Advances in D-dimer testing: progress in harmonization of clinical assays and innovative detection methods.

The D-dimer is a sensitive indicator of coagulation and fibrinolysis activation, especially valuable as a biomarker of intravascular thrombosis. Measurement of plasma D-dimer levels plays a crucial role in the diagnosis and monitoring of conditions such as deep vein thrombosis, pulmonary embolism, and disseminated intravascular coagulation. A variety of immunoassays, including enzyme-linked immunosorbent assays, latex-enhanced immunoturbidimetric assays, whole-blood aggregation analysis, and immunochromatography assays, are widely used in clinical settings to determine D-dimer levels. However, the results obtained from different D-dimer assays vary significantly. These assays exhibit intra-method coefficients of variation ranging from 6.4% to 17.7%, and the measurement discrepancies among different assays can be as high as 20-fold. The accuracy and reliability of D-dimer testing cannot be guaranteed due to the lack of an internationally endorsed reference measurement system (including reference materials and reference measurement procedures), which may lead to misdiagnosis and underdiagnosis, limiting its full clinical application. In this review, we present an in-depth analysis of clinical D-dimer testing, summarizing the existing challenges, the current state of metrology, and progress towards harmonization. We also review the latest advancements in D-dimer detection techniques, which include mass spectrometry and electrochemical and optical immunoassays. By comparing the basic principles, the definition of the measurand, and analytical performance of these methods, we provide an outlook on the potential improvements in D-dimer clinical testing.

In-Vitro Diagnostic Reagent Evaluation of Commercially Available Cardiac Troponin I Assay Kits Using H/D Exchange Mass Spectrometry for Antibody-Epitope Mapping.

Cardiac troponin I (cTnI) is the biomarker of choice and considered a gold standard for the diagnosis of acute myocardial infarction. However, the quantitative results of cTnI assay kits from different manufacturers are not comparable. Based on the H/D exchange mass spectrometry (HDX-MS) workflow, we developed an in-vitro diagnostic reagent antibody evaluation strategy to analyze the interactions of epitopes and antibody cocktails─(R195, F12, S13) and (D1, D2, pAb2). The HDX results indicate that the quantitative result bias of the different reagents originates from the ability of antibodies to recognize various cTnI complex forms, such as free cTnI, hydrolyzed cTnI, and cTnI combined with cTnT or TnC as binary or ternary complexes (cTnIC, cTnTIC), in blood based on different epitopes. The data obtained from the peptide HDX of interest after treatment with various antibody cocktails clearly indicated epitope specificity. The consistency of quantitative results can be improved by a thorough investigation into the epitopes recognized by the antibodies of various diagnostic kits, which will lead to the standardization of cTnI diagnosis.

Commutability assessment of reference materials for homocysteine.

OBJECTIVES: Commutability of reference materials is essential for ensuring the traceability of patient measurement results and the technical basis for the use of reference materials. Commutability is only relevant for matrixed reference material; it is a prerequisite for the accuracy and authenticity of calibration methods. In this study, we evaluated the commutability of reference materials for homocysteine. METHODS: Five conventional measurement methods were applied to simultaneously measure 30 serum samples and seven homocysteine reference materials from the National Institute of Standards and Technology and the National Institute of Metrology. Liquid chromatography tandem-mass spectrometry was used as a reference method. Two methods were used to evaluate the commutability of the seven reference materials according to the Clinical and Laboratory Standards Institute EP30-A and the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) commutability assessment document. RESULTS: Among 35 combinations of the five conventional methods and seven reference materials, after evaluation in accordance with the EP30-A, the seven reference materials passed the commutability assessment, and 34 combinations were commutable. According to the IFCC, the commutability evaluation of 28 combinations was conclusive (commutable or non-commutable), while results for the remaining seven combinations could not be determined. CONCLUSIONS: The homocysteine reference materials showed good commutability. The sensitivity of the measurement procedure, measurement deviation and uncertainty, and differences in the "measurand" selected by different methods may affect the evaluation results. Additionally, different judgment standards for different methods may explain the observed variations in evaluation results.

Epitope mapping of antibodies in C-reactive protein assay kits by hydrogen-deuterium exchange mass spectrometry explains differential results across kits.

C-Reactive protein (CRP) is an important marker for in vitro diagnosis (IVD) of inflammation. However, CRP immunoturbidimetric kits from different manufacturers exhibit inconsistency in evaluation, making clinical diagnosis challenging. The use of immunological methods in diagnosis means that the differences in epitopes across kits may directly lead to inconsistent results. Therefore, to provide consistent results, it is essential to perform epitope mapping of different kits. The composition of antibodies in a single kit is typically complex, with a combination of polyclonal antibodies or monoclonal antibodies. Here, we show an epitope screening strategy for complex antibodies in a kit based on hydrogen-deuterium exchange mass spectrometry (HDX-MS). We applied this workflow to successfully map the epitopes for three kits from three different manufacturers and compared their quantitative results. We obtained different quantitative results using kits from different manufacturers upon epitope mapping, confirming the correlation between the quantitative results and the epitopes. Thus, we have established a workflow based on HDX-MS to screen epitopes in IVD kits. This work helps determine the quantitative accuracy of a kit based on structural information, can guide the design and production of IVD reagents, and further improves the accuracy of IVD.

Research advances in hydrogen-deuterium exchange mass spectrometry for protein epitope mapping.

With the development of biomedical technology, epitope mapping of proteins has become critical for developing and evaluating new protein drugs. The application of hydrogen-deuterium exchange for protein epitope mapping holds great potential. Although several reviews addressed the hydrogen-deuterium exchange, to date, only a few systematic reviews have focused on epitope mapping using this technology. Here, we introduce the basic principles, development history, and review research progress in hydrogen-deuterium exchange epitope mapping technology and discuss its advantages. We summarize the main hurdles in applying hydrogen-deuterium exchange epitope mapping technology, combined with relevant examples to provide specific solutions. We describe the epitope mapping of virus assemblies, disease-associated proteins, and polyclonal antibodies as examples of pattern introduction. Finally, we discuss the outlook of hydrogen-deuterium exchange epitope mapping technology. This review will help researchers studying protein epitopes to gain a more comprehensive understanding of this technology.

Analysis of B-type natriuretic peptide impurities using label-free data-independent acquisition mass spectrometry technology.

Objectives: Synthetic B-type natriuretic peptide (BNP) is employed in most clinical testing platforms as a raw material of calibrator. Characterization of impurities with structures similar (BNPstrimp compounds) to that of BNP is a reasonable way to decrease clinical measurement errors and improve drug safety. Methods: A novel quantitative method targeted towards BNPstrimp compounds was developed. First, the peptide samples were separated and identified using ultra-performance liquid chromatography, coupled with high-resolution mass spectrometry (MS). To evaluate biological activity further, BNPstrimp immunoaffinity was investigated using western blot (WB) assays. Second, a quantitative label-free data-independent acquisition (DIA) MS approach was developed, and the internal standard peptide (ISP) was hydrolyzed. Absolute quantification was performed using an isotope dilution MS (ID-MS) approach. Third, method precision was investigated using the C-peptide reference material. Results: Seventeen BNPstrimp compounds were identified in synthetic BNP, and 10 of them were successfully sequenced. The immunoassay results indicated that deaminated, oxidized, and isomerized BNPstrimp compounds exhibited weaker immunoaffinity than intact BNP1-32. The mass fraction of the synthetic solid ISP1-16, quantified by ID-MS, was 853.5 (±17.8) mg/g. Validation results indicated that the developed method was effective and accurate for the quantitation of the well-separated BNP impurities. Conclusions: The developed approach was easy to perform, and it was suitable for the parallel quantification of low-abundance BNPstrimp compounds when they performed a good separation in liquid chromatography. The quantitative results were comparable and traceable. This approach is a promising tool for BNP product quality and safety assessment.

Double-level isthmic spondylolisthesis treated with posterior lumbar interbody fusion with cage.

Objective: Double-level isthmic spondylolisthesis in the lumbar spine is rare. The authors report on 21 cases of double-level isthmic spondylolisthesis treated by posterior lumbar interbody fusion (PLIF) with cage.Patients and methods: Between 2005 and 2015, twenty-one patients with double-level isthmic spondylolisthesis who underwent posterior lumbar interbody fusion (PLIF) with cage were reviewed retrospectively. The VAS (Visual Analogue Scale) and JOA (Japanese Orthopedic Association) score were used to evaluate preoperative and postoperative clinical outcomes.Results: The back pain and sciatica decreased from 6.53 and 4.24 points preoperatively to 1.80 and 1.18 points on the VAS at final follow-up, respectively. The average JOA score improved from 13.4 ± 3.2 preoperative to 25.4 ± 1.5 (range, 17-28) points postoperative. The average recovery rate was 76.9%. The good and excellent rate was 85.7% (18/21). The fusion rate was 95.2% (20/21). Changes in disc height, degree of listhesis, whole lumbar lordosis, and sacral inclination following surgery were also observed.Conclusions: Our results suggest that PLIF with cage appears to be an appropriate technique for the treatment of double-level isthmic spondylolisthesis.

Analytical barriers in clinical B-type natriuretic peptide measurement and the promising analytical methods based on mass spectrometry technology.

B-type natriuretic peptide (BNP) is a circulating biomarker that is mainly applied in heart failure (HF) diagnosis and to monitor disease progression. Because some identical amino acid sequences occur in the precursor and metabolites of BNP, undesirable cross-reactions are common in immunoassays. This review first summarizes current analytical methods, such as immunoassay- and mass spectrometry (MS)-based approaches, including the accuracy of measurement and the inconsistency of the results. Second, the review presents some promising approaches to resolve the current barriers in clinical BNP measurement, such as how to decrease cross-reactions and increase the measurement consistency. Specific approaches include research on novel BNP assays with higher-specificity chemical antibodies, the development of International System of Units (SI)-traceable reference materials, and the development of structure characterization methods based on state-of-the-art ambient and ion mobility MS technologies. The factors that could affect MS analysis are also discussed, such as biological sample cleanup and peptide ionization efficiency. The purpose of this review is to explore and identify the main problems in BNP clinical measurement and to present three types of approaches to resolve these problems, namely, materials, methods and instruments. Although novel approaches are proposed here, in practice, it is worth noting that the BNP-related peptides including unprocessed proBNP were all measured in clinical BNP assays. Therefore, approaches that aimed to measure a specific BNP or proBNP might be an effective way for the standardization of a particular BNP form measurement, instead of the standardization of "total" immunoreactive BNP assays in clinical at present.

Enhancing the accuracy of measurement of small molecule organic biomarkers.

Over two decades, the Organic Analysis Working Group (OAWG) of the Consultative Committee for Amount of Substance: Metrology in Chemistry and Biology (CCQM) has organized a number of comparisons for clinically relevant small molecule organic biomarkers. The aim of the OAWG community is to be part of the coordinated international movement towards accuracy and comparability of clinical measurements that will, in turn, minimize the wastage of repeat testing and unnecessary therapy to create a sustainable healthcare industry. International and regional directives/requirements on metrological traceability of calibrators and control materials are in place. Metrology institutes worldwide maintain infrastructure for the practical realization of metrological traceability and demonstrate the equivalence of their measurement capabilities through participation in key comparisons organized under the auspices of the CCQM. These institutes provide certified reference materials, as well as other dedicated value-assignment services benefiting the in-vitro diagnostic (IVD) industry, reference (calibration) laboratories and the clinical chemistry laboratories. The roles of these services in supporting national, regional, and international activities to ensure the metrological traceability of clinical chemistry measurements are described. Graphical abstract.

Association of VDR-FokI and VDBP-Thr420Lys polymorphisms with cervical spondylotic myelopathy: A case-control study in the population of China.

BACKGROUND: Cervical spondylotic myelopathy (CSM), a common degenerative disorder, is characterized by chronic progressive compression of the cervical spinal cord. The present case-control study aimed to explore the potential role of VDR-FokI and VDBP-Thr420Lys polymorphisms in the susceptibility to CSM in the Chinese population. METHODS: The study enrolled 318 CSM patients and 282 healthy individuals whose clinical data were retrospectively analyzed. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis was used to genotype VDR-FokI and VDBP-Thr420Lys polymorphisms. The severity of CSM was assessed using the Japanese Orthopaedic Association (JOA) score with magnetic resonance imaging (MRI) of cervical vertebra. A nonconditional binary logistic regression model was conducted for assessing the risk factors of CSM. RESULTS: Patients in the CSM group had longer time duration to bend over desk working than the control group. The ff genotype and f allele frequency of VDR-FokI were elevated in CSM patients. Elevated Ff + ff genotype and f allele frequency of VDR-FokI might increase the risk of CSM. The VDR-FokI polymorphism was associated with nucleus pulposus capillary invasion, necrosis, hyaline degeneration and fibrosis, genesis and hyperplasia of cartilage-like cells, and fibrocyst in the fibrous ring. The VDR-FokI and VDBP-Thr420Lys genotypes conformed to Hardy-Weinberg equilibrium which showed that VDR-FokI and VDBP-Thr420Lys had group representation characteristics. CONCLUSION: Binary logistic regression analysis confirmed that VDR-FokI polymorphism and the time to bend over desk working were risk factors of CSM. Our results indicate that VDR-FokI polymorphism may be closely associated with the risk of CSM.

Development of a matrix-based candidate reference material of total homocysteine in human serum.

We developed and evaluated a candidate serum reference material to help improve clinical routine measurement, and to provide traceability of the measurement results. D8-Homocystine, dithiothreitol, and acetonitrile were used as an internal standard, the reducing agent, and the protein precipitating agent, respectively. A triple quadrupole mass spectrometer with an electrospray ionization source was used for monitoring the transitions (m/z 140.0 → 94.0, 136.0 → 90.0) in multiple-reaction-monitoring mode. We used a calibration model relying on bracketing and gravimetric measurements to give SI-traceability and higher accuracy to serum value assignments. The method was evaluated for accuracy using NIST Standard Reference Material SRM1955. The results of the three concentrations (1, 2, and 3) of total homocysteine in human serum samples were determined by an isotope-dilution liquid chromatography-tandem mass spectrometry method; tHcy 1 is 28.8 ± 1.1 µmol/L, tHcy 2 is 17.93 ± 0.57 µmol/L, and tHcy 3 is 14.38 ± 0.46 µmol/L. Graphical abstract The workflow diagram.

Absolute quantification methods for Prostate-Specific antigen by Isotope-Dilution mass spectrometry.

Prostate-specific antigen (PSA) is a diagnostic marker for prostate cancer; however, because it is a macromolecular glycoprotein with complex and diverse isoforms, it is difficult to standardize clinical PSA detection results. To overcome this limitation, herein, naturally extracted PSA was characterized as free PSA (fPSA), and the PSA solution was successfully quantified by amino acid analysis coupled with isotope-dilution mass spectrometry (AAA-IDMS) and enzymatic hydrolysis-IDMS; the results could be traced to the International System of Units (SI) through absolutely quantified amino acids and peptides. After protein hydrolysis or digestion condition optimization, amino acids and signature peptides were detected by liquid chromatography-mass spectrometry with the multiple reaction monitoring mode. The mass concentrations of PSA obtained through AAA-IDMS and enzymatic hydrolysis-IDMS were (75.3 ±â€¯1.5) µg/g (k = 2) and (74.7 ±â€¯1.7) µg/g (k = 2), respectively. The PSA weighted average mass concentration was (75.0 ±â€¯1.6) µg/g (k = 2). The consistency assessment between the two methods was successfully validated, ensuring absolute quantitative accuracy. This study lays the foundation for the development of high-order reference materials for the clinical detection of PSA, which can improve the accuracy, reliability, and consistency of clinical PSA test results.

Occurrence and distribution of salsolinol-like compound, 1-acetyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline (ADTIQ) in parkinsonian brains.

Parkinson's disease (PD) arises from the loss of dopaminergic neurons in the substantia nigra. 1-Methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) is well known to cause Parkinsonism in humans with neurotoxicity specific for dopaminergic neurons. The experience with MPTP supports the hypothesis that endogenous or xenobiotic neurotoxins are involved in the pathogenesis of PD in humans. In our study, 1-acetyl-6, 7-dihydroxy-1, 2, 3, 4-tetrahydro-isoquinoline (ADTIQ), a novel compound, was found in frozen human brain tissues. The formation of ADTIQ was demonstrated using dopamine and methylglyoxal under physiological conditions. Methylglyoxal is a by-product of glycolysis. ADTIQ and its precursors, dopamine and methylglyoxal, were detected in different regions of frozen human brains such as the substantia nigra, caudate nucleus, putamen, frontal cortex, and the cerebellum. A significant difference in ADTIQ levels between control and Parkinson's patients was found; for instance, the ADTIQ level in putamen of PD patients was 0.76 ± 0.27 nmol/g compared to 0.10 ± 0.01 nmol/g in control. Our results might indicate that ADTIQ is possibly related to Parkinson's disease.

Growth stimulation expressed gene 2 (ST2): Clinical research and application in the cardiovascular related diseases.

As an interleukin (IL)-1 receptor family member, scientists found that when circulating soluble growth stimulation expressed gene 2 (sST2) is low, its ligand, IL-33, will bind to ST2L to exert protective effects on various types of cells. On the other hand, competitive binding of IL-33 occurs when sST2 concentrations are increased, followed by a reduction in the amount available for cell protection. Based on this mechanism, the usage of sST2 is to identify the population of high-risk patients with cardiovascular disease. In recent years, the role of serum sST2 in the occurrence, diagnosis, prognosis, and treatment of cardiovascular diseases has been gradually accepted by doctors. This manuscript systemically reviews the biological functions and applications of sST2 in disease diagnosis and treatment, especially for cardiovascular diseases. In clinical testing, since IL-33 can negatively impact sST2 measurement accuracy, the properties of current assay kits have been summarized and discussed to provide a clear view of the clinical chemistry results. Although sST2 is a promising biomarker, there are few quantitative approaches available for clinical testing. In this context, a mass spectrometry (MS)-based approach might be an option, as this is a powerful analytical tool to distinguish structurally related molecules in the matrix and decrease false-positive results in clinical testing. Moreover, approaches developed based on MS would be an ideal way to further study sST2 standardization.

Development of a primary reference material of natural C-reactive protein: verification of its natural pentameric structure and certification by two isotope dilution mass spectrometry.

C-reactive protein (CRP) is one of the most commonly used biomarkers for inflammation. The standardisation of a procedure for the detection of CRP has attracted significant attention globally, and primary reference materials of CRP based on the recombinant expression of E. coli that exist in the form of monomers have been developed. However, a primary reference material of natural CRP is still required to achieve the exact matching of CRP measurements in secondary reference materials (e.g. CRP in frozen human serum). Herein, the development process for a certified reference material of natural CRP is reported, namely GBW09228. The raw material employed in this study was CRP extracted and purified from human body fluid, and exhibits a natural and verified pentameric structure. Through the use of amino acid analysis isotope dilution mass spectrometry (AAA-IDMS) and signature peptide-IDMS, this reference material was certified, and its certification results can be traced to SI units. The developed method was evaluated for its accuracy using the international comparison tests of the National Metrology Institute of Japan (NMIJ) and the Korea Research Institute of Standards and Science (KRISS). Overall, a CRP primary certified reference material (CRM) of well-characterised purity was determined that could be used to calibrate an IDMS-based reference method, that could then be used to assign target values to secondary CRMs. These secondary CRMs could in turn be used to calibrate and verify the accuracy of immunoassays, thereby giving a good foundation for establishing a complete traceability chain for CRP.

Rapid Detection of Multiple Classes of ß-Lactam Antibiotics in Blood Using an NDM-1 Biosensing Assay.

Currently, assays for rapid therapeutic drug monitoring (TDM) of ß-lactam antibiotics in blood, which might be of benefit in optimizing doses for treatment of critically ill patients, remain challenging. Previously, we developed an assay for determining the penicillin-class antibiotics in blood using a thermometric penicillinase biosensor. The assay eliminates sample pretreatment, which makes it possible to perform semicontinuous penicillin determinations in blood. However, penicillinase has a narrow substrate specificity, which makes it unsuitable for detecting other classes of ß-lactam antibiotics, such as cephalosporins and carbapenems. In order to assay these classes of clinically useful antibiotics, a novel biosensor was developed using New Delhi metallo-ß-lactamase-1 (NDM-1) as the biological recognition layer. NDM-1 has a broad specificity range and is capable of hydrolyzing all classes of ß-lactam antibiotics in high efficacy with the exception of monobactams. In this study, we demonstrated that the NDM-1 biosensor was able to quantify multiple classes of ß-lactam antibiotics in blood plasma at concentrations ranging from 6.25 mg/L or 12.5 mg/L to 200 mg/L, which covered the therapeutic concentration windows of the tested antibiotics used to treat critically ill patients. The detection of ceftazidime and meropenem was not affected by the presence of the ß-lactamase inhibitors avibactam and vaborbactam, respectively. Furthermore, both free and protein-bound ß-lactams present in the antibiotic-spiked plasma samples were detected by the NDM-1 biosensor. These results indicated that the NDM-1 biosensor is a promising technique for rapid TDM of total ß-lactam antibiotics present in the blood of critically ill patients.

Rapid personalized AMR diagnostics using two-dimensional antibiotic resistance profiling strategy employing a thermometric NDM-1 biosensor.

Antimicrobial resistance (AMR) threatens global public health and modern surgical medicine. Expression of ß-lactamase genes is the major mechanism by which pathogens become antibiotic resistant. Pathogens expressing extended spectrum ß-lactamases (ESBL) and carbapenemases (CP) are especially difficult to treat and are associated with increased hospitalization and mortality rates. Despite considerable effort, identification of ESBLs and CPs in a clinically relevant timeframe remains challenging. In this study, a two-dimensional AMR profiling assay strategy was developed employing panels of antibiotics (penicillins, cephamycins, oximino-cephalosporins and carbapenems) and ß-lactamases inhibitors (avibactam and EDTA). The assay required the development of a novel biosensor that employed New Delhi metallo-ß-lactamase-1 (NDM-1) as the sensing element. Functionally probing ß-lactamase activity using substrates and inhibitors combinatorically increased the informational content that enabled the development of assays capable of simultaneous, differential identification of multiple ß-lactamases expressed in a single bacterial isolate. More specifically, the assay enabled the simultaneous identification of ESBL and CP in mock samples, as well as in an engineered construct which co-expressed these ß-lactamases. The NDM-1 biosensor assay was 16 times and 8 times more sensitive than the ESBL Nordmann/Dortet/Poirel (NDP) and Carba Nordmann/Poirel (NP) assays, respectively. In a retrospective study, NDM-1 biosensor assays were able to differentially identify ESBLs, metallo-CPs and serine-CPs ß-lactamases in 23 clinical isolates with 100% accuracy. An assay algorithm was developed which accelerated data analytics reducing turnaround to <1 h. The assay strategy integrated with AI-based data analytics has the potential to provide physicians with a comprehensive readout of patient AMR status.

Purity determination of synthetic glucagon using a mass balance approach.

Due to the widespread use of synthetic peptide drugs, their quantification and the analysis of impurities have become increasingly important in clinical and medical settings. Moreover, quantifying proteins using synthetic peptides as internal or external standards is a general approach, and the key to this approach is the knowing purities of the peptides. In this paper, synthetic glucagon was quantified using a mass balance method. The impurities in glucagon were analyzed and then accurately quantified separately. Karl Fischer (KF) titration and ion chromatography (IC) were used to determine the water and trifluoroacetic acid (TFA) contents in the samples, respectively. Furthermore, the inorganic ion content in the samples was determined by inductively coupled plasma mass spectrometry (ICP-MS). The sequence of peptide impurities was identified by a Thermo Fisher Orbitrap mass. Samples were determined to be 896.36 ± 0.68 mg/g after subtracting all impurity masses from the sample mass. The result can be traced to SI units.

Double-level isthmic spondylolisthesis treated with posterior lumbar interbody fusion: A review of 32 cases.

OBJECTIVE: The incidence of double-level isthmic spondylolisthesis is rare. The aim of this study is to evaluate the short-term functional and radiological outcomes of surgical treatment for double-level isthmic spondylolisthesis. PATIENTS AND METHODS: Between 2004 and 2014, thirty-two patients with double-level isthmic spondylolisthesis who underwent posterior lumbar interbody fusion (PLIF) with autogenous bone chips were reviewed retrospectively. The clinical outcomes were measured by VAS (Visual analog scale) and JOA(Japanese Orthopedic Association) score. RESULTS: At an average follow-up of 2.8 years, the mean score on the VAS of back pain and sciatica decreased from 6.48 and 4.26 points preoperatively to 1.82 and 1.10 points at final follow-up, respectively. The average JOA score improved from 13.8±3.1 preoperative to 25.6±1.3 (range, 17-28) points postoperative. The average recovery rate was 77.6%. The good and excellent rate was 84.3% (27/32). The fusion rate was 87.5% (28/32). Changes in disc height, degree of listhesis, whole lumbar lordosis, and sacral inclination between the pre- and postoperative periods were significant. CONCLUSIONS: Our findings suggest that PLIF with autogenous bone chips for double-level isthmic spondylolisthesis could yield good functional short-term results. It seems to be a viable approach in the treatment of double-level isthmic spondylolisthesis.

Comparison of posterior lumbar interbody fusion (PLIF) with autogenous bone chips and PLIF with cage for treatment of double-level isthmic spondylolisthesis.

INTRODUCTION: Spondylolytic defects involving multiple vertebral levels are rare. It is reported that only 1.48% of patients with back pain were diagnosed with multi-level spondylolysis. The incidence of multiple-level spondylolisthesis is even rarer, so far there have been few reports of multi-level isthmic spondylolisthesis in the literature. The aim of this study is to evaluate clinical and radiological outcomes of two different fusion techniques for treatment of double-level isthmic spondylolisthesis. METHODS: Fifty-four patients who were managed surgically for treatment of double-level symptomatic isthmic spondylolisthesis were included in this study. Between May 2004 and September 2012, 29 consecutive patients underwent posterior lumbar interbody fusion (PLIF) with autogenous bone chips (group I) at Foshan Hospital of Traditional Chinese Medicine, Guangdong, China. Between March 2005 and December 2013, 25 consecutive patients underwent PLIF with cage (group II) at Zhujiang Hospital of Southern Medical University, Guangdong, China. The mean follow-up periods were 27.2 and 26.8 months, respectively. RESULTS: The mean VAS scores of back and leg pain significantly decreased from 7.2 to 2.2 and 5.8 to 2.1 in the group I and from 7.0 to 1.9 and 6.1 to 1.8 in the group II, respectively. In the group I, mean ODI scores improved significantly from 54% to 14.2% and, in the group II, from 60% to 12.6%. In both groups, VAS and ODI scores significantly changed from pre- to postoperatively (p<0.001), but postoperative outcome between groups was statistically not significant. Solid union was observed in 27 of 29 patients (89.6%) in the group I and in 22 of 25 patients (88%) in the group II, without statistically significant differences (p>0.05). In both groups, changes in disc height, degree of listhesis, and whole lumbar lordosis between the pre- and postoperative periods were significant. CONCLUSION: Clinical and functional outcomes demonstrate no significant differences between groups in treating back and leg pain of adult patients with double-level isthmic spondylolisthesis.