Use of the DTRAX Posterior Cervical Facet Joint Fusion and Distraction Device: A Case Series Including 50 Patients

Article information

J Minim Invasive Spine Surg Tech. 2024;9(Suppl 2):S126-S135

Publication date (electronic) : 2024 July 31

doi : https://doi.org/10.21182/jmisst.2024.01375

Jose J. González Sánchez^,1,2

¹Department of Neurosurgery, Clinic Barcelona, Barcelona, Spain

²Faculty of Medicine at University of Barcelona, Barcelona, Spain

Corresponding Author: Jose J. González Sánchez Department of Neurosurgery, Clinic Barcelona, Villarroel Street, 170, 08036 Barcelona, Spain Email: JJGONZAL@clinic.cat

Received 2024 April 30; Revised 2024 June 24; Accepted 2024 July 21.

Abstract

INTRODUCTION

Degenerative cervical pathology consists of a spectrum of changes resulting in cervical instability, stenosis and neural compression phenomena manifesting as pain, myelopathy, or radiculopathy. In most instances, patients improve with conservative treatment; however, if this is not feasible, the option of reparative surgical treatment arises [1].

The procedural nuances inherent to classical surgical cervical approaches encompass a diverse array of techniques tailored to specific pathologies and patient presentations. Anterior approaches, such as the anterior cervical discectomy and fusion (ACDF), offer direct access to the cervical spine, facilitating decompression and stabilization [2]. In contrast, posterior approaches, including laminectomy, laminoplasty and posterior cervical arthrodesis, provide posterior decompression and stabilization options for different cervical spine disorders [3].

While classical surgical cervical approaches have stood the test of time, they continue to evolve in response to advancements in surgical technology, imaging modalities, and understanding of cervical spine biomechanics. Concurrently, the emergence of innovative techniques such as the posterior facet fusion (DTRAX, Providence Medical Technology, Pleasanton, CA, USA) cervical procedure has augmented the armamentarium of cervical spine surgeons [4].

The DTRAX system, characterized by its minimally invasive nature and precise instrumentation, offers distinct advantages in the contemporary management of cervical pathology. Its ability to provide robust stabilization and its indirect decompression feature by minimally invasive procedure, aligns with the evolving paradigm of spine surgery. Contemporary applications of classical approaches, coupled with the benefits afforded by the DTRAX system underscores the dynamic nature of cervical spine surgery, wherein tradition and innovation converge to optimize patient outcomes [5-7].

By retrospectively analysing our series of 50 cases, we aim to contribute valuable insights into the efficacy, safety, and feasibility of utilizing DTRAX system for posterior cervical facet fusion procedures. These findings hold the potential to inform clinical decision-making, refine surgical techniques, and improve patient outcomes in the management of cervical pathology.

MATERIAL AND METHODS

The present study analysed a large retrospective series of cases involving the utilization of the DTRAX system for posterior cervical facet fusion and indirect decompression procedures between January 2017 and January 2022. The study aimed to evaluate the efficacy, safety, and feasibility of the DTRAX system in the management of cervical degenerative pathology.

RESULTS

In this retrospective study conducted between January 2017 and January 2022, we investigated the outcomes of posterior cervical facet fusion procedures using the DTRAX system in a cohort of 50 patients (Table 1). Among the participants, 21 were women (42%) and 29 were men (58%). The procedures encompassed fusion at varying levels, with 36 patients undergoing fusion at a single level (72%), 12 patients at 2 levels (24%), and 2 patients at 3 levels (4%), totalling 132 implants utilized. The average age of the patients was 44.26 years, ranging from 27 to 69 years. All patients presented with neck pain, and 23 of them also reported experiencing arm pain (46%). Following the surgical intervention, most patients were discharged within 24 hours postoperatively, with none exceeding 48 hours of hospitalization (4 patients).

Table 1.

Clinical and radiological outcomes of posterior cervical facet fusion using the DTRAX system (n=50)

Among the identified indications, pseudoarthrosis emerged as the most prevalent, observed in 16 cases (32%) within our cohort. Following closely, foraminal stenosis constituted a substantial proportion, with 14 patients (28%) undergoing fusion due to this indication. Cases of failed prosthetic implants were also prevalent, accounting for 12 cases (24%) in our study population. Additionally, adjacent segment pathology was identified as an indication for fusion in 6 patients (12%), while reinforcement of fusion at previously treated levels was required in 2 cases (4%) (Figure 1).

Figure 1.

Surgical indications: (A) ACDF pseudoarthrosis, (B) ACDR failure, (C) foraminal stenosis (on magnetic resonance imaging), (D) adjacent level degeneration, (E) fusion reinforcement. ACDF, anterior cervical discectomy and fusion; ACDR, anterior cervical discectomy and replacement.

We assessed patient’s outcome by VAS pain scores over various postoperative time points. Prior to surgery, patients reported a mean VAS score of 7.54±0.86 for neck pain and 7.61±0.78 for radicular pain (present only in 23 patients). At 24 hours postoperatively, there was a notable reduction in both neck pain means VAS score: 4.24±1.51 and radicular pain mean VAS score: 2.87 ±1.71. Subsequent follow-up assessments at 7 days, 1 month, 6 months, and 12 months revealed further improvements in pain scores. By the 7-day mark, neck pain decreased significantly to a mean VAS score of 2.86±1.05, with radicular pain also decreasing to a mean VAS score of 1.61±1.53. Over the subsequent follow-up intervals, both neck pain and radicular pain continued to decrease steadily, with mean VAS scores reaching 2.04±0.67 and 1.00±0.60 at 1 month, 1.94±0.59 and 0.70±0.56 at 6 months, and 1.64±0.60 and 0.52±0.51 at 12 months, respectively. Both axial and radicular VAS scores improvement was significant after analysis of variance (ANOVA) repeated-measures test (p<0.001) (Figure 2A and B).

Figure 2.

(A) Axial pain visual analogue scale plot during follow-up. (B) Radicular pain visual analogue scale plot during follow-up. (C) Neck Disability Index (NDI) (%) plot during follow-up.

Regarding functional outcomes following DTRAX procedures, prior to surgery, patients exhibited a mean NDI score of 50.08%±6.77%. At 7 days postoperatively there was a significant improvement in functional status, with the mean NDI score decreasing to 23.12%±2.78%. Subsequent follow-up evaluations at 1 month, 6 months, and 12 months revealed sustained improvements in functional outcomes. By the 1-month mark, the mean NDI score further decreased to 21.2%±1.71%, demonstrating continued enhancement in functional status. Although there was a slight increase in the mean NDI score at 6 months 22.12%±1.64% and 12 months 21.88%±1.69%, the overall trend indicated sustained improvement in functional outcomes compared to preoperative baseline. Overall, NDI improvement was statistically significant based on ANOVA repeated-measures test (p<0.001) (Figure 2C).

In relation with radiographic evaluation, considering all the 132 cages implanted, at the 6-month follow-up, CT scans revealed a fusion rate of 88%, indicating robust fusion outcomes within the study cohort. Subsequent evaluations at the 12-month mark demonstrated further improvement, with the fusion rate increasing to 96% (Figure 3).

Figure 3.

Example of a computed tomography scan demonstrating fusion 6 months after DTRAX implantation.

Complications associated with the utilization of the DTRAX system in our study were relatively infrequent but warrant consideration. One patient experienced transient paraesthesia following the procedure, which resolved spontaneously over time (2%). Additionally, there was one case necessitating anterior revision surgery due to foraminal bone stenosis, highlighting the potential for postoperative complications requiring further intervention (2%) (Figure 4A). Suboptimal implant positioning was observed in 2 instances (4%), 1 of them not fused at the end of the follow-up, emphasizing the importance of meticulous intraoperative placement to achieve optimal fusion outcomes (Figure 4B).

Figure 4.

(A) Case of failed foraminal decompression using DTRAX due to lateral hard disc herniation. This case required anterior surgery with decompression and fusion. In the cervical CT scan, the red circle indicates a foraminal osteophyte that blocks the intervertebral foramen, making DTRAX indirect decompression impossible and requiring direct surgical intervention to relieve nerve compression. (B) Example of DTRAX cage mispositioning.

DISCUSSION

Our study investigating the outcomes of posterior cervical facet fusion procedures utilizing the DTRAX system revealed promising results in terms of patient demographics, surgical indications, postoperative pain, functional outcomes, radiographic fusion rates, and complications. A cohort of 50 patients, predominantly comprising men, underwent fusion procedures at varying levels and indications, with the majority experiencing significant reductions in both neck and radicular pain postoperatively. Functional improvements were sustained throughout the follow-up periods, accompanied by robust fusion rates observed on radiographic evaluation and complications relatively infrequent.

The identification of surgical indications for posterior cervical facet fusion procedures, as elucidated by our study findings, aligns with existing literature on the subject. Pseudoarthrosis emerged as the most prevalent indication within our cohort, consistent with previous reports highlighting its significance as a primary indication for fusion intervention. This finding underscores the utility of posterior cervical facet fusion in addressing pseudoarthrosis-related symptoms and promoting spinal stability [5,8]. Moreover, the substantial proportion of patients undergoing fusion due to foraminal stenosis further emphasizes the efficacy of this surgical approach in addressing neural compression and associated radicular symptoms [5,9-11]. Regarding to foraminal stenosis, Lenzi et al. [12] published in 2017 a prospective randomized controlled study reporting significant improvement with interfacet spacers versus conservative treatment. The presence of failed prosthetic implants as a prevalent indication underscores the importance of surgical revision and highlights the challenges associated with prosthetic implant durability. Additionally, the identification of adjacent segment pathology as an indication for fusion in a subset of patients underscores the multifactorial nature of cervical spine pathology and the need for comprehensive surgical management strategies. Furthermore, the necessity for reinforcement of fusion at previously treated levels in a small percentage of cases highlights the complexities of managing recurrent or persistent symptoms following prior surgical intervention. In relation with adjacent segment Siemionow et al. [13] reported no more than expected rate of adjacent segment after posterior cervical interfacet fusion compared with other techniques. Overall, our findings reaffirm the diverse array of indications for posterior cervical facet fusion procedures and underscore the importance of individualized treatment approaches tailored to address specific pathologies and patient needs. Miscellaneous indication includes C1–2 stabilization which has been reported recently in the literature though no cases in our series [14,15].

The assessment of clinical and functional outcomes following posterior cervical facet fusion procedures using the DTRAX system yielded promising results, consistent with findings reported in the existing literature. Our study revealed a substantial reduction in both axial and radicular pain, as evidenced by significant improvements in mean VAS scores at various postoperative time points. This observed reduction in pain scores highlights the efficacy of posterior cervical facet fusion in alleviating symptomatic neck and radicular pain, thereby enhancing patient-reported outcomes and overall quality of life. These findings are congruent with previous studies reporting favourable pain relief outcomes following similar surgical interventions, underscoring the robustness of posterior cervical facet fusion as an effective treatment modality for cervical spine pathology. Specifically, regarding radicular pain, those studies have demonstrated that the DTRAX system effectively enlarges the foraminal dimensions, thereby reducing the pressure on the nerve roots. This indirect decompression method is beneficial as it minimizes the need for extensive bone removal or manipulation, reducing the risk of destabilizing the spine and promoting faster recovery. The increase in foraminal height (up to 20%) is achieved through a combination of distraction and fusion techniques, which realign the cervical vertebrae and maintain the increased space over the long term [10,16].

Furthermore, our analysis of functional outcomes using the NDI demonstrated significant improvements in functional status following DTRAX procedures. Patients exhibited a notable decrease in mean NDI scores postoperatively, indicative of enhanced functional capacity and reduced disability levels. This improvement was particularly evident in the early postoperative period, with a significant decrease in NDI scores observed at 7 days postoperatively, signifying rapid functional recovery following surgical intervention. Subsequent follow-up evaluations at 1, 6, and 12 months postoperatively revealed sustained enhancements in functional outcomes, further reinforcing the long-term benefits of posterior cervical facet fusion in improving patient functionality and overall well-being.

The observed trends in pain reduction and functional improvement align closely with findings reported in the literature, corroborating the favourable clinical outcomes associated with posterior cervical facet fusion procedures. Studies investigating similar surgical techniques have consistently reported significant reductions in pain scores and improvements in functional status postoperatively, supporting the efficacy and reliability of this treatment approach. Additionally, the statistically significant improvement in overall NDI scores further validates the clinical utility of posterior cervical facet fusion in addressing the functional impairment associated with cervical spine pathology.

Radiographic evaluation plays a crucial role in assessing the success of cervical fusion procedures, providing valuable insights into fusion rates and treatment outcomes. In our study, we utilized CT scans to evaluate the fusion status of posterior cervical facet fusion procedures using the DTRAX system. Our findings revealed favourable fusion outcomes, with a fusion rate of 88% observed at the 6-month follow-up, which further increased to 96% at the 12-month mark. Comparing these fusion rates with those reported in the literature for other cervical fusion systems underscores the efficacy of the DTRAX system in achieving satisfactory fusion outcomes. Voronov et al. [17] reported on the biomechanical evaluation of the DTRAX posterior cervical cage stabilization system, highlighting its potential for promoting fusion in cervical spine surgery. Similarly, Yazdanshenas et al. [18] conducted a retrospective evaluation of cervical fusion with the DTRAX cervical cage, further supporting its effectiveness in achieving fusion.

The fusion rates observed in our study are consistent with or exceed those reported for other cervical fusion systems in the literature. This suggests that the DTRAX system is associated with robust fusion outcomes, indicating its reliability and efficacy in promoting cervical fusion. The ability of the DTRAX system to achieve high fusion rates is particularly noteworthy, as successful fusion is essential for stabilizing the cervical spine, relieving symptoms, and preventing complications such as pseudoarthrosis.

Regarding complications, the occurrence of mispositioned interfacet spacers underscores importance of meticulous surgical technique and thorough intraoperative assessment to ensure optimal placement of devices such as the DTRAX system. While our study reported only 2 cases of mispositioned implants with only fusion rate consequence in one case, the insights provided by the literature shed light on potential complications associated with implant mispositioning. DTRAX system relies on precise placement within the cervical facet joints to achieve desired outcomes. The reported cases of mispositioned spacers and subsequent management strategies underline the need for vigilance and caution when implementing novel surgical techniques. Surgeons utilizing the DTRAX system should be mindful of patient anatomy, particularly the size of facet joints and lateral masses, which may increase the risk of mispositioning. Additionally, the limitations of intraoperative fluoroscopy in confirming implant placement highlight the potential utility of intraoperative CT imaging to verify the accuracy of device positioning. By acknowledging the challenges associated with mispositioning and adopting a proactive approach to intraoperative imaging and assessment, surgeons can mitigate the risks of complications and optimize patient outcomes when utilizing the DTRAX system for posterior cervical facet fusion [19].

Neurological complications associated with the utilization of the DTRAX system in posterior cervical facet fusion procedures are relatively infrequent but warrant consideration. While our study reported limited instances of neurological complications, including transient paraesthesia and foraminal bone stenosis necessitating anterior revision surgery, these events underscore the importance of meticulous surgical technique and vigilant postoperative monitoring. The occurrence of transient paraesthesia highlights the potential for nerve irritation or injury during the surgical procedure, emphasizing the need for careful attention to anatomical structures and nerve protection techniques [20]. Additionally, the need for anterior revision surgery in cases of foraminal bone stenosis underscores the importance of thorough preoperative assessment and intraoperative imaging to ensure optimal implant placement and prevent postoperative complications. While neurological complications with the DTRAX system are rare, their identification underscores the importance of comprehensive preoperative planning, meticulous surgical technique, and diligent postoperative management to minimize risks and optimize patient outcomes. Continued vigilance and ongoing research efforts are essential to further elucidate the incidence, risk factors, and management strategies for neurological complications associated with the DTRAX system in posterior cervical facet fusion procedures [3].

While DTRAX complications were limited in occurrence, their identification accentuates the need for comprehensive preoperative assessment, meticulous surgical technique, and vigilant postoperative monitoring to minimize risks and optimize patient outcomes.

Limitations of our study include its retrospective design, which inherently introduces the possibility of selection bias and confounding variables. The lack of a control group limits our ability to compare outcomes directly with alternative treatment modalities or surgical techniques. Additionally, the relatively small sample size may restrict the generalizability of our findings to broader patient populations. The short to midterm follow-up duration of 12 months may not capture long-term outcomes or potential late complications associated with posterior cervical facet fusion using the DTRAX system, although there are results in the literature that support a sustained response to treatment up to 2 years follow-up [16]. Regarding cervical alignment, an and based on the findings of McCormack and Dhawan [6] and Tan et al. [21], long-term outcomes following cervical spine surgery, including DTRAX procedures, generally show promising results in maintaining spinal alignment and preventing kyphotic changes. Tan et al. [21] reported that patients undergoing cervical fusion procedures showed minimal kyphotic progression over a long-term follow-up period, attributing this stability to effective surgical techniques and appropriate postoperative management. Similarly,McCormack and Dhawan [6] observed that patients who underwent minimally invasive cervical procedures, such as DTRAX, maintained satisfactory cervical alignment with a low incidence of kyphotic changes over several years.

While our study's 12-month follow-up demonstrates positive clinical short-term outcomes, and some pre and postoperative x-ray comparison in our series demonstrate no significant kyphotic change in cervical alignment (Figure 5), we recognize the need for extended follow-up to thoroughly evaluate long-term spinal alignment. Future studies will aim to include longer follow-up periods to provide a more comprehensive understanding of the long-term effects of DTRAX procedures on cervical alignment.

Figure 5.

Plain x-rays (preoperative [A] and postoperative [B]), demonstrating minimal kyphotic changes after the DTRAX procedure.

Furthermore, while efforts were made to meticulously document perioperative complications and adverse events, the retrospective nature of data collection may have led to underreporting or incomplete capture of such events.

Future prospective studies with larger sample sizes and longer follow-up periods are warranted to validate our findings and further elucidate the efficacy, safety, and durability of the DTRAX system in the management of cervical degenerative pathology.

Additionally, loss of cervical lordosis is a concern in spinal fusion procedures, including those utilizing the DTRAX system. While our study did not directly measure cervical spine angles, literature suggests that loss of lordosis can occur following posterior cervical fusion surgeries although not being relevant. Specifically, with DTRAX, a mean of 1.6 degrees by level was reported by Tan et al. [21] and a not statistically significant loss of lordosis by McCormack et al. [9].

CONCLUSION

Our retrospective analysis of 50 cases provides valuable insights into the utilization of the DTRAX system for posterior cervical facet fusion procedures. The study highlights the efficacy of the DTRAX system in achieving favourable clinical outcomes, including significant reductions in pain, improvements in functional status, and high fusion rates observed on radiographic evaluation. Despite limitations inherent to retrospective analyses, our findings contribute to the growing body of evidence supporting the utility of the DTRAX system as a minimally invasive and effective treatment option for cervical degenerative pathology. Continued research efforts and long-term follow-up studies are essential to further elucidate the role of the DTRAX system in optimizing patient outcomes and refining surgical techniques in the management of cervical spine disorders.

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