DISCLAIMER: The following steps are summarized and do not constitute full operative instruction. Please refer to the package insert(s) or other labeling associated with the devices identified in the full surgical technique for additional information.

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SUMMARY: Determine the skin incision location. 

  • Place a guidewire on the patient perpendicular to the axis of the spine at the targeted level. 

  • Using A-P fluoroscopy, position the guidewire such that its projection transects the center of both pedicles in the cephalad-caudal direction. 

  • Use a surgical marker to transfer that plane to the patient. (Fig 3)

OR Setup Fig 3
  • Place guidewires on the patient parallel to the axis of the spine. 

  • Using A-P fluoroscopy, position the guidewire such that its projection aligns to the lateral pedicle wall of the targeted level and the adjacent levels. 

  • The lateral pedicle wall of adjacent levels may also be estimated at this time. 

  • Use a surgical marker to transfer this plane onto the patient. 

  • The longitudinal skin incision for each level should be at least 1 cm lateral to the intersection of the two lines. 

Note: This distance may vary depending on size of the patient.

SUMMARY: Assemble the VIPER PRIME Inserter components. 

  • The Inserter is made up of 4 components:

carrier for percutaneous pedicle screw placement

1. Carrier (Fig 4)

drive tube for percutaneous pedicle screw placement

2. Drive Tube (Fig 5)

red stylet control handle for percutaneous pedicle screw placement

3. Red Stylet Control Handle (Fig 6)

shaft for percutaneous pedicle screw placement

4. Shaft (Fig 7)

carrier drive inserted into drive tube for VIPER PRIME inserter
  • Insert the Carrier into the Drive Tube with the red line indicator facing into the tube. (Fig 8)
 red stylet control handle inserted onto drive tube for VIPER PRIME inserter
  • Thread the Red Stylet Control Handle over the Carrier until it is seated on the Drive Tube. This is a reverse thread and should be rotated counterclockwise to assemble. (Fig 9)
drive tube attachment for VIPER PRIME inserter
  • Insert the tabs of the Drive Tube into the Shaft. (Fig 10) Ensure that the two set screws on the sides of the Shaft are fully backed out before trying to attach the Drive Tube. You will hear an audible click when the Drive Tube properly snaps into place.
 set screw adjustment on VIPER PRIME inserter
  • Using the Set Screw Driver, hand-tighten both set screws on the Inserter Shaft. (Fig 11)
modular handle attachment to VIPER PRIME inserter
  • Select a VIPER PRIME Modular Handle (T-handle or Palm) and attach to the proximal end of the Inserter. These will snap into place over the spring tabs of the Drive Tube. (Fig 12)
  • The Modular Handle may be removed at any time for visualization.

SUMMARY: Determine the screw length and load onto inserter

Inserter tip attachment for VIPER PRIME inserter
  • Select the screw size (length and diameter) based on pre-operative imaging and planning and load onto the VIPER PRIME Inserter. 
  • Ensure that the Inserter is fully seated in the screw drive feature, and then tighten the green knob to the proximal threads on the screw tabs to secure the implant. (Fig 13

Caution: The Inserter tip can strip if the Inserter is not fully seated during screw insertion.  

  • The dark etch line on the Inserter Shaft should line up with the most proximal etch line on the X-Tab. This ensures that the shaft drive feature is fully engaged with the implant screw shank.

SUMMARY: Loading stylet onto VIPER PRIME Inserter. Optional dilator insertion.

  • On the Stylet Depth Adjustor, identify the slot that corresponds to the chosen screw length. (Fig 14)
stylet depth adjustor rotation
  • Remove the Stylet from sterile packaging. 
  • Ensure that the slot on the retaining sleeve is rotated into the “Open” position so that the slots are aligned. (Fig 15)
stylet inserted into depth adjustor
  • Insert the distal tip of the Stylet through the distal ring on the Depth Adjustor and place the proximal flange of the Stylet in the slot for the identified screw length. (Fig 16)
depth adjustor with stylet retained
  • Rotate the retaining sleeve on the Depth Adjustor 180 degrees to capture the stylet and make sure it is properly retained. (Fig 17)
stylet and depth adjustor inserted into viper prime inserter
  • Insert the Stylet and the Depth Adjustor into the top of the VIPER PRIME Inserter. (Fig 18)
     
stylet and depth adjustor inserted into viper prime inserter
  • Use the X25 Set Screw Driver to thread the Depth Adjustor into the assembled Inserter until it is fully seated. (Fig 19)
stylet depth gauge indicator on viper prime inserter
  • It is recommended to use a Modular Handle at this point to provide countertorque during Depth Adjustor insertion. 

  • Turn the Red Stylet Control Handle counterclockwise until it stops to fully retract the Stylet. 

  • Confirm that the Stylet tip extends approximately 3 mm beyond the distal tip of the screw in this position as indicated by the red line visible through the drive tube window on the Stylet Depth Gauge. (Fig 20)

dilator inserted into dilator sleeve

Precaution: If the Stylet is not visible beyond the screw tip or you cannot retract it to 3 mm, disassemble the Depth Adjustor and confirm that the stylet flange is seated in the appropriate screw length slot. 

  • The Stylet can be extended to a maximum of 25 mm beyond the tip of the screw. 

  • Consider a traditional Jamshidi and guidewire technique if the Stylet cannot be advanced or retracted using the Red Stylet Control Handle at any point in the procedure. 

  • OPTIONAL: Dilator Insertion 

  • Assemble the Dilator to the Dilator Sleeve. The instruments will snap together. (Fig 21

dilator insertion during percutaneous pedicle screw placement
  • Advance the assembled instrument until the distal tip contacts the pedicle. Confirm placement with fluoroscopy. (Fig 22)
dilator removal during percutaneous pedicle screw placement

Note: The metal tip will be visible under fluoroscopy. 

  • Push down on the Dilator Sleeve while pulling back on the Dilator until it separates from the Dilator and contacts the bone. 

  • Remove the Dilator while holding the Dilator Sleeve in place. (Fig 23)

SUMMARY: Advancing the stylet and confirm the final position of the Stylet using A/P and lateral fluoroscopy.

viper prime inserter advancing stylet during percutaneous pedicle screw placement
  • Insert the VIPER PRIME Inserter assembly through the incision and dock the stylet tip on the bony anatomy of the desired level. 

Note: At initial insertion, the Stylet should extend past the tip of the screw to dock onto the pedicle. The Stylet can be extended further if needed to adequately dock to the posterior anatomy. 

  • Confirm the position using fluoroscopy. (Fig 24)

viper prime inserter extending stylet for percutaneous pedicle screw placement
  • Targeting forceps can be used to keep the surgeon’s hand out of the fluoroscopy field. 

  • Attach the forceps just above the green knob on the Inserter

viper prime inserter extending stylet for percutaneous pedicle screw placement
  • To extend the Stylet relative to the screw tip, turn the Red Stylet Control Handle clockwise. As the handle is turned, each “click” represents approximately 1 mm of stylet extension. 

  • Extend the Stylet no more than an additional 5 mm while applying gentle downward pressure to ensure the Stylet remains docked. (Fig 25 & 26)

viper prime inserter extending stylet for percutaneous pedicle screw placement
  • The screw will rise as you extend the Stylet. 

  • Using a mallet, gently tap the Modular Handle to advance the Stylet into the pedicle. 

Precaution: It is not recommended to mallet on the Stylet when it is extended more than 5 mm beyond the tip of the screw outside of the bone. 

  • Use the etched markings on the X-Tabs to ensure that you do not mallet the screw tip into the pedicle. 

Note: Observe where the etched lines are relative to the skin prior to extending the Stylet once it is docked. This is your reference for when the screw tip is docked on the bone. 

  • Confirm the Stylet trajectory and position using A/P fluoroscopy. 

Warning: If the Stylet trajectory is not monitored by fluoroscopy, there is a potential for pedicle or anterior wall breach, potentially resulting in neurological damage or damage to the great vessels. 

  • Observe screw position relative to the skin level using the markings on the X-Tabs as you extend the Stylet. 

  • Continue to advance the Stylet up to 5 mm at a time until it is fully advanced through the pedicle, up to a distance of 25 mm. 

  • Confirm the final position of the Stylet using A/P and lateral fluoroscopy. (Fig 27 & 28)

viper prime inserter extending stylet for percutaneous pedicle screw placement

Note: The distance between the tip of the Stylet and the tip of the screw is represented by the red line on the Stylet Depth Gauge which has 5 mm increments at the proximal end of the VIPER PRIME Inserter to help estimate the depth of the Stylet. This can be used to track the position of the Stylet while it is being advanced into the pedicle. 

  • The 3 mm starting protrusion of the Stylet can vary ±1.4 mm due to allowable manufacturing tolerances.

SUMMARY: Advancing the screw into the pedicle and inserter removal.

viper prime inserter advancing screw into pedicle for percutaneous pedicle screw placement

132095-210819_ATP_Screw_Placement.mp4 (Timecode 1:17-1:40 ATP_Screw_Placement_Clip3)

  • Once the Stylet has been extended, HOLD THE RED STYLET CONTROL HANDLE while rotating the proximal handle of the Inserter clockwise to advance the screw into the pedicle over the extended Stylet. 
  • Use the depth markings on the X-Tab to monitor the travel of the implant relative to the skin. (Fig 29)

viper prime inserter advancing screw into pedicle for percutaneous pedicle screw placement

Warning: It is critical to hold the Red Stylet Control Handle at all times while advancing the screw. Holding the Red Stylet Control Handle will retract the Stylet as the screw is advancing into the pedicle. As a result, the tip of the Stylet will not advance further into vertebral body as the screw is inserted. If the Red Stylet Control Handle is not held, the Stylet will remain extended and advance in front of the screw, potentially leading to an anterior wall breach, neurological damage or damage to the great vessels. 

  • Reference the etched lines on the X-Tab to check that they move relative to the skin to ensure the screw is advancing. 

Note: Once the Stylet is fully retracted, the Red Stylet Control Handle will no longer rotate independent of the Inserter assembly. 

  • The tip of the Stylet is now approximately 3 mm beyond the tip of the screw and can be confirmed by the red line position on the Stylet Depth Gauge at the proximal end of the Inserter. 

  • At this point, release the Red Stylet Control Handle and insert the screw the remaining distance using the proximal handle until the screw is fully seated. 

Tip: Be sure that the polyaxial head is still mobile when the screw is seated. (Fig 30

removing viper prime inserter after advancing screw during pedicle screw placement

Warning: It is recommended that fluoroscopy be used while inserting the screw to monitor the depth of the screw and ensure that the Stylet is not unintentionally advanced, which might lead to a breach of the anterior wall of the vertebral body, neurological damage or damage to the great vessels. 

  • Disengage the screw from the Inserter by fully unthreading the green knob from the proximal threads of the implant and remove the Inserter and Stylet using the Red Stylet Control Handle.  

  • Use caution when removing the Stylet from the screw. (Fig 31)

viper prime inserter stylet adjustment for percutaneous pedicle screw placement

Insertion of Additional Screws

Follow the previous steps for the remaining screws. 

Note: If the length of the subsequent screw is the same, the Stylet and Depth Adjustor do not need to be changed. 

Note: If the length of the subsequent screw is different, remove the Depth Adjustor using the Set Screw Driver. 

  • Open the retaining sleeve and move the Stylet flange to the appropriate slot for the new screw length. (Fig 32

Tip: After each screw, visually check the Stylet to ensure that it has not been damaged or bent during screw insertion. If it has, replace the Stylet with a new one before proceeding to the next screw.

viper prime fenestrated alignment device aligning screw during percutaneous pedicle screw placement

Information

  • When used in conjunction with CONFIDENCE SPINAL CEMENT SYSTEM™, the VIPER PRIME Fenestrated Screws are intended to restore the integrity of the spinal column even in the absence of fusion for a limited time period in patients with advanced stage tumors involving the thoracic and lumbar spine in whom life expectancy is of insufficient duration to permit achievement of fusion. 
  • The VIPER PRIME Fenestrated Screws augmented with CONFIDENCE SPINAL CEMENT SYSTEM are for use at spinal levels where the structural integrity of the spine is not compromised. 

Alignment of the Screw 

  • The patient should be positioned prone lying face down in procedures where  
    VIPER PRIME Fenestrated Screws are augmented with cement. 

  • Insert the VIPER PRIME Fenestrated Alignment Device into the VIPER PRIME X-Tab and thread it into the screw head while holding the X-Tabs to provide counter torque. This will align the screw shank to the screw head. (Fig 33 & 34)

viper prime fenestrated alignment device aligning screw during percutaneous pedicle screw placement
  • Confirm that the alignment device is fully seated by checking that the alignment device handle and top of the X-Tab are in close proximity. The head will be locked to the shank when it is properly aligned. 

Attachment of Additional Alignment Devices 

  • Repeat until Alignment Devices are attached to all levels intended for cement augmentation. 

Tip: Do not mix the CONFIDENCE System cement until all alignment devices are attached at each level intended for augmentation. 

Warning: The lateral decubitus position is not intended for cement augmented procedures with fenestrated screws. 

Precaution: The alignment guide MUST be used for each screw intended for cement augmentation. Without the alignment guide, there is a potential risk of cannula breakage. Use of the alignment guide will prevent undue stress from being applied to the cannula. 

Cement Preparation and Delivery 

  • Once the screws are in place and the Alignment Devices are attached to the levels selected to be augmented, please refer to the VIPER™ Cortical Fix Fenestrated Screw System Guide for instructions on Cement Preparation and Delivery. 

Precaution: Only the open cannulas are compatible with the VIPER PRIME X-Tabs. 

  • Remove the alignment devices after cement has been delivered by holding the X-Tab and unthreading the device. 
     

SUMMARY: Determining the rod length and rod holder insertion.

rod gauge use during percutaneous pedicle screw placement
  • Insert one arm of the Rod Gauge into each of the outermost X-Tabs until each leg is fully seated in the screw heads. 

Tip: Placement can be verified by ensuring that the circumferential lines on the shafts of the Rod Gauge align with the top of each X-Tab. (Fig 35)

rod holder push rod for percutaneous pedicle screw placement
  • Straight rods can be measured using the markings on the Rod Gauge leg. 

  • The X-Tabs must be parallel to each other and the Rod Gauge should be laid on the body so that the legs are perpendicular to the tabs to ensure accurate measurement. 

  • Etch lines should be aligned with the outside edge of the X-Tabs for straight rod measurements. 

  • Length markings indicate rod length including rod overhang. 

  • No additional rod length allowance is required. 

  • Select the rod that corresponds with the indicated rod length.  

  • If the measurement is between two lengths, it is recommended to select the longer rod. 

  • The measurement accuracy of the Rod Gauge can vary ±1.2 mm due to allowable manufacturing tolerances. 

Assemble the Rod Holder

  • The Rod Holder is made up of three components:

    1. Push Rod (Fig 36)

rod holder stem for percutaneous pedicle screw placement

2. Rod Holder Stem (Fig 37)

rod holder threaded shaft for percutaneous pedicle screw placement

3. Threaded Shaft (Fig 38)

rod holder assembly for percutaneous pedicle screw placement   Attach Rod to the Rod Holder
  • Insert the Push Rod into the Rod Holder Stem. Ensure that the Push Rod is fully seated before inserting the Threaded Shaft. 

  • Thread the shaft into the top of the Rod Holder Stem. (Fig 39)

 rod attached to rod holder for percutaneous pedicle screw placement

Attach Rod to the Rod Holder 

  • Insert the connection end of the rod into the pocket of the Rod Holder ensuring that the V-notch on the connection end of the rod is facing up towards the handle of the Rod Holder. (Fig 40)

knob adjustment on rod holder for percutaneous pedicle screw placement
  • Tighten the knob on the proximal end of the Rod Holder to capture and lock the rod. Verify that the rod is securely attached to the Rod Holder. (Fig 41)

Rod Insertion

rod insertion for percutaneous pedicle screw placement
  • Align the slots of the X-Tabs so that they are in line with each other to allow for passage of the rod. Position the VIPER PRIME Rod Holder parallel to the skin’s surface with the tip of the rod facing downward. (Fig 42)
rod insertion for percutaneous pedicle screw placement
  • Insert the Rod Holder Assembly through the cranial screw extension tab, and advance the Rod Holder into the slot of the caudal Screw X-Tab(s). The entire rod should be contained within the X-Tabs. 

  • Use the Rod Holder to align the Screw X-Tabs until they are parallel with one another. 

  • Advance the distal end of the rod towards the screw, down the caudal X-Tab until it touches the top of the screw head or it is as deep as the tissue will allow. It is necessary for the distal end of the rod to be below the fascia before proceeding. 

  • The rod is fully seated when the laser-etch line on the stem of the Rod Holder is aligned with the top of the X-Tabs. (Fig 43)

  • To verify the rod has passed through the screw, twist the X-Tabs.  

Note: If the tab is able to rotate, the rod is not contained within the tab and rod placement should be re-attempted. 

Tip: Fluoroscopy should be used to verify adequate rod overhang at each end of the construct.

 

SUMMARY: Placing set screws and rod holder removal.

set screw driver in set screw caddy
  • Ensure that the Set Screw Driver Handle is in the unlocked position. 

  • Slide the Inserter lid on the Set Screw Caddy to uncover a single set screw. This will prevent other set screws from inadvertently becoming dislodged during set screw loading. (Fig 44)

set screw driver in set screw caddy
  • With the set screw in the caddy, fully seat the Set Screw Driver into the set screw. 

  • Raise and drop the slap handle to secure the set screw to the Set Screw Driver. 

  • Return the handle to the proximal end of the Set Screw Driver and lock in place. (Fig 45)

set screw driver advancing set screw for percutaneous pedicle screw placement
  • Use the Set Screw Driver to advance the set screw through the extension tabs and into the screw head. 

Tip: It is recommended to begin with the set screw closest to the Rod Holder. (Fig 46)

set screw driver advancing set screw for percutaneous pedicle screw placement

Precaution: If substantial reduction forces are expected during set screw insertion, the VIPER PRIME Counter-Torque should be used. This will allow the Set Screw Driver to fully reduce the rod into the head of the polyaxial screw and reduce the chance of tab splay and subsequent set screw cross threading. 

  • Once the proximal laser etch band on the shaft of the Set Screw Driver is in line with the top of the screw X-Tabs, then the set screw and rod are fully seated within the screw head. (Fig 47)

  • Repeat for all screws 

  • Slap handle can be used to remove the Set Screw Driver from the set screw 

  • After all set screws are placed, remove the Rod Holder. 

  • If further correction is needed, remove the set screw Driver and proceed to next step. If no further correction is needed, proceed to final tightening

viper prime compressor driver leg for percutaneous pedicle screw placement

The Compressor consists of three components: 

1. Driver Leg (Fig 48)

viper prime solid compressor for percutaneous pedicle screw placement

2. Solid Compressor Leg (Fig 49)

viper prime x25 compressor driver for percutaneous pedicle screw placement

3. X25 Compressor Driver (Fig 50)

viper prime driver leg attaching to implant for percutaneous pedicle screw tightening
  • Final tighten one set screw and provisionally tighten the remaining set screws.

  • Please refer to Step 9 for final tightening instructions. 

  • Place the Driver Leg (1) through the X-Tab at the provisionally tightened set screw. (Fig 51)

viper prime driver leg securing for percutaneous pedicle screw tightening
  • Secure the Driver Leg to the implant by threading the green knob onto the external threads at the proximal end of the X-Tab. (Fig 52)
viper prime solid compressor leg attaching to x-tab for percutaneous pedicle screw tightening
  • Place the Solid Compressor Leg (2) through the X-Tab with the final tightened set screw. (Fig 53)
viper prime solid compressor leg seated on set screw for percutaneous pedicle screw tightening
  • Orient the foot of the Solid Compressor Leg so that it seats on the edge of the set screw and faces towards the disc space intended for compression. (Fig 54)
compressor leg connection for percutaneous pedicle screw tightening
  • Connect the compressor legs by sliding them together axially or by depressing the spring tab and sliding them together laterally. (Fig 55 & 56)
compressor leg connection for percutaneous pedicle screw tightening
viper prime x25 compressor driver inserted through the driver leg for percutaneous pedicle screw tightening
  • Insert the X25 Compressor Driver (3) through the Driver Leg. (Fig 57)
tightening of percutaneous pedicle screws using compressor
  • Slightly loosen the provisionally tightened set screw until the rod is free to slide in the screw head.

tightening of percutaneous pedicle screws using compressor
  • Squeeze the two handles together to compress while provisionally tightening the set screw. (Fig 58 & 59).
compressor release after percutaneous pedicle screw tightening

Precaution: The X25 Compressor Driver is only designed to be a provisional set screw tightener and not a final tightener. The Set Screw Driver and Final Tightening Torque Handle provided in the VIPER PRIME Instrument Set should be used for final tightening. 

  • Release the Compressor by unthreading the knob on the Driver Leg and remove both legs from the implants. (Fig 60 & 61)

compressor release after percutaneous pedicle screw tightening
  • For multi-level constructs, it is recommended to perform segmental compression.

SUMMARY: Final tightening and tab removal.

counter-torque positioned over x-tabs for percutaneous pedicle screw tightening
  • Using fluoroscopy, verify that the rod connection feature and bullet nose are both fully outside the screw heads.

counter-torque positioned over x-tabs for percutaneous pedicle screw tightening
  • To perform final tightening, place the Counter-Torque over one of the X-Tabs. Ensure that the notches of the counter-torque straddle the rod. (Fig 62 & 63)
viper prime set screw driver attached to final tightening torque handle   Laser markings on the proximal end of the Counter-Torque Tube indicate the orientation of the rod slots.
  • Attach the Set Screw Driver to the Final Tightening Torque Handle with the handle in the lower locked position, pass through the X-Tab, and engage the set screw. (Fig 64)

final tightening of set screws after percutaneous pedicle screw placement
  • Laser markings on the proximal end of the Counter-Torque Tube indicate the orientation of the rod slots. 

  • Rotate the Torque Wrench Handle clockwise, while applying counter-torque, until the torque handle clicks. The final torque applied will be 80 in-lbs. Repeat for all additional set screws. (Fig 65)

  • It is recommended to revisit all set screws to ensure a rigidly locked construct post operatively.

Tip: Set screws should be flush with the top of the screw heads indicating they are fully seated. This can be confirmed using fluoroscopy. 

X-Tab Removal

  • Place the Tab Breaker over one tab ensuring the nose is in the rod slot. 

  • Advance the Tab Breaker until it reaches the set screw and can no longer be advanced.

viper prime tab breaker alignment

Tip: The laser marked line on the body of the Tab Breaker will line up with the top of the tab when fully seated. (Fig 66)

viper prime tab breaker breakaway action
  • Rock the Tab Breaker outward (away from the center of the screw) until the tab breaks away from the Screw Head. (Fig 67)

  • If a decision is made to remove the implants after solid fusion occurs, the following steps should be taken after the implant is exposed.  

  • For set screw, rod and screw removal:  

    • Clean debris/tissue from set screws. 

    • Connect the Torque Handle to the X25 Set Screw Inserter 

    • Insert Counter Torque over targeted screw and engage Inserter with set screw 

    • Turn the handle counter-clockwise to loosen set screw while applying counter torque 

    • Once the set screws are removed, the rods can be removed 

    • Engage Set Screw Inserter with screw shank and turn handle counter-clockwise to remove screw.