Results of Anterior Instrumentation for Adolescent Idiopathic Scoliosis

Istanbul Medical Faculty, Dept. of Orthopaedics and Traumatology, Istanbul, Turkey

OBJECTIVES: To review the charts and radiographs of patients with adolescent idiopathic scoliosis who underwent anterior correction and fusion with rigid single rod third generation instrumentation and titanium mesh cages and to analyze their coronal and sagittal plane corrections, spontaneous secondary curve corrections, balance, number of fused segments and saved lumbar levels, complications and early follow-up results.

PATIENTS AND METHODS: 32 patients with a mean follow-up of 31months (range 24 - 45 months) were included in this study. Mean age was 14.9 years. There were 8 patients with King Type I, 10 with Type II, 6 with Type III, 4 with Type IV and 4 with lumbar curves. Titanium mesh cages were used in all lumbar procedures and at the cranial and caudal ends of the instrumented area in thoracic cases. After giving the proper sagittal contour, the rod was first fixed to the most distal segment and then correction was achieved by performing translation with cantilever maneuver. In thoracic curves mesh cages were especially used for the upper one or two disc spaces in order to prevent pull-out of the most proximal screw and junctional kyphosis above instrumentation. All patients were immobilized in an orthosis for 3 to 6 months postoperatively. Pre-operative, post-operative and follow-up radiographs were reviewed.

RESULTS: Mean pre-operative primary coronal Cobb angle of 51° was improved to 8.6°. Average correction rate was 83.9%. Sagittal balance was also restored to a mean thoracic kyphosis of 27.5° and a mean lumbar lordosis of 37.6°. Spontaneous secondary curve decompensation never occurred. Mean number of lumbar levels saved in comparison to posterior surgery was calculated as 0.93. Thoracolumbar junctional kyphosis after surgery was not seen. Loss of correction, non-union and implant failure did not develop except in one case who had anterior thoracic curve correction and was revised with posterior surgery and instrumentation for the most proximal screw pull-out.

CONCLUSION: Our early results dictate that anterior correction using 3. generation single solid rod instrumentation in combination with titanium mesh cages offers a good alternative to posterior instrumentation and provides some advantages like better axial and sagittal plane correction, fusing shorter segments, avoiding secondary curve decompensation and also obtaining a better cosmesis.