Total Knee Replacement- De Puy Attune implant

Once the re-operative range of motion is recorded, the knee is set up with a side support, footplate and sand bag
Once the set up is complete it is important that there is no limitation to maximal flexion as this is helpful for good visualisation throughout the procedure.
The knee is also assessed for the degree of varus/valgus deformity and whether or not this deformity is correctable (returns to normal with gentle force countering the deformity) or fixed. This will help the surgeon plan any necessary releases in order to reestablish anatomical alignment during surgery.

Draping and tourniquet inflation should not restrict access to the operative fieldThe surgeon should still be able to palpate the malleoli and the anterior edge of tibia through the operation, which is extremely important during tibial preparation to access for rotation and varus/valgus alignment. If the surgeon cannot achieve this assessment accurately once the knee is draped then this will not improve during the operation. In this case the surgeon should re-drape the leg.

The knee is covered in an adhesive anti-bacterial filmIn this case it is clear as the patient is iodine allergic.
Topographic landmarks are established in order to plan the initial incision:
quads tendon
superior pole and medial edge of patella
patellar tendon
tibial tubercle

The initial skin incision is madeTo reduce the risk of pain on kneeling I prefer to start the incision a finger’s breadth medial to the tip of the tibial tubercle, The incision is extended cranially in the midline to between 5-10cm proximal to the superior pole of the patella. A larger knee, with a thicker sub-dermal fat layer will often require a larger incision.
This initial incision is continued in line with the skin incision down through the fat layer onto the fascial layer over lying the patellar tendon (paratenon), the patella and the quads tendon.
It is important to gently elevate this fascial layer and overlying fat as one (to avoid skin necrosis) on the lateral side of the knee. This inelastic layer can tether the patella and make eversion difficult, thus limiting access and view. It is less important and indeed unnecessary on the medial side of the incision.

The deep incision is now made in a continuous manner commencing at the caudal end of the tibial tubercle’s medial edge down to boneContinuing proximally this incision will skim the medial border of the patellar tendon, curving around the medial edge of the patella leaving a 5mm cuff and back into the midline as it extends up the quads tendon, finishing 5-10mm above the superior pole of the patella.

The superior geniculate vessels are often encountered as the incision curves back in to the midline proximally, around the level of the superior poleDiathermy ligation is often necessary.
Note how in this image the lateral fat and fascial layer as been retracted lateral to have a clear view for performing the deep incision.

The proximal femur and tibia are exposed and any osteophytes are removedIt must be remembered that a “medial release” for a fixed varus deformity is tightness created by a combination of bony osteophytes stretching the medial capsule and collateral ligament as well as retraction the the soft tissues themselves. A surgeon can inadvertently over release the medial side of the knee if performing a soft-tissue release before later removing the osteophytes during the bony cuts. Meticulous osteophyte excision can be performed with the use of sharp osteotomes and a bone-nibbler. Care must be taken not to damage the medial collateral ligament (MCL).

The patella is everted and any edge osteophytes can be removedThe condition of the retropatellar cartilage is assessed in order to aid a decision to resurface the patellar or not (the debate on this subject continues to rage and is not covered in this section).
A hohmann retractor is placed on the medial side of the knee deep to the superficial MCL. The medial capsule and tibial periosteal layer is elevated by shape dissection commencing at the tibial joint line and extended distally. If there is still a significant fixed varus deformity then the soft tissue elevation will be more extensive. In some cases it is necessary to elevate some of the distal attachment of the MCL from front to back, check on correction along the way. The superficial MCL has a broad distal attachment ending often as far down as 6cm from the jointline. Therefore it is possible to release the more proximal and anterior fibres of the tendon along the with the tibial periosteum without comprising the ligaments integrity entirely or its ability to heal.
The release is continued, at least at the joint level all the around to the semimembranosus tendon, to a depth of at least 2mm as this portion of the tibia will be excised during tibial resection.

Femoral preparation begins with opening the femoral medullary canal with the starter drillDistal femoral cut
The entry point is established preoperatively on the xray and is the point where the anatomical axis of the femur interrupts the distal femoral articular cortex in the AP and sagittal planes. Generally this is between 5-10mm anterior to the PCL attachment in the roof of the notch on Whiteside’s line (a vertical line running from the deepest point of the trochlear to the roof of the notch, perpendicular to the epicondylar axis).
As a tip to aid direction placing the index finger of the non-drilling hand on the anterior cortex reduces the risk of inadvertently drilling out of the femur proximally.

The distal femoral resection jig is assembled on the back tableDistal femoral cut
It comprises:
an intramedullary rod
distal femoral plate with an adjustable angle (black dial)
distal femoral cutting block with adjustable height (red dial)

An intramedullary rod with the distal cutting block already assembled and attached is slid up the femoral canal until it engages in the isthmusDistal femoral cut
There should be very little wobble in the rod once it is properly inserted.
The flat surface of the distal cutting jig plate is pushed up flush against the distal femoral surface. The cutting block is rested on the anterior cortex of the distal femur and fixed with pins. The depth of distal resection should correspond with the thickness of the distal part of the femoral implant, which is this case is 9mm. However the depth of resection can be increased using the red dial, hence raising the joint-line, in patients with a loss of full extension.

The distal femoral cutting block is pinned in situDistal femoral cut
Whilst the left hand in the image is ensuring that the plate is up firmly against the distal femur, the cutting block is pinned in place.

The rod and jig are removedDistal femoral cut
With the block pinned in place, including an oblique pin to stop the block from rising, the rod and jig can be removed. An angel-wing can be passed through the cutting slop to demonstrate the planned resection if required.

Distal resection is completed using an oscillating sawDistal femoral cut
The hohmann retracts are in place to protect the MCL medially, the lateral retinaculum and patella laterally and to improve the view of the distal femur. Do not saw until the view is clear and these structures are protected.

The cutting block is removedDistal femoral cut
I find it helpful to use the flat surface of this cutting block to press up against the flat surface of the cut distal femur to check that it is level. Any discrepancy can lead to the next femoral cutting jig (champfer block) not sitting flush and misplaced anterior, posterior and champfer cuts.

Next the femur can be sizedFemoral sizing
My preferred method is anterior referencing, however this sizing jig is able to perform both. The posterior lugs of the jig are slid behind and against the posterior condyles of the femur whilst the stylus come to rest anteriorly on the upslope of the lateral rise of the anterior femoral cortex. The resting place of the stylus corresponds with the exit point of the anterior cut and will thus determine with the cut leads to notching or not.
Note how the two pin-holes sit next to the number 5 in this case. This is the planned size of the femoral implant.
Two pins are inserted through the anterior referencing pin holes and the sizing jig is removed leaving the two pins in place (see next image).

Femoral rotation is checked with a choice of reference pointsFemoral sizing
It is vital at this point to check that the two pins in the distal femur are parallel to the epicondylar axis as this determines femoral rotation. This can be achieved by resting the angel wing on the pins and feeling for the medial and lateral epicondyles. An imaginary line between the epicondyles should be parallel to the angel wing. Normally this is achieved by fixing the sizing jig at 3 degrees externally rotated to the lug sitting flush with the posterior condyles (marked as “adjustable rotation” in the image).

The corresponding champfer cutting jig, in this case a size 5, is slid onto the pins and fixed in place, flush to the distal cut with two oblique headed screw-pinsFemoral preparation
(Image shows first headed pin in place medially).

The cuts can be checked using the angel wingFemoral preparation
Proceed in the following order:
anterior femoral cut – avoid notching the anterior cortex
posterior cut – protect MCL, LCL and avoid proceeding too deep as the neurovascular structures are at risk especially with the lateral posterior cut. Good direct vision is key. Often the cut bone fragment will perceivably move when the cut is complete.
anterior champfer
posterior champfer – avoid inadvertent damage to the tibial plateau
The block can then be removed.

The femoral cut fragments are excisedFemoral preparation
Any unresected spurs can be removed with combination of a bone nibbler and a file.

The trochlear groove is prepared using the sized jigTrochlear preparation
This implant requires a deepening of the trochlear groove using a sized frame. The frame can also be used to check bone coverage and adjust the medio-lateral position of the femoral implant. It is fixed in place with stubby headed screw-pins and the excess trochlear bone is easily filed down flush.
The advantage of deepening the groove reduces the anterior pressure on the patella post-implantation with a view to reducing post-op anterior knee pain.
The frame is then removed.

The corresponding femoral trial is then inserted and final medio-lateral adjustments to maximise coverage can be madeFemoral trialling
Note the cut outs in the sides of the trial – this represents the edges of a narrow version of the implant particularly useful as female knees are often narrower than male knees of a similar antero-posterior size.

Patellar tracking is assessed with the femoral jig in situFemoral trialling
The one advantage of completing the femoral preparation ahead of any tibial resection is that at this stage femoral rotation can be assessed fairly accurately by reducing the patella and observing its path throughout a range of motion. Ideally the patella should track with out subluxating or lifting.

The lug holes can be drilled at this stageFemoral trialling
Once the surgeon is absolutely assured that he or she is happy with the rotation, size and medio-lateral (ML) position of the femur the lug-holes can be drilled out through the trial. This will fix the final ML position of the definitive implant.

Good visualisation of the tibial surface is key, with retractors which further to serve structures at riskTIBIAL PREPARATION
Tibial resection
Attention can now turn to proximal tibial resection (if not already performed). A good view again is vital. Retractors protect the medial and lateral structures and a posterior hohmann subluxes the tibial plateau forwards. Having previously prepared the femur, at least with a distal cut, helps improve the view of the back of the tibia, vital to know when to stop the AP cut and minimise the risk of neurovascular damage.
Important landmarks to identify are:
tibial tuberosity
anterior edge of the tibial shaft
mid-malleolar point of the ankle

The tibial cutting jig is assembled on the back tableTibial cut
It consists of:
A 0 degree cutting block (sided left and right)
B posterior slope angle set
C height adjustment screw
D further posterior slope adjustable ratchet
E varus valgus adjustable dial
F ankle clamp

The tibial cutting jig is assembled on the back tableTibial cut
Note how the tibial cutting block is sided, in this case for a left knee. The curve follows the medial edge of the tibial plateau away from the patellar tendon. This is particularly helpful as it minimises impingement on the tendon which tends to push the tray into malrotation. Also the saw can be curved around the slot in the cutting block to cut the antero-lateral tibial plateau. It is removable as illustrated.

The tibial cutting jig is assembled on the back tableTibial cut
All adjustments are by small increments improving accuracy. This image shows the adjustment of the tibial slope which can be achieved with the fixed angle selection at the dial (A) (note in image currently set at 3 degrees) and the ratchet (B). I set the angle to 5 or 7 degrees for cruciate retaining knees at A and parallel to the tibial crest at B. One reason for increasing the slope angle would be a patient with limited flexion. Increasing the posterior slope cut maximise the opportunity to increase post-operative flexion or at least makes the implant a non-limiting factor.

The ankle clamp is place around the ankle and the stylus is placed in the slotTibial cut
The red dial on the top of the stylus can be adjusted to any millimeter increment between 0 and 10mm. I will often choose to take 9mm off the unworn side of the plateau (lateral plateau in a varus knee and vice versa) as this is the minimum thickness of the tibial tray and insert. However if by taking 9mm off the unworn side does not remove a minimum of 2mm of bone off the worn side then I readjust. In this scenario I would elect to set the stylus to 2mm and reference off the deepest point on the worn surface.
At this stage the most important thing is to assess for a height and rotation in the coronal plane.

An oval pinhole in the middle of the cutting block allows a pin to fix rotationTibial cut
Reference point are:
the joint level – using the footprint of the ACL and the PCL sulcus
tibial tuberosity – middle 1/3
With this pin in place the jig is stable enough to now proceed to micro-adjust height, slope and varus/valgus angle.

The varus/valgus angle of the jig is adjusted to match the tibial crest along the length of the tibia and the mid malleolar point at the ankleTibial cut
Preoperative x-rays may caution the surgeon for any tibial bow and must be accounted for.
Once satisfied that height, rotation, posterior slope and varus/valgus angle are optimal the block can be fixed through the pinholes with two AP pins and an oblique pin. The jig is removed leaving the cutting block in situ. (The jig can be left on or reattached for the tibial cut depending on surgeon preference for stability reasons although I have found that the three pins hold the block very stable in this system.)

Check tibial alignmentTibial cut
The handle is attached to the block and two parallel rods are dropped through the holes from top to bottom.

The use of two rods allows assessment with parallaxTibial cut
The reason for using TWO rods is to use parallax to avoid misinterpreting the tibial varus/valgus direction due to malrotation of the viewing point of the surgeon. Note how from this viewing angle two rods are visible, meaning that the rods are not being viewed in parallel.

The use of two rods allows assessment with parallaxTibial cut
By rotating your viewing point (i.e. your head!) and closing one eye the aim is to make the posterior rod disappear behind the anterior rod which can only happen if the rods are being viewed in parallel. It is at this point that the varus/valgus direction can be assessed accurately in relation to the tibial crest and midmalleolar point. It is important to feel for the tibial crest as adiposity can obscure its view.

The handle is removed and the cut is made with a broad oscillating sawTibial cut
As the posterior saw cut is blind one tip is to lay the saw on top of the tibia and cutting block with the cutting edge of the saw at the back of the intended cut and observe the corresponding point on the saw blade with the front of the cutting block. This can reduce the risk of neurovascular damage.
The hohmann retractors act to improve exposure and protect the MCL and lateral structures. By placing the posterior hohmann slightly lateral to the midline not only does it increase direct anterior subluxation of the tibia but it also serves some protection of the popliteal vessels and nerve. Care must be taken not to sever the popliteus tendon or the PCL.
Areas of particular difficulty to cut are the posterior edges, both medially and laterally, and the antero-lateral tibia due to the presence of the patellar tendon. It is obviously preferable to undercut and visit with better visualisation than to be overzealous and cause inadvertent damage.

Once the cut is completed the block can be removed but the two parallel pins should be left in place as a reference for rotation (as it matches exactly the predetermined rotation and therefore the direction of the slope)Tibial cut
The cut tibial plateau is lifted with a broad osteotomy, grasped with a heavy clip and excised. The tip for this is to grasp the medial side and rotate the fragment out as per the image releasing, by sharp dissection under direct vision, in order:
posterior horn medial meniscus
recessing the PCL off the mid-portion’s downslope
posterior horn lateral meniscus
antero-lateral soft-tissue
These attachments are surprisingly consistent.
The cut tibia underside offers a rough measure of the tibial tray size.

The gap-stick in the image is assessing the flexion gap (distance between the posterior femur and proximal tibia)Gap check
It is important now to establish if enough tibia has been resected and if the flexion gap and extension gap are equal and balanced.
Shims of 1mm incremental increasing depth can be attached to the gap-stick until the gap is filled. The balance of the soft tissue is assessed by attempting to open the medial and lateral sides. If there is more opening on one side versus the other the tighter side can be incrementally release and a thicker shim is attached to the gap-stick until the gap is filled and balanced.

The gap-stick in the image is assessing the extension gap (distance between the distal femur and proximal tibia)Gap check
The extension gap is checked next. The same depth shim must fill the extension and the flexion gap in order for the gaps to be balanced. Again varus and valgus stress is applied to ensure the soft tissues are balanced.
If there is a mismatch in the gaps the following options are available:
extension gap tight / flexion gap loose – resect more distal femur
extension gap loose / flexion gap tight – downsize femoral component (this elevates the posterior condyles)
extension gap tight / flexion gap tight – resect more proximal tibia
extension gap loose / flexion gap loose – increase the thickness of the shim

The gap-stick also has holes to allow for long-leg alignment to be check using the drop-rodsAlignment check
Proximally the rod should overlie the hip joint which is midway between anterior-superior iliac crest and the symphysis pubis. Distally the rod should align with the mid-malleolar point.

Tibial sizing with the tibial trial trayTibial sizing and preparation
The tibial tray that covers the cut surface optimally without medial overhang is trialled. The handle should align with the two pins in the anterior tibia as this matches the rotation.
Medial overhang must be avoided as it can irritate the MCL and cause post-operative pain.
Once the correct size is chosen the trial tray is pinned in position.

The keel is prepared with a drill and a keel punchTibial sizing and preparation
The latter can be left in situ by detaching the handle to fix the trial tibial tray for the purposes of trialling.

The femoral trial is put back in and the shim depth that matches the depth used to confirm balance with the gap-stick is added to the tibial insert trial and insertedTrialling
The patella is reduced and the knee is taken through the full range of motion, checking for soft tissue balance. Full extension and full flexion is confirmed. It is always worthwhile considering trialling a number of inserts to confirm the correct feel of balance.

Excision of posterior osteophytes and capsular release as appropriateFinal preparation and washout
Retained posterior femoral osteophytes are a common cause of restricted flexion due to impingement and reduced extension due to tenting of the posterior capsule. It is always advantageous to formally explore the posterior knee using a laminar spreader. This can also be used if posterior field block is used with local anaesthetic.

The cut surfaces are thoroughly irrigated with pulse lavage to reduce blood and fat to a minimum prior to cementingFinal preparation and washout
The surfaces are dried.

The tibia is prepared first with cement applied directly to the cut surfaceImplant cementation
The definitive tibial tray is inserted, pushed into position and impacted. Excess cement is removed.

Cement is applied to the inner surface of the posterior condyles of the femoral component and to the distal and anterior femur cut surfacesImplant cementation
Attention then turns to the femur. The lug-holes are identified by pressing on the cement on the distal femur as seen.

The femoral component is inserted initially by hand to align the lugs with the lug-holesImplant cementation
Deep flexion is required to allow the posterior condyles to engage correctly. The implant can then be gentle pushed on.

Finalisation of femoral insertion at 90 degrees of flexionImplant cementation
Now the knee is brought to 90 degree or less of flexion to allow impaction with a mallet. Reducing the amount of flexion minimise the risk of damaging the posterior condyles of the femoral component on the back of the tibial tray and inadvertent anterior lifting of the tibial tray. Excess cement is removed.

The trial insert is reduced into place whilst the cement curesImplant cementation
The knee can be brought into extension at this stage. Excessive movement should be avoided whilst the cement is curing to stop the implants from rocking.

Definitive tibial insert is impactedImplant cementation
Once the cement has cured the trial insert is carefully removed, avoiding damage to the metal implants. Any final excess cement can be removed, thorough irrigated and any final insert trialling can be performed. The definitive insert is then impacted. Final trialling with the patella reduced is performed.
Thorough irrigation is done and the wound is closed in layers.

Deep closure with absorbable suturesClosure
All suture material is absorbable.
Any potential bleeding vessels can be treated with diathermy. The most common of these encountered is the superior geniculate vessels at the lower end of the quads tendon as it inserts into the superior pole of the patella.
The extensor mechanism is closed – quads tendon, medial retinaculum and patellar tendon edge. I prefer to use interrupted or locked sutures adjacent to the patella as the forces here can be more sheer in a medial-lateral direction as per a lateral patellar dislocation.
Interrupted fat stitches are used dependent on the depth of this layer. A subcuticular suture opposes the skin edges. Skin clips are used as the most superficial layer as these are interrupted, quick and inert. The interrupted nature is vital as it prevents the wound from gaping during knee flexion.

Skin closure with an absorbable suture in subcuticular and clips to skinThe skin is washed and dried.
The wound is dressed with a sterile dressing and wool and crêpe bandage is applied. The tourniquet is released and distal capillary refill is assessed.

AP view

Lateral view