DOES INSTRUMENTED ANTERIOR SCOLIOSIS SURGERY LEAD TO KYPHOSIS, PSEUDARTHROSIS OR INADEQUATE CORRECTION IN ADULTS?

Jason A. Smith, M.D.,
Vedat Deviren. M.D.,
Arash Emami, M.D.,
Sigurd Berven, M. D.,
David S. Bradford, M.D.

INTRODUCTION:
Anterior spinal fusion (ASF) for the treatment of spinal deformity has advantages including better control of rotation, improved overall correction, and fewer levels of fusion. Although some reports have demonstrated a high fusion rate in adults with ASF, recent reports have shown an extremely high rate of pseudarthosis as well as hardware failure even in adolescents who have undergone ASF with instrumentation. We therefore undertook a retrospective review of the radiographic and clinical outcome in adult patients who had undergone ASF with the use of a single rigid rod for thoracolumbar or lumbar idiopathic scoliosis.

MATERIAL AND METHODS:
Fifteen consecutive adult patients, average age 37.5 years (range 25 to 59) had undergone ASF with a rigid rod by a single surgeon. The indications for surgery were back pain and progression of deformity. One was lost to follow–up, leaving 14 patients with complete radiographic and clinical follow–up of 34 months (range 24 to 65 months). Patients were sent the SRS Outcomes Instrument, charts were reviewed, and pre– and post–operative long–standing films of the spine were evaluated. Fusion levels were typically Cobb to Cobb, though the fusion was shortened if possible when bending films showed flexibility above the stable vertebrae. Based on the stable vertebrae on bending and erect AP films, the number of levels “saved” as a result of anterior vs. posterior fusion was calculated.

RESULTS:
The average pre–operative major curve was 50 degrees (41 to 69), which improved to 17 degrees (5 to 35) post–operatively, a 66 % correction. The average correction of the upper compensatory curve and lower fractional curve were 49% and 61%, respectively. The sagittal plane alignment was either maintained or improved in all patients, demonstrating that surgery did not induce kyphosis in any patient. Coronal and sagittal plane balance was either achieved or maintained in all patients. On average 1.2 levels were saved (range 0–2) with anterior surgery. Follow–up Modified SRS Outcome Instrument revealed satisfaction score of 4.6 out of possible score of 5, pain score 4.4, self–image 4.0, function 4.2, and mental health 4.1, with a grand total score of 82 %. All patients but one were satisfied or extremely satisfied with the results of surgery. There was no incidence of hardware breakage, and all patients achieved a solid fusion. There were two minor and two major complications postoperatively. There were no permanent neurologic deficits.

CONCLUSIONS:
The results of anterior spinal fusion using a single solid rod in adults with idiopathic scoliosis are excellent, with 100% fusion rate, no development of kyphosis, and no incidence of hardware failure. The primary curve was corrected 66%, and balance was maintained. An average of 1.2 levels was saved relative to the stable vertebra. Fourteen of fifteen patients are either satisfied or extremely satisfied with the outcome of surgery.