TKR complications Flashcards
1
Q
What is the risk factors for TKR complications?
A
- Obesity
- prior surgery
- diabetes
- inflammatory arthritis
2
Q
Describe the types of instability?
A
- axial instability ( mediolateral)
- Flexion instability (anterioposterior)
3
Q
How do you treat axial instability?
A
- If flexion and extension are the same
- thicker tibial liner
- If flexion and extension asymmetric
- augmentation & component revision
4
Q
How do you tx flexion instability?
A
- Occurs when flexion gap > than extension gap
- when femoral component is downsized or moved anterior
- posterior dislocation is 0.15% of TKR with posterior stabilisation
- PCL retaining should be revised to posterior- stabilised
- post stabilised revised if recurrent dislocation
5
Q
What is the risk of vascular injury?
A
- Low incidence
- stay medial with retractors
- avoid sharp dissection in post compartment of knee
- popliteal artery is 9mm posterior to posterior cortex when knee is flexed to 90o
- if injury suspected consider dropping tourniquet after bone cuts
6
Q
What is the incidence of nerve palsy?
A
- 0.3%
- increased risk with valgus and/or flexion deformity
- incidence increases to 3-4% with valgus deformity
- increase risk if tourniquet >120 mins, preop neuropathy, abberrent retractor placement
- tx
- release bandages
- flex knee
- AFO
7
Q
What are the risk factors for post op stiffness?
A
- Preop stiffness
- most important factor ( ultimate motion is +/- 10o
- large body habitus
- female
- extreme varus
- young pts
- limited intraop extension
- poor pt compliance
- low pain tolerance
- technical factors
- post op
- infection
- delayed healing
- periprosthetic fx
- complex regional pain syndrome
- HO
8
Q
What is the tx for post op stiffness?
A
-
Manipulation under anaesthesia
-
flexion <90 degrees after first 6 weeks post op
- risk fx/ extensor mechanism rupture
- after 3 months post op manipulation assoc with greater risk and lower benefit
-
flexion <90 degrees after first 6 weeks post op
-
Scar excison, quadricepsplasty, possible revision of components
- persistent late stiffness
- CPm not been shown to improve longterm rom or clinical outcomes
9
Q
What the incidence of extensor mechanism rupture?
A
- Patellar tendon rupture is a rare and devastating complication after TKR
- incidence 0.17-2.5%%
- Quads tendon rupture is extremely rare 1%
- tx by reconstruction with an achilles tendon/bone allograft
10
Q
What is the risk factors for wound complications?
A
- _Systemic _
- DM
- vascular disease
- RA
- Certain medication
- smoking
- poor nutritional status
- albumin <3.5g/L
- Total lymphocyte count <1,500/uL
- Perioperative anaemia
- obesity
-
Local factors
- prevision incision
- skin bridge >5-6cm
- avoid crossing previous skin incisions at angle <60 degrees
- knee deformity
- skin adhesions
- poor local blood supply
- prevision incision
- NB nasal oxgyen should be given for first 1-2 days in all at risk pts
- if drainage occurs longer than 4 days then aggressive surgical mx should be done
11
Q
What is the risk of metal hypersensitivity?
A
- rare
- nickel found in colbalt- chromium alloy is most important offending agent
12
Q
What are the risks for formation of Heterophic ossification?
A
- Less frequent than after THR
- Risk factors
-
periosteal stripping off ant femur
- formation of HO proximal to anterior flange of femoral component
- leads to tethering of extensor mechanism/quads
- HO may -> indolent infection
- following arthrofibrosis
- male gender
- Obesity
- Post traumatic deformity
-
periosteal stripping off ant femur
13
Q
What is patellar clunk syndrome?
A
- rare phenomenon only seen in posterior stabilised TKR
- caused by fibrous nodule that forms on posterior surface of quadriceps tendon above the superior pole of patella
- Pt experience painful pop as knee is extended approx 40o flexion
- tx by arthroscopic vs open resection of fibrous nodule
14
Q
What are the risk factors for TKR periprosthetic fx?
A
-
Femoral notching
- notching of anterior femur shown to weaken femur but has not been proven to equate with higher rates of supracondylar femur fx
- RA
- Steriod therapt tx
- Osteopenia or osteoporosis
- neurological disorders
15
Q
What is the incidence of periprosthetic TKR fx?
A
- 0.3-2.5%
- incidence higher in revision TKR but not estimated stats reported
16
Q
Name a classification system for periprosthetic TKR fx?
A
- Su and Associates
- type 1 - fx is proximal to femoral component
- type 2- fx orginates at proximal aspect of the femoral component and extends proximally
- type 3- any part of the fx line is distal to the upper edge of anterior flange of the femoral component
20
Q
What is the classification for tibial periprosthetic fx?
A
- Felix and associates
- type 1 =fx to tibial plateau
- type 2= fx adjacent to tibial stem
- type 3= fx tibial shaft, distal to component
- type 4= fx of tibial tubercle
