Can the efficacy of bone wax sealing method in dealing with cerebrospinal fluid leakage during ACDF be alternative to that of dural patch repair method?

Abstract

Objective

Anterior cervical discectomy and fusion (ACDF) is an important treatment for cervical degenerative diseases and trauma. Cerebrospinal fluid (CSF) leakage caused by intraoperative dural injury is a rare but clinically significant complication. The current mainstay approach involves dural repair using patches and fibrin glue. The bone wax sealing method is a novel technique for managing intraoperative CSF leakage during ACDF. This study aims to analyse the effectiveness of bone wax sealing in treating intraoperative CSF leakage.

Methods

A retrospective analysis was conducted on consecutive patients who underwent ACDF and were identified as having intraoperative CSF leakage between January 2020 and October 2025. Patients were divided into two groups according to the primary method used to manage the leak: the patch repair group and the bone wax sealing group. In the patch repair group, a dural patch was applied over the dural tear and secured with fibrin glue. In the bone wax sealing group, bone wax was used to completely occlude the anterior interbody space around the interbody cage, thereby physically isolating the prevertebral space from the intervertebral space. Clinical outcomes were assess between the two groups.

Results

Among 1,311 ACDF patients, 23 cases (1.75%) experienced intraoperative cerebrospinal fluid (CSF) leakage resulting from iatrogenic dural tear. The maximum diameter of all tears was ≤ 5 mm. Twelve cases were managed with dural patch repair (using dural substitute and fibrin glue), and 11 with bone wax sealing. In the dural patch group, 10 cases achieved successful repair, while 2 required additional lumbar drainage due to persistent leakage. No failures were observed in the bone wax group, and no case developed other postoperative complications. In two groups, no safety-related comorbidities were identified. The cost of the patch and adhesive was ¥3,953, whereas the bone wax costed only ¥18, indicating a significant difference.

Conclusion

The bone wax sealing method is easy to operate, simple, and highly cost-effective. In appropriately selected cases (small dural tears and complete hemostasis), it may be considered a viable alternative to dural patch repair.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12893-026-03944-7.

Introduction

Anterior cervical discectomy and fusion (ACDF) is a well - established surgical technique for treating the majority of cervical degenerative conditions and trauma. It provides effective neural decompression, relative safety, and a low complication rate. Cerebrospinal fluid (CSF) leakage resulting from incidental durotomy is a rare yet troublesome complication, with an incidence ranging from 0.05% to 4.2% [1–7]. Some studies have indicated that most CSF leaks resolve spontaneously within six months without reoperation or lumbar drainage [8]; but untreated leaks may lead to headache, neck swelling, dysphagia, neurologic deficits, meningocele, fistula formation, poor wound healing, arachnoiditis, or infection [1, 2, 9, 10]. These complications prolong hospital stay and increase costs [11], and decrease patient satisfaction. Therefore, it should still be treated promptly at an early stage.

Currently, the main methods for dealing with CSF leakage during ACDF include direct dural suturing, dural patch repair, lumbar drainage, and observation [12, 13]. Direct repair is theoretically the most reliable, but it is rarely chosen due to the difficult operation in the narrow intervertebral space. The observation method essentially waits for the spontaneous closure of the dural tear or the cerebrospinal fluid leakage channel, which takes a long time. At present, the major treatments in clinical practice are patch repair and lumbar drainage. The dural patch repair method has the risk of spinal cord compression [14], and lumbar drainage will significantly increase the patient’s length of hospital stay [15]. In view of this, we developed a method of using bone wax to seal cerebrospinal fluid leakage during ACDF. This study retrospectively analyzed the efficacy of the bone wax sealing method and the dural patch repair method for dealing with cerebrospinal fluid leakage found during ACDF, aiming to provide a reference for clinical practice.

Methods

Patients

This study received approval from the Institutional Review Board (Approval No. KY2022-012-01). Consecutive patients who underwent ACDF and were confirmed with intraoperative CSF leakage between January 2020 and October 2025 were retrospectively identified through medical records and imaging systems.

Inclusion criteria

1) Patients who underwent ACDF surgery.

2) Patients with CSF leakage detected during the surgery and treated with direct repair using a dural patch or bone wax occlusion.

3) Patients who had at least 3 - month follow - up.

Exclusion criteria

1) Patients who underwent posterior surgery and experienced cerebrospinal fluid (CSF) leakage during the posterior surgery.

2) Patients with CSF leakage that was not detected during the surgery but occurred postoperatively.

Surgical techniques

Dural patch repair

As described in the literature [16], a dural patch (Tian Xin Fu^®, China) was trimmed to be slightly larger than the dural defect (2–3 mm larger than the tear) and affixed to the dura using fibrin glue (Fig. 1). If CSF leakage persisted, the original patch was removed and reattached, or additional patches were applied (typically no more than two layers to avoid spinal cord compression). After confirming a watertight closure, the interbody cage was implanted and secured with a plate or screws. A surgical drainage tube was placed and maintained for 24 h. If CSF was observed in the drainage, lumbar drainage was initiated for 5 days, and the surgical drain was left in place for 72 h.

Fig. 1.

Patch repair: the patch was adhered to the dural tear site with glue. The white arrow indicated the bulging dural sac after decompression, and the black arrow indicated the dural patch

Bone wax sealing

Bone wax (ETHICON^®, Johnson & Johnson, USA) was used. After completion of decompression and achievement of hemostasis at the posterior intervertebral space, a gelatin sponge was optionally placed over the dural tear. The interbody cage was then implanted, and bone wax was applied to fully seal the anterior interbody space around the cage—including the area beneath the medial border of the longus colli muscles (Fig. 2). Excess wax was removed, and fixation was performed using a plate or screws. Postoperative incisional drainage and lumbar drainage protocols were identical to those used in the patch group.

Fig. 2.

Bone wax sealing: following decompression and cage implantation, the cage and the surrounding space were completely sealed with bone wax. The white arrow indicated the bone wax , while the black arrow represented the cage

Outcome assessment

Effective management was defined according to Woodroffe [17] as follows: (1) absence of low intracranial pressure symptoms (e.g., headache, nausea, and dizziness); (2) no CSF leakage from the surgical wound or drain, and no fluctuant mass after drain removal; and (3) no clinical or radiological evidence of meningocele.

Statistical analysis

Statistical analysis was conducted using IBM SPSS Statistics 28.0 (IBM, USA). Between two groups, efficiency was compared using Fisher’s exact test (two-tailed). Material costs were compared by means of the Mann–Whitney U test. A P value less than or equal to 0.05 was regarded as statistically significant. If sample size was small, descriptive statistics were applied. The effectiveness rate for each group was calculated as the proportion of patients with effective outcome, along with the corresponding exact binomial (Clopper–Pearson) 95% confidence interval (CI) to indicate the range of plausible true rates.

Results

Among 1,313 ACDF procedures, 23 cases (1.75%) were complicated by intraoperative CSF leakage(Table 1). All the dural tears were iatrogenic: they occurred during high-speed drilling or use of a rongeur to remove osteophytes or ossified posterior longitudinal ligaments (11 cases), during resection of the posterior longitudinal ligament in patients with ossification of the posterior longitudinal ligament (OPLL) (3 cases), or during separation of dural adhesions (9 cases).The location, size, and cause of the dural ruptures were listed in (Table 2).

Table 1.

Treatment outcomes in the two groups*

Group	Effective Rate	95% CI
Dural patch	83%(10/12)	51.6%–97.9%
Bone wax	100%(11/11)	69.2%–100.0%

* no inferential comparison was performed due to small sample size

Table 2.

The size, location and cause of the dural rupture

Group	Size		Location		Cause of the tears
	≦ 5 mm	> 5 mm	Central	Fringe	Drill	Rongeur	Dissector
Dural patch	12	0	2	10	6	4	2
Bone wax	11	0	3	8	5	5	1
tolal	23	0	8	15	11	9	3

Twelve patients underwent dural patch repair and 11 underwent bone wax sealing. Dural patch repair was the standard intraoperative procedure for managing CSF leakage. In the bone wax sealing group, the first three cases required passive measures due to a lack of available patches, whereas the subsequent cases were the choices made by patients after they gave informed consent. All patients underwent postoperative magnetic resonance imaging(MRI) test.

In the patch group, effectiveness was achieved in 10 patients, and two patients required lumbar drainage due to persistent CSF leakage. No spinal cord compression attributable to the patch was detected in all 12 cases. The cost of the patch and adhesive per case was ¥3,953. In the bone wax group, all 11 cases of intraoperative CSF leakage were successfully maneged at one time. No case required lumbar drainage, and none exhibited clinical manifestations of CSF leakage, hematoma, or meningocele. The cost of bone wax per case was ¥18, significantly lower than that of the patch. In both groups, all wounds healed uneventfully, and no other complications were observed.

Discussion

Risk factors for CSF leakage during ACDF include patient age over 70 years, ossification of the posterior longitudinal ligament (OPLL), dural adhesions, cervical fracture, revision surgery, osteophytes, multilevel procedures, and ankylosing spondylitis [4, 18]. Among these, OPLL is identified as an independent risk factor [19]. The incidence of CSF leakage in our series (1.75%) is consistent with that reported in the literature [3–7]. With regard to the causes of dural rupture in our cases, continuous improvement of surgical skills and refinement of surgical instruments may further reduce the incidence of dural injury.

Dural patch repair

Dural patch repair with fibrin glue is the most widely used method [20, 21]. The essence of this procedure is to seamlessly affix a patch to directly cover the dural defect and preventing CSF leakage. In most cases, a single patch combined with an adhesive is sufficient to seal CSF leakage. Success depends on uniform adhesion and adequate resistance to CSF pressure. However, owing to the inherent pressure of CSF within the dural sac, CSF leakage may still occur if the patch is not firmly adhered or applied with insufficient force. To avoid iatrogenic spinal cord compression, it is recommended that no more than three layers of the patch be used [16, 21]. Theoretically, this method is applicable to CSF leakage caused by unintentional damage to the dura mater in all cases.

It must also be noted that some patients require positional adjustment [20, 22] or lumbar drainage [10, 12, 17, 20]; a few may require revision surgery [17, 23]. Additionally, because fibrin glue hardens after curing, improper handling may cause the hardened patch and adhesive to compress the spinal cord, potentially compromising spinal cord function.

Bone wax sealing

Bone wax sealing relocates the occlusion site from the dural sac surface to the anterior intervertebral space. The bone wax completely seals the anterior intervertebral space, physically isolating the prevertebral and intervertebral spaces. After occlusion with bone wax, CSF leakage is confined to the posterior intervertebral space. The pressure between the intrathecal and extrathecal CSF compartments rapidly equilibrates, eliminating any driving force for CSF flow within the spinal canal and the intervertebral space. Thus, healing of the dural defect becomes a matter of time.

The procedure of bone wax sealing is performed anterior to the intervertebral space. Compared with the patch technique, it provides a larger operative field and greater procedural convenience. Moreover, it avoids potential spinal cord compression associated with the surgery, thereby enhancing spinal cord safety.

In this study, the statistical power is limited due to the small sample size. So, it cannot compare the effectiveness of management for CSF leakage. However, the findings suggest that the bone wax sealing method is effective and- at least- clinically valuable for treating cerebrospinal fluid leakage caused by small dural tears during ACDF surgery.

Meanwhile, it may also be noted that the bone wax sealing method imposes higher demands on hemostasis in the surgical field. If hemostasis is inadequate, there will be a risk of epidural hematoma formation. On the other hand, all cases in this study involve iatrogenic small dural tears with a maximum diameter of ≤ 5 mm; thus, the probability of meningocele is relatively low. If the tear is larger, the probability of meningocele increases, and bone wax sealing becomes less suitable. In such cases, direct repair using a dural patch is more reliable than bone wax sealing. Therefore, the indications for bone wax sealing to treat intraoperative CSF leakage during ACDF are as follows: a small dural tear (maximum diameter ≤ 5 mm); complete hemostasis in intervertebral space with negligible risk of epidural hematoma.

Bone wax, composed of beeswax and softening agents, is non-absorbable and commonly used for hemostasis. Adverse effects include allergy, granuloma formation, infection, and impaired bone healing [24, 25], and these complications are dose- and site-dependent. Novel formulations may further reduce these risks [26, 27]. In our study, bone wax was used sparingly, with no related complications observed. But longer follow-up and larger cohorts are required to fully assess the safety profile of bone wax, particularly regarding osteointegration, fusion rates, and delayed complications such as granuloma formation.

Limitations

This study is a descriptive, hypothesis-generating study due to its small sample size. The nonrandomized allocation and retrospective design introduce significant selection bias, rendering the groups incomparable. Moreover, no validated outcome instrument for dural tear healing was employed. Consequently, these limitations preclude definitive validation of bone wax sealing for managing CSF leakage.

The risk of epidural hematoma exists in such case with incomplete hemostasis in the intervertebral space; moreover, bone wax is unsuitable for larger dural tears due to the risk of meningocele or neural tissue herniation.

Conclusion

The bone wax sealing method is easy to operate, simple, and highly cost-effective. In appropriately selected cases (small dural tears and complete hemostasis), it may be considered a viable alternative to dural patch repair.

Abbreviations

ACDF

Anterior cervical disectomy and fusion

CSF

Cerebrospinal fluid

CT

Computerized tomography

MRI

Magnetic resonance imaging

Authors’ contributions

All authors contributed to the study conception and design.The research ideas and methods were proposed by Xuan-Geng Deng.Material preparation, data collection were performed by Wei Cui, Yu-Liang Sun, and Wei Hou.Surgeries had been programmed by Xuan-Geng Deng, Hua-Gang Shi and Tao Gu. The first draft of the manuscript was written by Xuan-Geng Deng and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.

Funding

This work was supported by the Medical Research Fund of Sichuan Provincial Orthopedic Hospital[ZD202404].

Data availability

The datasets used and/or analysed during the current study available from the corresponding author on reasonable request.

Declarations

Ethics approval and consent to participate

This retrospective study started after obtaining permission from Sichuan Provincial Orthopedic Hospital Institutional Review Board (IRB) [No.KY2022-012-01]. All methods in this study were performed in accordance with relative guidelines and regulations. The written informed consent was signed by the patients in medical records document. The study only involved review of radiographs and medical charts, which did not disclose patient’s personal information and had been authorized by the patients.

Consent for publication

All authors agree to publish. And the patients had given written informed consent for scholar publication and scholar meeting communication about their personal and clinical data including medical images in their medical records document (Excluding personally identifiable information).

Competing interests

The authors declare no competing interests.