///

Total Knee replacement- Zimmer Biomet Nexgen rotating hinge replacement

    Overview

    Learn the Total Knee replacement: Zimmer Biomet Nexgen rotating hinge replacement surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Total Knee replacement: Zimmer Biomet Nexgen rotating hinge replacement surgical procedure.
    Learn the Rotating Hinge Total Knee Replacement- Nexgen Rotating Hinge (RH) Knee (Zimmer) surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of this RH knee for medial collateral ligament deficiency with valgus deformity.
    The NexGen RH Knee features a bone conserving modular hinge design that addresses key issues related to many conventional rotating hinge knee designs. The hinge system utilizes the same stems, cones, patellas, and both Trabecular Metal™ and Precoat augments as the NexGen LCCK Constrained Knee System. Bone cuts for the RH Knee system are similar to those of the LCCK system. This feature allows bone conservation as well as easy intra-operative conversions from LCCK.
    In many conventional rotating hinge knee designs, the hinge mechanism bears the majority of the compressive load until full extension is achieved. Designs that have the centre of rotation located posteriorly can cause “booking” of the joint, which may result in stress on the cement interfaces or accelerated polyethylene bearing wear in the hinge.
    The NexGen RH Knee addresses these concerns as the RH Knee femoral component and articular surfaces are designed to maintain centralized contact throughout ROM (from -3° of hyperextension to 120°) resulting in 95% condylar loading through the tibial condyles.
    This is the case of a 91 year old lady who had developed tricompartmental osteoarthritis and medial collateral ligament deficiency leading to valgus deformity. In such case a surgeon may choose to use an implant with less constraint such as a posterior stabilised design, however these can still develop instability and require revision to a hinged knee.
    In this technique I will focus on the arthroplasty technique using the Nexgen RH Knee.
    The important points to assess preoperatively include attention to instability symptoms in the history and evidence of valgus deformity clinically and radiographically in the coronal plane. Examination often reveals frank medial collateral ligament deficiency and therefore in this situation the surgeon should have a low threshold for proceeding to full constraint with a rotating hinge design.
    OrthOracle readers will also find the following techniques of interest:
    Revision total Knee Replacement- Legion Rotating Hinge Knee ( Smith and Nephew)
    Revision total Knee Replacement: Legion CCK (Smith and Nephew)
    Total knee replacement Genesis 2 (PS) with bi-convex patella (Smith and Nephew)
    Total knee replacement: Vanguard XP cruciate retaining (Zimmer-Biomet)
    Total Knee replacement: Vanguard 360 knee replacement (Zimmer-Biomet)

    Indications

    INDICATIONS
    The main indication for a rotating hinge knee replacement as a primary implant is end stage osteoarthritis with medial collateral ligament deficiency and valgus deformity.
    A further indication is in the trauma setting where an older patient has a comminuted intra-articular fracture, usually involving the tibial plateau(s) which is deemed not suitable for reconstruction.
    Finally deformity and pain due to rheumatoid arthritis is another indication although this situation is thankfully becoming rare due to effective early disease control via systemic medication.
    SYMPTOMS & EXAMINATION
    Patients with osteoarthritis along with valgus deformity and MCL incompetency will typically be in constant pain made worse by activity and they may have night pain that keeps them awake. The patient may have recurrent knee effusions. Patients may complain of instability- describing the knee giving way and causing them to stumble and they may have had several falls due to this.
    On examination the findings are often obvious valgus deformity which can be exaggerated on passive flexion and valgus stress on the knee. Placing valgus stress on the knee is important to test the competency of the MCL. The valgus deformity may be unimpressive but if the MCL is incompetent then this is an indication for a hinged knee replacement. It is also important to document whether a fixed flexion deformity is present or not. In this case it was not present, however is it was, then the standard distal femoral resection of 10mm would be increased to 12mm along with release of the posterior capsule.
    IMAGING
    Standard AP and lateral radiographs may be sufficient, however a skyline view of the patella may demonstrate hypoplasia of the lateral femoral condyle and long leg radiographs may be useful to assess the degree of deformity in the coronal plane.
    ALTERNATIVE OPERATIVE TREATMENT
    In younger patients with valgus deformity and medial collateral ligament deficiency, osteotomy and ligament reconstruction can be considered. In older patients, a posterior stabilised implant with a substantially sized post can be used but failures of these with instability have certainly be documented.
    NON-OPERATIVE MANAGEMENT
    Once osteoarthritis is established treatment is limited to conservative measures or joint replacement depending on the patient’s level of symptoms. A hinged knee brace may help and indeed during the coronavirus pandemic several patients at our centre had reasonable symptom control using these while awaiting routine elective surgery to resume.
    CONTRAINDICATIONS
    Active infection such as a symptomatic UTI, open skin ulcers or upper respiratory tract infection, is a significant contra-indication to knee arthroplasty.
    Some disease – modifying immunosuppressants should be stopped for 1 dosing cycle. In general it is the Biological agents which need stopping whereas Methotrexate and Sulphasalazine may be continued.

    Setup

    A suitably anaesthetised patient is positioned on the operating table in the anaesthetic room. We use both spinal with or without sedation or general anaesthetic depending upon patient and anaesthetist preference. An adductor canal nerve block is often used; this does not prevent the use of local infiltration techniques, but the dose calculations need to be worked out to prevent exceeding the total local anaesthetic doses for the patient. Cefuroxime 1.5g i.v. and Tranexamic acid 1g i.v. are administered. While to patient is in the anaesthetic room, a tourniquet is placed high on the thigh and a suitable exclusion drape applied to prevent seepage of preparation liquid under the tourniquet. A side support and a large sandbag is used to rest the foot on when the knee is flexed to 90 degrees or more. I use a 2% Chlorhexidine spray in the anaesthetic room on the whole of the exposed leg and then leave it to evaporate.
    The table is then brought through into the operating room and carefully placed within the laminar flow. The aim is to have the knee as central but also ensuring all of the operative trays can be setup within the laminar flow area. Formal surgical preparation with Alcoholic Betadine is then used followed by standard limb exclusion draping, ensuring that hyperflexion of the knee would be possible without pulling the drapes up from the floor.

    Operation – 1

    The photograph demonstrates valgus deformity in both knees. On examination the left knee was found to have MCL incompetency.

    The pre-operative radiographs demonstrate valgus deformity (13 degrees) on the AP view.
    This is not a major deformity however because the patient has clinical MCL incompetency, a hinged knee is indicated.

    The lateral view demonstrates evidence of patellofemoral osteoarthritis. During the operation, the patella should be everted and the state of the articular cartilage in the trochlear groove and the patella should be inspected.
    I have a low threshold for resurfacing the patella- if the patient complains of anterior knee pain post-operatively then as long as the patella is tracking well there is usually no indication to intervene surgically.

    The knee is prepared using Alcoholic Betadine which is allowed to dry prior to application of the drapes.
    Ensure that pooling of the alcohol based preparation is avoided. (NICE guidelines : Surgical site infections, prevention and treatment CG74). An Iodophor-impregnated drape is used unless the patient has an iodine allergy.

    Medial parapatellar approach to the kneeTopographic landmarks are established in order to plan the initial incision:
    quads tendon
    superior pole and medial edge of patella
    patellar tendon
    tibial tubercle
    To 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.

    Fasciocutaneous flaps are raised medially and laterally. It is important to gently elevate the fascial layer and overlying fat as one (to avoid skin necrosis) particularly 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 on the medial side of the incision.
    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.
    The patellar retinaculum needs to be visualised medially and laterally to facilitate eversion of the patella and for the subsequent resurfacing. Excise any prepatella bursa if inflamed.

    The patellar tendon insertion needs to be visualised to facilitate an accurate arthrotomy. Identify the natural rolled edge of the patella tendon medially (annotated with the ‘*’). 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.

    With the knee in the flexed position, perform the arthrotomy from 1–2 cm above the superior pole of the patella, extending to the level of the tibial tubercle.The superior geniculate vessels are often encountered as the incision curves back in to the midline proximally, around the level of the superior pole- diathermy is sufficient to achieve haemostasis. The patella is then 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. In some cases, 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.
    In this case the patella was everted and the condition of the retropatellar cartilage 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). I have a low threshold for resurfacing the patella simply because doing this a a separate procedure at a later date counts as a revision and can significantly increase a surgeon’s revision rate on the National Joint Registry.

    The fat pad is excised to ensure adequate visualisation of the tibial spines and lateral tibial plateau.This also improve mobilisation of the patella. The ACL is excised from the femoral notch and in this case I also proceed to move the PCL fibres releasing them off the femur as I am performing a hinged knee replacement. It is important to be careful not to plunge into the deep aspects of the notch as you risk damage to the popliteal blood vessels.

    Expose the tibia for resection by dislocating the tibia anteriorly.This can be performed by levering on the tibia posteriorly with a Hohmann 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. Prior to inserting the lateral retractor, it is worth excising any residual fat pad, capsule and lateral meniscus which can get in the way of placing it.

    Drill a starting hole with the 8mm intramedullary step drill centered mediolaterally over the midpoint of the isthmus of the tibial canal.For this system, intramedullary tibial preparation to site the cutting block is recommended. In the AP plane, the drill should start in between the tibial spines.

    Beginning with the 9mm intramedullary reamer, the canal is progressively hand reamed until cortical contact is achieved.Ream at least 1cm greater than the overall length of the selected components, burying the cutting flutes beneath the bone surface. In this case the implant stem length is 90mm so reaming continued to 12mm where cortical contact was achieved and to a length of 110mm. This reamer is left in place for the spike arm to be inserted.

    The spike arm with the tibial cutting block is placed over the reamer.Align the vertical arm (annotated ‘$’) with the tibial tuberosity and crest which will ensure that the cutting block is in the appropriate rotation and this will also help site it onto the tibia.

    The long spike (annotated ‘£’) is engaged first to allow the block to be placed in the appropriate position with due regard to rotation. Note the short spike is not yet engaged (annotated ‘&’). The cutting block has a 0 degree slope and therefore it is a case of manuevering it into a position where the oscillating saw will have optimal access to the tibia. Note the boom (annotated ‘%’) has an attachment annotated ‘Z’ for a slap hammer to facilitate removal. The nut annotated ‘Y’ allows the arm with the cutting block (annotated ‘R’) to be secured when the height has been set using the circular nut ‘X’.

    The short spike is engaged and attention can be turned to setting the height of the block.

    I minimum of 12mm needs to be resected from the tibia to accommodate the polyethylene insert. The stylus has two tabs- 2mm and 10mm. The 10mm tab is annotated ‘A’.

    This image shows the stylus close up with the tab on the right marked with 10mm. This tab should be inserted into the tibial cutting block slot.

    The 10mm tab is engaged into the cutting block slot and the stylus placed onto the medial plateau- annotated ‘S’.

    The block is pinned in place through the holes marked with a ‘0’

    The nut is loosened from the boom.

    A slap hammer is used to disengage the the spike arm.

    The spike arm is disengaged.

    The T-handle is used to remove the reamer.

    The cutting block is moved down 2mm and then the oscillating saw used to perform the tibial cut, removing a thickness of 12mm.

    Operation – 2

    The cutting block is removed.

    A Lane’s tissue forceps is used to grasp the tibial plateau to facilitate removal.

    The tibial plateau is inspected demonstrating maximal wear on the lateral aspect, annotated ‘B’.

    The plateau can be used to size the tibial tray. The tray should be a bit smaller than the plateau itself to account for the osteophytes. In this case it is size 2.

    This image shows the tibial preparation tray close up with the handle attached. The slot for the drop rod is annotated ‘G’.

    The size 2 tray is placed on the tibial surface. An alignment rod can be placed through the slot in the handle.

    The alignment rod proximally should be parallel with the tibial tuberosity and crest. Distally it should be at the centre of the ankle.

    The tray is pinned in place.

    The tibial stem base drill bushing for the conical drill is to be inserted into the tibial preparation tray.

    The tibial stem base drill bushing is inserted- annotated ‘C’. The conical drill is used to make the required hole for the tibial stem.

    The hole is drilled into the tibia using the conical drill until the mark on the shaft lines up with the top of the bushing.

    This image shows the size 1/2 broach for the tibial fins ready to be connected to the impactor.

    The the size 2 broach is attached to the impactor.

    The broach is impacted to the depth mark on the impactor. The broach has a built in stop to prevent over impaction.

    These images show the size 2 tibial trial along with the relevant trial insert. There is a screw hole in the tibial trial (top left image) for an inserter to attach to. Note the hole in the insert (image on the top right). This hole is where the bolt for the hinge mechanism inserts.

    The size 2 trial tibial component is inserted.

    An antero-posterior gauge is used to estimate the required size of the femur.In this case it is ‘C’.

    The 8mm intramedullary step drill is used to drill a starting hole in the centre of the patellar sulcus.

    Beginning with the 9mm Intramedullary hand reamer, the femoral canal is progressively
    reamed the femoral canal until cortical contact is made. In this case contact was at 15mm and the length was 170mm to accommodate a 150mm stem.

    This image shows the the femoral component stem base which is 18mm in diameter. In most cases the femoral canal will be reamed to a diameter of less than 18mm. In this case the femoral canal was reamed up to 15mm. Then in order to accommodate the stem base, the first 70mm of the canal must be further reamed to 18mm.

    The 15mm reamer is reinserted into the femur so that the jig with the distal femoral cutting block can be placed onto it.

    Attach the Plus 1mm Cut Block to the 6° valgus distal femoral guide. The Plus 1mm Cut Block is approximately 2mm in thickness and provides approximately 10mm of bone removal which was adequate for this case because the patient did not have a fixed flexion deformity.

    The top left image shows the block is LCCK 6 degrees left. Once this is placed onto the reamer, the distal cutting block is attached to it through a couple of slots , which is shown assembled in the bottom left and large right images.

    The distal femoral cutting guide is placed over the in-situ intramedullary femoral reamer.

    The distal femoral cutting block A is attached to the guide B.

    Operation – 3

    The block is pinned in place. Note- the Plus 1mm Cut Block is approximately 2mm in thickness and provides approximately 10mm of bone removal.

    An angel’s wing can be used to check the resection level. The short arm of the angel’s wing is inserted into the cutting block slot and the long arm indicates the level of the cut. In this case the long arm shows that there will be a few millimetres of bone removed from the lateral femoral condyle, annotated ‘F’. If the patient has a fixed flexion deformity, the cutting block can be moved so that an additional 2mm or 4mm of bone is removed.

    A cross pin A is inserted to stabilise the cutting block.

    The reamer rod is removed and the oscillating saw used to perform the distal femoral cut.

    The pins and block are removed.

    These images show the LCCK stem base centraliser and femoral cutting block.
    The image on the left shows the orientation for a left knee and in the middle for a right knee. The stem base centraliser can be inserted into the canal first and then the cutting block slotted onto it (see the next set of images).

    These images demonstrate how the stem base centraliser and femoral cutting block can be put together.
    The centraliser can be partially inserted into the canal and then the cutting block attached to it. The rotation can then be checked (pin holes should line up with the epicondylar axis) before pinning the block in place.

    The stem base centraliser is inserted into the canal.

    The femoral cutting block is engaged onto the centraliser and rotation set by aligning the pin holes with the epicondylar axis. Note handles have been attached to the cutting block to allow for fine adjustment of the rotation.

    The block is pinned in place initially through the slotted holes which allows the block to be moved a few millimetres medially or laterally for optimal placement.

    Cross pins are inserted to stabilise the block.

    These images demonstrate how the cutting guide for the anterior femoral cut slots into the LCCK femoral cutting block.

    A guide for the anterior femoral cut is engaged into the LCCK cutting block and the centraliser removed.

    The anterior and posterior cuts are performed.

    When the LCCK femoral cuts are complete, the block is removed and the centraliser used again to apply the RHK femoral cutting block as demonstrated by these images.

    The block is exchanged for the RHK block to perform the chamfer and box cuts. Note the centraliser is used again to ensure appropriate positioning of the block.

    Cross pins as well as headed pins are recommended to ensure maximum stability.

    The centraliser is removed using the slap hammer.

    The chamfer cuts are performed with the oscillating saw.

    The box cut is performed with an oscillating narrow blade saw.

    The block is removed demonstrating the box.

    A broad osteotome is used to remove the posterior femoral fragments.

    The posterior capsule is infiltrated with 50ml 0.125% Chirocaine.

    The femoral trial is assembled by attaching the modular box (annotated ‘R’) to the body. The large black arrow on the image on the right demonstrates the modular box in the correct place.

    The stem is then simply screwed into the base.

    Operation – 4

    The size C femoral trial is inserted onto the femur.

    The minimum trial polyethylene of 12mm has been inserted.

    The trial hinge pin is inserted.

    The trial hinge pin is tightened with the Hex driver.

    The trial components are now articulated.

    There is hyperextension present which is too excessive.

    The insert is changed to 14mm. Note the maximum thickness available is 26mm.

    The extension is acceptable at 0 degrees. Note if the extension gap is tight, then remove additional bone from the tibia. The flexion gap should also be assessed. If it is tight, consider downsizing the femur. If it is loose, consider increasing the size of insert. Alternatively the femur can be offset posteriorly (using an offset stem adpater) to tightened the flexion gap, particularly if a thicker insert causes the extension gap to become too tight.

    Patellar preparationSoft tissues are excised to clearly visualise the edges of the patella.

    A Lane’s forceps is used to stabilise the patella for a freehand cut with the oscillating saw. A minimum of 11mm of bone must remain. In this case 12mm were remaining.

    This image shows the patella sizing keys- the range is 26mm to 41mm.

    I prefer to cut freehand but there is a clamp for cutting the patella as shown in these images.

    These images show the patellar clamp and attachments. On the top left is the cutting guide for the drill and the top right the pressuriser for cementation of the definitive button.

    The patella is sized using the sizing keys- 32mm in this case.

    The patellar clamp is placed with the 32mm block to drill 3x holes. The orientation of the holes is not important- the button is symmetrical.

    The trial button is placed.

    A trial is performed with good tracking throughout the range of movement.

    Preparation for implantation of the definitive componentsThe bone surfaces are meticulously washed and dried.

    A Hardinge restrictor is inserted into the tibial canal. Note in this case cement was inserted into the canals but this is at the discretion of the surgeon- the femoral and tibial bone surfaces must be cemented though.

    A Hardinge restrictor is inserted into the femoral canal.

    A swab is placed to keep the surfaces dry.

    The femoral component is assembled. Note the stem is impacted into the base. There are grub screws at either side of the stem base, annotated ‘D’.

    This is an image of the twist off screwdriver. It is used to tighten the grub screws which secure the stem to femoral implant body. The handle will break off at the narrow section annotated ‘@’ when sufficient force has been applied.

    Twist off Allen keys are used to tighten the grub screws into the stem base.

    Operation – 5

    The components are ready for implantation. Note the trial insert (annotated ‘E’) is used while the cement is setting- this is too avoid excessive motion whilst the cement is setting.

    A double mix of Palacos G cement is inserted into the tibial canal and the surfaces.

    The definitive component is impacted in place.

    Excess cement is removed and the trial insert placed.

    A further double mix of Palacos G cemented is inserted into the femoral canal.

    Cement is placed onto the femoral surfaces.

    The femoral component is inserted. Note it is important to remove excess cement as it extrudes from the canal before the implant is fully seated because it can overflow into the back of the hinge.

    Excess cement is removed with particular attention to the hinge.

    The cemented is allowed to set before the definitive polyethylene insert is placed.

    The hinge is engaged.

    The hinge pin is inserted and tightened with the Hex driver.

    This close up image shows that the maximum torque that can be applied is 130 lb/in. The technique guide recommends at least 95 lb/in which is the dot mark next to the maximum.

    The torque wrench is used to torque the hinge pin to 95 in-lbs.

    Palacos G cement is placed onto the patella and the definitive button clamped in place.

    Excess cement is removed and the cement is allowed to set.

    A final check reveals good range of movement of 0-130 degrees and satisfactory patellar tracking.

    With the knee extended, a number 2 Vicryl suture is used to repair the superior-medial corner of the patellar retinaculum. Further interrupted sutures are placed inferiorly to repair the patellar tendon.

    The knee is flexed up and further interrupted sutures used to repair the retinaculum and quadriceps tendon.

    Subcutaneous tissues are closed with 2.0 Vicryl.

    A subcuticular suture with 3.0 Moncryl is used for skin.

    Longitudinal steristrips are applied.

    A Mepilex dressing is placed.

    Post-operative AP x-ray show a well balanced and aligned prosthesis. In particular the tibial component is well sized with no overhang medially or laterally.

    The post-operative lateral view shows good cementation of the femoral, tibial and patellar components with no cement extrusion.

    Post Operative

    Full weight bearing as soon as possible
    2x further doses of i.v. Cefuroxime 750mg
    Foot pumps as an in patient
    Low Molecular Weight Heparin for 10 days.
    Plain radiographs usually day 1 post-operatively
    Reduce the bandage at 24 hours, but leave the surgical wound dressing untouched if still dry for 2 weeks.
    Discharge home once safe – usually 2-4 days
    The patient simply removes the dressing at 2 weeks with back up from the district nurse if there are any concerns
    Review in the out-patient department at 6 weeks to ensure that the patient is achieving a good range of movement (0-90 degrees), then 12 months if all well.

    Recommended Reading

    Here are a few papers that will provide a starting point and some information that will give you a “ballpark” overview. We strongly suggest that you search out & read the full text versions.
    Mid-term results of rotating hinge knee prostheses. Rajgopal A, Vasdev A, Chidgupkar AS, Dahiya V, Tyagi VC. Acta Orthop Belg. 2012 Feb;78(1):61-7.
    This paper reports the results of 46 rotating hinge knee replacements in complex primary and revision situations. The clinical outcomes were satisfactory at the average follow-up which was 62 months.
    Good mid-term outcome of the rotating hinge knee in primary total knee arthroplasty – Results of a single center cohort of 106 knees with a median follow-up of 6.3 years. Hintze JV, Niemeläinen M, Sintonen H, Nieminen J, Eskelinen A. Knee. 2021 Jan;28:273-281.
    This more recent paper reports on 106 rotating hinge knees implanted as the primary prosthesis. The 10 year survival of the implants was 91.6%, with no radiographic evidence of loosening in the unrevised group.
    Incidence and Risk Factors for Peripheral Nerve Injury After 383,000 Total Knee Arthroplasties Using a New York State Database (SPARCS). Christ AB, Chiu YF, Joseph A, Westrich GH, Lyman S. J Arthroplasty. 2019 Oct;34(10):2473-2478.
    There is a concern regarding injury to the common peroneal nerve following correction of severe valgus deformity during primary arthroplasty. This paper identifies the risk factors associated with nerve injury from a database with a huge number of patients. It confirms that valgus deformity statistically significantly increases the risk of injury. Pre-existing spinal conditions was also a significant risk factor. The presence of both increased the risk even further. Therefore when assessing a patient with valgus deformity, it is important to identify the presence of any spinal condition and explain the additional risk of nerve injury to the patient.

    Reference

    • orthoracle.com

    Tags:

    You might be interested in

    Dark mode powered by Night Eye