Total Knee Replacement

Category: Education

Presentation Description

Describes the steps for PFC TKR By Dr Aditya L Kekatpure


Presentation Transcript

Total Knee Replacement:

Total Knee Replacement Dr ADITYA L KEKATPURE M.B.B.S,D.Ortho,DNB


Indications: Severe pain and functional disability d/t: -OA - Rhematoid Panarthritis -Severe patellofemoral arthritis in elderly Osteonecrosis with subchondral collapse of femoral condyle Deformity and varus / valgus laxity


Contra-indications: Active knee sepsis Extensor mechanism discontinuity or dysfunction Stable arthrodesis Genu recurvatum Relative contraindications: -Atherosclerotic disease of operative leg,venous stasis with recurrent cellulitis -morbid obesity,Neuropathic arthropathy

Basic Principles of TKR::

Basic Principles of TKR: Restoration of mechanical axis Restoration of joint line Balance of soft tissue E qualize flexion and extension gaps R estore patellofemoral alignment and mechanics

Preoperative planning::

Preoperative planning: All routine blood investigations Diabetic profile Radiographic evaluation

Preoperative Radiographs::

Preoperative Radiographs: Standing AP view Lateral View Merchant View

PowerPoint Presentation:

Mechanical axis of femur is in 3 degrees of valgus from vertical axis of body Anatomical axis is in 6 degrees of valgus from mechanical axis of LL and 9 degrees of valgus from true vertical axis of body Anatomical axis of tibia lies in 2 to 3 degrees of varus from vertical axis of body

Surgery ::

Surgery : Anaesthesia : -Spinal Anaesthesia -General anaesthesia Position of patient: Supine

Surgical approaches::

Surgical approaches: Medial parapatellar arthrotomy Subvastus (Southern )approach Midvastus approach Rectus Snip approach

Surgical Approaches::

Surgical Approaches: Subvastus Approach Medial Parapatellar retinacular Approach

Midvastus approach:

Midvastus approach Differs from subvastus approach in that VM is split in line with its fibres rather than subluxating laterally in its entirety Split starts at superomedial border of patella and extends proximally and medially towards the intermuscular septum

Surgical technique for implanting posterior Stabilized prosthesis::

Surgical technique for implanting posterior Stabilized prosthesis: - Medial parapatellar arthrotomy approach - P eriosteum of the proximal medial tibia is raised - Laterally a small cuff of periosteum is raised in continuity with patellar ligament

PowerPoint Presentation:

Patella along with the extensor mechanism retracted laterally and knee is placed in full flexion Cruciate ligaments and meniscii are excised A curved osteotome is passed along the medial tibial border to release the menicotibial ligament and promote anterior subluxation of tibia

Coronal plane ligament balancing:(Release on the concave side of deformity) :

Coronal plane ligament balancing:(Release on the concave side of deformity) Varus Knee: -Medial release needed - Osteophytes - Deep Collateral ligament( Meniscotibial ligament) - posteromedial corner with Semimembranosus -Superficial MCL and pes anserinus complex

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With the knee in maximum flexion ,the tibia is rotated externally with posteromedial dissection Medial menisectomy is performed and dissection is directed to the lateral side

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A 90 degree Hohmann is positioned between the everted patella and distolaterla femur exposing the laterla patellofemoral ligament which is incised

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Capsule is dissected free from the infrapatellar fat pad and a lateral menisectomy is performed The lateral genicular artery is coagulated

Bone Preparation :

Bone Preparation Based on following principles: 1)Appropriate sizing of individual components 2)Alignment of components to restore the mechanical axis 3)Recreation of equally balanced soft tissue in flexion and extension 4)Optimal patellar tracking

Tibial Alignment : :

Tibial Alignment : Knee is placed in maximum flexion Tibia is distracted anteriorly and stabilised The upper cutting paltform is secured onto the proximal uprod of the tibial alignment device

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Translate the lower assembly AP to align it parallel to the tibial axis Mediolateral alignment is approximately 3-5mm medial to the transaxial midline.

Upper platform::

Upper platform: Align the upper cutting platform with the medial third of tibial tubercle and the medial margin of the intercondylar eminence

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Exact level of resection will vary according to patients anatomy As the mediolateral transverse plane of the tibial plateau is usually 3 degrees from the perpendicular and projected cut is perpendicular to the anatomic axis more bone is removed from lateral condyle Tibial insert thickness is 10mm,12.5mm,15 mm and 17.5mm

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The outrigger of the stylus is marked nonslotted and slotted Use nonslotted for resection from the surface of the the block And slotted for resection through the slot There is 4mm difference between between the slot and the top surface

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Insert the cylinder foot into the slot of cutting block and adjust to the appropriate level It is caliberated in 2mm increments ,indicating the amount of bone and residual cartilage to be resected

Tibial Stylus::

Tibial Stylus: Level of 10mm is suggested when resection based on the less involved condyle and level 0 when resection b/on more involved condyle

Securing the platform:

Securing the platform Platform secured to tibia with steinmann pins

PowerPoint Presentation:

Resection done using 1.19mm saw blade

Entering the medullary cavity::

Entering the medullary cavity: Medullary canal entered at the midline of the femoral trochlea 7-10 mm anterior to the origin of PCL to a depth of about 5-7 cm using 8mm drill

Intramedullary Rod::

Intramedullary Rod: Rod along with handle is inserted slowly into the canal to the level of the isthmus to confirm unobstructed passage Rod is fluted to relieve intramedullary pressure and permit release of bone marrow ,avoiding embolisation

Femoral Locating Device:

Femoral Locating Device Desired valgus angle with the appropriate right /left destination is set and locked into front of the locating device Angle can be set from 0 to 9 degrees in 1 degree increments After removing handle of intramedullary rod locating device is placed over the rod

External Alignment System:

External Alignment System A rod placed through the apex of the arch should point to the centre of femoral head This is determined intraoperatively by ensuring that the rod passes medial to ASIS

Femoral rotational alignment methods :

Femoral rotational alignment methods AP axis method Epicondylar axis method Posterior Condylar axis method Tibial alignment axis Tensiometer method

Distal Femoral Cutting Block::

Distal Femoral Cutting Block: Cutting block is assembled onto the caliberated The resection of the more prominent condyle inclusive of residual cartilage ,will correspond to the distal dimension of the femoral prosthesis .

Distal Femoral Cut::

Distal Femoral Cut: After satisfactorily positioning the distal block ,an oscillating saw is used to make the distal femoral cut For knees with preoperative flexion deformity ,an optional slot is used to resect an additional 3mm of femoral bone .

Evaluating the extension gap:

Evaluating the extension gap Knee placed in full extension and lamina spreaders applied medially and laterally Peripheral osteophytes have to removed at this stage ,since they may influence ligament balancing Extension gap must be rectangular in configuration,when it is trapezoidal ,the bilateral soft tissue must be balanced In extension ,the spacer block is assembled from the base element and insert shim of appropriate thickness The spacer indicates the appropriate thickness of tibial insert

Sizing the femoral Component::

Sizing the femoral Component: Careful preoperative planning including application of templates to lateral radiographs ,is critical to sizing of femoral component Priority is given to re-establish the A/P dimension ,as this will restore the normal kinematics and quadriceps function Undersizing will cause looseness in flexion and possible notching of the anterior femoral cortex

Femoral Sizing:Anterior Down:

Femoral Sizing:Anterior Down Seat the chosen sizing guide flush and centred over the prepared distal femoral surface Pass the stylus over the anterior cortex immediately proximal to the articular surface At the appropriate level where the stylus is not impeded ,turn the stylus locking knob clockwise until it is tight ,to fix its position

PowerPoint Presentation:

Use the sizing guide to position the femoral cutting block so the anterior flange of the prosthesis is flush with the anterior cortex of the femur When the sizing device indicates a whole size ,8mm will be resected from the posterior condyles corresponding to posterior condyle thickness

Rotational alignment/Anterior down:

Rotational alignment/Anterior down The anterior and posterior cuts must be externally rotated in order to be parallel to the tibial cut and to provide rectangular flexion gap Care should be taken if there are deficient medial or lateral posterior condyles as they may affect femoral rotation

Anterior femoral cut:

Anterior femoral cut Anterior cut is made with the blade of the oscillating saw flush against the cutting block 1.19 mm saw blade is recommended

Femoral Chamfer Cuts:

Femoral Chamfer Cuts Chamfer cuts are made through the slotted 4 in 1 block The block is then removed

Femoral cutting Guide:

Femoral cutting Guide Place the femoral cutting guide onto the prepared femur and position it so that lateral flange meets the lateral margin of the femur Check the cutting line for the posterior cut

PowerPoint Presentation:

Perform the posterior cut through the slots provided

Femoral notch cut::

Femoral notch cut: A small blade (13mm*75mm*1.19mm)) is recommended to cut the sides of the notch

Femoral notch trial:

Femoral notch trial Femoral notch trials may be used to check the notch cuts

Clearing posterior condyles:

Clearing posterior condyles Posterior condyles have to be cleared of the overhanging bone or osteophytes

Gap Technique::

Gap Technique: Flexion and extension gaps must be equal If extension gap smaller than flexion gap remove more bone from the distal femoral cut surface or release the posterior capsule from the distal femur If flexion gap is smaller than extension gap remove more bone from the posterior femoral condyles If F gap=E gap, but there is no space for desired prosthesis ,remove more bone from proximal tibia because it affects F/E gap equally If F=E gap, but lax, use larger spacer block and a thicker polyethylene insert to obtain the stability

Patella Resurfacing:

Patella Resurfacing Important to maintain saggital dimension and to preserve adequate bone stock & to free sufficient soft tissue to position the callipers the normal range of the greatesh sagittal dimension is 20-30mm Patella size Resection 32mm 8mm 35mm 8.5mm 38mm 9mm 41mm 11.5mm

Patella Cutting Guide:

Patella Cutting Guide Synovial tissue is cleared to the level of the insertion of quadriceps mechanism and patellar ligament Prongs of the knurled forceps are adjusted to the predetermined thickness of residual patella

Patella resection & drilling::

Patella resection & drilling:

Tibial Plateau Preparation & Initial Trial Reduction:

Tibial Plateau Preparation & Initial Trial Reduction Alignment of tibial component is projected to a point slightly medial to the tibial tubercle Alignment of a symmetrical component with the posterior margin of tibial plateau will usually result in some internal rotation of tibial component

PowerPoint Presentation:

With a symmetrical component ,some degree of posterolateral overhang is expected because the medial tibial plateau is larger than lateral

Trial Reduction :

Trial Reduction Position appropriately sized femoral trial onto the femur and trial tibial tray onto resected tibial surface. Position the pinned evaluation bullet into the cut out of the tibial tray Select the tibial insert that matches the femoral size onto the tibial tray The tibial tray is centered on the junction between the medial and central one third of the tibial tubercle

PowerPoint Presentation:

After removing the alignment handle and with trial prosthesis in place ,extend the knee and check for anteroposterior & mediolateral stability Assesement of bearing rotation and patellofemoral tracking can also be achieved In case of instability insert a trial with the next greater thickness and repeat reduction Select the insert with greatest stability in flexion and extenion but still allowing full extension

Tibial Finishing ::

Tibial Finishing : After removing the tibial bearing and femoral components the tibial tray is secured with fixation pins M.B.T drill bushing is seated on tibial tray

PowerPoint Presentation:

Assemble the drill stop onto the M.B.T drill and position at the selected tray size MBT drill creates a cavity that is line to line with punch bushing and final implant TRAY SIZE DRILL STOP SEATING CEMENT MANTLE 1-1.5 2-3 0.5mm per side 4mm distal 2-3 4-7 -same 4-7mm Drill bottoms out on tibial tray same

PowerPoint Presentation:

Insert the M.B.T keel punch bushing into the M.B.T tibial tray ,using the M.B.T punch bushing impactor /extractor When complete the superior surface of the punch bushing should flush with superior surface of tibial tray trial

PowerPoint Presentation:

Assemble the universal handle to the appropriately sized M.B.T keel punch and insert it into M.B.T punch bushing ,avoiding malrotation Impact till shoulder of the punch is in even contact with the M.B.T punch bushing Disconnect the universal handle ,leaving the M.B.T punch in place

Additional trial reduction ::

Additional trial reduction : Performed after central stem preparation With the trial prosthesis in place ,knee is fully extended and the A/P and M/L stability is noted A insert that gives greatest stability with full extension and flexion movement is selected

Implanting Components:

Implanting Components After thorough cleansing the entire site with pulsatile lavage bone cement is prepared and applied in its low viscosity state

PowerPoint Presentation:

Assemble the universal handle onto the M.B.T tray impactor and carefully insert the tibial tray, avoiding malrotation After full insertion mallet blows are given to the top of the universal handle

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As the cement polymerises ,the trial femoral component and M.B.T trial post into the central stem and the trial tibial insert are used and knee is placed in full extension and even pressure is maintained across the bone/implant interface Care is taken not to hyperextend the knee as this could cause unequal pressure and posterior lift-off of the tibial tray Once cement is set ,place the knee in flexion and the trial components are removed The extruded cement is removed with special attention to posterior compartment and entire periphery

Femora component:

Femora component Entry hole at the medullary canal is plugged with cancellous bone All surfaces are thoroughly cleaned with pulsatile lavage Cement is applied to bone at anterior ,anterior chamfer & distal surfaces and to the inner surface of the component at posterior condylar recesses Implant is assembled on the femoral inserter Care is taken for orientation of implant

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Inserter is released and seating completed with the femoral impactor and a mallet All extruded cement is cleared with a scalpel and curette The final tibial insert may now be inserted

Patellar Component:

Patellar Component Cut surface are cleaned Cement applied Component inserted Patellar clamp is used to fully seat and stabilise the implant as the cement polymerises Excessive compression should be avoided as it can fracture the osteopenic bone

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Finally range of motion is checked and patella checked for maltracking Pulsatile wound lavage is given Tourniquet is released Hemostasis achieved

Wound Closure:

Wound Closure Extensor retinaculum repaired Wound closed in layers over drain tube Sterile dressing is applied Knee immobilised in long knee brace

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