Recon Flashcards
What is the most common complication associated with total hip arthroplasty in patients with Paget’s bone disease?
Increased blood loss. pre-operative bisphosphonates may help to damped the disease process and help control blood loss.
What is the most common complication associated with Paget’s bone disease and total knees?
Malalignment.
Which area of the tibial plateau is convex and which is concave?
lateral tibial plateau is convex. Medial tibial plateau is concave.
What is “rollback” in regards to knee kinematics?
Distal femur has a larger radius of curvature laterally alone with a convex lateral tibial plateau so more rollback occurs when the knee goes into extension. This is what causes the distal femur to pivot about the medial axis of the knee.
What are the recommended ranges for acetabular and femoral component positions?
30-50 degrees abduction 5-25 degrees of anteversion 10-15 degrees of femoral ante version.
What is the most common way to sterilize polyethylene implants?
Gamma irradiation in an inert gas.
Recommendation for antirheumatic drug administration before and after total joint arthroplasty?
DMARDS (Methotrexate and hydroxychloroquine) CONTINUE Biologic agents (Etanercept and Infliximab) stop these medications prior to surgery and schedule surgery at the end of the dosing cycle. Resume medications at minimum of 14 days after surgery.
What is kinematic alignment in total knee arthroplasty?
Component placement to recreate a patient’s natural anatomy.
For varus knee for example will have varus tibial cut and vlagus femoral cut
Equivalent if not better outcomes.
What kind of prosthesis design is recommended for a patient with a neuromuscular disease and genu recurvatum.
Rotating hinge design
What techinical errors contribute to stress fractures after uni-compartmental arthroplasty?
excessive guide pin number.
suboptimal placement for the tibial resection guide.
undersizing of the tibial component.
What are the AAOS recommendations for Management of Osteoarthritis of the Knee?
CPM
Cyrotherapy
Rehabilitiation on the day of TKA
Tourniquet Use with regard to postoperative short-term function
Strong against
Moderate against
Strong for
Limited
What is an anterior stabilized total knee prosthesis?
Highly conformed polyethylene component with a large anterior lip, which prevents anterior translation of the femur on the tibia.
This increases the contaact area of the implant.
Used for PCL deficient knees.
Is it recommended patients with osteopetrosis undergo joint arthroplasty?
Yes for end stage arthritis.
THA: use cannulated reamers under fluoro, short stemmed implants, uncemented. For Cup use small sharp reamers, irrigate, and use multiple screws.
TKA: Consider navigation
What are the indications for use of a constrained nonhinges prosthesis?
severe varus/algus deformity with MCL/LCL incompetency
Severe bone loss.
Inability to balance flexion-extension gaps due to severe flexion contractures
Persistent varus-valgus laxity despite adequate releases
Neuropathic arthropathy
Post-polio sequelae
What is the max amount of acetabular coverage is acceptable and has not been associated with increased rates of aseptic loosening?
30%
Which femoral condyle remians stationary and which moves with flexion?
What happens to the tibia?
Medial femoral condyle stationary 0-120 of flexion.
Lateral femoral condyle and contact area moves posterior on the tibia from 0-120 degrees of flexion.
Both condyles participate in femoral rollback beyond 120 degrees.
Tibia internally rotates with knee flexion and tibia EXternally roates with EXtension
What are the four quadrants and their dangers for screw placement for acetabular cups?
When does driving reation times return to preoperative reaction time in nearly all patients after THA?
4-6 weeks.
What is the optimum position for a hip arthrodesis?
5-10 external rotation
5 adduction
20-35 hip flexion
What is the optimal pore size for cementless porous implants to allow for optimal bony ingrowth?
500-400 microns
What sized wear particles are implicated in osteolysis?
Less than 1 micron (submicron)
How do you determine volumetric wear?
V=3.14xradius squaredxlinear head wear
What linear wear rates have been associated with osteolysis?
Linear wear rates greater than .1mm/yr
non-cross linked UHMWPE wear is .1-.2 mm/yr
What are the pros and cons of highly cross linked UHMPE?
Pro: generates smaller particles and is more resistant to wear.
Con: has reduced mechanical properties compared to conventional non-highly cross-linked poly.
What factors increase wear in THA?
thickness < 6mm
malalignment of components
patients < 50 yo
men
higher activity level
What is the difference between wear rates of highly cross linked UHMWPE with a femoral head that is 22mm vs 46mm?
None
Femoral head size has not been shown to change wear rates between 22 and 46mm in highly cross-linked UHMWPE
What is the wear rate of ceramic on ceramic?
Ceramic on poly?
2.5 to 5 micrometers per year
ranges from 0-150 micrometers per year.
What is the wear rate of metal on metal total hips?
What type of inflammatory cell is thought to be involved in the biological response to metal-on-metal particulate debris?
2.5-5 micrometers
lymphocytes
What cell produces Osteoprotegrin?
What cell produces RANKL?
What is PTH role in the process?
What cell is RANK bound to?
RANK binding to RANKL leads to what?
What osteolytic cytokines are released by macrophages?
TNF-alpha: increase of this leads to increasing RANK.
Osteoclast activating factor
Oxide radicals
Hydrogen peroxide
Acid phosphatase
Interleukins (IL-1, IL-6)
Prostaglandins
Variables involved in catastrophic wear or failure of polyethylene
PE thickness
articular surface design
kinematics
PE sterilization
PE machining
How thick should the thinnes portion of the polyethelene be to avoid failure?
8mm
Keep in mind that PE insert width is usually defined as the maximal thickness of the PE insert and the metal tray, not just the PE.
What have newer total knee designs done to compensate for lack of rollback with more congruent articular designs?
Move the point of contact where the femoral condyle rests more posterior and have a steeper slope to aid with flexion.
Flatter polyethelene has more femoral rollback but have less contact surface area leading to higher stress loads and greater chance for failure.
What is the consequence of sterilizing polyethelyne in an oxygen rich environment?
PE becomes oxidized.
Leads to early failure by subsurface delamination, pitting, and fatigue cracking.
While sterilization in an oxygen depleted environment improves resistanct to adhesive and abrasive wear it decreases ductility and fatigue resistance.
Aside from sterilization and packaging how should PE be fabricated?
Direct compression molding of PE. 50% lower wear rates than machined products. Will look highly polished. Downside is it is slow and expensive.
No machining as the shear forces can lead to subsurface delamination and fatigue cracking. Shows a white band 1-2mm below the articular surface.
What are the rates of primary joint replacement infection TKA vs THA
Revision TKA vs THA
1-2% TKA and .3-1.3% THA
5-6% TKA and 3-5% THA
True or false inflammatory arthropathies lead to higher risk of infection in joint arthroplasty?
True
Increased with rheumatoid, psoriasis, and ankylosis spondylitis.
How soon before surgery should you stop DMARDs?
How long does it take to create a biofilm on prosthesis?
biofilm created by all bacteria forms on implants within four weeks.
Infection that has persisted longer than 4 weeks must be explanted.
Describe the major and minor criteria of the MSIS 2018 criteria for prosthetic joint infections.
CRP peaks when, returns to normal when, and what is the normal value for acute and chronic periods?
Peaks: 2-3 days after surgery
Returns to normal at 21 days(3 weeks)
Acute < 6 weeks from surgery <100mg/L
Chronic > 6 weeks from surgery <10mg/L or 1mg/dL
ESR peaks when, returns to normal when, and what is the normal value for acute and chronic periods?
Peaks: 5-7 days after surgery
Returns to normal 90 days (3 months)
No consensus on value in the actue period.
> 6 weeks from surgery should be < 30mm/hr
Serum interleukin-6 normal vlaue, peak, and how long after surgery before it returns to normal?
Peaks 8-12 hours after surgery
Returns to normal 48-72 hrs after surgery.
Shows very high correlation with periprosthetic joint infection but less commonly followed.
False positives with RA, MS, AIDS, and Pagets.
What are the lowest cell counts and differentials suggestive of infection in the following?
TKA
Acute (less than 6 weeks) TKA
THA
MoM hips
Hip abx spacers
TKA >1100 WBC and >64% PMN
> 27800 WBC
> 3000 WBC and 80% PMN
> 4350 and 85% PMN
WBC >1166 and PMN >64%
What is indicative of infection on an intraoperative frozen section?
>5 PMNs/hpf in 5 hpfs
Sensitivity 85% and specificity 90-95%
When can a polyethylene exchange with component retention be performed?
Ideally <48-72 hrs from symptom onset but can be as long as 3 weeks after surgery (acute infections)
How mach Vancomycin and Tobramycin should be added to a 40g bag of cement for a spacer?
For local cement?
3g of Vancomycin and 3.6g of tobramyin or Gentamycin.
Abx must be heat stable.
Use extra liquid monomer 1.5-2 ampuole monomer per 1 bag of cement.
Is gender a risk factor for osteoarthritis of the hip?
Yes females > males
What is aggrecanase-1 (ADAMTS-4)?
a matrix metalloprotease responsible for cartilage matrix digestion.
What are the differences between the following listed in the image in aging and osteoarthritis?
What genes are potentially linked to OA?
Non-mendilian inheritance for hip arthrits.
Vitamin D receptor
Estrogen receptor 1
Inflammatory cytokines: IL-1(leads to catabolic effect), IL-4, Matrilin-3, BMP2, and BMP-5.
How do you test for a hip flexion contracture?
Thomas test
Patient supine fully flex one hip
If contralateral hip lifts off table there is likely a fixed flexion deformity
What is a FADIR test and what is it used for?
Flex hip to 90 degrees then adduct and internally rotate
Pain in the hip or groin is suggestive of a possible labral tear or FAI.
What is a Patrick’s Test for hips?
Anoterh name for FABER
Flex to 90, ABduct and externally rotate.
Positive if patient has hip or back pain or limited ROM
Can suggest intra-articular hip lesions, ilipsoas pain, and SI disease if posteriorly located pain.
What is Ober’s test
Used to test for tight or painful iliotibial band (ITB)
patient in lateral position with affected side up.
With hip in slight extension abduct leg and then allow it to drop into adduction.
If unable to adduct then tight ITB.
Normal ROM for a hip?
Flexion 120-135 deg
Extension 20-30 deg
Abduction 40-50 deg
Adduction 20-30 deg
Internal rotation 30 deg
External rotation 50 deg
How do you determine the risk of femoral head collapse with osteonecrosis?
Modified Kerboul combined necrotic angle.
Direct cause risk factors for osteonecrosis?
irradiation
trauma
hematologic diseases (leukemia, lymphoma)
dysbaric disorders (decompression sickness, “the bends”)- Caisson disease
Marrow-replacing diseases (e.g. Gaucher’s disease)
Sickle cell disease
What are indirect cause risk factors for osteonecrosis?
alcoholism
hypercoagulable states
steroids
SLE
transplant patient
virus (CMV, hepatitis, HIV, rubell, rubeola, varicella
Protease inhibitors (type of HIV medication)
Idiopathic.
What is T2 focal brightness of the femoral head predictive off?
Predictive of worsening pain and future progression of disease.
When and what medication can be used for AVN of the femoral head?
Can be used for precollapse (Ficat stages 0-II)
Bisphosphonates
Some studies have shown benefit in preventing collapse others have not.
One trial with alendronate showed that it prevented collapes in femoral heads with subchondral lucency
What complications are seen with vascularized free fibula transfers?
Donor site morbidity that includes:
Sensory deficit
Motor weakness
FHL contracture
Tibial stress fracture
For patients with osteonecrosis of the femoral head undergoing total hip arthroplasty what complication is more common than standard THA?
Higher rates of femoral canal perforation.
Rates ranging from 4.9-18.2%
This is because of medullary widening adjacent to areas of dense sclerosis.
How do you obtain a Modified Dunn view and what is it used for?
Hip flexed 45 deg and abd 20 degrees.
Aim bean 2.5cm above pubic symphysis
Better demonstrates relationship of femoral head with acetabulum
Useful for confirming femoroacetabular impingement (alpha angle)
How do you obtain a false profile and what is it used for?
Patient standing
Pelvis externaly rotated 65 degrees
Beam aimed at femoral head
Provides true lateral projection of femoral head/neck and oblique view of acetabulum.
Demonstrates anterior acetabular coverage of femoral head. Useful for etermining anterior center-edge angle.
Describe the Crowe Classification?
For Adult dysplasia of the hip.
How do you find the lateral center-edge angle of wiberg and what is a normal range?
Ap x-ray. Angle between vertical line through femoral head and line along lateral acetabulum.
Normal 25-40 deg
< 20 deg is hip dysplasia
>40 deg is overcoverage.
How do you determine the anlge of tonnis?
Whats the normal range?
What is an abnormal value indicative of?
On AP image angle between line through inferior sourcil parallel tointer-teardrop line + line from inferior to lateral sourcil
0-10 degrees
Hip instability > 10 degrees
Pincer-type FAI < 0 degrees
How do you determine an alpha angle of the hip?
Lateral x-ray (modified Dunn)
Normal is <42 degrees
Cam lesion >50-55 degrees.
How do you find the anterior center-edge angle also known as the angle of lequesne?
False profile x-ray.
> 20 degrees is normal.
How much of a cement mantle do you want for cemented acetabular cups?
2-3mm
What is the Dorr classification used for in arthroplasty?
To determine femur morphology and aid in decision to use cemented vs cementless stem.
Ratio of inner canal diameter 10cm distal to lesser trochanter to level at lesser trochanter.
Type A = <.5 No cement indicated
Type B = .5-.75 no cement indicated
Type C = > .75 cement indicated
What is the most common pathoanatomy factor in adult hip dysplasia?
Acetabular retroversion
Dysplasia is attributable to 1/3rd of all cases of hip osteoarthritis.
A patient with hip dysplasia will have what kind of increased ROM before osteoarthritis sets in?
Increased internal rotation due to increased femoral anteversion.
How do you determine head-neck offset ration of the hip?
Will it be decreased or increased in adult hip dysplasia?
Normal is > .15
It will be decreased in hip dysplasia.
Assessed on lateral view
What is the increased risk of nerve plasies and dislocation after THA for hip dysplasia?
10 times increased incidence of sciatic nerve palsy (5-15%)
Lengthening greater than 4cm can lead to sciatic nerve plasy that will present clinically as a foot drop.
Increased risk of hip dislocation 5-10%
What are the indications for a periacetabular osteotomy +/- a femoral osteotomy in adult hip dysplasia?
Indications: symptomatic dysplasia in an adolescent or adult with a concentrically reduced hip and congruous joint with good joint space.
Advantages: Provides hyaline cartilage coverage, posterior column remains intact and patients can weight bear, preserves external rotators, delays need for arthroplasty.
Describe a Chiari osteotomy for adult hip dysplasia?
Salvage Osteotomy
Cut made above acetabulum to sciatic notch so that you cna shift ilium lateral beyond edge of acetabulum.
Shelf osteotomy is another salvage option. Increase the weight bearing surface by placing extra-articular buttress of bone over the subluxed femoral head. Femoral head is covered with fibrocartilage not articular cartilage.
Where is the center of gravity of the human body?
Just anterior to S2
Is the coeffecient of friction of a human hip for or less than that of a metal on PE total hip arthroplasty?
Less, human joint .002 to .04
Metal on PE is .05 to .15
What actions decrease joint reaction forces within the hip?
What increased joint reactive forces?
Acetabular side: moving acetabular component medial, inferior, and anterior
Femoral side: Increasing offset of femoral component, long stem prosthesis, lateralization of greater trochanter(by using increased offset neck/prosthesis)
Patients gate: Shifting body weight over affected hip, cane in contralateral hand, carrying load in ipsilateral hand.
valgus neck shaft angle, but decreases shear across joint.
What are some complications unique to press fit femoral stems?
Intraoperative fractures- usually due to underreaming. More likely in press-fit through lateral approach.
Loosening- do not use press-fit in irradiated bone
Junctional corrosion- seen in modular components, so can occur in cemented as well.
What is a complication more common in cemented stems than press-fit stems?
Stem breakage. The stems are small than press-fit stems and unable to tolerate as much cantilever bending.
What type of hypersensitivty reaction occurs with metal on metal total hips?
What cell mediates the process?
What other cell is more prevalent and involved in the process?
Type IV delayed type hypersensitivity
Mediated by T-cells. The metal ions sensitize and activate T-cells
Most participating cells are macrophages. They are activated by T-cells that secrete cytokines. The activated macrophages have increased ability to present Class II MHC and IL-2 which increases T-cell activation.
What increases the risk of squeaking with ceramic on ceramic THA?
edge loading
impingement and acetabular malposition
third-body wear
loss of fluid film lubrication
thin, flexible titanium stem.
What is the advantage of vacuum mixing cement in arthroplasty?
vacuum mixing reduces the porosity of the cement which reduces stress points in the cement that could be points of failure.
Cemet fixation of a femoral stem is optomized by?
Limited porosity of cement
cement mantle > 2mm
Stiff femoral stem- flexible stem places stress on the cement mantle
Stem centralization- varus or valgus positioning increases stress on cmeent mantle
Smooth femoral stem- sharp edges produce sites of stress concentration
What is the Barrack and Harris grading system used for?
Radiographic analysis of cemented femoral stem.
True or false cemented femoral stems have higher success in the revision setting?
False
Cemented femoral stems have lower success in the revision setting.
Biologic fixation of press fit implants is optimized by what:
pore size?
porosity?
gaps?
micromotion?
contact?
Pore size 50-300um
Porosity of 40-50%- more porosity than this may lead to shearing of metal
gaps <50um- defined as space between bone and prosthesis
Micromotion <150um- more than this can lead to fibrous ingrowth
Maximal contact with cortical bone
True or false all girt blasted femoral stems or extensively coated?
True
fixation strength is lest with grit blasted surfaces necessitating greater area of surface coating.
start up pain a year after a THA is a sign of what?
Femoral stem lossening will have start up pain and thigh pain.
Acetabular loosening will have groin/buttock pain classically.
A higher Youngs modulus =?
Higher modulus of elasticity = stiffer material
Titanium 115 GPa
Stianless steel is higher.
What are normal serum colbalt and chromium levles?
cobalt < .9ng/mL
chromium < .3ng/mL
How much irradiation is needed for PE to cross-link?
What is the ideal level of crystallinity of PE?
What crystallinity is associated with increased PE failure?
high dose 5-15 Mrad
50%
Greater than 70%
How much does a hip arhtrodesis reduce the efficiency of gait by?
What increase in energy expenditure is there?
50%
30% more energy expenditure.
What are contraindications to primary hip arthrodesis?
Active infection
Limb length discrepancy > 2.0 cm
bilateral hip arthritis or adjacent joint degenerative changes (lumbar spine, contralateral hip, or ipsilateral knee).
Severe osteoporosis
Contralateral THA. Increased failure in that THA by 40% with a contralateral hip arthrodesis.
What must be done before converting a hip arthrodesis to a THA?
preoperative EMG to assess the status of the gluteus medius
a constrained acetabular component is required if the abductor complex is nonfunctional.
The presence of hip abductor complex weakness or dysfunction requires prolonged rehabilitation and a severe lurching gait may develop.
Lateral approach with troch osteotomy or anterio approach.
What is an absolute contraindication to hip resurfacing?
Relative contraindications?
Bone stock deficiency of the femoral head or neck (cystic degeneration)
Coxa vara-increased risk for neck fractures
Significant leg length discrepancies-cannot correct leg length with resurfacing
Pregnancy-metal ions can cross the placenta
Renal failure-metal ions are excreted through the kidney
What is the most common complication after hip resurfacing?
Periprosthetic femoral neck fracture 0-4%
most common within first 3 years and cause for revision in acute post-operative period (<20 weeks)
Risk factors: femoral neck notching, osteoporotic bone, large areas of AVN, femoral neck impingement, femalse sex, and varus positioning.
Treatment is conversion to THA.
What must be done if a patient has an elevated WBC with a metal on metal arthroplasty?
Manual count as the WBC count is likely falsely elevated.
What is standard magnification of a x-ray used for templating total joints?
20%
Most templates account for this.
Best to have a magnification marker.
external rotation of the leg on a AP radiograph of the hip will lead to what false findings when templating?
Should be taken with 10-15 degrees of internal rotation.
External rotation will lead to falsely decreased offset
Valgus appearing femoral neck
Falsely decreased femoral canal diameter.
Does a skirt increase or decrease the head neck ratio?
Skirts decrease the head-neck ratio.
What is the advantage and disadvantage of a lateralized liner?
Increses offset which increases soft-tissue tension.
Has been show to increase the risk of acetabular componenet loosening.
The lateral translation increases joint reactive forces and polyethylene wear.
What is the recommended combined component anteversion in THA?
Around 37 degrees
5-25 for acetabular cup
10-15 for femoral stem.
List all of the ways that offset can be increased to improve hip stability?
Increasing length of femoral neck
decreasing neck-shaft angle
Medializing the femoral neck while increasing femoral neck length.
Trochanteric advancement
Alteration of the acetabular liner (lateralized liner)
Increasing offset leads to?
Decreasing offset may lead to?
Decreased impingement, decreased joint reaction force, and increasing soft tissue tension without increasing leg length.
Instability, abductor weakness, and gluteus medius lurch.
What are the three factors that controll proper soft tissue function to think about when considering THA?
Central nerovus system- such as stroke or parkinsons
Peripheral nervous system- such as peripheral neuropathy or radiculopathy
Locoal soft tissue integrity- such as trauma, irradiation, infection or malignancy
What changes with regards to screw placement in “high hip” or elevated hip center?
The sturctures in the anterosuperior and anterioinferior quadrants can be found in the posterosuperior quadrant.
What can be caused by leaving the anterior rim of the acetabular component proud above the native acetabulum?
Iliopsoas tendon impingement.
Can be evaluated by cross-table laterals and anesthetic injection of the iliopsoas tendon sheath.
Has preoperative physical therapy been shown to improve post-operative outcomes in THA?
No
Driving recommendations after THA?
3-4 weeks after right THA
Less than 3-4 weeks after a left THA
Reaction time returns to preoperative levels at 4-6 weeks.
What are the internervous planes for a smith-peterson approach?
Superficial: sartorius (femoral N.) and tensor fasciae latae (superior gluteal N.)
Deep: Rectus femoris (femoral N.) and Gluteus Medius (superior gluteal N.)
What are the dangers found during an anterior hip approach for THA?
LFCN- passes under inguinal ligament. Most commonly seen when incising fascia between the sartorius and the tensor fascia latae. Course is variable can be medial or lateral to ASIS.
Femoral nerve- Should remain protected as long as you stay lateral to sartorius muscle.
Ascending brach of lateral femoral circumflex artery- found proximally in the internervous plane between the tensor fascia latae and sartorius. Should be ligated.
Describe a hardinge or Tranglutear approach for THA
No true internervous plane.
Split TFL to find gluteal medius tendon.
Splits gluteus medius distal to innervation(superior gluteal nerve) and vastus lateralis (femoral nerve) distally.
Dangers: Do not exten incision more than 3-5 cm above greater trochanter to prevent injury to superior gluteal nerve (leading to trendelenburg gait). Anterior retractor needs to be right against bone to avoid iatrogenic injury to femoral nerve.
What is a Watson-Jones approach for THA?
anterolateral approach.
Make incision 2.5cm posterior and distal to ASIS
Interval between TFL and gluteus medius
Have to detach abductor mechanism by torch osteotomy vs partial reflection.
Most common problem is compression neuropraxia caused by medial retraction.
What is the greatest risk factor for prosthetic hip dislocation?
What are other risk factors for dislocation?
Prior hip surgery
Females sex, Age > 70-80 yrs, posterior surgical approach, malpositioned components, spastic or neuromuscular disease, drug or alcohol abuse, decreased femoral offset, and decreased femoral head to neck ratio.
What is a change in the peg-neck angle on follow-up indicative of after a hip resurfacing?
Chnage in peg neck angle is concerning for aseptic loosening.
Can also represent femoral head necrosis/collapse or femoral neck fracture.
Decreased distance from tip of peg to lateral femoral cortex can also represent femoral head necrosis/collapse.
Narrowing of the femoral neck after 3 years or >10% narrowing can represent impingement.
What is the most common location for a post-op fracture after a THA?
At femoral stem tip.
Risk factors for acetabular fractures during THA?
Underreaming > 2mm
elliptical modular cups
osteoporosis
cementless acetabular components
dysplasia
radiation
When, where, and with what implants to post-operative femur fractures occur?
Early postoperative fractures: cementless prosthesis tend to fracture in the first six months. Likely caused by stress risers during reaming and broaching. Wedge-fit tapered designs cause proximal fractures. Cylindrical fully porous-coated stems tend to cause a distal split in the femoral shaft.
Late postoperative fractures: Cemented prosthesis tend to fracture later (5 years out). More likely to fracture around the tip of the prosthesis or distal to it.
How should Vancouver B3 periprosthetic fractures be treated generally?
Young patients with component revision and proximal femoral allograft.
Elderly, low demant patients with proximal femoral replacement.
PCL resection during a TKA results in what change in flexion or extension gaps?
Results in a relative increase in the flexion gap compared to the extension gap.
It simulates excessive posterior femur resection.
What is the rate of sciatic nerve palsy in THA?
Which division is more commonly affected?
0-3% reported
80% of the time peroneal division
What are the risk factors for motor nerve palsies after THA?
Prognosis?
DDH, Revision surgery, Female gender, limb lengthening, posttraumatic arthritis, surgeon self-rated procedure as difficult.
Only 35-30% recover full strength after a complete palsy.
Obesity is not listed as a risk factor
What can provide the sensation of a long leg after THA but not truly have a LLD?
Weak abductors may provide the sensation of a long leg.
Usually spontaneously resolves within 3-6 months.
How do you measure true limb length discrepancies?
How do you measure apparent limb length?
Measured from ASIS to medial malleolus
Apparent measured from medial malleolus to navel. Apparent limb lengths due to soft tissue contractures that lead to pelvic obliquity.
What is the most common treatment for LLD after THA?
Wait 6 months to allow adequate relation of muscles. If LLD persisting then a shoe-lift is adequate in the majority of cases.
Concern with revision THA for LLD leading to dislocation.
Name a often underrecongnized cause of recurrent groin pain after total hip replacement? Leads to subtle findings that include slight limp and tenderness in the groin. Pain is reproduced by resisted seated hip felxion and striaght leg raises.
Iliopsoas impingement.
Can be caused by retained cement, malpositioned acetabular component, LLD, and excessive screw lengths.
Diagnosed by cortisone injection into iliopsoas tendon sheath.
Almost always requries operative intervention for symptoms to resolve. Iliopsoas tenotomy if normal radiographs and or CT. Acetabular component revision if malpositioning are concern for impingement.
What is the most common organsim cultured from aspiration in both septic olecranon and prepatellar bursitis?
Staph Aureus.
Treatment is 1 week immobilization, compressive wrap, and NSAIDs. +/- aspiration.
Rare indications for bursal resection.
What are the risk factors for iliotibial band friction syndrome?
Training errors: sudden change in training intensity and poor shoe support
Anatomical factors: genu recurvatum or genu varum. LLD. Excessive foot pronation. Weak hip abductors. Tight iliotibial band.
Biomechanical factors: Disparity between quadriceps and hamstring strength. Increased landing forces. Increased angle of knee flexion at heel strike.
What is the impingement zone for iliotibial band friction syndrome?
30 degrees of knee flexion.
What conditions are associated with iliotibial band friction syndrome?
Patellofemoral syndrome
Medial compartment osteoarthritis
Greater trochanteric pain syndrome
Treatment for iliotibial band friction syndrome?
Rest, Ice, NSAIDs (oral and topical), and corticosteroid injections when the previous measures fail.
Physical therapy is critical: Stretching of the iliotibial band, lateral fascia, and gluteal muscles. Deep transverse friction massage. Strengthening hip Abductors. Proprioception exercises to improve neuromuscular coordination.
When non-operative therapy fails and symptoms are chronic can consider elipitical surgicla excision of iliotibial band. As a last resort Z plasty.
True or false once heterotopic ossification is visible on radiographs only surgical excision will eradicate it?
True
How long should you wait after THA before considering surgical excision for HO?
Need to wait 6 months after initial procedure to allow for maturation and formation of capsule.
What is the best predictor of need for transfusion after THA?
What are other risk factors?
low preoperative hemoglobin.
Rheumatoid arthritis, advanced age, longer operative time.
No clear association with BMI, gender, or prophylactic anticoagulation.
What is initial treatment for lateral patellar compression syndrome?
NSAIDs, activity modification, and therapy.
Therapy should emphasize vastus medialis strengthening and closed chain short arc quadriceps exercises.
What are the indications for arthroscopic lateral release?
Objective evidence of lateral tilting. negative tilt on merchant view. See image.
Pain refractory to extensive rehabilitation.
Inability to evert the lateral edge of the patella
idela condidate has no symptoms of instability
Medial patellar glide of less than one quadrant
Lateral patellar glide of less than three quadrants
With regard to patellar realignment surgery:
What is a Maquet procedure?
What is a Elmslie-Trillat procedure?
What is a Fulkerson alignment surgery?
Maquet- tubercle anteriorization. Indicated only for distal pole lesions. Only elevate 1 cm or else risk of skin necrosis.
Elmslie-Trillat- tubercle medialization. Indicated only for instability with lateral translation. Should be avoided if medial patellar facet arthrosis.
Fulkerson alignment surgery- tubercle anteriorization and medialization. For lateral and distal lesions. Patient should have increased Q angle. Contraindicated with superior medial arthrosis. Scope before you perfrom surgery. Cannot be performed in skeletal immaturity.
Describe the Paprosky Classification of Acetabular Bone Loss?
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 atround rim, superolateral cup migration.
Type IIIB: Bone loss from 9am-5pm around rim, superomedial cup migration
Describe the Paprosky Classification of Femoral Bone Loss?
Type I: Minimal metaphyseal bone loss
Type II: Extensive metaphyseal bone loss with intact diaphysis
Type IIIa: Extensive metadiaphyseal bone loss, minimum of 4 cm of intact cortical bone in the diaphysis
Type IIIb: Extensive metadiaphyseal bone loss, less than 4 cm of intact cortical bone in the diaphysis
Type IV: Extensive metadiaphyseal bone loss and a nonsupportive diaphysis
What can be done when you have an irreparable abductor deficiency in a ptaient who you are performing a revision THA?
Gluteus Maximus Transfer
Anterior aspect of gluteus maximus and tensor fascia lata are transferred to the greater trochanter so that the fibers are similarly oriented to the native abductor musculature.
Is a cemented or uncemented stem used in cases of femoral impaction grafting for revision THA?
Smooth tapered stem cemented into allograft.
In a revision setting what femoral stems woud you use for Paprosky II and IIIa defects?
How about IIIb?
Uncemented long stem prosthesis. Can be extensively porous-coated or porous-coated/grit blasted combination. May also use modular tapered stem.
For Paprosky IIIb use a modular fluted tapered stem.
For What Paprosky defects is impaction grafting recommended?
What is the most common complication?
Stem subsidence.
Paprosky IIIB and IV.
For what Paprosky defects would you consider an allograft prosthetic composite?
Paprosky IIIB and IV.
Also can use modular oncology components with these defects.
In general for younger patients with massive femoral defects do APC. For older patients where long term bone preservation is less of a concern use modular oncology components.
True or false the AAOS guidelines state there is strong evidence for use of tramadol in knee osteoarthritis?
True
Weak opiod mu receptor agonist
What recommendations were given by the AAOS for the following use with regards to knee osteoarthritis:
Self-management programs and low impact aerobic activity?
Weight loss for patients with a BMI greater than or equal to 25?
Intra-articular injection with corticosteroid?
Manual therapy (joint mobilization, joint manipulation, myofascial release)?
Acetaminophen?
Strong
Moderate
Inconclusive
Inconclusive
Inconclusive
Inconclusive
Name some treatments the AAOS has given moderate to strong evidence against for knee osteoarthritis.
acupuncture (Strong)
viscolesastic joint injections (Strong)
glucosamine and chondroitin (Strong)
Needle lavage (moderate)
Lateral wedge insoles (moderate)
What are the difference in pain or function with or without patellar resurfacing?
No difference in pain and function.
There is a lower reoperation rate with resurfacing.
What are the AAOS recommendations regarding the following treatments for knee OA:
Arthroscopic debridement or lavage?
Arthroscopic meniscal debridement?
Strong evidence against
Inconclusive evidence.
What is a normal Q angle in males?
Females?
Does it change with flexion?
Measured in extension. Line drawn from the anterior superior iliac spine -> middle of patella -> tibial tuberosity
13 degrees for males
18 degrees for females
8 degrees in flexion
What is the srew home mechanism within the knee?
tibia externally rotates 5 degrees in the last 15 degrees of extension.
this is because the medial tibial plateau articular surface is longer than the lateral tibial plateau.
This locks the knee in full extension to decrease the work performed by the quadriceps while standing.
What are the indications for a cruciate-retaining prosthesis design?
Minimal bone loss
minimal soft tissue laxity
intact PCL
varus deformity < 10 degrees
valgus deformity < 15 degrees
What are the purported advantages of a cruciate retaining TKA?
Advantages: Avoids tibial post-cam impingement/dislocation that can occur. More closely resemebles normal knee kinematics (This is conrtoversial as new poly options that are anterior stabilized or ultra-congruent show no loss of functional results in PCL insufficiency). Improved proprioception with native PCL
Disadvantages:
Tight PCL may cause accelerated polyetheylene wear
Loose or ruptured PCL may lead to flexion instability and subluxation.
What does resection of the PCL in a PS TKA change in the flextion/extension gaps?
Resection of PCL increases the flexion gap in relationship to extension gap becuase it simulates increased posterior femur resection.
This leads to a need for increased distal femur resection to match the flexion and extension gaps.
What are the advantages and disadvantages of posterior stabilized knee designs.
What are indications for a PS TKA design?
previous patellectomy- increased risk of anterioposterior instability
inflammaroty arthritis- increased risk of late PCL rupture
Deficient or absent PCL
What is the theoretic advantage of mobile bearing desing for TKA?
What is a risk with this desing if there is a loose flexion gap?
Increased contact area reduces pressures placed on plyethylene reducing wear?
Bearing spin-out. Tibia rotates behing femur.
What is the purported advantage of highly congruent liners?
What have short and mid-term studies shown about outcomes?
May better create native knee kinematics.
Studies show equivalent outcomes and survivorship in short and mid-term studies.
Medial compartment concavity allows lateral compartment ot translate between flexion and extension. This creates a medial pivot.
When would you use a Constrained Hinged Desing as oppossed to a Constrained Hinged Design?
Globus ligamentous deficiency.
Hyperextension instability- seen in polio or tumor resection.
Massive bone loss in the setting of a neuropathic joint.
Can use a non-hinged design when there is isolated LCL or MCL deficiency of flexion gap laxity.
If a knee has multiple incisions are already present on a knee which incision should be used for a total knee?
Consider using the more lateral as the blood supply comes from the medial side.
What are relative contraindications to a midvastus approach?
ROM < 80 degrees
obese patient
hypertrophic arthritis
Previous HTO
Advantage is though to be from vastus medialis insertion on the quad tendon not being disrupted allowing for accelerated rehab.
What is a known complications with MIS TKA?
When should the procedure be converted to a stnadard parapatellar approach?
High rates of component malposition
If the patellar tendon starts to peel off the tubercle or you cannot fit or properly place the jigs.
Should antibiotic loaded bone cement be used in all TKA procedures?
No it increases the risk of septic loosening.
What are advantages and disadvantages of V-Y turndown?
Advantages:
Allows excellent exposure, allows lengthening of quadriceps tendon, and preserves patellar tendon and tibial tubercle.
Disadvantages:
Extensor lag
May affect quadriceps strength
Knee needs to be immoblilized post-operatively
What are the advantages and disadvantages of tibial tubercle osteotomy for a TKA?
Advantages:
Excelent exposure, avoids extensor lag seen with V-Y turndown. Avoids Quadriceps weakness.
Disadvantages:
Some surgeons will immobilize or limit weight bearing post-operatively
Tibial tubercle avulsion fracture
Non-union
Wound healing problems
What are the steps to a medial release for a varus knee during a TKA?
What occurs if a varus producing tibial osteotomy is done for a deformity > 12 degrees?
The joint line will become oblique
What are specific contraindications to a valgus-producing tibial osteotomy?
Narrow lateral compartment cartilage space with stress radiographs
loss of lateral meniscus
lateral tibial subluxation > 1cm
Medial compartment bone loss > 2-3mm
Varus deformity > 10 degrees
Best results achieved by overcorrection of the anatomical axis to 8-10 degrees of valgus. Lateral closing wedge technique more comon.
If doing a focal dome osteotomy of the tibia which way should the concavity point?
Proximal.
What are complications related to high tibial osteotomy?
Recurrence of deformity- 60% failure rate after three years when patinets are obese are the surgeon fails to overcorrect.
Loss of posterior slope
Patella baja- seen with opening wedge osteotomies
Compartment syndrome
Opening wedge-seen in lateral osteotomies
Malunion/nonunion.
What are the advantages of UKA over a TKA?
Faster rehab
Less blood loss
Less morbidity
Less expensive
Preservation of normal kinematics
Smaller incision.
What are the advantages of UKA over a tibial osteotomy?
Faster rehab
Improved cosmesis
Higher initial success rate
Fewer short-term complications
Lasts longer
Easier to convert to a TKA
What are the contraindications for UKA?
Inflammatory arthritis
ACL deficiency- controversial but some still do medial fixed-bearing.
Fixed varus deformity > 10 degrees
Fixed valgus deformity > 5 degrees
Restricted motion- arc <90 degrees or a flexion contracture of > 5-10 degrees
Previous meniscectomy in other compartment
Younger high activity patients
Overweight (> 82 kg)
Grade IV patellofemoral chondrosis and anterior knee pain.
True of false with a UKA you want to undercorrect the mechanical axis?
True
Undercorrect by 2-3 degrees.
Should correct varus deformity to 1-5 degrees of valgus.
Are current generations of UKAs inlay or outlay style?
Outlay
Replaces entire anterior trochlear surface and minimizes risk of patellar instability
What is the normal antatomy of the knee joint regarding anatomic axis compared to joint line of femur and tibia?
Distal femur is 9 degrees of valgus (anatomic axis compared to joint line)
5-7 degrees valgus of distal femur refers to difference of anatomic axis to mechanical axis.
Proximal tibia is 2-3 degrees of varus (anatomic axis to joint line)
What happens if the joint line is elevated more than 8mm in a TKA?
Mid-flexion instability
Patellofemoral tracking problems
An equivalent to patella baja
What can happen if the joint line is lowered in a TKA?
Lack of full extension
Flexion instability
Increasing the size of the femoral component will have what affect on gap balancing?
Tighter flexion gap.
Increasing/decreasing the size of the femoral component only changes the AP diameter and therefore affects the flexion gap only.
Other than cutting more distal femur what can be done for a TKA that is balanced in flexion but tight in extension?
Release more posterior capsule
what is the most common compliation seen following proximal tibia opening-wedge osteotomy?
Patella baja
What should be done to correct a coronal plane imbalance of 25 degrees for a patient you are seeing who is requesting a TKA?
Have to correct deformities > 20 degrees with an extra-articular femoral osteotomy to acheive proper mechanical alignment.
Cannot be corrected by intra-articular bone cuts and soft-tissue balancing alone.
What is the most common complication of TKAs?
Abnormal patellar tracking.
What techniques during a TKA lead to a increased Q-angle?
Internal rotation of the femoral prosthesis
Medialization of the femoral component
Internal rotation or medialization of the tibial prosthesis
Placing the patellar prosthesis lateral on the patella
What are the three axis that one may use to determine femoral prosthesis rotation for a TKA?
Anteroposterior axis- line perpendicular to a line running from the center of the trochlear groove to the top of the intercondylar notch.
Transepicondylar axis- line running from the medial and lateral epicondyles. A posterior femoral cut parallel to the epicondular axis will create the appropriate rectangular flexion.
Posterior condylar axis- defined as a line running across the tips of the two posterior condyles. The line is in 3 degrees of internal rotation
Where should the tibial component be in relation to the tibial tubercles?
Centered over the medial third.
What should be done if the patella subluxes laterally after placing trail components for a total knee?
deflate tourniquet and recheck before performing a lateral release.
What are some of the most common causes of patella baja?
Proximal tibial osteotomy
Tibial tubercle slide or transfer
Trauma to the proximal tibia
Technical error during primary total knee replacement
ACL reconstruction.
What surgical options are there for patella baja in patients with a TKA?
Place patellar component superior- for mild patella baja
Lower joint line- for moderate patella baja
Transfer tibial tubercle to a cephalad position- for moderate patella baja. Technically challenging. Generally poor outcomes.
Patellectomy- severe patella baja. Last resort.
What are general discharge home criteria after a TKA?
Medically stable.
80-90 AROM
Ambulate 75-100 feet
Stairs.
How many degrees of knee ROM are needed to rise from a chair?
105 degrees of flexion.
Physical therapy after a total knee sould focuse on what kind of exercises?
Closed-chain concentric exercises.
What is the most common intraoperative fracture during TKA?
medial femoral condyle fracture.
What indications and technical considerations should there be for treatment of a periprosthetic femur fracture with a TKA?
Must have an intact/stable prosthesis iwth an open-box design big enought to accomodate the nail.
Fracture must begin at or be superior to the femoral component. No Su Type III fractures.
Make sure to have two distal interlocking screws. Insert the nail deep enough so that there is no impingement with the TKA.
Kee p in mind that the femoral component leads to a more posterior starting point that can lead to hyperextension at the fracture site.
What are risk factors for a periprosthetic patellar fracture?
Assymetric resection of patella
inappropriate thickness of patella
Implant related: Central Single peg implant, Uncemented fixation, metal backing on patella, and inset patellar component.
What is the definition and what are the types of Extension intability?
Extension instability = varus/valgus instability
Types:
Symmetrical- caused by excessive distal femoral resection, causing flexion/extension gap mismatch
Asymmetrical- MORE COMMON. Ligamentous asymmetry caused by failure to correct deformity in the coronal plane.
What is the definition of flexion instability?
Anteroposterior instability
Occurs when the flexion gap exceeds the extension gap
Example is when a posterior stabilized knee jumps the post leading to a dislocation.
Causes and treatment of flexion isntability.
Over resection of posterior femoral condyles -> Treat with posterior augments
Undersizing femoral component -> upsize femoral component
Excessive tibial slope -> decrease slope and consider posterior-stabilized prosthesis
Excessive posterior femoral condyle cuts -> augment posterior condyles of distal femur
Posterior cruciate insufficiency following a cruciate-retaining arthroplasty -> convert to a posterior-stabilized prosthesis.
What is the cause and treatment of mid-flexion instability?
Not entirely understood but associated with modification of the joint line. Involves malrotation when the knee is flexed between 45 and 90 degrees.
Potential contributing factors: Femoral componenet design in sagittal plane. Attenuation of anterior MCL. Overall geometry of the tibiofemoral joint.
TREATMENT: Typically full revision ins required. Goal is restoration of the joint line and equalizing flexion and extension gaps.
What are causes of genu recurvatum in the setting of TKA?
Associated with poliomyelitis, rheumatoid arthritis, or Charcot arthropathy.
Fixed valgus deformity and iliotibial band contracture
Treatment is typically a long-stemmed posterior stabilized or varus/valgus constrained implant.
True or false non-operative treatment in a knee immobilizer for six weeks for partial quadriceps tendon ruptures in patients with a TKA usually results in good motion with a minor extension lag?
True
What is generally held as a cutoff for being able to treat a chondral lesion arthroscopically vs with an arthrotomy?
> 3cm arthrotomy is used.
What percents of unstable juvenile OCD lesions of the knee fixed go on to heal?
85%
What are some causes of patellar prosthesis loosening in TKAs?
Metal-backed patella
Maltracking
Overstuffing
Subclinical infection.
What are risk factors for patellar clunk syndrome?
Pre-op patella baja
Valgus pre-operative alignment
Preoperative fibrosynovial proliferation at quadriceps insertion into the superior pole of the patella. This should be resected at the time of surgery.
Previous knee surgery.
What component factors are involved in the development of patellar clunk?
Small patellar componenet, patellar component palced low on the patella, patellar overrresection and thin patellar button, exposure of cut patellar bone that is not covered by patellar component.
PS design. Smaller femoral component. Femoral component in a flexed position. Increased posterior femoral condylar offset. Femoral component with higher intercondylar box ratio (trochlear groove extended more proximal and anterior). Thick polyethylene insert.
When and how will Patellar clunk present?
Presents on average of 12 months after TKA
Painful, palpable pop or catch as the knee is extended. Occurs between 30-45 degrees.
How should the posterior retractor be placed in TKA to avoid vascular injury?
Stay medial, do not go lateral to PCL. Popliteal artery is a lateral structure at the level of the joint line.
Do not insert the retractor more than 1cm into the posterior soft tissues
Hyperflexion displaces thee artery posteriorly and helps avoid injury.
What albumin and total lymphocyte counts are associated with wound complications in TKA?
Albumin <3.5g/dl
TLC < 1500/ul
What is the blood supply for a medial gastrocnemius rotational flap?
lateral gastrocnemius rotational flap?
medial sural artery
lateral sural artery
Metal hypersensitivity is mediated by what cells?
Mediated by T cells
Type IV delayed-type cell mediated hypersensitivity
What TKA implants should be used for a patient who is found to have metal hypersensitivity?
Hypoallergenic femoral componenet with all-polyethylene tibial component if possible.
How do you diagnose metal hypersensitivity?
Controversial
Diagnosis of exclusion, must rule out infection and aseptic looseninng.
Some argue that patient must have a positive patch test, positive immunohistopahtology, and relief of symptoms upon implant exchange.
What are risk factors for HO in TKA?
Hypertrophic arthrosis
Male Gender
Obesity
Notching of anterior femur
Periosteal injury/stripping off anterior femur
Post-op knee effusion or hematoma
Post-op forced manipulation for restricted motion
What problems may be caused by HO in TKA?
Quadriceps muscle snapping
Patellofemoral tracking difficulties
Patellofemoral instability
What is popliteal snapping syndrome?
Popliteus tendon subluxated anteriorly and posteriorly over a retained lateral femoraly condyle osteophyte.
What is the most common cause of failure in a TKA that was performed three years ago?
Aseptic loosening.
Tibial loosening more common than femoral.
What is the most common cause of failure in a TKA performed 18 months ago?
Septic failure
Most common cause < 2 years.
How long can a bone scan be positive after a TKA?
Up to 2 years after primary TKA.
Negative scan does rule out loosening.
Diffuse uptake can indicate CRPS.
How far should the tibial joint line be above the fibular head?
1.5-2cm above head of fibula.
What size bony defects can be adressed with cement vs needing cones or metpahyseal sleeves?
< 1cm cement is adequate and better than allograft
> 1cm contained defects can use sleeve.
> 1cm uncontained defect need travecular metal cones.
What are the advantages and disadvantages of metaphyseal sleeves?
ADVANTAGES: Encouraging mid to long term data. Efficient and simple. Can be used with cutting guides. Instrumented. Morse taper interface with implant.
DISADVANTAGES: Expensive. Difficult to remove. Specific to each implant manufacturer. Not useful for uncontained defects
What are the advantages and disadvantages of trabecular metal cones?
ADVANTAGES: short-to mid term data encouraging. Variety of shapes/sizes with custom shaping/contouring is possible. Trials/specific instrumentation available. Compatible with several different implant companies. Can be used for uncontained defects.
DISADVANTAGES: Expensive. difficult to remove. Cemented interface to implant. Can be irritant to soft tissues.
Does lumbar laminectomy increase the risk of peroneal nerve palsy in TKA?
Yes, this is thought to occur because of the double crush phenomenon.
What does the alpha-defenisn immunoassay actually test for?
Presence of an intra-articular antimicrobial peptide.
What is the difference in inflammatory cells in metal on metal vs metal on polyethylene in total joints?
Metal on polyethylene = Macrophage induced
Metal on metal = lymphocytes. Type 4 hypersensitivity reaction via T-cells.
What algorithm should be used for work-up of a painful metal on metal arthroplasty?
First rule out infection and fracture.
Second MRI to evaluate for pseudotumor and soft-tissue destruction.
Metal ion levels have little utility in the setting of pain and are only used to monitor a otherwise well functioning joint.
True or false rheumatoid arthritis is and indication for patellar resurfacing?
True
Describe the Harris Hip Score?
In patients with severe arthrits of their hips secondary to AS what is a concern when undergoing THA?
patients have more vertical and anteverted acetabulum that puts them at greater risk for anterior dislocations after THA.
When patients have a kyphotic deformity of their spine that is determined to be from bilateral hip felxion contractures. Can be treated with bilateral THA.
How is DISH defined?
non-marginal syndesmophytes at three successive levels (involving 4 contiguous vertebrae)
Should have preservation of disk height and relative absence of significant degenerative changes: facet-joint ankylosis, SI joint erosion, sclerosis or intraarticular osseous fusion.
also knwon as Forestier disease.
uncommon before 50 years old.
What is the most common location for DISH?
What are risk factors?
thoracic spine (right side more common) > cervical > lumbar
postulated to be due to the protective effect of the pulsatile aorta on the left of the thoracic spine.
symmetrical in the cervical and lumbar spine (syndesmophytes both on left and right of the spine).
RISK FACTORS: gout, hyperlipidemia, diabetes.
What are the associated conditions in the lumbar spine, cervical spine, and fractures with DISH?
LUMBAR: spinal stenosis
CERVICAL: dysphagia and stridor, hoarseness, sleep apnea, difficult intubation, and cervical myelopathy.
FRACTURE: hyperextension injuries even with low energy mechanisms.
What is there increased risk of for THA in patients with DISH?
HO
30-50% for patinets with DISH
<20% for THA in patients without DISH.
If a ceramic head has been fractured what bearing surfaces should be reimplanted at the time of revision?
Another ceramic head should be used as not all of the pieces will be removed and they will sratch a metal head potentially leading to massive third body wear.
True or false use of Jumbo cups can lead to increased risk for recurrent dislocation?
True
May lead to soft-tissue overgrowth around the liner, causing impingement and increasing the risk for recurrent dislocation.
What is the most common cause of early failure of patellofemoral arthroplasty?
Late failure?
patellar instability and maltracking.
The most common cause of late failure is progression of tibiofemoral arthritis?
What has been given a strong recommendation by the AAOS regarding treatment for symptomatic arthritis of the knee?
Self-management programs, strengthening, low-impact aerobic exercises
NSAIDs (oral or topical)
Tramadol
AGAINST acupuncture
AGAINST glucosamine and chondroitin
AGAINST hyaluronic acid
AGAINST arthroscopy with lavage and/or debridement
What is considered antibiotic-loaded bone cement?
Those containing greater than 1.0 g of abx per 40g of Cement.
For Vanc 1.0 gram per 40 grams of cement.
For Tobra 3.6g per 40 grams of cement.
Commercially available antibiotic-loaded bone cement are mor elow dose. They contain either .5 g of tobramycin or gentamycin per 40 g of cement.
Combo of Vanc and Tobra improved the elution of both antibiotics.
What is the most common complications after TKA in patients with ankylosing spondylitis?
Stiffness
Likely due to higher incidence of heterotopic ossification. Incidence was as high as 20% in one study.
What is Ochronosis?
Degenerative arthritis caused by alkaptonuria.
Rare inborn autosomal recessive defect of the hogentisic acid oxidase enzyme system (tyrosine and phenyalanine catabolism).
Excess acid deposits in joints leading to chondrocalcinosislead to dark deposits and arthritis as seen in the figure.
Ochronotic spondylitis occurs furing the fourth decade of life and includes progressive degenerative changes, disc space narowing, and calcification.
Black urine
True or False: Women have better implant survivorship than men for standard non gender specific total knee arthroplasty?
True
As far as gait mechanics go what is the posterior approach for primary joint arthroplasty associated with?
Greater hip adduction moment and a longer step length.
For anterior, anterolateral, and posterior there are similar gait biomechanics with each at less than 3 months and more than 6 months after surgery.
