Risk factors for prolonged length of stay after first minimally invasive tubular microdiscectomy in lumbar disc herniation

Risk factors for prolonged length of stay after first minimally invasive tubular microdiscectomy in lumbar disc herniation | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Risk factors for prolonged length of stay after first minimally invasive tubular microdiscectomy in lumbar disc herniation Xin Wang, Lu Tian, Feng Li This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7910953/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background This study was to identify potential risk factors for prolonged length of stay (LOS) in patients with lumbar disc herniation (LDH) after first minimally invasive tubular microdiscectomy (TMD). Demographic data, clinical records, and imaging studies were retrospectively analyzed in this study. The primary outcome was defined by the total number of days stayed at hospital. A prolonged LOS was defined as ≥ 1 day beyond the median hospital stay in our patient cohort. Bivariate analysis and multivariate regression, as well as correlation analysis were conducted to investigate the risk factors for prolonged LOS. Results A total of 111 patients who underwent TMD were consecutively included in our study. Statistical analysis of potential factors influencing LOS was performed for 24 variables independently, in which five variables significantly related to a prolonged LOS in bivariate analysis were carried into multivariate regression. Coronary heart disease, nucleotomy, and anticoagulation/antiplatelet agents were treated as binary variables, whereas age at surgery and surgical duration were treated as continuous variables. After logistic regression analysis, only surgical duration (p = 0.018) was identified as an independent predictive factor for prolonged LOS. Finally, the Spearmen correlation analyses indicated that there were significant positive correlations between surgical duration and the prolonged total and postoperative LOS (p ˂ 0.005). Conclusions Our study indicated that surgical duration was a significant risk factor for prolonged hospital stay. Further studies are needed before firm conclusions can be established. lumbar disc herniation tubular micro-discectomy risk factor length of stay Figures Figure 1 Background Lumbar disc herniation (LDH), the most common lumbar degenerative disease, could result in severe lumbosacral radicular syndrome and sciatica, which causes considerable socioeconomic burden [ 1 – 3 ]. For patients with serious radicular manifestations, micro-invasive surgery is recommended if patient failed to benefit from conservative treatment [ 2 , 3 ]. In the lumbar micro-discectomy, degenerative and pathological intervertebral disc materials are removed to decompress the nerve root, thus the pain could be relieved [ 4 ]. In the USA alone, nearly $ 50 billion annually were spent on spinal disorders [ 5 ]. Meanwhile, lumbar surgery and the relative hospital stay account for an enormous cost of the health care system annually [ 5 , 6 ]. Extended length of stay (LOS) increase the risk of postoperative complications such as limb vein thrombosis or hospital infection [ 5 – 7 ]. Thus, identifying risk factors that potentially prolong the hospital stay is essential for improving efficient patient care and economizing the medical and health resources. Compared with the conventional micro-discectomy (CMD), the application of minimally invasive tubular retractor system has greatly decreased the extent of surgical trauma [ 8 ]. The commination of tubular retractors and endoscopes was first used in the micro-endoscopic discectomy by Foley and Smith in 1997 [ 8 ], followed by the conjunction of tubular retractor systems with microscopes to improve the working scope in 2002 [ 8 ]. In stead of dissecting the subperiosteal muscle, a muscle-space approach is usually utilized in tubular micro-discectomy (TMD), thus tissue injuries are decreased. Nowadays, TMD has already been a developed spinal surgical technique for LDH [ 9 – 12 ]. Previous studies have investigated the potential risk factors for prolonged hospital stay after open lumbar surgery [ 5 – 7 ]. However, to our knowledge, there is a lack of studies that aimed specially at LDH patients who underwent the first TMD. Therefore, this preliminary study was to investigate the potential factors that prolong the hospital stay for LDH patients after the first TMD. Methods Patient with LDH who underwent minimally invasive TMD at XXX from March 2021 to July 2024 were included in this retrospective study. The diagnosis of LDH was validated based on the physical presentations, and typical radiological evidence. The patients complained of severe radicular pain, and obvious physical functional impairment in spite of optimal medical treatment prior to surgery. None of the patients had surgical contradictions such as severe cardiovascular diseases. LDH patients who underwent a second TMD or open conventional discectomy were excluded. Patients with incomplete clinical data were also excluded. Finally, 111 LDH patients (54 men and 57 women) with complete clinical data were included in our study. This study was approved by the local ethics committee of the XXX. Written informed consent was signed by each patient prior to the surgery. Preoperative examinations include basic hematologic tests, electrocardiogram, chest radiographic examination, as well as echocardiogram and lung function test if necessary. In addition, patient underwent lumbar spine MRI, three-dimensional (3D) CT, as well as X-ray scanning. The CT 3D construction images could present the practitioner with a direct visualization of the integral bone structure. General anesthesia was induced on the day of surgery. A prone position was taken, followed by an intraoperative CT to identify the target intervertebral space with the herniated disc. A 1.5 ~ 2.0 mm-long paramedian incision about 3.5 cm off the midline was made based on the center of the target intervertebral space. A tubular retractor system was docked against the angle of the spinous process and vertebral plate at the same level and ipsilateral to the herniated disc. If necessary, intraoperative CT imaging was performed a second time to validate the exact placement of the tubular retractor system. After the placement of the 14- or 18-mm diameter tubular retractor, microscope was brought in, followed by the partial hemi-laminotomy and excision of the underlying ligamentum flavum to expose the underlying impinged nerve root. Resection of the nucleus pulposus was performed if the herniated disc heavily compressed the nerve root. The impingement on nerve root was relieved satisfactorily, and deep fascia and the subcuticular layer were closed with absorbable sutures. No subcutaneous drainage tube was placed if no dural tear happened during the surgical procedure. After surgery, patient was guided to perform “straight leg raising exercises” on bed followed by out-of-bed activities with waist support 2–3 days postoperatively. If no complications happened, patients would be discharged after a postoperative lumbar spine 3D-CT imaging. Basic demographic, clinical data, and imaging findings of each patient was acquired through the retrieval of the HIS Medical Record System. Basic demographic data included name, age, and sex. Clinical data included disease duration, comorbidities, the level and side of the disc herniation, and comorbidities. Perioperative variables mainly included surgical duration, resection of nucleus pulposus and dural tears. In this study, surgical duration refers to the time interval from anesthesia induction to leaving the operation room. Postoperative items mainly consist of the total length of stay and length of stay after surgery. Severity of the radicular pain was assessed using Visual Analog Scale (VAS) at baseline and 1 day before discharge. All the clinical assessment were performed by our practitioners ( ). In this study, a total of 24 potential relevant clinical factors were selected. A complete listing of the above factors was presented in Table 1 and Table 2 . The factors “additional LDH” and “spinal stenosis” refer to lesions at levels other than the one being operated [ 5 ]. Table 1 Comparisons of the binary factors between the two groups Factor No Binary Factors Normal LOS Group (n = 59) Prolonged LOS Group (n = 52) p Value X1 Sex (male/female) 27/32 27/25 0.517 X2 Preoperative immobility (yes/no) 24/35 29/23 0.112 X3 Side (left/right) 25/34 27/25 0.314 X4 Preoperative paresis (yes/no) 27/32 21/31 0.568 X5 Hypertension (yes/no) 17/42 16/36 0.822 X6 Diabetes mellitus (yes/no) 10/49 8/44 0.823 X7 Coronary disease (yes/no) 3/56 10/42 0.035 X8 Hypothyroidism (yes/no) 2/57 1/51 0.634 X9 Lasegue sign (yes/no) 30/29 26/26 0.929 X10 Smoking (yes/no) 9/50 7/45 0.788 X11 Drinking (yes/no) 9/50 4/48 0.216 X12 Spinal stenosis (yes/no) 48/11 43/9 0.855 X13 Single-level operation (yes/no) 55/4 45/7 0.240 X14 Additional LDH (yes/no) 39/20 39/13 0.306 X15 Drainage (yes/no) 2/57 2/50 0.898 X16 Nucleotomy (yes/no) 35/24 21/31 0.046 X17 Dural tears (yes/no) 2/57 2/50 0.898 X18 Far lateral LDH (yes/no) 4/55 5/47 0.585 X19 Hyperlipidemia (yes/no) 15/44 7/45 0.115 X20 Anticoagulation/antiplatelet agents (yes/no) 0/59 4/48 0.030 Boldface type indicates statistical significance Table 2 Comparisons of the continuous factors between the two groups Factor No Continuous Factors Mean ± SD (range) Normal LOS Group (n = 59) Prolonged LOS Group (n = 52) p Value X21 Age at surgery, years 55.1 ± 12.9 61.8 ± 14.1 0.003 X22 Disease duration, months 35.2 ± 75.8 37.7 ± 76.0 0.854 X23 VAS scores at baseline 7.3 ± 0.9 7.5 ± 0.8 0.319 X24 Surgical duration, minutes 145.5 ± 52.9 176.2 ± 56.9 0.000 Boldface type indicates statistical significance As indicated in the previous study, a prolonged length of stay (LOS) was defined as ≥ one additional day beyond the median hospital stay in our patient series. In this study, LOS referred to the total number of days the patients stayed in hospital. Readiness to be discharged from the hospital was determined by the surgeons ( ), based on the actual conditions of the patients including pain relief (VAS scores), and sufficient mobility. Patients were divided into prolonged LOS group and normal LOS group. Twenty-four clinical factors, labeled X1-X24, were assessed for each group. The outcome was encoded as the variable Y, with Y = 0 representing normal LOS, and Y = 1 representing prolonged LOS. In the first step for bivariate analysis, each clinical variable was compared between these two groups. If significant difference existed for a variable, it would be carried over to the second step for further analysis; otherwise, this variable was excluded. In the second step, the surviving factors were brought into a binary logistic regression model. Chi-square test or Fisher’s exact test was performed to compare the binary variables, such as sex, smoking, and dural tears. The Mann-Whitney U -test was used to compare continuous variables with non-normal distributions, while two-sample t test was performed to compare the continuous variables with normal distributions. Continuous variables are presented as mean ± SD (range). A value of P ˂ 0.05 was recognized as statistically significant. Statistical analyses were performed with SPSS software (Version 23.0, IBM, Armonk, NY). All of the statistical analyses were performed by an experienced statistician ( ). Results In the 111 LDH patients (54 men and 57 women) included in our study, mean age at surgery was 58.3 ± 13.8 (range, 18–80) years, mean disease duration before surgery 36.4 ± 75.6 (0.03–480) months, total length of stay 11.1 ± 3.8 (6.0–28.0) days, and postoperative length of stay 7.5 ± 2.7 (4–24) days. Median LOS was 10 days, thus 52 and 59 patients were divided into prolonged and normal LOS group respectively. In the first step for bivariate analysis, 20 binary variables (Table 1 ) and 4 continuous variables (Table 2 ) were compared between the two groups individually. Significant differences existed for 5 variables: coronary heart disease (X7, yes vs no), nucleotomy (X16, yes vs no), anticoagulation/antiplatelet agents (X20, yes vs no), age at surgery (X21) and duration of surgery (X24), and these variables were carried forward into the next step for multivariate analysis. As is seen in Table 2 , age at surgery was significantly different between the two groups (55.1 ± 12.9 vs. 61.8 ± 14.1, p = 0.003). Other basic factors, including sex (X1), side (X3), smoking (X10), drinking (X11) and disease duration (X22), did not show significant between-group differences (p ≥ 0.05, Table 1 ). As for the preoperative items, statistical between-group differences existed in the factors “coronary heart disease” (p = 0.035) and “anticoagulation/antiplatelet agents” (p = 0.030). However, other preoperative items, including preoperative immobility (X2), preoperative paresis (X4), hypertension (X5), diabetes mellitus (X6), hypothyroidism (X7), Lasegue sign (X9), hyperlipidemia (X19) as well as VAS scores at baseline (X23), did not show significant difference between the groups (p ≥ 0.05). Radiological variables, such as spinal stenosis (X12) and additional LDH (X14) were also similar between the two groups. With regard to the variables related to surgery, there was significant between-group difference in the item of “nucleotomy” (p = 0.046). Besides, surgical duration was significantly different between the two groups (145.5 ± 52.9 vs. 176.2 ± 56.9, p ˂ 0.001). Other surgical variables, such as single-level operation (X13), drainage (X14), and dural tears (X15) were balanced between the two cohorts. Therefore, the five significant variables (X7, X16, X20, X21, X24) found in bivariate analysis were then included in a logistic regression model for multivariate analysis. In the regression model, X7, X16, and X20 were treated as binary variables, while X21 and X24 were treated as continuous variables. As indicated in Table 3 , surgical duration (p = 0.018, OR 1.010, 95% CI 1.002–1.109) was the only risk factor of prolonged LOS for LDH patients with TMD, indicating patients with longer surgical duration were more likely to postpone discharging after surgery. Finally, the Spearmen correlation analyses indicated that there were significant positive correlations between the surgical duration and the prolonged total (Spearman’s rho = 0.321, p = 0.001, Fig. 1A) and postoperative LOS (Spearman’s rho = 0.269, p = 0.004, Fig. 1B). Table 3 Multivariate logistic regression analysis of prolonged length of stay Variables p value OR 95% CI β Wald SE Coronary disease 0.313 2.217 0.472–10.416 0.796 1.107 0.789 Anticoagulation/antiplatelet agents 0.999 6.055E8 0.000-+∞ 20.222 0.000 19976.922 Nucleotomy 0.158 0.540 0.230–1.269 -0.615 1.997 0.435 Age at surgery 0.248 1.019 0.987–1.053 0.019 1.336 0.017 Surgical duration 0.018 1.010 1.002–1.109 0.010 5.593 0.004 Boldface type indicates statistical significance Discussion To the best of our knowledge, this is the first study to investigate the potential factors that prolong the hospital stay for LDH patients after the first TMD. A total of 24 variables were selected and evaluated, five of which exhibited significant between-group differences in the bivariate analysis. Surgical duration remained as the only independent risk factor for prolonged LOS after logistic regression analysis. Furthermore, the Spearmen correlation analyses indicated that there were significant positive correlations between surgical duration and the prolonged total and postoperative LOS. Surgical methods for LDH include traditional open midline or paraspinal approach, transforaminal endoscopic techniques, as well as TMD [ 2 , 3 , 8 , 11 – 14 ]. Conventional open surgery via midline or paraspinal approach usually performs extensive paraspinal muscles detachment, partial or total facetectomy. It thus increases the risk of tissue injury, spinal instability, and causes heavier burden on the patients [ 9 , 12 , 15 ]. As for the endoscopic surgery, practitioners operate with the assistance of the endoscope, but might be limited by the high requirement of controlling the endoscope, and difficulty in stop bleeding [ 16 ]. The microscope, instead of the endoscope, in combination with the tubular retractor systems, presents the practitioners with a more sufficient three-dimensional view, and thus improved the operative flexibility [ 9 , 12 , 15 ]. Ritter and colleagues [ 5 ] investigated the risk factors for a prolonged LOS after conventional lumbar micro-discectomy; in that study, duration of surgery was treated as a categorical variable, and there was no significant effect in the bivariate analysis. Our study investigated risk factors for a prolonged LOS after TMD, and indicated that patients with longer surgical duration were more likely to postpone discharging. This controversy might be interpreted with the differences in the surgical techniques and data processing method. Compared with the conventional open surgery, duration of surgery is a reflection of operative difficulty and surgeon’s proficiency in a higher extent. It requires longer time and more meticulous manipulations in the operation on patients with more severe nerve root impingement and tissue adhesion. Besides, surgical duration was treated as a continuous variable directly in our study. Our results also emphasized the importance of improving the proficiency of the surgeon himself. However, our result must be interpreted with caution, and further studies are needed before a firm conclusion could be established. Several previous studies have investigated the effects of demographic variables such as age on the LOS after lumbar micro-discectomy, and the results were not consistent. Khanaan and colleagues [ 17 ] suggested that a higher age was correlated with longer LOS, and explained this correlation as a consequence of more preoperative comorbidities and postoperative complications. However, in the study of Ritter and colleagues [ 5 ], age ˃ 65 years was significantly correlated with LOS, but age was an insignificant factor in the multivariate analysis. In our study, age, sex, as well as smoking, and drinking were balanced between the two groups and were not correlated with prolonged LOS. As for the comorbidities, diabetes mellitus was recognized as a significant risk factor associated with prolonged LOS after lumbar spine surgery in several previous studies [ 18 , 19 ]. Maloney and colleagues [ 18 ] indicated a longer LOS in diabetic population who underwent open lumbar surgery, which is consistent with the study result by Guzman and colleagues [ 20 ]. However, in our study, diabetes mellitus was not a significant risk factor even in the bivariate analysis. This might be explained by the optimal glycemic control in perioperative period at our center. Similarly, there were also no significant between-group differences in hypertension, hypothyroidism, or hyperlipidemia. Coronary disease was significant in bivariate analysis; however, multivariate regression analysis indicated that it was not an independent risk factor for prolonged LOS after TMD. Regarding the preoperative medication, there were significant between-group difference in the exposure to anticoagulation and/or antiplatelet medication. In the multivariate regression analysis, this factor did not remain to be a potential risk factor for prolonged LOS. As indicated in the study of Ritter and colleagues [ 5 ], this variable might be more of a confounding factor than an independent risk factor for LOS, because patients exposed to anticoagulation and/or antiplatelet medication were usually older than individuals who did not. As for the preoperative clinical conditions, bivariate analysis showed no significance in preoperative immobility, paresis, Lasegue sign, and spinal stenosis. A previous study identified preoperative immobility as an independent risk factor for prolonged LOS after single-level lumbar microdiscectomy [ 5 ]. In our study, most patients with immobility preoperatively were capable of walking within days after TMD. Besides, in the preoperative evaluations, far lateral lumbar disc herniation (FLLDH) was regarded as a separate disc pathological category that required to be cautioned. FLLDH, including intraforaminal and extraforaminal lumbar disc herniation, is the herniation that occurs outside the lumbar spinal canal [ 21 ], comprising 3–12% of all lumbar disc herniations [ 22 – 24 ]. The herniated disc compresses the exiting nerve root and dorsal root ganglion, resulting in extreme and refractory pain [ 21 , 22 ]. Clinical manifestations of FLLDH differed from medial disc herniation at the same spinal level, instead they resemble those of the medial disc herniation at one lower spinal segment. In the surgical treatment of FLLDH, TMD utilizes a muscle-space approach instead of dissecting subperiosteal muscle dissection, reducing the tissue damage, and shortening the postoperative recovery period [ 24 ]. Thus, in our study, FLLDH was not a predictive factor for prolonged LOS after TMD. In the surgical procedures, resection of the nucleus pulposus was performed if the herniated disc protruded obviously and heavily compressed the nerve root. In our study, normal LOS group had a significant larger proportion of individuals undergoing nucleotomy than prolonged LOS group. However, the final regression model indicated that it was not a predictive factor for LOS. This results was consistent with the previous study of Ritter and colleagues [ 5 ]. Similarly, the ratio of dural tear and drainage were balanced between the groups, and they were not significant factors in our analysis. As mentioned earlier, surgical duration was positively correlated with LOS, thus several details should be mentioned to shorten the surgical time while improve the efficacy. Firstly, the herniated disc segmented being operated on should be precisely located based on preoperative radiology, anatomical landmark, and intraoperative CT. Secondly, the incision was 1.5 to 2.0 cm, avoiding to be too narrow or longer than necessary, followed by the blunt dissection using index finger and optimal placement of the tubular retractor systems. Thirdly, carefully preserve the paravertebral venous plexus and dural sac throughout the surgery. Finally, hydrogen peroxide and iodine irrigation was suggested before closing the incision. Our study identified the potential risk factors for prolonged LOS after TMD, based on a relatively large sample size. The operations were finished by the same experienced senior surgeon, minimizing the confounding effects. In addition, we summarized the standardized process of TMD, and over 95% of the patients benefited from this surgical technique ultimately (data not shown). However, several limitations also need to be mentioned. Firstly, our study was limited by the inherent nature of its respective design. Besides, this study focused on the hospital stay, therefor the long-term clinical outcomes warranted to be evaluated in the further studies. Conclusions In conclusion, the present study indicated that surgical duration was a significant risk factor for prolonged hospital stay, and patients with longer surgical duration were more likely to postpone discharging after surgery. However, our results should be interpreted with caution. A larger and well-designed prospective trial are also recommended before the final establishment of the conclusion. Abbreviations LDH, lumbar disc herniation VAS, Visual Analog Scale TMD, tubular micro-discectomy CMD, conventional micro-discectomy LDH, length of stay FLLDH, far lateral lumbar disc herniation Declarations Author Contribution All authors contributed to the study conception and design. X.W wrote the main manuscript text, performed the statistical analyses, and prepared figures. L.T performed the statistical analyses, and prepared tables. F.L reviewed the manuscript. All authors read and approved the final manuscript. Data Availability The data used to support the findings of this study are available from the corresponding author upon request. References Thavarajasingam SG, Salih A, Arif A, Varadpande M, Sabeshan P, Ponniah HS, et al. Indications for surgery versus conservative treatment in the management of lumbar disc herniations: A systematic review. Brain Spine. 2025;5:105619. Chen Y, Lin F, Wang K, Chen F, Wang R, Lai M, et al. 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10:22:44","extension":"xml","order_by":7,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":78144,"visible":true,"origin":"","legend":"","description":"","filename":"194eedfa8b1f42ac9ed011ef1ff1e8871structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-7910953/v1/1dc6b1acd28e838e7269939c.xml"},{"id":96616185,"identity":"aa4ba8c4-59d8-457c-b82d-1aa48c92cddb","added_by":"auto","created_at":"2025-11-24 10:22:44","extension":"html","order_by":8,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":84229,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7910953/v1/41d35bce1ce6a647b9483a3e.html"},{"id":96616176,"identity":"bdbc0da1-0328-40ef-b810-00d5795ed636","added_by":"auto","created_at":"2025-11-24 10:22:44","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1390633,"visible":true,"origin":"","legend":"\u003cp\u003eSurgical duration correlated with total and postoperative length of stay.\u003c/p\u003e\n\u003cp\u003eA: Total length of stay versus surgical duration. Spearman’s rho = 0.321, p = 0.001\u003c/p\u003e\n\u003cp\u003eB: Postoperative length of stay versus surgical duration. Spearman’s rho = 0.269, p = 0.004\u003c/p\u003e","description":"","filename":"Figure1.png","url":"https://assets-eu.researchsquare.com/files/rs-7910953/v1/cfb85b0293d369e568aba3f6.png"},{"id":101942701,"identity":"0b6f6577-f491-46c9-b2b5-de1a572c1040","added_by":"auto","created_at":"2026-02-05 09:34:25","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1720937,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7910953/v1/e1bfbff1-dc40-4fdd-af44-15516235553c.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Risk factors for prolonged length of stay after first minimally invasive tubular microdiscectomy in lumbar disc herniation","fulltext":[{"header":"Background","content":"\u003cp\u003eLumbar disc herniation (LDH), the most common lumbar degenerative disease, could result in severe lumbosacral radicular syndrome and sciatica, which causes considerable socioeconomic burden [\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. For patients with serious radicular manifestations, micro-invasive surgery is recommended if patient failed to benefit from conservative treatment [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. In the lumbar micro-discectomy, degenerative and pathological intervertebral disc materials are removed to decompress the nerve root, thus the pain could be relieved [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eIn the USA alone, nearly \u003cspan\u003e$\u003c/span\u003e50\u0026nbsp;billion annually were spent on spinal disorders [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Meanwhile, lumbar surgery and the relative hospital stay account for an enormous cost of the health care system annually [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Extended length of stay (LOS) increase the risk of postoperative complications such as limb vein thrombosis or hospital infection [\u003cspan additionalcitationids=\"CR6\" citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Thus, identifying risk factors that potentially prolong the hospital stay is essential for improving efficient patient care and economizing the medical and health resources.\u003c/p\u003e\u003cp\u003eCompared with the conventional micro-discectomy (CMD), the application of minimally invasive tubular retractor system has greatly decreased the extent of surgical trauma [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. The commination of tubular retractors and endoscopes was first used in the micro-endoscopic discectomy by Foley and Smith in 1997 [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e], followed by the conjunction of tubular retractor systems with microscopes to improve the working scope in 2002 [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. In stead of dissecting the subperiosteal muscle, a muscle-space approach is usually utilized in tubular micro-discectomy (TMD), thus tissue injuries are decreased. Nowadays, TMD has already been a developed spinal surgical technique for LDH [\u003cspan additionalcitationids=\"CR10 CR11\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Previous studies have investigated the potential risk factors for prolonged hospital stay after open lumbar surgery [\u003cspan additionalcitationids=\"CR6\" citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. However, to our knowledge, there is a lack of studies that aimed specially at LDH patients who underwent the first TMD.\u003c/p\u003e\u003cp\u003eTherefore, this preliminary study was to investigate the potential factors that prolong the hospital stay for LDH patients after the first TMD.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003ePatient with LDH who underwent minimally invasive TMD at XXX from March 2021 to July 2024 were included in this retrospective study. The diagnosis of LDH was validated based on the physical presentations, and typical radiological evidence. The patients complained of severe radicular pain, and obvious physical functional impairment in spite of optimal medical treatment prior to surgery. None of the patients had surgical contradictions such as severe cardiovascular diseases. LDH patients who underwent a second TMD or open conventional discectomy were excluded. Patients with incomplete clinical data were also excluded. Finally, 111 LDH patients (54 men and 57 women) with complete clinical data were included in our study.\u003c/p\u003e\u003cp\u003e This study was approved by the local ethics committee of the XXX. Written informed consent was signed by each patient prior to the surgery.\u003c/p\u003e\u003cp\u003ePreoperative examinations include basic hematologic tests, electrocardiogram, chest radiographic examination, as well as echocardiogram and lung function test if necessary. In addition, patient underwent lumbar spine MRI, three-dimensional (3D) CT, as well as X-ray scanning. The CT 3D construction images could present the practitioner with a direct visualization of the integral bone structure. General anesthesia was induced on the day of surgery. A prone position was taken, followed by an intraoperative CT to identify the target intervertebral space with the herniated disc. A 1.5\u0026thinsp;~\u0026thinsp;2.0 mm-long paramedian incision about 3.5 cm off the midline was made based on the center of the target intervertebral space. A tubular retractor system was docked against the angle of the spinous process and vertebral plate at the same level and ipsilateral to the herniated disc. If necessary, intraoperative CT imaging was performed a second time to validate the exact placement of the tubular retractor system. After the placement of the 14- or 18-mm diameter tubular retractor, microscope was brought in, followed by the partial hemi-laminotomy and excision of the underlying ligamentum flavum to expose the underlying impinged nerve root. Resection of the nucleus pulposus was performed if the herniated disc heavily compressed the nerve root. The impingement on nerve root was relieved satisfactorily, and deep fascia and the subcuticular layer were closed with absorbable sutures. No subcutaneous drainage tube was placed if no dural tear happened during the surgical procedure. After surgery, patient was guided to perform \u0026ldquo;straight leg raising exercises\u0026rdquo; on bed followed by out-of-bed activities with waist support 2\u0026ndash;3 days postoperatively. If no complications happened, patients would be discharged after a postoperative lumbar spine 3D-CT imaging.\u003c/p\u003e\u003cp\u003eBasic demographic, clinical data, and imaging findings of each patient was acquired through the retrieval of the HIS Medical Record System. Basic demographic data included name, age, and sex. Clinical data included disease duration, comorbidities, the level and side of the disc herniation, and comorbidities. Perioperative variables mainly included surgical duration, resection of nucleus pulposus and dural tears. In this study, surgical duration refers to the time interval from anesthesia induction to leaving the operation room. Postoperative items mainly consist of the total length of stay and length of stay after surgery. Severity of the radicular pain was assessed using Visual Analog Scale (VAS) at baseline and 1 day before discharge. All the clinical assessment were performed by our practitioners ( ). In this study, a total of 24 potential relevant clinical factors were selected. A complete listing of the above factors was presented in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e and Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. The factors \u0026ldquo;additional LDH\u0026rdquo; and \u0026ldquo;spinal stenosis\u0026rdquo; refer to lesions at levels other than the one being operated [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eComparisons of the binary factors between the two groups\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFactor No\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eBinary Factors\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNormal LOS Group\u003c/p\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;59)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eProlonged LOS Group\u003c/p\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;52)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003ep Value\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eX1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSex (male/female)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e27/32\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e27/25\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.517\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eX2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePreoperative immobility (yes/no)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e24/35\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e29/23\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.112\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eX3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSide (left/right)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e25/34\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e27/25\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.314\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eX4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePreoperative paresis (yes/no)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e27/32\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e21/31\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.568\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eX5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eHypertension (yes/no)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e17/42\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e16/36\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.822\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eX6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDiabetes mellitus (yes/no)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e10/49\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e8/44\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.823\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eX7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCoronary disease (yes/no)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e3/56\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e10/42\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cb\u003e0.035\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eX8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eHypothyroidism (yes/no)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2/57\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1/51\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.634\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eX9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eLasegue sign (yes/no)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e30/29\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e26/26\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.929\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eX10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSmoking (yes/no)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e9/50\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e7/45\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.788\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eX11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDrinking (yes/no)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e9/50\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e4/48\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.216\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eX12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSpinal stenosis (yes/no)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e48/11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e43/9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.855\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eX13\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSingle-level operation (yes/no)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e55/4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e45/7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.240\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eX14\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAdditional LDH (yes/no)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e39/20\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e39/13\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.306\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eX15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDrainage (yes/no)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2/57\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e2/50\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.898\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eX16\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eNucleotomy (yes/no)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e35/24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e21/31\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cb\u003e0.046\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eX17\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDural tears (yes/no)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2/57\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e2/50\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.898\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eX18\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eFar lateral LDH (yes/no)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e4/55\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e5/47\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.585\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eX19\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eHyperlipidemia (yes/no)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e15/44\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e7/45\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.115\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eX20\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAnticoagulation/antiplatelet agents (yes/no)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0/59\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e4/48\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cb\u003e0.030\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"5\" nameend=\"c5\" namest=\"c1\"\u003e\u003cp\u003eBoldface type indicates statistical significance\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eComparisons of the continuous factors between the two groups\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFactor No\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eContinuous Factors\u003c/p\u003e\u003cp\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD (range)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eNormal LOS Group\u003c/p\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;59)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eProlonged LOS Group\u003c/p\u003e\u003cp\u003e(n\u0026thinsp;=\u0026thinsp;52)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003ep Value\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eX21\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAge at surgery, years\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e55.1\u0026thinsp;\u0026plusmn;\u0026thinsp;12.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e61.8\u0026thinsp;\u0026plusmn;\u0026thinsp;14.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cb\u003e0.003\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eX22\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eDisease duration, months\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e35.2\u0026thinsp;\u0026plusmn;\u0026thinsp;75.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e37.7\u0026thinsp;\u0026plusmn;\u0026thinsp;76.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.854\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eX23\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eVAS scores at baseline\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e7.3\u0026thinsp;\u0026plusmn;\u0026thinsp;0.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e7.5\u0026thinsp;\u0026plusmn;\u0026thinsp;0.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.319\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eX24\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSurgical duration, minutes\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e145.5\u0026thinsp;\u0026plusmn;\u0026thinsp;52.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e176.2\u0026thinsp;\u0026plusmn;\u0026thinsp;56.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u003cb\u003e0.000\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"5\" nameend=\"c5\" namest=\"c1\"\u003e\u003cp\u003eBoldface type indicates statistical significance\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eAs indicated in the previous study, a prolonged length of stay (LOS) was defined as \u0026ge;\u0026thinsp;one additional day beyond the median hospital stay in our patient series. In this study, LOS referred to the total number of days the patients stayed in hospital. Readiness to be discharged from the hospital was determined by the surgeons ( ), based on the actual conditions of the patients including pain relief (VAS scores), and sufficient mobility.\u003c/p\u003e\u003cp\u003ePatients were divided into prolonged LOS group and normal LOS group. Twenty-four clinical factors, labeled X1-X24, were assessed for each group. The outcome was encoded as the variable Y, with Y\u0026thinsp;=\u0026thinsp;0 representing normal LOS, and Y\u0026thinsp;=\u0026thinsp;1 representing prolonged LOS. In the first step for bivariate analysis, each clinical variable was compared between these two groups. If significant difference existed for a variable, it would be carried over to the second step for further analysis; otherwise, this variable was excluded. In the second step, the surviving factors were brought into a binary logistic regression model.\u003c/p\u003e\u003cp\u003eChi-square test or Fisher\u0026rsquo;s exact test was performed to compare the binary variables, such as sex, smoking, and dural tears. The Mann-Whitney \u003cem\u003eU\u003c/em\u003e-test was used to compare continuous variables with non-normal distributions, while two-sample \u003cem\u003et\u003c/em\u003e test was performed to compare the continuous variables with normal distributions. Continuous variables are presented as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD (range). A value of \u003cem\u003eP\u003c/em\u003e ˂ 0.05 was recognized as statistically significant. Statistical analyses were performed with SPSS software (Version 23.0, IBM, Armonk, NY). All of the statistical analyses were performed by an experienced statistician ( ).\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eIn the 111 LDH patients (54 men and 57 women) included in our study, mean age at surgery was 58.3\u0026thinsp;\u0026plusmn;\u0026thinsp;13.8 (range, 18\u0026ndash;80) years, mean disease duration before surgery 36.4\u0026thinsp;\u0026plusmn;\u0026thinsp;75.6 (0.03\u0026ndash;480) months, total length of stay 11.1\u0026thinsp;\u0026plusmn;\u0026thinsp;3.8 (6.0\u0026ndash;28.0) days, and postoperative length of stay 7.5\u0026thinsp;\u0026plusmn;\u0026thinsp;2.7 (4\u0026ndash;24) days.\u003c/p\u003e\u003cp\u003eMedian LOS was 10 days, thus 52 and 59 patients were divided into prolonged and normal LOS group respectively. In the first step for bivariate analysis, 20 binary variables (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) and 4 continuous variables (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e) were compared between the two groups individually. Significant differences existed for 5 variables: coronary heart disease (X7, yes vs no), nucleotomy (X16, yes vs no), anticoagulation/antiplatelet agents (X20, yes vs no), age at surgery (X21) and duration of surgery (X24), and these variables were carried forward into the next step for multivariate analysis.\u003c/p\u003e\u003cp\u003eAs is seen in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, age at surgery was significantly different between the two groups (55.1\u0026thinsp;\u0026plusmn;\u0026thinsp;12.9 vs. 61.8\u0026thinsp;\u0026plusmn;\u0026thinsp;14.1, p\u0026thinsp;=\u0026thinsp;0.003). Other basic factors, including sex (X1), side (X3), smoking (X10), drinking (X11) and disease duration (X22), did not show significant between-group differences (p\u0026thinsp;\u0026ge;\u0026thinsp;0.05, Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). As for the preoperative items, statistical between-group differences existed in the factors \u0026ldquo;coronary heart disease\u0026rdquo; (p\u0026thinsp;=\u0026thinsp;0.035) and \u0026ldquo;anticoagulation/antiplatelet agents\u0026rdquo; (p\u0026thinsp;=\u0026thinsp;0.030). However, other preoperative items, including preoperative immobility (X2), preoperative paresis (X4), hypertension (X5), diabetes mellitus (X6), hypothyroidism (X7), Lasegue sign (X9), hyperlipidemia (X19) as well as VAS scores at baseline (X23), did not show significant difference between the groups (p\u0026thinsp;\u0026ge;\u0026thinsp;0.05). Radiological variables, such as spinal stenosis (X12) and additional LDH (X14) were also similar between the two groups.\u003c/p\u003e\u003cp\u003eWith regard to the variables related to surgery, there was significant between-group difference in the item of \u0026ldquo;nucleotomy\u0026rdquo; (p\u0026thinsp;=\u0026thinsp;0.046). Besides, surgical duration was significantly different between the two groups (145.5\u0026thinsp;\u0026plusmn;\u0026thinsp;52.9 vs. 176.2\u0026thinsp;\u0026plusmn;\u0026thinsp;56.9, p ˂ 0.001). Other surgical variables, such as single-level operation (X13), drainage (X14), and dural tears (X15) were balanced between the two cohorts. Therefore, the five significant variables (X7, X16, X20, X21, X24) found in bivariate analysis were then included in a logistic regression model for multivariate analysis.\u003c/p\u003e\u003cp\u003eIn the regression model, X7, X16, and X20 were treated as binary variables, while X21 and X24 were treated as continuous variables. As indicated in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, surgical duration (p\u0026thinsp;=\u0026thinsp;0.018, OR 1.010, 95% CI 1.002\u0026ndash;1.109) was the only risk factor of prolonged LOS for LDH patients with TMD, indicating patients with longer surgical duration were more likely to postpone discharging after surgery. Finally, the Spearmen correlation analyses indicated that there were significant positive correlations between the surgical duration and the prolonged total (Spearman\u0026rsquo;s rho\u0026thinsp;=\u0026thinsp;0.321, p\u0026thinsp;=\u0026thinsp;0.001, Fig.\u0026nbsp;1A) and postoperative LOS (Spearman\u0026rsquo;s rho\u0026thinsp;=\u0026thinsp;0.269, p\u0026thinsp;=\u0026thinsp;0.004, Fig.\u0026nbsp;1B).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eMultivariate logistic regression analysis of prolonged length of stay\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"7\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eVariables\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003ep value\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eOR\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003e95% CI\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eβ\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eWald\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eSE\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCoronary disease\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.313\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2.217\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.472\u0026ndash;10.416\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.796\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e1.107\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.789\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAnticoagulation/antiplatelet agents\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.999\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e6.055E8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.000-+\u0026infin;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e20.222\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.000\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e19976.922\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNucleotomy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.158\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.540\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.230\u0026ndash;1.269\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e-0.615\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e1.997\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.435\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAge at surgery\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.248\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.019\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.987\u0026ndash;1.053\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.019\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e1.336\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.017\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSurgical duration\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003e0.018\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.010\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.002\u0026ndash;1.109\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.010\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e5.593\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.004\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"7\" nameend=\"c7\" namest=\"c1\"\u003e\u003cp\u003eBoldface type indicates statistical significance\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eTo the best of our knowledge, this is the first study to investigate the potential factors that prolong the hospital stay for LDH patients after the first TMD. A total of 24 variables were selected and evaluated, five of which exhibited significant between-group differences in the bivariate analysis. Surgical duration remained as the only independent risk factor for prolonged LOS after logistic regression analysis. Furthermore, the Spearmen correlation analyses indicated that there were significant positive correlations between surgical duration and the prolonged total and postoperative LOS.\u003c/p\u003e\u003cp\u003eSurgical methods for LDH include traditional open midline or paraspinal approach, transforaminal endoscopic techniques, as well as TMD [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan additionalcitationids=\"CR12 CR13\" citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Conventional open surgery via midline or paraspinal approach usually performs extensive paraspinal muscles detachment, partial or total facetectomy. It thus increases the risk of tissue injury, spinal instability, and causes heavier burden on the patients [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. As for the endoscopic surgery, practitioners operate with the assistance of the endoscope, but might be limited by the high requirement of controlling the endoscope, and difficulty in stop bleeding [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. The microscope, instead of the endoscope, in combination with the tubular retractor systems, presents the practitioners with a more sufficient three-dimensional view, and thus improved the operative flexibility [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eRitter and colleagues [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e] investigated the risk factors for a prolonged LOS after conventional lumbar micro-discectomy; in that study, duration of surgery was treated as a categorical variable, and there was no significant effect in the bivariate analysis. Our study investigated risk factors for a prolonged LOS after TMD, and indicated that patients with longer surgical duration were more likely to postpone discharging. This controversy might be interpreted with the differences in the surgical techniques and data processing method. Compared with the conventional open surgery, duration of surgery is a reflection of operative difficulty and surgeon\u0026rsquo;s proficiency in a higher extent. It requires longer time and more meticulous manipulations in the operation on patients with more severe nerve root impingement and tissue adhesion. Besides, surgical duration was treated as a continuous variable directly in our study. Our results also emphasized the importance of improving the proficiency of the surgeon himself. However, our result must be interpreted with caution, and further studies are needed before a firm conclusion could be established.\u003c/p\u003e\u003cp\u003eSeveral previous studies have investigated the effects of demographic variables such as age on the LOS after lumbar micro-discectomy, and the results were not consistent. Khanaan and colleagues [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e] suggested that a higher age was correlated with longer LOS, and explained this correlation as a consequence of more preoperative comorbidities and postoperative complications. However, in the study of Ritter and colleagues [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e], age ˃ 65 years was significantly correlated with LOS, but age was an insignificant factor in the multivariate analysis. In our study, age, sex, as well as smoking, and drinking were balanced between the two groups and were not correlated with prolonged LOS.\u003c/p\u003e\u003cp\u003eAs for the comorbidities, diabetes mellitus was recognized as a significant risk factor associated with prolonged LOS after lumbar spine surgery in several previous studies [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Maloney and colleagues [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e] indicated a longer LOS in diabetic population who underwent open lumbar surgery, which is consistent with the study result by Guzman and colleagues [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. However, in our study, diabetes mellitus was not a significant risk factor even in the bivariate analysis. This might be explained by the optimal glycemic control in perioperative period at our center. Similarly, there were also no significant between-group differences in hypertension, hypothyroidism, or hyperlipidemia. Coronary disease was significant in bivariate analysis; however, multivariate regression analysis indicated that it was not an independent risk factor for prolonged LOS after TMD.\u003c/p\u003e\u003cp\u003eRegarding the preoperative medication, there were significant between-group difference in the exposure to anticoagulation and/or antiplatelet medication. In the multivariate regression analysis, this factor did not remain to be a potential risk factor for prolonged LOS. As indicated in the study of Ritter and colleagues [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e], this variable might be more of a confounding factor than an independent risk factor for LOS, because patients exposed to anticoagulation and/or antiplatelet medication were usually older than individuals who did not.\u003c/p\u003e\u003cp\u003eAs for the preoperative clinical conditions, bivariate analysis showed no significance in preoperative immobility, paresis, Lasegue sign, and spinal stenosis. A previous study identified preoperative immobility as an independent risk factor for prolonged LOS after single-level lumbar microdiscectomy [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. In our study, most patients with immobility preoperatively were capable of walking within days after TMD. Besides, in the preoperative evaluations, far lateral lumbar disc herniation (FLLDH) was regarded as a separate disc pathological category that required to be cautioned. FLLDH, including intraforaminal and extraforaminal lumbar disc herniation, is the herniation that occurs outside the lumbar spinal canal [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e], comprising 3\u0026ndash;12% of all lumbar disc herniations [\u003cspan additionalcitationids=\"CR23\" citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. The herniated disc compresses the exiting nerve root and dorsal root ganglion, resulting in extreme and refractory pain [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Clinical manifestations of FLLDH differed from medial disc herniation at the same spinal level, instead they resemble those of the medial disc herniation at one lower spinal segment. In the surgical treatment of FLLDH, TMD utilizes a muscle-space approach instead of dissecting subperiosteal muscle dissection, reducing the tissue damage, and shortening the postoperative recovery period [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. Thus, in our study, FLLDH was not a predictive factor for prolonged LOS after TMD.\u003c/p\u003e\u003cp\u003eIn the surgical procedures, resection of the nucleus pulposus was performed if the herniated disc protruded obviously and heavily compressed the nerve root. In our study, normal LOS group had a significant larger proportion of individuals undergoing nucleotomy than prolonged LOS group. However, the final regression model indicated that it was not a predictive factor for LOS. This results was consistent with the previous study of Ritter and colleagues [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Similarly, the ratio of dural tear and drainage were balanced between the groups, and they were not significant factors in our analysis.\u003c/p\u003e\u003cp\u003eAs mentioned earlier, surgical duration was positively correlated with LOS, thus several details should be mentioned to shorten the surgical time while improve the efficacy. Firstly, the herniated disc segmented being operated on should be precisely located based on preoperative radiology, anatomical landmark, and intraoperative CT. Secondly, the incision was 1.5 to 2.0 cm, avoiding to be too narrow or longer than necessary, followed by the blunt dissection using index finger and optimal placement of the tubular retractor systems. Thirdly, carefully preserve the paravertebral venous plexus and dural sac throughout the surgery. Finally, hydrogen peroxide and iodine irrigation was suggested before closing the incision.\u003c/p\u003e\u003cp\u003eOur study identified the potential risk factors for prolonged LOS after TMD, based on a relatively large sample size. The operations were finished by the same experienced senior surgeon, minimizing the confounding effects. In addition, we summarized the standardized process of TMD, and over 95% of the patients benefited from this surgical technique ultimately (data not shown). However, several limitations also need to be mentioned. Firstly, our study was limited by the inherent nature of its respective design. Besides, this study focused on the hospital stay, therefor the long-term clinical outcomes warranted to be evaluated in the further studies.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eIn conclusion, the present study indicated that surgical duration was a significant risk factor for prolonged hospital stay, and patients with longer surgical duration were more likely to postpone discharging after surgery. However, our results should be interpreted with caution. A larger and well-designed prospective trial are also recommended before the final establishment of the conclusion.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eLDH, lumbar disc herniation\u003c/p\u003e\u003cp\u003eVAS, Visual Analog Scale\u003c/p\u003e\u003cp\u003eTMD, tubular micro-discectomy\u003c/p\u003e\u003cp\u003eCMD, conventional micro-discectomy\u003c/p\u003e\u003cp\u003eLDH, length of stay\u003c/p\u003e\u003cp\u003eFLLDH, far lateral lumbar disc herniation\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eAll authors contributed to the study conception and design. X.W wrote the main manuscript text, performed the statistical analyses, and prepared figures. L.T performed the statistical analyses, and prepared tables. F.L reviewed the manuscript. All authors read and approved the final manuscript.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe data used to support the findings of this study are available from the corresponding author upon request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eThavarajasingam SG, Salih A, Arif A, Varadpande M, Sabeshan P, Ponniah HS, et al. Indications for surgery versus conservative treatment in the management of lumbar disc herniations: A systematic review. Brain Spine. 2025;5:105619.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eChen Y, Lin F, Wang K, Chen F, Wang R, Lai M, et al. Development of a predictive model for 1-year postoperative recovery in patients with lumbar disk herniation based on deep learning and machine learning. Front Neurol. 2024;15:1255780.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eOzer MI, Demirtas OK. 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Orthop Surg. 2025.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"lumbar disc herniation, tubular micro-discectomy, risk factor, length of stay","lastPublishedDoi":"10.21203/rs.3.rs-7910953/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7910953/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e\u003cp\u003eThis study was to identify potential risk factors for prolonged length of stay (LOS) in patients with lumbar disc herniation (LDH) after first minimally invasive tubular microdiscectomy (TMD). Demographic data, clinical records, and imaging studies were retrospectively analyzed in this study. The primary outcome was defined by the total number of days stayed at hospital. A prolonged LOS was defined as \u0026ge;\u0026thinsp;1 day beyond the median hospital stay in our patient cohort. Bivariate analysis and multivariate regression, as well as correlation analysis were conducted to investigate the risk factors for prolonged LOS.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003eA total of 111 patients who underwent TMD were consecutively included in our study. Statistical analysis of potential factors influencing LOS was performed for 24 variables independently, in which five variables significantly related to a prolonged LOS in bivariate analysis were carried into multivariate regression. Coronary heart disease, nucleotomy, and anticoagulation/antiplatelet agents were treated as binary variables, whereas age at surgery and surgical duration were treated as continuous variables. After logistic regression analysis, only surgical duration (p\u0026thinsp;=\u0026thinsp;0.018) was identified as an independent predictive factor for prolonged LOS. Finally, the Spearmen correlation analyses indicated that there were significant positive correlations between surgical duration and the prolonged total and postoperative LOS (p ˂ 0.005).\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e\u003cp\u003eOur study indicated that surgical duration was a significant risk factor for prolonged hospital stay. Further studies are needed before firm conclusions can be established.\u003c/p\u003e","manuscriptTitle":"Risk factors for prolonged length of stay after first minimally invasive tubular microdiscectomy in lumbar disc herniation","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-11-24 10:22:39","doi":"10.21203/rs.3.rs-7910953/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"ed4c28b6-65c6-494d-bea0-c378515c5858","owner":[],"postedDate":"November 24th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-01-26T12:41:23+00:00","versionOfRecord":[],"versionCreatedAt":"2025-11-24 10:22:39","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7910953","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7910953","identity":"rs-7910953","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}