Discectomy for Lumbar Disc Herniation in Pediatric and Adolescent Populations: A Systematic Review and Meta-Analysis

Corroborative evidence for discectomy in pediatric or adolescent patients remains scarce, with this single-arm meta-analysis investigating discectomy for lumbar disc herniation (LDH) within this population. PubMed, Embase (Elsevier), CiNAHL, Cochrane Library, Scopus, and Web of Science were searched. Eligible studies reported pediatric patients under 21 years of age with a diagnosis of LDH that was treated surgically with discectomy. This review was registered in PROSPERO (ID: CRD42023463358). Twenty-two studies met the eligibility criteria (n=1182). Visual analog scale (VAS) scores for back pain at baseline were 5.34 (95% CI: 4.48, 6.20, I2=98.9%). Postoperative VAS back pain scores after 12 months were 0.88 (95% CI: 0.57, 1.19, I2=95.6%). VAS scores for leg pain at baseline were 7.03 (95% CI: 6.63, 7.43, I2=93.5%). Postoperative VAS leg pain scores after 12 months were 1.02 (95% CI: 0.68, 1.36, I2=97.0%). Oswestry disability index (ODI) scores at baseline were 55.46 (95% CI: 43.69, 67.24, I2=99.9%). Postoperative ODI scores after 12 months were 7.82 (95% CI: 4.95, 10.69, I2=99.4%). VAS back, VAS leg and ODI scores demonstrated a minimum clinically important difference (MCID) at all postoperative points. Perioperative outcomes demonstrated operative time as 85.71 mins (95% CI: 73.96, 97.46, I2=99.4%) and hospital length of stay as 3.81 days (95% CI: 3.20, 4.41, I2=98.5%). The postoperative reoperation rate at the same level was 0.01 (95% CI: <0.00, 0.02, I2=0%). Discectomy appears safe and effective in pediatric and adolescent patients suffering from LDH. The findings here provide groundwork for future randomized control trials against conservative measures to elaborate on optimal management and elucidate long-term outcomes.


Introduction And Background
Lumbar disc herniation (LDH) is a condition characterized by the displacement of disc material through its external encasing membrane [1].Its pathological progression is predominantly linked to degenerative disease, involving factors such as compression, tension, shear, and torque stresses, which collectively contribute to this degeneration.These alterations result in the protrusion or herniation through the annulus fibrosus in the central canal, giving rise to clinical symptoms such as nerve root impingement and subsequent sensory motor deficits along the affected pathway [1].While the most affected demographic comprises of males between the ages of 30 and 50 years, disc herniation, albeit less frequently, can also manifest in the pediatric or adolescent population [2].Treatment approaches for both pediatric and adult populations often involve conservative management, utilizing physiotherapy and non-steroidal antiinflammatory drugs (NSAIDs) as primary modalities [1].However, in cases where symptoms align with refractory conservative measures or compressive spinal emergencies, surgical intervention becomes warranted [1].
In younger populations, cases requiring surgical interventions have been stated as approximately 5.5 per 100,000 persons amongst those under 25 years of age [3].Current surgical interventions consist of discectomy, in which offending material is surgically removed to alleviate symptoms [4].Laminectomy is also possible but reserved for more extensive cases [4].Between the two, discectomy demonstrates more advantageous perioperative outcomes due to its minimally disruptive nature toward the vertebral column [5].In adult cohorts, discectomy has been shown to result in decreased pain and increased functionality [6].Pain alleviation following discectomy is achieved through the removal of the offending material that causes nerve compression, in turn minimizing the source of inflammation and immune response [4].However, due to the lower prevalence, there are limited reports for outcomes of pediatric and adolescent lumbar discectomy in comparison to adult cohorts [7].This is problematic, as findings in the adult populations may not be directly translated to pediatric or adolescent populations due to growth and a continuously changing skeletal structure [8].
At present, there is a lack of corroborative evidence evaluating the safety and efficacy of discectomy in pediatric populations.Further investigation is needed to evaluate the alleviation of pain and functionality, measured through visual analog scale (VAS) and Oswestry disability index (ODI) scores, respectively.Additionally, elucidation is required regarding perioperative measures such as operative time, estimated blood loss, and hospital length of stay.To date, no other meta-analysis has been conducted on discectomy as a surgical intervention for pediatric and adolescent patients with LDH.As such, this study aims to shed some insight into the overall efficacy of surgical management for pediatric or adolescent populations when treating disc herniation with the current literature state.

Search Strategy and Data Sources
This review followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines [9].A comprehensive search was conducted in several databases from their respective inception dates up to September 15, 2023, without any language restrictions.The databases included PubMed, Embase (Elsevier), CiNAHL, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, Scopus, and Web of Science.The search strategy was designed and conducted by a medical reference librarian.Controlled vocabulary supplemented with keywords was used to search for studies describing lumbar discectomy in pediatric or adolescent LDHs.The actual strategy listing all search terms used and how they are combined is available in Supplemental Material 1.Additional references were sought through hand searches of Google Scholar (search terms: Discectomy; Lumbar; Pediatrics; Adolescents; Spine; Herniation).This review was registered prospectively with PROSPERO (CRD42023463358).

Eligibility Criteria and Quality Assessment
Eligible studies must have met all of the following inclusion criteria: 1) patients <21 years of age explicitly classified as either a pediatric and or adolescent population by study authors; 2) discectomy for LDH of the spine (microendoscopic discectomy (MED), percutaneous endoscopic lumbar discectomy (PELD), percutaneous laser disc decompression (PLDD), and tubular discectomy or open discectomy/microdiscectomy); 3) reported on the primary outcomes of VAS back and/or leg pain, ODI, modified MacNab criteria, hospital length of stay, estimated intraoperative blood loss, or operative time; 4) randomized, comparative, case-control, prospective, retrospective, observational cohort or case series in study design.Exclusion criteria were: 1) discectomy was a re-operation of previous surgery; 2) surgery involved laminectomy; 3) case reports, abstracts, conference abstracts, review articles, and letter-to-editors; 4) unpublished data, data published in abstract form only, or non-full-length articles; 5) studies with overlapping patient data.Conventionally, <18 years of age is considered as the pediatric patient.However, the literature demonstrates that growth and ossification of the spine do not end until the second decade of life [10].Additionally, the acceptance of 21 years of age and under for pediatric inclusion is in accordance with guidelines set by the American Academy of Pediatrics [11].These two components thus provided the rationale for the age bracket within this meta-analysis.
Article screening and data extraction were conducted by four independent assessors (AKV, ARP, KGA, TJC).Any disagreements were adjudicated by CAT and discussed with co-authors as necessary.The quality of each study was independently evaluated by two authors (ARP and KGA) using the Newcastle Ottawa Assessment Scale [12].The difference in the determination of quality was resolved by discussion with a third author until a consensus was reached (MA).All included studies were categorized as having one study arm for analysis.Included studies that involved multiple arms had only the arms involving pediatric patients with LDH receiving surgical discectomy extracted.For the purposes of the one-arm meta-analysis, studies that had multiple eligible study arms for extraction (e.g., open discectomy, MED, PELD, PLDD, or microdiscectomy) were all included and treated separately during analysis.

Outcomes
Pain and function were the outcome variables of interest in this meta-analysis.Additional primary outcomes were extracts of operative time in minutes, intraoperative blood loss in milliliters, and hospital length of stay in days.Patient perception of pain was evaluated using the VAS questionnaire score.A lower VAS score indicates less perceived pain, meaning more patient relief [13].The VAS score was used to evaluate back pain and leg pain separately.VAS scores were for back pain unless specifically stated for leg pain.Patient perception of functionality was evaluated using the ODI scores.A lower ODI score indicates less disability, meaning more patient functionality [13].Clinician perception of patient symptom relief was evaluated using the modified MacNab criteria [14].It is the subjective grading of the patient's perceived quality of surgical outcome using one of four categories: excellent, good, fair, or poor.No perceived pain, along with a return to the original level of activity, would be categorized as an "excellent" outcome.Occasional and localized pain, with relief of presenting symptoms, and return to modified work, would be considered a "good" outcome.Some improvement in functionality and the inability to return to daily activity is a "fair" outcome.Persistent objective symptoms of root involvement, along with the need for additional operative intervention, would be considered a "poor" outcome.Secondary outcomes of anatomical co-morbidities, presenting symptoms, spinal level of herniation, number of levels of operation, herniation classification, prior positive diagnostic tests, preceding trauma, postoperative complication rates (e.g., infection, cerebrospinal fluid (CSF) leak, neurological deficit), lumbar fusion requirement rate and reoperation rate were also extracted.

Statistical Analysis
Means of continuous variables and rates of binary variables were pooled using the generic inverse variance method of DerSimonian and Laird [15].Proportions underwent logit transformation prior to meta-analysis.The heterogeneity of effect size estimates across the studies was quantified using the Q statistic and the I2 index (P < 0.10 was considered significant) [16].A value of I2 of 0-25% indicates minimal heterogeneity, 26-50% moderate heterogeneity, and 51-100% substantial heterogeneity.The random-effects model was used.If mean and standard deviation (SD) were unavailable, the median was converted to mean using the formulas from the Cochrane Handbook for Systematic Reviews of Interventions [17].If SD was not available or extractable, the reported mean was omitted from the calculation.Authors were contacted three times to obtain any relevant additional information that was omitted in published articles.Publication bias was assessed using a funnel plot [18].Data analysis for a single-arm meta-analysis was performed using Open Meta analyst software (CEBM, Brown University, Providence, USA).Data for the pediatric lumber discectomy group from any multiple-arm studies were included in the one-arm study analyses of the current metaanalysis.

Data Extraction and Minimal Clinical Important Difference (MCID) Interpretation
The VAS and ODI scores were extracted in the following epochs: baseline (preoperation), up to 1 week, 1 month, 3 months, 6 months, and 12 months post-operation.A VAS score of 1.2 and 1.6 was considered as the minimum clinically important difference (MCID) in spine surgery patients with back pain and leg pain, respectively, as previously reported [19].An ODI score of 8.2 was considered as the MCID as previously reported [19].

Risk of Bias
Results of the quality assessment of all included studies are shown in Table 2.The studies were judged to be of good quality .The exposure and outcome were adequately ascertained, and the lengths of followup were adequate to manifest a change in the clinical outcomes.

Presenting Symptoms
Presenting symptoms have been reported in   The average baseline pain scores of VAS leg pain were 7.03.Up to one week, postoperative pain scores were 1.86.At one month postoperative pain scores were 1.64.At three months postoperative pain scores were 1.34.At six months postoperative pain scores were 1.02.At 12 months postoperative pain scores were 1.02.The values are depicted in Supplemental Material 4 and their associated funnel plots in Supplemental Material 5 [23,25,27,31,33,[35][36][37][38][39][40][41].Although visual inspection of funnel plots indicated asymmetry for all epochs, the inclusion of fewer than 10 studies at each point limited distinguishing chance from real asymmetry.MCID was achieved at all time points and is listed in Table 7.
Oswestry Disability Index (ODI) Baseline ODI and follow-up are listed in Table 6.The average baseline ODI was 55. 46.Up to one week postoperative ODI was 14.02.At one month postoperative ODI was 20.94.At three months postoperative ODI was 14.12.At six months postoperative ODI was 10.24.At 12 months postoperative ODI was 7.82.The values are depicted in Supplemental Material 6 and their associated funnel plots are in Supplemental Material 7 [21,23,[25][26][27]31,33,35,36,38,39].Although visual inspection of funnel plots indicated asymmetry for time points 3 months, 6 months, and 12 months, the inclusion of fewer than 10 studies at each point limited distinguishing chance from real asymmetry.MCID was achieved at all time points and is listed in Table 7.

Perioperative Outcomes
The perioperative outcomes are listed in

Discussion
The role of discectomy in the management of pediatric and adolescent LDH has steadily garnered emerging literature.The current study is the first meta-analysis to corroborate existing evidence to determine the safety and efficacy of discectomy in treating children with LDH.Our findings suggest that discectomy will improve pain and functionality promptly after surgery, with near resolution up to 12 months postoperatively.At all postoperative follow-up points, an MCID is achieved.Perioperative outcomes demonstrate a relatively short surgical time and corresponding hospital stay.Postoperative complications appear minimal, with low rates of reoperation at the same level.These findings, although preliminary, suggest that discectomy appears to be viable in certain pediatric and adolescent patients suffering LDH who are refractory to conservative measures.
Employment of conservative measures has demonstrated a 63% resorption rate by Wang et al. [42] in adult populations.However, pediatric LDH is less likely to resorb [43].Limited high-level evidence exists on the incidence of resorption of pediatric LDH, with a scarcity of studies reporting this outcome.Hence, indications for pediatric and adolescent surgery, through refractory conservative measures, warrant valid consideration based on unlikely recovery without intervention.Pediatric surgery is indicated at 4-6 weeks if severe pain persists [42].Conflicting data exists on the comparison of the long-term outcomes of conservative versus surgical treatment.However, it is broadly accepted that nonsurgical management is not as effective in children as in adults, with a recent review reporting that the short-to long-term effectiveness of conservative treatment for pediatric LDH without neurological deficits varied from 25% to 50% [14].A randomized control trial by Bailey et al. [44] concluded that surgical treatment was superior to conservative management for sciatica secondary to LDH, lasting for 4-12 months.A significant improvement in leg pain intensity score was reported at six months.The long-term benefits of surgical intervention remain scarce, although existing studies report similar pain and disability outcomes [4].In particular, a prospective cohort study evaluating the 10-year outcomes reported a more complete relief of leg pain and improved function and satisfaction with surgical management [45].Overall, it appears that discectomy is more effective in treating pediatric LDH [43].As such, some studies advocate for earlier surgical intervention in pediatric and adolescent LDH when compared to treating adults.It is suggested that such proposed approaches would lead to a decreased period of disability and streamline return to school and normal activities [46].
Both the patient's family and surgeon's apprehension to surgically manage LDH can arise from the perceived benefits and risks of the procedure.Although rare, both sides should be aware of the potential complications of discectomy.Such complications include but are not limited to, infection and postoperative neurological deficits with associated nerve root damage.However, the results of the current meta-analysis demonstrate considerably low complication rates, which are substantiated by a recent literature review also reporting low complication rates (1.0%-2.6%)[47].This is further complemented by low rates of recurrence and reoperation seen within the current meta-analysis results.The findings presented here, along with the achievement of MCID for pain and functionality, demonstrate support for discectomy as a safe and effective option for the management of pediatric LDH where needed.
Although the mechanism of pain relief through discectomy remains the same as in adults, careful consideration must account for the differences in pediatric and adolescent spinal anatomy.In particular, the vertebral canal and its associated discs may be smaller thus making the operation more technically challenging.Recent literature lacks studies that have examined the occurrence of disc disease in the pediatric population while considering the influence of skeletal maturity and hormonal changes on the developing spine [48].As children grow older, substantial changes occur in the composition and shape of their joints, as well as in the consistency of the intervertebral disc.These changes play a crucial role in the response of the spine to injury and in the effectiveness of both conservative and surgical treatments [48].
Spinal surgery at a young age sparks significant concerns regarding the future prognosis of these patients over the span of several decades.However, at present, the long-term effects of discectomy into adulthood for pediatric LDH surgeries have not been extensively studied, and as such, further investigation is required.A retrospective cohort study analyzing the long-term outcomes of discectomy in pediatric LDH, before the advent of microdiscectomy and minimally invasive discectomy, revealed that at a 20-year follow-up from the initial operation, approximately 25% of patients underwent another discectomy, with an additional 5% undergoing arthrodesis [49].A similar study, reporting the long-term outcomes of discectomy for pediatric LDH, concluded that surgical management does not appear to lead to chronic back pain, or negatively impact overall health, based on a mean follow-up of 8.5 years [50].At present, there is lacking comparable data from studies evaluating more modern surgical techniques.It is crucial to note that in the long-term, it remains unknown whether adolescents are at an increased risk of future spinal surgery by choosing surgical intervention over conservative management [47].Limited by the availability of reported long-term outcomes, our study was only able to report outcomes up to 12 months post-discectomy.

Limitations
As with all meta-analyses, limitations are present within the current study.Foremost is the high heterogeneity in outcomes, suggesting a cautionary approach to the interpretation of results.The heterogeneity can likely be attributed to the relatively small sample size and diversity in both surgical methodology and the pediatric and adolescent population across the included studies, as well as the difference in follow-up periods.This potentially limits the generalization of these results to a broader population and prohibits investigation into long-term outcomes.Thus, long-term multicenter studies, with wide-encompassing patient demographics, healthcare settings, and clinical practices would offer a more comprehensive understanding of pediatric discectomy.Second, the lack of randomized control trials within the literature prevented any form of two-arm analysis from further validating the results of the current study.Coupled with the predominantly retrospective design of the included studies, inherent challenges exist within the current meta-analysis in mitigating patient-selection bias.However, the current state of literature predominates with retrospective case series, cohort studies, and prospective observational studies rather than randomized controlled trials; hence, the nature of the overall quality of evidence found within this meta-analysis.
Third, a lack of reporting on failed preoperative conservative measures prohibited any insight into the management employed prior to the requirement for surgery.This may include epidural steroids or selective nerve root injections which would be considered non-operative modalities.Fourth, a lack of reporting regarding postoperative rehabilitative measures precluded further discussion on the influence this may have had on outcomes.Fifth, for ethical reasons, patients could not be randomized to further supplemental treatments such as analgesics or undocumented therapies, and a lack of adequate reporting prevented controlling for their effects.Sixth, not all studies controlled for surgeon experience, which may have influenced outcomes.Finally, the MCID used within the current study was based on literature calculated in adults due to lacking reports on children.Thus the cut-offs may not have the same application in pediatric populations and should be acknowledged.

Conclusions
The current work is the first meta-analysis to examine the safety and efficacy of discectomy for pediatric and adolescent patients with LDH.These findings suggest discectomy may improve patient perception of pain and functionality as measured by VAS and ODI scores, as well as the McNab criteria.The resolution of symptoms appears to manifest within the first week after surgery, with an almost sequential remission up to 12 months postoperatively.Both pain and functionality are seen to achieve MCID at all time points postoperatively.Postoperative complications appear minimal with a low reoperation rate.Therefore, in pediatric and adolescent patients who are refractory to conservative treatment for LDH, discectomy appears plausible as a therapeutic intervention.Further randomized studies against conservative management are required with higher sample sizes, standardized discectomy protocols, and longer follow-up times to elucidate the findings of this study.

Appendices
Supplemental material 1: actual search strategies

FIGURE 1 :
FIGURE 1: Preferred reporting items for systematic reviews and metaanalyses (PRISMA) flow diagram

Good quality: 3
or 4 stars (*) in the selection domain AND 1 or 2 stars in the comparability domain AND 2 or 3 stars in the outcome domain; fair quality: 2 stars in the selection domain AND 1 or 2 stars in the comparability domain AND 2 or 3 stars in the outcome/exposure domain; poor quality: 0 or 1 star in selection domain OR 0 stars in comparability domain OR 0 or 1 stars in outcome/exposure domain N/A: No association

FIGURE 2 :
FIGURE 2: Visual analog scale (VAS) back or unspecified pain A) baseline; B) up to 1 week post-operation; C) 1 month post-operation; D) 3 months post-operation; E) 6 months post-operation; F) 12 months post-operation

TABLE 1 : Clinical characteristics of studies
a and b denote the same study that was extracted as separate groups for the purpose of meta-analysis, hence the description of 27 studies within this table.Overall, 22 unique separate studies were included in this meta-analysis.FIED: full endoscopic interlaminar discectomy; MED: micro-endoscopic discectomy; NR: not reported; PELD: percutaneous endoscopic lumbar discectomy; PIED: percutaneous interlaminar endoscopic discectomy; PTED: percutaneous transforaminal endoscopic discectomy; SD: standard deviation; OLD: open laminectomy discectomy

TABLE 5 : Anatomical co-morbidities
Visual Analog Scale (VAS)VAS scores for back and leg pain, from baseline to follow-up, are listed in

Table 6 .
The average baseline pain scores of VAS back pain were 5.34.Up to one week, postoperative pain scores were 2.55.At one month postoperative pain scores were 1.87.At three months postoperative pain scores were 1.31.At six months postoperative pain scores were 1.20.At 12 months postoperative pain scores were 0.88.The values are depicted in Supplemental Material 2 and their associated funnel plots are in Supplemental Material 3[20- 25,31,33-40].Although visual inspection of funnel plots indicated asymmetry for time points 3 months, 6 months, and 12 months, the inclusion of less than 10 studies at each point limited distinguishing chance from real asymmetry.MCID was achieved at all time points and is listed in Table7.

TABLE 7 :
Minimal clinically important differenceA VAS score change of 1.2 and 1.6 was considered as the MCID in spinal surgery with back pain and leg pain, respectively.An ODI score change of 8.2 was considered as the MCID.