[Pedicle closing-wedge osteotomy for the treatment of fixed sagittal imbalance]

The aim of this study was to analyze x-ray results in patients who underwent pedicle subtraction osteotomy for complex deformations (flat back, kyphosis) leading to fixed sagittal imbalance.

Thirty-four patients underwent surgery between 1996 and March 2003 in two centers, the orthopedic surgery unit devoted to spinal surgery and sports traumatology at the Strasbourg University Hospitals and the spinal surgery unit at the Chenove Clinic (Dijon). The series included 20 women and 14 men, mean age 46.5 years (range 14-74 years) treated for: postoperative flat back (n = 19), kyphoscoliosis (n = 6), ankylosing spondylarthritis (n = 5), and malunion (n = 4). After careful planning to achieve the necessary degree of correction, the patient was installed on a Cotrel table with a stable support enabling limited blood loss and facilitated reduction maneuvers via elevation of the lower limbs. The technique started by resection of the posterior arch, the transverse processes, and the pedicles, followed by partial resection of the body with a chisel under fluoroscopic control. The closure was achieved by in situ reduction with compressive rotation. Adjacent discs were then evaluated to search for any opening which could be filled by an anterior graft to complete the stabilization. The osteosynthesis used 2-, 4-, and 6-rod assemblies. The 6-rod assemblies enabled anchoring the fixation above and below before the osteotomy. Two prebent rods completed the assembly at reduction after osteotomy. Weight-bearing started on day 4. A protective corset was worn for three months by 19 patients. The patients resumed their occupational activities on average 6.73 months postoperatively without change in activity for 63%. Overall satisfaction was close to 90% excellent outcome.

All clinical results were analyzed with the Profil software of Surgiview. X-ray data were analyzed with Spineview. A self-administered clinical questionnaire was used to evaluate pain, result of the operation, and the impact on the patient's body image. On average, the wedge osteotomy measured 28.9 degrees for correction of lumbar lordosis by 31.5 degrees with a maximum of 65 degrees. The misalignment at C7 was reduced from 51 mm to 2 mm. At the pelvic level, version improved 16 degrees, sacral slope 8 degrees. There were four dura mater breaches which had to be sutured, but with no clinical consequence (one progression to meningocele). Mean intraoperative blood loss was 1400 cc (300-4500cc) for a mean operative time of 260 minutes (165-450 min). There were two early infections at day 15 postop which resolved with antibiotics. Four patients developed resolutive sciatica (n = 2) or cruralgia (n = 2) during the following months. The short-term follow-up revealed eight non-unions (25%) with rupture of osteosynthesis material and loss of correction. The opening in the adjacent discs and the insufficient posterior closure explained this mechanical complication.

Pedicle subtraction osteotomy is an original operative technique reserved for specialized centers. A well-experienced team is needed to control the risks involved. Sagittal balance should be one of the important goals for modern spinal surgery.