Lumbar Disc Prosthesis Research Articles

Structural modification and biomechanical analysis of lumbar disc prosthesis: A finite element study

BackgroundMost ball-in-socket artificial lumbar disc implanted in the spine result in increased hypermobility of the operative level and overloading of the facet joint. MethodsA finite element model was established and validated for the lumbar spine (L1-L5). The structure of the Mobidisc prosthesis was modified, resulting in the development of two new intervertebral disc prostheses, Movcore and Mcopro. The prostheses were implanted into the L3/L4 level to simulate total disc replacement, and the biomechanical properties of the lumbar spine model were analyzed after the operation. FindingsFollowing the implantation of the prostheses, the mobility of operative level, peak stress of lumbar spine models, and peak stress of facet joint increased. The performance of mobility was found to be more similar between Movcore and Mobidisc. The mobility and facet joint peak stress of the Mcopro model decreased progressively with an increase in the Young's modulus of the artificial annulus during flexion, extension, and lateral bending. Among all the models, the Mcopro50 model had the mobility closest to the intact model. It showed a 3% decrease in flexion, equal range of motion in extension, a 9% increase in left lateral bending, a 7% increase in right lateral bending, and a 3% decrease in axial rotation. InterpretationThe feasibility of the new intervertebral disc prostheses, Movcore and Mcopro, has been established. The Mcopro prosthesis, which features an artificial annular structure, offers significant advantages in terms of reduced mobility of the operative level and peak stress of facet joint.

Cadaveric biomechanical studies of ADDISC total lumbar disc prosthesis

BackgroundMost total disc replacements provide excessive mobility and not reproduce spinal kinematics, inducing zygapophyseal joint arthritic changes and chronic back pain. In cadaveric lumbosacral spines, we studied if a new lumbar disc prosthesis kinematics mimics the intact intervertebral disc. MethodsIn eight cold preserved cadaveric lumbosacral spines, we registered the movement ranges in flexion, extension, right and left lateral bending, and rotation in the intact status, post-discectomy, and after our prosthesis implantation, comparing them for each specimen. FindingsComparing the intact lumbosacral spine with the L4-L5 prosthesis implanted specimens, we saw statistically significant differences in lateral bending and right rotation but not in the full range of rotation. Analyzing segments, we also noticed statistically significant differences at L4-L5 in flexion-extension and rotation. On the other hand, the L4-L5 discectomy, compared to the baseline spine condition, showed a statistically significant mobility increase in flexion, extension, lateral bending, and axial rotation, with an abnormal instantaneous center of rotation, which destabilizes the segment partly due to anterior annulus surgical removal. Disc prosthesis implantation reversed these changes in instantaneous center of rotation, but the prosthesis failed to restore the initial range of motion due to the destabilization of the ligaments in the operated disc. InterpretationThe ADDISC total disc replacement reproduces the intact disc kinematics and Instantaneous Center of Rotation, but the prosthesis fails to restore the initial range of motion due to ligament destabilization. More studies will be necessary to define a technique that restores the damaged ligaments when implanting the prosthesis.

Biomechanical consequences of the intervertebral disc centre of rotation kinematics during lateral bending and axial rotation

The location of the instantaneous centre of rotation (ICR) of a lumbar unit has a considerable clinical importance as a spinal health estimator. Consequently, many studies have been conducted to measure or estimate the ICR during rotations in the three anatomical planes; however the results reported are widely scattered. Even if some inter-subjects variability is to be expected, such inconsistencies are likely explained by the differences in methods and experiments. Therefore, in this paper we seek to model three behaviours of the ICR during lateral bending and axial rotation based on results published in the literature. In order to assess the metabolic and mechanical sensibility to the assumption made on the ICR kinematics, we used a previously validated three dimensional non-linear poroelastic model of a porcine intervertebral disc to simulate physiological lateral and axial rotations. The impact of the geometry was also briefly investigated by considering a 11^circ wedge angle. From our simulations, it appears that the hypothesis made on the ICR location does not significantly affect the critical nutrients concentrations but gives disparate predictions of the intradiscal pressure at the centre of the disc (variation up to 0.7 MPa) and of the displacement fields (variation up to 0.4 mm). On the contrary, the wedge angle does not influence the estimated intradiscal pressure but leads to minimal oxygen concentration decreased up to 33% and increased maximal lactate concentration up to 13%. While we can not settle on which definition of the ICR is more accurate, this work suggests that patient-specific modeling of the ICR is required and brings new insights that can be useful for the development of new tools or the design of surgical material such as total lumbar disc prostheses.

ADDISC lumbar disc prosthesis: Analytical and FEA testing of novel implants

The intact intervertebral disc is a six-freedom degree elastic deformation structure with shock absorption. “Ball-and-socket” TDR do not reproduce these properties inducing zygapophyseal joint overload. Elastomeric TDRs reproduce better normal disc kinematics, but repeated core deformation causes its degeneration. We aimed to create a new TDR (ADDISC) reproducing healthy disc features. We designed TDR, analyzed (Finite Element Analysis), and measured every 500,000 cycles for 10 million cycles of the flexion-extension, lateral bending, and axial rotation cyclic compression bench-testing. In the inlay case, we weighted it and measured its deformation.ADDISC has two semi-spherical articular surfaces, one rotation centre for flexion, another for extension, the third for lateral bending, and a polycarbonate urethane inlay providing shock absorption. The first contact is between PCU and metal surfaces. There is no metal-metal contact up to 2000 N, and CoCr28Mo6 absorbs the load. After 10 million cycles at 1.2–2.0 kN loads, wear 140.96 mg (35.50 mm3), but no implant failures. Our TDR has a physiological motion range due to its articular surfaces' shape and the PCU inlay bumpers, minimizing the facet joint overload. ADDISC mimics healthy disc biomechanics and Instantaneous Rotation Center, absorbs shock, reduces wear, and has excellent long-term endurance.

Study on anatomical parameters of adult lumbar intervertebral disc and endplate based on CT

To provide basic data for clinical application and individualized design of lumbar disc prostheses by measuring the anatomical parameters of lumbar intervertebral discs and endplates in healthy adults with CT three-dimensional reconstruction technology. A retrospective analysis was performed on 200 males and 200 females with normal lumbar spine who were admitted to the imaging center or outpatient department of the Second Affiliated Hospital of Xinjiang Medical University from September 2019 to December 2020. The age ranged from 20 to 60 years old, with an average of (40.61±11.22) years old. The measurement segment was L1-S1 intervertebral disc, and the measurement indicators included the axial anteroposterior diameter and transverse diameter of the intervertebral disc, sagittal anterior, middle and posterior height, coronal left and right height, intervertebral space angle, and transverse and anteroposterior diameters of the upper and lower endplates of each vertebral body. ①In terms of gender, the anatomical parameters of L1-S1 disc axial diameter, transverse diameter, sagittal anterior, middle and posterior height, left and right coronal height and intervertebral space angle were all higher in males than in females(P<0.05), and the anatomical parameters of upper and lower endplates of L1-S1 vertebral body were higher in males than in females(P<0.001). ②In comparison of sagittal height of anterior, middle and posterior intervertebral discs, the sagittal height of L1-L5 intervertebral discs was middle-high > anterior-high > posterior-high(P<0.001), while that of L5S1 intervertebral disc was anterior-high > middle-high > posterior-high (P<0.001). ③In the comparison of left and right coronal height, there was no statistical significance in the left and right coronal height of L1-S1 disc between male and female(P>0.05). ④The L1-S1 intervertebral spaces angle between male and female increased with the increase of vertebral body segments. ⑤The anterior and posterior diameters and transverse diameters of upper and lower of L1-S1 vertebral bodies endplates were height in males than in females(P<0.001). The results suggest that gender differences should be considered in the design of adult lumbar disc prostheses. The anatomical parameters of the lumbar intervertebral disc varied with the increase of the vertebral body sequence, suggesting that different anatomical parameters of the intervertebral disc should be considered in the design of the artificial intervertebral disc, and the changes in the height of the sagittal position suggest that the design of the intervertebral disc should be wedge-shaped.

Segmental Lordosis Gain Is a Prognostic Radiological Factor of Good Functional Outcome After the Implantation of a Single-Level Prosthesis or a Hybrid Construct for Lumbar Disc Degeneration

To identify radiological factors and functional outcomes associated with good results after implantation of a single lumbar disc prosthesis or a hybrid construct (anterior lumbar interbody fusion and lumbar disc prosthesis) in the setting of painful degenerative lumbar discopathy. This single-center, retrospective 10-year study included 92 patients ˃18 years old with chronic low back pain evolving for at least 1 year. The patients had degenerative disc disease and had failed conservative treatment and underwent lumbar arthroplasty. Radiographic and clinical outcomes were assessed preoperatively and 1 year after surgery. Functional evaluation was based on the Oswestry Disability Index (ODI) and a numerical rating scale. Radiological analysis was based on lumbar x-rays and magnetic resonance imaging parameters. Patients were assigned to 2 groups according to the reduction in ODI score (>15 points or <15 points), and statistical analysis was done in both groups to find predictive radiological factors for a satisfactory functional outcome. Clinically, 60 patients (65.2%) had a satisfactory functional result and 32 patients (34.8%) had a poor outcome according to ODI score. Radiographically, gain in segmental lordosis was statistically associated with good functional outcomes (8.9° for ODI decrease >15 vs. 3.2° for ODI decrease <15). This study determined that gain in segmental lordosis is associated with a satisfactory functional outcome after a single-level lumbar disc prosthesis or a hybrid construct. Our study demonstrates that segmental lordosis gain may represent a significative useful positive predictor factor of patient outcome.

Morphologic analysis of Chinese lumbar endplate by three-dimensional computed tomography reconstructions for helping design lumbar disc prosthesis.

Lumbar disc prostheses have been used increasingly in recent years. The successful design of lumbar disc prostheses depends on accurate morphometric parameters. However, the morphologic dimensions of lumbar endplate area have not been investigated in Chinese population.A total of 1800 lumbar endplates were retrospectively accessed in 150 Chinese adults. Eighteen parameters of each lumbar segment were measured by three-dimensional computed tomography reconstructions from T12/L1 to L5/S1. These obtained parameters were compared between genders, bilateral sides, vertebral segments, and different populations.Endplate length and width increased in general, and there was a significant decrease for length/width ratio from T12 to S1 (P = .03). The average concavity depth of the lower lumbar endplate (2.09 ± 0.93 mm) was usually larger than that of the upper lumbar endplate (1.61 ± 0.74 mm) (P = .02). The percentage of the most concave point of the upper and lower lumbar endplate was 50.01 ± 10.76% and 56.41 ± 9.93%, respectively. Anterior, medium, or posterior intervertebral endplate height was severally 10.01 ± 1.98 mm, 10.46 ± 2.03 mm, and 6.41 ± 1.74 mm, and increased among vertebral segments (P = .01).The intervertebral endplate angle significantly increased from T12-L1 to L5-S1 (P = .01). Parameters displayed significant difference between genders. The morphometric parameters of different populations also showed differences.In conclusion, there is a morphologic discrepancy in dimensions of lumbar endplate regarding genders, vertebral segments, and different populations. It is essential to design the lumbar disc prosthesis suited for Chinese patients specially, for which the morphometric parameters in our study can be utilized.

ICR in human cadaveric specimens: An essential parameter to consider in a new lumbar disc prosthesis design

Study designBiomechanical study in cadaveric specimens.BackgroundThe commercially available lumbar disc prostheses do not reproduce the intact disc's Instantaneous centre of Rotation (ICR), thus inducing an overload on adjacent anatomical structures, promoting secondary degeneration.AimTo examine biomechanical testing of cadaveric lumbar spine specimens in order to evaluate and define the ICR of intact lumbar discs.Material and MethodsTwelve cold preserved fresh human cadaveric lumbosacral spine specimens were subjected to computerized tomography (CT), magnetic resonance imaging (MRI) and biomechanical testing. Kinematic studies were performed to analyse range of movements in order to determine ICR.ResultsFlexoextension and lateral bending tests showed a positive linear correlation between the angle rotated and the displacement of the ICR in different axes.DiscussionICR has not been taken into account in any of the available literature regarding lumbar disc prosthesis. Considering our results, neither the actual ball-and-socket nor the withdrawn elastomeric nucleus models fit the biomechanics of the lumbar spine, which could at least in part explain the failure rates of the implants in terms of postoperative failed back syndrome (low back pain). It is reasonable to consider then that an implant should also adapt the equations of the movement of the intact ICR of the joint to the post-surgical ICR.ConclusionsThis is the first cadaveric study on the ICR of the human lumbar spine. We have shown that it is feasible to calculate and consider this parameter in order to design future prosthesis with improved clinical and biomechanical characteristics.

A review on the current state of ball-on-socket type artificial lumbar disc prosthesis

Total lumbar disc replacement is an alternative to interbody fusion for the effective treatment of symptomatic degenerative disc disease. This paper reviewed the history of ball-on-socket type artificial lumbar disc (ALD) prosthesis, which is a typical ALD prosthesis and summarized the ALD prosthesis research progress, according to different materials such as metal-on-metal, metal-on-polymer, and polymer-on-polymer prosthesis. The structural design factors of ball-on-socket type ALD prosthesis were analyzed and its prospect of development was also presented. The purpose of this paper is to provide a theoretical reference for the design of the ball-on-socket ALD prosthesis by reviewing the current state of ball-on-socket type ALD prosthesis.

Facet arthropathy evaluation: CT or MRI?

To assess the reliability of lumbar facet arthropathy evaluation with computed tomography (CT) or magnetic resonance imaging (MRI) in patients with and without lumbar disc prosthesis and to estimate the reliability for individual CT and MRI findings indicating facet arthropathy. Metal-artifact reducing CT and MRI protocols were performed at follow-up of 114 chronic back pain patients treated with (n = 66) or without (n = 48) lumbar disc prosthesis. Three experienced radiologists independently rated facet joint space narrowing, osteophyte/hypertrophy, erosions, subchondral cysts, and total grade facet arthropathy at each of the three lower lumbar levels on both CT and MRI, using Weishaupt et al's rating system. CT and MRI examinations were randomly mixed and rated independently. Findings were dichotomized before analysis. Overall kappa and (due to low prevalence) prevalence- and bias-adjusted kappa were calculated to assess interobserver agreement. Interobserver agreement on total grade facet arthropathy was moderate at all levels with CT (kappa 0.47-0.48) and poor to fair with MRI (kappa 0.20-0.32). Mean prevalence- and bias-adjusted kappa was lower for osteophyte/hypertrophy versus other individual findings (CT 0.58 versus 0.79-0.86, MRI 0.35 versus 0.81-0.90), higher with CT versus MRI when rating osteophyte/hypertrophy (0.58 versus 0.35) and total grade facet arthropathy (0.54 versus 0.31), and generally similar at levels with versus levels without disc prosthesis. Interobserver agreement on facet arthropathy was moderate with CT and better with CT than with MRI. Disc prosthesis did not influence agreement. A more reliable grading of facet arthropathy requires a more consistent evaluation of osteophytes/hypertrophy. • In this study, interobserver agreement on facet arthropathy (FA) severity-based on facet joint space narrowing, osteophyte/hypertrophy, erosions, and subchondral cysts-was better with CT versus MRI. • Metal-artifact reducing CT and MRI protocols helped to improve visibility and maintain agreement when evaluating severity of FA at levels with metallic disc prosthesis. • Agreement was poorer for severity of osteophytes/hypertrophy than for the other evaluated FA findings; improved agreement on total grade FA evaluated with CT or MRI thus requires more consistent grading of osteophytes/hypertrophy between different radiologists.

Abandoned techniques in spine surgery.

In spine surgery, certain surgical techniques and devices are currently in marked decline or have been completely abandoned. Although used in thousands of patients, such treatments failed to demonstrate durable and sound effectiveness, and sometimes associate inacceptable morbidity. Chemopapain injections, percutaneous discectomy, laser discectomy or antiadhesion gels are examples of abandoned therapies. Some other techniques are in frank decline like implantation of interspinous devices or lumbar disc prosthesis. In general, a technique is abandoned due to inefficacy, excessive associated morbidity, substituted by another more efficacious and less aggressive technique, end of commercialization, or usage prohibition. In the last decades, a great commercial pressure plus an increasing social demand have managed to convince many spine surgeons to indicate treatments not sufficiently supported by scientific evidence nor consolidated over time, many of which are eventually abandoned.

Finite element analysis of effects of movable artificial lumbar vertebra implantation on stress of adjacent intervertebral discs

Objective To compare the effects of movable artificial lumbar vertebra implantation and traditional vertebral excision and fusion on the stress of adjacent intervertebral discs, so as to provide reference for the biomechanical safety of new prosthesis implantation. Methods The total lumbar vertebra CT scan data of a healthy adult were imported into the computer-aided software Mimics 16.0 for three dimensional reconstruction. The reconstructed three dimensional model was smoothed using computer-aided software Geomagic Studio 12.0. Subsequently, meshing, parameter setting and ligaments reconstructing were completed using computer-aided software Hypermesh 13.0 and Solidworks 2013, successfully constructing the finite element model of lumbar vertebral physiology group. On the basis of the finite element model of physiological group, three vertebral bodies and two intervertebral spaces were fused and fixed, and a simplified finite element model of fusion group was constructed. The partitioned prosthesis model was inserted into the established finite element model of physiological group, replacing the L 3 vertebral body and the adjacent two intervertebral discs in the model, constructing the finite element model of non fusion group. Three finite element models were imported into computer-aided software Abaqus/Explict and loaded under six motion modes including anteflexion, dorsiflexion, left and right rotation, and left and right bending. The stress changes of adjacent intervertebral discs were calculated. Results The maximum Mises stress of the adjacent intervertebral disc in the direction of forward flexure, dorsal extension, left and right rotation and left and right lateral bending of the three finite element models was located at the site of loading and increased with the increase of loading. Under the maximum loading, the Mises stress of adjacent intervertebral discs in the above directions in the fusion group (L1-2 respectively were 0.79, 0.96, 1.26, 1.92, 1.34, 1.57 MPa while L4-5 respectively were 0.52, 1.13, 1.50, 1.74, 0.94, 0.87 MPa) was significantly higher than that in the physiological group (L1-2 respectively were 0.42, 0.53, 0.57, 0.66, 0.64, 0.72 MPa while L4-5 respectively were 0.23, 0.29, 0.68, 0.63, 0.37, 0.34 MPa). The Mises stress of adjacent intervertebral disc in the non-fusion group (L1-2 respectively were 0.38, 0.57, 0.75, 1.02, 0.87, 0.90 MPa while L4-5 respectively were 0.18, 0.26, 0.81, 0.98, 0.30, 0.27 MPa) was similar to that in the physiological group, although there was some difference. Conclusion Movable artificial lumbar disc prosthesis implantation can better avoid the stress increase of adjacent intervertebral discs, and its long-term implantation in the human body is expected to reduce the incidence of degeneration of adjacent intervertebral discs. Key words: Spinal fractures; Lumbar vertebrae; Prosthesis implantation; Finite element analysis; Biomechanics

Numerical simulation and experimental tests on a lumbar disc prosthesis

Many solutions were adopted to substitute the intervertebral disc when it is damaged and has to be removed, in order to assure stability of the spine as well as some degree of freedom of the spine segment. The disc prostheses currently on the market, however, are frequently subject to failure due to wear and degeneration of the material or stress shielding.Aim of the present research is the design a new solution for the artificial intervertebral disc and to perform a numerical-experimental analysis on them. Starting from the tests performed on the hyperelastic materials considered to substitute the intervertebral disc, numerical models were carried out on the new devices.The paper prosecutes with the experimental analysis, under simple static compression tests. Finally, numerical and experimental comparison was made in order to evaluate the best prosthesis among the different adopted models.

P81 - Clinical Results, Range of Motion and Centers of Rotation with the Six Degrees of Freedom Viscoelastic LPESP Lumbar Disc Prosthesis: a 5-Year Prospective Study in 76 Patients

P81 - Clinical Results, Range of Motion and Centers of Rotation with the Six Degrees of Freedom Viscoelastic LPESP Lumbar Disc Prosthesis: a 5-Year Prospective Study in 76 Patients

In vitro analysis of circumferential joint replacement, including bilateral facet joint replacement with lateral lumber disc prosthesis: a parametric investigation of disc sizing.

Lateral lumbar disc prosthesis (LLDP) is an innovative device used to restore motion in select patients through a lateral retroperitoneal approach. No in vitro biomechanical studies have been published. Further, the potential for in toto circumferential joint restoration when use of this anterior disc is combined with facet replacement remains unqualified but signifies a potentially interesting clinical direction. Researchers conducted a biomechanical feasibility study of an LLDP designed to investigate parameters of disc sizing used with bilateral facet joint replacement in a cadaveric model. Tested constructs at L4-L5 included (1) intact, (2) LLDP, (3) LLDP+ wide discectomy, (4) LLDP+ bilateral facetectomy, and (5) LLDP+ bilateral facet joint replacement (BFJR). Investigators tested instrumented constructs (2-5) with an LLDP at compact-fit and lax-fit heights and used raw data to perform statistical analysis by repeated measures analysis of variance (ANOVA), along with Student-Newman-Keuls post hoc analysis (p≤0.05). Increased height of the LLDP resulted in significantly less motion compared with intact. Widening the discectomy while using lax-fit sizing led to motion similar to intact in flexion-extension. As expected, motion was greater with lax-fit height than with compact-fit height in all loading modes and constructs, as is noted with a widened discectomy. The L4-L5 center of rotation was maintained regardless of placement of the LLDP. After bilateral facetectomy, reconstruction of the three-joint complex achieved by combining the LLDP with BFJR may provide a viable alternative to current clinical treatment regimens.

Recent Advances in Finite Element Applications in Artificial Lumbar Disc Replacement

As a new choice for the treatment of degenerative lumbar disease, artificial lumbar disc replacement has been widely used in clinical surgery. The finite element is a very effective method to predict and simulate the surgery effect. The purpose of this paper is to review the applications of finite element in artificial lumbar disc replacement, such as design of artificial lumbar disc prosthesis, risk and effect evaluation of artificial lumbar disc replacement, and assessment of operation methods. Lastly, we discuss the future development of finite element method applied in this field, including personalized design of the prosthesis, postoperative behavior guide, and artificial lumbar disc replacement combined with fusion surgery. In conclusion, as an invaluable complement to biomechanical experiments and clinical studies, the finite element method makes important contributions to our understanding of biomechanics of intervertebral disc, and plays an important role in the field of artificial lumbar disc replacement.

A 5-year Follow-up of a Controlled Mobile Core Lumbar Disc Prosthesis: Clinical Results

Purpose: Total disc replacement is an alternative to arthrodesis in degenerative disc disease in young patients suffering from persistent chronic back pain refractory to conservative treatments. The aim of this study is to assess the efficacy and safety of a mobile-core lumbar prosthesis. This study reports both clinical (Part 1) and radiological (Part 2) assessments. Methods: Four hundred and eleven patients were included in a prospective and multicenter study with 5-year follow-up. The clinical assessment investigated ODI, VAS (lumbar and radicular) score, quality of life (SF-36), medication consumption, professional status, and complication occurrence after surgery. Results: ODI significantly decreased at 5 years after surgery with an average improvement of 27.3%. Low back pain and radicular pain significantly decreased. SF-36 significantly increased for both the mental and physical components. Medication consumption also significantly decreased at 5 years. Professional status was improved with an increase in the proportion of working patients and a decrease in sick leave up to 5 years after surgery. All complications were reported with an overall reoperation rate of 14.6% (regardless the cause and the level of the lumbar spine). Conclusion: This study showed satisfactory clinical results and patient satisfaction at 5 years’ follow-up and confirmed the safety and efficacy of this lumbar total disc prosthesis with specific controlled-mobility core.

Clinical and Radiological Assessment of Lumbar Disc Prosthesis with Controlled Mobility with Five-Year Follow-Up: A Prospective Study on 411 Patients

Clinical and Radiological Assessment of Lumbar Disc Prosthesis with Controlled Mobility with Five-Year Follow-Up: A Prospective Study on 411 Patients

Sacroiliac Joint Syndrome 10 Years after Lumbar Arthroplasty: The Importance of Spinopelvic Alignment

Introduction Sagittal balance is an independent predictor of outcomes in spinal care and several authors focused their attention on the lumbar lordosis restoration as the key point to prevent secondary sacroiliac joint dysfunction (SIJD) after fusion. On the other hand, lumbar disc arthroplasty allows preservation of motion avoiding increased stress on the spinopelvic junction and preventing iatrogenic sagittal imbalance. Methods We analyze the incidence of a secondary SIJD and the spinopelvic alignment on a series of 31 consecutive lumbar disc prosthesis with a 10-year follow-up. Results Sagittal balance assessment showed no significant variation of preoperative spinopelvic parameters. Four patients (12%) presented a symptomatic SIJD. Only two of them required a percutaneous SIJ fixation. Both of them presented a fused L5–S1 prosthesis. Conclusions Very few studies are focused on the topic of SIJ deterioration after lumbar arthroplasty and, at the best of our knowledge, the present article is the first with such a long follow-up. After 10 years of the surgery 12% of our patients presented a symptomatic SIJ dysfunction, less than the percentage reported in the literature after lumbosacral fusion. The low rate of SIJD 10 years after lumbar arthroplasty might be explained by the preservation of the spinopelvic balance.

Sacroiliac joint syndrome 10years after lumbar arthroplasty: the importance of spinopelvic alignment.

Sagittal balance is an independent predictor of outcomes in spinal care and several authors focused their attention on the lumbar lordosis restoration as the key point to prevent secondary sacroiliac joint dysfunction (SIJD) after fusion. On the other hand, lumbar disc arthroplasty allows preservation of motion avoiding increased stress on the spinopelvic junction and preventing iatrogenic sagittal imbalance. We analyze the incidence of a secondary SIJD and the spinopelvic alignment on a series of 31 consecutive lumbar disc prosthesis with a 10-year follow-up. Sagittal balance assessment showed no significant variation of preoperative spinopelvic parameters. Four patients (12%) presented a symptomatic SIJD. Only two of them required a percutaneous SIJ fixation. Both of them presented a fused L5-S1 prosthesis. The low rate of SIJD 10years after lumbar arthroplasty might be explained by the preservation of the spinopelvic balance.