Freedom Knee Surgical Technique Print

7/27/2019 Freedom Knee Surgical Technique Print

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Freedom Total Knee System

Surgical Technique


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CONTENTS

Overview 3

Preoperative Planning 3

Incision and Exposure 4

Femoral Preparation 5

Tibial Preparation 10

Patella Preparation 13

Trial Reduction and Gap Balancing 14

Implantation 14


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OVERVIEWSurgical technique is an important actor in providing consistent and reproducible results.Basic principles o total knee replacement surgery should be maintained throughoutthe procedure. The surgeon must pay close attention to balancing the lexion andextension gaps, accurately sizing the emoral, tibial, and patellar components,positioning the emoral component in appropriate external rotation, removingexcessive osteophytes o the posterior condyles, maintaining the joint line andimplanting the inal components using modern cementing techniques.

Preparation o the emur, tibia and patella can be achieved independently basedon surgeon pre erences. The instrumentation is not dependent on sequential stepsduring preparation o the three components. The principles o measured resection(replacing removed bone with equal amounts o implant) are used to provide thisversatility during the operation. At the time o trialing the implants, we recommendthat the surgeon assess overall alignment, extension angle, varus/valgus stability,

lexion angle, patello emoral tracking and anterior posterior stability.

PREOPERATIVE PLANNING The angle between the mechanical and anatomic axis o the emur should bereproduced intraoperatively. You may contact your Maxx Medical representative orx-ray templates. The tibial component should be positioned perpendicular to themechanical axis o the tibia. The inal sizes must be determined intraoperativelyas x-rays only provide an approximation. Please contact your Maxx Medicalrepresentative i you anticipate using the smallest or largest size, as it is our policy toprovide components o every size in the system to accommodate any situation thatmay occur during the procedure.

The surgical technique outlined is speci ic to the Freedom Total Knee System. Thetechnique described uses the classical anterior midline incision to access the knee joint via a medial parapatellar ar throtomy. However the subvastus and midvastusapproaches can readily be used with the same instrumentation. Your Maxx Medicalrepresentative can supply instrumentation to accommodate your pre erred approach.

The emoral A/P sizing guide is an anterior re erencing system that helps provide aconsistent lexion gap. Regardless o the instrumentation used, equalization o the

lexion and extension gaps is imperative to ensure knee stability.


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INCISION AND EXPOSUREPrior to incision, the superior pole o the patella ismarked with the knee exed at 30. The tibial tubercle isidenti ed and marked. An anterior midline longitudinalincision is made rom a point slightly proximal to thesuperior pole o the patella passing just medial to thetibial tubercle at its distal margin. I signi cant tensionis noted along skin edges, the incision should beextended to minimize risk o wound-edge necrosis.

Visualize the extensor mechanism without underminingthe medial and lateral skin aps. We recommend usinga surgical marker to mark the medial parapatellararthrotomy line starting rom the medial edge o theextensor mechanism along the medial border o thepatella to the medial edge o the patella tendon (Fig. 1).Be cautious not to transect the quadriceps in thinner

patients with a small quadriceps tendon, as this couldcompromise postoperative rehabilitation protocols.Per orm the arthrotomy with the knee in 30 o exion.

Extend the leg and excise the at pad under the patellatendon. Release excessive osteophytes along themargin o the patella. Retract the patella laterally withthe knee in extension and release the patello emoralligaments. At this point, release o the anterior horno the lateral meniscus will acilitate retraction o theextensor mechanism to the lateral side. Per orm an

abbreviated medial release o the proximal so t tissueattachments to the proximal tibia in standard ashion.

Figure 1


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INCISION AND EXPOSURE (continued)Release the anterior cruciate ligament and removethe medial and lateral meniscus. This will allow urtheredge exposure o the proximal tibia. Place retractorsalong the medial and lateral sides o the tibia or ullvisualization.

NOTE

I the Freedom CR emoral component isbeing used, be care ul not to disrupt theattachment o the posterior cruciate ligament(PCL) to the medial emoral condyle.

FEMORAL PREPARATION

Establishing femoral entry site

Using the emoral step drill, make an entry hole intothe medullary canal o the emur (Fig. 2). The startingpoint should be anterior to the PCL attachment on themedial emoral condyle, just medial to the midline axis

o the emur. Suction the medullary contacts prior toinsertion o the distal emoral cutting guide (DFCG) toreduce the potential o at embolization.

Figure 2


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FEMORAL PREPARATION (continued)

Distal femoral valgus angle prepara on

Con rm that the correct side (Right or Le t) is orientedon the guide (Fig. 3). Slowly insert the DFCG. Advance

the DFCG until the endplate rests securely on thecondyles. Secure the distal emoral cutting jig to thedistal emur with pins. Release the adapter and removethe distal emoral cutting guide using the detachable slap, i necessary.

NOTE

The distal emoral cutting jig (Fig. 4) cutsthe distal emur in a measured resection. Thestandard cut is 9mm. An optional cut slot is

available which provides an additional 4mmo resection. Additional holes allow the block to be repositioned in 2mm increments.

Use the oscillating saw to make the distal emoralace cut at 6 valgus (Fig. 5 and 5A). Additional valgus

adaptors are available to provide 4 and 8 valgus cutsas well.

Figure 3

Figure 4

Figure 5

Figure 5A


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FEMORAL PREPARATION (continued)

Sizing the distal femur

Secure the emoral A/P sizing guide to the distal aceo the emur and con rm that the correct side is read

(Right or Le t). Use the stylus to adjust the height o thesizing guide to the highest point on the anterior aspecto the distal emur. Once adjusted, place headless pins into the two 3 external rotation slots (Fig. 6) Read thesize using the indicator.

NOTE

The emoral A/P sizing guide is a single-unit,reversible anterior re erencing instrument(Fig. 7). It allows or sizing o both the right

and le t emur based on the orientation o theguide. It also allows the surgeon to set the

emur in 3 or 6 o external rotation, based onthe posterior condylar axis. Intraoperatively,the rotation can be veri ed using theanteroposterior axis (Whiteside line) (Fig. 7A)or the surgical transepicondylar axis o the emur.

Comple ng the distal femoral prepara on

Position the 5-in-1 cutting block over the headless pins, centering the block on the M/L dimension o the

emur (Fig. 8).

Figure 6

Figure 7

Figure 7A

Figure 8


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FEMORAL PREPARATION (continued)Secure the 5-in-1 cutting block to the emur using threaded pins (Fig. 9, 10). Con rm that the anterior cutwill not notch the anterior cortex o the emur. Removethe headless pins . Additional stability is achievedwith the use o two 6.5mm cancellous screws placedthrough the lug holes.

Using an oscillating saw with a 1.27mm thicknessblade , prepare the emur in the ollowing order(Fig. 11, 12).

1. Anterior cut

2. Posterior condylar cut

3. Superior champher cut

4. In erior champher cut5. Trochlear cut

NOTE

I positioned in external rotation correctlyon the distal ace o the emur, then moreposteromedial emoral condyle would beremoved compared to the posterolateral

emoral condyle. Be care ul not to transectthe attachment o the medial collateralligament or the lateral collateral ligamentduring resection o the posterior condyles.

I screws have not been used to hold the 5-in-1 cuttingguide, then use a 5mm peg drill to make the two lugholes at the appropriate locations o the distal emur.

Figure 10

Figure 9

Figure 11

Figure 12


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FEMORAL PREPARATION (continued)I implanting a posterior stabilized (PS) design, see PSbox cut preparation below. I opting to use the cruciateretaining (CR) design, proceed to Removing theposterior osteophytes section.

PS box cut prepara on

Secure the same size box cut guide to the emur.With a reciprocating saw, use the guide to make thebox cut on the distal emur (Fig. 13). Be care ul notto undermine the medial or lateral condyles and risk

racture.

Remove posterior osteophytes

Using an osteotome or rongeur (Fig. 13A), remove anyposterior osteophytes. The emur is now prepared toaccept either the cruciate retaining (CR) or posteriorstabilized (PS) emoral component. The preparationshould be done in a measured resection so the amounto bone removed will be duplicated by the implantwhen positioned on the distal emur.

NOTE

The above emoral preparation was donein a measured resection. Trial componentscan be used or gap balancing, a ter tibialpreparation.

Figure 13

Figure 13A


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TIBIAL PREPARATION

Extramedullary bial alignment and proximalbial resec on

Align the tibial cutting guide (TCG) and stabilize the

guide using the spring around the ankle (Fig. 14). Usethe gross adjustment knob and align the TCGwith themechanical axis o the tibia in the coronal and sagittalplanes. Secure the guide with one pin . At this time,con rm parallel alignment o the TCG to the mechanicalaxis in both planes. Use the ne adjustment knob atthe proximal end o the TCG to adjust the height o thecutting slot (Fig. 14A). A tibial stylus can be used at thispoint to approximate resection height at either 2mmbelow the lowest point or 9mm below the highest pointon the proximal tibia. Secure the TCG to the bone with

two pins . Tighten all knobs .OR

Intramedullary bial alignment

Access to the intramedullary canal o the tibia is madewith the 8mm emoral step drill . The uted rod romthe IM tibial alignment assembly is advanced intothe canal and the collar o the assembly is brought torest on the sur ace o the tibia (Fig. 14B). An externaldrop rod can then be used to veri y alignment withthe mechanical alignment axis o the tibia. A stylus isplaced into the cut slot to approximate either a 2mmcut rom the lowest point o the proximal tibia or 9mm

rom intact cartilage (Fig. 14B). The tibial cut block ispinned in place, and all adjustment knobs are released. The assembly is disengaged rom the cut block andremoved. The proximal tibial cut is made in thestandard ashion.

NOTE

The cutting slot on the TCG is angled to providea 3 posterior slope. I the PCL is being retained,be cautious not to transect the PCL with the sawblade. We recommend placing a -inch osteotomein ront o the PCL to ensure it is protected rominadvertently passing the saw blade too arposterior (Fig. 15).

Figure 14

Figure 14A

Figure 14B

Figure 15


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TIBIAL PREPARATION (continued)

Re ning the proximal bial face cut

Con rm alignment using the tibial alignment block and tibial alignment rod. Make adjustments to

the proximal tibial ace cut, i necessary, to ensurealignment o the rod with the mechanical axis o thetibia (Fig. 16).

NOTE

Rotational alignment can also be adjustedusing the optional ree-foating baseplate. Thebaseplate can be reely placed on the proximalsur ace with an articular sur ace liner o theappropriate thickness. The knee is reduced andtaken through a range o motion. This allowsthe baseplate to reely locate on the proximalsur ace o the tibia. With the knee in extension,mark the midline o the baseplate on the bonecorresponding to the laser etch mark ound in the

ront o the baseplate. This serves as a guide toreproduce the rotation o the baseplate.

Tibial baseplate prepara onand rota onal alignment

Place the appropriately sized tibial baseplate (Fig. 17)on the resected sur ace o the proximal tibia. Theappropriately sized baseplate should have bony supporton all sides with no overhang (Fig. 17A). Use the tibial alignment rod through the tibial tray coupler to adjustrotation o the tibial baseplate. The medial 1 3 o thetibial tubercle should serve as an anatomic landmark toguide rotational placement o the baseplate. Secure thetibial baseplate with long pins (Fig. 17B) and disengagethe tibial tray coupler .

Figure 17A

Figure 17

Figure 17B

Figure 16


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TIBIAL PREPARATION (continued)Place the tibial broach housing on the tibial baseplate (Fig. 18).

Reaming the proximal bia

Using the tibial entry reamer, gently ream the proximaltibia until the marked groove on the reamer reachesthe top o the tibial broach housing (Fig. 19). I the metal-backed tibia tray is being used, go to Broachingthe tibia. Otherwise, skip to Trialing the tibialcomponents.

Broaching the bia

Gently tap the tibial broach (Fig. 20) through the tibial broach housing until it reaches the endpoint (Fig. 20A).Use the detachable slap to remove the tibial broach. Release the guide.

Figure 18

Figure 20

Figure 20A

Figure 19


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TIBIAL PREPARATION (continued)

Trialing the bia components

Place and impact the appropriate emoral component ,ollowed by the tibial baseplate , insert thickness trial

tibial insert into the tibial baseplate (Fig. 21). Reducethe knee and trial the components (Fig. 21A).

PATELLA PREPARATION The preparation o the patella should be done withthe patella everted and the knee exed to 30. Theminimum thickness o the resected patella should be8mm. Overstufng the patello emoral joint may leadto exion loss, while leaving a thin patella may lead to

racture or early loosening. Use a caliper to help decidethe amount o resection that is required.

Once the patellar sur ace is resected (Fig. 22), use the patellar drill guide to assess the size o the patella.Using the patellar drill guide and the peg drill (Fig 22A), drill three holes in the remaining patellarbone. Place the patella trial (Fig. 22B) onto theresur aced patella and begin range o motion toevaluate patellar tracking.

Figure 21A

Figure 21

Figure 22

Figure 22A

Figure 22B


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TRIAL REDUCTION AND GAP BALANCINGPer orm a trial reduction o the components (Fig. 23).Check alignment, varus/valgus stability, extension,patello emoral tracking, anteroposterior stability and

exion degrees. Use a gap balancing chart to adjust andmodi y any imbalance in the knee. So t tissue releasescan be per ormed as necessary to allow or ne tuningthe tension in extension and exion.

IMPLANTATIONUsing the standard mixing protocol or the bonecement, mix and prepare the bone cement or

cementing the implants.We recommend the ollowing order o implantation.

1. Tibial component

2. Femoral component

3. Patellar component

4. Tibial articulating sur ace

Prior to cementing, irrigate the bone sur aces anddrill sclerotic areas with a 1 8 drill bit to a depth o approximately 1 8. Firmly press cement into the bonesur aces (Fig. 24), including the reamed keel entry hole,to allow or adequate interdigitation. Place cement onthe undersur ace o the tibial component and rmlyimpact the tibial component (Fig. 25) into place usingthe tibial impactor. Remove excess cement.

Figure 24

Figure 23

Figure 25


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IMPLANTATION (continued)Hyper ex the knee and dry the distal emoral bonecuts (Fig. 25A). Finger pressurize the posterior condyleswith cement. Apply bone cement to the undersur aceo the emoral component . Firmly impact the emoral component into place using the emoral impactor .Remove excess cement.

I themetal-backed tibial tray is being used, irrigatethe sur ace o the tray and remove any excess debris toclear the locking mechanism. Firmly impact the selectedarticular sur ace liner into place (Fig. 26) and check tosee that the locking mechanism is engaged.

Reduce the knee and place into extension. Evert thepatella. Dry the bony sur ace o the patella. Placecement into the bone sur aces. Apply bone cementto the undersur ace o the patella implant. Place the patella implant in the resected bone. Use the patellaclamp to secure the patella implant (Fig. 26A). Trimexcess osteophytes and remove excess cement.

Closure is per ormed in the usual manner (Fig. 27).

Figure 26

Figure 25A

Figure 26A

Figure 27


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For more informa on about Freedom Kneeplease contact your local representa ve.

www.maxxmed.com

Freedom Knee is manufactured by Maxx Orthopedics, Inc. FREEDOM and FREEDOM KNEE are Registered Trademarks of Maxx Orthopedics, Inc.

2012 Maxx Orthopedics. All rights reserved. Updated January 2012.

Maxx Orthopedics Brochure No MXO-MP00005-R04

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Freedom Knee Surgical Technique Print