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ORIGINAL ARTICLE
Year : 2023 | Volume
: 14
| Issue : 1 | Page : 59-64
Arthrodesis versus dynamic neutralization: A short/mid- and long-term retrospective evaluation in degenerative disk disease treatment
Leonard Meco1, Simone Stefano Finzi2, Dalila Scoscina2, Silvia Amico2, Francesco Saverio Sirabella2, Marco Rotini2, Monia Martiniani1, Nicola Specchia2, Antonio Pompilio Gigante2
1 Clinic of Adult and Paediatric Orthopaedics, Azienda Ospedaliero-Universitaria, Ospedali Riuniti Di Ancona, Ancona, Italy
2 Department of Clinical and Molecular Sciences, Università Politecnica Delle Marche, Ancona, Italy
Correspondence Address:
Silvia Amico
Department of Clinical and Molecular Sciences, Università Politecnica Delle Marche, Via Tronto 10/a, Torrette Di Ancona 60020
Italy
Source of Support: None, Conflict of Interest: None
CheckDOI: 10.4103/jcvjs.jcvjs_159_22
Abstract
Study Design: This was a retrospective comparative study.
Objectives: The aim of this study was to perform a clinical and radiological retrospective evaluation of the most used techniques for the lumbar degenerative disk disease (DDD) treatment: arthrodesis versus dynamic neutralization (DN)-Dynesys dynamic stabilization system.
Methods: The study included 58 consecutive patients affected by lumbar DDD, 28 treated with rigid stabilization and 30 with DN at our department between 2003 and 2013. The clinical evaluation was performed through the Visual Analog Scale (VAS) and the Oswestry Disability Index (ODI). The radiographic evaluation was performed through standard and dynamic X-ray projections and magnetic resonance imaging.
Results: Both techniques determined a clinical improvement in the postoperative period compared to the preoperative one. There were no significant differences between the postoperative VAS of the two techniques. The DN group postoperative ODI percentage showed a significant improvement (P = 0.026) compared to the arthrodesis group. During the follow-up, no clinically significant differences were highlighted between the two techniques. At a long term follow up period, radiographic results showed, in both groups, a L3–L4 disk mean height reduction and an increase of segmental and lumbar lordosis without significant differences between the two techniques. During an average of 96-month follow-up period, 5 (18%) patients developed an adjacent segment disease in the arthrodesis group and 6 (20%) patients developed this syndrome in the DN group.
Conclusions: We are confident in recommending arthrodesis and DN as effective techniques for lumbar DDD treatment. Both techniques are potentially burdened, with similar frequency, by the development of long-term adjacent segment disease.
Keywords: Adjacent segment disease, arthrodesis, degenerative disk disease, dynamic neutralization
Introduction 
Lumbar degenerative disk disease (DDD) is the most common cause of low back pain and the main target of diagnostic procedures and surgical interventions. There are many options for conservative treatments: lifestyle modifications, rehabilitation/physical therapy, and drug assumption. On the other side, different surgical techniques have been developed with the intent to solve local instability and biomechanical alterations that cause pain and invalidity.
Arthrodesis is a procedure aiming to obtain the fusion of the degenerated segments, statically avoiding the biomechanical instability.[1],[2] However, some authors consider arthrodesis as a destructive procedure that subjects adjacent segments to an accelerated degenerative process.[3],[4] Dynamic neutralization (DN) aims to modify the biomechanical loads on the degenerated disks without abolishing the segmental mobility.[5] The fusion of the treated segments determines an overload on the adjacent ones, causing an adjacent segment disease, that in many cases requires a further surgical intervention.[6],[7],[8] The aim of this study is to perform a short/mid- and long-term retrospective clinical and radiological evaluation of the most used techniques for lumbar DDD treatment, arthrodesis versus DN, in order to highlight the long-term effectiveness guaranteed by both treatments and the incidence and characteristics of the adjacent segment disease.
Methods The study included 58 consecutive patients (30 males and 28 females) affected with lumbar DDD, treated with surgical intervention at our department, between 2003 and 2013.
Surgical intervention was indicated in case of a radicular pain and/or a chronic low back pain and/or a claudicatio spinalis resistant to conservative treatment for at least 6 months.
In order to obtain a homogeneous sample, only patients treated at L4–L5 level were included in the study. Patients submitted to L4–L5 arthrodesis because of neoplastic or inflammatory diseases, recent fractures, DDD as fracture consequence, childhood and adolescence deformity, or ontogenetic spondylolisthesis were excluded from the study.
Out of these 58 patients, 14 were affected by lumbar stenosis, 11 by DDD with degenerative spondylolisthesis, 1 by DDD with extruded hernia, and 32 by L4–L5 DDD.
These patients were then divided into two different groups as follows:
Group A (arthrodesis): 28 patients treated with rigid stabilizationGroup B (DN): 30 patients treated with Dynesys dynamic stabilization system.For each patient, both clinical and radiological evaluation was performed. Patients were evaluated in the preoperative and postoperative periods and in a short/mid- and long-term follow-up period.
Clinical evaluation was performed through the Visual Analog Scale (VAS) and the Oswestry Disability Index (ODI).
In order to better evaluate short/mid- and long-term results, Group A (arthrodesis) and Group B (DN) were divided into subgroups according to the duration of the follow-up.
Group A follow-up lasted between 36 and 156 months, and was divided into:
Subgroup A1: Short/mid follow-up period between 36 and 102 months (56.57 ± 20.9 months)Subgroup A2: Long follow-up period between 102 and 156 months (128.57 ± 14.6 months).Group B follow-up lasted between 36 and 156 months, and was divided in:
Subgroup B1: Short/mid follow-up period between 36 and 126 months (88.57 ± 24.4 months)Subgroup B2: Long follow-up period between 126 and 156 months (140.00 ± 4.7 months).Radiographic evaluation included main and secondary radiographic criteria in standard and dynamic X-ray projections.
The main radiographic criteria analyzed were as follows: mean height of the L3–L4 disk, L3–segmental lordosis, and T12-L5 lordosis modifications >10°–15°. The secondary radiographic criteria were as follows: instability signs (presence of anterior or posterior 3–4 mm translation of the vertebrae above and under the treated level), presence of osteophytes and sclerosis of the vertebral body end-plates, and degenerative scoliosis.
Clinical and radiographic results were analyzed through the Student's t-test to evaluate the differences between Group A and Group B. P < 0.05 was assumed as statistically significant.
Results Group A included 28 patients (11 males + 17 females, mean age: 52.6 years). These patients had the following diagnosis: 11 – lumbar stenosis, 9 – DDD with degenerative spondylolisthesis, 7 – DDD, and 1 – DDD with extruded hernia. L4–L5 posterolateral arthrodesis (PLA) was performed in 19 patients (6 – PLA + uni/bilateral foraminotomy and 13 – PLA + laminectomy), L4–L5 circumferential arthrodesis + laminectomy in 8 patients, and posterior arthrodesis by translaminar screw fixation + unilateral foraminotomy in 1 patient.
Group B included 30 patients (19 males + 11 females, mean age: 50.4 years). These patients had the following diagnosis: 26 – DDD, 3 – monosegmental lumbar stenosis, and 1 – DDD with L4–L5 degenerative spondylolisthesis. Wiltse paraspinal approach (WPA) was performed in 20 patients, classical approach (CA) in 9 patients (6 – CA + partial laminectomy and 3 – CA + unilateral foraminotomy), and combined approach (right WPA + CA with related decompression) in 1 patient.
Clinical outcomes
Group A and Group B showed a significant improvement (P < 0.01) of both the average VAS and ODI percentage between the postoperative and follow-up periods compared to the preoperative period. The details are shown in [Table 1] and [Table 2].
Table 1: Clinical outcomes: Visual Analog Scale comparison within Group A in the pre/post- and prefollow-up periods
Table 2: Clinical Outcomes: Oswestry Disability Index percentage comparison within Group A in the pre/post and pre/follow-up periodsComparing Group A and Group B, there were no significant differences between the average postoperative VAS.
The average Group B postoperative ODI percentage showed a significant improvement (P = 0.026) compared to Group A. There were no significant differences in the short/mid- and long-term follow-up periods comparing the VAS and ODI average values between the two different types of interventions. The data are recapped in [Table 3].
Table 3: Clinical outcomes: Visual Analog Scale and Oswestry Disability Index percentage comparison between Group A and Group BRadiographic outcomes
The [Table 4] shows, for each group, the values of the mean height of the L3–L4 disk, L3–L4 segmental lordosis and T12 L5 lordosis in the preoperative and follow up (96 months) periods.
After 96 months, a L3–L4 disk mean height reduction and an increase of segmental and lumbar lordosis were observed in both the groups compared to the preoperative.
No significant differences were found comparing the radiographic outcomes of the two groups after a 96-month follow-up period.
Adjacent segment disease
Eighty-two percent of Group A population had an overall improvement of clinical outcomes.
In five patients (18%), a clinical worsening and L3–L4 DDD radiological signs were observed during the follow-up. These five patients were submitted to adjacent segment disease surgical revision.
In four of these, we performed a system revision by extending it to the L3–L4 level associated with laminotomy. In one patient, the system was removed and a L3–L4 foraminotomy was performed.
Eighty percent of Group B population had an overall improvement of clinical outcomes.
In six patients (20%), a clinical worsening and L3–L4 DDD radiological signs were observed during the follow-up. In five of these, an adjacent segment disease diagnosis was made and they were submitted to the following treatment:
Surgical revision by extending the Dynesys system to the level above L3–L4 (2)Dynesys system removal and DN at the level above (1)Dynesys system removal and L3–L5 PLA with laminectomy (2).Complications
In 4 cases (6.90%), complications occurred:
Two perioperative infections, treated with early surgical wound review and antibiotic therapyOne 5-year-late system infection, treated with antibiotic therapyOne screw mobilization observed 8 years after the intervention through a radiographic control executed after the appearance of lumbar pain. Discussion Many authors consider arthrodesis as a “destructive” procedure because it aims at the facet joint fusion, causing a loss of physiological mobility of the lumbar spine and the acceleration of the nearby segment degenerative process. These reasons, overtime, encouraged the development of dynamic systems to avoid rigid arthrodesis. Dynamic systems preserve mobile segments, avoiding their fusion.[9] A long-term follow-up study showed good clinical and radiographic results in patients <60 years of age with mild-to-moderate lumbar DDD treated with Dynesys stabilization for lumbar stenosis with or without spondylolisthesis.[10]
In literature, available data concerning the clinical outcome for patients undergoing arthrodesis intervention or DN for lumbar DDD show that both treatments can accelerate the degeneration of the adjacent disks. Park et al. in 2004 drafted a review based on biomechanical studies of 22 lumbar DDDs treated by arthrodesis and highlighted how segment fusion increases physical stress on adjacent segments.[8] The increased intradiscal pressure, the facet joint stress, and the segmental hypermobility accelerate the degenerative phenomena of the adjacent disk. The incidence of radiographic signs of DDD reaches 100%. On the other hand, the incidence of clinical expression of the adjacent segment disease ranges between 5.2% and 28.5%. The risk factors more frequently associated with adjacent segment disease are the following: age >55 years, female, osteoporosis, coronal and sagittal plane deformity, and size of the arthrodesis area.
Okuda et al. in 2004 evaluated risk factors associated with the development of adjacent segment disease in L4–L5 DDD patients treated through arthrodesis (posterior lumbar intersomatic fusion). They concluded that there was no correlation between radiologic degeneration of cranial adjacent segment and clinical results. Lumbar DDD postoperative risk factors are similar to the preoperative ones, following the natural aging. The higher physical stress on facet joint seems to accelerate the proximal adjacent disk aging process itself.[11]
Kumar et al., in a retrospective study of 2001, compared two patient groups: the first one underwent arthrodesis and the other one DN with a 5-year long follow-up. They affirmed that the incidence of degeneration of the cranial segments adjacent to the treated area, evaluated with radiologic parameters, was doubled in patients subjected to arthrodesis treatment compared to DN one. However, there were no statistically significant differences comparing the clinical and functional results of both the groups.[12]
Virk et al. (2014) compared clinical and radiological results between arthrodesis and DN. They concluded that DN long-term outcomes were better, but, for more reliable results, a longer follow-up period was needed.[13]
Schwarzenbach et al. and Welch et al. reported comparable clinical outcomes for patients subjected to the two different techniques. They highlighted the Dynesys system efficacy in ensuring stability to the treated pathological level, preserving its mobility. However, they concluded that a long-term follow-up was recommended for more reliable data.[14],[15]
Beastall et al. evaluated magnetic resonance imaging of lumbar DDD patients treated with Dynesys system during early and mid-term follow-up periods. They highlighted that in 93.4% of cases, L4–L5 disk presented no signs of degeneration progress and that the system did not modify facet joint structure of the treated segment and of the adjacent disk.[16]
Schaeren et al. in 2008 conducted a study on lumbar DDD patients treated with DN. In a short-term follow-up period, clinical results were good, but after 4 years, there was a worsening of the adjacent disk degeneration in 47% of cases. Therefore, on a long-term basis, clinical results were similar to arthrodesis.[17]
The aim of this study is the comparison between short/mid- and long-term clinical results of arthrodesis and DN. In our experience, both techniques determine a clinical improvement in the postoperative period compared to the preoperative. Regarding the postoperative VAS results, no significant differences were found between these two techniques, while in the DN group, ODI's postoperative percentage results showed a significant improvement compared to the arthrodesis group. This difference could be explained by patients' intrinsic factors such as age, weight, comorbidities, and factors related to the different techniques adopted, such as surgical access and approach.
At a short/mid- and long-term follow-up, no statistically significant differences were highlighted concerning clinical results between the two techniques.
At a long term follow up period, radiographic results showed, in both groups, a L3–L4 disk mean height reduction and an increase of segmental and lumbar lordosis without significant differences between the two techniques.
In this study, the percentage of adjacent segment disease cases was similar in both the groups (18% in the arthrodesis group vs. 20% in the DN group). Pham et al. reviewed the literature and asserted that the Dynesys dynamic stabilization system appeared to have a fairly similar complication rate profile compared with lumbar fusion, and was associated with a slightly lower incidence of adjacent segment disease.[18]
Conclusions Based on recent scientific literature and our retrospective study conducted, we are confident in recommending arthrodesis and DN as effective techniques for lumbar DDD treatment.[19],[20]
Both techniques are potentially burdened, with similar frequency, by the development of long-term adjacent segment disease.
Acknowledgment
The authors would like to thank Health Physics Department, Ospedali Riuniti di Ancona, for the support.
Financial support and sponsorship
Nil.
Conflicts of interest
The authors certify that they have NO affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers' bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or non-financial interest (such as personal or professional relationships, affiliations, knowledge, or beliefs) in the subject matter or materials discussed in this manuscript.
References 
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