Minimally invasive technique for direct repair of pars interarticularis defects in adults using a percutaneous pedicle screw and hook-rod system.

In this report, the authors described a new minimally invasive technique to repair pars interarticularis defects in adults. The well-established technique using the pedicle screw (PS) and hook-rod system was modified. First, bilateral PSs were inserted percutaneuosly using the Sextant system. Then, through a small skin incision (3-4 cm), an illuminated tubular retractor (Quadrant system; Medtronic Sofamore Danek) was inserted into the pars defect. When this system is used, it is not necessary to detach all the back muscles to access the lytic part. The bursa and fibrocartilaginous mass near the defects were removed. After decortication of the pseudarthrosis at the spondylolytic level, bone grafts were implanted. Finally, the hook part of a hook-rod system was attached to the lamina and the rod was secured at the tulip head of the PSs. The authors performed this procedure in 2 adult patients, 32 and 24 years of age. Immediately after surgery both patients' low-back pain disappeared, and by 3 months postoperatively both had returned to their original work or sports activities.