Steps:

• Distal Femoral Resection
• It should be selected to be 2-5mm medial to the apex of the intercondylar notch and 7-10mm anterior to the origin of the Posterior Cruciate Ligament (PCL) , to make a 5-7cm depth of hole with 8mm Initiator Drill.
• Rotate the knob of Outrigger until the padlock symbol is aligned with arrow, then engage the Accurate Distal Femoral Cutting Block with the Distal femoral Jig and Cutting Block Clip.
• According to preoperative measuring, set the desired valgus angle ( 0°-9°) by pulling the handle of the Distal Femoral Jig , and each clip moves 1° .
• Insert Accurate Femoral IM Rod and attach Distal Femoral Jig to distal femoral tightly.
• Fix Distal Femoral Cutting Block with two Bone Pins.
• Press the button of Outrigger and remove Distal Femoral Jig.
• Use Accurate Reference Guide to make sure the resection thickness is whether appropriate or not.
• To achieve better stability, insert bone pin through one of oblique pin holes on Cynthia A/P Chamfer Block.
• To further adjust the distal resection depth, use the distal or proximal pin holes, that move the block 2 mm in either direction.
• Take distal femoral resection.
• Proximal Tibial Resection
• With the Height Adjustment Knob fully unscrewed on Accurate Extramedullary Tibial Proximal Uprod. Then attach Accurate Malleolar Clamp and Accurate Connecting Shaft for Malleolar Clamp to Accurate Extramedullary Tibial Proximal Uprod.
• For PS configuration, it is recommended to set the tibial posterior slope at 3 degrees. For CR configuration, a range of 5-7 degrees of tibial posterior slope is recommended.

• Three types of Tibial Cutting Block (left, symmetrical, right) can be provided.

• The resection level can be adjusted by using the proximal or distal pin holes, which move the block 2 mm in either direction.

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  Align the proximal central marking on the Accurate Tibial Cutting Block with the medial 1/3 of the tibial tubercle.

  
  

• Alignment can be checked by ensuring that Accurate Extramedullary Tibial Proximal Uprod remains parallel with the tibial axis.

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  Rotate any knobs of two sides on Accurate Malleolar Clamp, move Accurate Connecting Shaft for Malleolar Clamp to medial side of patient at 2-5mm.

  
  

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  Rest the pointer of Accurate Stylus on the lowest of tibial medial plateau. The resection level can be adjusted by using proximal and distal pin holes, and the 0 to 2mm thickness of resection is recommended.

  
  

• Or based on the lateral tibial plateau, rest the pointer of the Stylus on the highest point of the tibial plateau, the 8 to 10mm thickness of resection is recommended.

• After setting the height, insert Bone Pin into the standard holes of the Tibial Cutting Block.

• Press the button on the up side of the Accurate Extramedullary Tibial Proximal Uprod. Dissect the entire instrument from the Tibial Cutting Block.

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  Use Accurate Reference Guide to make sure the resection depth is whether appropriate or not.

  
  

• If not, the resection level can be adjusted by using the proximal or distal pin holes, which move the block 2 mm in either direction.

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  Perform a proximal tibial resection.

  
  

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  Extension Gap Assessment and Balancing

  
  

• To check the extension gap, fully extend the leg and place the appropriate end of the Spacer Block between two resected surfaces.

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  Block between two resected surfaces.

  
  

• The Block should fit snugly in the extension space

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  Further Resection of Distal Femur

  
  

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  Press and rotate the button of Cynthia Sizing Guider to verify appropriate position.

  
  

• The angles of 0°/3°/5°/7° are available. Left and right should be distinguished.

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  Place the Cynthia Sizing Guider against the resected surface of the distal femur with the posterior feet of the Guider contacting the posterior condyle.

  
  

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  When fixing the Pin, the Posterior Reference or Anterior Reference can be taken.

  
  

• Choosing the posterior up pin holes will provide a fixed posterior reference with a fixed posterior cut. All variability in bone cuts from size to size will occur on the anterior cut.

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  Adjust Accurate Stylus to the highest point of anterior femur to determine the size of Cynthia Femoral Cruciate Substituting Component.

  
  

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  Select appropriate Cynthia A/P Chamfer Block to matches the femur size and place the block over the bone pins through pin holes.

  
  

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  The resection level can be adjusted by using the upper or lower pin holes, which move the block 1mm in either direction.

  
  

• Before assembling the Modular Posterior Saw Capture, the flexion space can be checked at 90° of flexion by using Accurate Spacer Block which placed below the A/P Chamfer Block.

• Re-attach the appropriate size of Modular Posterior Saw Capture to the Cynthia A/P Chamfer Block to provide for capture guidance on all cuts.

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  Drives two Accurate Threaded Head Pins into the oblique holes on both sides of the Cynthia A/P Chamfer Block.

  
  

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  Remove the two Bone Pins from the center and perform the anterior/posterior bevel resection.

  
  

• The anterior groove is for anterior bevel resection, and the posterior groove is for posterior bevel resection.

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  Take out the Intercondylar Trial, and place the Cynthia PS Femoral Trial on the prepared femoral which locates at distal surface of the femur as far laterally as possible while assuring that the lateral border of implant does not overhang the lateral femoral cortex.

  
  

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  Impact the femoral condyle reversely to avoid it toward downside.

  
  

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  It is recommended to insert two Bone Pins in place to better fix the Cynthia Femoral PS Trial.

  
  

• Lock Cynthia Femoral Notch Guide with Chamfer Slots on the Cynthia Femoral Trial tightly.

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  Put the Accurate Fixation Sleeve (for cannulated Drill Bits) on the Accurate Drill Bit (cannulated), select the depth of the Accurate Fixation Sleeve (for cannulated Drill Bits) according to the specifications of the Cynthia PS Femoral Trial (show as the arrow).

  
  

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  Then use the corresponding Cynthia Osteotome for Intercondylar to remove excess intercondylar bone.

  
  

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  The Intercondylar Trial should slide smoothly into the Cynthia PS Femoral Trial.

  
  

• Use the Accurate Femoral Lug Drill to drill through the hole in the distal of the Cynthia PS Femoral Trial.

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  Select a Cynthia PS Tibial Insert Trial that matches the size and type of the femur, and place an appropriate thickness of Cynthia Spacer Shim.

  
  

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  When extending the knee, mark the position of Cynthia Tibial Tray Trial on the anterior tibial cortex.

  
  

• Remove the Cynthia Tibial Tray Trial, Cynthia PS Tibial Insert Trial and Cynthia PS Femoral Trial.

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  Place the Tibial Tray Trial on the marked line position, and use two Fixation Pins to fix the Tibial Tray Trial.

  
  

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  Assemble the Tibial Drill Tower on the Tibial Tray Trial. According to the specification of Tibial Tray Trial, adjust the Accurate Drill Sleeve to the appropriate depth, and drive the Accurate Tibial Drill to the stop.

  
  

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  Attach the correct size of Cynthia Keel Punch to the Accurate Impaction Handle, and insert it to the limit depth via Cynthia Tibial Drill Tower Guide. Remove the Cynthia Tibial Drill and Cynthia Keel Punch and pay attention to keep the keel shape.

  
  

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  Component Implantation

  
  

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  Cleansing the bone with pulsatile lavage, taking care to dry the bone afterwards.

  
  

• Apply a thick layer of bone cement to the tibia and / or the implant surface.

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  Assemble the femoral component, the tibial insert and the tibial tray fixed bearing.

  
  

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  Select appropriate thickness of Cynthia PS Tibial Insert Trial and Cynthia Spacer Shim.

  
  

• Insert the Tibial Insert Trial into the joint during knee flexion and make reduction for joint.

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  At extending status, make slight axis pressure, then wait cement cured.

  
  

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  Position Tibial Insert Impactor at approximately 60 degrees on Tibial Insert, so that the impactor notch rests on the central anterior edge of the Tibial Insert.

  
  

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  Check range of knee joint motion, clean joint cavity and suture the knee joint layer by layer.