Updated: 1/30/2019

TKA - Varus Knee with Anterior Referencing and Gap Balancing Technique

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Questions
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Techniques
3

Preoperative Patient Care

A

Basic Preoperative Outpatient Evaluation and Management

1

Obtain focused history and performs focused exam

  • Identify medical issues that may impact surgical care
  • Knee specific exam should include assessment of soft tissues, range of motion, laxity, and distal neurovascular exam

2

Interprets basic imaging studies (radiographs)

  • Understands Radiographic views of the arthritic knee
  • weight-bearing AP
  • sunrise view
  • Identifies normal anatomic landmarks of the kneee
  • Identifies pathologic findings of the arthritic knee

3

Prescribes and manages nonoperative treatment

  • NSAIDs
  • Physical therapy
  • Assistive devices
  • Injections

4

Makes informed decision to proceed with operative treatment

  • Documents failure of non-operative management
  • Describes accepted indications and contraindications for surgical intervention

5

Provides post-operative management and rehabilitation

  • Postop: 2-3 week postoperative visit
  • wound check
  • remove sutures/staples
  • check radiographs
  • continue physical therapy
  • diagnose and management of early complications
  • Postop: 3 month postoperative visit
  • check radiographs
  • diagnosis and management of early/late complications
  • Postop: 1 year postoperative visit
  • check radiographs
  • diagnosis and management of late complications
B

Advanced Evaluation and Management

1

Appropriately orders and interprets advanced imaging studies

  • Advanced radiographic views, MRI, CT, nuclear medicine imaging, etc.

2

Appropriately recommends surgical intervention

3

Modifies and adjusts post-operative treatment plan as needed

C

Preoperative H & P

1

Obtains history and performs physical exam

  • Identify medical issues that may impact surgical care
  • Knee specific exam should include assessment of soft tissues, range of motion, laxity, and distal neurovascular exam

2

Order basic imaging studies

  • Multiplanar radiographs of the knee, preferably weight bearing
  • 3-foot standing films for leg alignment (optional)

3

Perform operative consent

  • Describe complications of surgery
  • infections
  • thromboembolic events
  • peri-prosthetic fracture
  • neurovascular compromise
  • malalignment
  • patellar maltracking

Operative Techniques

E

Preoperative Plan

1

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

2

Execute surgical walkthrough

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

Room Preparation

P

1

Surgical instrumentation

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

2

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
Pearls
  • The removable leg extension facilitates surgeon access to the front of the knee

3

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
G

Medial Parapatellar Approach to the Knee

P

1

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

2

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
Pearls
  • Assistant retraction facilitates medial and lateral flap development
H

Arthrotomy and Deep Exposure

P

1

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
Pearls
  • Place finger at the lateral soft spot and palpate the medial patella and border of the patellar tendon to define arthrotomy

2

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

3

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
Pearls
  • The extent of release depends on the severity of deformity
  • Varus = greater release
  • Valgus = less release

4

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
Pearls
  • Homan placement should be under the menisci and directly adjacent to the proximal tibia
  • This improves soft tissue retraction and joint exposure
I

Create the Extension Gap

P
P

1

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
Pearls
  • 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

2

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
Pearls
  • A stylus is placed at the anterolateral femoral cortex to determine the amount of anterior resection
Pitfalls
  • Take care to avoid femoral notching, especially laterally

3

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
Pearls
  • 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

4

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
Pearls
  • 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
Pitfalls
  • Avoid cutting the collateral ligaments, the popliteus tendon, and the neurovascular structures of the posterior knee

5

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
J

Create the Flexion Gap

P

1

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
Pearls
  • Femoral component sizing is determined by the 4-in-1 cutting guide whose posterior cut matches that of the flexion gap block

2

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
Pearls
  • The second anterior femoral cut allows for fine-tuning of femoral component rotation based upon balanced flexion gap

3

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
Pearls
  • Preserve the LCL and popliteus to avoid lateral laxity, particularly in flexion
  • Preserve the MCL to avoid medial laxity

4

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
Pearls
  • 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
K

Trial Components and Confirm Balanced Knee

P

1

Place tibial base plate trial

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

2

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

3

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)

4

Confirm balanced flexion gap

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

5

Confirm AP stability

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

6

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)

7

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

8

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
Pearls
  • 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
L

Final Implant Placement

1

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

2

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

3

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

4

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

5

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
N

Wound Closure

1

Irrigate and obtain hemostasis once tourniquet is deflated

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

2

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

3

Perform superficial closure

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

4

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

O

Perioperative Inpatient Management

1

Write comprehensive admission orders

  • Advance diet as tolerated
  • Pain control
  • Wound management
  • Foley out when ambulating
  • Check appropriate labs
  • Antibiotics
  • Prescribe DVT Prophylaxis
  • Appropriately orders and interprets basic imaging studies
  • obtain post-op radiographs of the knee
  • Inpatient physical therapy
  • initiate physical therapy as soon as possible
  • weight bearing as tolerated
  • immediate range of motion exercises to knee

2

Appropriate medical management and medical consultation

3

Discharges patient appropriately

  • Pain meds
  • Wound care
  • Outpatient physical therapy/rehabilitation
  • Generally follow up in 2 weeks
R

Complex Patient Care

1

Develops unique, complex post-operative management plans

2

Diagnosis and management of complex complications

  • Infections
  • Thromboembolic events
  • Dislocations
  • Neurovascular compromise
 

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