SURGERY FOR LUMBAR DISC HERNIATION: OPEN X MINIMALLY INVASIVE TECHNIQUE

ABSTRACT Objective: In Brazil, there are no studies comparing endoscopic treatment of lumbar disc herniation with the conventional open technique in SUS (Unified Health System) with regard to hospitalization time and complications occurring within one year, which is the objective of this study. Methods: A survey of 32 surgeries performed in 2019 (11 open and 21 endoscopic) to evaluate pain parameters before and after surgery (VAS), days of hospitalization, and complications. The data were submitted to statistical analysis (ANOVA) using the Kruskal-Wallis test. Results: Fourteen patients were female and eighteen were male, with a mean age of 41.35 years (p> 0.05 between sexes). The pre- and postoperative VAS for pain radiating to the lower limb were similar between the groups: 8.5 ± 0.82 with the open technique and 8.19 ± 1.15 with endoscopic technique. In both groups there was an improvement in the pain pattern with a significant reduction in the VAS (p < 0.05) and there was no statistical relevance between the groups in terms of pain improvement. There was statistical relevance between the groups in the comparison of days of hospitalization required, with the group submitted to endoscopic surgery having a lower number of days. The complications reported were compatible with those found in the literature (postoperative dysesthesia, new herniation). Conclusions: The endoscopic technique resulted in an important reduction in the number of days of hospitalization, a factor with a high impact on the costs of any surgical procedure, which can be a determining factor in the feasibility of minimally invasive techniques. Level of evidence IV; Therapeutic Study.


INTRODUCTION
Low back pain and sciatica are so common that about 70% of the population may experience them in varying degrees of severity and symptomology at some point in life. 1,2 One of the causes of pain and the main cause of sciatica is disc herniation, which can lead to irritation and compression of the nerve root. The possible treatments for lumbar disc herniation are basically conservative and surgical. Most cases of disc herniation and sciatica can be treated conservatively, leaving only the cases with more serious symptoms and neurological changes to be indicated for surgical treatment. 2 Surgical treatment methods for disc herniation have evolved to be increasingly less invasive while maintaining efficiency or even being superior in terms of the clinical improvement of patients when compared to traditional open approach techniques. 3,4 In addition to the learning curve, 5 another obstacle to greater adherence to minimally invasive techniques is the higher cost of performing this surgical technique as compared to the traditional open technique. The challenge today is trying to balance modern advances in surgical techniques against costs. [6][7][8][9] One of the most widely used minimally invasive treatments for lumbar disc herniation today is endoscopic surgery, 10 already being performed at the Hospital das Clínicas de Ribeirão Preto of the University of São Paulo Ribeirão Preto Medical School (HCFMRP-USP). There are studies that have shown that, although endoscopic surgery for the resection of lumbar disc herniation is more expensive, the savings on hospital stays, medications, earlier return to work, among other factors would compensate for these costs. 11 There are also studies that rate minimally invasive techniques as superior in clinical outcomes than the traditional open technique. 10 The first endoscopic surgeries at HCFMRP-USP were performed in 2018 and consolidated in 2019. The objective of this study was to compare the clinical improvement in those patients submitted to surgical resection of lumbar disc herniation by open and endoscopic techniques in 2019 by evaluating improvement in the level of pain via the visual analog scale for pain (VAS), the number of days of hospitalization required, and complications related to the procedures performed.

METHODS
A survey of the cases operated at HCFMRP-USP (the study center) yielded 32 lumbar disc herniation surgeries performed in 2019 by the HCFMRP-USP spinal orthopedics team, 11 of which were by the open technique and 21 by the endoscopic technique. The parameters of the operated patients analyzed were the levels of preoperative and first postoperative month pain assessed by the visual analog scale for pain (VAS), the number of days of hospitalization required, and any complications related to the procedure that occurred during the first postoperative month. Patients who underwent procedures other than for the resection of disc herniation, or central or foraminal stenosis with or without associated disc herniation, with follow-up less than 1 month following surgery, or younger than 18 years of age were excluded.
The entire survey was conducted by a single researcher, the author, by analyzing pre-and postoperative data from cases operated in 2019 (worksheet of all surgical procedures performed, as well as the mentioned parameters, created annually by the team). Neurological involvement of the cases prior to surgery was not considered; the indication of all cases involved pain refractory to conservative treatment.
The study was submitted to and approved by the institutional review board with the required authorization to waive the application of the informed consent form (CAAE: 34002020.7.0000.5440, opinion number 4.137.682).
Statistical analysis of the collected data was conducted using ANOVA analysis of variance through the Kruskal-Wallis test.

RESULTS
Of the 32 patients selected, 14 were female and 18 were male with a mean age of 41.35 years. Eleven surgeries were performed using the open technique, with only two for herniation in segment L3-L4, and all the others in L4-L5 or L5-S1. There were 21 patients in the group that underwent endoscopic surgery, with only one in segment L3-L4 and the rest in L4-L5 or L5-S1. There was no statistical difference in relation to age between the two groups (p=0.52). The distribution of the patients by technique performed, sex, and age is shown in Table 1.
In the open technique surgery patient group the mean preoperative VAS for pain radiating to the leg was 8.5 with a drop to a mean of 1.9 in the postoperative period, a statistically significant improvement (p<0.0001) in the radiating pain pattern. A mean of 1.81 days in the hospital were necessary and 2 cases presented complications, one with reherniation of the same level less than 1 month after surgery and one case of dysesthesia at the root of the level affected by the herniation.
In the endoscopic surgical technique group, the mean preoperative VAS for leg pain was 8.2, improving to a mean of 2.5 in the postoperative period. There was also a statistically significant improvement (p<0.0001) in the pattern of radiating pain. A mean of 0.76 days in the hospital were necessary and, in 3 cases, surgical reapproach was required for a remaining herniation fragment with persistent intense pain, with pain improvement following the reapproach. In 6 other cases, we had postoperative dysesthesia at the root of the affected level.
In the comparison between the groups, there was no statistical significance between either the preoperative or postoperative VAS, with p=0.37 and p=0.69, respectively. (Table 2) Therefore, we had similar improvement in the patterns of radiating pain in the two techniques performed. The comparison of the days of hospitalization required showed statistical significance with p=0.0016. Therefore, the endoscopic technique required less hospitalization time, which may correspond to a source of savings in the final cost of the surgery.

DISCUSSION
Lumbar disc herniation is a frequent pathology in the population and in some cases surgical treatment is necessary. 2 The evolution of surgical treatments for disc herniation has been focused on increasingly more minimally invasive approaches in search of clinical results associated with faster recovery. 9 One of the minimally invasive techniques on the rise in Brazil is the percutaneous endoscopic technique. The disadvantage of minimally invasive treatments is the higher cost of the surgical procedure. There are still few studies that evaluate the real costs of open surgery and endoscopic surgery for lumbar disc herniation. The philosophy of the minimally invasive technique would be to maintain clinical results associated with faster recovery and shorter hospitalization time.
Within its natural evolution, the spinal surgery service of the HCFMRP-USP orthopedics department has sought this advance in the treatment of lumbar disc herniation with the implementation of endoscopic surgery. As expected, we obtained similar results between the open and endoscopic techniques, with a significant reduction in the length of the hospital stay in the latter, a factor that contributes to a reduction in overall costs. The complications encountered are in accordance with the literature and there was no statistical relevance.

CONCLUSION
In general, patient satisfaction was very good and their treatment highly praised.
One of the obstacles and difficulties of the endoscopic technique other than the higher overall cost is the long learning curve. 5