Total knee replacement (posterior stabilised)- Visionaire Genesis II (Smith and Nephew)

Lateral photograph showing position of props one against tourniquet and the distal bolster for control of patient’s foot.

Pre-operative evaluation of coronal deformity of lower limb, in this case the patient has valgus osteoarthritis.

Test the competency of the collateral ligaments in the valgus knee. One must make sure that the MCL is competent and has a definitive end point. In cases of extreme valgus play or an incompetent MCL a hinged total knee replacement is needed. In this case the valgus deformity is not extreme and the MCL was competent.

Analyse the leg for a pre-operative fixed flexion deformity of the knee. Where a pre-operative fixed flexion deformity exists increased distal femoral bone resection cuts may be required to allow the knee to straighten and posterior release might be needed. Note these factors should be identified before the patient comes to theatre and are readily observed in the clinic.

Pre-operative visionaire plan, measurement of the valgus alignment of the leg and identification femoral and tibial mechanical alignment.

Prepped and draped limb. Here the limb has been covered with a proprietary Ioban skin incision drape. I favour this technique when the skin is healthy as it allows visualisation of the tibia throughout its entire length and omits the need for bulky drapes distally which can get in the way of the alignment rod instrumentation.

A mid-line incision is made in the skin. This starts about a hand’s breadth proximally from the centre of the patella to just below the tibial tubercle distally.

Reflect the soft tissues both medially and laterally to expose the quadriceps tendon proximally, the patella in the centre of the wound and the patella tendon distally. Use a single plane of dissection until you can see enough of the extensor mechanism. Excise any prepatella bursa if inflamed.

Identify the natural rolled edge of the patella tendon medially (illustrated here with the forceps). This is an important landmark when making your medial para-patella approach. Incise along the border of the medial patella tendon from the patella superiorly to the tibial tubercle distally. Skirt the incision around the patella medially proximally until you reach the quadriceps tendon where a 5mm cuff of tendon should be left medially as you extend up the quadriceps tendon leaving the majority of the tendon lateral to the incision.

Post-medial para-patella approach.
The patella has been everted and placed in the lateral side of the knee. Start with the knee in extension, evert the patella – then gradually flex the knee up. Be careful in the stiff knee you can avulse the patella tendon off the tibial tubercle. The femoral condyles are now exposed. The patella can be left to rest against the lateral border of the femur and not inverted – this depends on surgeon preference or may only be possible in the tighter knee.

Exposing the medial side of the knee.
Stay on the tibial bone and reflect the tissues off the medial proximal tibia starting centrally from your medial para-patella incision working around the medial side of the tibial plateau. Note this is a valgus case and the release should be minimal. In the more fixed varus cases this release needs to be more extensive often passing the “equator” of the plateau.

Remove the ACL from the femoral notch, in this case I also proceed to move the PCL fibres releasing them off the femur as I am performing a posterior stabilised total knee replacement.

Cruciate excision. Be careful not to plunge into the deep aspects of the notch as you risk damage to blood vessels!

Remove the soft tissues only from the suprapatellar region above the articular surface of the femur, so that the anterior cortical surface is exposed. This is to expose the anterior aspect of the distal femoral bone. Don’t remove any bone or osteophytes at this stage. The cutting block is designed to fit the pathological bone anatomy.

Visionaire Plan. This is the printed plan you will get for every case. It has the mm’s of resection, the size of the components, the overall alignment of the limb and measurements you require for surgery.

Tibial (A) and femoral (B) Visionaire cutting blocks.
These 3-D printed nylon cutting jigs are prefabricated and fit the patients anatomy. They arrive sterile packed. The patients name is on the outer box and also etched onto the blocks, this has been airbrushed out on this photo. The holes in the blocks are where they are pinned to the patient (4 -femoral, 5 – tibial). The cutting blocks are made of nylon and so have some flex in them, be careful not too force the blocks onto the patient. Taking the time to remove all the soft tissues will facilitate a snug fit of the cutting block onto the bone. The blocks are valid for three months following the MRI scan. Typically they fit very well and the cuts made are accurate. Once you are used to the Visionaire system – you may find your surgical time decreases. Overall alignment has been shown to be superior than more traditional techniques.

Visionaire plan showing how the tibial and femoral cutting blocks should fit the patients tibia and femur. A virtual 3-D model is also generated during planning which you can analyse pre-operatively to see how the blocks fit.

Visionaire plan showing femoral planning, the final femoral resection cuts and how the prostheses should fit the patient. Summary of resections (mm) in text column.

Undersurface of femoral Visionaire cutting block. Note the “hook” to be placed over the femoral condyles. (see next slide). The hook is very useful at guiding accurate seating of the femoral cutting block.

Apply the femoral nylon cutting block to the distal femur. The femoral cutting block has a small hook on it that should be applied on the anterior surface of the femur pulling the component down onto the articulating medial and lateral condyles. Note only soft tissue is to be removed – do not remove any bone prior to this step. Leave the osteophytes intact as the nylon cutting block is designed to fit on the bony anatomy prior to any being removed. The block should fit snuggly on the bone with no gaps.

Once you are happy that the femoral cutting block is seated as in this picture you may then proceed to pin it to the patient.

Predrill the pin hole whilst keeping the femoral cutting block firmly applied to the femur. Don’t try and hammer in the pins without drilling holes as the block may move.

Insert the pin into the predrilled hole. Repeats steps so that all 4 femoral pins are applied to hold the cutting block.

Confirm the distal femoral lateral (pictured) and medial condyle resections with an “angel wing” before cutting the bone. Compare the cuts to the Visionaire plan and ensure they are correct.

Use a sagittal saw to resect the femoral condyles. Remove the distal pins (lateral pictured) as you cut the femoral condyle. These can be replaced once the cut is complete, before proceeding to the other condyle or left free if the cutting block is stable.

Resection of the medial distal femoral condyle. Ensure that you do not flex the saw in the aperture of the femoral cutting block. This is now more likely as the stability provided by the lateral condyle is lost once it is cut.

Remove the cutting block. Leave the two proximal pins in situ. If you need to recut the distal femur for instance if the extension gap is too tight, then the pins can be reused with the standard distal femoral cutting block from the tray (i.e. +2mm cut).

Using the patella measuring calliper from the tray you can measure the thickness of your distal condylar resections and check this against the planned resections on the Visionaire plan.

The appearance of the distal femur once both medial and lateral femoral condyles have been removed.

Confirm that your cuts are flat by using a hard metal straight edge, I use the femoral cutting block. If there is rocking then the cut surface is not flat. Recut/fine tune the resection using the Visionaire femoral block or distal femoral cutting guide using the two pins that remained in situ.

Expose the tibia for resection by dislocating the tibia anteriorly. This can be performed by levering on the tibia posteriorly with a retractor and externally rotating the tibia as you retract it anteriorly. Once dislocated I use one sharp Hohmann over the lateral rim of the tibial plateau, one further blunt Hohmann in the notch and a ring handled spike on the medial side to keep the tibia exposed.

Remove the soft tissues from the front of the tibia and any meniscal cartilage remnants. Do not remove any bone as the proximal tibial cutting block is designed to fit to include the bony anatomy including the pathological osteophytes.

Inferior surface of tibial cutting block. Note the two hooks which rest on the medial and lateral tibial plateau.

Visionaire plan showing tibial planning, the final tibial cuts and how the prostheses should fit the patient. Summary of resections (mm) in text column.

Place the tibial cutting block onto the tibia ensuring it fits the patients anatomy. The contact points for the tibial block are the medial and lateral arms onto their respective plateau and the anterior medial tibial face. The cutting block should be resting flush on all three surfaces with no gaps apparent. I find it easier to seat the anterior medial tibial face correctly first. If the block doesn’t seat correctly it is most likely the soft tissue removal was inadequate.

The tibial cutting block is pinned to the tibia using a drill followed by pin placement in each of the four holes.

3 pins are now applied two distally and one in the medial tibial plateau.

4 pins are now applied. Place the slot alignment checking jig’s flat surface into the tibial cutting blocks aperture (annotated s).

Confirm tibial cutting block alignment by using the drop rod as shown. Using the handle on this you are then able to place alignment rods down the tibial shaft to confirm you are happy with the varus/valgus position of the block in relation to the patient’s tibia.

Measure the resection levels of both the medial and lateral (pictured) tibial plateau resections and compare to the pre-operative visionaire plan. Only proceed with proximal tibial cuts if you are happy with the alignment and resection thickness.

Use a sagittal saw in the tibial cutting blocks aperture, remove the proximal pins in turn as each side of the tibial plateau is cut. The medial side has been cut in this picture and its medial pin removed to allow the saw blade to get to the posterior aspect of the tibia. Ensure you complete your cut especially on the lateral rim which is often missed.

Once the tibial cut has been made, remove the tibial cutting block and then the proximal tibial plateau is removed, start by using an osteotome to elevate it.

Using a Kocher placed on the antero-medial aspect on the resected tibial plateau’s surface. Rotate the tibial plateau laterally and using sharp dissection along its posterior rim to remove the proximal tibial bone in one piece.

Confirm that the resection is correct by measuring the thickness of each medial and lateral side of the tibia articular piece removed and compare this to the planned resection on the Visionaire plan.

Take the black extension/flexion block paddle. Place the extension side of the paddle into the gap and confirm that the knee is balanced to both varus ad valgus stressing and that the knee extends fully (0o ) and that no residual fixed flexion deformity persists. Ensure that the knee doesn’t hyperextend.

Confirm the overall alignment of the limb by placing the alignment drop rod into the hole closest to the patient and confirm the position of the rod in relation to the patient’s tibia and proximally to their femur.

Remove the pins from the anterior aspect of the distal femur and find the holes made in the distal femur in both the medial and lateral condyles when the original Visionaire block was pinned to the patient. These holes are to be used now for the correctly sized femoral antero-posterior cutting block.

The femoral AP cutting block is applied using the two AP holes previously made through the Visionaire cutting block in the femur. Use the cutting block as sized by the Visionaire plan. Hold this block in place by the two oblique pins as seen in the picture above. Using an angel wing confirm that you won’t notch the anterior femoral cortex especially on the lateral side. Look at the posterior condylar resection and ensure the cuts are as planned on the Visionare schedule.

Once we have confirmed that the correct cutting block is applied to the patient and that no notching of the anterior femoral cortex will occur, excise the anterior condylar remnants using the sagittal saw. I saw in an oblique direction starting with the smaller medial femoral condyle first before removing the lateral femoral condyle. By cutting obliquely in a controlled manner you are less likely to notch. However this should have been confirmed prior to cutting with the Angel wing.

Anterior cut showing the classic “grand piano” sign or “map of Australia” if you are a southern hemisphere surgeon! This represents correct external rotation of the component.

Anterior chamfer cuts made using the sagittal saw through the AP cutting block.

Posterior condylar cut laterally through AP cutting femoral block. Use a Hohmann retractor to protect the lateral structures. Avoid plunging into the back of the knee and damaging neurovascular structures.

Posterior chamfer cuts made through AP cutting femoral block. Ensure you don’t cut into the tibia.

Remove the posterior condylar resected bone with a flat osteotome. To gain increased access to the posterior condylar area ask your assistant to simply push back on the proximal tibia.

Confirm the thickness of the posterior condyle resections and compare this to the Visionaire plan. Measure in millimetres with the patella calliper off the tray.

Remove the posterior osteophytes. An easy way to get to the back of the knee is to have your assistant push hard on the proximal tibia posteriorly, this opens up the posterior aspect of the knee. With a sharp osteotome chisel the posterior osteophytes off both the medial and lateral femoral condyle. Remove the posterior osteophyte remants with a currette and bone nibbler. Where the posterior structures are tight reflect them off the posterior aspect of the femur with an osteotome.

Check the flexion gap is balanced. Ensure that you have the correct side and end of the black paddle, one end is for flexion and one end is for extension and the Genesis 2 has an asymmetric flexion gap built in to the resection and this is built also in to the paddle- therefore you MUST use the correct left or right side for testing the flexion gap. Ensure that the correct side of the paddle is facing upwards, so for a right knee it should say right uppermost. Confirm that the flexion gap is balanced both for varus and valgus strain with the knee bent at 90 degrees. If there is a mismatch between flexion or extension or imbalance in varus/valgus strain – you will need to revisit your cuts to work out where the error is and recut as appropriate.

Apply the alignment drop rod into the hole closest to the tibia. Confirm in flexion that the component sits in the correct alignment with the tibia.

Apply the appropriately sized femoral trial to the femur, this will be predetermined from the Visionaire plan – unless you have changed this when applying the femoral cutting block and identified a discrepancy. Hammer this on confirming that it has seated equally on both sides.

Pin the femoral trial to the distal femur using one or two anterior pins.

Place the box cutting jig into the slots on the anterior aspect of the femoral trial. Use the two screws to secure this to the femoral trial.

To perform the posterior stabilised box cut, the Genesis II system uses a circular end-faced cutter twice in both the superior and inferior aspects of the box. Finish with a square shaped end on cutting chisel box, again placing both in the inferior and superior part of the box.

Use the box shaped chisel to finish the box cuts both superiorly and inferiorly in the box cutting jig. Note this Jig is of the older design a newer jig exists which doesn’t have to be screwed into the trial femoral component.

Remove any soft tissue remnants of the PCL with a Bovey and any loose bone with a curette.

The box cut has now been made and now insert the “cradle” to convert the trial into complete PS design (annotation c). Note the anterior femoral pin has been removed.

Using the appropriately sized tibial trial and in this case a 9mm PS polyethylene insert place this on to the proximal tibia guiding the peg of the insert to go into the notch of the femoral component.

Final seating of trial tibial base plate with 9mm PS polyethylene (yellow).

Confirm that the limb goes in to full extension. Test for varus/valgus stability in extension.

A handle has been applied to the tibial tray, through the handle pass the drop rod to confirm that the alignment of the implant is correct.

Mark your rotation now using the two anterior etched lines on the tibial trial. I use a Bovey to score the bone at this level or a marker pen could be utilised. Note the two pins are still in the tibia. I leave them until this point, if there is any concern with the alignment of tightness of the knee during trialling the pins can be used again if further tibial resection is needed. It is difficult to find these pin holes once the pins have been removed. They won’t impede the operation and can now be removed if you are happy with the joints reconstruction.

Confirm patella tracking with the native patella taking the knee from an extended to a flexed position.

Measure the thickness of the patella. Using the patella calliper to measue with the patella everted. I have everted the patient’s patella here using two Kocher’s one inferiorly and one superiorly to the patella.

Using a sagittal saw resect 9mm of bone off the patella. There is a patella clamp to assist this. However, I find freehand is superior. This is a decision each surgeon should make themselves.

The flat cut surface of the patella is now exposed, size this patella. The sizing is 26, 29, 32, or 35mm patella buttons. Using the appropriate sized patella clamp apply it to cut surface of the patella – aiming to medialise the patella button on the native patella to improve tracking.

Once the clamp is applied to the patella – drill the three lugholes aiming to medialise your patella button in reference to the native patella so that it tracks in the trochlear groove of the implant when the patella is inverted. Remove the Kocher’s once this clamp is applied.

The trial patella button is then applied to the back of the patella. Repeat trialling to confirm that the patella tracks satisfactorily in the trochlear groove.

Identify the two medial and lateral holes made in the proximal tibia from the pinning of the tibial Visionaire cutting jig. These will be utilised to place the tibial tray on the proximal tibia. Just as we did with the femoral cutting block the Visionaire plan assists the surgeon in the rotational alignment of both the femoral and tibial components.

Using the small pin place through the medial aspect of the tibial trial tray, find the medial tibial hole on the tibial plateau. Place the tibial tray flat onto the tibia’s cut surface and seat the pin fully. As the cut surface of the tibia is soft be careful not to make a false pin passage -carefully use the predrilled hole.

With the tibial trial pinned in both the medial and lateral holes. Recheck the alignment with the alignment drop rod. Also see if it correlates to where you think the tray should have gone with your Bovey marks performed on slide 69.

Drill the central keel for the tibial component.

Impact the appropriately sized tibial spine impactor and hammer in to position to finish the tibial keel preparation.

Picture of the proximal tibia once prepared to accept the tibial keel component. The centre of the keel cut here is aligned with the dividing line between the medial/mid-third of the tibial tuberosity.

Lavage the tibia with a pulsatile system and then dry the proximal tibial bone once cleaned.

Suction tube is left down the tibial keel cut, continuing to dry the tibia as cement is applied in a ring doughnut fashion on the proximal tibial plateau.

The Genesis II tibial component. Be careful the tibia is sided in this knee replacement system. The tibia sizes range from 1-8.

Apply a ring of cement around the tibial components undersurface. Using cement on the bone surface and the implant has been shown to improve cementation in total knee replacement compared to cement applied solely to bone or the implant.

Impact the tibia paying close attention to its alignment allowing the tibial keel to find its natural position in the tibial keel cut. Do not force this as in osteoporotic bone you can change the alignment of the tibia. The McDonald is being used here to remove excess cement post-impaction of the tibial component. Ensure the tibial component is seated correctly and evenly.

Pulsatile lavage the femoral bone in preparation for cementation and then dry the bone.

Apply a “horseshoe” of cement over the anterior and distal resections on your femur including the anterior chamfer.

Mounted Genesis II PS femoral component note the screw of the impactor is anterior on the introduction device. The femoral component is sized 1 to 8. A size 9 can be ordered for the largest patients.

Apply cement to the posterior aspect of the entire femoral component. Take care not to use much cement in the posterior condylar area as this will extrude behind the femur and you will not be able to get it out.

Impact the femoral component gently whilst mounted on the femoral impactor (pictured). Switch to the freehand impactor to finally seat the femoral component.

Remove the excess cement from the box and medial and lateral gutters of the femoral component. Ensuring that the femoral component is seated correctly and evenly.

Insert the trail polyethylene insert whilst the knee is flexed.

Extend the leg and hold in extension whilst you lavage the patella.

Apply cement to the back of the patella. Identify the three lug holes on the back of the patella by “poking” a McDonald’s instrument through the cement.

Apply the patella button to the patella by aligning its three pegs into the three predrilled holes. If you are struggling at this point to align the patella correctly use a gentle rotational movement to seat the patella i find this helps to locate the holes.

Whilst the cement is curing. Instill local anaesthetic into the soft tissues. I use 0.1% bupivicaine with adrenaline (volume dependent on the patient’s weight).

Once the cement has cured remove any excess cement with a sharp osteotome, in this picture I am also removing an osteophyte remnant from the lateral side of the implant.

Expose the tibial component. Place the blunt Hohmann posteriorly and the sharp Hohmann retractor laterally and anteriorly. Use a swab to protect the femoral component from scratches. Clean the tibial plateau ensuring no loose material is present.

Insert the definitive polyethylene bearing into the tibial component. Slide it into the tibial components grooves in a posterior direction.

Confirm seating of the polyethylene using the reduction tool. Confirm the polyethylene is correctly seated by observing that it is reduced into the holding mechanism on BOTH the medial and lateral sides. Release the tourniquet at this time once the knee is reduced. Lavage the joint removing any loose bone/cement. Achieve haemostasis using the diathermy.

Reduce the patella over the front of the knee. Repair the medial parapatellar incision. In this picture loop PDS monofilament suture is used.

Close the fat layer with vicryl suture.

The skin is closed with 2/0 quill in two layers one subdermal and one subcutaneously.

Apply glue to finish closure.

The dressing is applied once the glue has dried.