Superiority of Lumbar Fusion Surgery with ISOBAR Devices over Posterior Lumbar Interbody Fusion Surgery in Patients with Lumbar Degenerative Diseases: An Invited Brief Commentary

This article is referred to by:

Effects of Lumbar Fusion Surgery with ISOBAR Devices Versus Posterior Lumbar Interbody Fusion Surgery on Pain and Disability in Patients with Lumbar Degenerative Diseases: A Meta-Analysis

In Effects of lumbar fusion surgery with ISOBAR devices versus posterior lumbar interbody fusion (PLIF) surgery on pain and disability in patients with lumbar degenerative diseases (LDD): a meta-analysis, the authors and investigators aim to evaluate the overall efficacy of lumbar fusion surgery with ISOBAR devices versus PLIF surgery for alleviating LDD-associated pain and disability [1]. Su et al. [1] have taken a worthwhile first step toward a better understanding of this important clinical issue. This meta-analysis is a well-written and consolidated systemic review which is enlightening, but beyond the strengths and weaknesses of this study, we would like to make some comments.

Lumbar fusion fixation is the main surgical method for the treatment of LDD. The results of this systematic review and meta-analysis suggest that lumbar fusion surgery with ISOBAR devices significantly alleviates general pain, lower back pain, and disability in patients with LDD [1]. Moreover, lumbar fusion surgery with ISOBAR devices was associated with lower postoperative disability than PLIF [1]. This study adds comprehensive information about the efficacy of ISOBAR devices compared to PLIF for LDD. Their findings are important as they provide a better cure for back pain without predisposing patients to future spinal problems. Meanwhile, however, the fact that there are many studies in the literature which show that posterolateral fusion (PLF) provides better clinical outcomes and more improvement in low back pain than PLIF [2, 3] raises this question that if according to Su et al. [1], ISOBAR device use is superior to standard approaches such as PLIF, then we can take a step forward and hypothesize that ISOBAR device may also be more effective than PLF, but this should be investigated. Regarding different findings of various studies, we cannot reach a consensus on the superiority of ISOBAR devices over PLF. Consequently, more controlled trials or similar systematic review and meta-analyses are needed to compare the benefits of ISOBAR devices with that of PLF in patients with LDD. The overall findings of such studies and the Su et al.’s [1] study will increase our knowledge about the benefits of ISOBAR device use for patient and clinician decision-making for spinal surgery.

One of the major issues after lumbar spinal fusion is the development of adjacent segment disease (ASD), resulting in clinical symptoms and detectable imaging study abnormalities [4]. Degeneration that develops at mobile segments above or below a fused spinal segment is known as ASD [2]. The increase of adjacent segment compensatory activity after rigid internal fixation is one of the most important causes of adjacent segment degeneration [5]. Adjacent segment degeneration is not always associated with severe complaints and only a part of these patients required revision surgery [6]. Lee et al. [7] studied a consecutive series of 490 patients who had undergone lumbar spinal fusion of three or fewer segments to treat LDD and they showed that patients who undergo PLIF were suspected to experience a higher incidence of ASD. This disadvantage of the fixed rigid internal fixation system has led to the concept of dynamic lumbar fixation. In 1997, ISOBAR TTL dynamic rod stabilization was developed for application in spinal fusion surgery to prevent ASD-related complications. ISOBAR device is a type of semi-rigid lumbar, posterior approach, dynamic, and screw rod fixation system which allows some mobility of the fixation segments, maintains height of intervertebral space, reduces the bearing load of the discs and facet joints, and further prevents or slows down the degeneration of the fixation segment [8]. Jahng et al. [9] indicated that the ISOBAR TTL system can effectively maintain postoperative lumbar activity and reduce stress shielding, which could theoretically slow the dynamic fixed segment degeneration. In 2015, the findings of a study conducted by Yang et al. [10] on the comparison of clinical and radiographic results between ISOBAR posterior dynamic stabilization and PLIF for LDD showed that although ISOBAR posterior dynamic stabilization is an effective and safe treatment for LDD, that there is insufficient evidence to indicate that the ISOBAR posterior dynamic stabilization can avoid ASD [10]. However, we agree with Su et al. [1] on this point that ISOBAR is a more valid treatment option in the management of LDD than PLIF because several studies have shown the ISOBAR to have good short-term outcomes in terms of fusion and decreasing the incidence of ASD [5, 11].

Ekman et al. [12] found significantly more complications in patients operated on with PLIF. The PLIF technique is more invasive, technically more demanding, and results in a longer operating time and a larger blood loss, factors all increasing the risk of complication [13]. Many studies have reported that some complications associated with the PLIF procedure are permanent neurological deficit, cerebrospinal fluid leakage, radicular pain, and deep wound infection [2, 13]. In addition to sagittal balance, clinical outcomes of instrumented PLIF in patients with LDDs may be influenced by a variety of pathophysiologic factors [14], including residual compression of the neural tissues, recurrence of spinal canal stenosis, irreversible changes to the nerve root, or cauda equine. We suggest that in another meta-analysis, the complications of the ISOBAR devices and PLIF and pathophysiologic factors can be studied.

One of the strengths of this study is that Table 1 shows both the characteristics of included studies for the evaluations of lumbar fusion surgery with ISOBAR devices and the comparisons between fusion surgery with ISOBAR devices (intervention) and PLIF (control). However, a weakness of this meta-analysis is that the aim of this study [1] seems unclear and we cannot recognize if the authors aimed to validate and verify the efficacy of ISOBAR devices in lumbar fusion surgeries in seven studies by making a comparison of (a) pre- and postoperative VAS pain scores, (b) pre- and postoperative lower back pain JOABPEQ scores, and (c) pre- and postoperative ODI scores, or they aimed to evaluate to compare the efficacy of lumbar fusion surgery with ISOBAR devices versus PLIF surgery for alleviating LDD-associated pain and disability in 11 studies and to determine whether ISOBAR device use is superior to PLIF? Consequently, we suggest that further future studies with inclusion of more studies can be conducted to separate these two aims and reach a consensus on the optimal technique for alleviating pain and disability in patients with LDD.

We think that in the parts of this study where the preoperative and postoperative data have been reported, it is better not to use standard mean difference (SMD) because according to the statistical definition of the SMD, it is used to evaluate the difference of mean between two independent groups. In future studies, we suggest that the effect size of each study and the mean and standard deviation of each group can be reported. Moreover, it seems that in this study [1], reporting the data of the Egger’s regression test was enough and the use of Funnel plots just added additional information.

At the end of the day, the major problem with the ISOBAR devices is its service life. Because the screws and the rods used for the dynamic stabilization bear long-lasting stress, there is a risk of internal fixation breakage over time. Meanwhile, the system’s reliability for maintaining spinal height, the bone resorption around the screw, the failure of the amphiarthrodial joint, and the collision between screws, rods, and the facet joints are the hidden risks [15]. This issue can be considered in future studies.

DECLARATION OF INTEREST

There is no conflict of interest to be declared regarding the manuscript. Each author certifies that he or she has no commercial associations (e.g., consultancies, stock ownership, equity interest, patent/licensing arrangements, etc.) that might pose a conflict of interest in connection with the submitted article.