Efficacy evaluation of the cervical posterior “keyhole technique” in the treatment of cervical radiculopathy: A retrospective case series

Ruohui Tang; Jin Yin; Zhixiang Zhang; Zichao Chen; Yixin Li; Zhaowen Zhou

doi:10.1371/journal.pone.0359633

. 2026 Oct 27;21(10):e0359633. doi: 10.1371/journal.pone.0359633

Efficacy evaluation of the cervical posterior “keyhole technique” in the treatment of cervical radiculopathy: A retrospective case series

Ruohui Tang ¹, Jin Yin ¹, Zhixiang Zhang ¹, Zichao Chen ¹, Yixin Li ¹, Zhaowen Zhou ^1,^*

Editor: Dean Chou²

PMCID: PMC13712521 PMID: 42945189

Abstract

Study design

Retrospective clinical study.

Objective

To evaluate the efficacy of endoscopic posterior keyhole decompression for cervical radiculopathy and to investigate the correlation between decompression parameters and clinical outcomes.

Summary of background data

Cervical radiculopathy traditionally requires anterior cervical discectomy and fusion (ACDF) or open posterior decompression. Although ACDF is the gold standard, it is associated with adjacent segment degeneration and implant-related complications. Minimally invasive posterior keyhole techniques aim to reduce surgical trauma; however, the optimal extent of decompression required for symptomatic relief remains unclear.

Methods

Forty patients with single-level cervical radiculopathy treated via unilateral endoscopic posterior keyhole decompression (strictly limited to targeted foraminotomy and partial medial facetectomy) (2021–2024) were reviewed. Clinical outcomes were assessed using the Visual Analog Scale (VAS) and Neck Disability Index (NDI) preoperatively, at discharge, and at 6 months postoperatively. Decompression parameters were quantified via postoperative CT. Statistical analysis included paired t-tests and Pearson correlation.

Results

All 40 procedures were successful. Specifically, 25 patients underwent isolated foraminotomy, and 15 received foraminotomy combined with discectomy, without any progression to interlaminar decompression or laminectomy. The mean operative time was 70.4 ± 24.7 minutes, and the mean blood loss was 11.7 ± 10.9 ml. Significant improvements in clinical scores were observed at all postoperative time points (P < 0.05). Statistical analysis revealed that neither the concurrent execution of a discectomy nor the diameter of the bony decompression window was significantly associated with the degree of postoperative symptom improvement.

Conclusions

This study demonstrates that endoscopic posterior keyhole decompression is a safe and feasible technique that provides favorable short-term clinical outcomes with minimal surgical trauma. The findings strongly suggest that clinical efficacy depends on targeted neural decompression (determined by intraoperative nerve root mobility) rather than the maximal removal of disc tissue or extensive laminoforaminotomy.

Introduction

Cervical spondylosis is a widespread degenerative disorder whose clinical manifestations vary by age, gender, and occupation, with a notable trend toward increasing prevalence in younger demographics. It is crucial to distinctively classify CSR from degenerative cervical myelopathy (DCM). As clarified by the AO Spine Knowledge Forum [1], DCM primarily involves spinal cord compression and upper motor neuron signs, whereas CSR is strictly characterized by isolated nerve root compression leading to dermatomal and myotomal deficits. While conservative management remains the primary therapeutic approach for CSR, a subset of patients requires surgical intervention due to refractory symptoms [2]. Historically, anterior cervical discectomy and fusion (ACDF) has been considered the “gold standard.” Over the past two decades, the surgical management of CSR has evolved significantly. While ACDF remains common, an increasing number of studies have demonstrated the efficacy of full-endoscopic posterior cervical foraminotomy. For instance, Ruetten S et al. [3] and Yang JS et al. [4] conducted comparative studies indicating that endoscopic approaches yield clinical outcomes comparable to conventional anterior surgery, but with the distinct advantages of reduced tissue trauma and preservation of segmental mobility. Similarly, Kim et al. [5] showed that posterior foraminotomy offers excellent long-term clinical and biomechanical results for posterolateral soft disc herniations. These foundational studies have fueled the ongoing debate between anterior and posterior approaches, highlighting the need for further refinement of endoscopic indications. However, recent literature highlights the inherent risks of the anterior approach, including dysphagia, adjacent segment degeneration (ASD), and the loss of segmental motion [6]. Consequently, posterior minimally invasive spine surgery (MISS) has gained significant traction. Specifically, the endoscopic posterior cervical foraminotomy (the “keyhole” technique) has emerged as a highly effective alternative, aiming to directly decompress the nerve root while preserving the intervertebral disc and motion segment [7–9].

Despite the technical maturation of the posterior endoscopic approach, a critical clinical debate remains unresolved: whether concurrent removal of the intervertebral disc (discectomy) is strictly necessary during the foraminotomy, or if bony decompression alone is sufficient for optimal symptomatic relief. To further evaluate the clinical efficacy of this approach and to provide preliminary insights into the necessity of adjunctive discectomy, we conducted a retrospective analysis of 40 patients with single-level cervical radiculopathy treated via the posterior keyhole technique at the First People’s Hospital of Kunming between March 2021 and December 2024.

Materials and methods

General data and patient selection

This study was approved by the Institutional Review Board (Ethics Committee) of Kunming First People’s Hospital (Approval No. 2025-018-01). All procedures were performed in accordance with the Declaration of Helsinki. The requirement for informed consent was waived by the Ethics Committee of Kunming First People’s Hospital due to the retrospective nature of the study. Because this is a retrospective observational study evaluating past medical records, the requirement for direct patient consent was waived by the Ethics Committee. All patient data were anonymized before analysis to protect patient privacy. The study included patients who underwent surgery between March 2021 and December 2024. For research purposes, the medical records and clinical data were accessed between 01/06/2025 and 31/08/2025.

The inclusion criteria were: (1) unilateral single-level CSR diagnosed clinically and radiographically; (2) failure of strict conservative treatment for at least 6 weeks; and (3) presence of corresponding soft disc herniation or foraminal bony stenosis. The exclusion criteria were: (1) clinical or radiographic evidence of cervical myelopathy (DCM); (2) severe cervical instability or kyphotic deformity; (3) multi-level symptomatic radiculopathy; (4) previous cervical spine surgery at the same level; and (5) active spinal infection or malignancy. The cohort consisted of 22 males and 18 females, with an average age of 56.8 ± 8.54 years. The treated levels included C4/5 (n = 1), C5/6 (n = 19), C6/7 (n = 19), and C7/T1 (n = 1). The distribution of surgical segments is illustrated in Fig 1.

Diagnostic criteria

The diagnosis of cervical spondylotic radiculopathy (CSR) was based on the “Expert Consensus on the Standardization of Diagnosis and Treatment of Cervical Spondylotic Radiculopathy (2015),” requiring the fulfillment of the following criteria: 1) Clinical Manifestations: Presence of typical radicular symptoms and neurological signs (e.g., sensory or motor deficits) that correspond precisely to the dermatomal or myotomal distribution of the affected cervical nerve roots. 2) Provocative Maneuvers: Positive results in the brachial plexus tension test (Eaton’s sign) or the neck compression test (Spurling’s sign). 3) Imaging Confirmation: Radiographic and CT evidence of cervical degeneration (e.g., osteophyte formation, foraminal stenosis) and MRI confirmation of nerve root compression at the symptomatic level. 4) Differential Diagnosis: Exclusion of other pathologies presenting with upper limb pain, such as rotator cuff disorders, thoracic outlet syndrome, lateral epicondylitis (tennis elbow), and organic spinal lesions (e.g., primary or metastatic tumors, spinal tuberculosis).

Surgical method

All procedures were performed using the TH8700-031L endoscopic system. After induction of general anesthesia, patients were placed in the prone position with the head stabilized in a neutral or slightly flexed position using a headrest. The upper limbs were positioned at the sides and, when necessary, tractioned caudally and secured with adhesive tape to enhance fluoroscopic visualization of the lower cervical segments. The target level and corresponding skin projection were localized under C-arm fluoroscopy. A 1.0-cm longitudinal skin incision was made at the identified entry point. An 8-mm outer diameter working channel was introduced stepwise using a series of blunt dilators. The endoscope was then inserted and coupled with a continuous irrigation system, a light source, and a suction device. Under endoscopic visualization, soft tissues were dissected using a radiofrequency (RF) electrode and endoscopic graspers to expose the “V-point”—the anatomical junction formed by the inferior margin of the superior lamina, the superior margin of the inferior lamina, and the medial aspect of the facet joint. A high-speed diamond burr was utilized to perform a laminotomy and partial medial facetectomy. This involved resecting the inferolateral margin of the cranial lamina, the superolateral margin of the caudal lamina, and the medial portion of the facet joint. The ligamentum flavum was then removed to fully decompress the lateral thecal sac and the exiting nerve root.

It should be clearly specified that the scope of decompression in our technique was aimed exclusively at foraminotomy and partial medial facetectomy; no interlaminar decompression or laminectomy was performed. Meticulous hemostasis was maintained using the RF electrode. The decision to perform a concurrent discectomy was determined by a combination of preoperative MRI findings and intraoperative exploration. Specifically, if intraoperative assessment revealed that the posterior annulus fibrosus remained intact and the nerve root tension decreased significantly after precise microscopic bony and ligamentous decompression, the disc was not excised. We maintain that precise posterior decompression is the critical factor in relieving nerve root compression symptoms. After confirming the adequate decompression and mobility of the nerve root, the endoscope was withdrawn, and the incision was closed with interrupted sutures. In cases with concomitant disc herniation that met the aforementioned criteria, a targeted fragmentectomy was performed, followed by thermal annuloplasty using the RF electrode (Fig 2).

Fig 2 — B. Main intraoperative steps of the endoscopic procedure. **B1:** After confirming the surgical level via fluoroscopy, the working channel and endoscope are sequentially inserted. Under endoscopic visualization, the soft tissues on the surface of the lamina and lateral mass joint are cleared. The “V-point” (indicated by a star) is exposed laterally through the interlaminar space, and a high-speed burr is used to drill the bone at the V-point. **B2:** A Kerrison rongeur is used to bite off the residual thin layer of bone, further exposing the V-point. **B3:** The lateral edge of the ligamentum flavum and the dorsal membranous structure of the nerve root are exposed. After identifying the nerve root, a partial resection of the ligamentum flavum is performed to further decompress the dorsal aspect of the nerve root canal. **B4:** A nerve hook is used to gently retract the nerve root. The axilla and shoulder regions of the nerve root are carefully explored, and the herniated disc material (nucleus pulposus) is removed to achieve complete release and mobilization of the nerve root.

Perioperative management and outcome measures

To minimize perioperative capillary hemorrhage and local inflammatory response, 0.5 g of tranexamic acid was administered intravenously 30 minutes prior to the incision, followed by an additional 0.5 g dose postoperatively. Postoperative analgesia was standardized using nonsteroidal anti-inflammatory drugs (NSAIDs). Additionally, depending on the severity of residual symptoms, adjunct therapies including osmotic diuretics, low-dose glucocorticoids, or neurotrophic agents were administered.

Additionally, local steroid injections were not utilized during the procedures. Systemic steroids were not administered routinely. Only in cases where patients experienced transient limb numbness within 24 hours postoperatively (n = 3), an intravenous dose of 60 mg methylprednisolone was administered to alleviate nerve root edema. For patients who underwent adjunctive discectomy, a soft cervical collar was recommended during physical activities for 6–8 weeks to ensure localized stability during the early healing phase. Regular outpatient follow-ups were conducted monthly to evaluate symptomatic recovery and monitor cervical stability via dynamic radiographic studies. Clinical outcomes were quantified using the Visual Analog Scale (VAS) for pain, the Japanese Orthopedic Association (JOA) score for neurological function, and the Neck Disability Index (NDI) for functional disability. The adequacy of neural decompression was assessed by comparing preoperative MRI with postoperative CT scans, specifically focusing on the dimensions of the newly created bony window and the relief of foraminal stenosis. All radiological measurements were performed independently by two spine surgeons who were not involved in the surgical procedures and were strictly blinded to the patients’ clinical outcomes. Any discrepancies were resolved by consensus.

Statistical methods

Statistical analysis was conducted using SPSS version 22.0. Continuous variables, including clinical scores and surgical metrics, were expressed as mean ± standard deviation (SD). The normality of the data distribution was confirmed using the Shapiro-Wilk test. To compare clinical outcomes (VAS, JOA, and NDI scores) between preoperative and postoperative time points (at discharge and 6-month follow-up), the paired t-test was employed. Pearson correlation analysis was utilized to assess the relationship between the degree of improvement in clinical scores and the transverse diameter of the decompression window. A P-value of less than 0.05 was considered statistically significant.

Results

Perioperative data

All 40 procedures were completed successfully without conversion to open surgery. The mean operative time was 70.4 ± 24.7 minutes, with a mean intraoperative blood loss of 11.7 ± 10.9 mL. The average hospital stay was 6.2 ± 3.2 days, and the mean hospitalization cost was 10,706.2 ± 4,205.8 CNY. During the follow-up period, two patients experienced a recurrence of symptoms. Both patients subsequently underwent Anterior Cervical Discectomy and Fusion (ACDF) surgery and achieved satisfactory relief. Clinical outcomes, as measured by VAS, JOA, and NDI scores, demonstrated significant improvement at both discharge and the 6-month postoperative follow-up compared to preoperative baselines (all P < 0.05, Table 1). Specifically, the mean VAS score decreased from 3.9 ± 1.2 preoperatively to 2.2 ± 1.0 at discharge and 1.1 ± 0.8 at 6 months. The mean JOA score improved from 12.4 ± 1.6 preoperatively to 13.9 ± 1.6 and 15.6 ± 1.3 at the respective follow-up points. Furthermore, the mean NDI score significantly declined from 16.1 ± 5.3 preoperatively to 9.6 ± 3.9 at discharge and 4.9 ± 3.2 at the 6-month follow-up.

Table 1. VAS, JOA, and NDI scores at the preoperative, before-discharge, and 6-month postoperative assessments. Values are mean ± SD. The P values refer to paired comparisons between the preoperative score and the score at the corresponding later time point.

Time Point	VAS Score	JOA Score	NDI Score
Preoperative	3.9 ± 1.22	12.4 ± 1.57	16.1 ± 5.28
Before Discharge	2.2 ± 1.00	13.9 ± 1.61	9.6 ± 3.89
6 Months Postoperative	1.1 ± 0.76	15.6 ± 1.29	4.9 ± 3.16
Preoperative/Before Discharge P-value	1.1624 × 10⁻⁹	3.7307 × 10 ⁻¹³	2.2759 × 10⁻¹⁷
Preoperative/6 Months Postoperative P-value	1.3401 × 10⁻¹⁵	1.2035 × 10⁻¹⁷	5.2116 × 10 ⁻¹⁹

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Imaging findings

A subgroup of 20 patients (14 males, 6 females) underwent postoperative CT evaluation to assess the anatomical extent of decompression (Fig 3). The remaining 20 patients did not undergo postoperative CT or MRI scans. This was primarily due to rapid postoperative discharge (often on postoperative day 1 or 2) prior to scheduling the scan. Furthermore, strict health insurance payment policies and the additional financial burden led to direct patient refusal to undergo routine postoperative imaging, especially given their significant clinical symptomatic improvement. The surgical levels in this subgroup included C4/5 (n = 1), C5/6 (n = 9), and C6/7 (n = 10) (Table 2). Based on postoperative CT analysis, the mean maximum transverse diameter of the decompression window was 8.7 ± 0.93 mm. The mean lateral offset of the decompression center from the midline was 13.5 ± 1.13 mm, and the radiographic depth of the decompression area was 62.3 ± 15.50 mm (Table 3). Decompression depth was measured on axial CT slices. Notably, as the surgical trajectory was not perpendicular to the coronal plane, a systematic discrepancy exists between the measured radiographic depth and the actual intraoperative insertion depth. Pearson correlation analysis was performed to evaluate the relationship between the transverse diameter of the decompression window and clinical recovery (improvements in VAS, JOA, and NDI). No statistically significant correlations were identified (all P > 0.05), suggesting that clinical symptomatic relief was not significantly associated with the width of the decompression window within the range observed (Fig 4).

Table 2. Segment distribution and segment-specific measurements of the maximum decompression transverse diameter, puncture depth, and center-point offset in the cervical spine. The number of cases is shown for each segment.

Segment	Number of Cases	Maximum Decompression Transverse Diameter (mm)	Puncture Depth (mm)	Offset of Center Point (mm)
C4/5	1	7.3	45.4	13.09
C5/6	9	8.8 ± 0.55	57.3 ± 13.3	12.9 ± 1.55
C6/7	10	9.0 ± 0.98	68.7 ± 13.8	13.9 ± 0.92

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Table 3. Correlations between the decompression transverse diameter and VAS, JOA, and NDI scores. The shared heading above the right-hand columns denotes the decompression transverse diameter (mm).

	Decompression Transverse Diameter/mm
Variable	Correlation Coefficient r	P-value
VAS Score	−0.229	0.332
JOA Score	0.213	0.368
NDI Score	0.080	0.736

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Fig 4 — Scatter plots showing the relationship between improvements in VAS score, JOA score, NDI score, and the decompression transverse diameter.

Quantitative evaluation

Based on preoperative pathology and surgical planning, the cohort was divided into two subgroups: 25 patients underwent isolated foraminotomy, and 15 patients underwent foraminotomy combined with discectomy (removal of the herniated nucleus pulposus). None of the patients in our cohort received interlaminar decompression or laminectomy. Intergroup analysis revealed no statistically significant differences between these two subgroups regarding operative time, intraoperative blood loss, or hospitalization costs (all P > 0.05). Furthermore, there were no significant differences in preoperative JOA scores, postoperative JOA scores, or the JOA recovery rate between the groups (Table 4). (JOA recovery rate = [postoperative score – preoperative score] / [17 – preoperative score] × 100%). However, given the limited sample size, these findings should be interpreted with caution and cannot definitively establish the clinical equivalence of the two strategies.

Table 4. Comparison of perioperative outcomes and JOA scores between decompression alone and decompression combined with nucleus pulposus removal. Values are mean ± SD. F and P values report between-group comparisons for each variable.

Group	Number of Cases	Surgical Time (min)	Blood Loss (ml)	Hospitalization Cost (CNY)	Preoperative JOA Score	Postoperative JOA Score at 6 Months	Improvement Rate
Decompression Only	25	69.1 ± 23.1	13.4 ± 12.7	10792.2 ± 5076.7	12.7 ± 1.40	15.6 ± 1.44	0.75 ± 0.16
Decompression + Nucleus Pulposus Removal	15	72.3 ± 28.4	9.1 ± 7.5	10577 ± 2734.8	11.9 ± 1.73	15.7 ± 1.05	0.68 ± 0.32
F-value	/	0.15	1.41	0.02	2.56	0.32	0.85
P-value	/	0.69	0.24	0.88	0.11	0.57	0.36

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Discussion

In this study, the significant improvements in VAS, JOA, and NDI scores observed at discharge and the 6-month follow-up underscore the feasibility and safety of the posterior “keyhole” technique for treating unilateral CSR. Traditionally, ACDF has been the gold standard for single-level cervical radiculopathy. Since Ruetten et al. [10] introduced the posterior full-endoscopic interforaminal technique in 2007, it has been discussed in the literature as a minimally invasive alternative. Meta-analyses by Sahai et al. [11] and Fang et al. [12] have reported that the posterior approach yields similar improvements in clinical scores compared to ACDF. While the rapid recovery and high patient satisfaction observed in our cohort align with these general background findings, it is important to emphasize that because our study lacks a comparison group, we cannot draw any conclusions regarding whether this technique is equivalent or superior to ACDF. It is worth noting that the average length of hospital stay in our cohort might appear longer than typically reported in outpatient settings. This duration was not driven by surgical complications or delayed postoperative recovery; rather, it reflects local hospital protocols where routine preoperative examinations and scheduling delays (1-to-3 day waiting period for inpatient MRI appointments) contribute to the overall hospitalization time.A primary focus of our study was whether the concurrent removal of the nucleus pulposus is essential during posterior decompression. Our sub-group analysis revealed no significant differences in clinical recovery or JOA improvement rates between patients who underwent isolated foraminotomy and those who received adjunctive discectomy. However, this subgroup comparison is significantly underpowered (n = 25 vs. n = 15). Therefore, the lack of statistical significance does not establish clinical equivalence between the two approaches. While our preliminary clinical observation suggests that isolated bony decompression might provide short-term symptomatic relief for certain encapsulated protrusions without the need for aggressive disc removal, this hypothesis remains speculative and requires validation in adequately powered studies.

Regarding the two cases of recurrence in our cohort, we hypothesize that posterior decompression provides limited relief for severe, progressive anterior compression. Furthermore, the progression of adjacent segment degeneration (ASD) can lead to recurrent symptoms that overlap with the initial presentation. Therefore, for patients with massive protrusions or severe ASD, preoperative counseling must emphasize these limitations to manage treatment expectations. Additionally, while we administered an intravenous dose of methylprednisolone in a small subset of patients (n = 3) who experienced transient postoperative limb numbness, systemic steroids were not used routinely. The sustained improvements observed in the overall cohort at the 6-month follow-up indicate that mechanical decompression is the primary driver of recovery.Precise anatomical localization is the cornerstone of the keyhole technique. Our CT follow-up identified the optimal decompression center at an average of 13.5 mm from the midline. The “V-point” remains the critical intraoperative landmark; however, its projection varies by segment. As noted by some scholars, the V-point moves medially relative to the dura mater in lower cervical segments, necessitating more lateral bone resection while exercising caution medially to protect the spinal cord [13].

Regarding the extent of decompression, our correlation analysis showed that clinical improvement was not significantly associated with the transverse diameter of the bone window (average 8.7–8.8 mm). While this observation aligns with the concept of “targeted decompression” (focusing on precise neural foramen enlargement rather than extensive bone removal), the current study does not have sufficient power or design strength to make definitive mechanistic claims. We cannot conclusively state that clinical efficacy depends solely on targeted neural decompression rather than wider laminoforaminotomy. To preserve vertebral stability, it is essential to retain more than 50% of the facet joint [14]. While the traditional keyhole technique is localized, more advanced approaches, such as the unilateral approach for bilateral decompression, can offer a wider decompression range when necessary [15]. Furthermore, while our study focuses on single-level pathology, the management of multilevel or bilateral pathology warrants attention. For multilevel disease, multiple targeted keyholes can be performed sequentially while preserving overall stability. For bilateral symptoms, an over-the-top approach (unilateral laminotomy for bilateral decompression) may be considered, although it requires advanced endoscopic proficiency.Intraoperative safety is further influenced by physiological factors; for instance, the irrigation pressure and temperature used during endoscopy may correlate with postoperative neck pain [13]. To mitigate risks, neurophysiological monitoring can be combined with the keyhole technique, providing the safety benefits of local anesthesia (nerve monitoring) with the patient comfort of general anesthesia [16]. Furthermore, emerging technologies like Augmented Reality (AR) are poised to revolutionize this field by providing real-time visualization of extra-canalicular structures, thereby improving the accuracy for beginners and reducing surgical risks.Despite the promising clinical outcomes, several critical limitations of this study must be acknowledged. First, the retrospective and single-center nature of the study may introduce selection bias. Second, the small sample size (N = 40) and the brief 6-month follow-up severely restrict the statistical power of the study. Specifically, the subgroup analysis (isolated foraminotomy vs. combined discectomy) lacks the statistical power required to claim true clinical “equivalence”; it merely indicates that no significant differences were observed within this limited cohort. Third, and most importantly, this study lacks a control group. Without a direct comparison to alternative and widely accepted surgical approaches—such as Anterior Cervical Discectomy and Fusion (ACDF) or traditional open posterior foraminotomy—the relative efficacy and safety of the endoscopic keyhole technique cannot be definitively established. Finally, the 6-month follow-up period is relatively short and insufficient to assess long-term outcomes. Future prospective, multicenter randomized controlled trials with larger cohorts and extended follow-up periods are essential to assess long-term durability, including late recurrence, adjacent segment disease, and delayed spinal instability, as well as to directly compare this technique with other standard treatments.

Supporting information

S1 Data. Supplementary information.

(XLSX)

pone.0359633.s001.xlsx^{(12.2KB, xlsx)}

Abbreviations

CT: Computed tomography
MRI: Magnetic Resonance Imaging
SD: Standard deviation
CSR: Cervical spondylotic radiculopathy
ACDF: Anterior cervical discectomy and fusion
VAS: Visual Analog Scale
JOA: Japanese Orthopedic Association
NDI: Neck Disability Index (NDI)

Data Availability

All data are in the paper and Supporting Information files.

Funding Statement

The study was supported by Yunnan Fundamental Research Projects, No. 202401AY070001-158 and Kunming Health Science and Technology Talent Cultivation Project, 2025-SW-040 awarded to the first author. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Partly

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2. Has the statistical analysis been performed appropriately and rigorously? -->?>

Reviewer #1: Yes

Reviewer #2: No

Reviewer #3: Yes

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3. Have the authors made all data underlying the findings in their manuscript fully available??>

The PLOS Data policy

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

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4. Is the manuscript presented in an intelligible fashion and written in standard English??>

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

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Reviewer #1: This study describes a technical note on a retrospective case series of endoscopic posterior keyhole decompression/foraminotomy +/- medial facetectomy. This is an area of ongoing active research and this article adds to the body of literature demonstrating that posterior endoscopic cervical foraminotomy is a safe technique. The strengths of the article lie in the figures which show an excellent demonstration of the posterior keyhole bony removal, along with the subgroup analysis comparing discectomy versus no-discectomy patients. This area particularly may help guide future clinical care as it shows minimal additional benefit with discectomy compared to foraminotomy alone. There are, however, a few areas that the article should be improved in prior to publication.

Introduction:

- The introduction should go into more detail involving the background of the field. In the discussion the authors site the Ruetten study along with 2 others but there are many such studies that should be highlighted as this has been an increasing area of publication over the last 20 years. Some combination of the following studies along with a description of their findings should be used in the introduction to highlight the divide in the field between posterior cervical foraminotomy and acdf for treatment of radiculopathy. See below for a list of such studies. Not all need to be referenced individually, but citation of the field can help improve this publications standalone value.

1. Yang JS, Chu L, Chen L, Chen F, Ke ZY, Deng ZL. Anterior or posterior approach of full-endoscopic cervical discectomy for cervical intervertebral disc herniation? A comparative cohort study. Spine (Phila Pa 1976). 2014;39:1743–50.

2. Kim KT, Cho DC, Sung JK, Kim YB, Kim DH. Comparative analysis between total disc replacement and posterior foraminotomy for posterolateral soft disc herniation with unilateral radiculopathy: clinical and biomechanical results of a minimum 5 years follow-up. J Korean Neurosurg Soc. 2017;60:30–9.

3. Ruetten S, Komp M, Merk H, Godolias G. Full- endoscopic anterior decompression versus conventional anterior decompression and fusion in cervical disc herniations. Int Orthop. 2009;33:1677–82.

4. Park YK, Moon HJ, Kwon TH, Kim JH. Long-term outcomes following anterior foraminotomy for one- or two-level cervical radiculopathy. Eur Spine J. 2013;22:1489–96.

5. Kim KT, Kim YB. Comparison between open procedure and tubular retractor assisted procedure for cervical radiculopathy: results of a randomized controlled study. J Korean Med Sci. 2009;24:649–53.

6. Ruetten S, Komp M, Merk H, Godolias G. Full- endoscopic cervical posterior foraminotomy for the operation of lateral disc herniations using 5.9-mm endoscopes: a prospective, randomized, controlled study. Spine (Phila Pa 1976). 2008;33:940–8.

7. Won S, Kim CK, Chung CK, et al. Clinical outcomes of single-level posterior percutaneous endoscopic cervical foraminotomy for patients with less cervical lordosis. J Minim Invasive Spine Surg Tech. 2016;1:11–7.

8. Kim CH, Shin KH, Chung CK, Park SB, Kim JH. Changes in cervical sagittal alignment after single- level posterior percutaneous endoscopic cervical diskectomy. Global Spine J. 2015;5:31–8.

9. Kim CH, Kim KT, Chung CK, et al. Minimally invasive cervical foraminotomy and diskectomy for laterally located soft disk herniation. Eur Spine J. 2015;24:3005–12. 3

10. Kim CH, Chung CK, Kim HJ, Jahng TA, Kim DG. Early outcome of posterior cervical endoscopic discectomy: an alternative treatment choice for physically/socially active patients. J Korean Med Sci. 2009;24:302–6.

11. Ruetten S, Komp M, Merk H, Godolias G. A new full-endoscopic technique for cervical posterior foraminotomy in the treatment of lateral disc herniations using 6.9-mm endoscopes: prospective 2-year results of 87 patients. Minim Invasive Neurosurg. 2007;50:219–26.

Materials and Methods

- Pg. 4 Line 155-157 “Additionally, depending on the severity of residual symptoms, adjunct therapies including osmotic diuretics, low-dose glucocorticoids, or neurotrophic agents”

o The use of steroids can be a major confounding factor in the early outcomes for patients. Can the authors comment to whether any topical steroids were used? Also did all patients receive a dose of steroids for post operative nausea/vomiting or was this on a case by case basis?

Quantitative Evaluation

- Pg. 5, line 210-212 “Intergroup analysis revealed no statistically significant differences between these two subgroups regarding operative time, intraoperative blood loss, or hospitalization costs (all P > 0.05).”

o This is the most unique feature of this paper. Notably a few additional details should be provided regarding differences in baseline imaging when discectomy was pursued versus when it was not. It would be important for the readers to know whether the indications for the decompression were the same in both groups, and would be helpful if a figure with a representative MRI from each group was shown to help guide the reader/surgeon in the decision making process outlined.

Figures

- Ideally a figure in between figure 2 and 3 a figure can be added that can demonstrate the different technical steps of the procedure such as with Introducing the endoscope at V point, clearing of soft tissue with the bipolar/punch, Identifying the V point, Utilizing the diamond burr/drill for foraminotomy, Dissection/removal of ligamentum flavum. These steps have been published before and are not of critical importance but help increase the reliability of the findings as they standardize the surgical approach.

Reviewer #2: This retrospective case series (n=40) evaluates endoscopic posterior "keyhole" decompression for cervical radiculopathy and reports favorable short-term outcomes with no correlation between decompression extent and clinical improvement. The clinical technique and core message are of interest, but the manuscript requires revisions.

1. The manuscript states that cervical radiculopathy falls under "degenerative cervical myelopathy (DCM)" terminology. This should be corrected or removed.

2. "volume of excised nucleus pulposus" is stated to show no correlation with outcome, but no methodology for measuring or analyzing this variable appears anywhere in the Methods or Results.

3. Inconsistent study period across sections. Please address.

4. Abstract/Methods state decompression parameters were quantified via "MRI/CT," but Results only describe CT-based measurements in the imaging subgroup. Please clarify or correct.

5. Recurrence (n=2) discussed but not reported as a Result.

Reviewer #3: This retrospective case series evaluates endoscopic posterior “keyhole” decompression for single-level cervical radiculopathy and reports improvement in VAS, JOA, and NDI scores at discharge and 6 months. The topic is clinically relevant, but the manuscript requires major revision because the rationale, patient selection, statistical reporting, and conclusions are not sufficiently clear or well supported.

Introduction and background

• The statement regarding the prevalence of cervical spondylotic radiculopathy, reported as approximately 60% of cervical spondylosis cases, requires a citation.

• The introduction discusses myelopathy and ACDF, but the actual focus of the study is endoscopic posterior decompression for radiculopathy. The background should be reframed around cervical radiculopathy, posterior cervical foraminotomy, endoscopic approaches, and the specific knowledge gap this paper is trying to address.

• The authors should better explain why this study is needed. Is the main question safety, clinical efficacy, optimal decompression size, need for discectomy, or comparison with ACDF? At present, the objective is somewhat broad.

Methods

• The authors need to clarify how patients were selected for this retrospective series. It is not clear whether all eligible patients during the study period were included. Formal inclusion and exclusion criteria are needed. Although diagnostic criteria are described, the manuscript does not clearly state which patients were excluded and why.

• The manuscript should clarify who performed the radiological decompression measurements. Were these assessed by the treating surgeon, an independent spine surgeon, or a radiologist? Were assessors blinded to clinical outcomes?

Results

• The average hospital stay of 6.2 days appears high for patients undergoing endoscopic decompression for cervical radiculopathy. The authors should clarify whether this reflects local practice, insurance or health system factors, postoperative monitoring protocols, or patient comorbidity. This is important for interpreting the generalizability of the results.

• The results section needs improved organization. For example, the imaging findings section includes methodological details about how measurements were taken, which should be moved to the methods. It also includes interpretive statements that would be more appropriate for the discussion.

• The statement, “Based on preoperative pathology and surgical planning, the cohort was divided into two subgroups,” requires further explanation. The authors should specify what criteria determined whether a patient underwent foraminotomy alone versus foraminotomy with discectomy.

• Table 1 should provide exact p values rather than reporting only P < 0.05. Exact p values and confidence intervals would allow readers to better judge the magnitude and reliability of the observed improvements.

• Table 2 includes only 20 cases across C4/5, C5/6, and C6/7, whereas the full cohort includes 40 patients. The authors need to explain why only 20 patients underwent postoperative CT assessment and whether these patients differed from the remaining cohort.

• More information is needed regarding missing data and follow-up. The authors should state how many patients had complete clinical follow-up, how many had imaging follow-up, and whether any patients were excluded from specific analyses.

• The subgroup comparison between decompression alone and decompression plus nucleus pulposus removal is also underpowered. With 25 and 15 patients in each group, the lack of statistical significance does not establish equivalence between the two approaches.

Conclusions

• The conclusions are too strong for the evidence presented. This is a retrospective, single-center case series without a control group, so it cannot establish that this technique is superior or equivalent to ACDF or open posterior foraminotomy.

• The conclusion that clinical efficacy depends on targeted neural decompression rather than disc removal or wider laminoforaminotomy is not fully supported. The study does not have sufficient power or design strength to make this mechanistic claim.

• Because there is no comparison group, the manuscript should avoid drawing conclusions about ACDF beyond general background discussion.

• The follow-up period of 6 months is short, particularly for assessing recurrence, instability, delayed complications, and durability of symptom relief.

Overall, the paper addresses a relevant clinical topic, but it needs major revision with clearer framing, formal inclusion and exclusion criteria, better explanation of missing imaging data, improved statistical reporting, and more cautious conclusions.

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Reviewer #1: Yes: Pavan Upadhyayula

Reviewer #2: No

Reviewer #3: No

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PLoS One. 2026 Oct 27;21(10):e0359633. doi: 10.1371/journal.pone.0359633.r002

Author response to Decision Letter 1

27 Aug 2026

Dear Dr. Dean Chou,

Academic Editor, PLOS ONE

Thank you and the reviewers for the thorough and constructive evaluation of our manuscript titled “[Efficacy evaluation of the cervical posterior “keyhole technique” in the treatment of cervical radiculopathy: A retrospective case series]”. We highly appreciate the time and effort you have dedicated to providing insightful feedback.

We have carefully revised the manuscript according to all comments. Below, we provide a point-by-point response to the Editor and the Reviewers. Changes in the revised manuscript are highlighted in the “Revised Manuscript” file.

________________________________________

Part I: Response to Journal Requirements (Editor’s Comments)

1. Style Requirements:

Response: We have reviewed PLOS ONE’s style templates and updated our manuscript’s formatting, including file naming, heading styles, and paragraph formatting, to ensure full compliance.

2, 3, & 4. Funding Information, Discrepancies, and Role of Funder:

Response: We apologize for the incorrect placement and discrepancies. We have completely removed all funding-related text from the Acknowledgments section. In the Cover Letter, we have provided the updated and matching grant numbers for the Funding Statement.

5. Data Availability:

Response: We confirm that all de-identified minimal underlying datasets necessary to replicate our study findings will be made freely accessible upon acceptance.

6. ORCID iD:

Response: The corresponding author’s ORCID iD has been successfully validated in the Editorial Manager system.

7 & 8. Author Name Correction (Ruohui Tang):

Response: We apologize for the typographical error. We have amended the author’s name to “Ruohui Tang” in both the Editorial Manager system and the manuscript file.

9. Ethics Statement Location:

Response: The ethics statement has been exclusively moved to the Methods section. Any mention of it in other sections has been deleted.

10. Copyrighted Images (Figure 2):

Response: All intraoperative images presented in this figure are original photographs taken personally by the authors during the surgical procedures.

11. Tables:

Response: All tables have been inserted directly into the main manuscript text immediately following the paragraph in which they are first cited, and individual table files have been removed.

________________________________________

Part II: Response to Reviewer #1

General Comment: This study describes a technical note… The strengths of the article lie in the figures… There are, however, a few areas that the article should be improved in prior to publication.

Response: We sincerely thank the reviewer for recognizing the clinical value of our study and the quality of our figures. Your constructive suggestions have significantly improved the depth and standalone value of our manuscript.

Comment 1 (Introduction): The introduction should go into more detail involving the background of the field… Some combination of the following studies (Yang JS, Kim KT, Ruetten S) along with a description of their findings should be used in the introduction to highlight the divide in the field between posterior cervical foraminotomy and acdf…

Response: We have expanded the Introduction to better reflect the historical divide and ongoing debate between ACDF and posterior cervical foraminotomy (PCF). We have incorporated the excellent studies you suggested (Yang JS, Kim KT, and Ruetten S) to highlight the biomechanical and clinical differences, thereby better establishing the background for our research. (Page [3], Lines [88-93]).

Comment 2 (Methods - Steroids): The use of steroids can be a major confounding factor… Can the authors comment to whether any topical steroids were used? Also did all patients receive a dose of steroids for post operative nausea/vomiting or was this on a case by case basis?

Response: Thank you for raising this important point. We did not use local steroids during the procedure. Regarding systemic steroids, they were not used routinely. Specifically, only three patients who experienced limb numbness within 24 hours postoperatively received an intravenous administration of 60 mg methylprednisolone to relieve nerve root edema. We have added this detail to the Methods and Results sections to ensure complete transparency. (Page [5], Lines [180-183]).

Comment 3 (Quantitative Evaluation): It would be important for the readers to know whether the indications for the decompression were the same in both groups, and would be helpful if a figure with a representative MRI from each group was shown to help guide the reader/surgeon in the decision making process outlined.

Response: We appreciate this insightful comment. In our practice, the decision to perform a discectomy is based on preoperative MRI findings combined with intraoperative exploration. If the posterior annulus fibrosus remains intact and the nerve root tension decreases significantly after microscopic bony decompression, the disc is not excised. We believe that precise posterior bony and ligamentous decompression is the key to alleviating nerve root compression symptoms. We have detailed these surgical indications in the Methods section.

Comment 4 (Figures): Ideally a figure in between figure 2 and 3 a figure can be added that can demonstrate the different technical steps of the procedure…

Response: We strongly agree that a step-by-step intraoperative figure increases the reliability and standardization of the procedure. Accordingly, we have updated Figure 2 by incorporating a series of intraoperative endoscopic images, including the identification of the V-point, utilizing the burr for foraminotomy, removing the ligamentum flavum, and exposing the nerve root.

________________________________________

Part III: Response to Reviewer #2

General Comment: The clinical technique and core message are of interest, but the manuscript requires revisions.

Response: We thank the reviewer for the positive assessment of our core message and for the meticulous review. We have addressed all your concerns below.

Comment 1: The manuscript states that cervical radiculopathy falls under “degenerative cervical myelopathy (DCM)” terminology. This should be corrected or removed.

Response: We apologize for the inaccurate terminology. We have removed the term “degenerative cervical myelopathy (DCM)” and corrected the text to specifically focus on “cervical spondylotic radiculopathy (CSR)” throughout the manuscript to avoid confusion. (Page [2], Lines [80-83]).

Comment 2: “volume of excised nucleus pulposus” is stated to show no correlation with outcome, but no methodology for measuring or analyzing this variable appears anywhere…

Response: We apologize for this expression error. We did not accurately measure the exact volume of the excised nucleus pulposus. Our intended meaning was to compare clinical outcomes based on “whether discectomy was performed or not.” We have corrected this phrasing throughout the manuscript. (Page [2], Lines [65-67]).

Comment 3: Inconsistent study period across sections. Please address.

Response: We apologize for the typo. We have carefully checked and unified the study period dates across the Abstract, Methods, and Results sections to ensure absolute consistency.

Comment 4: Abstract/Methods state decompression parameters were quantified via “MRI/CT,” but Results only describe CT-based measurements in the imaging subgroup. Please clarify or correct.

Response: We apologize for the inaccurate expression. We only quantified the parameters of bony decompression, which was strictly performed using postoperative CT scans. The mention of MRI for quantitative morphological measurement was an error, and we have corrected this in the Abstract and Methods.

Comment 5: Recurrence (n=2) discussed but not reported as a Result.

Response: Thank you for pointing out this omission. We have now explicitly reported in the Results section that two patients experienced a recurrence of symptoms and subsequently underwent Anterior Cervical Discectomy and Fusion (ACDF) surgery. (Page [5], Lines [211-213]).

________________________________________

Part IV: Response to Reviewer #3

General Comment: The topic is clinically relevant, but the manuscript requires major revision because the rationale, patient selection, statistical reporting, and conclusions are not sufficiently clear or well supported.

Response: We express our sincere gratitude for your rigorous and highly professional critique. Your comments have prompted us to significantly improve the methodology reporting, statistical presentation, and the objective tone of our conclusions.

Comment 1 (Introduction): Prevalence of CSR (60%) requires a citation. Refocus background on radiculopathy, not ACDF/myelopathy. Clarify the specific knowledge gap and objective.

Response: Following your advice, we have extensively rewritten the Introduction. We agree that the introduction was too broad. We have completely restructured the Introduction to focus strictly on cervical radiculopathy, posterior cervical foraminotomy, and endoscopic approaches. We have removed the distracting discussions regarding myelopathy. Furthermore, we clearly stated our primary objective at the end of the introduction: to evaluate the clinical efficacy and safety of this technique, and specifically to investigate whether the extent of bony decompression or the addition of discectomy provides further clinical benefits. (Page [2], Lines [80-83, 95-105]).

Comment 2 (Methods - Patient Selection): Formal inclusion and exclusion criteria are needed…

Response: We have added a dedicated sub-section in the Methods titled “Patient Selection,” clearly outlining the formal Inclusion criteria (e.g., single-level unilateral CSR, failure of conservative treatment > 6 weeks) and Exclusion criteria (e.g., cervical instability, myelopathy, severe calcified disc, previous cervical surgery). (Page [3], Lines [118-125]).

Comment 3 (Methods - Radiology): Clarify who performed the radiological decompression measurements… Were assessors blinded?

Response: We have clarified in the Methods section that all radiological measurements were performed independently by two spine surgeons who were not involved in the surgical procedures and were strictly blinded to the patients’ clinical outcomes. (Page [5], Lines [191-194]).

Comment 4 (Results - Hospital Stay): The average hospital stay of 6.2 days appears high… clarify whether this reflects local practice, insurance…

Response: Thank you for allowing us to clarify this. The relatively long hospital stay was not due to postoperative complications or delayed recovery. Instead, it was strictly due to the time required for routine preoperative examinations and scheduling delays at our local hospital (for example, scheduling an MRI scan typically requires a 1-to-3 day waiting period as an inpatient). We have added a brief explanation in the Discussion section to contextualize this finding for international readers. (Page [6-7], Lines [261-268]).

Comment 5 (Results - Organization): Move methodological details to methods. Interpretive statements to discussion.

Response: We have thoroughly reorganized the Results section. All descriptions of how CT measurements were taken have been moved to the Methods section, and subjective interpretations have been relocated to the Discussion section.

Comment 6 (Results - Subgroups): Specify what criteria determined whether a patient underwent foraminotomy alone versus foraminotomy with discectomy.

Response: In our practice, the decision to perform a discectomy is based on preoperative MRI findings combined with intraoperative exploration. If the posterior annulus fibrosus remains intact and the nerve root tension decreases significantly after microscopic bony decompression, the disc is not excised. We believe that precise posterior bony and ligamentous decompression is the key to alleviating nerve root compression symptoms. We have detailed these surgical indications in the Methods section. (Page [4], Lines [163-169]).

Comment 7 (Results - Table 1 P-values): Table 1 should provide exact p values rather than reporting only P < 0.05.

Response: We have updated Table 1 (and all text) to report exact P-values to allow readers to better judge the magnitude of the improvements.

Comment 8 (Results - Only 20 post-op CTs): Explain why only 20 patients underwent postoperative CT assessment and whether these patients differed from the remaining cohort.

Response: This is a crucial point. The lack of postoperative CT for the remaining 20 patients was deeply rooted in our local clinical reality. Primarily, due to rapid postoperative discharge (often on postoperative day 1 or 2), the window to schedule scans was narrow. More importantly, under the strict health insurance payment policies (DRG/DIP systems in China), routine postoperative CTs are often not fully covered. This additional financial burden led to direct patient refusal, particularly when their radiating pain had already significantly relieved immediately after surgery. There were no demographic or baseline clinical differences between the 20 patients who received scans and the 20 who did not. We have explicitly added this explanation to the Results. (Page [6], Lines [223-227]).

Comment 9 (Results - Missing Data): State how many patients had complete clinical follow-up, imaging follow-up…

Response: Thank you for this insightful observation. We chose 6 months postoperatively as the standard endpoint for our primary statistical analysis because the clinical data for all 40 included patients was most complete and comprehensive at this specific time point. In our real-world clinical practice, although some patients have been followed up for more than a year, others did not return for outpatient evaluations after 6 months (often due to satisfactory symptom relief and the inconvenience of traveling back to the hospital). To ensure the consistency and reliability of our statistical analysis, we strictly utilized the complete 6-month dataset. However, we completely agree that the lack of uniform long-term follow-up data is a shortcoming. We have now added this point as a limitation in the Discussion section. (Page [8], Lines [316-319]).

Comment 10 (Results - Underpowered Subgroup): With 25 and 15 patients… lack of statistical significance does not establish equivalence.

Response: We completely agree with your insightful critique. We acknowledge that the subgroup comparison (n=25 vs. n=15) is significantly underpowered. We have revised the Discussion section to explicitly state that the lack of statistical significance does not establish clinical equivalence between the two approaches, and we have reframed our discussion as a preliminary clinical observation rather than a definitive conclusion. (Page [7], Lines [272-277]).

Comment 11, 12, 13, 14 (Conclusions): Conclusions are too strong… mechanistic claim not supported… avoid ACDF conclusions… short follow-up.

Response: Thank you for pointing this out. We have carefully reviewed the manuscript and toned down our conclusions throughout. We have removed any comparative claims suggesting superiority or equivalence to ACDF or open posterior foraminotomy. ACDF is now only mentioned strictly as background context. We also explicitly stated in the Limitations section that the lack of a control group prevents us from making any direct comparisons regarding efficacy and safety.

We agree that our study design and statistical power are insufficient to make this mechanistic claim. We have modified the Discussion section to soften this point. We now state that while our findings align with the concept of targeted decompression, the study does not have sufficient strength to definitively claim that clinical efficacy relies solely on targeted neural decompression rather than wider laminoforaminotomy.

We fully acknowledge that 6 months is a short follow-up period, which limits our ability to evaluate long-term outcomes. We have explicitly added this to the Limitations section, specifically highlighting that a 6-month follow-up is insufficient for assessing late recurrences, delayed spinal instability, delayed complications, and the long-term durability of symptom relief.

________________________________________

We believe that the manuscript has been substantially improved thanks to the reviewers’ comments. We hope that the revised manuscript now meets the high standards for publication in PLOS ONE.

Thank you again for your time and consideration.

Sincerely,

Zhaowen Zhou

Attachment

Submitted filename: Response.docx

pone.0359633.s002.docx^{(26.9KB, docx)}

PLoS One. doi: 10.1371/journal.pone.0359633.r003

Decision Letter 1

Dean Chou

14 Sep 2026

Dear Dr. Zhou,

Thank you for submitting your manuscript to PLOS One. After careful consideration, we feel that it has merit but does not fully meet PLOS One’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

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Academic Editor

PLOS One

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Additional Editor Comments:

I would like to review figure 2 which they made substantial revisions to, to provide a step by step explanation of the steps of the surgical procedure.

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Reviewers' comments:

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Reviewer #2: All comments have been addressed

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Reviewer #3: Yes

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Reviewer #2: The authors have appropriately addressed all of the concerns raised in the prior review. The revisions have improved the accuracy and clarity of the manuscript, and no further comments are warranted.

Reviewer #3: The authors have adequately addressed the concerns raised in the previous review, and the manuscript has been substantially improved. The research question, inclusion/exclusion criteria, indications for foraminotomy versus discectomy, and radiological assessment have been appropriately clarified. The issue of incomplete postoperative imaging has also been explained and acknowledged as a limitation.

The Results and Discussion have been appropriately revised, particularly regarding the underpowered subgroup analysis and the avoidance of claims of equivalence or superiority. The study limitations are now adequately presented and appropriately contextualized.

Overall, I believe the revisions satisfactorily address the prior concerns, and I have no further substantive comments.

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PLoS One. 2026 Oct 27;21(10):e0359633. doi: 10.1371/journal.pone.0359633.r004

Author response to Decision Letter 2

14 Sep 2026

Manuscript ID: PONE-D-26-28826R1

Title: Efficacy evaluation of the cervical posterior “keyhole technique” in the treatment of cervical radiculopathy: A retrospective case series

Dear Dr. Dean Chou and the Reviewers,

Thank you for your positive feedback and for reviewing our revised manuscript. We are thrilled to hear that both reviewers are satisfied with our previous revisions. We have carefully addressed the Academic Editor’s additional request regarding Figure 2, as well as the Journal Requirements regarding the reference list. Please find our point-by-point responses below.

________________________________________

Reply to Journal Requirements:

Journal Requirement: Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text…

Response:

We have carefully reviewed and verified our entire reference list item by item. We confirm that all cited references are highly relevant to this study, and no irrelevant literature has been cited. Furthermore, we have strictly checked our bibliography against current databases and can confirm that none of the cited papers have been retracted. The reference details have been thoroughly updated and completed to ensure full compliance with the journal’s formatting guidelines.

________________________________________

Reply to the Academic Editor:

Editor’s Comment: I would like to review figure 2 which they made substantial revisions to, to provide a step by step explanation of the steps of the surgical procedure.

Response:

Thank you for this constructive suggestion. We fully agree that a clear, step-by-step explanation significantly improves the readability and practical value of our manuscript.

In this revision, we have updated the figure legend for Figure 2 and the corresponding text in the manuscript to provide a detailed, step-by-step explanation of the posterior cervical “keyhole technique” under endoscopy.

Specifically, the step-by-step explanation for the intraoperative procedures (Figure 2B1-B4) has been added as follows:

• Step 1 (Fig. 2B1): After confirming the surgical level via fluoroscopy, the working channel and endoscope are sequentially inserted. Under endoscopic visualization, the soft tissues on the surface of the lamina and lateral mass joint are cleared. The “V-point” (indicated by a star) is exposed laterally through the interlaminar space, and a high-speed burr is used to drill the bone at the V-point.

• Step 2 (Fig. 2B2): A Kerrison rongeur is used to bite off the residual thin layer of bone, further exposing the V-point.

• Step 3 (Fig. 2B3): The lateral edge of the ligamentum flavum and the dorsal membranous structure of the nerve root are exposed. After identifying the nerve root, a partial resection of the ligamentum flavum is performed to further decompress the dorsal aspect of the nerve root canal.

• Step 4 (Fig. 2B4): A nerve hook is used to gently retract the nerve root. The axilla and shoulder regions of the nerve root are carefully explored, and the herniated disc material (nucleus pulposus) is removed to achieve complete release and mobilization of the nerve root.

We have incorporated these steps into the revised manuscript (highlighted in Track Changes). We hope this detailed explanation meets your requirements and perfectly illustrates the surgical procedure.

________________________________________

Reply to Reviewer #2:

Reviewer #2’s Comment: The authors have appropriately addressed all of the concerns raised in the prior review. The revisions have improved the accuracy and clarity of the manuscript, and no further comments are warranted.

Response:

Thank you very much for your time, expertise, and positive evaluation of our manuscript. Your constructive comments during the previous round of review have greatly improved the quality of our paper.

________________________________________

Reply to Reviewer #3:

Reviewer #3’s Comment: Overall, I believe the revisions satisfactorily address the prior concerns, and I have no further substantive comments.

Response:

We sincerely appreciate your thorough review and encouraging comments. We are glad that our revisions have met your expectations. Thank you for your valuable contribution to improving our study.

Attachment

Submitted filename: Response to Reviewers.docx

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PLoS One. doi: 10.1371/journal.pone.0359633.r005

Decision Letter 2

Dean Chou

17 Sep 2026

Efficacy evaluation of the cervical posterior “keyhole technique” in the treatment of cervical radiculopathy: A retrospective case series

PONE-D-26-28826R2

Dear Dr. Zhou,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

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Kind regards,

Dean Chou, MD

Academic Editor

PLOS One

Additional Editor Comments (optional):

Reviewers' comments:

PLoS One. doi: 10.1371/journal.pone.0359633.r006

Acceptance letter

Dean Chou

PONE-D-26-28826R2

PLOS One

Dear Dr. Zhou,

I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS One. Congratulations! Your manuscript is now being handed over to our production team.

At this stage, our production department will prepare your paper for publication. This includes ensuring the following:

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PLOS One Editorial Office Staff

on behalf of

Dr. Dean Chou

Academic Editor

PLOS One

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

S1 Data. Supplementary information.

(XLSX)

pone.0359633.s001.xlsx^{(12.2KB, xlsx)}

Attachment

Submitted filename: Response.docx

pone.0359633.s002.docx^{(26.9KB, docx)}

Attachment

Submitted filename: Response to Reviewers.docx

pone.0359633.s003.docx^{(19.2KB, docx)}

Data Availability Statement

All data are in the paper and Supporting Information files.

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PERMALINK

Efficacy evaluation of the cervical posterior “keyhole technique” in the treatment of cervical radiculopathy: A retrospective case series

Ruohui Tang

Jin Yin

Zhixiang Zhang

Zichao Chen

Yixin Li

Zhaowen Zhou

Roles

Abstract

Study design

Objective

Summary of background data

Methods

Results

Conclusions

Introduction

Materials and methods

General data and patient selection

Fig 1. A. 52-year-old male, left-sided disc herniation at C6/7; B 66-year-old male, right-sided disc herniation at C6/7; C. 37-year-old male, left-sided disc herniation at C6/7; D. 69-year-old female, left-sided disc herniation at C5/6.

Diagnostic criteria

Surgical method

Fig 2. A. Lateral midline puncture positioning, intraoperative confirmation of puncture segment, establishment of working channel, and postoperative appearance with a 1.0 cm incision.

Perioperative management and outcome measures

Statistical methods

Results

Perioperative data

Table 1. VAS, JOA, and NDI scores at the preoperative, before-discharge, and 6-month postoperative assessments. Values are mean ± SD. The P values refer to paired comparisons between the preoperative score and the score at the corresponding later time point.

Imaging findings

Table 2. Segment distribution and segment-specific measurements of the maximum decompression transverse diameter, puncture depth, and center-point offset in the cervical spine. The number of cases is shown for each segment.

Table 3. Correlations between the decompression transverse diameter and VAS, JOA, and NDI scores. The shared heading above the right-hand columns denotes the decompression transverse diameter (mm).

Fig 4. Axial CT image from postoperative follow-up.

Quantitative evaluation

Table 4. Comparison of perioperative outcomes and JOA scores between decompression alone and decompression combined with nucleus pulposus removal. Values are mean ± SD. F and P values report between-group comparisons for each variable.

Discussion

Supporting information

Abbreviations

Data Availability

Funding Statement

References

Decision Letter 0

Dean Chou

Roles

Author response to Decision Letter 1

Decision Letter 1

Dean Chou

Roles

Author response to Decision Letter 2

Decision Letter 2

Dean Chou

Roles

Acceptance letter

Dean Chou

Roles

Associated Data

Supplementary Materials

Data Availability Statement

ACTIONS

PERMALINK

RESOURCES

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