Posterior correction using pedicle screw fixation combined with bone grafting and fusion for treatment of severe and rigid adolescent idiopathic scoliosis in 20 cases

Weiping ZANG; Zude LIU; Zhanchun LI; Yu FENG; Lei ZHANG

ABSTRACT

BACKGROUND:

Traditional anterior release followed by posterior correction and fusion is frequently used to treat severe and rigid adolescent idiopathic scoliosis, which is considered as Cobb angle of the major curve > 65° and flexibility < 34.5%; however, there are a great majority of complications. Whether isolated posterior correction using pedicle screw fixation combining with bone grafting and fusion may provide better effects on severe and rigid adolescent idiopathic scoliosis needs to be further studied.

OBJECTIVE:

To evaluate isolated posterior correction using pedicle screw fixation combining with bone grafting and fusion for the treatment of severe and rigid adolescent idiopathic scoliosis.

DESIGN:

Case analysis.

SETTING:

Department of Orthopaedics, Renji Hospital, Medical College of Shanghai Jiao Tong University.

PARTICIPANTS:

Twenty patients with severe and rigid adolescent idiopathic scoliosis, including 8 males and 12 females, were selected from Department of Orthopaedics, Renji Hospital, Medical College of Shanghai Jiaotong University from June 1999 to August 2005. They were 12-18 years old, and the mean age was 14.6 years. All patients were finally diagnosed as X-ray of whole spine. According to King-Moe criteria, patients were classified into type Ⅰ(n =4), type Ⅱ(n =6), type Ⅲ (n =5), type Ⅳ(n =3) and type Ⅴ(n =2). Before surgery, mean Cobb angle of the major curve was 82° (75°-92°), mean flexibility was 30% (20%-40%), and mean shoulder height difference was 15 mm (5-35 mm). Moreover, according to Risser syndrome, patients were classified into degree 1 (n =3), degree 2 (n =5), degree 3 (n =6), degree 4 (n =5) and degree 5 (n =1). All patients and their relatives provided the informed consents, and the experiment was approved by the local ethical committee. Artificial bone was Osteoset provided by Wright Company, USA.

METHODS:

Patients underwent isolated posterior correction using pedicle screw fixation combining with bone grafting and fusion, and spinous process, lamina of vertebra, zygapophysial joints and transverse process were exposed in a preconcerted fusion area. Pedicle screw was inserted into strategy vertebra using free hand technique according to the anatomic landmark of entry point. Six patients underwent fixation with TSRH system, and the other patients with CDH M8 system. Operative time and blood loss were evaluated after surgery. At 7 days after operation, Cobb angle was measured with X-ray, and correction rate of major curve was calculated. While shoulder height difference and admission duration were evaluated simultaneously. Complications and recovery states were followed up in the next 4 years.MAIN OUTCOME

MEASURES:

① Operative time and blood loss; ② Cobb angle and correction rate of major curve; ③ shoulder height difference and admission duration; ④ follow-up results.

RESULTS:

All 20 patients were included in the final analysis. ① Operative time and blood loss Operative time lasted from 3.2 to 4.3 hours, and the mean time was 3.5 hours. Blood loss ranged from 660 to 1 070 mL, and the mean loss was 865 mL. ② Cobb angle and correction rate of major curve Cobb angle of the major curve ranged from 82° (75°-92°) before surgery to 31° (22°-37°) after surgery, and the mean correction rate was 62%. ③ Shoulder height difference and admission duration Mean should height difference before surgery was 15 mm (5-35 mm). Postoperative lateral film of spine indicated that thoracic and lumbar vertebra generally suffered from normal posterior and anterior convexity, and mean shoulder height difference after surgery was 7.5 mm (0-11 mm). The admission duration lasted from 8 to 11 days, and the mean duration was 9 days. ④ Follow-up

results:

All patients were followed up in the next 4 years after surgery. The cobb angle correction of major curve remained unchanged, and the instrumented segments were completely fused without instrumentation failure.

CONCLUSION:

Isolated posterior correction using pedicle screw fixation combining with bone grafting and fusion may effectively cure severe and rigid adolescent idiopathic scoliosis, which is considered as Cobb angle of the major curve between 75° and 92° and flexibility ≥ 20%.