Functionalization of Osteoplastic Material with Human Placental Growth Factor and Assessment of Biocompatibility of the Resulting Material In Vitro.

This article provides the results of a study of the interaction of placental growth factor with adipose-derived stem cells (ASCs) of various origins, as well as the possibility of generating osteoplastic material based on xenogeneic matrix functionalization with human placental growth factor (PLGF). It is demonstrated that the greatest release of this factor from the functionalized material into the medium occurs during the first 3 h of contact with the model medium, but then the levels of the factor being released fall sharply, although release did continue throughout the 7 days of observation. The modified material was not cytotoxic, and its surface provided good cell adhesion. During 3 days of cultivation, the ASCs proliferated and migrated more actively on the surfaces of the modified material than on the surfaces of the control material. This study can serve as the basis for the development of original methods to functionalize such osteoplastic material by increasing PLGF immobilization by creating stronger bonds in order to regulate both factor dosage and the dynamics of the factor release into the environment. Further studies in experimental animals should facilitate assessment of the effectiveness of the functionalized materials. Such studies will be useful in the development of osteoplastic materials with new properties resulting from the inclusion of growth factors and in research on their biological activity.

Supplementary posterior fusion in patients operated on employing TLIF may decrease the instrumentation failure rate.

Background: It is supposed that additional posterior fusion may provide additional stability of the pedicle screw; however, the clinical impact of additional posterior fusion in patients treated with TLIF remains uncertain. The objective of this study is to assess the clinical efficacy of circumferential fusion in patients treated with TLIF. Materials and methods: This is a single-center retrospective evaluation of consecutive 179 patients with degenerative lumbar stenosis and instability of spinal segments. Patients with axial pain and neurogenic claudication or radiculopathy associated with spinal stenosis were enrolled during the period from 2012 to 2018. Transforaminal lumbar interbody fusion (TLIF) with a single cage was used to treat patients. In 118 cases a supplementary posterior fusion was made. The duration of follow-up accounted for 24 months, logistic regression analysis was used to assess factors that influence the complication rate. Results: The rate of pedicle screw loosening was growing with radiodensity getting decreased and was more frequent in patients with two level fusion. An increase in pedicle screw loosening rate correlated with anterior nonunion Tan 2 and 3 grade while both posterior complete and incomplete fusion resulted in a decline in the complication rate. Lumbosacral fusion, bilateral facet joints` resection and laminectomy turned out to be insignificant factors. The overall goodness of fit of the estimated general multivariate model was χ2 = 87.2230; P < 0.0001. To confirm clinical relevance of those findings, a univariate logistic regression was performed to assess the association between clinically significant pedicle screw instability and posterior fusion in patients operated on employing TLIF. The results of logistic regression analysis demonstrate that additional posterior fusion may decrease the rate of instrumentation failure that requires revision surgery in patients treated with TLIF [B0 = 1.314321; B1 = -3.218279; p = 0.0023; OR = 24.98507; 95% CI (3.209265; 194.5162), the overall goodness of fit of the estimated regression was χ2 = 22.29538, p = <0.0001]. Conclusion: Circumferential fusion in patients operated on employing TLIF is associated with a decline in the rate of pedicle screw loosening detected by CT imaging and clinically significant instrumentation failure.

Biological Characteristics of Polyurethane-Based Bone-Replacement Materials.

A study is presented on four polymers of the polyurethane family, obtained using a two-stage process. The first composition is the basic polymer; the others differ from it by the presence of a variety of fillers, introduced to provide radiopacity. The fillers used were 15% bismuth oxide (Composition 2), 15% tantalum pentoxide (Composition 3), or 15% zirconium oxide (Composition 4). Using a test culture of human fibroblasts enabled the level of cytotoxicity of the compositions to be determined by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay, along with variations in the characteristics of the cells resulting from their culture directly on the specimens. The condition of cells on the surfaces of the specimens was assessed using fluorescence microscopy. It was shown that introducing 15% bismuth, tantalum, or zinc compounds as fillers produced a range of effects on the biological characteristics of the compositions. With the different fillers, the levels of toxicity differed and the cells' proliferative activity or adhesion was affected. However, in general, all the studied compositions may be considered cytocompatible in respect of their biological characteristics and are promising for further development as bases for bone-substituting materials. The results obtained also open up prospects for further investigations of polyurethane compounds.

Circumferential Fusion Employing Transforaminal vs. Direct Lateral Lumbar Interbody Fusion-A Potential Impact on Implants Stability.

Background: Different fusion techniques were introduced in clinical practice in patients with lumbar degenerative disc disease, however, no evidence has been provided on the advantages of one technique over another. The Objective of This Study: Is to assess the potential impact of circumferential fusion employing transforaminal lumbar interbody fusion (TLIF) vs. direct lateral interbody fusion (DLIF) on pedicle screw stability. Materials and Methods: This is a single-center prospective evaluation of consecutive 138 patients with degenerative instability of lumbar spinal segments. Either conventional transforaminal lumbar interbody fusion (TLIF) with posterior fusion or direct lateral interbody fusion (DLIF) using cages of standard dimensions, were applied. The conventional open technique was used to supplement TLIF with pedicle screws while percutaneous screw placement was used in patients treated with DLIF. The duration of the follow-up accounted for 24 months. Signs of pedicle screws loosening (PSL) and bone union after fusion were assessed by the results of CT imaging. Fisher's exact test was used to assess the differences in the rate of CT loosening and revision surgery because of implant instability. Logistic regression was used to assess the association between potential factors and complication rate. Results: The rate of PSL detected by CT and relevant revision surgery in groups treated with TLIF and DLIF accounted for 25 (32.9%) vs. 2 (3.2%), respectively, for the former and 9 (12.0%) vs. 0 (0%) for the latter (p < 0.0001 and p = 0.0043) respectively. According to the results of logistic regression, a decrease in radiodensity values and a greater number of levels fused were associated with a rise in PSL rate. DLIF application in patients with radiodensity below 140 HU was associated with a considerable decrease in complication rate. Unipolar or bipolar pseudoarthrosis in patients operated on with TLIF was associated with a rise in PSL rate while patients treated with DLIF tolerate delayed interbody fusion formation. In patients treated with TLIF supplementary total or partial posterior fusion resulted in a decline in PSL rate. Conclusion: Even though the supplementary posterior fusion may considerably reduce the rate of PSL in patients treated with TLIF, the application of DLIF provide greater stability resulting in a substantial decline in PSL rate and relevant revision surgery.

Potential contribution of pedicle screw design to loosening rate in patients with degenerative diseases of the lumbar spine: An observational study.

BACKGROUND: The majority of published data report the results of biomechanical tests of various design pedicle screw performance. The clinical relevance and relative contribution of screw design to instrumentation stability have been insufficiently studied. AIM: To estimate the contribution of screw design to rate of pedicle screw loosening in patients with degenerative diseases of the lumbar spine. METHODS: This study is a prospective evaluation of 175 patients with degenerative diseases and instability of the lumbar spine segments. Participants underwent spinal instrumentation employing pedicle screws with posterior only or transforaminal interbody fusion. Follow-up was for 18 mo. Patients with signs of pedicle screw loosening on computed tomography were registered; logistic regression analysis was used to identify the factors that influenced the rate of loosening. RESULTS: Parameters included in the analysis were screw geometry, type of thread, external and internal screw diameter and helical pitch, bone density in Hounsfield units, number of levels fused, instrumentation without anterior support, laminectomy, and unilateral and bilateral total facet joint resection. The rate of screw loosening decreased with the increment in outer diameter, decrease in core diameter and helical pitch. The rate of screw loosening correlated positively with the number of fused levels and decreasing bone density. Bilateral facet joint removal significantly favored pedicle screw loosening. The influence of other factors was insignificant. CONCLUSION: Screw parameters had a significant impact on the loosening rate along with bone quality characteristics, the number of levels fused and the extensiveness of decompression. The significance of the influence of screw parameters was comparable to those of patient- and surgery-related factors. Pedicle screw loosening was influenced by helical pitch, inner and outer diameter, but screw geometry and thread type were insignificant factors.

Pedicle Screws Loosening in Patients With Degenerative Diseases of the Lumbar Spine: Potential Risk Factors and Relative Contribution.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To determine risk factors that may affect the rate of pedicle screws loosening in patients with degenerative diseases of the lumbar spine. METHODS: A total of 250 patients with a low-grade spondylolisthesis and lumbar instability associated with degenerative diseases were enrolled. Preoperatively patients underwent computed tomography (CT) and cancellous bone radiodensity of a vertebral body was measured in Hounsfield units (HU). Pedicle screw fixation was used to treat patients either with a posterior fusion only or in combination with transforaminal lumbar interbody fusion (TLIF), anterior lumbar interbody fusion (ALIF), and direct lateral interbody fusion (D-LIF). Minimal follow-up period accounted for 18 months. Cases with screw loosening were registered assessing association with risk factors using logistic regression. RESULTS: The rate of screw loosening was in positive correlation with the number fused levels and decreasing bone radiodensity. Fusion with a greater load-bearing surface cage was associated with the decrease in rate of pedicle screws loosening. Incomplete reduction in case of spondylolisthesis, bilateral facet joints removal, and laminectomy performed without anterior support favored pedicle screws loosening development. The estimated model classifies correctly 79% of cases with the specificity and sensitivity accounting for 87% and 66% respectively. CONCLUSIONS: The decreasing bone radiodensity in Hounsfield units has a considerable correlation with the rate of pedicle screws loosening. On the other hand, the length of fixation and applied surgical technique including fusion type also have a significant impact on complication rate. Spinal instrumentations should be planned by taking into account all potential risk factors and not characteristics relevant to bone quality assessment alone.

The Potential Impact of Venobasillar System Morphology and Applied Technique on Epidural Cement Leakage with Percutaneous Vertebroplasty.

BACKGROUND: Bone cement leakage during vertebroplasty is a frequently reported complication with the potential for neural injury. OBJECTIVE: To assess risk factors for epidural cement leakage during vertebroplasty. SETTING: Neurosurgical department of a scientific research institute. STUDY DESIGN: This is a prospective cross-sectional randomized trial. METHODS: Seventy-five patients with intractable pain due to low energy vertebral compression fractures between T11 and L5 were treated with vertebroplasty at 150 vertebral levels. Preoperative computed tomography (CT) scans were utilized to characterize vertebral parameters including the type of nutrient foramina in the posterior vertebral cortex. Following vertebroplasty, distance from the needle tracts to the midline and the presence and type of any epidural cement leakage were determined. Using logistic regression analysis, significant risk factors for cement leakage were determined. RESULTS: A smaller distance between the tip of the needle and the midline and a magistral type of venobasillar system were found to be significant risk factors for epidural cement leakage (P < 0.0001). Use of a bipedicular vs. monopedicular technique did not significantly affect the rate of epidural cement leakage (P = 0.3869). LIMITATIONS: This study is limited because of the relatively small number of patients and the lack of any patients who had clinical consequences as a result of extensive epidural cement leakage. CONCLUSION: The type of venobasillar system should be taken into account when planning a vertebroplasty procedure as a magistral type of venobasillar system is associated with the increased rate of epidural cement leakage. It is important to try and achieve a large distance between the needle tip and the midline, especially when a magistral type of venobasillar system is present, to reduce the risk of epidural cement leakage.

The potential impact of various diagnostic strategies in cases of chronic pain syndromes associated with lumbar spine degeneration.

PURPOSE: To study the possible effects of various diagnostic strategies and the relative contribution of various structures in order to determine the optimal diagnostic strategy in treating patients with noncompressive pain syndromes. STUDY DESIGN: Prospective, nonrandomized cohort study of 83 consecutive patients with noncompressive pain syndromes resistant to repeated courses of conservative treatment. The follow-up period was 18 months. RESULTS: Nucleoplasty was effective in cases of discogenic pain; the consequences related to false positive results of the discography were significant. The most specific criterion was 80% pain relief after facet joint blocks, whereas 50% pain relief and any subjective pain relief were not associated with a significant increase in the success rate. A considerable rate of false negative results was associated with 80% pain relief, whereas 50% pain relief after facet joint blocks showed the optimal ratio of sensitivity and specificity. Facet joint pain was detected in 50.6% of cases (95% confidence interval 44.1%-66.3%), discogenic pain in 16.9% cases (95% confidence interval 9.5%-26.7%), and sacroiliac joint pain in 7.2% cases (95% confidence interval 2.7%-15%). It was impossible to differentiate the main source of pain in 25.3% of cases. CONCLUSION: It is rational to adjust the diagnostic algorithm to the probability of detecting a particular pain source and, in doing so, reduce the number of invasive diagnostic measures to evaluate a pain source. False positive results of diagnostic measures can negatively affect the overall efficacy of a particular technology; therefore, all reasons for the failure should be studied in order to reach an unbiased conclusion. In choosing diagnostic criteria, not only should the success rate of a particular technology be taken into consideration but also the rate of false negative results. Acceptable diagnostic criteria should be based on a rational balance of sensitivity and specificity.

An analysis of reasons for failed back surgery syndrome and partial results after different types of surgical lumbar nerve root decompression.

BACKGROUND: Despite the evident progress in treating vertebral column degenerative diseases, the rate of a so-called "failed back surgery syndrome" associated with pain and disability remains relatively high. However, this term has an imprecise definition and includes several different morbid conditions following spinal surgery, not all of which directly illustrate the efficacy of the applied technology; furthermore, some of them could even be irrelevant. OBJECTIVE: To evaluate and systematize the reasons for persistent pain syndromes following surgical nerve root decompression. STUDY DESIGN: Prospective, nonrandomized, cohort study of 138 consecutive patients with radicular pain syndromes, associated with nerve root compression caused by lumbar disc herniation, and resistant to conservative therapy for at least one month. The minimal period of follow-up was 18 months. SETTING: Hospital outpatient department, Russian Federation METHODS: Pre-operatively, patients were examined clinically, applying the visual analog scale (VAS), Oswestry Disability Index (ODI), magnetic resonance imaging (MRI), discography and computed tomography (CT). According to the disc herniation morphology and applied type of surgery, all participants were divided into the following groups: for those with disc extrusion or sequester, microdiscectomy was applied (n = 65); for those with disc protrusion, nucleoplasty was applied (n = 46); for those with disc extrusion, nucleoplasty was applied (n = 27). After surgery, participants were examined clinically and the VAS and ODI were applied. All those with permanent or temporary pain syndromes were examined applying MRI imaging, functional roentgenograms, and, to validate the cause of pain syndromes, different types of blocks were applied (facet joint blocks, paravertebral muscular blocks, transforaminal and caudal epidural blocks). RESULTS: Group 1 showed a considerable rate of pain syndromes related to tissue damage during the intervention; the rates of radicular pain caused by epidural scar and myofascial pain were 12.3% and 26.1% respectively. Facet joint pain was found in 23.1% of the cases. Group 2 showed a significant rate of facet joint pain (16.9%) despite the minimally invasive intervention. The specificity of Group 3 was the very high rate of unresolved or recurred nerve root compression (63.0%); in other words, in the majority of cases, the aim of the intervention was not achieved. The results of the applied intervention were considered clinically significant if 50% pain relief on the VAS and a 40% decrease in the ODI were achieved. LIMITATIONS: This study is limited because of the loss of participants to follow-up and because it is nonrandomized; also it could be criticized because the dynamics of numeric scores were not provided. CONCLUSION: The results of our study show that an analysis of the reasons for failures and partial effects of applied interventions for nerve root decompression may help to understand better the efficacy of the interventions and could be helpful in improving surgical strategies, otherwise the validity of the conclusion could be limited because not all sources of residual pain illustrate the applied technology efficacy. In the majority of cases, the cause of the residual or recurrent pain can be identified, and this may open new possibilities to improve the condition of patients presenting with failed back surgery syndrome.

Differential treatment of nerve root compression pain caused by lumbar disc herniation applying nucleoplasty.

BACKGROUND: Nucleoplasty is a minimally invasive intervention use to perform disc decompression in cases of nerve root compression caused by disc herniation. It is important to find rational guidelines for choosing between nucleoplasty and microsurgery. OBJECTIVE: To analyze factors that may impact the results of nucleoplasty, and to validate the rational guidelines between minimally invasive treatment and open surgery. STUDY DESIGN: Prospective, non-randomized, cohort study with a minimal follow-up period of 18 months. METHODS: Patients were given a neurological examination, visual analogue scale and Oswestry disability questionnaire, obligatory MRI, optional RCT, and discography, only before nucleoplasty. Patients have been divided into the following groups: Group 1 - patients with a disc protrusion treated with nucleoplasty (n = 46), which has been divided into Subgroup 1A, those with a disc protrusion size ≤ 5 mm (n = 24), and Subgroup 1B, those with a disc protrusion size 6 - 9 mm (n = 22); Group 2 - patients with a disc extrusion treated with nucleoplasty (n = 27); Group 3 - patients with a disc extrusion or sequester treated with microdiscectomy (n = 65). OUTCOME MEASURES: Clinically significant outcomes were a 50% relief of pain intensity and a 40% decrease of Oswestry Disability Index (ODI). RESULTS: A decrease of pain intensity and disability was found in all groups of patients, P < 0.0001; SP (statistical power) = 99 - 100%. Subgroups 1A and 1B showed no clinically significant differences in outcome, P = 0.99; SP = 5.3. Clinically significant results: Group 1 - 78%; 95% CI (confidence interval) [66; 90%], Group 2 - 44%; 95% CI [25; 65%], Group 3 - 93%; 95% CI [85; 98%]. Total annulus disruption increases the rate of unsatisfactory results of nucleoplasty, OR (odds ratio) = 4.5; 95% CI [1.57; 12.87] (logistic regression model, P = 0.0034). Nucleoplasty performed in cases of uncontained disc herniation (disc extrusion) have a significantly higher rate of unsatisfactory results versus microdiscectomy, OR = 19.06; 95% CI [2.29; 68.73] (logistic regression model, P < 0.0001). LIMITATIONS: This study was limited by the small number of patients in each group. CONCLUSION: The size of the disc protrusion does not significantly affect the outcome of nucleoplasty. The rational guideline for choosing between the 2 types of surgery is the integrity of the annulus.