Serum titanium, niobium, and aluminum levels after instrumented spinal arthrodesis in children

Elevated blood metal ion levels in patients undergoing instrumented spinal surgery: a systematic review and meta-analysis

BACKGROUND CONTEXT

Elevated blood metal levels have been reported in patients after spinal surgery using metallic implants. Although some studies have suggested an association between heightened blood metal concentrations and potential adverse effects, estimates of the incidence of abnormal metal levels after spinal surgery have been inconsistent.

PURPOSE

The aims of this systematic review and meta-analysis were to assess: (1) mean differences in blood metal ion levels between patients undergoing spinal fusion surgery and healthy controls, (2) odds of elevated blood metal ion levels after surgery compared to presurgery levels, and (3) pooled incidence of elevated blood metal ions overall and by metal type.

STUDY DESIGN

Systematic review and meta-analysis.

PATIENTS SAMPLE

The patient sample included 613 patients from 11 studies who underwent spinal surgery instrumentation.

OUTCOME MEASURES

Blood metal ion concentrations and the incidence of patients with elevated metal levels compared with in those the control group.

METHODS

A comprehensive search was conducted in PubMed, EMBASE, Scopus, and Cochrane Library to identify studies reporting blood metal ion levels after spinal fusion surgery. Mean differences (MD), odds ratios (OR), and incidence rates were pooled using random effects models. Heterogeneity was assessed using I2 statistics, and fixed-effects models were used if no heterogeneity was detected. Detailed statistical analysis was performed using the Review Manager version 5.4 software.

RESULTS

The analysis included 11 studies, with a total of 613 patients. Mean blood metal ion levels were significantly higher after spinal fusion surgery (MD 0.56, 95% CI 0.17-0.96; I2=86%). Specifically, titanium levels were significantly elevated (MD 0.81, 95% CI 0.32-1.30; I2=47%). The odds of elevated blood metal ions were higher after surgery (OR 8.17, 95% CI 3.38-19.72; I2=41%), primarily driven by chromium (OR 23.50, 95% CI 5.56-99.31; I2=30%). The incidence of elevated chromium levels was found to be 66.98% (95% CI 42.31-91.65).

CONCLUSION

In conclusion, blood metal ion levels, particularly titanium and chromium, were significantly increased after spinal fusion surgery compared to presurgery levels and healthy controls. Approximately 70% of the patients exhibited elevated blood levels of chromium and titanium.

Serum Titanium Levels Remain Elevated But Urine Titanium is Undetectable in Children With Early Onset Scoliosis Undergoing Growth-Friendly Surgical Treatment: A Prospective Study

BACKGROUND

Elevated serum titanium levels have been found in patients with early onset scoliosis (EOS) treated with traditional growing rods (TGR), magnetically controlled growing rods (MCGR), and vertical expandable prosthetic titanium rib (VEPTR). No studies have investigated whether serum titanium remains persistently elevated and if titanium is excreted. Our purpose was to compare serum titanium levels in patients with EOS with growth-friendly instrumentation to age-matched controls and evaluate urine titanium and serial serum titanium levels in patients with EOS.

METHODS

This was a prospective case-control study. Patients with EOS with TGR, MCGR, or VEPTR underwent urine titanium and serial serum titanium collection at a minimum 6-month interval. Control patients did not have a history of metal implant insertion and underwent serum titanium collection before fracture fixation.

RESULTS

Twenty patients with EOS (6 TGR, 8 MCGR, and 6 VEPTR) and 12 controls were analyzed. The control group had no detectable serum titanium (0 ng/mL), whereas the patients with EOS had a median serum titanium of 4.0 ng/mL ( P < 0.001). Analysis of variance showed significantly higher median serum titanium levels in the MCGR and VEPTR groups than the TGR group at time point 1 (5.5 vs 6.0 vs 2.0 ng/mL, P = 0.01) and time point 2 (6.5 vs 7.5 vs 2.0 ng/mL, P < 0.001). Binary comparisons showed a significant difference in serum titanium level between TGR and MCGR (time point 1: P = 0.026, time point 2: P = 0.011) and TGR and VEPTR (time point 1: P = 0.035, time point 2: P = 0.003). However, there was no difference between MCGR and VEPTR (time point 1: P = 0.399, time point 2: P = 0.492) even though the VEPTR group had a longer duration of follow-up ( P = 0.001) and a greater number of lengthenings per patient at the first serum collection ( P = 0.016). No patients with EOS had detectable urine titanium.

CONCLUSIONS

Patients with EOS treated with titanium alloy growth-friendly instrumentation had elevated serum titanium levels compared with age-matched controls that persisted over time with no evidence of renal excretion. Additional studies are necessary to assess for local and systemic accumulation of titanium and the significance of long-term exposure to titanium in growing children.

LEVEL OF EVIDENCE

Level III, therapeutic.

Persistently Raised Serum Titanium Levels After Spinal Instrumentation in Children

STUDY DESIGN

Prospective study of patients undergoing elective spinal deformity surgery with repeated testing for circulating metal ions including preoperative levels acting as controls.

OBJECTIVE

The aim was to determine if levels of particular circulating metal ions are maintained to two years postsurgery including different implant systems and rods.

SUMMARY OF BACKGROUND DATA

Adults having hip replacements, especially metal-on-metal bearings, may develop high metal ion levels. Pediatric spinal implants are known to cause circulating metal ions, notably titanium, chromium, cobalt, and nickel.

MATERIALS AND METHODS

Fifty-six children having spinal deformity surgery were studied with repeated testing for circulating metal ions, using high-resolution inductively coupled plasma mass spectrometry. Linear mixed-effects models adjusting for repeated measurements over time were used to analyze levels of titanium, cobalt, chromium, and nickel.

RESULTS

Titanium levels showed a rapid increase by seven days and a peak at 30 days that was essentially maintained at the two-year assay. At two years, titanium levels were 5.14 times greater compared with the presurgery control level (P<0.0001). Cobalt levels were shown to gradually rise to a peak at 30 days and then slowly decline but remained 1.74 times above mean baseline level at two years (P=0.0004), with a declining trajectory. Chromium and nickel levels rose immediately postoperatively and then steadily declined to baseline by six months and remained at baseline at two years. The five implant systems tested had generally equivalent results.

CONCLUSION

The persistent and rising levels of titanium, in a predominantly female population, is concerning. Titanium is known to cross the placental barrier and enter the circulation of the fetus in rodents and humans, and to accumulate in solid organs especially the liver, spleen, heart, and lymph nodes in humans. This potentially exposes the offspring of mothers with spinal implants to titanium, with potential teratogenic effects.

Comparison of Different Surgical Systems for Treatment of Early-onset Scoliosis in the Context of Release of Titanium Ions

STUDY DESIGN

Case-control study.

OBJECTIVE

The aim of the study was to compare growth-friendly systems: traditional growing rod, guided growth systems (GGS), and vertical expandable prosthetic titanium rib in the context of titanium release.

SUMMARY OF BACKGROUND DATA

The problem of scoliosis affects even up to 3% of the population, and ca. 0.1% of patients need surgical treatment. Surgical treatment carries the risk of a long-term presence of implants in the organism, which may result in release of metal ions into the tissues and bloodstream.

METHODS

Seventy-one patients (13.5 ± 3.54 years' old) were treated for spinal deformity using various surgical systems and the samples of paraspinal tissue, blood, nails, and hair were collected before and after treatment. The quantification of titanium was performed using inductively coupled plasma optical emission spectrometry.

RESULTS

The metallic particles were released into the peri-implant tissue, and the greatest amounts of titanium were detected in patients with GGS. The concentration of soluble titanium forms in subcutaneous tissue (ST) was low and do not statistically differ from control. The average titanium content in the paraspinal tissue in patients with GGS was two- to three-fold higher than the average value in the other investigated groups. A slightly increased level of titanium compared with the control was noted in all studied groups of patients. The highest content of titanium in blood was observed in patients with the GGS system.

CONCLUSION

Neverless the system used, the concentration of soluble titanium forms in both ST and blood was only slightly higher than in the control and did not exceed the allowable levels. The increased level of titanium with GGS system is probably associated with the friction between implant components, whereas the components in the other systems are immobile relative to each other.Level of Evidence: 3.

Evaluation of titanium release from titanium alloy implants in patients with spinal instrumentation

Objective

This study was performed to investigate the baseline serum titanium levels in patients with short-segment titanium alloy posterior instrumentation and to assess patient-, implant-, and surgery-related factors that might affect the serum titanium level.

Method

Two groups of patients were included in the study. The study group comprised 39 patients who had undergone short-segment posterior instrumentation from January 2013 to June 2016. The control group comprised 11 randomly selected patients who presented to the outpatient clinic with no history of orthopedic surgery. The serum titanium levels and inter-group differences were analyzed.

Results

The mean serum titanium level was significantly higher in the study group than in the control group. No significant difference was observed between patients with different etiologies, implants used for fusion, numbers of instrumented segments, or postoperative durations.

Conclusion

The serum titanium levels of patients with posterior lumbar spinal instrumentation are significantly higher than those of the normal population even after achievement of solid fusion. These levels are not affected by the use of transverse connectors, the use of cages, the operated segments, or the duration of implants.

Understanding the implant performance of magnetically controlled growing spine rods: a review article

PURPOSE

Early-Onset Scoliosis (EOS) (defined as a curvature of the spine ≥ 10° with onset before 10 years of age) if not properly treated, can lead to increased morbidity and mortality. Traditionally Growing Rods (TGRs), implants fixated to the spine and extended every 6-8 months by surgery, are considered the gold standard, but Magnetically Controlled Growing Rods (MCGRs) avoid multiple surgeries. While the potential benefit of outpatient distraction procedure with MCGR is huge, concerns still remain about its risks, up to the release of a Medical Device Alert (MDA) by the Medicines and Healthcare Regulatory Agency (MHRA) advising not to implant MCGRs until further notice. The aim of this literature review is to (1) give an overview on the use of MCGRs and (2) identify what is currently understood about the surgical, implant and patient factors associated with the use of MCGRs.

METHODS

Systematic literature review.

RESULTS

Surgical factors such as use of single rod configuration or incorrect rod contouring might affect early failure of MCGRs. Patient's older age and higher BMI are correlated with rod slippage. Wear debris and distraction mechanism failure may result from implant design and iteration.

CONCLUSION

Despite the complications reported, this technology still offers one of the best solutions to spine surgeons dealing with severe EOS. Lowering the complication rate by identifying risk factors for failure is possible and further studies in this direction are required. Once the risk factors are well described, some of these can be addressed enabling a safer use of MCGRs.

Analysis of serum levels of titanium and aluminium ions in patients with early onset scoliosis operated upon using the magnetic growing rod-a single centre study of 14 patients

STUDY DESIGN

A cross-sectional retrospective Level 3 study.

OBJECTIVE

To study the serum levels of Titanium and Aluminium ions in patients operated using the magnetically controlled growing rod (MCGR) system. 14 consecutive patients of early onset scoliosis with varying etiology managed with MCGR system with a minimum follow-up of 24 months were selected for the study. The group consisted of two boys (14.3%) and 12 girls (85.7%). The average age of the patients at the time of surgery was 10.4 years (5-15 years). The average period of follow-up was 43.7 months (28-79 months). After informed consent of the subjects and their caretakers, serum levels of titanium and aluminium were measured. These levels were then assessed with regards to the number of screws used, number of distractions and complications.

METHODS

The concentration of titanium and aluminium ions in the serum was measured using high resolution inductively coupled plasma mass spectrometry.

RESULTS

For the sake of ease of assessment, patients were divided into three etiology-based groups-idiopathic (n = 6), neuromuscular (n = 2) and syndromic (n = 6). The mean serum titanium level was 15.9 μg/L (5.1-28.2 μg/L) while that of aluminium was 0.1 μmol/L (0.1-0.2 μmol/L). Of the 14 patients, 2 (14.2%) patients had mechanical failure (actuator pin dysfunction), 3 (21.4%) had rod breakage requiring revision surgery and one patient (7.1%) had surgical site infection managed with appropriate antibiotics. Patients undergoing revision for rod breakage did not show any metallosis of the tissues during surgery.

CONCLUSION

Analysis of patients with scoliosis operated using the magnetic growing rod system concludes that it is accompanied by presence of titanium in the blood but whether clinically significant or not needs to be ascertained by comparison of preoperative and postoperative blood concentrations of the titanium ions in individual subjects. The aluminium ion concentration remains within normal limits. Though implant malfunction may raise the titanium levels in the blood, its clinical significance needs to be determined. The aluminium levels are not affected irrespective to the presence or absence of complications. The long-term effects of raised titanium levels in the blood also warrant further prospective studies designed for precise and deeper analyses.

A systematic review of metal ion concentrations following instrumented spinal fusion

PURPOSE

Metallic spinal implants undergo wear and corrosion which liberates ionic or particulate metal debris. The purpose of this study was to identify and review studies that report the concentration of metal ions following multi-level spinal fusion and to evaluate the impact on clinical outcomes.

METHODS

Databases (PubMed, EBSCO MEDLINE) were searched up to August 2019 for studies in English-language assessing metal ion levels [chromium (Cr), titanium (Ti), nickel (Ni)] in whole blood, serum, or plasma after spinal fusion using a specific search string. Study, patient, and implant characteristics, method of analysis, metal ion concentration, as well as clinical and radiographic results was extracted.

RESULTS

The systematic search yielded 18 studies encompassing 653 patients. 9 studies reported Ti ions, eight reported Cr, and six reported Ni. Ti levels were elevated compared to controls/reference range/preoperative baseline in seven studies with the other two reporting no difference. Cr levels were elevated compared to controls/reference range in seven studies with one reporting no difference. Ni levels showed no difference from controls/reference range in four studies with one reporting above normal and another elevated compared to controls. Radiographic evidence of corrosion, implant failure, pseudarthrosis, revision surgery and adverse reaction reporting was highly variable.

CONCLUSION

Metal ions are elevated after instrumented spinal fusion; notably Cr levels from stainless steel implants and Ti from titanium implants. The association between clinical and radiographic outcomes remain uncertain but is concerning. Further research with standardized reporting over longer follow-up periods is indicated to evaluate the clinical impact and minimizing risk.

Chromium Metal Ion Release During Instrumented Spinal Surgery in Children: The Effects of Electrosurgery

STUDY DESIGN

Prospective 2-year study with operative sampling and in-vitro analysis of chromium ions following spinal surgery in children.

OBJECTIVES

To measure metal ion levels at preoperative, intraoperative, and postoperative times to determine patterns of metal ion release during instrumented spinal surgery.

SUMMARY OF BACKGROUND DATA

Raised serum metal ion levels are reported following instrumented spinal fusion in adolescent idiopathic scoliosis. The authors noted raised chromium levels in patients receiving implants that did not contain chromium. This prompted further work to establish the source. The electrosurgery tips used were discovered to contain 17% chromium.

METHODS

Chromium, cobalt, and titanium levels were measured before, during, and after surgery in serum and local intraoperative fluid samples in 11 children undergoing posterior instrumentation for scoliosis. Administered drugs, cell-saver fluids, and intraoperative fluids, both local and intravenous, were investigated to exclude these as sources of chromium ions. An in-vitro study was also performed to elucidate sources of intraoperative chromium ions.

RESULTS

High chromium levels were detected in all samples from the wound irrigation fluid prior to insertion of metal implants. Immediate postoperative chromium serum ion levels were also elevated and returned to baseline by day 30. In-vitro sampling of fluids from test models using electrosurgery revealed high levels of chromium ions CONCLUSION.: This finding of high chromium metal ion concentrations in intraoperative and early postoperative samples provides evidence of chromium release during the dissection phase of spinal surgery. This challenges existing beliefs that metal ion release occurs solely due to implants and now implicates the electrosurgery electrode tips as a source of raised chromium ion levels. Thorough irrigation of the operative site after the dissection phase of surgery to both dilute and reduce the intraoperative chromium ion load is suggested. Alternative electrosurgery electrode tips or other methods to coagulate during surgery could be considered.

LEVEL OF EVIDENCE

2.

Do Children With Spinal Deformity Who Have Metal Implants and Frequent Exposure to X-Rays Increase Their Risk of Cancer?

STUDY DESIGN

Spinal surgery cohort.

OBJECTIVE

The authors assess the risk of cancer in children who have undergone frequent radiographs and have metal implants for the treatment of spinal deformity.

SUMMARY OF BACKGROUND DATA

Concerns have been raised regarding the cancer risk to children exposed to repeated radiological examinations as part of routine surveillance to monitor progression of spinal deformity. Additionally, there are reports of increased cancer risk in adults having joint replacement with metal implants causing raised metal ion levels in the blood.

METHODS

A large number of consecutive children undergoing instrumented spinal surgery since 1979 were examined for their development of malignancy. High quality data on all invasive cancers from the South Australian Cancer Registry and deaths were linked to the spinal surgery cohort with the calculation of standardized incidence ratios (SIRs) using the Quinquinquennium method.

RESULTS

The study cohort was formed by 865 children. The average follow-up time from date of surgery to either death or censoring date was 18 years with a maximum of 36 years. A total of 15,921 person years were examined. There was no increased rate of cancer in these patients. For the total cohort, the SIR was 1.00 (95% confidence interval [CI] 0.50-1.79). For females the SIR was 0.83 (95% CI 0.33-1.70) and for males the SIR was 1.33 (95% CI 0.36-3.40). The male SIR reflected an expected cancer incidence of three cases, when four cases were observed, and was not statistically significant.

CONCLUSION

This study has found that radiation exposure and possible exposure to circulating metal ions as a result of routine instrumented spine surgery in children since 1979 is not associated with an increased risk of cancer in up to 36 years of follow up.

LEVEL OF EVIDENCE

2.

Challenges in the Measurement and Interpretation of Serum Titanium Concentrations

The measurement of circulating metal ion levels in total hip arthroplasty patients continues to be an area of clinical interest. National regulatory agencies have recommended measurement of circulating cobalt and chromium concentrations in metal-on-metal bearing symptomatic total hip arthroplasty patients. However, the clinical utility of serum titanium (Ti) measurements is less understood due to wide variations in reported values and methodology. Fine-scale instrumentation for detecting in situ Ti levels continues to improve and has transitioned from graphite furnace atomic absorption spectroscopy to inductively coupled plasma optical emission spectrometry or inductively coupled plasma mass spectrometry. Additionally, analytical interferences, variable sample types, and non-standardized sample collection methods complicate Ti measurement and underlie the wide variation in reported levels. Normal reference ranges and pathologic ranges for Ti levels remain to be established quantitatively. However, before these ranges can be recognized and implemented, methodological standardization is necessary. This paper aims to provide background and recommendations regarding the complexities of measurement and interpretation of circulating Ti levels in total hip arthroplasty patients.

Titanium Alloy Intramedullary Nails and Plates Affect Serum Metal Ion Levels within the Fracture Healing Period

Titanium alloy implants are the most used materials for the fixation of lower extremity fractures. Although these implants were thought to be inert materials in vitro, several studies have shown increased serum and remote tissue metal ion levels due to wear of implants and friction of the bone-implant interface in vivo. The aim of this study was to investigate the alteration of serum metal ion levels that are released from intramedullary nails and plates used for the fixation of lower extremity fractures, within the fracture healing period. The study included 20 adult patients, who were treated with intramedullary nail or plate osteosynthesis due to closed lower extremity fractures. Alterations of serum titanium, aluminum, molybdenum, and vanadium levels were evaluated at 6, 12, 18, and 24 weeks postoperatively. A statistically significant increase was determined in serum titanium, aluminum, molybdenum, and vanadium ion levels in the intramedullary nail and plate groups at the end of the follow-up period. Pairwise comparisons of metal ion levels between implant groups revealed no significant difference during a 24-week follow-up period. Compared to the control group, statistically significant increased levels of serum titanium, aluminum, vanadium, and molybdenum ions were determined in the implant groups used for the fixation of lower extremity fractures at the end of 24 weeks. In the current literature, the potential toxic effects of prolonged exposure to low levels of these metal ions are still unknown. It can be predicted that long-term metal ion exposure could result in vivo pathological processes in the future.

Elevated Serum Titanium Levels in Children With Early Onset Scoliosis Treated With Growth-friendly Instrumentation

BACKGROUND

A previous study showed significantly higher serum titanium levels in patients with early-onset scoliosis (EOS) treated with traditional growing rods (TGR) and magnetically controlled growing rods (MCGR) compared with controls. Children with vertical expandable prosthetic titanium rib (VEPTR) were not assessed. The purpose of this study was to compare serum titanium levels in EOS patients treated with TGR, MCGR, and VEPTR. We hypothesized that EOS patients treated with all forms of growth-friendly instrumentation (GFI) have elevated serum titanium levels.

METHODS

This was a prospective cross-sectional case series. Serum titanium levels were collected from patients with GFI who were enrolled in an EOS database. Blood samples were collected at a clinic visit or lengthening/exchange procedure between April and December 2018. The normal range for serum titanium is 0 to 1 ng/mL. Analyses were conducted using analysis of variance and Bonferroni post hoc test.

RESULTS

A total of 23 patients (2 TGR, 8 MCGR, 13 VEPTR) were analyzed. There was a significant difference in age at the time of blood sample collection (12.5 vs. 9.8 vs. 7.5 y, P=0.015) and serum titanium level (1.5 vs. 4.5 vs. 7.6 ng/mL, P=0.021) between TGR, MCGR, and VEPTR, respectively. All of the MCGR and VEPTR patients had a serum titanium level ≥2 ng/mL. Binary comparisons showed that VEPTR had a significantly higher serum titanium level than TGR (P=0.046). There was no difference in serum titanium level when MCGR was compared with TGR and VEPTR. Time from implant insertion to blood sample collection, number of rods currently implanted, total number of rods implanted throughout treatment, and number of lengthenings per patient was similar between the groups.

CONCLUSIONS

Elevated serum titanium levels may be present in EOS patients treated with all forms of GFI. Although our TGR patients had indwelling implants for the longest period of time, they had the lowest serum titanium level. Repetitive chest wall motion during respiration may lead to continued wear and metal ion release with VEPTR.

LEVEL OF EVIDENCE

Level II-therapeutic.

Evaluation of Titanium Serum Levels in Patients After Spine Instrumentation: Comparison Between Posterolateral and 360º Spinal Fusion Surgery

Introduction

The use of orthopedic implants is a cause for concern for the release of its integrating metals and the systemic complications that may occur. Instrumented spine arthrodesis is the recommended treatment for many spine diseases. Different segmental fixation devices, commonly made of titanium and its alloys, are used in these surgeries. The use of this metal for spinal fusion has introduced the possibility of generating microscopic metal particles that are present in the tissues of the surrounding implants (peri-implant environment). In fact, metal debris has been found in the paraspinal soft tissues of patients with posterior lumbar instrumentation and showed to be particularly high in patients undergoing revision procedures of pseudoarthrosis. In addition, part of the metals might also dissolve (either from the released particles or directly from the implant surface) and circulate in the body fluids, accumulating (eventually) in remote organs.

Material and methods

A prospective study was designed with patients who were to be operated by the pathology of the lumbar spine to perform a vertebral arthrodesis composed of a titanium alloy (n=32). Two subgroups were differentiated according to the type of surgery performed: a) Posterolateral arthrodesis (N=5); b) Circumferential arthrodesis intervertebral implant of polyester-ether ketone (PEEK) (N=8) or titanium (N=19). The blood sample was taken before surgery and one year later. The samples were analyzed by mass spectrophotometry with a double focus inductive coupling plasma source (DF-ICP-MS).

Results

Blood titanium levels prior to surgery were similar to those in other publications (0.7449 micrograms per liter^-1 (µgL^-1), Standard Deviation (SD)=0.562). The average titanium concentration levels found after surgery was 2.5406 µgL^-1 (SD=3,69), near 3.5-fold increase. After surgery, there was a significant mean increase in serum titanium levels of 1.7957 µgL^-1 (SD=3.5765, Range=-0.57 µgL^-1; 14.60 µgL^-1). There is a statistically significant increment (p=0.00049) of the titanium concentration in the serum of the patients after surgery. If we analyze the patients in three groups according to the type of implants used (posterolateral, circumferential with PEEK, and circumferential with titanium), there are no differences between those who did not have an intersomatic device implanted and those in which PEEK implants were implanted, but with those in which it was titanium it was p=0.006 and p=0.018, respectively.

Conclusions

Patients undergoing vertebral instrumentation experience a significant increase in serum titanium levels compared to before surgery levels. The use of an intersomatic device did not show differences in titanium release with not using it when it was PEEK. There are significant differences between patients without intersomatic implants or those who had a PEEK implant with those in whom it was titanium, with a significant increase in blood titanium levels.

Pattern of blood concentrations of 47 elements in two populations from the same geographical area but with different geological origin and lifestyles: Canary Islands (Spain) vs. Morocco

The Canary Islands are one of the outermost regions of the European Union (EU), which are located barely 100 km from the coasts of Morocco. Although these islands are located in Africa, the degree of socioeconomic development and lifestyle in this archipelago is comparable to that of any other region of Europe. It is well established that the main determinants of human exposure to elements have to do both, with their place of residence and with habits related to their lifestyle. For this reason, we wanted to study the pattern of contamination by elements of these two populations so geographically close, but so different both in their lifestyle, and the geological origin of the territory where they live. Thus, we have determined the blood concentrations of 47 elements (including 25 rare earth elements (REE) and other minority elements (ME) widely employed in the hi-tech industry) in a paired sample of Moroccans (n = 124) and Canary Islands inhabitants (n = 120). We found that the levels of iron, selenium, zinc, arsenic, cadmium, strontium, and specially lead, were significantly higher in Moroccans than in Canarians, probably due to the intensive mining activity in this country. We also found significantly higher levels of the sum of REE and ME in Moroccans than in Canarians, possibly related to the inappropriate management of e-waste in this country. On the other hand, in the inhabitants of the Canary Islands we found higher levels of manganese, probably related to a higher degree of exposure to heavy traffic and exposure to Saharan dust of the people living in this region, and niobium and bismuth, probably related to the higher economic development in these islands. Our results indicate that the vicinity of both territories is not a major determinant of each other's contamination.

Evaluation of Blood Titanium Levels and Total Bone Contact Area of Dental Implants

The purpose of this study was to evaluate the effect of total implant-bone surface contact area of dental implants applied on partial or total edentulous patients on the increase in the level of blood titanium level. Changes of the blood titanium levels were evaluated after placement of the dental implants in 30 patients including 15 females and 15 males. Patients were divided into 3 groups as dental implants were applied on only maxilla, only mandible, or both of them. Taking into the consideration anatomic formation and prosthetic indication, dental implant-bone total contact area was calculated and saved for each patient after dental implants placement. Blood samples of the patients taken preoperatively and postoperatively at 12 weeks were analyzed by ICP-MS device. Blood titanium levels of preoperative and postoperative blood samples were analyzed for each patient and results were evaluated statistically. In the evaluation after analyzing blood titanium level changes, while a statistically significant decrease was observed in Group 1 patients, a statistically significant increase was observed in Group 2 and Group 3 patients to blood titanium level. A statistically significant difference was observed between Group 1 and Group 2 and between Group 1 and Group 3 patients of blood titanium levels. The change of the blood titanium level was not related to total implant-bone surface area, number of the implants, and gender. In our study, no correlation was found between change of blood titanium level and total contact area with bone of dental implants. We believe that more accurate results can be obtained with biopsy of tissues and organs on animal studies.

Analysis of soluble or titanium dioxide derived titanium levels in human whole blood: consensus from an inter-laboratory comparison

Exposure to titanium (Ti),viathe ingestion of pigment grade Ti dioxide (TiO₂), is commonplace for westernised populations.

Metal Ion Release During Growth-Friendly Instrumentation for Early-Onset Scoliosis: A Preliminary Study

BACKGROUND

Metal ions released from spinal instruments can cause localized debris and distribute systemically to settle on distant organs. Children with early-onset deformities live with metallic implants for a substantial amount of time. No research focused on metal distribution in growth-friendly instrumentations. The aim of this study was to compare age-matched growing rod (GR) and magnetically controlled growing rod (MCGR) groups to noninstrumented controls.

METHODS

The study was designed as a multicenter, prospective, cross-sectional case series. GR and MCGR applications of three institutions were included. A total of 52 children were enrolled. Blood samples were collected between December 2014 and February 2015. Biochemical serum analyses were performed to trace and quantify titanium, vanadium, aluminum, and boron. The GR group included 15 children. Mean age was 10.7 (range 6-15). MCGR group included 22 children. Mean age was 8.5 (range 2-13). Fifteen age-matched nonoperated children formed the control group. The mean age was 10.4 (range 5-15). One-way analysis of variance, Kruskal-Wallis, and Mann-Whitney U tests were used for comparisons.

RESULTS

The mean serum titanium level in control, GR, and MCGR groups were 2.8 ± 1.4, 7.3 ± 4.3, and 10.2 ± 6.8 μg/L, respectively. GR and MCGR group titanium levels were higher than controls' (p = .008 and p < .001). The mean serum vanadium level in control, GR, and MCGR groups were 0.2 ± 0.0, 0.2 ± 0.0, and 0.5 ± 0.5 μg/L, respectively. MCGR group vanadium level was higher than control (p < .001) and GR groups (p = .004). Mean serum levels in control, GR, and MCGR groups were, respectively, 5.4 ± 4.1, 8.1 ± 7.4, and 7.8 ± 5.1 μg/L for aluminum and 86.7 ± 2.7, 86.9 ± 2.5, and 85.0 ± 6.6 μg/L for boron. The distribution of aluminum and boron were similar across groups (p = .675 and p = .396).

CONCLUSIONS

Both GR and MCGR applications significantly release titanium and possibly aluminum. MCGR further releases vanadium. MCGR possibly releases more titanium than traditional GR. Time-dependent alterations of serum ion levels, structural properties of the MCGR device, and exposure caused by magnetic distraction processes warrant investigation.

A randomized double-blinded clinical trial to evaluate the safety and efficacy of a novel superelastic nickel-titanium spinal rod in adolescent idiopathic scoliosis: 5-year follow-up

PURPOSE

To evaluate the safety and efficacy of a superelastic shape-memory alloy (SNT) rod used in the treatment of adolescent idiopathic scoliosis (AIS).

METHODS

AIS Patients with Lenke 1 curves undergoing fusion surgery were randomized (1:1) at the time of surgery to receive either the SNT or a conventional titanium alloy (CTA) rod. Radiographs were obtained preoperatively and postoperatively up to 5 years of follow-up. Parameters assessed included coronal and sagittal Cobb angles, and overall truncal and shoulder balance. Sagittal profiles were subcategorized into Types A (<20°), B (20-40°), and C (>40°).

RESULTS

Twenty-four patients with mean age of 15 years were recruited. A total of 87.0% of subjects were followed up till postoperative 5 years, but all patients had minimum 2 years of follow-up. The fulcrum-bending correction index for the SNT group was 113% at postoperative day 4 and 127% at half-year, while the CTA group was 112% at postoperative day 4 and only 106% at half-year. In terms of sagittal profile, the SNT group moved toward type B profile at half-year follow-up with a mean correction of 7.6°, while no significant change was observed in the CTA group (-0.7°). Nickel levels remained normal, and there were no complications.

CONCLUSIONS

This is the first randomized clinical trial of a novel SNT rod for treating patients with AIS, noting it to be safe and has potential to gradually correct scoliosis over time. This study serves as a pilot and platform to properly power future large-scale studies to demonstrate efficacy and superiority.

Corrosion of Harrington rod in idiopathic scoliosis: long-term effects

PURPOSE

Metal implants have been used to treat adolescent idiopathic scoliosis since the 1960s. Only recently, however, it has the issue of metal-bone breakdown secondary to metal corrosion in situ come to light, raising concerns of possible long-term complications from the resulting metallosis and inflammation of spinal tissues. We present a case of a patient with neurological deficit, pain, and disability with Harrington rod in place for over 30 years, to bring attention to the issue of bio-corrosion of metal implants and its effect on human tissue. We call attention to the need for protocols to better diagnose and treat these patients.

METHODS

We provide a complete review of the history and clinical manifestations as well as serum metal, X-ray, and CT/myelogram test results.

RESULTS

A 52-year-old female with spinal fusion and Harrington rod presents with pain, lymphedema, disability, and neurological deficits including thoracic outlet syndrome, hyperreflexia, peripheral muscle weakness and atrophy, hypertonicity, Raynaud's phenomenon, and balance and gait abnormalities. Serum chromium levels were elevated (26.73 nmol). X-rays showed no evidence of rod breakdown. Serial X-rays can demonstrate subtle corrosive changes but were not available. Adhesive arachnoiditis was diagnosed via CT/myelogram.

CONCLUSION

We hypothesize that bio-corrosion is present in this case and that it is associated with intraspinal metallosis. Trauma secondary to a motor vehicle accident, as well as arachnoiditis, and their possible effects on this case are outlined. Challenges in proper diagnosis and management are discussed.

Serum Metal Concentrations in Patients With Titanium Ceramic Composite Cervical Disc Replacements

STUDY DESIGN

Prospective longitudinal study.

OBJECTIVE

The serum titanium (Ti) concentrations were examined in patients implanted with a PRESTIGE LP Cervical Disc System (Medtronic, Inc., Memphis, TN). The metal-on-metal disc with ball-in-trough articulation is made of titanium alloy/titanium carbide composite (Ti-6Al-4 V/TiC).

SUMMARY OF BACKGROUND DATA

Cervical disc arthroplasty provides a motion-preserving treatment alternative to anterior cervical discectomy and fusion for degenerative cervical disc disease. The articulating surfaces have a tendency to generate in vivo wear in the form of insoluble particulates (debris) and soluble metal ions. Not much information is available on the long-term metal concentrations observed in cervical disc arthroplasty and how these compare with the metal concentrations in Ti-based posterior fixation devices and other joint replacement implants.

METHODS

Thirty patients were enrolled after strict exclusion criteria that included no previous permanent metal implants and no professional exposure to metal particles. High-resolution inductively coupled plasma-mass spectrometry was used to assay blood serum titanium concentrations preoperatively and at 3, 6, 12, 24, 36, 60, and 84 months after surgery. The detection limit for Ti was 0.2 ng/mL. The Friedman test was used to make longitudinal statistical comparisons.

RESULTS

The median serum Ti concentrations determined preoperatively, and at 3, 6, 12, 24, 36, 60, and 84 months were 0.10, 1.22, 1.15, 1.27, 1.21, 1.46, 1.34, and 1.42 ng/mL, respectively. The serum Ti concentrations at all postoperative time points were significantly higher than that at the preoperative time point (Friedman P < 0.01).

CONCLUSION

The long-term postoperative serum Ti concentrations were significantly higher than the preoperative concentrations. The observed serum Ti concentrations in this study are lower than the reported concentrations in patients receiving posterior spinal instrumentation and metal or ceramic-on-polyethylene hip prostheses with Ti-alloy based stems and acetabular components.

LEVEL OF EVIDENCE

3.

A Comparison of Patient-Reported Outcome Measures Following Different Treatment Approaches for Adolescents with Severe Idiopathic Scoliosis: A Systematic Review

Adolescent idiopathic scoliosis (AIS) is a three-dimensional deformity of the spine which is usually not symptomatic and which can progress during growth and cause a surface deformity. In adulthood, if the final spinal curvature surpasses a certain critical threshold, the risk of health problems and curve progression is increased. Although surgery is usually recommended for curvatures exceeding 40° to 50° to stop curvature progression, recent reviews have shed some light on the long-term complications of such surgery and to the lack of evidence for such complicated procedures within the scientific literature. Furthermore, a number of patients are very fearful of having surgery and refuse this option or live in countries where specialist scoliosis surgery is not available. Other patients may be unable to afford the cost of specialist scoliosis surgery. For these patients the only choice is an alternative non-surgical treatment option. To examine the impact of different management options in patients with severe AIS, with a focus on trunk balance, progression of scoliosis, cosmetic issues, quality of life, disability, psychological issues, back pain, and adverse effects, at both the short-term (a few months) and the long-term (over 20 years). We searched CENTRAL, MEDLINE, EMBASE, CINHAL and two other databases up to January 2016 with no language limitations. We also checked the reference lists of relevant articles and conducted an extensive hand search of the grey literature. We searched for randomised controlled trials as well as prospective and retrospective controlled trials comparing spinal fusion surgery with no treatment or conservative treatment in AIS patients with a Cobb angle greater than 40°. We did not identify any evidence of superiority of effectiveness of operative compared to nonoperative interventions for patients with severe AIS. Within the present literature there is no clear evidence to suggest that a specific type of treatment is superior to other types of treatment.

Metal concentrations in the blood and tissues after implantation of titanium growth guidance sliding instrumentation

BACKGROUND

Growth guidance sliding treatment devices, such as Shilla (Medtronic, Minneapolis, MN USA) or LSZ-4D (CONMET, Moscow, Russia), used for the treatment of scoliosis in children who have high growth potential have unlocked fixtures that allow rods to slide during growth of the spine, which avoids periodical extensions. However, the probability of clinical complications associated with metallosis after implantation of such devices is poorly understood. The content of metal ions in the blood and tissues of pediatric patients treated for scoliosis using fusionless growth guidance sliding instrumentation has not yet been investigated.

PURPOSE

The aim of the present study was to measure the content of metal ions in the blood and tissues surrounding the implanted growth guidance sliding LSZ-4D devices made of titanium alloy (Ti6Al4V), and to identify the incidence of metallosis-associated clinical complications in some patients with these devices.

STUDY DESIGN

This is a one-center, case-control retrospective study.

PATIENTS SAMPLE

The study group included 25 patients with high growth potential (22 females, 3 males; average age at primary surgery for scoliosis treatment is 11.4±1.2 years old) who had sliding growth guidance instrumentation LSZ-4D (CONMET) implanted on 13 (range: 10-16) spine levels for 6±2 years. The LSZ-4D device was made from titanium alloy Ti6Al4V and consisted of two rectangular section rods and fixture elements. Locked fixtures were used on one spinal level, whereas the others were unlocked (sliding). The control group consisted of 13 patients (12 females and 1 male; 11±1.2 years old) without any implanted devices.

OUTCOME MEASURES

The content of Ti, Al, and V metal ions in the whole blood and tissues around the implanted device was measured. The incidences of metallosis-associated complications in the study group were recorded.

METHODS

Metal ion content was measured by the inductively coupled mass spectrometry method on quadrupolar NexION 300D (PerkinElmer Inc, Shelton, CT, USA).

RESULTS

Five of 25 patients in the study group developed metallosis-associated complications (two sinuses and three seroma in the lumbar part of the spine). Revisions were carried out in two of these patients. Ninety percent of the patients in the study group had increased content of Ti and V ions in the blood (2.8 and 4 times, respectively). Median content of Ti ions in soft tissues adjacentto implanted sliding device was more than 1,500-fold higher than that of the control group. These levels are much higher than previously reported for spinal instrumentation.

CONCLUSIONS

Increased content of Ti and V ions in the blood and especially in tissues around the titanium growth guidance sliding device LSZ-4D accompanied by clinical manifestations (seroma and sinuses) indicates the importance of improving wear resistance of such instrumentation with the coatings and the necessity to exchange sliding instrumentation once the child is fully grown.

Local and systemic metal ion release occurs intraoperatively during correction and instrumented spinal fusion for scoliosis

STUDY DESIGN

Prospective pilot study.

OBJECTIVES

The aim of this study was to measure titanium, niobium and aluminium levels in various intraoperative and postoperative samples to determine patterns of metal ion release that occur within the first month following instrumented spinal fusion. Raised serum metal ion levels are reported following instrumented spinal fusion in adolescent idiopathic scoliosis. The exact topological origin and chronology of metal ion release remains conjectural. Recent literature suggests an immediate rise in serum metal levels within the first postoperative week.

METHODS

Titanium, niobium and aluminium levels were measured before, during and after surgery in serum and local intraoperative fluid samples obtained from two pediatric patients undergoing posterior correction and instrumentation for scoliosis.

RESULTS

Measurable metal ion levels were detected in all local samples obtained from wound irrigation fluid, cell saver blood, and fluid that immersed metal universal reduction screw tabs. Postoperative serum metal ion levels were elevated compared to baseline preoperative levels. In general, metal ion levels were considerably higher in the intraoperative fluid samples compared to those observed in the serum levels.

CONCLUSION

Our findings of contextually high metal ion concentrations in intraoperative and early postoperative samples provide further empirical support of a 'putting-in' phenomenon of metal ion release following instrumented spinal fusion. This challenges existing beliefs that metal ion release occurs during an intermediate 'wearing-in' phase. We recommend thorough irrigation of the operative site prior to wound closure to dilute and remove intraoperative metal ion debris. Possibilities of filtering trace metal ions from cell saver content may be considered.

Increased frequency of delayed type hypersensitivity to metals in patients with connective tissue disease

BACKGROUND

Connective tissue disease (CTD) is a group of inflammatory disorders of unknown aetiology. Patients with CTD often report hypersensitivity to nickel. We examined the frequency of delayed type hypersensitivity (DTH) (Type IV allergy) to metals in patients with CTD.

METHODS

Thirty-eight patients; 9 with systemic lupus erythematosus (SLE), 16 with rheumatoid arthritis (RA), and 13 with Sjögren's syndrome (SS) and a control group of 43 healthy age- and sex-matched subjects were included in the study. A detailed metal exposure history was collected by questionnaire. Metal hypersensitivity was evaluated using the optimised lymphocyte transformation test LTT-MELISA(®) (Memory Lymphocyte Immuno Stimulation Assay).

RESULTS

In all subjects, the main source of metal exposure was dental metal restorations. The majority of patients (87%) had a positive lymphocyte reaction to at least one metal and 63% reacted to two or more metals tested. Within the control group, 43% of healthy subjects reacted to one metal and only 18% reacted to two or more metals. The increased metal reactivity in the patient group compared with the control group was statistically significant (P<0.0001). The most frequent allergens were nickel, mercury, gold and palladium.

CONCLUSIONS

Patients with SLE, RA and SS have an increased frequency of metal DTH. Metals such as nickel, mercury and gold are present in dental restorative materials, and many adults are therefore continually exposed to metal ions through corrosion of dental alloys. Metal-related DTH will cause inflammation. Since inflammation is a key process in CTDs, it is possible that metal-specific T cell reactivity is an etiological factor in their development. The role of metal-specific lymphocytes in autoimmunity remains an exciting challenge for future studies.

A novel pedicle screw with mobile connection: a pilot study

To prevent adjacent disc problems after spinal fusion, a pedicle screw with a mobile junction between the head and threaded shaft was newly developed. The threaded shaft of the screw has 10 degrees mobility in all directions, but its structure is to prevent abnormal translation and tilting. This screw was evaluated as follows: (1) endurance test: 10⁶ times rotational stress was applied; (2) biological reactions: novel screws with a mobile head and conventional screws with a fixed head were inserted into the bilateral pedicles of the L3, L4, and L5 in two mini pigs with combination. Eight months after surgery, vertebral units with the screw rod constructs were collected. After CT scan, the soft and bony tissues around the screws were examined grossly and histologically. As a result, none of the screws broke during the endurance test stressing. The mean amount of abrasion wear was 0.0338 g. In the resected mini pig section, though zygapophyseal joints between fixed-head screws showed bony union, the amount of callus in the zygapophyseal joints connected with mobile-head screws was small, and joint space was confirmed by CT. No metalloses were noted around any of the screws. Novel screws were suggested to be highly durable and histologically safe.