Mechanical characterization and cytocompatibility of linoleic acid modified bone cement for percutaneous cement discoplasty.

Minimally invasive spine treatments have been sought after for elderly patients with comorbidities suffering from advanced degenerative disc disease. Percutaneous cement discoplasty (PCD) is one such technique where cement is injected into a degenerated disc with a vacuum phenomenon to relieve patients from pain. Adjacent vertebral fractures (AVFs) are however an inherent risk, particularly for osteoporotic patients, due to the high stiffness of the used cements. While low-modulus cements have been developed for vertebroplasty through the addition of linoleic acid, there are no such variations with a high-viscosity base cement, which is likely needed for the discoplasty application. Therefore, a low-modulus polymethyl methacrylate was developed by the addition of 12%vol. linoleic acid to a high-viscosity bone cement (hv-LA-PMMA). Initial experimental validation of the cement was performed by mechanical testing under compression over a period of 24 weeks, after storage in 37 °C phosphate buffer saline (PBS) solution. Furthermore, cement extracts were used to evaluate residual monomer release and the cytotoxicity of hv-LA-PMMA using fibroblastic cells. Relative to the base commercial cement, a significant reduction of Young's modulus and compressive strength of 36% and 42% was observed, respectively. Compression-tension fatigue tests at 5 MPa gave an average fatigue limit of 31,078 cycles. This was higher than another low-modulus cement and comparable to the fatigue properties of the disc annulus tissue. Monomer release tests showed that hv-LA-PMMA had a significantly higher release between 24 h and 7 days compared to the original bone cement, similarly to other low-modulus cements. Also, the control cement showed cytocompatibility at all time points of extract collection for 20-fold dilution, while hv-LA-PMMA only showed the same for extract collections at day 7. However, the 20-fold dilution was needed for both the control and the hv-LA-PMMA extracts to demonstrate more than 70% fibroblast viability at day 7. In conclusion, the mechanical testing showed promise in the use of linoleic acid in combination with a high-viscosity PMMA cement to achieve properties adequate to the application. Further testing and in vivo studies are however required to fully evaluate the mechanical performance and biocompatibility of hv-LA-PMMA for possible future clinical application.

Finite element analysis of biomechanical effects of percutaneous cement discoplasty in scoliosis.

OBJECTIVE: To investigate the effect of bone cement on the vertebral body and biomechanical properties in percutaneous cement discoplasty (PCD) for degenerative lumbar disc disease. METHODS: Three-dimensional reconstruction of L2 ~ L3 vertebral bodies was performed in a healthy volunteer, and the corresponding finite element model of the spine was established. Biomechanical analysis was performed on the changes in stress distribution in different groups of models by applying quantitative loads. RESULTS: Models with percutaneous discoplasty (PCD) showed improved stability under various stress conditions, and intervertebral foraminal heights were superior to models without discoplasty. CONCLUSION: Cement discoplasty can improve the stability of the vertebral body to a certain extent and restore a certain height of the intervertebral foramen, which has a good development prospect and potential.

Efficacy and safety of percutaneous cement discoplasty in the management of degenerative spinal diseases: A systematic review and meta-analysis.

BACKGROUND: Percutaneous cement discoplasty (PCD) is a minimally invasive procedure. We aim to explore the efficacy and indication(s) of PCD in patients with degenerative disc disease (DDD). METHODS: The search was conducted across Ovid MEDLINE, Ovid Embase, and PubMed. Data on study design, patient demographics, pre- and post-procedure Visual Analog Scale (VAS) and Oswestry Disability Index (ODI) scores, and complications were extracted. Inclusion criteria focused on adult patients with degenerative spinal diseases treated with cement discoplasty. The overall effect size was evaluated using a forest plot, and heterogeneity was assessed using the I2 statistic and chi-squared test. RESULTS: The search strategy yielded six studies, which included 336 patients (73.8% female, 26.2% male) with a mean average age of 74.6 years. VAS scores were reported in all studies, showing a significant difference between pre- and post-PCD pain scores (Weighted Mean Difference [WMD]: -3.45; 95% CI: -3.83, -3.08; I2 = 15%; P < .001). ODI scores were reported in 83% of studies, with a significant difference between pre- and post-PCD scores (WMD: -22.22; 95% CI: -25.54, -18.89; I2 = 61%; p < .001). Complications reported included infections, thrombophlebitis, vertebral fractures, disc extrusion, and the need for further operations. CONCLUSIONS: The analysis showed clinically significant improvements in pain and functional disability based on VAS and ODI scores. However, due to methodological limitations and a high risk of bias, the validity and generalizability of the findings are uncertain. Despite these issues, the results provide preliminary insights into PCD's potential efficacy and can guide future research to address current limitations.

Complication Pattern After Percutaneous Cement Discoplasty: Identification of Factors Influencing Reoperation and Length of Hospital Stay.

OBJECTIVE: Percutaneous cement discoplasty (PCD) was introduced to treat symptomatic vertical instability of the lumbar spine in a minimally invasive way. The aim of the present study was to analyze the complication pattern after PCD and to identify factors that predict the chance of cement leakage, reoperation, and length of hospital stay (LOS). METHODS: patients were treated with PCD within the study period. Clinical features and complications were analyzed by applying descriptive statistics, whereas perioperative factors predictive of cement leakage, reoperation, and LOS were identified by regression models. RESULTS: Cement leakage rate was 30.4% in the total cohort; however, only fifth of them were symptomatic. Cement leakage itself did not have a significant influence on clinical outcome. Other complications and nonsurgical adverse events were registered only in 2.0% of cases. Age, subcutaneous fat tissue thickness, low viscosity cement, lower level of surgeon's experience and the number of operated levels were identified as risk factors of cement leakage (P < 0.01; c-index = 0.836). Type of procedure, Charlson comorbidity score, reoperation, and nonsurgical adverse events significantly increased the LOS (P < 0.01). Cement leakage, early surgical practice, and increased subcutaneous fat tissue thickness were risk factors for reoperation (P < 0.01; c-index = 0.72). CONCLUSIONS: PCD is a relatively safe and effective procedure for treating spinal instability caused by advanced-stage disc degeneration characterized by vacuum phenomenon. Cement leakage is not uncommon but is only a radiologic complication without clinical consequences in most cases. On the other hand, it can increase the LOS and is a significant risk factor for reoperation.

Association between Modic changes and intervertebral vacuum phenomenon severity in patients undergoing percutaneous cement discoplasty.

BACKGROUND: Modic changes and intervertebral vacuum phenomenon (IVP) are considered spinal degenerative changes. The correlation between Modic and IVP has not been analyzed in the literature. PURPOSE: To analyze the correlation between IVP severity, Modic changes, and subchondral sclerosis across the lumbar spine in patients with lumbar degeneration. MATERIAL AND METHODS: This is a retrospective study analyzing patients who underwent percutaneous cement discoplasty at a single institution between 2015 and 2020. Preoperative magnetic resonance imaging and computed tomography scans were analyzed to make the measurements. Modic type and grade as well as severity of IVP were preoperatively measured. The association between Modic type, grade, subchondral sclerosis, and the presence of IVP was analyzed. RESULTS: In total, 110 patients (mean age = 77.03 ± 7.1 years) were finally included in the study. Per level correlation analysis showed a significant positive association between IVP and Modic type, IVP and Modic grade, and IVP and subchondral sclerosis. Moreover, subchondral sclerosis was significantly associated with Modic type and grade. CONCLUSION: Our study showed a significant positive correlation among Modic changes, IVP, and subchondral sclerosis throughout the lumbar spine. Our findings support the theory that endplate degeneration parameters are associated with the presence and severity of IVP.

Quasi-static and dynamic mechanical properties of a linoleic acid-modified, low-modulus bone cement for spinal applications.

Background: Polymethylmethacrylate (PMMA) bone cement is extensively used in spinal procedures such as vertebroplasty and kyphoplasty, while its use in percutaneous cement discoplasty (PCD) is not yet widely spread. A main issue for both application sites, vertebra and disc, is the mismatch in stiffness between cement and bone, potentially resulting in adjacent vertebral fractures and adjacent segment disease. Tailoring the cement modulus using additives is hence an interesting strategy. However, there is a lack of data on the tensile and tension-compression fatigue properties of these cements, relevant to the newly researched indication of PCD. Method: A commercial PMMA cement (VS) was modified with 12%vol of linoleic acid (VSLA) and tested for quasi-static tensile properties. Additionally, tension-compression fatigue testing with amplitudes ranging from +/-5MPa to +/-7MPa and +/-9MPa was performed, and a Weibull three-parameter curve fit was used to calculate the fatigue parameters. Results: Quasi-static testing revealed a significant reduction in VSLA's Young's Modulus (E=581.1±126.4MPa) compared to the original cement (E=1478.1±202.9MPa). Similarly, the ultimate tensile stress decreased from 36.6±1.5MPa to 11.6±0.8MPa. Thus, VSLA offers improved compatibility with trabecular bone properties. Fatigue testing of VSLA revealed that as the stress amplitude increased the Weibull mean number decreased from 3591 to 272 and 91 cycles, respectively. In contrast, the base VS cement reached run-out at the highest stress amplitude. However, the lowest stress amplitude used exceeds the pressures recorded in the disc in vivo, and VSLA displayed a similar fatigue life range to that of the annulus fibrosis tissue. Conclusions: While the relevance of fully reversed tension-compression fatigue testing can be debated for predicting cement performance in certain spinal applications, the results of this study can serve as a benchmark for comparison of low-modulus cements for the spine. Further investigations are necessary to assess the clinical feasibility and effectiveness of these cements.

Biomechanical consequences of cement discoplasty: An in vitro study on thoraco-lumbar human spines.

With the ageing of the population, there is an increasing need for minimally invasive spine surgeries to relieve pain and improve quality of life. Percutaneous Cement Discoplasty is a minimally invasive technique to treat advanced disc degeneration, including vacuum phenomenon. The present study aimed to develop an in vitro model of percutaneous cement discoplasty to investigate its consequences on the spine biomechanics in comparison with the degenerated condition. Human spinal segments (n = 27) were tested at 50% body weight in flexion and extension. Posterior disc height, range of motion, segment stiffness, and strains were measured using Digital Image Correlation. The cement distribution was also studied on CT scans. As main result, percutaneous cement discoplasty restored the posterior disc height by 41% for flexion and 35% for extension. Range of motion was significantly reduced only in flexion by 27%, and stiffness increased accordingly. The injected cement volume was 4.56 ± 1.78 ml (mean ± SD). Some specimens (n = 7) exhibited cement perforation of one endplate. The thickness of the cement mass moderately correlated with the posterior disc height and range of motion with different trends for flexions vs. extension. Finally, extreme strains on the discs were reduced by percutaneous cement discoplasty, with modified patterns of the distribution. To conclude, this study supported clinical observations in term of recovered disc height close to the foramen, while percutaneous cement discoplasty helped stabilize the spine in flexion and did not increase the risk of tissue damage in the annulus.

Intervertebral vacuum phenomenon - prevalence and severity CT-scan analysis in patients older than 50 years: a retrospective cohort study.

BACKGROUND: Chronic low back pain secondary to degenerative changes in the spine is a common cause of disability, and disc degeneration is one of the most frequent imaging findings. Intervertebral vacuum phenomenon (IVP) is usually observed in advanced degeneration. Recently, this phenomenon has gained interest due to a relatively new surgical technique called percutaneous discoplasty, aimed at treating low back pain secondary to degenerative disc disease in elderly patients. PURPOSE: To analyze the prevalence and related factors of the vacuum phenomenon in adult patients. MATERIAL AND METHODS: A retrospective cohort study was performed of patients who underwent abdominal computed tomography (CT) for non-spine-related reasons. Age, body mass index, smoking, and CT-based characteristics as presence of IVP, subchondral sclerosis, and facet joint degeneration at the lumbar spine from L1 to the sacrum were included in order to determine the prevalence of the vacuum phenomenon in this population and establish a relationship between this condition and patient demographics and other signs of spine degeneration, such as sclerosis and facet joint disease. RESULTS: A total of 238 patients were included in the study (114 men, 124 women; mean age = 75.6 ± 12.3 years. In total, 91 (38%) patients had at least one level of IVP; 59 (25%) patients exhibited subchondral sclerosis, and 235 (98%) facet joint degeneration. Among risk factors, age, smoking, and subchondral sclerosis were significantly associated with the presence of vacuum. CONCLUSION: IVP was present in 38% of participants. Risk factors associated with vacuum were age, smoking, and subchondral sclerosis.

Percutaneous vertebral-disc plasty for thoracolumbar very severe osteoporotic vertebral compression fractures: A randomized controlled study.

Purpose: To compare the clinical outcomes and radiological parameters of patients undergoing percutaneous vertebroplasty (PVP) versus those undergoing percutaneous vertebral-disc plasty (PVDP) for back pain, segmental instability, and kyphosis due to thoracolumbar very severe osteoporotic vertebral compression fractures (vsOVCFs). Methods: This prospective randomized controlled study included elderly patients with thoracolumbar vsOVCFs. All the patients were randomly allocated into the PVP group (who underwent conventional PVP) and the PVDP group (who underwent PVP combined percutaneous cement discoplasty). The visual analogue scale (VAS), Oswestry Disability Index (ODI), local kyphosis angle, and disc height were recorded preoperatively and postoperatively. Results: Significant postoperative improvements in the VAS, ODI, and the local kyphosis angle (LKA) were shown, compared with the preoperative values in both groups (p < 0.05). The average VAS, ODI, and LKA for patients in the PVP group were increased compared to those in the PVDP group observed at the last follow-up (p < 0.05). The DHA, DHP, and LKA were seen to be maintained in the PVDP group at the last follow-up (p > 0.05). The change was significantly lower in the PVDP group at the last follow-up in those parameters (p < 0.05). Conclusion: PVDP may be a feasible and effective technique for the treatment of very severe OVCFs, that can restore intervertebral height, provide segmental stabilizing and relieve back pain in the short term.

[Biomechanical evaluation of effects of percutaneous cement discoplasty and percutaneous cement interbody fusion on spinal stability].

Objective: To investigate the effects of percutaneous cement discoplasty (PCD) and percutaneous cement interbody fusion (PCIF) on spinal stability by in vitro biomechanical tests. Methods: Biomechanical test was divided into intact (INT) group, percutaneous lumbar discectomy (PLD) group, PCD group, and PCIF group. Six specimens of L 4, 5 (including vertebral bodies and intervertebral discs) from fresh male cadavers were taken to prepare PLD, PCD, and PCIF specimens, respectively. Before treatment and after the above treatments, the MTS multi-degree-of-freedom simulation test system was used to conduct the biomechanical test. The intervertebral height of the specimen was measured before and after the axial loading of 300 N, and the difference was calculated. The range of motion (ROM) and stiffness of the spine in flexion, extension, left/right bending, and left/right rotation under a torque of 7.5 Nm were calculated. Results: After axial loading, the change of intervertebral height in PLD group was more significant than that in other three groups ( P<0.05). Compared with INT group, the ROM in all directions significantly increased and the stiffness significantly decreased in PLD group ( P<0.05). Compared with INT group, the ROM of flexion, extension, and left/right rotation in PCD group significantly increased and the stiffness significantly decreased ( P<0.05); compared with PLD group, the ROM of flexion, extension, and left/right bending in PCD group significantly decreased and the stiffness significantly increased ( P<0.05). Compared with INT group, ROM of left/right bending in PCIF group significantly decreased and stiffness significantly increased ( P<0.05); compared with PLD group, the ROM in all directions significantly decreased and the stiffness significantly increased ( P<0.05); compared with PCD group, the ROM of flexion, left/right bending, and left/right rotation significantly decreased and stiffness significantly increased ( P<0.05). Conclusion: Both PCD and PCIF can provide good biomechanical stability. The former mainly affects the stiffness in flexion, extension, and bending, while the latter is more restrictive on lumbar ROM in all directions, especially in bending and rotation.

Biomechanical effects of cement discoplasty on the lumbar spinal unit.

Background: Percutaneous cement discoplasty (PCD) is used to treat patients with low back and leg pain due to the intervertebral disc vacuum phenomena. Whether PCD can restore lumbar spinal stability remains unknown. Objective: The purpose of our in vitro study was to evaluate the biomechanical changes brought about by PCD. Methods: Eight fresh pig lumbar spines were tested in the following order: intact, after nucleotomy, and after discoplasty. Flexion/extension, lateral bending, and axial rotation were induced by pure moments. The range of motion and neutral zone were recorded. A CT scan was performed to assess the injection volume of the bone cement and to observe whether the bone cement was fractured. After removing the facet joint, a compression failure test was conducted to observe the fracture of bone cement. Results: Compared with nucleotomy, range of motion (ROM) after discoplasty was reduced only in lateral flexion (P < 0.05). The results of the neutral zone showed that the neutral zones in flexion-extension and lateral bending were significantly reduced after discoplasty (P < 0.05). The neutral zone was more sensitive to changes in lumbar stability than ROM. Bone cement slides were observed during the biomechanical test. The CT scan and compression failure test showed that bone cement fracture was more likely to occur at the puncture channel in the annulus fibrosus region. Conclusion: In all, the biomechanical study indicates that discoplasty helps enhance the stability of the lumbar spine in flexion-extension and lateral bending, which explains how PCD works for low back pain. Fractures and sliding of bone cement were observed after discoplasty, and this was more likely to occur at the puncture channel in the annulus fibrosus region. This suggests that bone cement displacement after PCD may cause nerve compression.

Percutaneous Cement Discoplasty in Degenerative Spinal Disease: Systematic Review of Indications, Clinical Outcomes, and Complications.

BACKGROUND: Percutaneous cement discoplasty (PCD) is a minimally invasive surgical procedure that can provide a segmental stabilizing and indirect decompression effect in the case of severely degenerated discs characterized by vacuum phenomenon. This systematic review aims to analyze the available literature relating to correct indications and clinical and radiologic efficacy of PCD in patients affected by advanced degenerative spine conditions. METHODS: The search was conducted according to the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) guideline. Comprehensive research of PubMed, Scopus, and OVID databases was made using the following Mesh terms: ((cement) AND (discoplasty) AND ((vertebral) OR (spinal) OR (spine))). Modal distribution was used to assess the most frequent levels of PCD per patient. Quality assessment of each article was performed according to the Oxford Level of Evidence, Methodological Index for Non-Randomized studies, and Risk of Bias in Non-Randomized Studies score by 2 authors. RESULTS: After the databases search, 5 full-text articles were included in the systematic review for a total of 291 patients (218 females and 73 males). Median PCD levels were 2.2. Despite promising clinical results, the methodologic index showed poor Methodological Index for Non-Randomized and Risk of Bias in Non-Randomized Studies scores. CONCLUSIONS: PCD provides good clinical results in elderly patients, especially for pain relief. However, the current literature is poor and the article included in the systematic review showed a poor methodologic score, which could affect the conclusions.

An ex-vivo model for the biomechanical assessment of cement discoplasty.

Percutaneous Cement Discoplasty (PCD) is a surgical technique developed to relieve pain in patients with advanced degenerative disc disease characterized by a vacuum phenomenon. It has been hypothesized that injecting bone cement into the disc improves the overall stability of the spinal segment. However, there is limited knowledge on the biomechanics of the spine postoperatively and a lack of models to assess the effect of PCD ex-vivo. This study aimed to develop a biomechanical model to study PCD in a repeatable and clinically relevant manner. Eleven ovine functional spinal units were dissected and tested under compression in three conditions: healthy, injured and treated. Injury was induced by a papain buffer and the treatment was conducted using PMMA cement. Each sample was scanned with micro-computed tomography (CT) and segmented for the three conditions. Similar cement volumes (in %) were injected in the ovine samples compared to volumes measured on clinical PCD CT images. Anterior and posterior disc heights decreased on average by 22.5% and 23.9% after injury. After treatment, the anterior and posterior disc height was restored on average to 98.5% and 83.6%, respectively, of their original healthy height. Compression testing showed a similar stiffness behavior between samples in the same group. A decrease of 51.5% in segment stiffness was found after injury, as expected. The following PCD treatment was found to result in a restoration of stiffness-showing only a difference of 5% in comparison to the uninjured state. The developed ex-vivo model gave an adequate representation of the clinical vacuum phenomena in terms of volume, and a repeatable mechanical response between samples. Discoplasty treatment was found to give a restoration in stiffness after injury. The data presented confirm the effectiveness of the PCD procedure in terms of restoration of axial stiffness in the spinal segment. The model can be used in the future to test more complex loading scenarios, novel materials, and different surgical techniques.

Biomechanical Evaluation of Spinal Column after Percutaneous Cement Discoplasty: A Finite Element Analysis.

OBJECTIVE: To compare the biomechanical properties of percutaneous cement discoplasty (PCD) in the spinal column between different implant-endplate friction. METHODS: A validated L3-Scarumfinite element (FE) model was modified for simulation. In the PCD model, the L4/5 level was modified based on model 1 (M1) and model 2 (M2). In M1, the interaction between bone cement and endplate was defined as face-to-face contact with a friction coefficient of 0.3; in M2, the contact was defined as a Tie constraint. 7.5 N m moments of four physiological motions and axial load of 15, 100 and 400 N preload were imposed at the top of L3. The range of motion (ROM) and interface stress analysis of endplates, annulus fibrosus and bone cement of the operated level were calculated for comparisons among the three models. RESULTS: The ROM of M1 and M2 increased when compared with the intact model during flexion (FL) (17.5% vs 10.0%), extension (EX) (8.8% vs -8.8%), left bending (LB) (19.0% vs -17.2%) and left axial rotation (LR) (34.6% vs -3.8%). The stress of annulus fibrosus in M1 and M2 decreased in FL (-48.4% vs -57.5%), EX (-25.7% vs -14.7%), LB (-47.5% vs -52.4%), LR (-61.4% vs -68.7%) and axis loading of 100 N (-41.5% vs -15.3%), and 400 N (-27.9% vs -27.3%). The stress of upper endplate of M1 and M2 increased in FL (24.6% vs 24.7%), LB (82.2% vs 89.5%), LR (119% vs 62.4%) and axis loading of 100 N (64.6% vs 45.5%), and 400 N (58.2% vs 24.3%), but was similar in EX (2.9% vs 0.3%). The stress of lower endplate of M1 and M2 increased in FL (170.9% vs 175.0%), EX (180.8% vs 207.7%), LB (302.6% vs 274.7%), LR (332.4% vs 132.8%) and axis loading of 100 N (350.7% vs 168.6%), and 400 N (165.2% vs 106.7%). CONCLUSION: Percutaneous cement discoplasty procedure could make effect on the mobility or stiffness. The fusion of bone cement and endplate might have more biomechanical advantages, including of the decreasing rate of implant subsidence and dislocation, and the increase spine stability.

Biomechanical evaluation of percutaneous cement discoplasty by finite element analysis.

BACKGROUND: Percutaneous cement discoplasty (PCD) is a minimally invasive treatment for degenerative lumbar spine disease, but the relationship between decompression effect on the nerve root and different doses of bone cement is uncertain. PURPOSE: To investigate the indirect decompression effect of cement with different doses on nerve roots and the biomechanical changes on the spine during PCD using finite element analysis (FEA). METHODS: FEA was adapted to analyze the mechanical changes in the lumbar vertebrae before and after the application of PCD.CT scan images of adult males were utilized to establish a finite element model of the lumbar vertebral body using mimics and Pro/E software. The images were divided into four models: the normal model (normal, model N), the disc degeneration model (high, model H), the intervertebral disc injected with 3 mL of bone cement (model H1), and the intervertebral disc injected with 5 mL of bone cement (model H2). All models were analyzed using the ABAQUS6.14.2 software. The normal physiological movements were simulated, and the mechanical changes in the lumbar vertebrae were observed prior to and after the cement filling application. RESULTS: The stress of the nerve root in model H was the largest. The nerve root stress in the model H2 was the smallest during flexion, extension, left bending, right bending, left rotation, and right rotation at 90%, 44%, 25%, 56%, 56%, and 51% of the normal benchmark, respectively. After the injection of bone cement, the nerve root stress is reduced. The greater the amount of cement, the lesser the nerve root stress. The motion was reduced in models H, H1, and H2, and there were differences between models H1 and H2. Cartilage endplate stress was less in model H2 than in model H1. CONCLUSIONS: The nerve root stress increased after degeneration and decreased after intervertebral height recovery through cement injection, resulting in a significant indirect decompression effect.The stress of the nerve root decreased with the increase in the amount of cement injection.

Critical Review of the State-of-the-Art on Lumbar Percutaneous Cement Discoplasty.

Interbody fusion is the gold standard surgery to treat lumbar disc degeneration disease but can be a high-risk procedure in elderly and polymorbid patients. Percutaneous Cement Discoplasty (PCD) is a minimally invasive technique developed to treat advanced stage of disc degeneration exhibiting a vacuum phenomenon. A patient-specific stand-alone spacer is created by filling the disc with polymethylmethacrylate cement, allowing to recover the disc height and improve the patient's conditions. As it has recently been introduced in the lumbar spine, this review aims to present a transversal state-of-the-art of the surgery from its clinical practice and outcome to biomechanical and engineering topics. The literature was searched across multiple databases using predefined keywords over no limited period of time. Papers about vertebroplasty were excluded. Among 466 identified papers, the relevant ones included twelve clinical papers reporting the variations of the surgical technique, follow-up and complications, four papers reporting biomechanical ex vivo and numerical tests, and four letters related to published clinical papers. Papers presenting the operative practice are reported, as well as follow-ups up to four years. The papers found, consistently reported that PCD significantly improved the clinical status of the patients and maintained it after two years. Spine alignment was impacted by PCD: the sacral slope was significantly reduced, and disc height increased. The foramen opening correlated to the volume of injected cement. Substitutes to the acrylic cement exhibited better osteointegration and mechanical properties closer to bone tissue. Finally, limitations and risks of the surgery are discussed as well as potential improvements such as the development of new filling materials with better mechanical properties and biological integration or the investigation of the inner disc.

Cement discoplasty for managing lumbar spine pseudarthrosis in elderly patients: a less invasive alternative approach for failed posterior lumbar spine interbody fusion.

PURPOSE: A retrospective cohort study was performed to evaluate pseudoarthrosis treatment results by injection of cement in disc space of failed fusion in posterior lumbar interbody fusion in patients above 65 years. METHODS: Forty-five patients above 65 years with symptomatic pseudarthrosis after lumbar spine fusion were treated by cement injection in the affected disc space. RESULTS: There were 30 females and 15 males. The mean age at the operation was 74 ± 6.5 years (range 65-89). Discoplasty was performed after the primary fusion operations after a mean of 14 ± 1.3 months (range 12-24). The mean preoperative VAS was 7.5 (range 6-9), and ODI was 36 (range 30-45). Cement injection was done at one level in most of the cases (35 patients). In seven cases, two injection levels were done, and in three cases, three levels. Twenty-three patients had discoplasty only, while 22 had discoplasty and screws change, including 14 cases of extension of the instrumentation. The mean postoperative follow-up was 32 ± 6.5 months. The VAS improved to 3.5 (range 2-5) (p = 0.02) and ODI to 12.3 (range 5-35) (p = 0.001). Reoperation was indicated in two (4%) patients by screws loosening. Asymptomatic cement leakage occurred in the paravertebral space in seven cases (15.5%). CONCLUSION: Cement discoplasty offers a less invasive reliable surgical solution in elderly patients with symptomatic lumbar pseudarthrosis in the elderly patients. In cases with screw loosening, discoplasty should be combined with screw revision.

Invasive surgical procedures for the management of internal derangement of the temporomandibular joint: a systematic review and meta-analysis regarding the effects on pain and jaw mobility.

OBJECTIVES: This systematic review compared minimally and invasive surgical procedures to manage arthrogenous temporomandibular joint (TMJ). MATERIALS AND METHODS: The review included clinical trials assessing surgical procedures of arthrogenous temporomandibular disorder (TMD) management by carrying out comparisons within the same surgical procedure (pre- and post-treatment) as well as between different surgical procedures. Meta-analyses were conducted only for similar comparison reporting the same outcome measures, visual analog scale (VAS) values to evaluate pain and maximum incisal opening (MIO) values. RESULTS: Of the 1,015 studies identified by the search strategy, 26 were selected for full-text reading, and 19 were included in the review. Of these, 16 studies were included in the meta-analysis and 3 in the qualitative analysis. The VAS scores showed significantly lower values after discectomies (p < 0.001) and discoplasties (p < 0.001) in the within-group comparison. Moreover, significantly lower VAS scores and higher MIO values were observed after discectomy compared to arthroscopy, eminectomy, and discoplasty (p < 0.05). CONCLUSION: The findings of this systematic review suggest that although significantly lower VAS scores and higher MIO values were observed after discectomy, the currently available scientific evidence is unclear, and the use of invasive surgical procedures should not be implemented as an efficient first-line treatment option for arthrogenous TMD management. CLINICAL SIGNIFICANCE: VAS and MIO outcomes could be insufficient to describe the success or failure of open surgical procedures like discectomy and discoplasty.

Discoplasty as a salvage technique for pseudoarthrosis following multilevel TLIFS: A case report.

BACKGROUND: Pseudoarthrosis, often defined as a failure to achieve osseous fusion by the 1-year post-operative time point. Despite its relatively high prevalence, there is still lack of clinical evidence on salvage options for lumbar pseudoarthrosis. Lumbar interbody fusion is generally accepted as a useful surgical treatment for patients with pseudoarthrosis. Several techniques are available to achieve stabilization of the lumbar spine including the anterior lumbar interbody fusion (ALIF), posterior lumbar interbody fusion (PLIF), transforaminal interbody fusion (TLIF), direct lateral interbody fusion, posterolateral only (intertransverse) fusion, and facet or pedicle screw/rod placement. We present a case report of discoplasty as a salvage option for pseudoarthrosis following lumbar fusion surgery using multilevel TLIFs. METHOD: This study is a case report. A female patient, 79 year old, came with recurrent backpain at the lumbar area that got worse during the past 3 months. She underwent posterior lumbar fusion surgery of L3-S1 by pedicle screw and transforaminal interbody fusion at the level of L3-S1. Three years later she experienced another episode of back pain and underwent pedicle screws removal to improve her pain. Two years later complaint reappeared. The pain was rated 7/10 in standing position and improved to 5/10 with resting in horizontal position. We followed up this patient for 1 month after surgery. RESULT: After surgery, VAS score was decreased from 7/10 into 1/10 in standing position and patient was able to stand and walk using a walker. Postoperatively plain radiograph was performed and there was no complication. In a month follow up, the VAS score was 1/10 with ODI score reduces significantly from 38% to 4% showing only minimal disability. CONCLUSION: Salvage discoplasty for pseudoarthrosis following posterior lumbar fusion surgery is rarely reported, but it appears to be viable option aside from ALIF that results in significant improvement in clinical outcomes. Discoplasty offers a less invasive solution in elderly patients which significantly reduces the symptoms and improves the quality of life of the affected patients.