Re-Operation Following Primary Posterior Multiple Anchor Instrumentation and Arthrodesis for Idiopathic Scoliosis

Materials and Methods: From 1989 through 2002, 208 consecutive patients, index patient included, age <20 years were operated. Charts and questionnaires reviewed. One hundred ninety-nine (96%) patients followed an average 7 2 months (range, to 16 months) 9 (4%) 11 3 22 months).

Results: Nineteen patients (9.1%) had re-operation: Three (1.4%) peri-operative and unrelated to implants: Eight (3.85%) for pseudarthrosis (3), delayed deep wound infection (2), implant prominence (1), or spondylolisthesis (2; 1 with adjacent de-novo and 1 with peri-adjacent, pre-existing spondylolysis): and Eight (3.85%) for late operative site pain (LOSP). The principle variable affecting re-operation was the transverse connector utilized. From 1989 to October 1995 threaded transverse connectors were utilized in 96 of 98 patients. From October 1995 through 2002 closed drop entry transverse connectors, with 3+ times greater gripping strength, were utilized in 107 of 110 patients. None of the constructs with closed drop entry transverse connectors required re-operation because of LOSP, whereas 8 of the constructs with threaded transverse connectors did, p = 0.0086 (likelihood ratio). Interval to re-operation for LOSP averaged 5 years 11 months; and for lumbar spondylolisthesis the intervals were 11 years 5 months and 15 years 5 months. Both had three mobile lumbar motion segments following their index surgery.

Conclusions: Provision of a stronger transverse connector significantly decreased frequency of re-operation for late operative site pain. We believe this added strength decreased fretting corrosion, the probable cause of late operative site pain. Others have reported that it requires ? 10 years for lumbar spine degeneration and instability below idiopathic scoliosis instrumentation constructs to appear. Long-term follow-up is an indicated part of care.

Kaplan-Meier Estimate: Free from Re-Operation (n=2-8) All Causes