Total Knee replacement- Vanguard 360 knee replacement (Zimmer-Biomet)

The AP X-ray shows reasonable bone stock but with generalised osteopenia. There was a 12 degree valgus alignment of the distal femur.

The lateral view shows a 7 degree posterior tibial slope and significant patello-femoral arthritis.

The patient has a chlorhexadine 3% preprep in the anaesthetic room with intravenous antibiotics, tranexamic acid and an above knee tourniquet.
There is a lateral support and foot roll allowing the knee to be hyper flexed. The leg in theatre is then prepped and draped and a betadine impregnated adhesive drape is applied.

A midline longitudinal incision is made with a medial para-patella arthrotomy. A 1cm cuff should be left attached to the patella to aid secure closure and proximally the arthrotomy is into the quadriceps tendon 2 cm from the edge of Vastus Medialis muscle. An extensile approach can be used if necessary with a quadriceps snip performed at 60 degrees extending into the quadriceps tendon.

The intramedullary rod is the inserted avoiding penetrating the anterior femoral cortex.

The femur is usually prepared first. The IM drill is utilized to penetrate the cortex and dense cancellous bone to a depth of approximately one to two inches. The canal entry location is placed 1cm above the insertion of the posterior cruciate ligament and slightly medial in the intercondylar notch.

Set the adjustable distal femoral resection guide to 5 degrees and a distal femoral resection depth of 9mm. The block is then fixed with three drill pins and the alignment rod removed. It is essential the the distal femoral resection is performed at 5 degrees to coincide with the fixed angle stem on the femoral component.

Perform the distal bone resection using an oscillating saw. Medial and lateral bone lever retractors are placed in front of the collateral ligaments to prevent inadvertent damage. The distal cutting slit is used, the proximal slit on the cutting block will add 3mm to the distal femoral cut and can be used in cases with severe fixed flexion.

The trans epicondylar axis is marked and Whitesides line to help fix the rotation of the femoral component. Whitesides line is drawn from the femoral notch to the centre of the trochlea. Whitsides line should be perpendicular to the epiconylar axis. The epicondyles can be difficult to identify, but the lateral epicondyle can be found by identifying the attachment of the lateral collateral ligament. The medial epicondyle is found by removing overlying synovium and feeling for the widest part of the femoral condyle. This is best felt from above

The A/P sizer is placed flat against the resected distal surface with the feet in contact with the posterior condyles of the femur. Aim for 3 degrees of external rotation but adjust for femoral dysplasia and use the epicondylar axis line. Place the telescoping stylus slightly lateral to the midline on the anterior cortex. The femoral component size can now be read from the central scale. Drill the holes in the guide using the collared drill pins. The guid should sit flat against the distal femoral cut. If it lifts up try flexing the knee to 110 degrees, also any remaining meniscus can get in the way and may need to be removed at this stage.

Choose the slotted femoral 4 in 1 guide which matches the selected size on the adjustable A/P sizing instrument, and place it into the holes drilled into the distal femur. Attach the handles into the sides of the contour block and make sure the contour guide is sitting flush against the flat area of the distal femur.Once the block position is satisfactory, resect the anterior and posterior bone, and the anterior and posterior chamfers. Make sure bone spike retractors are placed to prevent collateral ligament damage.

Attention is then moved to the tibia and a Hohmann retractor is used to sublux the tibia forward. The tip of the retractor should be against the posterior tibial cortex to avoid damage to the popliteal vessels.

Fully flex the knee and locate the center of the tibial plateau. Center the drill and create an entry hole with the 9 mm drill. The entry point is at the tibial spine which should be removed with a bone nibbles to aid insertion. Progressively ream the tibial medullary canal with the fluted cylindrical reamers to the proper depth until cortical chatter is obtained. When reaming is finished, engage the fins of the reamer into the bone several millimeters by tapping the end of the reamer with a mallet.

Attach the appropriate side specific tibial resection block to the IM tibial resection guide by the screw attachment.Place the IM tibial resection guide over the proximal end of the reamer and lower it until the stylus contacts the least affected tibial condyle aiming to resect 10mm off the unaffected side. Move the cutting block against the anterior tibia by pushing in the silver button on the resector body.Fix the cutting block in place with three drill pins.

Remove the tibial resection guide, alignment tower and rod, leaving the tibial resection block in place.

Resect the proximal tibia and remove.

Select a tibial sled size that provides the best tibial plateau coverage.Tibial sled coins allow trial stem attachments to evaluate sled position with a stem. Starting with a 0 mm coin (no stem offset), thread a trial stem corresponding to the tibial reaming diameter and depth to the tibial sled coin by rotating the stem.The stem offset can be rotated for exact tibial placement and is available in 2.5 mm, 5 mm and 7.5 mm offset magnitudes. To add tibial implant rotational stability, small or large cruciate wings can be added to the modular boss on the bottom of the tibial tray.

The femoral trial is positioned and the femoral canal is reamed.Progressively ream using the cylindrical fluted reamers until cortical chatter is obtained.The modular boss allows a trial stem to be attached to the femoral trial without resecting the box. Depending on the magnitude of offset required for adequate coverage, select the appropriate left or right offset modular boss: 2.5 mm, 5.0 mm or 7.5 mm.

The intercondylar box resection is performed with the cut out trial in situ. Resect along each interior edge of the trial with a reciprocating or oscillating saw. Make wall cuts first to the depth of the box, then proceed with the vertical cut utilizing a small oscillating blade or a reciprocating blade until intercondylar bone is removed.

Secure a left or right specific reamer housing to the cut-through femoral trial.Ream through the offset reamer bushing with either the neutral or offset reamer until the reamer stop hits the reamer bushing.

The trial stem is attached to the box bossing then secure the modular box to the cut-through femoral trial.

The trial prosthesis is assembled. In this case no offset was required and an SSK insert articulation was chosen.

The trial tibial component is inserted first then impact the femur.

The trial was done using a 10mm SSK insert. FROM was obtained with good collateral stability and patella tracking.

The modular tibial prosthesis is assembled remembering to attach the fin before the stem and to remove the screw in the stem.

The femoral prosthesis is assembled, care should be taken inserting the femoral screw as this can cross thread.

Hardinge cement restrictors are inserted and the bone washed with pulse lavage. Ribbon gauze is inserted into the canals to keep them dry for cementation.

Palacos cement is used with a pressurised cement gun. Use separate mixes for each component to allow for adequate working time.

The tibial component is inserted first.

The femur is cemented using a second mix of cement.

In this case a 10mm insert was used, fixed to the tibia with a clip.

Finally range of movement, stability and patella tracking is checked.

The arthrotomy is closed using a PDS suture followed by a layered closure with clips to skin.

The postoperative AP xray shows a well balanced and aligned prosthesis. The canals are not fully filled but with long cemented stems there is adequate fixation.

The lateral view shows a well aligned prosthesis that is sitting well.