Abstract
Introduction: Spine disorders are one of the common causes of referral to orthopedic clinics and reasons for orthopedic surgeries. Lumbar spinal surgery helps reduce pain and improve function in patients with certain degenerative conditions. In this paper we investigated the causes of revision spine surgery.
Materials & Methods: In a retrospective cohort study the patients who had undergone revision spinal surgery within one year in a teaching hospital were evaluated -in accordance with diagnosis and clinical criteria. The patients were randomly selected and screened, and demographic information (including age, gender, underlying disease, and body mass index (BMI)) was collected through a data collection form using patients’ records. The clinical features including diagnosis of spine disease, type of previous surgery, number of fusions, history of spine surgery, Roussouly classification, and T-score, and also radiographic parameters such as sagittal vertical angle (SVA), pelvic incidence (PI), lumbar lordosis (LL), PI-LL mismatch, sacral slope (SS) and pelvic tilt (PT) were collected and included in the checklist.
Results & Discussion: The most common cause of original spine surgery was spinal canal stenosis, which was present in 37 patients (92.5%). The most common surgery was discectomy followed by spinal fusion _ performed in 30 (75%) and 27 patients (67.5%) respectively. 25 patients (62.5%) had a history of only one surgery. According to the Roussouly classification, 30 patients (75%) had SS <35 °, and 10 patients (25%) had SS> 35 °. The mean BMI was 28.28. 2.60 kg / m2. The mean T-score in bone densitometry was -1.86 ± 1.06. The mean size of SVA was 7.12 ± 2.19 cm; the mean PI angle was 52.12 ± 10.80 °; the mean LL angle was 23.42 ± 15.56 °; the mean size of the difference between PI and LL angles was 29.25 ± 15.30 °, the mean SS angle was 27.85 ± 10.69 °, and the mean PT angle was 23.62 ± 7.62 °. SVA size was abnormal in 35 patients (87.5%), PI in 14 patients (35%), the difference between PI and LL in 35 patients (87.5%), SS in 34 patients (85%), and PT in 29 patients (72.5%) was abnormal. There was a significant difference in SVA, PI, PI-LL mismatch, SS, and PT between normal and abnormal groups (P-value <0.001).
The patient factors such as old age, previous medical conditions, high BMI, osteopenia, and intraoperative factors, including failure to correct lumbar lordosis, sagittal balance, and correction of angles in primary surgery, showed increased risk for revision spine surgery.
Conclusion: Osteopenia and osteoporosis, failure in reconstituting lumbar lordosis and proper sagittal balance are common reasons leading to revision spine surgery.