Total Knee Replacement: Do’s and Don'ts

Ronald S. LaButti, DO, FAOAOLower Extremity and Joint

Reconstruction

Advanced Orthopedics of OklahomaCentral States Division

Tulsa, Oklahoma

Background

ØHome Town- Glocester, RIØProvidence College 1987

Providence, RIØUniv. of New England College of

Osteopathic Medicine 1994Biddeford, ME

Background

Ø Internship- Brown University/ Rhode Island Hospital, 1995

ØResidency-Orthopedic Surgery, Oklahoma State University College of Osteopathic Medicine/Tulsa Regional Medical Center, 1999

Ø Fellowship- Lower Extremity and Joint Reconstruction, State Univ. of NY at Buffalo, Kenneth Krackow, MD, 2000

Clinical Experience

Ø2000-Fellowship, Kenneth Krackow, MD-1st generation Stryker Navigation and robotic surgery

ØIntroduced computer assisted total knee replacement to State of Oklahoma 2001

ØAdjunct Clinical Assistant Professor-OSUCOM Orthopedic Residency

ØAlmost exclusively TJA practice

Did You Know?

ØIn 2006, 1 million TJA’s performed in US

ØBy 2030, demand for TKA projected to grow by 673% to 3.48 million TKA/yr

Did You Know?

ØIn 2005--38,300 Rev. TKA performed in US

ØDemand for Rev. TKA will double by 2015

ØBy 2030, demand for Rev. TKA will grow 601% to 268,200/yr

Did You Know?

ØCost of revisions-- $3.2 billion

Ø80% of TJA in US are performed by Surgeons who do < 20 TJA/year(<2/month)

Did you Know?

ØPt’s < 65 exceed 50% of TKA

ØPt’s <65 exceed 50% of Rev. TJA

Common Causes of Revision TKA

ØInfection (25.2%)ØImplant loosening (16.1%)ØMost commonly performed @large,

urban, nonteaching hospitals in Pt’s 65-74 y/o

ØAve. LOS 5.1 daysØAve. charges $49,360

Total Knee ReplacementØIndicationsØSevere disabling pain from arthritis affecting more than one compartment of the knee ØFailed non-operative treatmentØX-rays must show advanced arthritis

Ø95% good or excellent resultsØ95% 15-20 yrs survival

Evaluation

ØHistoryØReview of RecordsØPhysical ExamØDiagnostic TestingØLabs

Evaluation

ØHistoryØDifficulty with ADL’sØCatching, grinding, lockingØSwellingØPain-at rest, w/ activityØLocationØTreatments-present/prior ØImprovement?

Physical ExamØSwelling, effusion, warmth, erythema?ØPalpation- joint lines, med./lat. patella

retinaculum, inf./sup. pole, patella tendon and tubercle, add. tubercle

ØLigament exam--pivot shift, quad. active test, lochman’s, ant. draw

ØAROM/PROM—flex. contr., ext. lag.?ØMotor, sensory, DTR’s, SLR

Diagnostic TestingØX-Rays

ØA/P, Lat., WBØDifferential Injection

ØKnee vs. HipØMRI

ØKnee vs. Lumbar SpineØEMG/NCS

ØNeuropathy

Non-operative Treatment

ØLifestyle changes/activity modification

ØNSAID’s

ØGlucosamine/Chondroitin sulfate??

Non-operative TreatmentØSteroid injection

ØCan worsen degenerationØOne to three times

ØHyaluronic acid injectionØBest results with mild degeneration, mild

mechanical axis deviation and no meniscal injury

ØCan help persistent symptoms after arthroscopy

Non-operative Treatment

ØPhysical TherapyØStrength and flexibility

ØBracingØOrthoticsØAmbulatory assistance device

Radiographic Findings in Advanced Arthritis

ØBone spursØComplete/near complete joint space lossØSevere joint deformityØBoney erosion

Total Knee Replacement

ØFemur– highly polished CoCrØTibia– CoCr or TitaniumØPatella– UHMWPEØ“all poly”ØMetal backed

Total Knee Replacement

After Surgery

Ø24 hours in hospitalØHome PT for 6 weeksØOut patient PT for 4 weeksØNo driving for 6 weeks(R TKA)ØRTW at 6 wks for sedentary jobØRTW at 12 wks for high demand job

Controversies in TKA

ØCemented vs. Un-cementedØResurface vs. Retaining patellaØPCL retaining vs. PCL sacrificingØAll poly/non-modular vs. modular tibia

componentØComputer assisted robotics vs. shape

matching technology

General Principles in Total Knee Replacement

Ø Neutral mechanical axisØ Classical alignment

Ø Joint line 90 degrees to mechanical axisØ Anatomic alignment

Ø Joint line 3 degrees oblique to mechanical axisØ Symmetric flexion and extension gaps

Classical Alignment

Anatomic Alignment

Total Knee Replacement:6 degrees of Movement

ØFlexion and extension

ØVarus and valgus

ØInternal and external rotation

Consequences of Mal-positioning: Femoral Component

ØExcessive flexionàdecreased ROM in flexion of knee, over sizing

ØExcessive extensionànotching femur increasing risk of fracture distal femur

Consequences of Mal-positioning: Femoral Component

ØExcessive varus or valgusàligament instabilty and mal-alignment mechanical axis

ØExcessive distal resectionà Extension instability, ligament damage, patella baja

Consequences of Mal-positioning: Femoral Component

ØExcessive internal rotationà mal-tracking of patella or PF instability

ØExcessive distal resectionà Extension instability, ligament damage, patella baja

Consequences of Mal-positioning: Tibial Component

ØExcessive posterior slopeà flexion instability, loss of extension, impacts insertion PCL

ØLack of posterior slopeà extension instability, loss of flexion

Consequences of Mal-positioning: Tibial Component

ØExcessive internal rotationà mal-tracking patella, PF instability

ØExcessive varus or valgusà ligament instability, mal-alignment mechanical axis

ØExcessive resectionà general instability, patella tendon damage

Consequences of Mal-positioning:Patella Component

ØAsymetric resectionà PF mal-tracking, anterior knee pain

ØOver replacingà 5 degrees loss of flexion/ 1 mm

ØUnder replacingà 5 degrees of extension lag/ 1 mm

Total Knee Replacement

ØLongevity dependant upon alignment and ligament balance

ØFailure usually results from polyethylene wear and loosening of one or all components

Total Knee ReplacementPatient Factors Affecting Longevity

ØActivityØMore active

ØAgeØYounger patients usually more active

ØWeightØJoint reactive forces in knee 3 X body

weight in normal walking, 6 X running

Total Knee ReplacementSurgeon Factors Affecting Longevity

ØAlignmentØMal-alignment of as little as 3 degrees can have negative impact on survival

ØLigament balanceØResurface patella vs. Unresurfaced

Total Knee ReplacementOther Factors Affecting Longevity

ØFixationØCemented vs. un-cemented vs. hybrid

ØPCL retaining vs. PCL substituting vs. PCL sacrificing

ØMetal backed vs. all poly patella

The Literature is ClearØCorrect limb alignment is

crucial for TKRØMechanical Axis within 3° of

neutralØCAS-TKR is more Accurate

than Conventional TKRØ CAS-TKR is also more

Accurate than CCB-TKR or PSG’s*

*Accuracy of CT-Based Patient SpecificTotal Knee Arthroplasty Instruments

~ Francis B. Gonzales, MD, C. Anderson Engh, Jr., MD, Deborah Ammeen, BS, Robert Hopper, PhD

AAHKS 2010 Poster Presentation.

Total Knee ReplacementNew Technology

ØComputer Assisted Robotic Surgery

ØShape Matching Technology (SMT)

Computer Assisted Robotic Total Knee Replacement

ØMore accurate and reproducible alignment

ØVirtually eliminates issues of mal-alignment and poor ligament balance

Computer Assisted Robotic Total Knee Replacement

ØGPS for the bodyØProvides surgeon with comprehensive

understanding of the patient’s knee mechanics before any bone is cut

ØAllows surgeon to make adjustments within a fraction of a degree before bone is cut

ØUseful in difficult anatomic situations and retained hardware

Computer Assisted Robotic Total Knee Replacement

ØTheoretically improve longevity of TKA

ØUseful in conjunction with minimally invasive techniques

Shape Matching TechnologyØUses CT scan or MRI to make 3D mold of

patients knee.ØThe surgeon picks the thickness and alignment

of the cuts with a computer programØUsing a computer program, customized blocks

are made to match the moldsØThese blocks are fixed to the bones with pins

during surgery and will allow the bone cuts to made as planned with the computer.

My PracticeØ134 knees- 114 varus, 20 valgusØPre op deformity

ØRange 15 varus -11valgusØAve. varus-7.18ØAve. valgus-3.35

ØPost op deformity ØAve,. Varus-1.61ØAve valgus-2.37

Ø92% < 3 degrees mal-alignmentØ95% < 4 degrees mal-alignment

Conclusions:Total Knee Replacement

ØChallenging procedure to perform correctly because of the 6 degrees of movement

ØAccurate positioning of components is critical for longevity and function in knee replacement

ØComputer assisted robotic technology reduces variability in component placement improving function and longevity

Thank You