Adult Scoliosis: A Retrospective Analysis of the Correlation between Radiological Parameters and Clinical Outcomes

Background: According to current literature, surgical management of Adult Scoliosis (AS) can benefit selected patients, especially when concurrent sagittal deformities are balanced. This retrospective study analyzes this hypothesis by matching clinical and radiological results after AS surgical correction in selected cases. The study also analyzes the possible correlation between mechanical failure events and residual postoperative sagittal imbalance. Materials and Methods: 12 patients, average aged 57 years, underwent AS surgical correction. Today, these patients have a follow up range from 24 months to 71 months (average 53.6 months). Values related to scoliotic curve, lordosis, kyphosis and pelvic parameters (Pelvic Incidence, PI; Pelvic tilt, PT; Sacral Slope, SS; Sagittal Vertical Axis, SVA) were measured and registered pre-operatively and post-operatively. Patients were examined at 3, 6, and 12 months after surgery and then every year through outpatient visits, where the degree of patient satisfaction was evaluated. Patients also received before the surgery and at 3, 6, 12 months follow up auto-administered validated questionnaires (Visual Analog Score, Oswestry Disability Index, Quality of Life) for the evaluation of clinical outcomes. Regarding patients’ responses to these questionnaires we have a follow up range of 3-20 months (average 8.4 months). Mechanical failure complications were also registered during the entire follow up period. Results: Radiological results: scoliosis was corrected on average 27°; kyphosis changed in 10 patients, by an average increase of 11.33° in 6 patients and by an average reduction of 12.7° in 4 cases. The average correction of lordosis, compared to an ideal reference value, was 61.94% (41.89 – 86.42%). A pathological pelvic retroversion (PT>20°) affected 10 patients out of 12. After surgery this compensation vanished in 3 patients while it remained >20° in 7. Postoperative plumb line analysis showed that only five patients had a balanced postoperative profile. Clinical results: Improvement of clinical conditions and patient’s satisfaction were obtained in 9 out of 12 patients. Mechanical Failure: in our series, 4 patients (33%) experienced hardware failure. Statistical analysis was performed using Kendall’s correlation test and Pearson’s correlation test. Conclusions: This retrospective study evaluates medium and long term adult scoliosis surgical results, by matching clinical outcomes and postoperative balance. The complete rescue of physiological balance was demonstrated to reduce disability in all cases except one; according to our experience, also a partial reduction of the deformity could improve the clinical patient’s condition, especially in cases where deformity and disability were severe before the surgery. Statistically analysis showed a correlation between kyphosis changes following surgery and clinical outcomes trend. Despite the small sample size, we also observed that residual imbalance favored early mechanical hardware failure, confirming the trend reported in the literature.