According to the characteristics of the spinal growth and development process, the vertebral epiphyseal cartilage is normally completely fused with the vertebral body around 21 years of age [14]; hence, 21 years of age was defined as the upper age limit for patients with ALDH in this study. However, the lower age limit has not been clearly defined. Raghu et al. [15] reported that LDH patients under 12 years of age were very rare, and the youngest patient in this study was a 10-year-old girl. BMI is one of the commonly used standards for measuring human body fat. A BMI ≥ 28kg/cm2 is used as the diagnostic criterion for obese patients over 18 years of age in our country. However, since adolescents under 18 years of age are still growing and developing, the above criteria for obesity are not suitable for the adolescent population. Therefore, we classified obese adolescent patients according to the obesity classification criteria for adolescents and children under 18 years of age in this study.
Over the past 30 years, obesity has become a global epidemic that threatens public health. The prevalence of obesity and overweight increased by 27.5% in adults and 47.1% in children from 1980 to 2013, and the number of overweight and obese people increased from 921 million in 1980 to 2.1 billion in 2013[16]. The prevalence of obesity in children and adolescents had increased significantly. Numerous studies have suggested that obesity is associated with the incidence of various diseases such as cardiovascular disease, cancer, and bone and joint diseases [17–19], and there is evidence that obesity is also an important risk factors for the onset of ALDH [4, 20]. Obesity applies an excessive load to the intervertebral disc, and it leads to an abnormal inflammatory response and endocrine regulation in the human body, which eventually resulted in accelerated degeneration or damage to intervertebral disc. Obese adolescents accounted for 27.4% of patients with ALDH patients in our study, so we should closely observe obese people with such diseases whether they are adults or adolescents.
spinal surgery in obesity is a challenging endeavor for many reasons, including anesthesia, intravenous access, positioning, and wound exposure. Most spine surgeons would agree that surgical intervention is difficult in this population. Before the emergence of minimally invasive spinal surgery, this group of patients usually required longer surgical incisions than the general population to fully expose the surgical area during lumbar disc herniation, but many complications may occur, including wound infection or poor healing, which affected the surgical satisfaction of these individuals and surgical efficacy [21, 22]. With the development of minimally invasive techniques and the requirement of medical apparatus, PELD has emerged and is widely used in adult and adolescent spinal surgery. Numerous clinical studies have suggested that PELD not only has comparable efficacy compared with conventional spinal surgery, but also has the advantages of reduced blood loss, reduced tissue destruction, and faster postoperative recovery [23–25]. Moreover, several studies [26, 27] have suggested that the application of PELD in obese adults with LDH could reduce the incidence of complications such as wound infection or poor healing. We assume that the decreased incidence of complication in obese patients with PELD can be attributed to technological breakthroughs in the deep surgical field; operations require less time and thus, decrease the chances of contamination and paraspinal muscles trauma. In addition, PELD is usually performed under local anesthesia; therefore, general anesthesia-related adverse events can be avoided effectively. However, no studies have evaluated the efficacy of PELD in obese patients with ALDH.
Compared with adult patients with LDH, patients with ALDH also have the following characteristics. First, the surgical methods is cautiously selected. Regardless of the surgical method used, we need to focus on minimizing the surgical impact on spinal growth and development and the possibility of secondary adjacent segment degeneration or recurrent disc herniation after surgery [28]. Compared with open surgery, PELD minimizes structural damage in the normal spine, such as muscles and facet joints, and reduces the recurrence rate of postoperative iatrogenic instability. Second, the scope of surgical resection is limited. Whether it is PELD or open surgery, the scope of discectomy in adolescents should be controlled to create conditions for the regeneration of intervertebral discs [29] and maximize the retention of the remaining disc function. Finally, it is necessary to consider whether the growth and development of the adolescent spine affects the efficacy of surgery. Gulati et al. [30] believed that the growth of adolescent spine may affect the efficacy of surgery. However, our study showed that in obese or non-obese patients, the excellent and good rate of surgery was more than 93%. Given that PELD is more complicated than traditional open spinal surgery and there may be complications such as residual nucleus pulposus, intraspinal hematoma, infection, and more [31], it often requires a longer learning curve to maximize its performance[32].
Based on the basic characteristics of the two groups before surgery, we found that there were no significant differences in age, sex, history of trauma, segment and type of herniation, severity of preoperative lower back and leg pain, and ODI scores after PSM, so the comparison between the two groups was more reliable. In terms of perioperative data such as operative time, intraoperative blood loss and length of postoperative hospitalization, there was no statistical difference between the obese and control groups (Table 3, P > 0.05), indicating that compared with non-obese patients, obese patients with ALDH may accept PELD without significant difficulties. We believe that because PELD caused less surgical trauma and required no wound drainage tubes, it can effectively shorten the postoperative bedridden recovery time, reduce the occurrence of bed-related complications and hospitalization costs, improve postoperative quality of life, and help patients return to their normal life or work faster, which is in line with the current concept of enhanced recovery after surgery in the field of spinal surgery [33]. However, this was contrary to the results reported in some studies that microdiscectomy or open surgery increased the amount of intraoperative blood loss and length of hospitalization in obese adults [7, 34], indicating that PELD was advantageous in the treatment of obese patients with LDH from the other side.
Based on the main indicators of clinical outcome, the postoperative VAS and ODI scores of both groups were significantly lower than the preoperative scores (Fig. 2, Fig. 3, p < 0.05), and there was no difference in VAS and ODI scores between the two groups at each follow-up time (Table 3, p > 0.05). This indicated that the clinical efficacy of PELD in both obese and non-obese adolescents was comparable, and not affected by obesity. Rihn et al. [6] conducted a 4-year follow-up study of 854 nonobese and 336 obese adults and found that obese patients had less improvement in pain symptoms or postoperative ODI scores than non-obese patients. But the researcher did not clearly explain the surgical method used. Although their results in adults differed from our results in adolescents, it may also suggest that the efficacy of PELD in adolescent patients may not be affected by obesity. From the perspective of minor indicators of clinical outcome, there were no serious complications in either group, and the overall incidence of complications and recurrence rate were not significantly different between the two groups (Table 3, p > 0.05). However, Meredith et al. [35] believed that obesity was a strong and independent predictor of recurrence in patients who underwent lumbar discectomy, which was also inconsistent with our results. We believe that the following two aspects may explain this difference. First, the follow-up time in our study was not sufficiently long, and there was a certain proportion of patients who were lost to follow-up. Second, most adolescents were highly compliant and may adopt more strict postoperative rehabilitation plans under the supervision of their parents. Moreover, the postoperative complications of PELD in our study were mainly manifested as recurring lower back pain or insignificant relief of postoperative pain symptoms, which existed in both the obesity and control groups. However, pain in most patients had little effect on their daily lives or required analgesic intervention. We believe that this finding may be related to abnormal expression of pro-inflammatory cytokines in the blood of patients after surgery or adjacent joint diseases [36, 37].
However, here are some limitations to our study. First, a retrospective single-center study design was used. The number of patients included and the follow-up time were limited, and there were some patients that we could not obtain follow-up data on, which lessened the accuracy of the present cohort. Therefore, a prospective randomized controlled trial with a larger sample size is needed to confirm our results.