M. Timothy Hresko

Pars Repair

Operative Indications

  • Failed nonoperative treatment of documented pars intra-articularis defect

  • MRI—absence of intervertebral disk degeneration

  • Less than 5 mm of translation of superior vertebral body

  • Pain relief on pars injection


  • Prone on radiolucent table (Figure 7.1A)

  • Flex hips to reduce anterior pelvis tilt and lumbar lordosis (Figure 7.1B)

Procedure-Specific Checklist

  • Implant for your specific procedure

  • Intraoperative fluoroscopy to confirm surgical site at correct location

  • Compare to preop imaging—be cognizant of transitional LS vertebrae

Surgical Approach

  • Surface landmark of dimple of Venus (posterior iliac spine) at level of S1 spinous process

  • Midline approach 8 cm cephalad from S1

  • Raise skin flap to iliac crest

  • Elevate muscle from L5 lamina to L4-L5 facet, lateral to base of transverse process (if using Scott wire technique elevate to tip of TP and ventral on the specific vertebrae)

  • Maintain ligament of posterior process to L4, L5, S1

Techniques in Steps

Common to All Technique

  • Obtain bone graft from iliac crest—cancellous

  • Use Rongeur, curette, or burrs to clean out pars defect

  • Buck screw technique (Figure 7.2A-C)

    • Preoperative CT to confirm lamina intact—absence of bifid lamina

    • Use fluoroscopy and K-wire to plan path for cannulated drill AP and lateral fluoroscopy

    • Burr starting point at inferior aspect of ipsilateral lamina

    • Percutaneous insertion of threaded guide pin for cannulated drill inserted midline and distal to incision, angled lateral and ventral under fluoroscopy

    • Advance guide pin to pars defect

    • Place bone graft

    • Advance guide pin to anterior superior cortex

    • Drill over wire and far cortex

    • Remove wire and place solid 4.5 mm screw—bicortical

    • Repeat on contralateral side

    • Decorticate base of TP and lamina

    • Place additional bone graft on lamina

    • Close wound

  • Scott wire technique (Figures 7.3 and 7.4)

    • Pass loop wire over lateral aspect of TP to base of TP

      • Alternative is place pedicle screw or bone screw and washer in pedicle and loop wire under the washer

    • Decorticate base of TP and lamina

    • Pass free end of wire through posterior ligament in “figure of 8” fashion and secure on contralateral side of spinous process

    • Insert bone graft in pars defect and lamina ventral to wire

    • Place contralateral wire in a similar fashion

    • Tighten both wires

    • Close wound

  • Pedicle screw

    • Place bilateral polyaxial pedicle screws avoiding facet joint

    • Decorticate base of TP and lamina

    • Insert bone graft into pars defect, base of TP, and lamina

    • Implant secured to posterior process. Implant options:

      • Contour 4.5 mm rod in “U” shape passed rod inferior to L5 spinous process

      • Polyethylene cord instead of rod (physician directed use, not FDA approved)

      • Wire

    • Insert rod into pedicle screw head and compress

Postoperative Care

  • Optional use of lumbosacral orthosis

  • Out of bed to chair and ambulate as tolerated

  • Short course of oral opioid; avoid nonsteroid anti-inflammatory drugs

  • Restricted lumbar hyperextension/flexion activity 4 to 6 weeks

  • CT scan at 3 months to assess healing and return to conditioning for sport

Jun 9, 2022 | Posted by in Reconstructive surgery | Comments Off on Spondylolysis/Spondylolistheses
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