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Preoperative Patient Care
Operative Techniques

Preoperative Plan


Radiographic templating

  • Upload AP knee film with radiographic marker into templating software system
  • Identify the radiographic view, side to be templated, and calibrate the image
  • Determine the AP resection lines for the femur and tibia relative to the anatomic axes
  • the proximal tibial resection is perpendicular to the anatomic axis
  • the distal femoral resection is in 5 degrees of valgus relative to the anatomic axis
  • Measure the distance between the IM cutting guide and the lateral femoral condyle
  • Upload the lateral knee film and calibrate the image
  • Measure the depth of the anterior femoral cut relative to the tip of the anterolateral flange of the distal femur
  • Evaluate for posterior femoral osteophytes
  • Measure the amount of posterior tibial slope


Execute surgical walkthrough

  • Describe steps of the procedure to the attending prior to the case
  • Describe potential complications and steps to avoid them

Room Preparation



Surgical instrumentation

  • Confirm that all necessary surgical instrumentation is on the back table and sterile


Room setup and patient positioning

  • An OR table with removable leg extensions is used
  • The patient is placed in the supine position
  • Secure both arms to well-padded arm boards placed at 90 degrees of abduction
  • A thigh tourniquet is placed as proximal as possible on the operative leg
  • A foot holder plate is placed such that the knee bends to 90 degrees
  • The ipsilateral leg extension is removed
  • The nonoperative leg is padded and secured to the bed with tape
  • An ipsilateral hip bump is placed so that the patella points straight toward the ceiling
  • Secure the patient's torso with a seatbelt attached to the bed
  • A mayo stand is brought in from the head of the bed on the nonoperative side
  • The removable leg extension facilitates surgeon access to the front of the knee


Surgical preparation and draping

  • Cover the mayo stand and each arm with two quarter sheets
  • Isolate the operative extremity with an adhesive impervious drape placed just distal to the tourniquet
  • A stockinette is used to grab the foot from the circulator
  • An adhesive drape with tails is placed over the impervious drape distally
  • The foot is placed into a foot holder and secured with a wrap
  • An adhesive bar drape functions as the upper drape for anesthesia
  • A blue towel with suction, bovie, pulsed lavage, and clamps is opened and secured to the Mayo stand, which is now covered by the upper drape
  • An adhesive drape is used to cover all exposed skin on the operative limb
  • The leg is elevated and the tourniquet is inflated

Medial Parapatellar Approach to the Knee



Identify anatomy and planned incision

  • Mark the medial aspect of the tibial tubercle
  • Mark the medial, lateral, proximal, and distal patellar borders
  • Draw a midline longitudinal incision from 2.5 cm above the patella, through the middle of the patella, and to the medial border of the tibial tubercle


Incision and superficial dissection

  • Create the planned skin incision with the knee flexed
  • this can be performed in extension as well
  • Use bovie electrocautery to perform subcutaneous dissection to the level of the extensor mechanism
  • Develop medial and lateral full-thickness flaps
  • expose the "lateral soft spot"
  • expose the medial patellar border and VMO fibers
  • Assistant retraction facilitates medial and lateral flap development

Arthrotomy and Deep Exposure



Identify anatomic landmarks for medial parapatellar arthrotomy

  • Identify the medial quadriceps tendon, VMO muscle fibers, medial patella, and medial tibial tubercle
  • Mark the planned arthrotomy with bovie electrocautery
  • Place finger at the lateral soft spot and palpate the medial patella and border of the patellar tendon to define arthrotomy


Perform medial parapatellar arthrotomy

  • Perform medial parapatellar arthrotomy with a scalpel along the planned incision
  • to aid in subsequent closure, 5 mm of quadriceps tendon is left attached to the VMO
  • likewise, a 5 mm cuff of retinaculum is left attached to the medial border of the patella
  • care must be taken distally not to incise the patellar tendon or its distal insertion


Perform superficial MCL partial release

  • Using a scalpel, release the anterior horn of the medial meniscus and partially release the superficial MCL fibers directly off of the proximal tibia
  • ensure dissection directly off of bone
  • The extent of release depends on the severity of deformity
  • Varus = greater release
  • Valgus = less release


Expose and prepare the joint space

  • Extend the knee to release fat pad from proximal tibia
  • Flex the knee and place medial and lateral homans
  • Resect the patellar fat pad
  • Release the ACL, PCL, and lateral anterior meniscal horn
  • Homan placement should be under the menisci and directly adjacent to the proximal tibia
  • This improves soft tissue retraction and joint exposure

Create the Extension Gap



Identify proper femoral rotation

  • Place the knee in 90 degrees of flexion
  • Introduce distal femoral intramedullary canal reamer
  • anteromedial corner of intercondylar notch
  • Set femoral rotation with intramedullary rotation guide and mark this with bovie electrocautery
  • When setting femoral rotation, the primary landmark is perpendicular to the mechanical axis of the tibia
  • Secondary checks include Whiteside's line and the transepicondylar axis
  • The goal is to perform femoral cuts parallel to the eventual cut surface of the tibia in order to achieve balanced gaps


Place intramedullary guide and perform anterior femoral rotational cut

  • Insert the intramedullary alignment guide and orient according to the previously marked rotation
  • The anterior cutting guide is placed and secured to the IM guide
  • this should be oriented perpendicular to the mechanical axis of the tibia
  • An oscillating saw is used to make the anterior femoral cut
  • the "grand piano" sign confirms adequate resection
  • A stylus is placed at the anterolateral femoral cortex to determine the amount of anterior resection
  • Take care to avoid femoral notching, especially laterally


Perform distal femoral cut

  • Remove the anterior cutting guide and place the distal femoral cutting guide
  • Secure the distal femoral cutting guide with pins and remove the intramedullary alignment guide
  • Retract the medial and lateral skin flaps with homans to obtain adequate distal femoral exposure
  • An oscillating saw is used to perform the distal femoral cut
  • The desired amount of distal femoral valgus is based off the IM alignment guide
  • As a general guideline after the distal femoral cut, the cancellous bone of the condyles should approach one another
  • If the cancellous bone meets across the middle, the femoral cut may be excessive


Expose the tibia and perform tibial resection

  • Maximally flex the knee and place medial and lateral retractors to maximally expose the joint space
  • A PCL retractor is placed along the posterior tibia and levered to sublux the tibia anteriorly
  • The tibial cutting guide is positioned with an extramedullary alignment rod
  • the alignment rod is oriented from the tibial tubercle to the center of the ankle
  • The depth of resection is set using a stylus and the appropriate tibial slope is set
  • an angel wing stylus can be used to assess the planned resection
  • The alignment rod is removed and an oscillating saw is used to perform the tibial resection
  • A broad, straight osteotome is used to elevate the resected tibia
  • A spiked clamp is applied to allow for manipulation and the resected tibia is stripped from any remaining soft tissue attachments
  • The PCL retractor is critical to sublux the tibia, maximizing exposure
  • Occasionally, particularly tight knees cannot be subluxed and must be carefully cut in situ
  • Avoid cutting the collateral ligaments, the popliteus tendon, and the neurovascular structures of the posterior knee


Evaluate the extension gap

  • Place the extension gap block on the proximal tibia and bring the knee into exension
  • Assess leg alignment, extension gap symmetry, and stability

Create the Flexion Gap



Place the appropriately sized femoral 4-in-1 cutting guide in proper rotation

  • Flex the knee to 90 degrees and insert the flexion gap block
  • Mark the planned posterior femoral condylar resection from the guide
  • Place the appropriate-sized 4-in-1 cutting guide on the distal femur and mark the planned posterior resection
  • Femoral component sizing is determined by the 4-in-1 cutting guide whose posterior cut matches that of the flexion gap block


Perform posterior femoral, anterior femoral, and chamfer cuts

  • Secure the 4-in-1 cutting guide with two threaded pins
  • Use an oscillating saw to perform all femoral cuts, taking care to avoid notching
  • Remove all guides and use an osteotome and rongeur to remove bone from each cut
  • The second anterior femoral cut allows for fine-tuning of femoral component rotation based upon balanced flexion gap


Resect the menisci and remove posterior osteophytes

  • Place femoral intramedullary retractor and open the flexion space
  • Resect the lateral meniscus
  • Resect the medial meniscus
  • Remove posterior femoral osteophytes with a curved osteotome and mallet
  • a curved curette and rongeur can be used to retrieve the osteophytes and any posterior loose bodies
  • Local anesthetic cocktail can be injected into the posterior knee, superficial MCL, and distal femoral periosteum
  • Preserve the LCL and popliteus to avoid lateral laxity, particularly in flexion
  • Preserve the MCL to avoid medial laxity


Prepare the tibia

  • Maximally flex the knee
  • Place medial and lateral retractors
  • Place a wide PCL retractor to bring the tibia forward
  • Perforate sclerotic bone at the tibial surface with a smooth pin to improve cement fixation
  • Secure the appropriate-sized tray to the tibia in proper rotation with 2 headed pins
  • Use a rongeur to remove tibial osteophytes
  • The proper intramedullary guide is attached to the tibial tray and an entry reamer is introduced to the appropriate depth
  • A keel punch effectively maintains the rotation for the final implant
  • Ensure that the selected tibial tray size does not overhang
  • Ensure proper rotation with the center of the tray in line with the tibial tubercle

Trial Components and Confirm Balanced Knee



Place tibial base plate trial

  • The tibial guides are removed and the trial tray is retained
  • The trial polyethylene insert is placed


Place femoral trial component

  • The PCL retractor is removed and the tibia is reduced in flexion to access the distal femur
  • The appropriate-sized femoral trial component is placed and seated with a mallet
  • The medial-to-lateral position is assessed and adjusted as necessary


Confirm balanced extension gap

  • Ensure proper extension gap balancing - the knee should be able to fully extend (indicating no flexion contracture) without hyperextension (indicating a loose extension gap)


Confirm balanced flexion gap

  • The trial components should not extrude in full flexion ("lift off sign" indicates the flexion gap is too tight)


Confirm AP stability

  • Perform manual AP stress testing with the knee in 90 degrees of flexion


Confirm varus/valgus balance

  • Manually assess the varus and valgus stability in full extension (extension gap balance), 30 degrees of flexion, and 90 degrees of flexion (flexion gap balance)


Confirm femoral and tibial implant sizes

  • Once the proper trial component sizes and positions are confirmed, the femoral pegs are drilled from the trial
  • Use the oscillating saw to make the femoral trochlear cut


Prepare the patella

  • Extend the knee
  • Evert the patella, assemble appropriately-sized patellar reamer, and set desired resection depth
  • Remove marginal osteophytes with a rongeur
  • Drill lug holes through the appropriate patellar drill guide
  • The patellar reamer clamp is placed flat against the everted patella to ensure even reaming in all 4 quadrants
  • Position the drill guide preferentially superior and medial on the patella to facilitate proper tracking of the implant

Final Implant Placement


Remove trial implants and prepare the femur and tibia

  • Flex the knee and place retractors medially and laterally
  • Remove the trial poly with a small osteotome
  • Remove trial femur with slotted backslap
  • Irrigate the femur with pulsed lavage, place dry lap and wide PCL retractor
  • Remove the trial tibial tray and pins with wide osteotome


Prepare the tibial surface and cement the final tibial component

  • Irrigate the tibia with pulsed lavage and dry with lap
  • Manually place tibial cement mantle and digitally impact it into the cancellous bone
  • Impact final tibial component and remove excess cement


Place the tibial polyethylene insert

  • Dry the tibial tray with a lap sponge
  • Manually insert the desired polyethylene insert and lock into place with inserter and mallet


Cement the final femoral component

  • Remove the PCL retractor and reduce the tibia
  • Manually place femoral cement mantle and digitally impact into the cancellous bone
  • Use a freer to identify the femoral peg holes
  • Impact final femoral component and remove excess cement


Prepare the patellar surface and cement final patellar component

  • Irrigate the patella with pulsed lavage and dry with lap
  • Place patellar component with cement
  • Place patellar clamp and remove excess cement

Wound Closure


Irrigate and obtain hemostasis once tourniquet is deflated

  • Irrigate the wound and obtain hemostasis with Bovie electrocautery prior to closure


Close joint capsule/arthrotomy

  • Arthrotomy closure is performed with interrupted Vicryl suture and reinforced with running Quill suture
  • Local anesthetic is injected into the joint as well as the subcutaneous tissues


Perform superficial closure

  • Subcutaneous closure is performed with simple interrupted Vicryl suture
  • Subcuticular closure is performed with running Monoderm suture


Dressing is applied

  • Dermabond is placed along incision
  • Steri-strips are applied
  • A pre-fabricated silver dressing is applied
  • Webril and Ace bandages are applied
Postoperative Patient Care
Private Note

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