Impact of Lumbar Fusion Internal Fixation on Lumbar Disc Herniation in Young Patients: A Retrospective Study

Introduction

Lumbar disc herniation (LDH) is a common orthopedic disease with high rates of recurrence [1]. The primary cause of LDH is compression of nerve roots. This condition predominantly affects young males and typically presents with a prolonged course featuring various symptoms, such as lumbago, sciatica, lower-limb numbness, and cauda equina syndrome [2]. These symptoms, including severe lumbar activity restrictions, significantly disrupt patients’ regular work and daily life [2]. LDH progresses as the patient’s physical condition deteriorates, causing rupture of the annulus fibrosus, herniation of the nucleus pulposus, and compression of nerve roots and the cauda equina [3,4]. Despite improvements in LDH therapy, clinical outcomes remain suboptimal [5].

The diagnosis of LDH involves a clinical examination to identify symptoms such as radicular pain and sensory deficits [6]. Imaging is crucial for confirmation, with MRI being the criterion standard due to its superior soft-tissue contrast, effectively visualizing the herniated disc and nerve compression. In some cases, CT scans may be used, particularly if MRI is contraindicated [2]. Management strategies for LDH include both conservative and surgical approaches [7]. Typically, conservative management is initiated first, encompassing rest, physical therapy, pain management medications, and, in some cases, epidural steroid injections for radiculopathy [7]. If symptoms persist or are severe, surgical interventions such as microdiscectomy, laminectomy, or lumbar fusion may be considered. Patient education is crucial, emphasizing the importance of adherence to the treatment plan, proper body mechanics, and lifestyle modifications to prevent recurrence [7]. An interprofessional team approach is often the most effective, as it allows for a tailored treatment plan that meets the unique needs and circumstances of each patient [3,4].

The progressive development of lumbar fusion and internal fixation techniques has shown promising results, particularly for patients with aggravated pain due to unsuccessful conservative treatments. The use of spinal fusion surgery is rapidly increasing worldwide. There are several well-defined indications for lumbar fusion, including the treatment of vertebral fractures, degenerative disc herniation, spondylolisthesis, and segmental instability [8,9]. Studies have shown that lumbar fusion can help LDH patients as it reduces reoperation rates and provides stability to the affected area [10,11]. Similarly, lumbar fusion and internal fixation offer several advantages, such as promoting restoration of lumbar function and positive therapeutic effects [12]. Consequently, clinical treatment of LDH is recommended to alleviate back pain and improve patient quality of life, thereby expediting recovery.

Despite the extensive research conducted, several gaps remain in the current understanding and management of LDH. Previous studies have predominantly focused on the general population, with limited research dedicated to specific demographics, such as young adults [13,14]. This age group is particularly important due to their unique occupational and lifestyle risk factors, as well as their potential for recovery and return to full functionality. Furthermore, while numerous studies have reported on the outcomes of surgical interventions, there is a notable paucity of data regarding the long-term efficacy and patient-reported outcomes associated with different surgical techniques. Additionally, the impact of conservative management on quality of life and the prevention of chronic disability has not been thoroughly explored. These gaps underscore the need for more targeted and longitudinal research to better inform clinical practice and patient expectations. Herein, we examine the long-term outcomes of lumbar fusion and internal fixation in young patients with LDH, providing insights into the efficacy of these surgical approaches and their impact on patient-reported outcomes. Additionally, we seek to evaluate the role of conservative management within this demographic, offering a comprehensive assessment of both surgical and non-surgical treatment modalities. By addressing these gaps, our research aims to contribute to the existing evidence base, thereby guiding clinical decision-making and improving patient care for young individuals affected by LDH. Therefore, this retrospective study aimed to compare the outcomes of minimally invasive keyhole discectomy with lumbar interbody fusion and internal fixation in 330 patients aged 18–35 years diagnosed with lumbar disc herniation.

Material and Methods

ETHICS STATEMENT:

This study was conducted in accordance with the ethical standards of the institutional and national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. The study protocol was approved by the Ethics Committee of the Third Hospital of Hebei Medical University (approval no: W2021-029-1). All patients agreed and signed informed consent.

STUDY DESIGN, SETTING, AND PATIENTS:

This study was a retrospective analysis of 330 patients diagnosed with LDH who had undergone lumbar spinal surgery at our hospital between January 2016 and July 2021. Based on the applied treatment methods, patients were randomly divided into a control group (264 participants) and a research group (66 participants) using a random number table method. Patients between the ages of 18 and 35 years with confirmed lower LDH (L3/5, or/and L5/S1) were enrolled in the study. LDH was diagnosed by 2 or more senior orthopedic experts based on clinical symptoms, signs, and radiological examinations – computed tomography (CT) (Shanghai United Imaging uCT 510) and magnetic resonance imaging (MRI) (GE Discovery MR750 3.0T). We collected basic demographic and clinical data from the patients, including age, sex, family history of LDH, smoking history, daily setting time, and body mass index (BMI). BMI was calculated using the standard formula based on the patient’s height and weight measurements.

INCLUSION AND EXCLUSION CRITERIA:

The study included subjects who met the following criteria: (1) Patients diagnosed with LDH (ICD-10 code: M51.202 [15]. The diagnostic criteria were as follows: (a) patients having low back pain with radiating sciatica, (b) lower lumbar paraspinous pressure with radiating pain, (c) changes in spinal posture and asymmetric limitation of motion, (d) positive straight leg raising test and strengthening test, (e) abnormal root sensation, muscle strength, and reflexes in the lower lumbar region on the affected side, (f) appearance of lumbar disc herniation or bulging on X-ray, CT, and MRI; (2) Patients having age ≤18 and ≥35; (3) No history of ineffective surgical treatment within the past 6 months; (4) No contraindications for surgery; (5) No history of spine-related diseases or previous spinal surgeries and (6) Consistent follow-up for one year postoperatively at our hospital.

The exclusion criteria for the study were: (1) Younger than 18 or older than 35 years; (2) Chronic low back pain without a definitive diagnosis of LDH; (3) History of other lumbar surgeries; (4) Incomplete medical records; (5) Diagnosed with other spinal diseases; (6) History of mental illness, cognitive impairment, or suspected cognitive impairment; (7) History of other diseases such as myocardial infarction, severe liver or kidney dysfunction, severe infections, or severe diabetes, and (8) Missing follow-up data.

SURGICAL PROCEDURES:

Patients in the control group underwent a minimally invasive procedure with a keyhole lens. The procedure included local anesthesia, patient positioning in the lateral decubitus posture, grinding off the superior articular process, working cannula insertion, C-arm fluoroscopy positioning, guide wire incision, and hole reaming. Further steps included nucleus pulposus removal, nerve adhesion release, decompression, ring fiber formation by radiofrequency, and radiofrequency hemostasis. Observations were made on nerve root movement, blood circulation, interstitial space, and dural pulsation. Following this, 2 mL sodium hyaluronate was injected to prevent adhesion, the working cannula was removed, the incision was dressed and sutured, and postoperative vital signs were monitored.

For the research group, lumbar fusion internal fixation was performed. Patients were placed under general anesthesia in a prone position. Surgical incisions were made in the area of the herniated disc. Four screws were placed, 2 each in the neighboring upper and lower vertebrae. Following imaging examination and location confirmation, spondylolisthesis, lamina, and disc removal were performed, along with an interbody fusion apparatus and autogenous bone implantation. Afterwards, the detached spondylolisthesis segments were reduced, and systematic adjustment was carried out with screws. Postoperatively, the surgical site was meticulously cleaned, a drainage tube was inserted, and conventional anti-infective therapy was administered.

OBSERVATION INDEX:

We analyzed 330 patients with LDH using a self-constructed questionnaire to determine their demographic characteristics. Functional assessments were made before surgery and 12 months after surgery using the Oswestry Disability Index (ODI) and the Japanese Orthopedic Association (JOA) Lumbar Scales. The ODI evaluates function in areas such as pain level, walking, sitting, and social activities, with scores ranging from 0 to 50, where higher scores indicate decreased function. The Cronbach’s coefficient for the modified ODI scale was 0.894. The Cronbach’s coefficients for all items were in the range of 0.813 to 0.861, which confirms that the scale has good internal consistency reliability [16]. The JOA, on the other hand, assesses subjective symptoms, clinical symptoms, daily activity limitations, and bladder function with scores ranging from 0 to 29. Lower scores represent greater dysfunction. The inter-observer ICC value was 0.934 5, respectively, and the consistency of each individual item within the scoring system was high, with a maximum Kappa value of 0.751 and a minimum of 0.379. The JOA index is simple and easy to operate and has a high degree of validity and reliability [17], so it can be used in the clinical evaluation of the therapeutic efficacy of spinal cord cervical spondylosis.

Additionally, the pre-and post-surgical vertebral space heights of adjacent fixed segments were measured by trained medical personnel in both groups. Similarly, the degree of vertebral spondylolisthesis (grades I, II, and III) was evaluated before and 12 months after surgery in both groups.

SAMPLE SIZE CALCULATION:

The sample size was determined using a power analysis [18] with the aim of detecting a statistically significant difference in outcomes measured by the Oswestry Disability Index (ODI) and the Japanese Orthopedic Association (JOA) Lumbar Scales between a control group and a research group. We based our calculations on a medium effect size (d=0.5), a significance level (α) of 0.05 for a two-tailed test, and a power (1−β) of 80%. Assuming the standard deviation of the outcome measures as 10 and the expected difference in means between the groups as 5 points, the analysis suggested a minimum required sample size of approximately 63 participants per group. To accommodate potential dropouts and ensure robust statistical power, we included a minimum of 66 participants in each group.

STATISTICAL ANALYSIS:

Data were analyzed using SPSS 25.0 software. Continuous variables, such as the patient’s age and body mass index, were presented as mean and standard deviation. Categorical variables, including demographic and clinical characteristics, were reported as frequencies and percentages. The t test was used for comparing normally distributed continuous variables between groups to determine if the differences in means were statistically significant. For categorical variables and non-normally distributed continuous variables, the study utilized the chi-square test to examine associations between categorical data, the Fisher’s exact test for more precise measurements in smaller samples, and the Mann-Whitney U test for comparing non-normally distributed continuous variables between 2 independent groups. The significance level was set at P<0.05, indicating that results with a P value below this threshold were considered statistically significant.

Results

CHARACTERISTICS OF PATIENTS IN THE 2 GROUPS:

Table 1 displays the relevant patient data for each group in our study with respect to LDH. The control group comprised 185 males and 79 females, aged 18–35, with an average age of 26.50±6.80 years. The average BMI was 23.48±1.73, and the disease duration ranged from 2 to 24 months, with an average of 13.00±8.80 months. The research group included 38 males and 28 females, aged 18–30 years, with a mean age of 24.00±4.80 years. The average BMI was 23.26±1.82, and the disease duration ranged from 1 to 21 months, with an average of 11.00±8.00 months. There was no significant difference in these parameters between the 2 groups (P>0.05). The outcomes of other relevant data, including smoking, family history, and sedentary hours per day were also comparable (P>0.05).

GENERAL INFORMATION OF LDH PATIENTS:

The analysis included 330 patients diagnosed with LDH, of whom 67.57% were male (Table 2). Most were aged 26–35 (55.75%), with a significant proportion employed in heavy manual labor or leading a sedentary lifestyle. The body mass index was 25.0 in 58.48% of the patients, and 57.87% had no history of lumbar vertebral disc trauma. The predominant clinical symptom was lumbar pain (62.72%), followed by lower-limb pain. Physical signs most often presented were paravertebral tenderness and a positive straight leg raise test. The main location of LDH was L4–L5 (63.63%), and most CT scans displayed foraminal changes.

ODI AND JOA SCORES COMPARISON:

In the comparative analysis of the Oswestry Disability Index (ODI) and Japanese Orthopaedic Association (JOA) scores between the control and research groups, significant differences were observed after surgery (Table 3). The control group, comprising 264 patients, had a mean ODI score of 35.67 (95% CI: 34.34–36.99) pre-surgically, which reduced to 26.57 (95% CI: 25.24–27.90) after 12 months, indicating a substantial improvement. Conversely, the research group, with 66 patients, showed a more pronounced decrease in ODI scores, from 35.18 (95% CI: 33.46–36.90) pre-surgically to 12.36 (95% CI: 11.05–13.67) after surgery. The JOA scores also reflected a similar trend, with the control group’s mean score increasing from 7.69 (95% CI: 7.06–8.32) to 18.82 (95% CI: 18.19–19.45), and the research group’s score escalating from 8.02 (95% CI: 7.20–8.84) to 29.65 (95% CI: 28.33–30.97). The minimal clinically important difference (MCID) for ODI and JOA scores was set at 0.4 and 9.7, respectively, for the control group, and 0.2 and 2.8 for the research group, suggesting that the observed changes were well beyond the threshold of clinical significance. Statistical analysis revealed a non-significant t-value of 0.660 for the ODI pre-surgery comparison (P=0.509), but highly significant t-values of 30.000 for ODI post-surgery (P=0.001), 1.843 for JOA pre-surgery (P=0.066), and 25.620 for JOA post-surgery (P=0.001), showing the effectiveness of the surgical intervention in the research group.

COMPARISONS OF ADJACENT SEGMENT HEIGHT:

In the comparative study of vertebral space heights in adjacent fixed and line segments between the control and research groups, significant post-surgical changes were observed (Table 4). The control group, with 264 cases, exhibited a slight reduction in the fixed segment from a pre-surgical mean of 0.90 (95% CI: 0.82–0.98) to 0.74 (95% CI: 0.69–0.79) after 12 months, while the adjacent line segments showed a decrease from 1.26 (95% CI: 1.11–1.41) to 0.97 (95% CI: 0.91–1.03). In contrast, the research group of 66 cases demonstrated a more substantial decrease in the fixed segment, from 0.92 (95% CI: 0.83–1.01) pre-surgically to 0.50 (95% CI: 0.47–0.53) after surgery, and a notable reduction in the adjacent line segments from 1.35 (95% CI: 1.16–1.54) to 0.64 (95% CI: 0.59–0.69). The statistical analysis revealed non-significant t-values for the control group’s pre-surgical fixed segment (t=1.083, P=0.279), but highly significant reductions for the research group in both the fixed segment (t=27.210, P=0.001) and adjacent line segments (t=21.180, P=0.001) after 12 months, indicating the effectiveness of the surgical intervention in the research group. The t-values for the adjacent line segments also showed significant differences between the 2 groups (t=2.349, P=0.019), suggesting a more pronounced effect of the surgical procedure on the adjacent segments in the research group.

SPONDYLOLISTHESIS COMPARISONS:

As depicted in Table 5, there was no significant difference in the degree of preoperative spondylolisthesis between the 2 groups (P>0.05). However, 12 months after surgery, while there was no significant difference in the degree of grade 1 and 2 spondylolisthesis (P>0.05), a significant difference was observed in grade III spondylolisthesis between the control and research groups (P<0.05).

COMPARISON OF ADVERSE REACTIONS:

The research group had a significantly higher postoperative fusion rate and a lower frequency of adverse reactions than the control group (P<0.05) (Table 6). Adverse reactions included adhesion of nerve roots, poor wound healing, nerve root damage, and rupture of the dura mater. There were 30 cases of adverse reactions in the control group and only 5 cases in the research group (11.36 vs 7.57%; P=0.049).

CLINICAL EFFICACY COMPARISONS:

Although there was no statistically significant difference in clinical efficacy between the 2 groups, the research group had a higher overall treatment efficacy and effective rate than the control group (96.96 vs 87.12%) (Table 7).

Discussion

Our study aimed to investigate the impact of lumbar fusion with internal fixation on lumbar function in young patients with LDH. The results demonstrated that patients who underwent lumbar fusion internal fixation (research group) had significantly better postoperative outcomes compared to those who underwent minimally invasive procedures (control group). Specifically, the research group had lower ODI scores and higher JOA scores, indicating improved functional status and reduced disability. Additionally, the research group had a lower intervertebral space height and a lower incidence of grade III spondylolisthesis, along with a lower rate of adverse effects and higher treatment efficacy, although the latter was not statistically significant.

LDH patients typically experience intense pain and varying degrees of lumbar functional impairment, significantly reducing their quality of life. LDH is also more difficult to treat than other disorders [19,20]. Previous clinical treatments have favored lumbar fusion internal fixation, which involves implanting autologous bone and a lumbar fusion apparatus to reduce and fix lumbar spondylolisthesis [21]. This method accelerates the recovery of lumbar function, enhances lumbar stability, reduces the risk of adverse reactions, and helps to alleviate pain caused by lumbar lesions, thus improving patients’ quality of life [22]. However, some studies have suggested that the reoperation rate of endoscopic discectomy is higher than that of lumbar fusion plus internal fixation due to the steep learning curve for surgeons and the limited operative field [23,24].

Evidence from clinical studies supports the effectiveness of lumbar fusion internal fixation in improving outcomes for LDH patients. For example, a study comparing different surgical modalities found significant improvement in terms of VAS scores for low back pain and leg pain, as well as JOA and Oswestry Disability Index (ODI) scores, favoring the endoscopic and fixation groups over simple discectomy [25]. Another study reported that the reoperation rate and complications were significantly higher in the conventional re-discectomy group compared to the TLIF with unilateral fixation group, highlighting the advantages of lumbar fusion in terms of lower recurrence and fewer complications [26].

The Oswestry Disability Index (ODI) score is a commonly used measure to evaluate the function of lumbar spine diseases, while the Japanese Orthopaedic Association (JOA) score is a standard scoring system for human dysfunction [27,28]. These scores have been employed to assess the lumbar function of patients undergoing lumbar fusion and internal fixation for LDH and can accurately represent patients’ postoperative recovery. In our study, we utilized these scores to evaluate the outcomes of patients who underwent lumbar fusion and internal fixation for LDH. We found that the study group, which received the surgical intervention, had a lower ODI score and a higher JOA score compared to the control group. This indicates that the surgical treatment was effective in reducing the disability and pain associated with LDH, and in improving ability to perform daily self-care activities. Our findings are in line with previous studies. For example, a study evaluating the short-term therapeutic efficacy of the Isobar TTL dynamic internal fixation system for lumbar degenerative disc diseases demonstrated significant improvements in ODI and JOA scores postoperatively, highlighting the effectiveness of this approach [27]. This suggests that surgical interventions, including dynamic internal fixation systems, can lead to improved functional outcomes for patients with lumbar spine conditions. Additionally, a randomized trial [28] investigated the impact of a nurse-led early rehabilitation program following minimally invasive lumbar internal fixation. The trial found that patients in the treatment group had lower ODI scores and higher JOA scores postoperatively compared to the control group, indicating better functional recovery. This highlights the potential benefits of combining surgical treatment with early rehabilitation programs to enhance recovery. Compared to these studies, our research contributes additional evidence supporting the use of lumbar fusion and internal fixation for the treatment of LDH. Our results, which show improvements in both ODI and JOA scores, further validate the effectiveness of these surgical interventions in improving patients’ postoperative function and quality of life. The findings underscore the importance of considering both pain reduction and functional improvement when evaluating the success of treatments for lumbar spine conditions.

The intervertebral height, or the longitudinal height of the intervertebral disc when supported, reflects the status and degree of intervertebral disc change, and its alteration can predict the occurrence of intervertebral disc diseases [29,30]. Some researchers have noted that internal fixation and lumbar fusion can enhance the fixed height of neighboring segments and lower the occurrence of disc disorders [31]. Our results support these findings, showing that the postoperative intervertebral space height of the fixed and neighboring segments in the study group was considerably higher than that in the control group. This indicates that lumbar fusion with internal fixation not only stabilizes the affected segment but also helps in maintaining the height of adjacent intervertebral discs, potentially reducing the risk of future disc degeneration [32].

Lumbar spondylolisthesis can be classified into 3 grades: grade I represents a mild degree of spondylolisthesis, grade II indicates a moderate degree, and grade III reflects a severe degree [33,34]. Lumbar fusion internal fixation has been found to effectively treat LDH patients by lessening the severity of spondylolisthesis and preventing its progression [35,36]. Similar to these reports, our results showed an improvement in grade I lumbar spondylolisthesis in the study group compared to grades II and III in the control group after surgery, affirming the efficacy of lumbar fusion internal fixation in treating lumbar spondylolisthesis. This indicates that lumbar fusion internal fixation not only stabilizes the affected segments but also helps in reducing the progression of spondylolisthesis and improving patient outcomes [37,38].

Our study demonstrated that the research group had a significantly higher postoperative fusion rate and a lower frequency of adverse reactions compared to the control group. These findings align with previous studies that have reported better outcomes for advanced fusion techniques. For instance, Kang et al [39] found circumferential fusion techniques had superior fusion rates and lower adverse event rates, suggesting a balance between efficacy and safety. Similarly, Patel et al [40] emphasized the importance of standardized postoperative analgesia protocols in reducing opioid-related adverse events and improving pain management outcomes. In terms of clinical efficacy, while there was no statistically significant difference between the 2 groups, the research group showed a higher overall treatment efficacy, consistent with Rehman et al [41], who reported better clinical outcomes with newer fusion techniques. Qin et al [42] also found that minimally invasive fusion methods led to improved functional outcomes and reduced complications. These studies underscore the efficacy and safety of advanced lumbar fusion techniques in enhancing patient outcomes and minimizing adverse reactions.

While this study provides valuable insights for clinical practice, it has several limitations. These include short follow-up durations, small sample sizes, a lack of high-quality randomized controlled trials (RCTs), and heterogeneity in patient populations. To address these issues, future research should include longer follow-up periods to assess long-term outcomes and complications, larger sample sizes to improve statistical power, and more RCTs to provide higher-level evidence. Given that this study was conducted at a single center, it is crucial to design a rigorous multicenter study to confirm these results. Additionally, evaluating the cost-effectiveness of different surgical techniques is crucial for making informed healthcare decisions.

Conclusions

In summary, lumbar fusion internal fixation significantly enhances postoperative outcomes for lumbar disc herniation in young patients, as evidenced by improved Oswestry Disability Index and the Japanese Orthopedic Association scores, higher intervertebral height, and a reduction in spondylolisthesis severity. This surgical approach not only stabilizes affected segments but also mitigates the progression of lumbar spondylolisthesis and reduces the risk of future disc degeneration. Additionally, the procedure leads to higher postoperative fusion rates and fewer adverse reactions, affirming the efficacy and safety of advanced lumbar fusion techniques in improving patient quality of life.