CRP (>6.9) - Score 1
* DECISION
* ≥6 = infected
* 2-5 = possibly infected
* For patients with inconclusive minor criteria, operative criteria can also be used to fulfill definition for PJI.
* 0-1 = not infected
3. Inconclusive preop score OR dry tap
* Positive histology - Score 3
* Positive purulence - Score 3
* Single positive culture - Score 2
* DECISION
* ≥6 = infected
* 4-5 = inconclusive
* Consider further molecular diagnostics such as next-generation sequencing
* ≤3 = not infected
## Footnote
MSIS criteria parameters
ESR >30, CRP >10
synovial leukocyte count >1100 for knees, > 3000 for hips
PMN% >64% for knees, >80% for hips
68
Describe a two-stage revision for PJI?
[JAAOS 2014;22:153-164]
1.First stage
* a.Removal all implants and foreign material
* b.Extensive debridement
* i.All nonviable soft tissues and bone, synovectomy, irrigation, and reaming of the medullary canals
* c.Antibiotic cement spacer
* d.Antibiotics
2.Second stage
* a.Performed once antibiotics complete, wound healed and infection eradicated
* b. Remove antibiotic cement spacer
* c. Irrigation and debridement
* d. Reconstruction with revision components
69
What considerations must be taken for antibiotic cement?
[JAAOS 2014;22:153-164]
1. Commercially available antibiotic cement is meant for prophylaxis not active infection (inadequate dose)
2. Antibiotics added to cement must have the following features:
* a.Water soluble
* b.Thermodynamically (heat) stable [vanco, gentamycin, tobramycin]
* c.Bactericidal
* d.Released gradually over an appropriate period of time
* e.Evoke minimal local inflammatory reaction
* f. Selected based on likely pathogens and culture sensitivites
70
What are the reported dose ranges per 40g bag of bone cement for gentamicin, tobramycin and vancomycin?
[JAAOS 2014;22:153-164]
1. Gentamicin = 2-5g
2. Tobramycin = 2.4-9.6g
3. Vancomycin = 3-9g
Target 3g vanco and/or 3.6g tobramycin in 40g cement
* Vanco = 1g/vial, Tobra = 1.2g/vial
71
What are options available for knee cement spacers?
[JAAOS 2014;22:153-164]
1.Static cement spacer
* a.Rush rods placed through the cement into the intramedullary canal of the femur and tibia
* b.Advantages – preserves joint space, provides initial stability, period of soft tissue rest
2.Dynamic cement spacer
* a.Cement on cement
* b.Cement on poly
* c.Metal on poly
* i.Advantages – custom antibiotics, accurate component sizing, improved wear, improved function between first and second stage
* d.Advantages – similar infection eradication rates compared to static, higher ROM and knee function scores
72
What is the recommended antibiotic course after the first stage?
[JAAOS 2014;22:153-164]
1. 6-8 weeks of IV antibiotics
2. Consider 3-4 months if:
* a.Immunocompromised
* b.Large draining sinus present
* c.Poor soft tissue envelope
* d.Virulent organism (eg. MRSA)
3. 2 weeks prior to second stage antibiotics are held (‘antibiotic holiday’)
73
When is it safe to proceed with the second stage reimplantation?
[JAAOS 2014;22:153-164]
1.ESR and CRP decline
* a.Do not have to return to normal, no cutoff values
* b.Remain down after antibiotic holiday
2.Absence of clinical signs of infection
74
At the time of second stage reimplantation what is the role of frozen section analysis?
[JAAOS 2014;22:153-164]
1. If frozen section \>5PMNs per high powered field for any specimen = infected
* a.Repeat first stage
2. If frozen section \<5 PMNs per high powered field = not infected
* a.Proceed to reimplantation
75
When can a I&D and liner exchange be considered?
[Infect Dis Clin N Am 31 (2017) 237–252][IDSA guidelines]
1. Hematogenous infection with <3 weeks of symptoms
2. Early postoperative infection <30 days after surgery
