- General
- Very strong screw because
- It is long
- Anterior to the McCord pivot point
- Tricortical purchase
- Includes all 3 O’Brien zones
- Ref:
- Advantages:
- Merge the benefits of iliac and sacral fixation
- Less soft tissue dissection
- Lower implant prominence → less wound complication rate
- Better in-line connection with cephalad instrumentation;
- Less soft tissue dissection.
- Indication
- Trauma: Spinopelvic dissociation
- Tumor resections
- Nonunions
- Osteomyelitis with bone loss
- Pathologic fractures
- High-grade spondylolisthesis
- Spinal deformity surgeries
Positioning
- Iliac Crests:
- Should be symmetrically positioned
- Must be horizontal to the floor
- Draping:
- Ensure lateral & distal access to PSIS (Posterior Superior Iliac Spine)
- Inappropriate Positioning
- Can cause changes in pelvic obliquity
- Can lead to sacral tilt
- Nothing should block imaging of the pelvic area
Guidance
- Fluoroscopic:
- two 30, 30 deg views
- Tear drop view
- To check that direction is going towards the tear drop (ASIS)
- To check that the bone pin is within the bone
- Sciatic notch view
- to check that the needle is going into the direction
- Navigated
- Navigation frame is mounted on the spinous process of the lumbar vertebrae.
- The entry point has to be determined on a CT scan preoperatively or intraoperatively and is same as that with free hand technique.
- Errors are minimized using the metallic frame attached to the spinous process.
- It is of paramount importance that the screw size and trajectory is determined on the CT scan.
- Ganga technique
- Use navigation probe to identify entry point and trajectory
- Drill with a 2mm cutting burr the starting hole
- Use navigation prove to make sure the trajectory is correct and drill some more unti breeched the SI joint.
- Use a pedicle probe to push through the Ilium
- Screw sized around 110mm x 8-9mm screw
- Screw inserted
- Phan 2017 technique
- used K wire and Jamshidi needle to create the trajectory that was determined on the CT scan.
- Once the track is created, screw is inserted.
- Entry point
- Between S1 and S2 foramina
- Medial to the lateral sacral creast
- Trajectory
- Aim towards the greater trochanter
B- Once no breach is confirmed, k wire is inserted.
C- Tapping and size of screw is determined.
D- Finally, the screw is inserted.
- Pass Jamshidi first then after sciatic notch view pass wire down as far as possible
- Final screw position
Complications
- Screw malposition and neurovascular injuries:
- Medial to ilium – Internal iliac vessels
- Below the sciatic notch – Sciatic nerve and superior gluteal artery
- Windshield wiper effect
- Implant prominence and wound healing problems
- Iatrogenic fractures
- Sacroiliitis
- Gait disturbance:
- Mobility between spine and pelvis needed for normal gait
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