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Flashcards in Arthroplasty Deck (106)
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1

Options for this young (<50yo) patient with a painful right knee

  • Exhaust concervative treatment
    • PT, NSAIDS
    • off loading brace
    • Cortisone injections
  • Valgus producing tibial ostotomy 
    • Contraindications
      • Inflammatory arthritis
      • Less than 90 deg flexion
      • Flexion contracture > 10 deg
      • Ligament instability (varus thrust)
      • Lateral tibial subluxation > 1cm
      • Medial compartment bone loss
      • Lateral compartment joint space narrowing
    • Predictors of failure
      • Smoking
      • > 60
      • Varus > 10
      • Other arthritides
  • Closing wedge problems
    • Patella baja
    • Loss of posterior slope
  • Opening wedge
    • Nonunion
    • Loss of valgus correction

2

Contraindications to HTO

Inflammatory arthritis
Less than 90 deg flexion
Flexion contracture > 10 deg
Ligament instability (varus thrust)
Lateral tibial subluxation > 1cm
Medial compartment bone loss
Lateral compartment joint space narrowing

3

Predictors of failure of HTO

Smoking
> 60
Varus > 10
Other arthritides

4

Options for this 65yo male with painful right knee?

  • Exhuast non-operative
    • ​PT, NSAIDS
    • cortisone injection
    • offloading brace
    • Cane, mobility aids
  • UKA vs HTO vs TKA
  • UKA benefit over HTO and TKA
    • Smaller incision
    • Better knee function
    • Shorter stay with less pain

  • Technique
    • Do not overcorrect - can cause early failure
    • Varus - correct to 1-5 deg of valgus
  • Contraindications
    • ACL deficiency (strongest)
    • fixed varus or valgus deformity > 10 degrees
    • restricted motion
      • < 90° of flexion
      • fixed flexion contracture of > 10°
    • joint subluxation of 5 mm or greater
    • arthrosis of the additional compartment
      • modest Outerbridge Stage II chondromalcia of patella is acceptable
    • non-osteoarthritis arthritis
    • younger high activity patients and heavy laborers
    • overweight patients (> 90 kg)
  • Selection criteria
    • Pain must be localized to the compartment being replaced
    • Anterior knee pain means patellofemoral disease
    • Global pain means tricompartmental disease
  • Complications
    • Stress fractures
      • best visualized on bone scan
      • Usually on the tibial side
    • Tibial component collapse
      • poor mechanical properties of the bone
    • Failure
      • Overcorreciton
  • Undercorrection
  • Fixed-bearing (loosening)
  • Mobile bearing (diseae progression)
  • Patellar impingment (requires revision to TKA)

5

Normal alignment of the knee

Lateral proximal femoral angle: 90 degrees

Mechanical Lateral distal femoral angle: 88 degrees

Anatomic Lateral distal femoral angle: 81 degrees

Medial proximal tibial angle: 87 degrees
Lateral distal tibial angle: 89 degrees

 

6

What is this depicting and what are your considerations when measuring the deformity?

CORA - center of rotation of angulation

  • Draw a line threw the axis of the distal and proximal end
  • If there is only angulation - will occur at the apex of deformity
  • If there is combined translation - will occur at a distance equal to the amount of translation deformity
  • If angulation is seen on both AP and lateral, the true angulation will be larger than that seen on either XR
  • When you don't see angulation in one plane, but you do on the other - this is the true angular deformity

7

What is your appraoch to this patient?

  • History
    • Take a complete and ample history
    • Pain, functional issues, issues in other joints
    • Previous surgeries, trauma
    • PMHx, meds, all
  • Physical
    • Look
      • Gait, measure alignment and deformity
    • Feel
      • Assess stability of the hip, knee, ankle/foot
    • Move
      • ROM, contractures
    • Full NV exam
  • Imaging
    • Radiographs - full length standing AP/Lat
  • Indications for surgery
    • Ligamentous laxity on the concave side
    • LLD > 2cm
    • Uniconylar OA of the knee
    • Inability to place the foot in a plantigrade position
  • Conservative
    • Unloading brace
    • Shoe lift/orthoses
    • Appropriate analgesia
  • Considerations
    • Healing potential
      • Should be done in an area with better healing potential
      • Can accept some translation as long as the deformity is anticipated
    • Leg length discrepancy - affected by both closing/opening and varus/valgus, the affect is combined
    • Closing wedge can relatively lengthen ligaments and tendons
    • Opening wedge with lengthen = half the base of the triangle
  • Varus correction will produce lengthening
    • This will decrease as you go more distal
  • Valgus produces shortening​

8

Technical goals of TKA

  • restore mechanical alignment (mechanical alignment of 0°)
  • restore joint line ( allows proper function of preserved ligaments. e.g., pcl)
  • balanced ligaments (correct flexion and extension gaps)
  • maintain normal Q angle (ensures proper patellar femoral tacking)

9

You are planning a TKA for this patient. What are the order of releases

  • osteophytes
  • deep MCL  (usually osteophytes and deep MCL is sufficient release)
  • Posteromedial corner
    • Semimembranosus
    • capsule
    • superfical MCL
      • can find as it blends into pes anserine complex
      • can not completely release or will have valgus instability (requires constrained prosthesis). Therefore perform subperiosteal elevation only
      • Differential release: performed with two component of superficial MCL
        • posterior oblique portion is tight in extension (release if tight in extension)
        • anterior portion is tight in flexion (release if tight in flexion)
  • PCL

10

Order of release for a flexion contracture

  • Order of posterior release
    • osteophytes
    • posterior capsule
    • gastronemius muscles (medial and lateral)
  • You do not want to address by removing too much tibia
  • will change joint line and lead to patella alta
  • Performed with the knee flexed so there is less risk to the popliteal artery

11

Important considerations for planning your TKA cuts

Femur

  • uses intramedullary guide, if can't get this then use CT guided (post DFVO, trauma etc)
  • Distal femur valgus cut (5-7° from AAF )
    • jig measures 6 degrees from femoral guide (anatomic axis)
    • will vary if people are very tall (VCA < 5°) or very short (VCA > 7°)
  • Posterior referencing with femoral cut
    • 3 deg ER (normal DR is 3 deg IR)
    • otherwise will internally rotate your component
    • should be parallel to interchondylar axis 
    • be careful with hypoplasia of the lateral femoral condyle, you can put the prosthesis into IR with a posterior reference system

Tibia

  • Cut should be perpendicular to mechanical axis
  • Can use intramedullary, unless there is deformity then need to use extramedullary

12

This patient comes in with knee pain. What is the most common complications of TKA?  How can you prevent it?

  • Abnormal patellar tracking, although not the most serious, is the most common complication of TKA.
  • The most important variable in proper patellar tracking is preservation of a normal Q angle (11 +/- 7°)
    • the Q angle is defined as angle between axis of extensor mechanism (ASIS to center of patella) and axis of patellar tendon(center of patella to tibial tuberosity)
  • Any increase in the Q angle will lead to increased lateral subluxation forces on the patella relative to the trochlear groove, which can lead to pain and mechanical symptoms, accelerated wear, and even dislocation.
  • Common errors include:
    • internal rotation of the femoral prosthesis
    • medialization of the femoral component
    • internal rotation of the tibial prosthesis
    • placing the patellar prosthesis lateral on the patella

13

Where should the joint line be in TKA?   What problems can you run into if you move it

  • Normal joint line
    • 1 cm above fibula
    • ​​2 fingerbreaths about tibial tuberosity
  • elevating the joint line (> 8mm leads to motion problems) and can lead to
    • mid-flexion instability
    • patellofemoral tracking problems
    • an "equivalent" to patella baja
  • lowering joint line
    • lack of full extension
    • flexion instability

14

Saggital balancing.  Go. All of it. You have 30 sec.

15

You are planning a TKA on this patient.  What is your order of release.  What are some important considerations?

  • Classification
    • Stage 1 - not correctable
    • Stage 2 - > 10 deg, not correctable
    • Stage 3 - severe deformity, possibly incompetent MCL, severe bone loss
  • Order of Release
    • osteophytes
    • lateral capsule
    • iliotibial band if tight in extension (release if tight in extension)
      • with Z-plasy or release off Gerdy's tubercle
    • popliteus if tight in flexion (release if tight in flexion
    • for severe deformities release both the iliotibial band and the popliteus
    • LCL  
      • some authors prefer to release this structure first if tight in both flexion and extension
      • others prefer this should be the last structure to release, if you need to release it consider of constrained prosthesis
  • Considerations
    • ​Coronal balancing - older patient can use CCK, younger patient want to take less bone, but still want to do a primary knee
    • peroneal nerve palsy

16

You do a TKA on this patient and surprise! He gets a peronal nerve palsy.  What are some risk factors? How do you treat?

 

  • Prognosis
    • most resovle in 3 months
  • Risk Factors
    •  use of epidural anesthesia; 
    •  previous spinal surgery (double crush); 
    •  valgus knee deformity 
    •  flexion contracture more than 20 deg
    • abarent retractors
    • pre-op neuropathy
  • Immediate
    • take of dressing
    • flex the knee
    • throrough documentation of physical exam
  • Post-op
    • AFO
    • PT for ROM
    • EMG with-in one month
  • At 3 months
    • Repeat EMG for improvement
    • Decompression with neuroloysis
      • 4 cm proximal 
      • adherence to fibular head
      • 7-15 cm distal to fibular head

17

Amount of antibiotics to put in antibiotic cement

  • Need to keep under 2g/40g of cement to preserve mechanical function
  • Safe loading dose
    • Vanco - 10.5g
    • Gent - 12.5g (although some report lower - 2g)
  • Masri recommends 3.6g tobra and 1g vanc per 40 mg
  • Powder is poured into liquid cement, vacum is not used - keeps porosity high to help with elution of cement

18

What's the most important factor in post-op TKA ROM?

Pre-op ROM

19

Pros and Cons of a CR knee 

  • Most common, relies on native PCL
  • Bone conserving
  • More consistent joint line preservation
  • Proprioceptive feedback
  • Disadvantages
    • Loss of PCL will lead to instability and failure
      • Tight PCL will cause tightness in flexion and cause lift-off of component
      • Excessive resection will cause failure from repetitive subluxation
      • Instability, pain, buckling
    • Harder to balance
      • Avoid in varus > 10, valgus > 15
    • PCL Rupture
      • Trauma
      • Osteolysis
    • Paradoxical movement - due to loss of ACL
      • Tibia slides forward under the femur instead of posteriorly
        Modern implants move center of rotation more posterior

20

Pros and cons of anteriorly stabilized knee

  • Anterior lip prevents femor from rolling forward
  • PE is highly congruent, there is no cam
  • Advantage
    • Bone conserving
    • Easier balancing
    • Operative versatility
    • Regulated kinematics
  • Disadvantage
    • Increased PE surface
    • Minimal rollback
    • Flexion gap laxity = instability and pain - requires treatment to assess this

21

Indications, pros and cons of a PS knee

  • Outcomes are the same for PS and CR knee
  • Indications
    • Previous patellectomy - weak extensor mechanism can lead to anterior dislocation
    • Inflammatory arthritis - leads to PCL rupture
    • varus >10
    • valgus >15
  • Advantages
    • Easier balancing
    • No sliding
    • better flexion
  • Disadvantages
    • Cam jump - if flexion gap is loose, knee will hyperextend, rotate and jump over post and dislocate
      • Reduce with sedation, 90 deg of flexion and anterior drawer maneuver
      • Avoid in knees with >130 flexion
      • Ultimately needs to be revised to address loose flexion gap
        • Overreleased poplitues with saw blade
        • Overrelease anterior MCL
        • Anterior translation femoral component
    • Patella Clunk
      • Scar tissue superior to patella gets cause in box
      • Flexion - Ex at 45 deg
      • Treatment - arthroscopic or mini open debridement
    • PE Wear from tibial post
      • Causes aseptic loosening
      • If need if hyperextended will cause impingement anteriorly and increase wear rate
      • Flexed femoral component, excess tibial slope, anterior translation
    • Additional bone removed
      • For post
      • Large flexion gap
        • Due to PCL removable
        • Need to take more distal femur to account for this
  • Beware joint line elevation with patella baja** Max 8mm 

22

Indications for the use of this prosthesis?

  • LCL/MCL attenuation or deficiency
  • Flexion gap laxity
  • *Can be used more in revision TKA, but consider at times for primary
    • ie; severe valgus knee

the patient depicted had instability following CR knee and PCL rupture

 

23

Indications for the following prosthesis

Constrained hinge with rotating platform

  • Tibia rotates with-in yoke to allow rotation during gait
    • Without rotation there was a high loosening rate
    • Intramedullary stem for high rotational loads
  • Indications
    • Global ligament deficiency
    • Hyperextension instability (polio or tumor resection)
    • Knee resection for tumor
    • Complete MCL (controversial)

24

Why was this prosthesis choosen?

Tumour Prosthesis

  • tumour
  • significant bone loss

25

You do this procedure on a healthy 65 yo male.  What are all the complications?

  • Femoral Notching
    • Jig is placed too low on the femur
    • Lowers load to failure (fracture)
    • In bending the fracture extend from the notch creating an oblique fracture
  • Peroneal Nerve Palsy
  • PCL deficiency  (in a CR knee)
    • Will become loose in flexion, knee will feel unstable and femur will start to slide forward
    • Will get anterior knee pain
    • Treat with revision to PC or CCK
  • Lateral Retinacular Release
  • Patella Fracture
  • Intra-operative MCL injury
    • Primary repair with 6 weeks NWB with full ROM (if young)
    • Recommended treatment is to covert to highly constrained prosthesis
  • Arthrofibrosis
  • Post-op Flexion Contracture
    • The most important factor of post-op range of motion is pre-op ROM
    • In a well balanced knee the gastroc is the cause of the flexion contracture
  • Severe extra-articular femoral deformity
    • Can do a combined osteotomy with TKA with long stem that goes past the osteotomy site
  • Osteolysis
    • Usually around 8-10 years
    • Gradual increase in effusion with mild warmth but no erythema
    • Normal lab results and aspiration
    • Most common place is the posterior femoral condyle

26

What is usually causing a flexion contracture post-op TKA

gastroc

27

When do you usually see osteolysis in TKA and where do you get it?

8-10 years

posterior femoral condyle

28

You do the following procedure.  They come back at 6 weeks and a stiff knee.  How do you approach this?

  • Functional ROM
    • 90 degrees needed to go down stairs
    • 95 to get up from a chair
  • Factors to assess
    • Boney resection
    • patella baja/elevation of joint line
    • tibial slope (not enought)
    • posterior osteophytes
    • patient factors
  • Radiography
    • Assess joint line based on fibula and patella
    • Assess alignment of implants
    • presence of osteophytes
  • Treatment
    • depends on the surgeon, some will take them back if not to 90 by 6 weeks, can be done up to a year
    • Manipulation
      • usually at 6 weeks
      • Later manipulation as high rate of fracture
    • Scope
      • release adhesions, cement/loose bodies
    • Arthrotomy 
      • poly exchange, patellar exchange, posterior release, tuberosity transfer, quads snip
      • Not highly recommended, often fails with recurrent pain and stiffness
    • Revision TKA
      • tibial tuberosity osteotomy, V-Y plasty
      • address tibial slope, patellar height

29

TKA.  Patient can no longer extend their knee.  How do you approach this?

  • Can also occur with lowering of the joint line
  • Overview
    • patellar tendon rupture is a rare and devastating complication after TKA with an incidence reported ranging from 0.17% to 2.5%
    • Quadriceps tendon rupture extremely rare ~1%.
      • Higher risk with infection, multiple surgeries, hinged prosthesis
    • Patellar Fracture
      • Thickness <12mm
      • Lateral retinacular release (osteonecrosis)
        • Due to transection of superior genicular artery
      • Osteonecrosis
        • Theoretical risk with removal of fat pad, lateral release, quads turndown
        • Blood supply comes from the medial to lateral part of the knee
    • Can also be caused by maltracking or direct trauma
  • Quads or patellar tendon rupture
    • Overall very poor outcome
  • Treatment
    • Can treat conservatively if the component is solid and there is no extensor lag
    • Quads
      • Drill holes if no patella resurfacing
      • Suture anchors if there is less bone stalk
    • Patellar
      • Primary repair with drill holes or suture anchor does not do well
      • Component revision if there is enough bone, component resection if not
      • Allograft or autograft if there is significant extensor lag
      • Fresh frozen is the prefered choice
    • Use a detensioning wire (or mersiline tape) for 3 months

30

Considerations when deciding whether to resurface the patella

  • High clinical variability in practice
  • Complications 
    • patellar fracture
    • malailignment
  • Consequences
    • Anterior knee pain with higher revision rate
    • 50% re-operation rates and higher complication rates with no patellar resurfacing - at about 5 years outcomes become the same
  • Earlier designs had a high failure rate, newer designs have longer survivorship
  • Technique
    • Indicaitons to resurface
      • maliagnmnet
      • minimal wear
      • inflammatory disease
    • If you're not resurfacing use a more anatomic design
    • Patellar cut
      • Use the caliper before and after
      • Under resection leads to pain and a tight compartment
    • Over resection leads to fracture - max thinness is 12mm
    • Medial-superior placement is ideal
      • Helps to restore Q angle with fewer tracking complications
    • Lateral Release
    • complications
      • fracture
      • component dislocation
      • wear
      • infection