Reconstruction Flashcards
Describe deformity seen. When performing TKR to either knees, how would you perform soft tissue balancing for correction of this deformity?
There is varus deformity, a coronal plane deformity.
There is concave (ST tight) and convex side (ST loose/strecthed).
Always start with tight side/ concave side first, which is medial side in this deformity.
Sequence of medial compartment release
1. Osteophytes
2. Deep MCL & Medial knee capsule
3. Posterior Medial Corner - capsule, semimembranosus.
4. Superficial MCL
i) Posterior oblique portion - if medial extension tightness
ii) Anterior portion - if medial flexion tightness
Describe deformity seen. When performing TKR to either knees, how would you perform soft tissue balancing for correction of this deformity?
On this xray, there is valgus deformity in the coronal plane.
There is concave (ST tight) and convex side (ST loose/stretched).
Always start ST release at the tight side/ concave side first, which is lateral side in this deformity.
With the knee in extension
Sequence of lateral compartment release
1. Osteophytes
2. Lateral capsule
3. Iliotibial band - tight in extension
then flex the knee
4. Popliteus - tight in flexion
5. Lateral collateral ligament - always last
What influences sagittal plane balancing in TKA?
Flexion gap
- posterior cut of femur
- tibial cut
- PCL
Extension gap
- distal cut of femur
- tibial cut
- posterior capsule
Name common complications following a TKA (Post-op complications).
Acute complications:
I
Chronic complications:
Femoral notching –> leading to fracture
Peroneal nerve palsy, esp in valgus flexion deformity.
Patella fracture
List down potential complications during TKA (Intra-op complications)?
How to reduce these complications?
- *A) Vascular injury**
i) direct laceration
ii) blunt trauma from posterior retractor placement
iii) thrombosis
Reducing complications:
i) Flexion of knee during bone cuts, flexion bring artery farther from the knee.
ii) Stay medial to PCL, using single prong retractors, do not insert retractor more >1cm into posterior soft tissues.
iii) Tourniquet timee not beyond 2 hours.
B) Peroneal nerve palsy
Reducing complication: no overzealous retraction at lateral side.
C) Extensor mechanism rupture
Who are at risk of peroneal nerve injury following a TKA?
Patients
- Who had pre op neuropathy- centrally or peripherally.
- With large deformity correction like valgus flexion deformity.
- Who used tourniquet > 120 minutes.
- Who has abberant retractor placement during TKA.
- Who had post-operative epidural anaesthesia.
What are the approaches to arthrotomy of the knee and their indications?
How would you performed them?
Advantages and disadvantages?
Medial parapatellar
Midvastus
Subvastus
How would you performed the various arthrotomy to the knee?
Advantages and disadvantages?
- Describe this limb.
- What are the potential complications encountered during a knee replacement surgery?
- How to reduce these complications?
- There is right genu valgus and left genu varus with right knee in flexion when left knee is in full extension.
- Potential complications i) Injury to common peroneal nerve (risk increase than normal native knee because there is valgus with more release performed at lateral side, and there is flexion with more release that has to be performed posteriorly). ii) collateral ligament insufficiencies especially at the medial side.
- i) keep right knee in slight flexion post operatively. ii) use constraint implants.
CR TKA:
- What is this prosthesis?
- What is the design category and feature of this prosthesis?
- What is the advantages of this type of prosthesis?
- What is the disadvantages of this type of prosthesis?
- Cruciate-retaining total knee arthroplasty.
- Least constrained type of TKA, where ACL is removed, PCL is retained. On lateral view, can appreciate pegs instead of a box shape for the retained PCL, PE insert is also more flat to allow the femur to roll back onto the posterior part of bearing.
- Advantages: i) Retaining PCL allows more bone conserving. ii) Keeping PCL helps to regulate flexion stability and keep flexion gap smaller. iii)Allows more consistent joint line restoration due to ii. iv) Allows more propioception feedback.iii) PCL tension influences femoral rollback, which is the progressive posterior change in femoral-tibial contact point as the knee moves into flexion.
- Disadvantages: i) Harder to balance with severe deformities (avoid in varus >10 degs, valgus >15 degs). ii) Tight PCL in flexion will lead to increased PE wear. iii) Increase PE wear, increase particle debris, causing osteolysis, leading to dysruption of PCL from bony attachments, resulting in knee instability and repetitive subluxation. iv) Paradoxical forward sliding as knee flexes. PCL prevents posterior translation of the tibia relative to the femur but with ACL gone, tibia can still slide forward, causing sliding wear on PE insert.
CS TKA:
- What is this prosthesis?
- What is the design category and feature of this prosthesis?
- What is the advantages of this type of prosthesis?
- What is the disadvantages of this type of prosthesis?
- Posterior stabilised TKA.
- Cruciate retaining TKA, has spine and cam mechanism in the posterior aspect of the knee, the cam is part of the femoral component between the two posterior femoral condyles, the PE insert has a post which the cam engages onto during flexion thus preventing anterior translation of the femur on the tibia (a function typically by PCL), no posterior roll back as like a normal knee as cam and post control rollback, PE inserts are more dished/congruent to the femoral condyle shape.
- Advantages: i) Allows easier balancing in severe coronal deformities as ACL and PCL removed (balancing only required in one plane). ii)There is controlled flexion kinematics with spine and cam mechanism, so less sliding wear.
- Disadvantages: i) Risk of dislocation due to femoral cam jump when flexion gap is too loose and with any varus/valgus stress applied when knee is flexed, thus allowing femoral cam to rotate in front of the post and rests in front of it. ii) Patella clunk syndrome due to scar tissue getting caught in the box. ii) Tibial post wear and breakage. iii) More bone is removed from middle of distal femur. iv) Flexion gap is bigger as PCL is removed, to in order to balance the extension gap additional distal femur is removed and so causing joint line elevation and subsequently patella baja
Classification: Dorr
- What is the Dorr classification?
Dorr classification
- is used to evaluate the quality of proximal femoral bone according to radiographic, biochemical and histologic data.
- where it describes the relationship of the diameter of proximal femoral canal relative to diameter of the femoral diaphysis.
- by measuring the ratio between the canal diameter of the femoral diaphysis 10 cm distal to mid point of the Lesser Trochanter and canal diameter at mid point of the Lesser Trochanter.
- and as such divide into 3 types, which is then used as a guide indications for cemented or uncemented femoral component fixation.
- Type A: ratio <0.5, thick bone cortices in AP and lateral views with narrow canal, referred to as “champagne flute”, commonly found in younger patients. Femoral fixation type: Uncemented.
- Type B: ratio 0.5 to 0.75, thining of cortices seen typically at medial and posterior on lateral view, resulting in a widened residual funnel shape canal. Femoral fixation type: Uncemented.
- Type C: >0.75, thinning of cortices on both views, stovepipe shape. Femoral fixation type: Cemented.
Hip THA
Describe parts of a THA.
A. Reamed portion of the acetabulum to fit the acetabular cup.
B. Acetabular cup
- in metal or PE material
- porous-coated for cementless
- smooth-finish for cemented
C. Cup Liner
- in PE or ceramic material
- PE-metal bearing
- Ceramic-ceramic bearing
D. Femoral head ball
- in metal or ceramic material
E. Femoral stem
- for cementless and cemented
- What type of bearing in THA is used in this image?
- What is the mechanical properties of this component used?
- When will you use this type of bearing for THA
- What are the disadvantages of this type of bearing?
- How does this material provide lubrication?
- Ceramic-on-ceramic.
- Mechanical properties of ceramic
- Best wear properties of all bearing surfaces
- Lowest coefficient of friction of all bearing surfaces
- Inert particles, most bio-tolerability, so no cancer risk.
- Used in young patients < 60 years, who are still active, whose estimated femoral head is 32-36 mm.
- Disadvantages
- More expensive than Metal on PE
- Worst mechanical properties: alumina is brittle, low fracture toughness - high risk of breakge/fracture at liner and head.
- If fractured, no options for PE liner as microscopic ceramic shards remain and are severely abrasive. can cause rapid PE wear.
- Can give rise to audible squeaking
- Limitation in head size; only can have smaller head size which has less stability and range of motion.
- Limitation in head length, limit hip offset, can lead to hip impingement and instability.
- Less modularity with fewer neck length options
- Can result in stripe wear - caused by contact between femoral head and rim of the cup during partial subluxation, appears crescent shaped line on femoral head.
- Lubrication potential
Ceramic-on-ceramic bearing show superior lubrication potential compared to hard-on-hard bearings that work with at least one articulating metal component.
Less surface roughness compared to metal
0.006 vs 0.01 micrometer
- What type of bearing in THA is used in this image?
- What is the mechanical properties of this component used?
- What are the complications that can arise from using this material?
- How would you address the complications that can occur following its use?
- Metal on metal
- Mechanical properties
- Better wear properties than Metal on Poly.
- Lower liner wear rate
- very low volumetric & linear wear
- debris particle much smaller (0.015-0.12 micrometre) but more numerous than Metal on Poly
- Run-in wear- higher wear rate seen within the 1st million cycles, ~ 1 year of high activity. After that, wear rate reduces to a lower steady state rate.
- Larger head allows for increased ROM before impingement.
- Complications
i) Hypersensitivity response
- associated with Nickle ion
- pain and ache starts soon after post op recovery, persistent with 24/7 characteristics.
ii) Adverse local soft tissue reaction (ALTR)
- occur 3-5 years
- due to continued debris formation
- pain and ache, may have osteolysis around the implant
- eventually may form pseudotumour (mass or cystic fluid collection)
- May lead to destruction of abductors.
iii) Ion metals can cross placenta, so avoid use in women of child bearing age.
iv) Ion metaks not eliminated in renal failure patiets.
4. Addressing complications
i) Hypersensitivity response
- rule out infection, hip aspiration -→ low WCC
- Replace with nickel free implant (remove cobalt chromium allow metal)
ii) Adverse local soft tissue reaction (ALTR)
- send tissue for HPE - ALVAL (aseptic lymphocyte-dominanted vasculitis-associated lesion) will be seen.
- Remove Co-Cr bearing
- Revise loose implants
- Radical debridement of necrotic and toxic soft tissue
- Use titanium allow implants/ Ceramic-PE/Ceramic-Cer bearing.
- Define “Wear” in arthroplasty.
- Describe mechanism of wear.
- Give examples of wear in arthroplasty
- Wear
- refers to the loss of prosthetic material from the interface of articulating surfaces, and can be due to abrasion, adhesion, or 3rd body particles.
- prosthetic debris mechanically released from the surface of prosthetic joints deposits in periprosthetic tissue.
- induces an immune response that favors bone catabolism/osteolysis, resulting in loosening of prostheses with eventual failure or fracture.
2,3. Examples of wear & mechanism
a) Adhesive wear
- when anatomic forces occuring between the 2 opposing surfaces are stronger than inherent strength of either material.
- microscopically, small portions of PE surface sticks to prosthesis and debris gets pulled off.
- leading to creation of pits and voids in PE surface.
b) Abrasive wear
- cheese grater effect of femoral head surface prosthesis scraping off PE surface.
c) 3rd body particles
- particles within joint space get between head and PE cup, causing abrasion and wear.
- sources:
cement debris
metal debris from cup/stem/modular junctions
hydroxyapatite debris from implant surfaces
abrasive material introduced during prosthetic joint implantation.
d) Volumetric wear
- determines the number of debris particles generated.
- directly related to square of the radius of the head.
e) Linear wear
- distance the prosthesis has penetrated the liner
- Describe the plain radiograph.
- Explain why this happened?
- How may patient present clinically?
- How will you manage such a patient?
- Evidence of loosening of femoral stem.
lucency > 2 mm at cement-bone or metal-bone interface
(Cannot use Barrack and Harris classification as this is used for commenting on quality of cementation for primary THR)
Septic vs aseptic: need laboratory IX- ESR and CRP normal
- Wear occuring between prosthesis interfaces
- → prosthesis micromotion
- → debris generation
- → phagocytosis by macrophages, becomes activated, release proimflammatory cytokines causing additional macrophages recruitments.
- → more proimflammatory cytokines reaches osteoblast
- → upregulate production of RANKL. More RANKL/osteoprotegrin ratio (OPG blocks RANKL)
- → RANKL attaches to RANKL receptors on osteoclast surface, induces osteoclastogenesis -→ bone resorption -→ implant loosening
- inflammatory response generated by debris results in hydrostatic pressure build up within the joint.
- debris is disseminated throughout the effective joint space, which is any contigous area around the joint where implant touches bone.
- Osteolysis can occur anywhere within the effective joint space.
- As fluid moves in path of least resistance, areas not well-sealed by biologic intergration will allow particle dissemination -→ loosening between cement mantle-bone.
- Clinical presentation
Symptoms:
- may have minimal pain with ROM
- increased pain with weight bearing
If THA aseptic loosening- pain at groin, thigh, knee can occur with activity
Signs:
Radiographic evidence seen about 10 years post op
i) Femoral component
- lucency > 2mm at cement-bone interfaces
- Thinned out cement mantle noted with direct contact metal-bone interfaces.
- Endosteal scalloping in femoral endosteal canal.
- subsidence > 1 cm (need to confirm with previous film)
ii) Acetabular component
- migration
- Change in position/inclination
- Asymmetric position and superior position of the femoral head within acetabular cup - wearing of PE liner
- Round lytic lesions behind acetabular cup with screw holes and screws.
Laboratory IX- no infection
*** Osteolytic lesions spotted within 2-3 years post op is most likely result of infection.
- Treatment of aseptic loosening of THA
- depends on patient’s symptoms and extent of osteolysis
i) Non-operative
- observation
- stable implant
- minimal symptoms
ii) Operative
- revision THA
- pain
- extensive osteolysis that would compromise revision surgery in future.
Definition of aseptic loosening:
Macrophage-induced inflammatory response that results in bone loss and implant loosening in the abscence of an infection.
Patient had undergone right knee TKA 12 years ago, now complaining of sudden onset pain at the operated knee on ambulation. This is the plain radiograph of the symptomatic knee.
- Describe the plain radiograph.
- How will you investigate this patient to arrive to your clinical diagnosis?
- What is the cause of this patient’s symptoms?
- How will you manage this patient’s pain?
- Plain radiograph
Right knee prosthesis is subluxed
Evidence of femoral and tibial osteolysis
- Tibia AP - > 2 mm radiolucent area beneath the tibial plate and cement interface.
- Femoral Lat - > 2 mm radiolucent area in the posterior condyles between femoral component and cement interface.
Change in position of implant - tibial component has flexed and varus subsidence.
** cement cracking/fragmentation and delamination
- IX - ESR and CRP to rule out infection
Clinically- afebrile, no local signs of infection (erythema, warmth, tenderness), only minimal pain on ROM and increased pain on weight bearing.
- Aseptic loosening of TKA prosthesis
- Revision TKA
if bone defects > 10 mm
+ prosthetic metal wedges/augments (if elderly, inactive)
+bone graft (younger patients, active)
Re picture attached:
The classic loosening of the implant in worst instances begins with a delamination pull-away of the cement on the posterior keel, followed by failure of the proximal posterior tibial surfaces; Compare the positioning immediately post-op (a) verses that at 6 months, where the slope changes from 7o to 9o and the implant subsides (b)
https://jeo-esska.springeropen.com/articles/10.1186/s40634-020-00243-9
This patient has undergone single knee TKA. Post operatively, she experience pain in her knees. Plain radiograph is done and is shown.
- Describe the plain radiograph.
- What is the problem.
- How to avoid this problem intra-operatively.
- How to manage this problem intra-operatively.
- How to manage this problem post-operatively.
- Skyline/tangential view of the knee with anterior surface of femoral prosthesis and patella in view.
Unable to comment on femoral prosthesis.
Patella tilt with lateralisation noted, not within the trochlear groove, articular surface showed evidence of pateloplasty.
- Patella maltracking.
- Avoid- Intra-operative
DO NOT
- internally rotate femoral and tibial component.
- medialise femoral and tibial component.
- place laterally the patellar component.
INSTEAD SHOULD DO
- externally rotate femoral 3 degrees
- keep femoral component slightly lateral
- neutral placement of tibial component, centered at medial ⅓rd of tibial tubercle
- place medially or at neutral the patellar component.
- Tackle - Intra-operative
- release tourniquet to check for maltracking.
- if still present, perform lateral release (manipulate soft tissue)
Patient presents with worsening hip pain following MVA 6 months ago where he did not seek medical attention.
- Describe what you see on his plain radiograph.
- What is your impression?
- How will you manage him?
- Management
Aims: to obtain a pain free and stable hip
THR with constraints component
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5653596/
Due to neglected hip, AVN is 100%
Global softening of femoral head after one year of neglected dislocation warrants replacement of the femoral head.
Advantages of cruciate-retaining prosthesis?
PCL-retaining:
- improved stability
- reduced shear stresses at the fixation interface
- improved proprioception
- more efficient gait patterns during level walking and stair climbing; moreover
- preserve femoral rollback, which improves extensor efficiency by lengthening the moment arm and improves the range of flexion by minimizing the potential for impingement of the femur on the tibial component, reducing loosening and excessive polyethylene wear.
Name the types of knee replacement implants available.
- Non-constrained implant
* Cruciate retaining (CR)
* Cruciate sacrificing/substituting
i) Anterior stabilised (AS)
ii) Posterior stabilised (PS)
Further classified into
a) Unicompartmental
- When only 1 compartment needs to be replaced.
- Example: tibial-femoral UKA (medial/lateral), patelllo-femoral UKA (native trochlear replaced by metal trochlear, patella component is PE)
- Criteria: intact ACL, one compartment OA
b) Bicompartmental
- Medial and lateral tibial and femoral compartments are replaced at the same time.
- Native patella retained.
- Example: TKA
c) Tricompartmental
* Medial and lateral tibial and femoral compartments + patellofemoral compartments are replaced at the same time.
2. Constraint implants
Femoral and tibial components are linked together via a hinge/link mechanism in the horizontal plane to accommodate for loss of soft tissue support.
Examples:
i) Non-hinge prosthesis
with High tibial post
ii) Hinge prosthesis
with rotating tibial platform
without rotating tibial platform
- Name this implant and its respective components.
- List advantages and disadvantages of this implant.
- Criteria for using this implant.
- Non-constraint Cruciate-retaining prosthesis with mobile-bearing design.
* Implant feature
thin black arrow - metal bicondylar femoral component.
thick black arrow - polyethylene insert
hollow arrow - metal tibial baseplate
- Advantage& Disadvantages
Advantages:
i) Retaining PCL allows more bone conserving.
ii) Keeping PCL helps to regulate flexion stability and keep flexion gap smaller.
iii) Allows more consistent joint line restoration due to ii.
iv) Allows more propioception feedback.
iii) PCL tension influences femoral rollback, which is the progressive posterior change in femoral-tibial contact point as the knee moves into flexion, there is posterior translation the femur with progressive flexion.
Disadvantages:
i) Harder to balance with severe deformities (avoid in varus >10 degs, valgus >15 degs).
ii) Tight PCL in flexion will lead to increased PE wear.
iii) Increase PE wear, increase particle debris, causing osteolysis, leading to dysruption of PCL from bony attachments, resulting in knee instability and repetitive subluxation.
iv) Paradoxical forward sliding as knee flexes. PCL prevents posterior translation of the tibia relative to the femur but with ACL gone, tibia can still slide forward, causing sliding wear on PE insert.
3. Criteria for use
Intact PCL
Coronal plane deformity minimal - varus < 10, valgus < 15
No collateral ligament laxity
- Name this implant and its respective components.
- List advantages and disadvantages of this implant.
- Criteria for using this implant.
- Non-constrained, posterior stabilised TKA with mobile-bearing design.
* Feature:
Metal femoral component has a cam
PE has a higher tibial post and are more dished/congruent to the femoral condyle shape.
Metal tibial base plate
Whole prostheses has spine and cam mechanism in the posterior aspect of the knee.
- the cam is part of the femoral component between the two posterior femoral condyles
- the PE insert has a post which the cam engages onto during flexion thus preventing anterior translation of the femur on the tibia (a function typically by PCL), no posterior roll back as like a normal knee as cam and post control rollback.
- Advantages:
i) Allows easier balancing in severe coronal deformities as ACL and PCL removed (balancing only required in one plane).
ii) There is controlled flexion kinematics with spine and cam mechanism, so less sliding wear.
Disadvantages:
i) Risk of dislocation due to femoral cam jump when flexion gap is too loose and with any varus/valgus stress applied when knee is flexed, thus allowing femoral cam to rotate in front of the post and rests in front of it.
ii) Patella clunk syndrome due to scar tissue (nodule) getting caught in the box as knee moves from flexion into extension, at 30-45 degrees range.
ii) Tibial post wear and breakage.
iii) More bone is removed from middle of distal femur.
iv) Flexion gap is bigger as PCL is removed, to in order to balance the extension gap additional distal femur is removed and so causing joint line elevation and subsequently patella baja.
3. Criteria for use
- Cases with PCL rupture or attenuation eg trauma.
- Inflammatory arthritis - PCL is at risk for rupture as disease progresses.
- Patellectomy hx
- Name this implant and its respective components.
- List advantages and disadvantages of this implant.
- Criteria for using this implant.
- Unicompartmental arthroplasty of the medial tibio-femoral joint.
2.
Advantages:
- lower complications, morbidity, mortality- significantly lower incidence of thromboembolism, infection, stroke, MI.
- faster recovery, shorter hospitalization post op
- less blood loss and risk of transfusion
- better restoration of physiological gait pattern
Disadvantages:
- Significantly higher revision rate
aseptic loosening
progression of arthritis
PE wear
technical errors
unexplained pain
- Criteria for usage
- isolated medial compartment disease
- both ACL and PCL intact
- flexion contracture < 5 degree
- Collateral ligs intact, no contracture
- coronal angular deformity < 15 degree
- pre op ROM flexion up to 90 degree
- No evidence of OA on lateral compartment
- No active infection
- No inflammatory disease or arthropathy
- No previous history of HTO
- age < 60
- low level activity
- weight <82 kg
- no patellofemoral OA
If mobile bearing, can still be used in patients who are
- age >60 years
- high activity
- has patellofemoral OA
- presence of chondrocalcinosis on radiograph and intra op
If fixed bearing, can still be used in patients who are
- obese
Diagnosis OA based on ACR, EULAR and NICE
EULAR criteria
According to these criteria
- patients older than 40 years of age with
- movement-related joint pain
- morning knee stiffness of less than 30 min
- and functional limitations have knee OA
- if they in addition have one or more of these examination findings: Crepitus, restricted range of motion, and bony enlargement.
ACR criteria
The decision tree version of the original ACR criteria for clinical knee OA was used. According to the decision tree, patients with knee pain have OA if they fulfill one of the following groups of criteria:
1) Crepitus, morning knee stiffness of 30 min or less, and age of 38 years or above
2) Crepitus, morning stiffness of longer than 30 min, and bony enlargement
3) No crepitus, but bony enlargement
NICE criteria
patients can be diagnosed with knee OA if
- they are 45 years or older
- have movement-related joint pain
- and either no morning knee stiffness or stiffness of 30 min or less.
During TKA for a valgus knee, what are the soft tissue release for balancing performed?
In a valgus knee, contracted soft tissues are at the lateral aspect of the knee.
(The inside out technique)
The order of soft tissue release after removing osteophytes are
(with knee extended)
i) ITB - extension tightness
- through elevation from Gerdy’s tubercle
- if inadequate, can do “pie crusting” with multiple stab wounds to lenghten it.
(with knee flexed) - if still tight
ii) Popliteus
- release off anterior portion of lateral epicondyle
iii) Lateral collateral Ligament (LCL)
- release off anterior portion of lateral epicondyle
iv) Posterior lateral capsule (PLC)
- release off distal part of femur
- “Pie crusting” also can be done to lengthen
- What are the approaches commonly used in Valgus Knee TKA?
- What are the advantages and disadvantages?
- Approaches
Medial parapatellar
Lateral parapatellar
2.
Medial parapatellar:
Advantages -
Disadvantages
- difficulty to reach PLC during lateral soft tissue release
- In efforts to perform lateral releases, may lead to lateral genicular artery damage, leading to patellar necrosis.
Lateral parapatellar:
Advantages
- provides direct access to lateral retinacular and capsular ligamentous tissues for release
- offers better surgical view
Disadvantages:
- limitations in viewing the central and medial aspects of the knee
- as a result, need to perform “wafer” osteotomy of the tibial tubercle which carries risk of patellar tendon failure and nonunion.
- releases performed may leave insufficient tissue for wound closure
High Tibial Osteotomy
- What is HTO?
- What are the indications of HTO?
- What are the contraindications of HTO?
- Definition of HTO
- is a joint preserving surgical procedure
- performed in young or middle-aged active patients.
- to correct angular deformities of the knee, typically varus (can also include valgus knee)
- to prevent development or progression of unicompartmental osteoarthritis (medial) with concurrent varus deformity.
- and thus produces a postoperative valgus limb alignment with shifting the load-bearing axis of the lower limb laterally.
- in hope to delaying the need for TKA.
- Indications of HTO (based on ISAKOS)
▪Either a primary or secondary
▪Isolated single (medial/lateral) compartment degenerative arthritis - only one side joint line pain
▪with varus/valgus malalignment, < 15 degs
▪Ideally in an individual who is-young (≤ 65 years old)
Who is
- active patient
- with good active knee ROM
- without ligamentous instability.
- Non smoker
- BMI < 20
3. Contraindications of HTO - Inflammatory arthritis (eg RA)
- Flexion contracture > 15 degrees
- knee flexion <90 degrees
- procedure will need >20 degrees of correction
- Bicompartmental osteoarthritis
- Patellofemoral arthritis
- Severe single compartment OA
- Ligamentous instability
- Varus thrust during gait
Patella
- How to determine patella position on sagittal plane?
- How to determine patella position on coronal plane?
- Patella in sagittal plane.
Get plain radiograph of the knee in true lateral view with 30’ flexion
1) Insall-Salvati ratio
= ratio of patella tendon length to length of patella
- Patella alta >1.2, patella baja <0.8, mean normal =1.0
2) Caton-Deschamps ratio
= ratio of distance between distal articular facet of patella & anterior-superior corner of superior tibial epiphysis to length of articular cartilage surface of patella
- Patella alta >1.2, patella baja <0.6
3) Blackburne-Peel ratio
= ratio of line drawn from the tibial plateau to distal articular facet of patella to length of articular cartilage surface of patella
- Patella alta >1.0, patella baja <0.8
- Patella position in coronal plane
The Q-angle
- is defined as the angle between a line drawn from the anterior superior iliac spine (ASIS) to the center of the patella and a line from the center of the patella to the tibial tubercle.
- Normal Q angle should fall between 12 and 20 degrees; the males are usually at the low end of this range; while females tend to have higher measurements.
- values between 8° and 10° for men and up to 15° for women are deemed normal.
- A Q-angle greater than 15 degrees may cause the patella to sublux laterally during quadriceps con- traction.
- Which eventually results in wearing away of the cartilage on the underside of the patella which can be translated into the loosing of the articular surface of the knee
High tibial osteotomy - LCWO
- What is this procedure?
- What are the advantages of this method?
- What are the disadvantages of this method?
- Lateral closing wedge proximal tibial osteotomy
- wedge of bone removed with tibia via an anterolateral approach
- ORIF performed to lateral proximal tibia.
- Advantages
- Faster osteotomy site consolidation
- Does not need bone graft
- More stability
- Earlier weight bearing and rehab
- Disadvantages
- Require 2 tibial cuts
- Increase risk of common peroneal nerve injury
- Reduce proximal tibia bone stock
- Disruption of proximal tibia fibular joint
- Eccentricity of medullary canal for future TKA.
- Can reduce posterior tibial slope
- Can cause posterior translation of the tibia
- As such, increase strain on PCL
- Can cause knee hyperextension
- Reduce anterior stability
- May cause patella alta
High tibial osteotomy
- What is this procedure?
- What are the advantages of this method?
- What are the disadvantages of this method?
- Medial opening wedge proximal tibia osteotomy.
- Advantages
- 1 tibial cut required
- preservation of proximal tibiofibula anatomy
- Avoids risk of injury to CPN
- Preserves bone stock at proximal tibia
- Easier conversion to TKA
- Disadvantages
- Longer time to consolidation
- Longer time for weight bearing & rehab
- Need bone grafting
- Expensive as such
- Increase PTS
- Increase anterior tibial translation
- Restriction of extension
- Overload the ACL
- Reduced posterior stability
- Can cause patella baja
Knee osteoarthritis
What are the classifications available to grade knee OA?
- Ahlback grading - based on degree of joint space narrowing
- Kellgren & Lawrence -based on presence of osteophytes
Steps to performing Knee Arthroplasty (after exposure of the joint) - Tibial preparation
Use extramedullary tibial cutting guide to do this.
- Resect proximal portion of tibia at 90 degrees to long axis.
- Amount resected depends on pre-op evaluation
eg. in type 2-3 valgus deformities, need to resect less bone than normal so 6-8 mm resected from medial compartment, performed after all osteophytes removed.
- Before resection made, confirm allignment with allignment guide
- on AP: centered at middle of ankle (if want more objective- centered on the talus on AP xray)
- on lateral: parallel to tibial crest.
-Traditionally, the distal portion of the rod is moved anteriorly so that the cutting block matches the slope of the tibial plateau.
Disadvantages: - there is a very wide range of inter-individual variation
in the posterior slope of the tibial plateau in the normal knee (up to 15.5° of posterior slope).
-in many cases, the tibia plateau is eroded, making this determination inaccurate.
-More accurate method: The distance to the extramedullary guide between the cuttingsurface and the anterior skin surface simulated the preoperative planning with lateral radiograph (pic as attached)
- Once all this is in place, and ensuring adequate retraction by assistant with retractors appropriately placed, perform the proximal tibial resection using a sharp oscillating saw.
- Next the trial tibial inset is used to determine the size of tibial tray needed on the basis of AP diameter of the LATERAL tibial condyle.
