Revision Hip/Knee Arthroplasty (Complete) Flashcards
1
Q
What are general considerations and preparation in revision TKA?
[Instr Course Lect. 2014; 63:239-51]
A
- Rule out infection
* a.History, physical, bloodwork (CBC, ESR, CRP), joint aspiration - Previous OR note
- a.Implants
- b.Approach
- c.Complications
3.Radiographs
- a.AP, lateral and full length standing
- b.Previous radiographs for comparison
- Determine revision implants
* a.Stems, augments, cones/sleeves, unconstrained, varus/valgus constrained, hinged, endoprosthesis - Surgical steps
* See Separate Flashcard
2
Q
What are the surgical Steps for Revision TKA?
A
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
- 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
- Bone defects
- 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
3
Q
What are general considerations and Preparation in revision THA?
A
- Rule out infection
* a.History, physical, bloodwork (CBC, ESR, CRP), joint aspiration - Previous OR note
* a.Implants, Approach and Complications - Radiographs
- a.AP pelvis, AP/lateral hip, full length femur
- b.Previous radiographs for comparison
- Possible CT to evaluate version, bone loss
- Possible MARS MRI to evaluate for pseudotumor for MOM
- Determine revision implants
- A. Acetabular components – hemispherical cups, revision cups, metal augments, allograft, cage, cup cage, jumbo cups
- B. Liner – lipped liner, lateralized liner, constrained liner
- C. Heads – increasing head sizes, dual mobility
- D. Femoral components – proximally-porous coated, fully porous coated diaphyseal fitting, modular tapered, cemented, cemented with impaction grafting, proximal femoral replacement, APC
- E.Augments – claw plates, cables, wires, plates, strut graft
- Surgical steps
* See separate flashcard
4
Q
What are the surgical Steps for Revision THA
A
A. Approach
- i.Posterior approach preferred (most extensile)
B. Femoral stem removal
- i.Cementless
- Proximally coated stems – flexible and rigid osteotomes, reciprocating saw, universal extraction device, ETO
- Fully coated stems – as above, low threshold for ETO, gigli saw medially, possible stem transection with burr and remaining stem removed with trephine
- ii.Cemented
- Highly polished stems – expose the proximal portion of the stem with osteotomes, burr, oscillating saw then retrograde blows with universal extraction device or implant specific device
- Textured stems – expose proximal portion and disrupt the prosthesis cement interface proximally with flexible osteotomes then retrograde blows
- ETO as necessary
- Cement removal with crochet hooks, curettes, osteotomes, ultrasonic cement removal
C. Acetabulum removal
- i.Cementless acetabulum – explant system (rotating blades), curved osteotomes, screw removal
- ii.Cemented all poly – curved osteotome to dislodge poly, ream poly, remaining cement removed piecemeal
D.Reconstruction
- i.Femoral implants
- 1.Based on bone loss – Paprosky classification
- ii.Acetabular implants
- 1.Based on bone loss – Paprosky classification
- iii.Mindful of version, offset, soft tissue tension, leg lengths, stability
5
Q
What are the key steps in performing an ETO?
[Eur J Orthop Surg Traumatol (2016) 26:231–245]
A
1.Approach – posterior (can be done from a lateral approach)
- A. Fascia opened along posterior border of vastus lateralis
- B. Vastus lateralis is elevated off the femur just anterior to linea aspera
- C. Gluteus maximus insertion may be released
- Length of osteotomy – 10-15cm
* A. Generally just proximal to the tip of the stem but depends on type of stem and location of fixation - Osteotomy
- A. 1/3 the diameter of the femur
- B. Start with posterior osteotomy
- C.Distal osteotomy is transverse
- D.Anterior osteotomy completed from distal to proximal
- E.Osteotomy is opened posteriorly hinging on the anterior soft tissue
- Implant post-ETO – extensively porous coated distally fitting implants
- Fixation
- A. ETO is contoured medially to fit the revision stem
- B. Wires, cables, cable-plate systems are acceptable
- C. Tighten wires/cables distal to proximal
6.Postop protocol
- A. 6 weeks TTWB
- B. 6 weeks partial to full WB
- C.No active abduction, active SLR or strengthening for 12 weeks
6
Q
What are the principles of revision TKA?
[JAAOS 2017;25:348-357]
A
- Rebuild the tibial platform
* Make a fresh cut perpendicular to the mechanical axis of the tibia - 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
- Reestablish the extension gap
* Distal femoral implant should be at native joint line (use above references)
7
Q
In revision TKA what landmarks can be used to restore the joint line?
[JAAOS 2017;25:348-357]
A
- Lateral epicondyle = 25mm proximal
- Medial epicondyle = 30mm proximal
- Adductor tubercle = 40-45mm proximal
- Inferior patellar pole = 10mm proximal
- Meniscal scar
- Tip of fibula = 15mm distal
8
Q
In revision TKA what implants should be considered?
[JAAOS 2017;25:348-357]
A
- Posterior stabilized
* Indication – intact collateral, no varus/valgus instability - Unlinked constrained (varus/valgus constrained liner)
- Indication – mild to moderate varus/valgus instability
- Functions to limit rotation, M-L translation, varus/valgus angulation
- Rotating hinge
* Indicated for patients with bone loss and compromised collateral ligaments, compromised extensor mechanism or severe flexion-extension mismatch - Modular segmental (megaprosthesis)
9
Q
What other implant options should be considered to deal with bone loss in revision TKA?
[JAAOS 2017;25:348-357]
A
- Stems
- Bypass deficient metaphyseal bone and engage the diaphysis
- Can be cemented, cementless, or hybrid
- Cement
* Indication = <5mm defect affecting <50% of bone surface area - Cement and screw
* Indication = 5-10mm defect - Impaction grafting
- Advantage
- Restores bone stock
- Cost effective
- Disadvantage
- Technically difficult
- Risk of intraop fracture
- Disease transmission
- Infection
- Graft resorption
- Can use in contained and uncontained defects (with mesh)
- Impact graft with trial stem in place then cement final stem
- Bulk structural allograft
- Advantages – good initial support, restores bone stock
- Disadvantage – prolonged surgical time, nonunion, delayed union, disease transmission, infection, graft resorption
- Femoral head allograft is commonly used (tibia is prepared with acetabular reamer, graft is fixed with cancellous screw)
- 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
- Metaphyseal cones and sleeves
- Advantages
- Fills large defects
- Immediate structural support
- Disadvantages
- Expense
- No bone restoration
- Requires additional bone resection
- Difficult removal if revision required
- The primary difference between trabecular metal cones and metaphyseal sleeves is that the interface of the sleeve with the implant is created via a Morse tapered junction rather than with cement. [JAAOS 2011;19:311-318]
10
Q
What are the advantages and disadvantages of uncemented vs. cemented stems in revision TKA?
A
- 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
- Uncemented
- Difficult removal
- Advantages
- Obtain correct limb alignment
- Disadvantages
- Require offset options
- Long stems required to engage diaphysis
- Risk of iatrogenic fracture
- End-of-stem pain
11
Q
What is the approach to femoral bone loss in revision TKA?
[JAAOS 2017;25:348-357]
A
- Assess integrity of collateral ligaments
* If compromised = manage with increased constraint (rotating hinge or megaprosthesis) - 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
12
Q
What is the approach to tibial bone loss in revision TKA?
[JAAOS 2017;25:348-357]
A
- Assess integrity of the tibial tuberosity
* If compromised = manage with increased constraint (rotating hinge or megaprosthesis) - 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
13
Q
What are the indications for femoral revision in THA?
[J Am Acad Orthop Surg 2013;21: 601-612]
A
- Aseptic loosening
- Infection
- Osteolysis
- Periprosthetic fracture
- Component malposition
- Catastrophic implant failure
14
Q
What is the Paprosky classification for femoral bone loss?
[J Am Acad Orthop Surg 2013;21: 601-612]
A
- Type I - minimal proximal metaphyseal bone loss
- Type II - moderate to severe proximal metaphyseal bone loss
- Type IIIA - severe proximal metadiaphyseal bone loss with ≥4cm of isthmus/diaphysis intact
- Type IIIB - severe proximal metadiaphyseal bone loss with <4cm of isthmus/diaphysis intact
- Type IV - severe metadiaphyseal bone loss with no intact isthmus/diaphysis
16
Q
What are the reconstruction options for each Paprosky type of femoral bone loss?
A
- Type I - uncemented proximal fitting stem
- Type II - extensively porous-coated diaphyseal fitting stem
- Type IIIA - extensively porous-coated diaphyseal fitting stem
- Type IIIB - modular tapered stem
- Type IV - impaction grafting plus cemented stem OR APC stem
17
Q
In the setting of loose femoral components (in THA) what is the observed proximal femoral remodeling?
[JAAOS 2013;21: 601-612]
A
Varus and retroversion
18
Q
What is the most common approach used for femoral stem revision in THA?
[JAAOS 2013;21: 601-612]
A
Posterolateral
19
Q
What is the indication for an ETO when revising the femurin THA?
[JAAOS 2013;21: 601-612][Instr. Course Lec. 2004]
A
- Significant varus remodeling
- Well-fixed uncemented stem
- Long column of cement below the stem
- Abductor tension adjustment
- Exposure of complicated acetabular reconstructions
20
Q
When is an ETO indicated prior to hip dislocation (in revision THA)?
A
When dislocation is difficult and risks iatrogenic fracture
- HO, protrusion, ankylosis, stiffness
26
Q
What is the Paprosky Classification of acetabular bone loss in THA (based on location or migration of the hip centre of rotation, degree of teardrop destruction, amount of ischial osteolysis, integrity of Kohler line)?[J Am Acad Orthop Surg 2013;21] 128-139
A
Type I - minimal bone loss
Type IIA - superomedial bone loss (intact rim)
- <3cm of superior hip migration
Type IIB - superolateral bone loss (superior rim not intact)
- <3cm of superior hip migration
Type IIC - medial wall bone loss
- Moderate teardrop osteolysis and disruption of Kohler’s line
Type IIIA - “up and out”
- 30-60% superolateral rim loss (10-2 o’clock)
- >3cm superolateral hip migration
- Moderate teardrop and ischial osteolysis
- Kohler’s line intact
Type IIIB - “up and in”
- >60% acetabular bone loss (9-5 o’clock)
- Superomedial hip migration >3cm
- Severe ischial and teardrop osteolysis
- Complete disruption of Kohler’s line
- May have pelvic discontinuity
***NOTE:
- Kohler’s Line —integrity of medial wall and superior anterior column
- Acetabular Tear Drop — integrity of medial wall and inferior portion of anterior and posterior column
- Ischial Lysis —integrity of posterior wall and posterior column
- Vertical Migration —integrity of superior dome
28
Q
What is the AAOS Classification System of acetabular bone loss?
[J Bone Joint Surg Am. 2016;98:233-42]
A
Type I - Segmental
- Loss of part of the acetabular rim or medial wall
Type II - Cavitary
- Volumetric loss in the osseous substance of the acetabular cavity
Type III - combined deficiency
- Combination of segmental and cavitary
Type IV - pelvic discontinuity
- Complete separation between the superior and inferior aspects of the acetabulum
Type V - arthrodesis
43
Q
What are the technical aspects of cementing a liner into a well fixed acetabular component?
[JAAOS 2017;25:288-296]
A
- Prepare the acetabular component by using a high speed burr to score radial and circumferential grooves (~2mm in width and depth)
- If using a liner not designed for cementing it should be prepared with similar grooves on the backside
* Ensure the poly is of adequate thickness to allow for the grooves - The cement mantel should be ~2mm thick
44
Q
What are the technical aspects of cementing a liner into a well fixed acetabular component?
[JAAOS 2017;25:288-296]
A
- Prepare the acetabular component by using a high speed burr to score radial and circumferential grooves (~2mm in width and depth)
- If using a liner not designed for cementing it should be prepared with similar grooves on the backside
* Ensure the poly is of adequate thickness to allow for the grooves - The cement mantel should be ~2mm thick
47
Q
What are the technical aspects of cementing a liner into a well fixed acetabular component?
[JAAOS 2017;25:288-296]
A
- Prepare the acetabular component by using a high speed burr to score radial and circumferential grooves (~2mm in width and depth)
- If using a liner not designed for cementing it should be prepared with similar grooves on the backside
* Ensure the poly is of adequate thickness to allow for the grooves - The cement mantel should be ~2mm thick
