Arthroplasty Flashcards
1
Q
Options for this young (<50yo) patient with a painful right knee
A
- Exhaust concervative treatment
- PT, NSAIDS
- off loading brace
- Cortisone injections
-
Valgus producing tibial ostotomy
-
Contraindications
- Inflammatory arthritis
- Less than 90 deg flexion
- Flexion contracture > 10 deg
- Ligament instability (varus thrust)
- Lateral tibial subluxation > 1cm
- Medial compartment bone loss
- Lateral compartment joint space narrowing
-
Predictors of failure
- Smoking
- > 60
- Varus > 10
- Other arthritides
-
Contraindications
-
Closing wedge problems
- Patella baja
- Loss of posterior slope
-
Opening wedge
- Nonunion
- Loss of valgus correction
2
Q
Contraindications to HTO
A
Inflammatory arthritis
Less than 90 deg flexion
Flexion contracture > 10 deg
Ligament instability (varus thrust)
Lateral tibial subluxation > 1cm
Medial compartment bone loss
Lateral compartment joint space narrowing
3
Q
Predictors of failure of HTO
A
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Smoking
> 60
Varus > 10
Other arthritides
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4
Q
Options for this 65yo male with painful right knee?
A
-
Exhuast non-operative
- PT, NSAIDS
- cortisone injection
- offloading brace
- Cane, mobility aids
- UKA vs HTO vs TKA
-
UKA benefit over HTO and TKA
- Smaller incision
- Better knee function
- Shorter stay with less pain
-
Technique
- Do not overcorrect - can cause early failure
- Varus - correct to 1-5 deg of valgus
-
Contraindications
- ACL deficiency (strongest)
- fixed varus or valgus deformity > 10 degrees
- restricted motion
- < 90° of flexion
- fixed flexion contracture of > 10°
- joint subluxation of 5 mm or greater
- arthrosis of the additional compartment
- modest Outerbridge Stage II chondromalcia of patella is acceptable
- non-osteoarthritis arthritis
- younger high activity patients and heavy laborers
- overweight patients (> 90 kg)
-
Selection criteria
- Pain must be localized to the compartment being replaced
- Anterior knee pain means patellofemoral disease
- Global pain means tricompartmental disease
-
Complications
- Stress fractures
- best visualized on bone scan
- Usually on the tibial side
- Tibial component collapse
- poor mechanical properties of the bone
- Failure
- Overcorreciton
- Stress fractures
- Undercorrection
- Fixed-bearing (loosening)
- Mobile bearing (diseae progression)
- Patellar impingment (requires revision to TKA)
-
5
Q
Normal alignment of the knee
A
Lateral proximal femoral angle: 90 degrees
Mechanical Lateral distal femoral angle: 88 degrees
Anatomic Lateral distal femoral angle: 81 degrees
Medial proximal tibial angle: 87 degrees
Lateral distal tibial angle: 89 degrees
6
Q
What is this depicting and what are your considerations when measuring the deformity?
A
CORA - center of rotation of angulation
- Draw a line threw the axis of the distal and proximal end
- If there is only angulation - will occur at the apex of deformity
- If there is combined translation - will occur at a distance equal to the amount of translation deformity
- If angulation is seen on both AP and lateral, the true angulation will be larger than that seen on either XR
- When you don’t see angulation in one plane, but you do on the other - this is the true angular deformity
7
Q
What is your appraoch to this patient?
A
-
History
- Take a complete and ample history
- Pain, functional issues, issues in other joints
- Previous surgeries, trauma
- PMHx, meds, all
-
Physical
- Look
- Gait, measure alignment and deformity
- Feel
- Assess stability of the hip, knee, ankle/foot
- Move
- ROM, contractures
- Full NV exam
- Look
-
Imaging
- Radiographs - full length standing AP/Lat
-
Indications for surgery
- Ligamentous laxity on the concave side
- LLD > 2cm
- Uniconylar OA of the knee
- Inability to place the foot in a plantigrade position
-
Conservative
- Unloading brace
- Shoe lift/orthoses
- Appropriate analgesia
-
Considerations
- Healing potential
- Should be done in an area with better healing potential
- Can accept some translation as long as the deformity is anticipated
- Leg length discrepancy - affected by both closing/opening and varus/valgus, the affect is combined
- Closing wedge can relatively lengthen ligaments and tendons
- Opening wedge with lengthen = half the base of the triangle
- Healing potential
- Varus correction will produce lengthening
- This will decrease as you go more distal
- Valgus produces shortening
8
Q
Technical goals of TKA
A
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- **restore mechanical alignment **(mechanical alignment of 0°)
- restore joint line ( allows proper function of preserved ligaments. e.g., pcl)
- balanced ligaments (correct flexion and extension gaps)
- maintain normal Q angle (ensures proper patellar femoral tacking)
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9
Q
You are planning a TKA for this patient. What are the order of releases
A
- osteophytes
- deep MCL (usually osteophytes and deep MCL is sufficient release)
-
Posteromedial corner
- Semimembranosus
- capsule
-
superfical MCL
- can find as it blends into pes anserine complex
- can not completely release or will have valgus instability (requires constrained prosthesis). Therefore perform subperiosteal elevation only
- Differential release: performed with two component of superficial MCL
- posterior oblique portion is tight in extension (release if tight in extension)
- anterior portion is tight in flexion (release if tight in flexion)
- PCL
10
Q
Order of release for a flexion contracture
A
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- Order of posterior release
- osteophytes
- posterior capsule
- gastronemius muscles (medial and lateral)
- You do not want to address by removing too much tibia
- will change joint line and lead to patella alta
- Performed with the knee flexed so there is less risk to the popliteal artery
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11
Q
Important considerations for planning your TKA cuts
A
Femur
- uses intramedullary guide, if can’t get this then use CT guided (post DFVO, trauma etc)
-
Distal femur valgus cut (5-7° from AAF )
- jig measures 6 degrees from femoral guide (anatomic axis)
- will vary if people are very tall (VCA < 5°) or very short (VCA > 7°)
-
Posterior referencing with femoral cut
- 3 deg ER (normal DR is 3 deg IR)
- otherwise will internally rotate your component
- should be parallel to interchondylar axis
- be careful with hypoplasia of the lateral femoral condyle, you can put the prosthesis into IR with a posterior reference system
Tibia
- Cut should be perpendicular to mechanical axis
- Can use intramedullary, unless there is deformity then need to use extramedullary
12
Q
This patient comes in with knee pain. What is the most common complications of TKA? How can you prevent it?
A
- Abnormal patellar tracking, although not the most serious, is the most common complication of TKA.
- The most important variable in proper patellar tracking is preservation of a normal Q angle (11 +/- 7°)
- the Q angle is defined as angle between axis of extensor mechanism (ASIS to center of patella) and axis of patellar tendon(center of patella to tibial tuberosity)
- Any increase in the Q angle will lead to increased lateral subluxation forces on the patella relative to the trochlear groove, which can lead to pain and mechanical symptoms, accelerated wear, and even dislocation.
- Common errors include:
- internal rotation of the femoral prosthesis
- medialization of the femoral component
- internal rotation of the tibial prosthesis
- placing the patellar prosthesis lateral on the patella
13
Q
Where should the joint line be in TKA? What problems can you run into if you move it
A
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-
Normal joint line
- 1 cm above fibula
- 2 fingerbreaths about tibial tuberosity
- **elevating the joint line **(> 8mm leads to motion problems) and can lead to
- mid-flexion instability
- patellofemoral tracking problems
- an “equivalent” to patella baja
-
lowering joint line
- lack of full extension
- flexion instability
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14
Q
Saggital balancing. Go. All of it. You have 30 sec.
A
15
Q
You are planning a TKA on this patient. What is your order of release. What are some important considerations?
A
-
Classification
- Stage 1 - not correctable
- Stage 2 - > 10 deg, not correctable
- Stage 3 - severe deformity, possibly incompetent MCL, severe bone loss
-
Order of Release
- osteophytes
- lateral capsule
- iliotibial band if tight in extension (release if tight in extension)
- with Z-plasy or release off Gerdy’s tubercle
- popliteus if tight in flexion (release if tight in flexion
- for severe deformities release both the iliotibial band and the popliteus
- LCL
- some authors prefer to release this structure first if tight in both flexion and extension
- others prefer this should be the last structure to release, if you need to release it consider of constrained prosthesis
-
Considerations
- Coronal balancing - older patient can use CCK, younger patient want to take less bone, but still want to do a primary knee
- peroneal nerve palsy
16
Q
You do a TKA on this patient and surprise! He gets a peronal nerve palsy. What are some risk factors? How do you treat?
A
-
Prognosis
- most resovle in 3 months
-
Risk Factors
- use of epidural anesthesia;
- previous spinal surgery (double crush);
- valgus knee deformity
- flexion contracture more than 20 deg
- abarent retractors
- pre-op neuropathy
-
Immediate
- take of dressing
- flex the knee
- throrough documentation of physical exam
-
Post-op
- AFO
- PT for ROM
- EMG with-in one month
-
At 3 months
- Repeat EMG for improvement
- Decompression with neuroloysis
- 4 cm proximal
- adherence to fibular head
- 7-15 cm distal to fibular head
17
Q
Amount of antibiotics to put in antibiotic cement
A
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- Need to keep under 2g/40g of cement to preserve mechanical function
- Safe loading dose
- Vanco - 10.5g
- Gent - 12.5g (although some report lower - 2g)
- Masri recommends 3.6g tobra and 1g vanc per 40 mg
- Powder is poured into liquid cement, vacum is not used - keeps porosity high to help with elution of cement
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18
Q
What’s the most important factor in post-op TKA ROM?
A
Pre-op ROM
19
Q
Pros and Cons of a CR knee
A
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- Most common, relies on native PCL
- Bone conserving
- More consistent joint line preservation
- Proprioceptive feedback
- Disadvantages<!--StartFragment-->
- Loss of PCL will lead to instability and failure
- Tight PCL will cause tightness in flexion and cause lift-off of component
- Excessive resection will cause failure from repetitive subluxation
- Instability, pain, buckling
-
Harder to balance
- Avoid in varus > 10, valgus > 15
-
PCL Rupture
- Trauma
- Osteolysis
-
Paradoxical movement - due to loss of ACL
- Tibia slides forward under the femur instead of posteriorly
Modern implants move center of rotation more posterior
- Tibia slides forward under the femur instead of posteriorly
- Loss of PCL will lead to instability and failure
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20
Q
Pros and cons of anteriorly stabilized knee
A
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- Anterior lip prevents femor from rolling forward
- PE is highly congruent, there is no cam
- Advantage
- Bone conserving
- Easier balancing
- Operative versatility
- Regulated kinematics
- Disadvantage
- Increased PE surface
- Minimal rollback
- Flexion gap laxity = instability and pain - requires treatment to assess this
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21
Q
Indications, pros and cons of a PS knee
A
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- Outcomes are the same for PS and CR knee
-
Indications
- Previous patellectomy - weak extensor mechanism can lead to anterior dislocation
- Inflammatory arthritis - leads to PCL rupture<!--EndFragment-->
- varus >10
- valgus >15
-
Advantages
- Easier balancing
- No sliding
- better flexion
-
Disadvantages
-
Cam jump - if flexion gap is loose, knee will hyperextend, rotate and jump over post and dislocate
- Reduce with sedation, 90 deg of flexion and anterior drawer maneuver
- Avoid in knees with >130 flexion
- Ultimately needs to be revised to address loose flexion gap
- Overreleased poplitues with saw blade
- Overrelease anterior MCL
- Anterior translation femoral component
-
Patella Clunk
- Scar tissue superior to patella gets cause in box
- Flexion - Ex at 45 deg
- Treatment - arthroscopic or mini open debridement
-
PE Wear from tibial post
- Causes aseptic loosening
- If need if hyperextended will cause impingement anteriorly and increase wear rate
- Flexed femoral component, excess tibial slope, anterior translation
-
Additional bone removed
- For post
- Large flexion gap
- Due to PCL removable
- Need to take more distal femur to account for this
-
Cam jump - if flexion gap is loose, knee will hyperextend, rotate and jump over post and dislocate
- **Beware joint line elevation with patella baja** Max 8mm **
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22
Q
Indications for the use of this prosthesis?
A
- LCL/MCL attenuation or deficiency
- Flexion gap laxity
- *Can be used more in revision TKA, but consider at times for primary
- ie; severe valgus knee
the patient depicted had instability following CR knee and PCL rupture
23
Q
Indications for the following prosthesis
A
Constrained hinge with rotating platform
- Tibia rotates with-in yoke to allow rotation during gait
- Without rotation there was a high loosening rate
- Intramedullary stem for high rotational loads
-
Indications
- Global ligament deficiency
- Hyperextension instability (polio or tumor resection)
- Knee resection for tumor
- Complete MCL (controversial)
24
Q
Why was this prosthesis choosen?
A
Tumour Prosthesis
- tumour
- significant bone loss
25
Q
You do this procedure on a healthy 65 yo male. What are all the complications?
A
-
Femoral Notching
- Jig is placed too low on the femur
- Lowers load to failure (fracture)
- In bending the fracture extend from the notch creating an oblique fracture
- Peroneal Nerve Palsy
-
PCL deficiency (in a CR knee)
- Will become loose in flexion, knee will feel unstable and femur will start to slide forward
- Will get anterior knee pain
- Treat with revision to PC or CCK
- Lateral Retinacular Release
- Patella Fracture
-
Intra-operative MCL injury
- Primary repair with 6 weeks NWB with full ROM (if young)
- Recommended treatment is to covert to highly constrained prosthesis
- Arthrofibrosis
-
Post-op Flexion Contracture
- The most important factor of post-op range of motion is pre-op ROM
- In a well balanced knee the gastroc is the cause of the flexion contracture
-
Severe extra-articular femoral deformity
- Can do a combined osteotomy with TKA with long stem that goes past the osteotomy site
-
Osteolysis
- Usually around 8-10 years
- Gradual increase in effusion with mild warmth but no erythema
- Normal lab results and aspiration
- Most common place is the posterior femoral condyle
26
Q
What is usually causing a flexion contracture post-op TKA
A
gastroc
27
Q
When do you usually see osteolysis in TKA and where do you get it?
A
8-10 years
posterior femoral condyle
28
Q
You do the following procedure. They come back at 6 weeks and a stiff knee. How do you approach this?
A
-
Functional ROM
- 90 degrees needed to go down stairs
- 95 to get up from a chair
-
Factors to assess
- Boney resection
- patella baja/elevation of joint line
- tibial slope (not enought)
- posterior osteophytes
- patient factors
-
Radiography
- Assess joint line based on fibula and patella
- Assess alignment of implants
- presence of osteophytes
-
Treatment
- depends on the surgeon, some will take them back if not to 90 by 6 weeks, can be done up to a year
-
Manipulation
- usually at 6 weeks
- Later manipulation as high rate of fracture
-
Scope
- release adhesions, cement/loose bodies
- Arthrotomy
- poly exchange, patellar exchange, posterior release, tuberosity transfer, quads snip
- Not highly recommended, often fails with recurrent pain and stiffness
-
Revision TKA
- tibial tuberosity osteotomy, V-Y plasty
- address tibial slope, patellar height
29
Q
TKA. Patient can no longer extend their knee. How do you approach this?
A
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- Can also occur with lowering of the joint line
-
Overview
- patellar tendon rupture is a rare and devastating complication after TKA with an incidence reported ranging from 0.17% to 2.5%
- Quadriceps tendon rupture extremely rare ~1%.
- Higher risk with infection, multiple surgeries, hinged prosthesis
-
Patellar Fracture
- Thickness <12mm
- Lateral retinacular release (osteonecrosis)
- Due to transection of superior genicular artery
- Osteonecrosis
- Theoretical risk with removal of fat pad, lateral release, quads turndown
- Blood supply comes from the medial to lateral part of the knee
- Can also be caused by maltracking or direct trauma
-
Quads or patellar tendon rupture
- Overall very poor outcome
-
Treatment
- Can treat conservatively if the component is solid and there is no extensor lag
- Quads
- Drill holes if no patella resurfacing
- Suture anchors if there is less bone stalk
- Patellar
- Primary repair with drill holes or suture anchor does not do well
- Component revision if there is enough bone, component resection if not
- Allograft or autograft if there is significant extensor lag
- Fresh frozen is the prefered choice
- Use a detensioning wire (or mersiline tape) for 3 months
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30
Q
Considerations when deciding whether to resurface the patella
A
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- High clinical variability in practice
- **Complications **
- patellar fracture
- malailignment
-
Consequences
- Anterior knee pain with higher revision rate
- 50% re-operation rates and higher complication rates with no patellar resurfacing - at about 5 years outcomes become the same
- Earlier designs had a high failure rate, newer designs have longer survivorship
-
Technique
- Indicaitons to resurface
- maliagnmnet
- minimal wear
- inflammatory disease
- If you’re not resurfacing use a more anatomic design
- Patellar cut
- Use the caliper before and after
- Under resection leads to pain and a tight compartment
- Over resection leads to fracture - max thinness is 12mm
- Medial-superior placement is ideal
- Helps to restore Q angle with fewer tracking complications
- Lateral Release
- complications
- fracture
- component dislocation
- wear
- infection
- Indicaitons to resurface
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31
Q
Diagnosis? Causes? Treatment considerations in TKA?
A
Patella Baja
-
Introduction
- A condition manifested by a shortened patellar tendon
- Leads to limited flexion due to patellar impingement on the tibia in extremes of flexion
-
Causes
- proximal tibial osteotomy
- tibial tubercle shift or transfer
- proximal tibia previous trauma
-
Presentation
- mechanical block to full flexion
-
Management
- Operative with TKA
-
lowering joint line
- distal femoral augmentation and cutting off more proximal tibia
- avoid bone cuts that raise the joint line (raising the joint line will effectively increase the patella baja deformity)
-
elevating patella
- use small patellar component and place superiorly
- trim bone or polyethylene to reduce impingement
-
lowering joint line
- one option in severe deformity is to cut the patella but not to resurface it (this will reduce patellar impingement allowing for more knee flexion)
- Operative with TKA
32
Q
This patient comes into your clinic with a painful knee. What is your approach and general priniciples?
A
RULE OUT INFECTION!!!!!!!!!
- take a complete history around the pain, duration, time pain free, instability, PMHx, smoking
- assess for knee stability, contractures, neurological issues, vascular issues
- previous inctions
- patellar tracking
- Get all previous OR notes
- ESR, CRP, possible aspiration
- Bone scan - fracture, infection
- Imaging - AP, lateral WB views, full length standing
- compare to previous, assess for further lysis
- assess opposite knee
- Look at lysis around each component
- component alignment, shift
- posterior sag tibia = PCL
- full alignment of knee
-
Goals of revison surgery
- extraction of components with minimal bone loss and destruction
- restoration of bone deficiencies
- restoration of joint line
- balance knee ligaments
- stable revision implants
- address patellar malalignment
- soft tissue coverage
-
Exposure
- Use most lateral incision with multiple incisions
- Try to leave skin bridge 6cm if you can’t use old incision
- Release all adhesions and scar tissue
- do not pull off the patellar tendon
- If the patella cannot be everted safely
-
Quads snip - snip across the quads
- No need to protect WB
- 45 deg angle to arthrotomy
-
Patellar turndown - V-Y
- Associated with weakness
- Protect WB with extension brace for 6 weeks
-
Tubercle ostotomy
- Less weakness but can’t do if there is patellar baha
- 2cm wide, 1cm thick, 6 cm long
- start 1cm medial to tubercle with an osillating saw
- finish laterally with an osteotome
- stemed revision must bipass osteotomy
- WBAT with ROMAT
-
Quads snip - snip across the quads
- Prothesis Extraction
- Do with as little damage as possible
- Contact rep for specific implant removal
- ostotomes, punchs, slap hammer, clamps, saw, burr
- Take poly out
- Free femur with saw and osteotome
- don’t lever
- remove with punch or slaphammer
- Similar technique with the tibia
- may need to cut the stem
- osteotomy for exposure
- Patella
- can leave, or cut the pegs off and then drill them out
- Clear cement, if you are re-cementing you can leave the cement
- Bone Loss
-
Cause
- __abrasion, infection, osetolysis, extraction
- load sharing to the diaphysis (stem)
- stem is cement often, unless you have such sever bone loss you need to go up to the diaphysis (not like a hip)
- cavity defect filling
- cement
- for cavitary defect is < 1 cm
- structural bone grafts
- includes metal augments, or modular endoprosthetic devices
- indicated for segmental defect > 1cm
- cement
-
Cause
- Appropriate implants
- Tibia first, establish joint line
- use contralateral films
- 2cm above fibular head
-
hinged
- no ligamentous support
- multiply revised
- hyperextension seen in polio
- tumor, infection
- charcot (relative)
-
CCK/stem (constrained condylar knee)
- MCL/LCL laxity
- flexion gap
- CR to PS or CCK
- Tibia first, establish joint line
- Soft tissue
- Medial gastroc is the most reliable
- Do not delay closure, should be done at the same time as revision
33
Q
Complications associated with Revision TKA?
A
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-
Pain
- pain scores less favorable than primary TKR
- activity related pain can be expected for 6 months
- Stiffness
-
Neurovascular problems
- peroneal nerve subject to injury with correction of valgus and flexion deformity
- Infection
-
Skin necrosis
- prior scars should be incorporated into skin incision whenever possible
- bloody supply to anterior knee is medially based, so lateral skin edge is more hypoxic
- if multiple previous incisions, use most lateral skin incision
- can use wound care, skin grafting, or muscle flap coverage (gastroc) for full thickness defects
-
Extensor mechanism disruption
- can use extensor mechanism allograft using achilles tendon
- Semi-T graft can be used to help augment
- Can use this intra-op if you loose the tendon
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34
Q
Indicaitons, contraindications and optimal position
A
KNEE ARTHRODESIS
-
Indications
- painful ankylosis after infection or trauma
- neuropathic arthropathy
- tumor resection
- salvage for failed TKA (most common)
- loss of extensor mechanism
-
Contraindications
- absolute
- active infection
- relative
- bilateral knee arthrodesis
- contralateral leg amputation
- significant bone loss
- ipsilateral hip or ankle DJD
- absolute
-
Optimal Position
- 5-8° valgus
- 0-10° of external rotation (match other leg)
- 0-15° of flexion
- some limb shortening advantageous for patient self-care
35
Q
Options for fixation for the following? Complications?
A
-
Fixation
-
Intramedullary rod fixation
- can be one long antegrade device or a two part device connected at the knee
- patella can be left alone or incorporated into arthrodesis
-
External fixation
- must allow compression of arthrodesis site
- done with unilateral external fixation, Ilizarov, or Taylor Spatial Frame
-
Plate fixation
- can be done alone in combination with intramedullary nailing
-
Intramedullary rod fixation
-
Complications
- Nonunion
- Infection
- Low back pain
- Ipsilateral hip degenerative changes
- Contralateral knee degenerative changes
- Fracture
- supracondylar femur or proximal tibial metaphysis fractures
36
Q
Indications and contraindications; Advantages and disadvantages
A
-
Indications
- patients with advanced arthritis and good proximal femoral bone stock
- three types of patients for whom hip resurfacing is indicated (Amstutz, et al)
- patients with proximal femoral deformity making total hip arthroplasty difficult
- patients with high risk of sepsis due to prior infection or immunosuppression
- patients with a neuromuscular diagnosis
-
Contraindications
-
absolute
- bone stock deficiency of the femoral head or neck (e.g., cystic degeneration of the femoral head)
- >75% femoral head
- abnormal acetabular anatomy (small)
- Associated with acetabular loosening
- bone stock deficiency of the femoral head or neck (e.g., cystic degeneration of the femoral head)
-
relative
- coxa vara
- increased risk for neck fractures
- significant leg length discrepencies (resurfacing does not allow for leg length corrections)
- female gender (controversial)
-
absolute
-
Advantages
- preservation of femoral bone stock
- improved restoration of hip biomechanics with lower risk of limb length discrepancy
- lower dislocation rate
- rapid recovery
- revision is easier than an intremedullary THA
- better stability compared to standard small head (22- to 32-mm) THA
- ability to engage in high demand activities
-
Disadvantages
- lack of modularity with inability to adjust length or correct offset
- requires larger exposure than conventional THA
37
Q
Outcomes of hip resurfacing
A
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- variable outcome findings in the literature (79% to 98% success rate)
- better results
- young
- larger males
- excellent bone stock treated
- osteoarthritis better than for dysplasia or osteonecrosis
- some case series have shown survival comparable to conventional THA, while others have reported higher rates of early revision
- some products have been removed from the market due to early failure
- more recent prospective trials have shown few differences between resurfacing and THA
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38
Q
Patient comes in one year following hip resurfacing for OA. Differential for associated complications.
A
- RULE OUT INFECTION
-
Periprosthetic femoral neck fracture
- incidence of 0% to 4% (more common than in THA)
- frequent cause for revision in acute post-operative period (<20 weeks)
- mechanism thought to be related to osteonecrosis
-
risk factors:
- notching of the femoral neck
- osteoporotic bone
- large areas of pre-existing osteonecrosis
- femoral neck impingement (from malaligned acetabular component)
- female sex
- varus positioning of femoral component
- presents as groin pain
- treatment
- convert to a THA
-
Implant loosening (aseptic)
- early loosening of the cemented femoral resurfacing component
-
Heterotopic ossification
- higher incidence of heterotopic ossification (from wider exposure)
-
Elevated metal ion levels in blood and urine from metal debris (unknown significance)
- Metallosis
- pseudotumour
- ALVAL (Aseptic Lymphocytic Vasculitis Associated Lesions)
- Can see this on biopsy
- Treatment is to replace with a THA metal on poly
39
Q
What are three ways to assess the rotation of your femoral component?
A
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- **anteroposterior axis **
- defined as a line running from the center of the trochlear groove to the top of the intercondylar notch
- a line perpendicular to this defines the neutral rotational axis
- **transepicondylar axis **
- defined as a line running from the medial and lateral epicondyles
- the epicondylar axis is parallel to the tibial surface
- A posterior femoral cut parallel to the epicondylar axis will create the appropriate rectangular flexion gap
- **posterior condylar axis **
- defined as a line running across the tips of the two posterior condyles
- this line is in ~ 3 degrees of internal rotation from the transepicondylar axis, the femoral prosthesis should be externally rotated 3 degrees from this axis to produce a rectangular flexion gap
- if the lateral femoral condyle is hypoplastic, use of the posterior condylar axis may lead to internal rotation of the femoral component
<!--EndFragment-->
40
Q
Deformities associated with CAM (clinical/anatomical - not radiographic)
A
decreased head-to-neck ratio
aspherical femoral head
decreased femoral offset
femoral neck retroversion
41
Q
Deformities associated with Pincer (clinical/anatomical - not radiographic)
A
anterosuperior acetabular rim overhang
acetabular retroversion
acetabular protrusio
coxa profunda (deep socket)
42
Q
Radiological features of FAI
A
-
Technique
- Hips in 15 deg IR with beam centered between symphysis and ASIS
- Assess symmetry of obturator, tear drops; symphysis should be 1-2 cm from the coccyx
-
Findings
- Overall
- Tonnis grade - OA
- Joint space < 2mm is a poor prognostic factor
- Shenton’s line
- Acetabulum
- CEA > 40, Tonnis angle < 0
- Version; cross over sign, ischial spine sign
- Retroversion index > 33-50% are significant
- Assess protrusio, coxa profunda
- Posterior wall sign
- Femoral side
- Assess coxa vara
- Sphericity and contour of femoral head - ‘pistol grip deformity’
- Overall
-
Dunn view
- Alpha angle >50 (cam)
-
Cross-table lateral
- Head neck off-set >8mm (cam)
-
false profile view
- to assess anterior coverage of the femoral head
- standing position at an angle of 65° between the pelvis and the film
43
Q
What is the tonnis grade for arthritis
A
- Grade 0 - no signs of OA
- Grade 1 - sclerosis with minimal joint space narrowing
- Grade 2 - small cysts in head or acetabulum with joint space narrowing
- Grade 3 - large cysts in the head with obliteration of joint space and severe head deformation
45
Q
Diagnosis? Treatment Options?
A
DDH
-
Conservative
- first line of treatment
- NSAIDS, activity modification
-
arthroscopic osteochondroplasty of acetabular rim and/or femoral head reshaping
- reserved for mild to moderate lesions without posterior involvement of the femoral head or neck
- Can be done via scope or surgical dislocation (trochanteric slide)
- Risk of osteotomy non-union
-
periacetabular osteotomy +/- a femoral osteotomy
-
Salter osteotomy (Ganz/Bernese)
- Most commonly used, allows medialization of the hip joint that reduces hip reaction forces
- Lateral rotatation, anterior rotation, with medialization of femoral head
- indications
- Pain or progressive limp
- Adequate ROM
- >90 deg flexion
- >30 deg abduction
- concentrically reduces hip/congruent joint
- good joint space (tonnis < 2)
- advantages
- provides hyaline cartilage coverage
- posterior column remains intact and patients can weight bear
- Does not change pelvic shape in women of weight bearing age
- preserves hip abductors
-
salvage pelvic osteotomy (chiari, shelf)
- Not used as frequently due to improvements in THA
- indications
- unreduced hip
- incongruous joint with obliterated joint space
- Can confirm with an abduction view whether the hip is reducible
- major goal of procedure
- cover femoral head with fibrocartilage (NOT articular cartilage)
- Will often need a graft to cover the head anteriorly
- Drawback of shelf is that you are not medializing the joint
-
Salter osteotomy (Ganz/Bernese)
-
Femoral Osteotomy
- Often needed when you don’t get enough coverage of the head
- Need to use flouro to decide where optimal position is
- Don’t close the canal too much because it makes future THA difficult
-
Arthrodesis or resection arthroplasty
- Options but not good ones for DDH
- Resection arthroplasty might be better for patients with neuromuscular conditions
-
total hip arthroplasty (THA)
-
indications
- treatment of last resort for those with severe arthritis
- preferred treatment for older patients (>50) and those with advanced structural changes
- in a patient with bilateral hip dysplasia, there are significant technical challenges that need to be addressed to ensure a successful total hip arthroplasty.
-
indications
47
Q
Technique of a PAO
A
- Smith-peterson
-
4 cuts
- anterior ischium below the acetabulum
- superior pubic ramus
- supra-acetabular ilium
- posterior column (joining cut number one)
-
Re-approximate (for DDH)
- Tilt laterally and anteriorly
- Avoid excessive extension and retroversion
- Rotate inwardly
- Medialize
- Tilt laterally and anteriorly
- Fix with k-wires, assess ROM and position with flouro
- Secrure with 4.5 cannulated screws
- Arthrotomy
- Assess head-neck junction and perform osteochondroplasty as necessary
49
Q
Technique for a femoral osteotomy
A
-
PFO can be altered as per what you need
- DDH - varus +/- ER
- SCFE (Southwick) - flexion, abduction, IR
- Femoral neck nonunion - southwick
- Place a k-wire at the level of the ostotomy site
- Place a k-wire where the blade should go
- This will depend on the angle of the plate
- Can also assess whether you will need flex or ex at this time
- This should be at least 1.5cm away from k-wire1
- 3rd kwire or chisel is used to determine the length of the blade
- Use a chisel to make the blade cut along wire number 2
- Mark your version with a k-wire
- Osteotomize the femur at Kwire 1
- Remove a wedge if you need to
- Remove the chisel
- Place the balde, watch this under flouro
- Secure the blade to the proximal fragment
- Secure the plate to the distal fragement
- Check the position on flouro
-
Post-op
- Start abduction at 6 weeks
- TTWB until 8-12 weeks
- Plate may be removed at 1-2 years
-
Complications are technical
- Blade protrusion into joint
- Fragmentation of distal fragment
- Nonunion
-
Outcome
- 25% conversion to THA at 15 years
- Improved outcomes with less OA
51
Q
Approach to residual LCP
A
-
Residual deformity
- Coxa magna
- Asphericity
- Coxa plana
- Short neck
- Acetabulum remodels and becomes dysplastic
-
Usually requires
- Osteochondroplasty, neck lengthening, distal trochanteric transfer
-
Approaches
-
Anterior approach combined with lateral for PFO
- Can be extended up to do an acetabular osteotomy if they have instability
- Surgical dislocation to do everything
-
Anterior approach combined with lateral for PFO
- If they need both POA and PFO you can stage it or do it at the same time
53
Q
Portals for hip arthroscopy
A
-
Anterolateral portal
-
function
- primary viewing portal
- anterolateral hip joint access
-
location and technique
- located 2 cm anterior and 2cm superior to anterosuperior border of greater trochanter
- typically established first under flouroscopic guidance
-
function
-
Posterolateral portal
-
function
- posterior hip joint access
-
location and technique
- located 2cm posterior to the tip of the greater trochanter
-
function
-
Anterior portal
-
function
- anterior hip joint access
-
location and technique
- located at intersection between
- superior ridge of greater trochanter
- ASIS
- flexion and internal rotation of hip loosens capsule and assists scope insertion
- located at intersection between
-
function
54
Q
Complications of hip arthroscopy
A
-
Direct injuries
- can occur from scope or cannula placement
- most commonly reported complication
- chondral injuries
-
Neurovascular injury
- traction related
-
pudendal nerve injury
- most common neurovascular complication
- due to traction post in groin for traction
- neuropraxia or compression injury
-
peroneal nerve injury
- traction neuropraxia
-
may prevent traction injuries with
- intermittent release of traction
- adequate anesthesia
-
anterolateral portal
- risks superior gluteal nerve
-
posterolateral portal
- risks sciatic nerve
- increased risk with external rotation of hip
- risks sciatic nerve
-
anterior portal
- risks lateral femoral cutaneous nerve injury
- risks femoral neurovascular bundle
- risks ascending branch of lateral femoral circumflex artery
56
Q
Risk factors
A
AVN
- Alcoholism
-
steroids (either endogenous or exogenous)
- High the dose the higher the risk
- dysbaric disorders (decompression sickness, “the bends”)
- marrow-replacing diseases (e.g. Gaucher’s disease)
- sickle cell disease
-
hypercoagulable states
- May explain idiopathic disease
- SLE
- Inflammatory Bowel Disease
- transplant patient
- virus (CMV, hepatitis, HIV, rubella, rubeola, varicella)
- protease inhibitors (type of HIV medication)
-
AVN associated with trauma
- due to injury of femoral head blood supply (medial femoral circumflex)
- AVN rates of specific injuries
- femoral head fracture: 75-100%
- basicervical fracture: 50%
- cervicotrochanteric fracture: 25%
- hip dislocation: 2-40% (2-10% if reduced within 6 hours of injury)
- intertrochanteric fracture: rare
57
Q
Radiographic work-up for AVN
A
- Think to get imaging of both hips, 50% of the time is a bilateral disease
-
Radiographs
- AP hip
- Double line sign associated with crescent sign
- Present in 80% of cases
- frog-lateral of the hip - more sensitive
- classification systems based largely on radiographic findings (see below)
- Size of lesion - % head on AP X % head on lateral
- Small - < 15%
- Medium - 15-30%
- Large - > 30%
- AP hip
-
MRI - Gold standard
- highest sensitivity and specificity
- T1: dark
- T2: bright (marrow edema)
- Will have evidence of high signal from edema as well as low signal changes
- Extent of femoral head involvement
-
Kerboul Angle
- Combine necrotic angles on saggital and coronal
- >200 associated with poorer outcomes
58
Q
Diagnosis? How do you know? Prognosis?
A
Transient Osteoporosis of the Hip
- Classic picture is low signal on T1 and high signal on T2 with no evidence of low signal in T2
- All the way threw the head, neck and trochanteric region
- If there are risk factors or concerns of AVN you can do serial progression, TOH will resolve
59
Q
Ficat classification
A
-
stage 0:
- plain film: normal
- MRI: normal
- clinical symptoms: nil
-
stage I:
- plain film: normal or minor osteopaenia
- MRI: edema
- clinical symptoms: pain typically in the groin
-
stage II:
- plain film: mixed osteopenia &/or sclerosis &/or subchondral cysts, without any subchondral lucency (crescent sign: see below)
- MRI: geographic defect
- clinical symptoms: pain and stiffness
-
stage III:
- plain film: crescent sign & eventual cortical collapse
- MRI: same as plain film
- clinical symptoms: pain and stiffness+/- radiation to knee and limp
-
stage IV:
- plain film: end stage with evidence of secondary degenerative change
- MRI: same as plain film
- clinical symptoms: pain and limp
60
Q
Options for treatment
A
AVN
-
Prognosis
- 80% will collapse
-
Bisphosphonates
- indicated for precollapse AVN (Ficat stages 0-II)
- trials have shown that alendronate prevents femoral head collapse in osteonecrosis with subchondral lucency
- Shock-wave, hyperbaric has been tried, but hasn’t been showed to work and there is no evidence behind it
- Tantalum rod is an old procedure that was thought to provide support and perhaps revascularization but the outcomes have been shown to be poor
-
Core decompression with bone grafting
-
indications
- for early AVN (FICAT 1, 2), before subchondral collapse occurs
- Small lesions (<15%)
- Reversible cause
- Now will just do multiple tracks with a smaller drill bit
- **Just don’t drill below the less troch region
- Not very good results
-
indications
-
Rotational osteotomy
-
indications
- only for small lesions (<50%) in which the lesion can be rotated away from a weight bearing surface
- Beaule paper
- <45 deg
- Kerboul < 200
- off steroids
-
technique
- typically performed through intertrochanteric region
- Japan does a trans-trochanteric that has not become common in NA
- Need to be careful because can make conversion to THA more difficult
-
indications
-
vascularized free-fibula transfer
-
indications
- pre-collapse in patients young and over 40
- Moderate to large lesion
- collapsed AVN in young patient
- Reversible cause
-
technique
- fibular strut is placed under subchondral bone to help prevent collapse or tamp up small areas of collapse
- complications - are related to donor site morbidity
- sensory deficit
- motor weakness
- FHL contracture
- tibial stress fracture from side graft is taken
-
indications
-
total hip replacement
-
indications
- femoral head collapse
- acetabular DJD
- Advanced collapse in younger patients
-
Technique
- Remember that the bone quality is poor - be gentle with acetabular reaming
- Evaluate the femur for previous surgery - core decompression, osteotomy
- Use a large head, use a lateral approach
- Consider ceramic in younger patients
-
Outcomes
- in young patients with osteonecrosis there is a higher rate of linear wear of the polyethylene liner and a higher rate of osteolysis than when compared to older patients who have THA for osteoarthritis
- Should be using uncemented components so they can in-grow
-
indications
-
total hip resurfacing
-
indications
- in advanced DJD with small, isolated focus of AVN
- contraindicated in underlying disease process or chronic steroid use causing AVN (poor bone quality) and renal disease (metal ions from metal-on-metal implant)
-
indications
-
hip arthrodesis
-
indications
- only consider in the very young patient in a labor intensive occupation
-
indications
64
Q
Two classifications for DDH when considering THA?
A
-
Crowe
- I
- Less than 10% Proximal
- Less than 50% lateral
- II
- 10-15% proximal
- 50-75% lateral
- III
- 15-20% proximal
- 75-100% lateral
- IV
- Greater than 20%
- Greater than 100%
- I
-
Hardofilakidis
-
Dysplasia (Type A)
- Femoral head within acetabulum despite some subluxation. Segmental deficiency of the superior wall. Inadequate true acetabulum depth.
-
Low dislocation (Type B)
- Femoral head creates a false acetabulum superior to the true acetabulum. There is complete absence of the superior wall. Inadequate depth of the true acetabulum.
-
High dislocation (Type C)
- Femoral head is completely uncovered by the true acetabulum and has migrated superiorly and posteriorly. There is a complete deficiency of the acetabulum and excessive anteversion of the true acetabulum.
-
Dysplasia (Type A)
65
Q
What are you consderations for THA
A
- Acetabulum
- smaller cup, superior migration, false acetabulum
- loss of anterior/superior and lateral coverage
- Augment with screw fixation
- Augment with implant augments
- Small cup mean a small femoral head to accommodate sufficient poly
- Offset-bore components are available that change the position of the head in the poly to reduce risk of instability
-
Femur
- Previous surgeries
- Loss of canal
- Posterior GT
- GT osteotomy or ETO
- May need to shorten
- 2-4 cm is max without shortening
- Soft tissue changes associated with superior migration
- Abductors become transverse
- Psoas and capsule hypertrophy
- Adductor, rectus and hamstring shortening
- Previous surgeries
66
Q
Technical approach for each crowe classification
A
-
Technique for I
-
Acetabulum
- can usually use the native acetabulum
- size less of an issue
- Just consider degree of bone loss
-
Femur - no need to shorten
- Try to go cementless because these patients are young
- Minimal deformity - metaphyseal fitting proximally coated stem
- Larger deformity - small, DDH stem with minimal flare
- Diaphyseal fitting, long coating
- Allows correction of version
-
Acetabulum
-
Technique for II/III and Hardofilikas B
-
Acetabulum
- 1) Leave the cup superior (high hip center)
- Means you will have a very small cup
- May need less shortening
- increased stress with early failure
- 2) Medialize the cup (acetabuloplasty) at native hip center
- Reduces joint reaction forces
- 3) Augment with bone graft which is available from the femoral head
- Poor results have been published when > 30% of head is uncovered requiring graft/augment (this is when you would consider leaving the cup more superior)
- 1) Leave the cup superior (high hip center)
-
Femur
- Will need a diaphyesal fitting stem with modular components to assess verion
- fully porous coated
- fluted?
- May need to be shortened
- >2-4 cm
- GT osteotomy with sequential femoral resection
- Canal that is left is poor quality
- Need to use a small DDH cemented stem
- Subtroch osteotomy is better but harder to do - do this from a posterior approach
- make subtroch osteotomy and leave hip in pseudoacetab
- prepare the acetab
- shorten your femur as necessary, release the head and soft tissues
- size your stem
- reduce secure the stem with k-wires/allograft as necessary
- Risk of nonunion
- Will need a diaphyesal fitting stem with modular components to assess verion
-
Acetabulum
-
Technique IV
- Put in the native acetabulum
- Extra-small cup
- The bone will be soft, don’t over ream
- Do the last reamer on reverse
- Posterior approach for femoral shortening osteotomy via GT or subtroch osteotomy
- Put in the native acetabulum
68
Q
What is true about the biomechanics and pathology of this patient?
A
Hip Arthrodesis
-
Pathomechanics
- reduces efficiency of gait by ~50%
- increases pelvic rotation of contralateral hip
- increases stress at adjacent joints
-
Biochemistry
- increases oxygen consumption
- requires 30% more energy expenditure for ambulation
-
Prognosis
- provides pain relief and reasonable clinical results in most patients
- success may be limited by adjacent joint degeneration in 60% of patients
- lumbar spine, ipsilateral knee or contralateral hip may be affected
- low back pain and arthritic ipsilateral knee pain are the most common symptoms
- may start within 25 years of hip arthrodesis
*
69
Q
This is a 16yo male with a combined pelvis and femoral neck fracture. He developed infection post-op. After I&D, 6 weeks IV abx and 6 weeks PO abx, he has resolving ESR/CRP with an abx holiday. What is your plan now? Explain your technical approach.
A
Hip arthrodesis
-
goals
- achieve apposition of arthrodesis surfaces, obtain rigid internal fixation and promote early mobilization
-
plan for future THA
- preserve the abductors
- preserve bone stalk; address missing bone stalk
-
optimal position
-
20-35° of flexion
- Appropriate flexion for sitting, reduce lumbar strain
- Too much can exaccerbate LLD
-
0°-5° adduction
- avoid abduction as it creates pelvic obliquity and increased back pain
- Too much adduction can make sexual activity and toileting difficult in women
-
5-10° external rotation
- Facilitates putting on shoes and foot care
-
Leg length
- < 2cm difference is acceptable
- Can use abduction to correct 2cm (cannot abduct further than that)
- Do not abduct > 6 deg
- >4 cm stage the procedure and do a second lengthening procedure
- < 2cm difference is acceptable
-
20-35° of flexion
-
Approach
-
lateral approach with trochanteric osteotomy is preferred
- important to preserve the abductor complex (used to strip the abductors off the pelvis, now elevate them)
- avoid injury to the superior gluteal nerve
-
anterior approach to hip is also popular
- Less risk to the abductors
- supine on the operative table makes positioning hip easier
- Screw augments the plate - lag screw done first, the plate onto crest up near SI
-
lateral approach with trochanteric osteotomy is preferred
- Address bone deficiet
-
Instrumentation
- cobra plating
- anterior plating
- double plating
- trochanteric approach
- better with excessive bone loss, provides more support
- 2 stage - first prepare the joint, second fix the GT back down
- improves fusion rates
70
Q
This patient comes back to you at 25yo with low back pain. What is you assessment/approach now?
A
-
Prognosis
- provides pain relief and reasonable clinical results in most patients
- success may be limited by adjacent joint degeneration in 60% of patients
- lumbar spine, ipsilateral knee or contralateral hip may be affected
- low back pain and arthritic ipsilateral knee pain are the most common symptoms
- may start within 25 years of hip arthrodesis
-
Conservative treatment
- Consider other causes of low back pain
- Do a full hx and neurological exam
- ask about progression of the pain and any attempt at conservative treatment
- ask about pain in other joints
- try to prolong take-down
-
Conversion of fusion to THA
-
Indications - pain in adjacent joints
- severely debilitating back pain (most common - 70%)
- severe ipsilateral knee pain with instability
- severe contralateral hip pain
- Relative:
- LLD > 3 cm
- previous nonunion of arthrodesis
-
Contraindications
- unable to cope with large procedure (relative)
- active infection - stage procedure)
-
Indications - pain in adjacent joints
-
Pre-op
-
Full History
- Pain
- Indications and age at initial procedure
- Spontaneous vs surgical
- Complications following the procedure
-
Exam
- Incisions, palpate abductors
- Assess hip position, LLD
- Lumbar spine, contralateral hip, ipsilateral knee
- Full NV exam
-
Rule out infection
- ESR, CRP
- Neutrophil count intra-op
- If concerns, take down with prostalac with staged procedure
-
Imaging
- AP/lateral pelvis, full length standing (LLD), judet views
- Assess for position of the plate and bone stalk
- CT for bone, and alignment
- MRI or ECG to access abductors
-
Full History
-
Outcomes
- clinical outcome is dependent on abductor complex function
- Good outcome patient can expect
- Improved back/joint pain
- Increased mobility
- Resolved leg length discrepancy
- the presence of hip abductor complex weakness or dysfunction
- requires prolonged rehabilitation (2years)
- severe lurching gait may develop
71
Q
Technique and considerations to perform THA on these patients
A
Hip Arthrodesis conversion to THA
-
Goals
- (1) identify and preserve the hip abductor muscles
- (2) accurately identify the hip rotation center of the acetabulum
- (3) perform concentric reaming of the acetabular bone bed to achieve medialization and sizing of the component
- (4) avoid placement of the acetabular cup in an excessively cephalic position
- (5) optimize leg length equalization
- (6) restore ideal femoral offset to avoid impingement and instability
-
Supine on a radiolucent table
- supine easier assessment of acetabulum
- will need flouro guidence
-
Approach
-
GT osteotomy (more common)
- Fix with circlage wires or claw plate for weaker bone
-
Posteroateral
- Avoid issues with nonunion of osteotomy site
-
GT osteotomy (more common)
-
Take down osteotomy
- Junction between the ilium and femoral neck is the osteotomy site
- Use flouro
- Anterior acetabular rim and sciatic notch can also be used
- Transverse acetabular ligament if present
- Have allograft or augments available in case of poor bone stalk or deficiency
-
Acetabulum
- Define the acetabulum
- Be cognicent of the position of the other hip
- Flexion and adduction of the other hip might cause pelvic obliquity and you may antevert the cup
- Cup
- Porous coated, multi-hole cup or porous metal (TM)
- Large cup to allow for a larger poly/head
-
Femur
- Want more offset to improve abductor function
- Large head (>36)
- Increase ROM, decrease instability
- Proximal stem usually ok
- Have a revision stem on hand if required
-
Post-op
- PWB for 6-8 weeks
- Will require can for excessive period of time
- Hip precautions or abduction splint
- Because poor soft tissue/abductors
- At risk of dislocation
- Complications
-
Intra-op
- pelvic discontinuity
- greater trochanteric fracture
- femoral perforation
- calcar fracture
-
Post-operative
- trochanteric osteotomy nonunion
- infection
- dislocation
- nerve palsy
- HO
-
Intra-op
-
Outcomes
- clinical outcome is dependent on abductor complex function
- Good outcome patient can expect
- Improved back/joint pain
- Increased mobility
- Resolved leg length discrepancy
- the presence of hip abductor complex weakness or dysfunction
- requires prolonged rehabilitation (2years)
- severe lurching gait may develop
73
Q
Hip Biomechanics and joint reaction force
A
- Center of rotation is the center of the femoral head
-
Forces threw the hip
- 2.5 X in single leg stance
- 3 X with walking
- 6 X with running
- Cane - takes weight away from the hip
-
Decrease joint reaction force - increase in ratio of A/B (shift center of rotation medially)
- moving the acetabular component as far medial, inferior, and anterior
-
shifting body weight over affected hip
- this results in Trendelenburg gait
- reduces abductor pull
- increasing offset of femoral component
- long stem prosthesis
- lateralization of greater trochanter
-
varus neck-shaft angulation
- increases shear across joint
-
cane in contralateral hand
- reduces abductor muscle pull and decreases the moment arm between the center of gravity and the femoral head
-
carrying load in ipsilateral hand
- produces additional downward moment on same side of rotational point
-
increase joint reaction force
-
valgus neck-shaft angulation
- decreases shear across joint
- Lateralize cup/liner
- decreased offset
-
valgus neck-shaft angulation
85
Q
Su classfication of periprosthetic fractures
A
-
Type I
- Fracture is proximal to the femoral component
-
Type II
- Fracture originates at the proximal aspect of the femoral component and extends proximally
-
Type III
- Any part of the fracture line is distal to the upper edge of anterior flange of the femoral component
104
Q
Paprosky acetabulum
A
Type I - Minimal deformity, intact rim
Type IIA - Superior bone lysis with intact superior rim
Type IIB - Absent superior rim, superolateral migration
Type IIC - Localized destruction of medial wall
Type IIIA - Bone loss from 10am-2pm around rim, superolateral cup migration
Type IIIB - Bone loss from 9am-5pm around rim, superomedial cup migration
105
Q
Paprosky Femur
A
-
Components
- ischial bone loss
- tear drop lysis
- femoral head center migration
- kohlers line (ilioischial line)
-
Type I Minimal metaphyseal bone loss
- proximal fitting wedge taper stem
-
Type II Extensive metaphyseal bone loss with intact diaphysis
- fully porous coated diaphyseal stem
-
Type IIIa Extensive metadiaphyseal bone loss, minimum of 4 cm of intact cortical bone in the diaphysis
- fully porous coated dephyseal stem
-
Type IIIb Extensive metadiaphyseal bone loss, less than 4 cm of intact cortical bone in the diaphysis
- fully porous coated modular tapered stem with derotational spines
-
Type IV Extensive metadiaphyseal bone loss and a nonsupportive diaphysis
-
APC
- step cut into native femur reinforced with circlage wires to help creeping subsitution
- risk of disease transmission, benefit is bone in young patients
- impaction grafting
- clean canal of cement and fibrous tissue, reinforce with mesh
- morsalized allograft then cement in revision stem
- proximal femoral replacement
- instability, loosening, can’t reattach soft tissues
-
APC
106
Q
Options for acetabulum reconstruction in revision THA
A
- Paprosky 1/2
- porous metal, hemispherical, multi-hole revision cup
- can use metal augmets to bolster the cup if there is significant bone loss
- allograft is no longer recommended
- Paprosk 2c/3a/3b
- porous metal cup with metal augments
- antiprotrusio cage with cemented liner
- if you think the acetabulum won’t heal (cancer, pagets) then you don’t need to put a cup in because you’ll never get ingrowth
- does not have good long term outcomes
- advantages of cementing liner
- can cement liner in proper position
- can use antibiotic cement
- Distraction cup
- jumbo cup is used to distract the disontinuity, need to be careful in poor quality bone
- only really good results from paprosky
- cup-cage construct
- cage has a phalange that goes into the ishium and then secured with screws onto the ilium
- custom triphlange cup
- made to bridge the defect
- porous titanium, HA coated
- phalange for ischium, ilium and pubis
- expensive, stiff, question of whether it can incorperate
