Knee — FRCS Quiz

27 slides

▸ Slide 159 · KneeKnee · 2 questions expand

Question list

Q1-Q22 questions — tap to reveal all answerslist

What knee topic does this slide cover?
What are the key learning points of this knee slide?

Answers · Q & A

Q1.What knee topic does this slide cover?

Not covered in the speaker notes

Q2.What are the key learning points of this knee slide?

Not covered in the speaker notes

▸ Slide 160 · Goal and principle - TKRKnee · 2 questions expand

Question list

Q1-Q22 questions — tap to reveal all answerslist

What is the goal of total knee replacement (TKR)?
What are the principles of TKR?

Answers · Q & A

Q1.What is the goal of total knee replacement (TKR)?

Painless, stable, mobile joint free of infection

Q2.What are the principles of TKR?

Restore mechanical axis
Restore joint line
Balanced F/E gaps
Stable fixation

▸ Slide 161 · OA Knee non OPKnee · 6 questions expand

Question list

Q1-Q66 questions — tap to reveal all answerslist

What does the AAOS 2021 guideline strongly recommend for knee OA?
What does the AAOS 2021 guideline say about weight loss, HTO and IA steroid in knee OA?
What does the AAOS 2021 guideline say CANNOT be recommended for knee OA?
What is the guideline evidence on intra-articular hyaluronic acid injection for knee OA?
What did the 2022 BMJ Pereira meta-analysis conclude about viscosupplementation?
What is the evidence for oral viscosupplementation?

Answers · Q & A

Q1.What does the AAOS 2021 guideline strongly recommend for knee OA?

Rehabilitation, education and wellness activities (strong)
NSAID (strong)

Q2.What does the AAOS 2021 guideline say about weight loss, HTO and IA steroid in knee OA?

Weight loss - moderate
HTO - limited
IA steroid is listed on the slide (grade not clearly stated)

Q3.What does the AAOS 2021 guideline say CANNOT be recommended for knee OA?

Acupuncture
Viscosupplement
Glucosamine
Arthroscopic lavage
IA HA

Q4.What is the guideline evidence on intra-articular hyaluronic acid injection for knee OA?

AAOS 2021: cannot recommend
NICE 2014: cannot recommend
ACR 2012: may recommend (2020 ACR recommends against)
EULAR 2020: may recommend
AMSSM: can use in KL grade II or III

Q5.What did the 2022 BMJ Pereira meta-analysis conclude about viscosupplementation?

Small reduction in knee OA pain compared with placebo
Difference is less than the clinically important difference
Does NOT support broad use of viscosupplementation

Q6.What is the evidence for oral viscosupplementation?

BMJ 2010 Wandel meta-analysis: no evidence

▸ Slide 162 · Kellgren Lawrence Grading ScaleKnee · 4 questions 1 check expand

Question list

Q1-Q44 questions — tap to reveal all answerslist

What are the Kellgren-Lawrence grades for knee OA?
What are the **Xray** classification criteria for OA at each Kellgren-Lawrence grade, as printed on the slide?
What radiographic finding defines Kellgren-Lawrence grade 4?
How is joint space reduction used in Kellgren-Lawrence grading?

Answers · Q & A

Q1.What are the Kellgren-Lawrence grades for knee OA?

Grade 0: normal appearances
Grade 1: osteophytes with normal joint space
Grade 2: less than 50% joint space reduction
Grade 3: more than 50% joint space reduction
Grade 4: bone-on-bone contact

Q2.What are the Xray classification criteria for OA at each Kellgren-Lawrence grade, as printed on the slide?

Grade1: doubtful narrowing and possible osteophytic lipping
Grade2: definite osteophytes, definite narrowing
Grade3: moderate multiple osteophytes (slide wording: 'osterophyte'), definite narrowing, some sclerosis and possible deformity
Grade4: large osteophytes, marked narrowing, severe sclerosis and definite deformity

Q3.What radiographic finding defines Kellgren-Lawrence grade 4?

Bone-on-bone contact
Slide criteria: large osteophytes, marked narrowing, severe sclerosis and definite deformity

Q4.How is joint space reduction used in Kellgren-Lawrence grading?

Grade 2 = less than 50% joint space reduction
Grade 3 = more than 50% joint space reduction

Fact check

Kellgren-Lawrence grade 1 = osteophytes with normal joint space; grades 2/3 defined by 50% joint space reduction — non-standard definitions — Original KL: grade 1 doubtful joint space narrowing with possible osteophytes; grade 2 definite osteophytes with possible narrowing; grade 3 definite narrowing with moderate osteophytes; grade 4 marked narrowing with sclerosis and bone end deformity — source

▸ Slide 163 · Choice of implant in TKRKnee · 12 questions 1 check expand

Question list

Q1-Q1212 questions — tap to reveal all answerslist

What factors determine the choice of implant in TKR?
How are TKR implants classified by constraint?
What is a non-hinged constrained prosthesis?
What are the pros and cons of a mobile bearing in TKR?
What are the features of an all-polyethylene tibial component?
What surgical approaches are used in TKR?
How do you correct gap imbalance in TKR?
What are the problems of patellar resurfacing versus non-resurfacing in TKR?
What is the evidence on routine patellar resurfacing in TKR?
How do you reduce transfusion in TKR?
What alignment deviation is acceptable in TKR?
What is the evidence on single stage versus sequential bilateral TKR?

Answers · Q & A

Q1.What factors determine the choice of implant in TKR?

Constraint
Modularity of the tibial component
Bearing fixation
Type of PE insert
Cemented vs cementless
+/- patella

Q2.How are TKR implants classified by constraint?

Unconstrained: CR, P sacrificing, P stabilise (substitute)
Constrained: non-hinged / hinged (or rotating hinge)
Also fixed vs mobile bearing; metal back vs all PE

Q3.What is a non-hinged constrained prosthesis?

A constrained prosthesis without an axle connecting the tibial and femoral components
Used in soft tissue / bony defect
Increased stability but more stress on the interface

Q4.What are the pros and cons of a mobile bearing in TKR?

No benefit proven
Pros: theoretically increased contact area leading to less wear; theoretically replicates native knee kinematics
Cons: spinout, more back side wear
Used in hinged implants

Q5.What are the features of an all-polyethylene tibial component?

Cheaper
Less modular

Q6.What surgical approaches are used in TKR?

Medial parapatellar - extensile; patella perfusion impaired if lateral release needed
Lateral parapatellar - direct access to lateral structures; difficulties in everting patella
Smaller exposure: midvastus, subvastus
Larger exposure: quadriceps snip, VY / osteotomy

Q7.How do you correct gap imbalance in TKR?

Tight in flexion and extension: decrease PE insert size, resect more proximal tibia
Tight in extension only: resect additional distal femur, posterior capsular release
Tight in flexion only: downsize femoral component, recess/release PCL, increase posterior tibial slope, release posterior capsule

Q8.What are the problems of patellar resurfacing versus non-resurfacing in TKR?

Resurfacing: fracture, loosening, clunk, AVN
Not resurfacing: residual quads weakness (poor moment arm, patellar height not restored), maltracking, residual anterior knee pain

Q9.What is the evidence on routine patellar resurfacing in TKR?

Zmistowski (Rothman) J Arthroplasty 2019: should NOT routinely replace the patella
Teel J Arthroplasty 2019 meta-analysis: function no difference, non-resurfacing = more reoperations

Q10.How do you reduce transfusion in TKR?

Pre-op: correct coagulopathy, stop medications, correct anaemia
Intra-op: normovolaemic haemodilution, permissive hypotension, transamin, tourniquet, bone wax
Cell saver for revision cases
Post-op: transamin, no drain

Q11.What alignment deviation is acceptable in TKR?

Accept 3 degrees deviation
Outliers have poor results

Q12.What is the evidence on single stage versus sequential bilateral TKR?

Local AHNH study: no outcome difference; backed by Denmark group 2015 KSSTA Lindberg-Larsen
J Arthroplasty 2019 David Ward: simultaneous BTKA had significantly increased odds of multiple complications vs staged BTKA, but the absolute risk differences are minimal and complications are uncommon
Stanford J Arthroplasty 2022: simultaneous TKR increases the risk of establishing the second knee outside the mechanical neutral

Fact check

Zmistowski from Rothman Institute J Arthroplasty 2019 prospective RCT shows patella should not routinely be replaced — mischaracterised study design — It is a cost-utility analysis of 14 prospective RCTs, not itself an RCT; it concludes routine resurfacing of arthritis-free patellae is not cost-effective — source

▸ Slide 164 · CR vs PS TKRKnee · 7 questions expand

Question list

Q1-Q77 questions — tap to reveal all answerslist

What is roll back in the knee?
What are the prerequisites for CR TKR?
What are the advantages of CR TKR?
What are the disadvantages of CR TKR?
What are the advantages of PS TKR?
What are the disadvantages of PS TKR?
What is the evidence comparing CR and PS TKR?

Answers · Q & A

Q1.What is roll back in the knee?

Posterior translation of the femur with progressive flexion

Q2.What are the prerequisites for CR TKR?

PCL intact
Varus/valgus <15 degrees

Q3.What are the advantages of CR TKR?

PCL gives better proprioception
Femoral roll back - better ROM and improved lever arm for the quadriceps
PCL absorbs the AP and varus-valgus strain otherwise transferred to the bone-prosthesis interface
Preserves bone stock
Preserves the joint line

Q4.What are the disadvantages of CR TKR?

Increased shearing + delamination leading to PE wear
Technically more difficult (poorer exposure, gap balancing, see –saw effect if flexion and extension gaps are both too tight)
Paradoxical roll forward if the PCL is defunctioned

Q5.What are the advantages of PS TKR?

More conformity so less PE wear (delamination, pitting, fatigue)
Does not rely on the PCL for roll back
Technically easier

Q6.What are the disadvantages of PS TKR?

More constraint - more stress at the bone-implant interface
More bone loss
Dislocation (cam jump)
Patellar clunk - superior patellar scar caught in the box in extension
Reduce ROM: cut PCL -> looser flexion gap -> thicker PE -> cut more distal femur -> elevate joint line -> patella baja

Q7.What is the evidence comparing CR and PS TKR?

ROM similar
Proprioception similar
Australian joint registry 2021: PS 7.5% vs CR 6.1% revision at 15 years

▸ Slide 165 · Xray of patients knee early post op after total knee replacementKnee · 3 questions expand

Question list

Q1-Q33 questions — tap to reveal all answerslist

Describe the radiographic findings in this early post op TKR X-ray.
What further imaging or measurements would you like after TKR?
What is checked on the lateral view of a post-TKR knee?

Answers · Q & A

Q1.Describe the radiographic findings in this early post op TKR X-ray.

This is an early post op film: both femoral and tibial implants are fixed with cement, no wedge/stem
Patella replaced
Femoral component size small, not flushed with the condyle, no notching on lateral view
Tibial implant size optimal, no overhang

Q2.What further imaging or measurements would you like after TKR?

Measure PE thickness
Long standing film for alignment

Q3.What is checked on the lateral view of a post-TKR knee?

Notching of the anterior femoral cortex
Femoral component sizing and flushness

▸ Slide 166 · How are u going to perform TKR in varus knee ?Knee · 11 questions expand

Question list

Q1-Q1111 questions — tap to reveal all answerslist

What does the pre-op X-ray show in this varus knee?
What are the problems to plan for when performing TKR in a varus knee?
What is the pre-op preparation for TKR in a varus knee?
What is the sequence of medial release in a varus knee TKR?
How do you manage a fixed flexion deformity in TKR?
What is the Anderson classification of bone defects in TKR?
How are contained and uncontained defects managed by size?
How is a tibial bone defect managed during TKR?
How is a femoral bone defect managed during TKR?
What are the pros and cons of bone grafting and the role of a long stem in TKR?
What are the post-op concerns and prophylaxis after TKR?

Answers · Q & A

Q1.What does the pre-op X-ray show in this varus knee?

Long standing and AP XR of the right knee showing a varus knee
Tibiofemoral angle 45degs
Medial tibia bone loss
Widening of lateral joint space
Tibia appears ER

Q2.What are the problems to plan for when performing TKR in a varus knee?

Soft tissue deficiency - plan extensive soft tissue release, constrained implant
Bony deficiency (contained/uncontained) - cement, cancellous graft, screw on cement, cortical graft, metal augment, tumour prosthesis
Alignment - pre-op standing scannogram to plan tibial/femoral cuts and guides (intramedullary, extramedullary or navigation)

Q3.What is the pre-op preparation for TKR in a varus knee?

Optimize patient fitness for operation
Prophylactic antibiotic
Same day admission to a clean ward
The most important pre-op part is planning (soft tissue, bony, alignment)

Q4.What is the sequence of medial release in a varus knee TKR?

Osteophyte
Medial joint capsule and deep MCL
PMC (capsule, semimembranosus, posterior oblique ligament)
Superficial MCL (subperiosteal release / pie crusting)
Pes anserius (pes anserinus)
Downsizing tibial side + removing uncapped part; if not balanced use a semi constrained implant (lateral epicondyle advancement / distalize fibular head)

Q5.How do you manage a fixed flexion deformity in TKR?

Extension gap tight, flexion gap normal
Post osteophyte --> post capsule
May cut more distal femur initially (e.g. 10mm vs normal 8mm)

Q6.What is the Anderson classification of bone defects in TKR?

1: does not affect stability
2: affects stability (metaphyseal damage) - cement, bone graft, metal wedge
3: deficient metaphysis affecting collateral/patellar tendon attachment - struct allograft, IBG, trabecular metal augment, tumour prosthesis

Q7.How are contained and uncontained defects managed by size?

Contained: <5mm cement; large defect cancellous bone graft
Uncontained: <5mm cement; 5mm-1cm bone graft/screw on cement; >1cm augment/strut graft + screw
Cannot use cement alone in a large defect (may crack)

Q8.How is a tibial bone defect managed during TKR?

Translate the tibial tray away from the defect
Resect the tibia at a lower level
Reassess the defect after the tibial cut: <5mm cement, 6-10mm bone graft, >10mm metal wedge

Q9.How is a femoral bone defect managed during TKR?

Affecting the chamfer cut - cement
Affecting the distal femur cut - metal augment
Massive bone loss - bone block / allograft

Q10.What are the pros and cons of bone grafting and the role of a long stem in TKR?

Bone graft replenishes bone stock but has donor morbidity
Young age tends to preserve bone stock
Use a long stem tibial component to share stress over the diaphysis (20% stress)

Q11.What are the post-op concerns and prophylaxis after TKR?

Chest infection, wound infection, UTI, DVT, knee stiffness
Post op: Early mobilization (early mobilisation), prophylactic antibiotics, wean off foley as early as possible
DVT: mechanical +/- medical prophylaxis (enoxaparin, pradaxa) in high risk group

▸ Slide 167Knee · 2 questions expand

Question list

Q1-Q22 questions — tap to reveal all answerslist

What topic is covered on this slide?
What assessment steps would you take for the knee condition shown on this slide?

Answers · Q & A

Q1.What topic is covered on this slide?

Not covered in the speaker notes

Q2.What assessment steps would you take for the knee condition shown on this slide?

Not covered in the speaker notes

▸ Slide 168 · Consent for TKRKnee · 5 questions expand

Question list

Q1-Q55 questions — tap to reveal all answerslist

What are the 90-day complication rates after primary TKR in the US Medicare population?
What are the 90-day complication rates after revision TKR?
What are the risks in the 90 days after discharge following TKR (JBJS 2006)?
What risks do you discuss when consenting for TKR?
Would you consider bilateral TKR in the same OT and why?

Answers · Q & A

Q1.What are the 90-day complication rates after primary TKR in the US Medicare population?

Source: JBJS 2005 (US Medicare population)
Mortality 0.7%
Readmission 0.9%
PE 0.8%
Wound infection 0.4%
Pneumonia 1.4%
MI 0.8%

Q2.What are the 90-day complication rates after revision TKR?

Mortality 1.1%
Readmission 4.7%
PE 0.5%
Wound infection 1.8%
Pneumonia 1.4%
MI 1.0%

Q3.What are the risks in the 90 days after discharge following TKR (JBJS 2006)?

Study of 222,684 patients
Mortality 0.53%
Infection 0.71%
PE 0.41%

Q4.What risks do you discuss when consenting for TKR?

Anaesthetic risk
Intra-op: bleeding, nerve/vascular injury, fracture
Post-op: infection (wound, deep, urine), DVT/PE, pneumonia, aseptic loosening

Q5.Would you consider bilateral TKR in the same OT and why?

Yes if the patient is fit
Overall less complications
Post-op may need ICU/HDU care
More difficult to rehab
Not everyone progresses to a 2nd TKR

▸ Slide 169 · Status post oxford mobile bearing UKAKnee · 13 questions 1 check expand

Question list

Q1-Q1313 questions — tap to reveal all answerslist

What are the X-ray findings in this failed Oxford mobile bearing UKA?
How do you recognise the PE marker on X-ray?
What history do you take in a failed UKA?
What do you examine in a failed UKA?
What investigations are needed for a failed UKA?
How would you revise a failed UKA?
What are the anticipated difficulties and solutions when revising a UKA?
What are the risk factors for bearing dislocation after mobile bearing UKA?
What is the dislocation rate of the Oxford mobile bearing UKA?
What is the soft tissue tension principle for bearing stability in UKA?
What causes impingement of the mobile bearing?
What happens to the MCL in UKA?
Why is ACL deficiency a contraindication for UKA?

Answers · Q & A

Q1.What are the X-ray findings in this failed Oxford mobile bearing UKA?

Loosening of the tibial baseplate with subsidence into varus
Bearing still on top of the tibial baseplate
No obvious femoral component loosening
No lucency or periosteal reaction suggestive of infection

Q2.How do you recognise the PE marker on X-ray?

Normal PE marker: line in front, point at back

Q3.What history do you take in a failed UKA?

Current symptoms: onset of pain, rest pain, fever or constitutional symptoms
Functional limitations: OKS
Details of the previous operation: pre-op indications, intra-op problems and implant sizing, post-op compliance and delayed wound healing
Other risk factors: obesity, inflammatory joint disease; premorbid state and PMHx

Q4.What do you examine in a failed UKA?

Local: sinus, varus/valgus laxity, ROM
Systemic: is the patient fit for surgery

Q5.What investigations are needed for a failed UKA?

WCC, CRP +/- knee aspiration
Scannogram to check overall alignment
CT for bone stock

Q6.How would you revise a failed UKA?

Pre-op CT to measure bone defect, prepare bone and wedge
Same incision, raise a full thickness skin flap below the fascial layer; extensile approach (quadriceps snip) if needed
Remove the implant first (tibia usually easier; femur with ossilating saw (oscillating saw) + flexible osteotomy)
Take at least 5 intra-op samples at the bone-implant junction for frozen section

Q7.What are the anticipated difficulties and solutions when revising a UKA?

Soft tissue: valgus-varus balance - standby constraint; gap balancing, build up bone defect with augment/cones
Bone: bone defect - use cone or wedge to restore bone stock; implant fixation by zonal fixation

Q8.What are the risk factors for bearing dislocation after mobile bearing UKA?

Patient: compliance, infection
Implant/surgeon: poor tension (MCL, ACL), poor alignment (varus/valgus, rotational), impingement, implant too small/deep flexion
Too loose spins out; too tight impinges and rotates out

Q9.What is the dislocation rate of the Oxford mobile bearing UKA?

1 in 200 (0.5%) in medial UKA
10% in lateral UKA

Q10.What is the soft tissue tension principle for bearing stability in UKA?

Too loose -> spin out
Too tight -> impinge and rotate out
When there is a discrepancy between 90 degree flexion and deep flexion, use a larger femur implant with a thinner insert

Q11.What causes impingement of the mobile bearing?

Cam impingement - the insert hits the medial side of the tibial implant
Cement, meniscus or osteophytes
Undersized femur implant due to retained cartilage / osteophytes over the posterior condyle

Q12.What happens to the MCL in UKA?

Acute MCL and chronic MCL (overstuff) problems
The MCL elongates and loosens; the lateral compartment is under stress and develops OA

Q13.Why is ACL deficiency a contraindication for UKA?

ACL deficiency causes posteromedial OA from anterior subluxation of the tibia
In an ACL intact knee the posteromedial cartilage retensions the MCL
In posteromedial OA the MCL cannot regain tension and becomes contracted

Fact check

Bearing dislocation is 1 in 200 (0.5%) in medial UKA and 10% in lateral UKA — lateral figure outdated/context-specific — 10% applies to the original flat lateral Oxford bearing; the modern domed lateral design has a lower rate of about 1-6% (systematic review 3.7%) — medium confidence — source

▸ Slide 170 · SA vs GA in TKRKnee · 3 questions expand

Question list

Q1-Q33 questions — tap to reveal all answerslist

What are the short-term (30-day) outcomes of spinal versus general anaesthesia in TKR?
Which anaesthetic technique is preferred for total knee replacement?
In which patient group is the benefit of spinal anaesthesia greatest?

Answers · Q & A

Q1.What are the short-term (30-day) outcomes of spinal versus general anaesthesia in TKR?

JBJS 2012 evidence
Less superficial infection
Less transfusion
Shorter OT time
Shorter length of stay
Especially in those with comorbidities

Q2.Which anaesthetic technique is preferred for total knee replacement?

Spinal anaesthesia - less superficial infection, less transfusion, shorter OT time and shorter length of stay at short term (30 days)
Based on JBJS 2012

Q3.In which patient group is the benefit of spinal anaesthesia greatest?

Especially in those with comorbidities

▸ Slide 171 · Valgus kneeKnee · 14 questions expand

Question list

Q1-Q1414 questions — tap to reveal all answerslist

What are the X-ray findings in this valgus knee?
What are the causes of a valgus knee?
What history do you take in a valgus knee?
What do you examine in a valgus knee?
What do you say if a patient with a valgus knee fails conservative management?
What is the aim of TKR in a valgus knee?
What are the approach options and pitfalls in valgus knee TKR?
What bone problems are encountered in valgus knee TKR?
How is coronal imbalance managed in valgus knee TKR?
How is sagittal balance managed in valgus knee TKR?
How is patella tracking managed in valgus knee TKR?
What are the risk factors for peroneal nerve palsy after TKR?
How do you manage acute peroneal nerve palsy after TKR?
How do you manage late peroneal nerve palsy after TKR?

Answers · Q & A

Q1.What are the X-ray findings in this valgus knee?

Bilateral valgus knee, no obvious fracture
Bone quality good, joint space preserved - no evidence of RA
Hypoplastic lateral femoral condyle with increased lateral distal femur angle
Patella lateral subluxation

Q2.What are the causes of a valgus knee?

Rheumatoid arthritis
Post-traumatic
Iatrogenic (HTO)
OA with hypoplastic lateral femoral condyle / constitutional valgus
Haemophilia (Hemophilia), polio, HME

Q3.What history do you take in a valgus knee?

Enquire causes (RA, post-traumatic, iatrogenic HTO, OA with hypoplastic lateral femoral condyle/constitutional valgus, haemophilia, polio, HME)
Disability: KFS

Q4.What do you examine in a valgus knee?

Assess patella tracking
Document peroneal nerve status
ROM, any FFC
Collateral laxity

Q5.What do you say if a patient with a valgus knee fails conservative management?

"This is a complex primary knee and I would refer to an arthroplasty surgeon"

Q6.What is the aim of TKR in a valgus knee?

Stable painless mobile knee
Restore joint line and mechanical axis
Restore sagittal and coronal gap balance
Choose cemented PS knee, standby constraint implant

Q7.What are the approach options and pitfalls in valgus knee TKR?

Medial parapatellar: familiar and good exposure, but poor PL exposure, disrupt VMO cause patellar tracking problem, devascularises skin/patella if lateral release needed
Lateral parapatellar: for a large lateral bone defect needing lateral exposure for augment/cone
Need a coronal Z plasty
Prepare distal femur augment for the hypoplastic lateral condyle

Q8.What bone problems are encountered in valgus knee TKR?

Hypoplastic lateral femoral condyle / peripheral uncontained defect - use TEA + Whiteside as reference, prepare distal femur augment
Lateral tibial plateau defect - usually central contained: minimal bone cut, reference off the medial side 5mm

Q9.How is coronal imbalance managed in valgus knee TKR?

Contracted lateral soft tissue with attenuation of medial soft tissue
LFE sliding osteotomy or MCL advancement
Semiconstraint implant standby

Q10.How is sagittal balance managed in valgus knee TKR?

Release osteophyte, PL capsule first
Then depends on tightness: F: popliteus; E: ITB
Both: piecrust LCL

Q11.How is patella tracking managed in valgus knee TKR?

Lateral retinacular release (1cm from the border)
Medial imbrication
ER femoral and tibial implants

Q12.What are the risk factors for peroneal nerve palsy after TKR?

Fixed flexion contracture + valgus
Valgus deformity >12 degrees
Epidural anaesthesia for pain control
Previous laminectomy
Overall 2% esp pre op valgus >12deg; suggest intra-op avoid excessive release; post op recovery room asssessment; prophylactic exploration is not beneficial

Q13.How do you manage acute peroneal nerve palsy after TKR?

Remove the compressive dressing
Check for haematoma, check the drain
Flex the knee
Check anaesthetic notes for blocks used
Check XR: lateral overhang, cement, sawblade cut at fibula

Q14.How do you manage late peroneal nerve palsy after TKR?

AFO to prevent foot drop
Regular follow-up, NCT to document recovery
+/- exploration if no improvement (controversial)

▸ Slide 172 · Tell me the pros and cons of one versus two stageKnee · 7 questions expand

Question list

Q1-Q77 questions — tap to reveal all answerslist

What is the main concern in deciding one versus two stage revision?
What are the advantages of one stage revision for a failed HTO?
What are the anticipated difficulties with approach and exposure in one stage revision?
What are the key steps of reconstruction in one stage revision?
How do you choose between osteotomy and TKR?
What are the advantages of UKA over HTO?
What are the survival figures for UKA and HTO?

Answers · Q & A

Q1.What is the main concern in deciding one versus two stage revision?

Whether 1. bone stock 2. soft tissue difficulties can be dealt with in one go

Q2.What are the advantages of one stage revision for a failed HTO?

One GA session
Shorter rehab
Only one extra-articular deformity; CORA is close to the joint
Long stem bypasses the screw hole - less stress riser
Decreased infection and wound problems

Q3.What are the anticipated difficulties with approach and exposure in one stage revision?

Use previous/most lateral incision, maintain a thick fasciocutaneous flap
Medial parapatellar approach (give reason and cons)
Removal of implant - prepare screwdrivers/broken screw set, protect the MCL
Inspect osteotomy healing/infection, take samples for c/st
Retropatellar scar: prepare rectus snip, quadricepsplasty, TT osteotomy

Q4.What are the key steps of reconstruction in one stage revision?

Femur: TEA + Whiteside line, expect lateral condyle erosion, less VCA
Tibia: extramedullary guide, reference off lateral 2mm or medial 5mm, Beware of large tibial slope from index operation
Obtain balance of the extension gap; PS implant, standby constraint; 2/3 zones of fixation; cemented fixation for poor bone
Tibia stem bypasses screw hole by 2 cortical widths, prepare offset stem
Patellar tracking: lateral release, medialised button; ensure no femoral/tibial ER; monitor peroneal nerve

Q5.How do you choose between osteotomy and TKR?

TKR ideal: old, less active, tricompartmental, more soft tissue imbalance, larger deformity
Osteotomy ideal: young fit non-smoker, good bone stock/range/skin, isolated compartment disease, deformity not severe

Q6.What are the advantages of UKA over HTO?

Faster recovery, no reliance on bone healing, early weight bearing
Smaller incision, less pain, shorter length of stay
Easier conversion; less blood loss and morbidity
HTO: preserves bone stock, wider indication (ACL deficiency), Better kinematics, ?ROM better; Cao 2018 - HTO for higher activity

Q7.What are the survival figures for UKA and HTO?

UKA: 21.4% revision rate at 15 years (Australian joint registry)
HTO: Kunze AJSM 2020 86% at 6 years; Insall series 70% at 10 years

▸ Slide 173 · Standing XR right knee showing osteoarthritis change mainly over medial compartmKnee · 15 questions expand

Question list

Q1-Q1515 questions — tap to reveal all answerslist

What does the standing X-ray of the right knee show?
How would you assess a patient with medial compartment OA of the knee?
What is the management algorithm for isolated medial OA of the knee?
What are the indications for HTO?
What are the indications for UKA and TKA in isolated medial OA?
What are the pros and cons of UKA versus HTO?
What are the options for HTO?
What are the contraindications and advantages of medial open wedge HTO?
What are the disadvantages of medial open wedge HTO?
What is the Nakamura classification of lateral cortex fracture in open wedge HTO?
What are the pros and cons of lateral closing wedge HTO?
What did the JBJS 2014 RCT show about open versus closing wedge HTO?
How do you differentiate the HTO types on X-ray?
What are the outcomes of HTO?
How does UKA compare with TKR?

Answers · Q & A

Q1.What does the standing X-ray of the right knee show?

Osteoarthritis mainly over the medial compartment
Lateral compartment preserved
Slightly varus alignment

Q2.How would you assess a patient with medial compartment OA of the knee?

Hx: age, functional demand, occupation, symptom onset/progression, previous treatment, Inflammatory arthritis, infection, trauma
P/E: BMI, FFC, deformity, range, ACL, instability, NV, varus thrust, skin
X-ray: scannogram, lateral, skyline

Q3.What is the management algorithm for isolated medial OA of the knee?

Conservative management according to AAOS guideline
Consider HTO, UKR, TKR
Needs an individualized approach: age, functional demands, bone and soft tissue integrity, ACL status

Q4.What are the indications for HTO?

Patient: <60 years old, active
Joint: unicompartmental OA, FFC < 5 degree, ROM > 90, correctable varus <5 degrees, no instability
Aim: unload medial compartment, shift mechanical axis, overcorrection 3-6deg

Q5.What are the indications for UKA and TKA in isolated medial OA?

UKA: Kozin and Scott criteria, aim to undercorrect
TKA: absolute indication if ACL insufficient, deformity too large, or poor range
TKA may consider CR for theoretical advantages

Q6.What are the pros and cons of UKA versus HTO?

HTO pros: preserve bone stock, wider indication (ACL deficiency), Better kinematics and ROM
HTO cons: union problems, cosmesis (valgus knee), longer rehab
Cao 2018 meta-analysis: UKA less revision/complications/post-op pain, HTO better ROM; HTO may be better for high activity level

Q7.What are the options for HTO?

Medial open wedge
Lateral closing wedge
Dome osteotomy

Q8.What are the contraindications and advantages of medial open wedge HTO?

C/I if patella baja as it will elevate the joint line
Advantages: higher corrective power, no fibular osteotomy with decreased peroneal nerve injury, less tibial offset, less scarring leading to less patella baja

Q9.What are the disadvantages of medial open wedge HTO?

Non-union leading to implant failure (plate and screw)
Lateral cortex fracture
Increase posterior slope
Bone graft donor site morbidity (may use calcium phosphate wedge graft)

Q10.What is the Nakamura classification of lateral cortex fracture in open wedge HTO?

Type1, along osteotomy
Type2, go down
Type3, go intraarticular region

Q11.What are the pros and cons of lateral closing wedge HTO?

Advantage: fewer non-unions
Disadvantages: peroneal nerve palsy, short limb, Distort anatomy, truncated making TKR harder, scarring leading to patella baja

Q12.What did the JBJS 2014 RCT show about open versus closing wedge HTO?

No clinical or radiological difference between open and closing wedge

Q13.How do you differentiate the HTO types on X-ray?

Fibular osteotomy = closing wedge or dome (closing wedge shows a step on the lateral side)
Open wedge usually has a plate; dome may have 2 staples

Q14.What are the outcomes of HTO?

65% at 10 years (Insall); most HTOs eventually require TKR
Best results: younger, moderate varus; obesity, undercorrection and excessive overcorrection are adverse
Ideal correction: hip-knee-ankle angle between 2° & 6° (overcorrection); plan with Miniaci method, Fujisawa point; the overall preoperative state of the knee is the most important determinant

Q15.How does UKA compare with TKR?

UKA preserves both cruciates: better knee function, better joint forgettability, quicker rehab, less blood loss and morbidity
Good survival data come from high volume centres; overall survival 90% at 10 years (Swedish joint registry)
Long term survival still inferior to TKR: 3.2x higher revision rate in the UK joint registry (possible selection bias)
BMJ 2019 Andrew Price meta-analysis: both viable for isolated unicompartmental OA; UKA better in several outcome domains but TKA has lower revision risk

▸ Slide 174 · The indication by ScottKnee · 3 questions expand

Question list

Q1-Q33 questions — tap to reveal all answerslist

What are Scott's indications for UKA?
What are the contraindications to UKA?
What are the complications and failure mechanisms of UKA?

Answers · Q & A

Q1.What are Scott's indications for UKA?

Intact ACL
Flexion arc >90
Contracture <5
Varus deformity <10, passively correctable to neutral
Generally age >60, weight <82kg, not a manual worker

Q2.What are the contraindications to UKA?

Multicompartmental involvement
Inflammatory arthritis
Significant fixed deformity (FFC >10 degrees)
Previous meniscectomy on the other side
ACL deficiency (in mobile bearing UKA)

Q3.What are the complications and failure mechanisms of UKA?

Stress fracture (always tibial) with heavy weight/activity
Fixed-bearing implants: fail with mechanical loosening
Mobile-bearing implants: fail from disease progression
Patella impingement may need revision to TKR

▸ Slide 175 · Lateral dislocation of patellar in a case after TKRKnee · 4 questions expand

Question list

Q1-Q44 questions — tap to reveal all answerslist

What factors affect patellar dislocation after TKR?
How do you assess patellar tracking intra-operatively?
How do you investigate post-operative patellar dislocation?
What are the treatment options for post-TKR patellar dislocation?

Answers · Q & A

Q1.What factors affect patellar dislocation after TKR?

Pre op: valgus knee with lateral tightness
Implant alignment/position increasing the Q angle
Patella component: laterally placed, overstuff
Femoral component: medially placed, IR, overstuff
Tibial component: medially placed, IR; overall excessive valgus

Q2.How do you assess patellar tracking intra-operatively?

No thumb technique
If failed, release the tourniquet and try again
If still failed, release the lateral retinaculum 1cm from the patella

Q3.How do you investigate post-operative patellar dislocation?

Rule out infection, loosening, fracture
Check alignment with CT (axial cuts)
Check rotation: TEA vs posterior femoral component edge, perpendicular line of posterior tibial plane through stem centre, TT to stem line for IR

Q4.What are the treatment options for post-TKR patellar dislocation?

Correct the underlying causes
If no alignment problem: Insall procedure (lateralize and distalise VM)
Lateral retinaculum release, vastus medialis advancement, medial plication
Bony: TT osteotomy

▸ Slide 176 · Post TKR knee painKnee · 6 questions expand

Question list

Q1-Q66 questions — tap to reveal all answerslist

What is your history in a patient with post-TKR knee pain?
What do you examine in a patient with post-TKR knee pain?
What investigations are needed for post-TKR knee pain?
What are the intrinsic causes of post-TKR knee pain?
What causes posterolateral knee pain after TKR?
What causes posteromedial pain and what are the extrinsic causes of post-TKR pain?

Answers · Q & A

Q1.What is your history in a patient with post-TKR knee pain?

Rule out infection: risk factors, delayed wound healing, constitutional symptoms
Nature of pain: referred, triphasic, resting
Current functional limitations

Q2.What do you examine in a patient with post-TKR knee pain?

Local: soft tissue, sinus, ROM, FFC, instability
Systemic: hygiene

Q3.What investigations are needed for post-TKR knee pain?

X-ray: early loosening, sizing, overhang, PFJ overstuffing, HO
Scannogram for mechanical alignment
Bloods: ESR, CRP
Aspiration: C/ST + WBC + alpha defensin (MSIS score)
CT for malrotation

Q4.What are the intrinsic causes of post-TKR knee pain?

Infection, loosening, malalignment, instability
Loose bodies (cement, osteophyte)
PFJ problem, impingement

Q5.What causes posterolateral knee pain after TKR?

Tibial tray overhang
Retained PL osteophyte/cementophyte - biceps tendonitis, popliteus impingement
ITB dysfunction - lateral pain with ROM 20-80 degrees

Q6.What causes posteromedial pain and what are the extrinsic causes of post-TKR pain?

Semimembranosus tendonitis
Dual pathology (hip, foot, PVD)
CRPS, cutaneous neuromas

▸ Slide 177 · Post TKR instabilityKnee · 12 questions expand

Question list

Q1-Q1212 questions — tap to reveal all answerslist

What are the 4 Ps to mention when assessing instability after TKR?
What history is important in post-TKR instability?
What are the components of the Knee Society knee score?
What are the components of the Knee Society function score?
What local examination findings do you look for in post-TKR instability?
What systemic examination and gait findings are relevant in post-TKR instability?
How do you work up and manage post-TKR instability?
What are the types of instability after TKR?
What causes flexion (AP) instability after TKR and how is it treated?
How do you differentiate symmetrical from asymmetrical extension (ML) instability?
What is mid-flexion instability and what are its potential causes?
How are genu recurvatum and global instability after TKR managed?

Answers · Q & A

Q1.What are the 4 Ps to mention when assessing instability after TKR?

Patient
Prosthesis
Procedure
Present status

Q2.What history is important in post-TKR instability?

Initial indication and diagnosis
PMHx: connective tissue disease, inflammatory joint disease, Charcot arthropathy
Preop ROM and pre-existing laxity
Intraoperative complications
Postop compliance and recent trauma
Current function

Q3.What are the components of the Knee Society knee score?

Pain
FFC (fixed flexion contracture)
Extensor lag
Total ROM
Alignment
Stability (AP and ML)

Q4.What are the components of the Knee Society function score?

Walking aids
Stairs
Walking tolerance

Q5.What local examination findings do you look for in post-TKR instability?

Soft tissue envelope, ROM, any recurvatum
Quads power
Collateral ligament testing, A and P drawer
Patellar tracking

Q6.What systemic examination and gait findings are relevant in post-TKR instability?

generalized ligamentous laxity (generalised)
Check proprioception
Gait: varus or valgus thrusting gait
CT for implant position

Q7.How do you work up and manage post-TKR instability?

Determine the cause
Bone: X-ray and CT
Soft tissue: examination
Rule out infection: bloods +/- aspiration

Q8.What are the types of instability after TKR?

Flexion (AP)
Extension (ML)
Mid-flexion
Genu recurvatum
Global

Q9.What causes flexion (AP) instability after TKR and how is it treated?

Knee dislocation (PS knees can jump the post)
Undersized femoral component --> upsize
Overresection of posterior condyle --> upsize or posterior femoral augments
Too much tibial slope --> reduce slope + use PS prosthesis
PCL insufficiency in a CR --> revision to PS knee

Q10.How do you differentiate symmetrical from asymmetrical extension (ML) instability?

Symmetrical = bony problem (too much distal femur cut or oversized femoral implant)
Asymmetrical = ligament problem

Q11.What is mid-flexion instability and what are its potential causes?

Malrotation when the knee is flexed between 45-90 degrees
Poorly understood
Femoral component design in the sagittal plane
Attenuation of anterior MCL
Overall geometry of the tibiofemoral joint

Q12.How are genu recurvatum and global instability after TKR managed?

Recurvatum: fixed valgus deformity and IT band contracture; causes polio, RA, Charcot
Recurvatum: long-stemmed PS or ML constrained implant; rotating hinge for salvage as residual hyperextension may occur
Global: due to severe bone loss
Global: varus-valgus constrained prosthesis at minimum, hinged prosthesis +/- augments, megaprosthesis if severe bone loss

▸ Slide 178 · Post TKR stiffnessKnee · 5 questions expand

Question list

Q1-Q55 questions — tap to reveal all answerslist

What preoperative factors predispose to stiffness after TKR?
What intraoperative causes produce poor flexion after TKR?
What intraoperative causes produce poor extension after TKR?
What intraoperative causes produce poor global ROM after TKR?
What postoperative complications cause stiffness after TKR?

Answers · Q & A

Q1.What preoperative factors predispose to stiffness after TKR?

Poor preoperative range of movement
RA
Post traumatic (post-traumatic) knee
Obesity

Q2.What intraoperative causes produce poor flexion after TKR?

Tight flexion gap: inadequate tibial slope, oversized femur, posteriorized femur
Overstuffed PFJ
Raised joint line (patella baja)

Q3.What intraoperative causes produce poor extension after TKR?

Flexed PS component
Posterior osteophytes
Inadequate distal femur cut

Q4.What intraoperative causes produce poor global ROM after TKR?

Big polyethylene insert
Inadequate tibial cut

Q5.What postoperative complications cause stiffness after TKR?

Arthrofibrosis
Infection
CRPS
HO

▸ Slide 179 · Patellar clunk syndromeKnee · 5 questions expand

Question list

Q1-Q55 questions — tap to reveal all answerslist

What is patellar clunk syndrome?
How does patellar clunk differ from patellar crunch and dislocation?
What preoperative risk factors predispose to patellar clunk?
Which patellar implant factors cause patellar clunk?
Which femoral and insert factors cause patellar clunk?

Answers · Q & A

Q1.What is patellar clunk syndrome?

Painful, palpable clunk at the PFJ of a PS TKR
Fibrous nodular scar at the posterior surface of the distal quads tendon / superior patellar pole
Catches on the box of the femoral component during knee extension
Flexion, then catch during extension

Q2.How does patellar clunk differ from patellar crunch and dislocation?

Crunch: scar around the patellar implant, crunch sensation moving from extension to flexion, catch during flexion
Clunk: catch near extension
Dislocation: clunk near flexion

Q3.What preoperative risk factors predispose to patellar clunk?

Patella baja
Previous knee surgery
Valgus knee
Extensive synovitis

Q4.Which patellar implant factors cause patellar clunk?

Small patellar implant --> decreased quads tendon contact forces against the superior intercondylar box --> fibrosynovial proliferation
Overresection / thin implant --> reduces the offset of the quad tendon
Inferior placement --> bare bone at superior pole exposed

Q5.Which femoral and insert factors cause patellar clunk?

PS femur (IB2 with short, abrupt flange)
Increased posterior femoral condylar offset
Small femoral component
Femoral component in flexion
Thick PE insert causing raised joint line and patella baja

▸ Slide 180 · Indications for knee arthrodesisKnee · 6 questions expand

Question list

Q1-Q66 questions — tap to reveal all answerslist

What are the indications for knee arthrodesis?
What are the contraindications to knee fusion?
What alignment should a knee arthrodesis be fixed in?
Compare plate, nail and external fixator for knee arthrodesis.
What are the complications of knee arthrodesis?
What are the key considerations when converting a fused knee to TKA?

Answers · Q & A

Q1.What are the indications for knee arthrodesis?

Loss of extensor mechanism
Charcot arthropathy
Tumour resection
Unsalvageable TKR

Q2.What are the contraindications to knee fusion?

Absolute: active infection
Relative: bilateral knees involved
Relative: ipsilateral hip fusion
Relative: contralateral amputation
Relative: significant bone loss

Q3.What alignment should a knee arthrodesis be fixed in?

7 degrees valgus
15 degrees flexion
0-10 degrees external rotation (match the other leg)
On examination, tell pathological from surgical fusion by looking at alignment

Q4.Compare plate, nail and external fixator for knee arthrodesis.

Plate: advantage allows compression; disadvantage extensive dissection
Nail: advantage load transmitting (increases healing and early WB); disadvantage difficult insertion
Ex Fix: advantage usable in poor soft tissue envelope; disadvantage pin tract infection

Q5.What are the complications of knee arthrodesis?

Nonunion
Infection
Adjacent joint disease
Supracondylar and proximal tibia fracture

Q6.What are the key considerations when converting a fused knee to TKA?

Preop: extensor mechanism (clinical/EMG/MRI), contracted soft tissue envelope (expander), CT for bone stock, instruments (navigation, BG/augment, semiconstraint + stem)
Skin: choose most lateral wound, mainly full thickness fasciocutaneous flap
Bone stock: osteoporotic, hard to evaluate with hardware; +/- staged implant removal + bone graft; prepare BG/augment/stem
Soft tissue: shortened extensor mechanism --> quadriceps VY plasty; deficient collaterals --> semiconstraint; rotational flap for closure
Previous deformity

▸ Slide 181 · hemophiliaKnee · 10 questions expand

Question list

Q1-Q1010 questions — tap to reveal all answerslist

Describe the X-ray features of haemophilic arthropathy.
What is the Arnold-Hilgartner classification?
Tell me about haemophilia.
What is the pathology of haemophilic arthropathy?
What history and examination findings are important in haemophilia?
What investigations are needed in haemophilia?
What is the aim and conservative management of haemophilic joint disease?
How are bleeding episodes and surgery managed in haemophilia?
What are the difficulties of TKR in haemophilia?
What is the prognosis of TKR in haemophilia?

Answers · Q & A

Q1.Describe the X-ray features of haemophilic arthropathy.

Decreased joint space, OA change, osteopenia
Ballooning of distal femur (paediatric epiphyseal overgrowth), wide notch, squaring of femoral condyle
Squaring of patella (Jordan sign), no fracture
Large subchondral cyst
Pseudotumour
Ddx: OA, post-traumatic OA, post-infectious OA, inflammatory arthritis

Q2.What is the Arnold-Hilgartner classification?

0 normal
I soft tissue synovitis, bone normal
II epiphyseal hypertrophy, osteopenia
III patellar squaring, subchondral cyst, widened notch
IV joint space narrowing
V ankylosis

Q3.Tell me about haemophilia.

Inherited disease of clotting dysfunction; most common type A (factor 8) and type B (factor 9), both X-linked recessive
Childhood onset of easy bleeding, usually at joints and intramuscular regions; mucosa less likely; affects hinged joints (knee, elbow, ankle)
Mild 5-25% / moderate 1-5% / severe <1% factor concentration determines bleeding risk
Recombinant factor transfusion in bleeding episodes (no blood-borne disease now)
Factor VIII inhibitors (including IgG antibodies) in 5-25% - inhibit response to therapeutic factor (monoclonal recombinant factor VIII); relative contraindication to surgery, screen preoperatively
Factor <1% --> spontaneous bleeding

Q4.What is the pathology of haemophilic arthropathy?

Bleeding --> haemosiderin deposition --> synovitis --> bleeding
Repeated haemarthrosis --> capsular fibrosis
Articular damage (lyzosomal enzyme from synoviocytes) (lysosomal enzymes from synoviocytes)
Hyperemia --> LLD/ deformity (+/- overgrowth) (hyperaemia --> LLD/deformity)
Disuse: atrophy, contracture, osteopenia --> arthropathy

Q5.What history and examination findings are important in haemophilia?

Hx: symptoms of bleeding/effusion, male or female, onset, previous medical follow-up, investigation, factor transfusion, complications of treatment
PE: joint effusion, ROM, deformity, gait (function)
Numbness in the L4 distribution caused by iliacus haematoma compressing the femoral nerve

Q6.What investigations are needed in haemophilia?

Blood test: Hb, aPTT prolonged, PT normal
Bethesda assay measures factor 8/9 antibody (megadose/ neutralize)
Preop workup: factor transfusion, cell saver, check inhibitor IgG, HIV testing

Q7.What is the aim and conservative management of haemophilic joint disease?

Systemic: refer haematologist for bleeding control (regular/symptomatic transfusion)
Aim: preventive - decrease bleeding episodes, prevent soft tissue contracture, deformity and ankylosis
Conservative: analgesics + physiotherapy
Prophylactic factor replacement >2%

Q8.How are bleeding episodes and surgery managed in haemophilia?

Acute haemarthrosis: aspiration, factor infusion aim 40-50%, splint/compressive dressing, +/- steroid, early rehab
Recurrent: aspiration, factor VIII >20% for 6 weeks, IA steroid, cast; desmopressin
Chronic stage 1-3 (joint space preserved): synovectomy, radioactive synoviorthesis with colloidal 32P chromic phosphate
Chronic stage 4-5: arthrodesis / TKR (higher infection rate)
Skeletal surgery: factor to 100% in 1st week, keep >50% in 2nd week
Targets: vigorous physiotherapy 20%; acute haematoma 30%; acute haemarthrosis / soft tissue surgery 40-50%

Q9.What are the difficulties of TKR in haemophilia?

Pre-op: factor transfusion, cell saver, check inhibitor IgG, HIV testing
Intra-op soft tissue: contracture, easy bleeding
Intra-op bone: soft bone easy fracture, bone graft cysts, large femoral epiphysis (difficult sizing), small IM canal, valgus knee, tibia posterolateral subluxation + decreased slope, thin patella
Post-op: factor transfusion to cover (1 week 100%, 2 weeks >75%), haematoma formation

Q10.What is the prognosis of TKR in haemophilia?

J Arthroplasty meta-analysis 2022 Fenelon: overall complication rate 28.7%
Similar survivorship to the general population

▸ Slide 182 · TKR in polio patientsKnee · 5 questions expand

Question list

Q1-Q55 questions — tap to reveal all answerslist

What is the pathogenesis of knee deformity in polio?
What bone problems complicate TKR in polio patients?
What soft tissue problems complicate TKR in polio patients?
How is recurvatum addressed during TKR in polio?
What is the reported outcome of TKR in polio patients?

Answers · Q & A

Q1.What is the pathogenesis of knee deformity in polio?

Weak quads with failed knee extension in stance phase
Hyperextension of the knee to bring the ITB anterior to the knee centre of rotation, acting as an extensor
Gradual stretching of the posterior capsule
Weight bearing and gravity elongate the tibial condyles posteriorly
Articular surface angle to the tibial axis becomes more acute; proximal third of tibia bows posteriorly

Q2.What bone problems complicate TKR in polio patients?

Genu recurvatum and genu valgum
Osseous abnormalities: narrow canal, metaphyseal and articular deformities
Osteoporosis
ER of tibia with subluxed patella, patella baja
Bone loss

Q3.What soft tissue problems complicate TKR in polio patients?

Lax medial and posterior structures
Tight lateral structures
Weak quads
Fixed flexion contracture

Q4.How is recurvatum addressed during TKR in polio?

Exposure limited by patella baja: lateral retinacular release, medial soft tissue release, quads snip / TTO
Extension gap: cut less distal femur
Flexion gap: small component to increase flexion gap
Constraint

Q5.What is the reported outcome of TKR in polio patients?

7% revision rate at 6 years (systematic review, EFORT 2018)

▸ Slide 183 · Bilateral knee XRKnee · 7 questions expand

Question list

Q1-Q77 questions — tap to reveal all answerslist

What is a Charcot joint and what are the X-ray findings in the knee?
What are the differential diagnoses for a destroyed knee?
What history and examination findings are relevant in a Charcot knee?
How do you rule out infection in a Charcot knee?
What underlying causes of a Charcot joint should be sought?
What is the management of a Charcot knee?
What are the issues with TKR in a Charcot knee and the reported outcomes?

Answers · Q & A

Q1.What is a Charcot joint and what are the X-ray findings in the knee?

Progressive, noninfectious, destructive disorder of bone and joint with underlying sensory neuropathy
Destruction of the joint with subluxation
Periarticular bone debris
Increased bone density

Q2.What are the differential diagnoses for a destroyed knee?

Infection
Advanced OA knee
RA

Q3.What history and examination findings are relevant in a Charcot knee?

Hx: premorbid function, pain, instability, functional limitations, expectations
PE: sensation and proprioception
Difficult to differentiate from osteomyelitis

Q4.How do you rule out infection in a Charcot knee?

Difficult to differentiate from osteomyelitis
Blood tests, WBC scan, aspiration, synovial biopsy
Bone scan both hot; WBC scan may be cold in Charcot

Q5.What underlying causes of a Charcot joint should be sought?

DM
Syphilis (Argyle-Robertson pupil)
Hansen disease
Syringomyelia

Q6.What is the management of a Charcot knee?

Limitation of activity and bracing
Surgery: key is to intervene at the consolidation phase
Fusion is classical: resect sclerotic bone (dead bone), apposition of bleeding bone; prolonged immobilisation >12 weeks
Recent trend towards TKR

Q7.What are the issues with TKR in a Charcot knee and the reported outcomes?

Poor bone stock; soft tissue laxity --> instability; poor implant fixation --> 2/3 zonal fixation
TKR reported to give good pain relief; some say relatively contraindicated (high complication rate)
EFORT meta-analysis 2021: survivorship 85.4% (mid >5years to long term >10years)
Complication rate 26.4%: instability 24.0%, periprosthetic fracture 17.4%, infection 13.0%, ligament injury 10.9%, aseptic loosening 10.9%

▸ Slide 184 · Key numbers:Knee · 3 questions expand

Question list

Q1-Q33 questions — tap to reveal all answerslist

What coronal and sagittal deformity thresholds are quoted for osteotomy vs TKA?
What are the prerequisites, advantages and disadvantages of TKA with intraarticular correction?
What are the advantages and disadvantages of extraarticular correction then TKR?

Answers · Q & A

Q1.What coronal and sagittal deformity thresholds are quoted for osteotomy vs TKA?

Coronal: femur >20, tibia >30
or >20 in the sagittal plane
Then consider severity --> soft tissue --> LLD --> nail/plate

Q2.What are the prerequisites, advantages and disadvantages of TKA with intraarticular correction?

Prerequisite: not to violate the collateral ligament (+ minimal malrotation)
Advantages: less extensive, easy and fast rehab, avoid osteotomy
Disadvantages: soft tissue imbalance, malrotation of the ankle joint

Q3.What are the advantages and disadvantages of extraarticular correction then TKR?

Greater surgical flexibility (open vs closing wedge osteotomy, technically easier)
Allows healing of the osteotomy (no risk of cement extrusion from TKR)
Improve knee alignment – might alleviate symptoms and delay TKA
Disadvantages: 2 surgeries, 2 anaesthetics, longer rehab

▸ Slide 185 · Revision TKRKnee · 7 questions expand

Question list

Q1-Q77 questions — tap to reveal all answerslist

What history and examination findings are important before revision TKR?
What investigations are required before revision TKR?
What are the aims of revision TKR and when is a constraint implant indicated?
What must be prepared preoperatively for revision TKR?
Describe the intraoperative approach and implant removal in revision TKR.
What is the bone reconstruction ladder and AORI classification in revision TKR?
What are the postoperative instructions after revision TKR?

Answers · Q & A

Q1.What history and examination findings are important before revision TKR?

Hx: preop, intraop (trace OT record) and postop course
Recent infection (skin, dental, UTI); nature of pain
Local PE: soft tissue envelope, ligamentous laxity, ROM, pulses
Systemic PE: signs of active infection e.g. ulcer, dirty toes

Q2.What investigations are required before revision TKR?

Bloods - inflammatory markers
Joint aspirate
XR + scannogram
CT

Q3.What are the aims of revision TKR and when is a constraint implant indicated?

General: stable, painless, mobile knee
Specific: restore joint line and mechanical axis, balance coronal and sagittal gaps
Constraint because of loss of collateral function
Indications: flexion instability with largest femoral component + thickest insert
Extension instability (recurvatum)
ML instability upon full knee extension

Q4.What must be prepared preoperatively for revision TKR?

Counsel patient re survival and complication rate; know previous implant, contact sales on standby
Implant removal devices: oscillating saw, flexible osteotome, burr, Gigli saw
Inform pathology lab for intraop frozen section; prepare cement spacer in case of infection
Bone loss: prepare augment, wedge, cone, long stem
Varus-valgus constrain, rotating hinge prosthesis

Q5.Describe the intraoperative approach and implant removal in revision TKR.

Previous approach, most lateral incision (6 cm skin bridge; blood supply to skin from medial side); full thickness flap
Evert patella, partial lateral release to lateral gutter; careful not to disrupt extensor mechanism
Prepare extensile approach: quadricepsplasty, TT osteotomy, rectus snip
Remove femur first, then tibia using stacked osteotome or K wire technique
Remove all cement, take representative sample x5 for c/st, also frozen section (x5 samples for C/S); assess bone loss (AORI)

Q6.What is the bone reconstruction ladder and AORI classification in revision TKR?

Ladder: cement +/- screw, bone graft (structural or morselized), modular augmentation (wedges/blocks), custom made/tumour/hinge prosthesis
Identify joint line (meniscal scar, fibular head, epicondyles, tibial tuberosity); do tibia first to restore gaps; aim 2/3 zones fixation (long cementless stem = short cemented stem, Jones BJJ 2012)
AORI 1: contained minor defects, intact metaphyseal bone, implant stable
AORI 2: uncontained defect, damaged metaphyseal bone requiring reconstruction for stability
AORI 3: deficient metaphyseal segment compromising major portion of femoral condyle/tibial plateau, +/- collateral or patellar tendon detachment

Q7.What are the postoperative instructions after revision TKR?

Tell the patient to maximise rehab to avoid stiffness
Rehab: weight bear as tolerated
Insert drain
Antibiotics til c/st is back

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