Corrective surgery of AIS can result in several benefits for the affected patients including improvements in esthetics, quality of life, disability, back pain, psychological well-being, and breathing function. It also can stop the progression of curve in adulthood, removing the need for further treatments in adulthood . Based on the study of Ward et al., who compared the outcome of 190 non-operatively treated AIS subjects with 166 operatively treated patients, statistically significant differences in self-image, satisfaction, and total score were found in favor of the operative cohort .
On the other hand, AIS surgery still might result in a variety of complications whose long-term impact is poorly understood including neurological damage, loss of normal spinal function, strain on unfused vertebrae, curvature progression, decompensation and increased sagittal deformity, increased torso deformity, delayed paraparesis, and pseudarthrosis [13, 17]. Degenerative disc disease is also considered as one of the late complications of AIS both before and after the surgery, and its association with the severity of pain has been reported .
Thus, the surgeons must carefully weigh the potential for improvement against possible operative or post-operative complications. To this aim, further investigations are needed to shed more light on the long-term complications of AIS surgery and help the surgeon to choose the best therapeutic option.
Here, we evaluated the long-term outcome of PSF surgery in 42 AIS patients at a mean follow-up of 5.6 years. Radiographic markers of significant disc degeneration have been reported in nearly 7% of patients 10 years after surgery for AIS. However, the range of this rate varies between studies . According to our study, new DDD was developed in 6 out of 37 (16%) patients with the preoperative normal discs.
Our study showed no association between the development of DDD and clinical findings (ODI and VAS). Similar results were reported in other investigations [20, 21].
While the DDD was more likely to present at the first post-operative 3–5 years in our patients, the clinical outcome was found to be associated with the time past the surgery, so that an inferior outcome was observed in patients with the longer follow-up period. In other words, the observed post-operative disability tended to increase over the time. The study of Upasani et al. also showed an increased pain at 5 years compared with 2 years after AIS surgical treatment . Thus, we suggest surgeons to discuss this long-term complication with their patients prior to the surgery.
According to the study of Green et al., the lower level of fusion was associated with the higher rate and grade of disc degeneration after PSF surgery of AIS . Similar results were reported by Luk et al. . By contrast, Harding et al. found no correlation between disc degeneration and number of fused vertebrae . Our results were in accordance with the results of Harding et al. .
Our results revealed a significant association between the preoperative vertebral tilt and post-operative ODI. This finding proposes that a pre-operative higher tilt distal to the site of fusion corresponds to a higher post-operative ODI and could be regarded as a prognostic marker of the surgery.
Our study has some weaknesses which should be pointed out. The small number of cases, caused by the high rate of loss of follow-up, could be regarded as the main weakness of this investigation. This limitation might have adversely affected the statistical power of the study. It also did not allow us to further analyze the data, such as to search an association between the grade of DDD and other variables. Thus, further studies with larger sample size are needed to confirm our results.