Pyogenic spondylodiscitis : The quest towards a clinical-radiological classification

Midterm survival and risk factor analysis in patients with pyogenic vertebral osteomyelitis: a retrospective study of 155 cases

Background

Pyogenic vertebral osteomyelitis (VO) represents a clinical challenge and is linked to substantial morbidity and mortality. This study aimed to examine mortality as well as potential risk factors contributing to in-hospital mortality among patients with VO.

Methods

This retrospective analysis involved patients receiving treatment for VO at University Regensburg in Germany from January 1, 2000, to December 3, 2020. It included in-hospital mortality rate, comorbidities and pathogens. Patients were identified using ICD-10 diagnosis codes: M46.2, M46.3, M46.4, and M46.5. Kaplan-Meier probability plots and odds ratios (OR) for mortality were calculated.

Results

Out of the total cohort of 155 patients with VO, 53 patients (34.1%) died during a mean follow-up time of 87.8 ± 70.8 months. The overall mortality was 17.2% at one year, 19.9% at two years and 28.3% at five years. Patients with congestive heart failure (p = 0.005), renal disease (p < 0.001), symptoms of paraplegia (p = 0.029), and sepsis (p = 0.006) demonstrated significantly higher overall mortality rates. In 56.1% of cases, pathogens were identified, with Staphylococcus aureus (S. aureus) and other unidentified pathogens being the most common. Renal disease (OR 1.85) and congestive heart failure (OR 1.52) were identified as significant risk factors.

Conclusion

Early assessment of the specific risk factors for each patient may prove beneficial in the management and treatment of VO to reduce the risk of mortality. These findings demonstrate the importance of close monitoring of VO patients with underlying chronic organ disease and early identification and treatment of sepsis. Prioritizing identification of the exact pathogens and antibiotic sensitivity testing can improve outcomes for patients in this high-risk group.

Anterior Column Reconstruction of Destructive Vertebral Osteomyelitis at the Thoracolumbar Spine with an Expandable Vertebral Body Replacement Implant: A Retrospective, Monocentric Radiological Cohort Analysis of 24 Cases

BACKGROUND

Vertebral osteomyelitis (VO) often necessitates surgical intervention due to bone loss-induced spinal instability. Anterior column reconstruction, utilizing expandable vertebral body replacement (VBR) implants, is a recognized approach to restore stability and prevent neurological compromise. Despite various techniques, clinical evidence regarding the safety and efficacy of these implants in VO remains limited.

METHODS

A retrospective cohort analysis, spanning 2000 to 2020, was conducted on 24 destructive VO cases at a Level 1 orthopedic trauma center. Diagnosis relied on clinical, radiological, and microbiological criteria. Patient demographics, clinical presentation, surgical interventions, and radiological outcomes were assessed.

RESULTS

The study included 24 patients (62.5% male; mean age 65.6 ± 35.0 years), with 58% having healthcare-associated infections (HAVO). The mean radiological follow-up was 137.2 ± 161.7 weeks. Surgical intervention significantly improved the bi-segmental kyphotic endplate angle (BKA) postoperatively (mean -1.4° ± 13.6°). However, a noticeable loss of correction was observed over time. The study reported a mortality rate of 1/24.

CONCLUSIONS

Anterior column reconstruction using expandable VBR effectively improved local spinal alignment in destructive VO. However, the study underscores the necessity for prolonged follow-up and continuous research to refine surgical techniques and postoperative care. Addressing long-term complications and refining surgical approaches will be pivotal as the field progresses.

Evaluation of Classification Systems and Their Correlation With Clinical and Quality-of-life Parameters in Patients With Surgically Treated Spondylodiskitis

INTRODUCTION

Surgical classifications for spondylodiscitis (SD) typically include radiologic features and the status of neurologic impairment. Clinical factors such as preoperative pain, function/disability, overall quality of life (QoL), and risk of recurrence and mortality, which are necessary for a comprehensive assessment of SD and measurement of treatment success, are not considered. There is a lack of external validation of SD classifications. The aim of this study was to validate classifications of SD and to correlate these classifications with the above clinical factors.

METHODS

One hundred fourteen patients from a prospective SD register (2008-2020) with available imaging, preoperative neurologic status, backpain, function/disability data (Oswestry Disability Index and Core Outcome Measures Index), QoL data (Short Form 36, European Quality-of-life Questionnaire), and a 1-year follow-up were retrospectively classified according to Akbar, Homagk, and Pola classifications. Interrater reliability, correlation among classifications, and correlation between classifications and QoL were calculated.

RESULTS

Interrater reliability was κ = 0.83 for Akbar, κ = 0.94 for Homagk, and κ = 0.99 for Pola. The correlation of Akbar with Pola and Homagk was moderate (ρ s = 0.47; ρ s = 0.46) and high between Pola and Homagk (ρ s = 0.7). No notable correlation was observed between any of the classifications and preoperative Oswestry Disability Index, Core Outcome Measures Index, QoL, mortality, and recurrence within 1 year. Only a weak correlation was observed between Homagk and preoperative leg pain and back pain.

CONCLUSION

Available SD classifications have a very good interrater reliability and moderate-to-high correlation with each other but lack correlation with preoperative pain, function/disability, and overall QoL. Because these factors are important for a comprehensive assessment of SD in severity, decision making, and prognosis, they should be included in future SD classifications. This could allow for more comprehensive treatment algorithms.

LEVEL OF EVIDENCE

Level II. Diagnostic study = prospective cohort study; development of diagnostic criteria.

DATA AVAILABILITY

The data sets used and analyzed during this study are available from the corresponding author on reasonable request.

Incidence and treatment trends of infectious spondylodiscitis in South Korea: A nationwide population-based study

The incidence of infectious spondylodiscitis (IS) has increased in recent years due to an increase in the numbers of older patients with chronic diseases, as well as patients with immunocompromise, steroid use, drug abuse, invasive spinal procedures, and spinal surgeries. However, research focusing on IS in the general population is lacking. This study investigated the incidence and treatment trends of IS in South Korea using data obtained from the Health Insurance Review and Assessment Service. A total of 169,244 patients (mean age: 58.0 years) diagnosed from 2010 to 2019 were included in the study. A total of 10,991 cases were reported in 2010 and 18,533 cases in 2019. Hence, there was a 1.5-fold increase in incidence rate per 100,000 people from 22.90 in 2010 to 35.79 in 2019 (P < 0.05). The incidence rate of pyogenic spondylodiscitis per 100,000 people increased from 15.35 in 2010 to 33.75 in 2019, and that of tuberculous spondylodiscitis decreased from 7.55 in 2010 to 2.04 in 2019 (P < 0.05, respectively). Elderly individuals ≥ 60 years of age accounted for 47.6% (80,578 patients) of all cases of IS. The proportion of patients who received conservative treatment increased from 82.4% in 2010 to 85.8% in 2019, while that of patients receiving surgical treatment decreased from 17.6% to 14.2% (P < 0.05, respectively). Among surgical treatments, the proportions of corpectomy and anterior fusion declined, while proportion of incision and drainage increased (P < 0.05, respectively). The total healthcare costs increased 2.9-fold from $29,821,391.65 in 2010 to $86,815,775.81 in 2019 with a significant increase in the ratio to gross domestic product. Hence, this population-based cohort study demonstrated that the incidence rate of IS has increased in South Korea. The conservative treatment has increased, while the surgical treatment has decreased. The socioeconomic burden of IS has increased rapidly.

Management of Lumbar Pyogenic Spondylodiscitis in Germany: A Cross-Sectional Analysis of Spine Specialists

OBJECTIVE

The incidence of pyogenic spondylodiscitis is increasing, and the disease is associated with considerable morbidity, mortality, long-term healthcare utilization and societal costs. Disease-specific treatment guidelines are lacking and there is little consensus regarding optimal conservative and surgical management. This cross-sectional survey of German specialist spinal surgeons sought to determine practice patterns and degree of consensus regarding the management of lumbar pyogenic spondylodiscitis (LPS).

METHODS

An electronic survey covering provider information, diagnostic approaches, treatment algorithms, and follow-up care of patients with LPS was distributed to members of the German Spine Society.

RESULTS

Seventy-nine survey responses were included in the analysis. Magnetic resonance imaging is the diagnostic imaging modality of choice for 87% of respondents; 100% routinely measure C-reactive protein in suspected LPS and 70% routinely take blood cultures before therapy initiation; 41% believe that surgical biopsy to obtain microbiological diagnosis should be carried out in all cases of suspected LPS, whereas 23% believe that surgical biopsy should only be carried out when empirical antibiotic therapy proves ineffective; 38% believe an intraspinal empyema should always be surgically evacuated, regardless of spinal cord compression. The median intravenous antibiotic duration is 2 weeks. The median total duration of the antibiotic therapy (intravenous and oral) is 8 weeks. Magnetic resonance imaging is the preferred imaging modality for follow-up of both conservatively and operatively treated LPS.

CONCLUSIONS

There exists considerable variation of care in the diagnosis, management, and follow-up of LPS among German spine specialists with little agreement on key aspects of care. Further research is required to understand this variation in clinical practice and to enhance the evidence base in LPS.

A novel scoring system concept for de novo spinal infection treatment, the Spinal Infection Treatment Evaluation Score (SITE Score): a proof-of-concept study

OBJECTIVE

De novo infections of the spine are an increasing healthcare problem. The decision for nonsurgical or surgical treatment is often made case by case on the basis of physician experience, specialty, or practice affiliation rather than evidence-based medicine. To create a more systematic foundation for surgical assessments of de novo spinal infections, the authors applied a formal validation process toward developing a spinal infection scoring system using principles gained from other spine severity scoring systems like the Spine Instability Neoplastic Score, Thoracolumbar Injury Classification and Severity Score, and AO Spine classification of thoracolumbar injuries. They utilized an expert panel and literature reviews to develop a severity scale called the "Spinal Infection Treatment Evaluation Score" (SITE Score).

METHODS

The authors conducted an evidence-based process of combining literature reviews, extracting key elements from previous scoring systems, and obtaining iterative expert panel input while following a formal Delphi process. The resulting basic SITE scoring system was tested on selected de novo spinal infection cases and serially refined by an international multidisciplinary expert panel. Intra- and interobserver reliabilities were calculated using the intraclass correlation coefficient (ICC) and Fleiss' and Cohen's kappa, respectively. A receiver operating characteristic analysis was performed for cutoff value analysis. The predictive validity was assessed through cross-tabulation analysis.

RESULTS

The conceptual SITE scoring system combines the key variables of neurological symptoms, infection location, radiological variables for instability and impingement of neural elements, pain, and patient comorbidities. Ten patients formed the first cohort of de novo spinal infections, which was used to validate the conceptual scoring system. A second cohort of 30 patients with de novo spinal infections, including the 10 patients from the first cohort, was utilized to validate the SITE Score. Mean scores of 6.73 ± 1.5 and 6.90 ± 3.61 were found in the first and second cohorts, respectively. The ICCs for the total score were 0.989 (95% CI 0.975-0.997, p < 0.01) in the first round of scoring system validation, 0.992 (95% CI 0.981-0.998, p < 0.01) in the second round, and 0.961 (95% CI 0.929-0.980, p < 0.01) in the third round. The mean intraobserver reliability was 0.851 ± 0.089 in the third validation round. The SITE Score yielded a sensitivity of 97.77% ± 3.87% and a specificity of 95.53% ± 3.87% in the last validation round for the panel treatment decision.

CONCLUSIONS

The SITE scoring concept showed statistically meaningful reliability parameters. Hopefully, this effort will provide a foundation for a future evidence-based decision aid for treating de novo spinal infections. The SITE Score showed promising inter- and intraobserver reliability. It could serve as a helpful tool to guide physicians' therapeutic decisions in managing de novo spinal infections and help in comparison studies to better understand disease severity and outcomes.

Diagnostic accuracy of fluorine-18 fluorodeoxyglucose positron emission tomography for suspected primary and postoperative pyogenic spondylitis

OBJECTIVE

Fluorine-18 fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET) and PET/CT have been suggested for confirming or excluding musculoskeletal infection but the diagnostic value of this tool for pyogenic spondylitis remains to be confirmed. This meta-analysis was performed to verify the accuracy of ¹⁸F-FDG PET and PET/CT in diagnosing suspected pyogenic spondylitis by performing a systematic review and meta-analysis.

METHODS

We conducted a comprehensive literature search of PubMed, Embase and Cochrane Library to retrieve diagnostic accuracy studies in which suspected pyogenic spondylitis was assessed with ¹⁸F-FDG PET or PET/CT. The pooled sensitivity, specificity, likelihood ratios, diagnostic odds ratio (DOR), summarized receiver operating characteristic curve (sROC) and the area under the sROC (AUC) were calculated by using Stata software.

RESULTS

A total of 18 eligible studies (660 patients) with suspected pyogenic spondylitis were included in the quantitative analysis. ¹⁸F-FDG PET and PET/CT illustrated relatively high sensitivity (0.91, 95% CI: 0.84-0.95) and specificity (0.90, 95% CI: 0.79-0.95) for the diagnosis of pyogenic spondylitis. The pooled DOR and AUC were 86.00 (95% CI, 31.00-240.00) and 0.96 (95% CI, 0.94-0.97), respectively. For diagnosing pyogenic spondylitis without previous spine surgery, the pooled sensitivity, specificity, DOR and AUC were 0.93 (95% CI, 0.85-0.97), 0.91 (95% CI, 0.77-0.97), 136 (95% CI, 35-530) and 0.97 (95% CI, 0.95-0.98), respectively. For diagnosing postoperative pyogenic spondylitis, the pooled sensitivity, specificity, DOR and AUC were 0.85 (95% CI, 0.71 to 0.93), 0.87 (95% CI, 0.66 to 0.96), 38 (95% CI, 9 to 167) and 0.92 (95% CI, 0.89 to 0.94), respectively.

CONCLUSION

¹⁸F-FDG PET and PET/CT presented satisfactory accuracy for diagnosing pyogenic spondylitis. The diagnostic effect of this nuclear imaging method for pyogenic spondylitis without previous spine surgery seems to be better than that for the postoperative ones. However, whether ¹⁸F-FDG PET and PET/CT could become a routine in patients with suspected pyogenic spondylitis remains to be confirmed.

LEVEL OF EVIDENCE

Level I evidence, a summary of meta-analysis.

A new classification of spondylodiscitis: possibility of validation and multidisciplinary expert consensus

Objective. To perform validation study of the E. Pola classification (2017) and to assess expert consensus on the diagnosis and treatment of infectious lesions of the spine in the national professional community.

Material and Methods. A clinical and radiological database on 15 cases of infectious spondylitis, as well as the information about original article by Pola and a Russian translation of the classification and tactical tables from this article, were distributed to 408 orthopedic traumatologists, neurosurgeons and radiologists who have experience in treating patients with spinal pathology and whose data are available in the registers of the relevant professional associations of the Russian Federation. The coincidence/difference in the responses concerning the definition of lesion types and the choice of treatment tactics, as well as proposals for the use of classification were assessed.

Results. Answers were obtained from 37 respondents from 11 regions of the Russian Federation. The general interobserver agreement index (Fleiss kappa) for all types of spondylodiscitis was 0.388 (95 % CI 0.374–0.402), including for lesion types: type A – 0.480 (95 % CI 0.460–0.499, type B – 0.300 (95 % CI 0.281–0.320), and type C – 0.399 (95 % CI 0.380–0.419). Agreement levels were higher among radiologists (type A – 0.486, type B – 0.484, and type C – 0.477), orthopedic traumatologists (type A – 0.474, type B – 0.380, and type C – 0.479), and specialists with clinical experience less than 10 years (type A – 0.550, type B – 0.318, and type C – 0.437). The pooled data for all 12 lesion subtypes showed general poor agreement (k = 0.247, CI 0.240–0.253), satisfactory level was found for B3.2 type (k = 0.561, CI 0.542–0.581), good agreement (k > 0.61) was achieved between orthopedic traumatologists for type B3.2 and between radiologists for B3.1 and B3.2 lesion types. Respondents refused to use basic treatment options for type A in 15.1 %, type B in 7.5 % and type C in 3.2 % of answers, while indicating the need for interventions through anterior approach in 24.7 %, 43.0 % and 46.2 %, respectively. Limitations of the classification use depending on the localization and etiology of spondylitis were noted. Authors recommended taking into account the presence of systemic inflammatory response syndrome, mandatory CT scanning, clarification of spinal instability criteria, and the addition of anterior surgical interventions to the treatment algorithm.

Conclusion. The Pola classification of spondylodiscitis is currently considered the most successful for tactical algorithms and implementation in broad clinical practice for spondylodiscitis. However, at the stages of its clinical application, there is an unsatisfactory interobserver expert consensus on the types of lesions, and there are limitations related to the etiology, localization and severity of the disease. A modified classification taking into account the identified limitations and including anterior procedures in the tactical options is advisable.

A Clinical Prediction Tool for MRI in Emergency Department Patients with Spinal Infection

Introduction

Patients with pyogenic spinal Infection (PSI) are often not diagnosed at their initial presentation, and diagnostic delay is associated with increased morbidity and medical-legal risk. We derived a decision tool to estimate the risk of spinal infection and inform magnetic resonance imaging (MRI) decisions.

Methods

We conducted a two-part prospective observational cohort study that collected variables from spine pain patients over a six-year derivation phase. We fit a multivariable regression model with logistic coefficients rounded to the nearest integer and used them for variable weighting in the final risk score. This score, SIRCH (spine infection risk calculation heuristic), uses four clinical variables to predict PSI. We calculated the statistical performance, MRI utilization, and model fit in the derivation phase. In the second phase we used the same protocol but enrolled only confirmed cases of spinal infection to assess the sensitivity of our prediction tool.

Results

In the derivation phase, we evaluated 134 non-PSI and 40 PSI patients; median age in years was 55.5 (interquartile range [IQR] 38–70 and 51.5 (42–59), respectively. We identified four predictors for our risk score: historical risk factors; fever; progressive neurological deficit; and C-reactive protein (CRP) ≥ 50 milligrams per liter (mg/L). At a threshold SIRCH score of ≥ 3, the predictive model’s sensitivity, specificity, and positive predictive value were, respectively, as follows: 100% (95% confidence interval [CI], 100–100%); 56% (95% CI, 48–64%), and 40% (95% CI, 36–46%). The area under the receiver operator curve was 0.877 (95% CI, 0.829–0.925). The SIRCH score at a threshold of ≥ 3 would prompt significantly fewer MRIs compared to using an elevated CRP (only 99/174 MRIs compared to 144/174 MRIs, P <0.001). In the second phase (49 patient disease-only cohort), the sensitivities of the SIRCH score and CRP use (laboratory standard cut-off 3.5 mg/L) were 92% (95% CI, 84–98%), and 98% (95% CI, 94–100%), respectively.

Conclusion

The SIRCH score provides a sensitive estimate of spinal infection risk and prompts fewer MRIs than elevated CRP (cut-off 3.5 mg/L) or clinician suspicion.

[Infections of the spine : Pyogenic spondylodiscitis and implant-associated vertebral osteomyelitis]

Pyogenic (unspecific) spondylodiscitis and implant-associated vertebral osteomyelitis (IAVO) are important diseases with the risk of neurological and septic complications. An early diagnosis is essential in which magnetic resonance imaging (MRI), histopathology and microbiological identification of the pathogen play key roles. The goals of conservative treatment in uncomplicated spondylodiscitis are antibiotic infection control and pain management. In the case of sepsis, neurological deficits, segmental instability or epidural abscesses surgical treatment of the infection with stabilization of the spine should be considered. In IAVO the formation of a mature biofilm represents the transition from acute to chronic infection. Acute infections can be treated by extensive debridement in combination with biofilm-active antibiotic treatment while retaining the implant. In chronic infections implant removal or exchange in combination with several weeks of antibiotic treatment is often necessary.

[Pyogenic spondylodiscitis: symptoms, diagnostics and therapeutic strategies]

BACKGROUND

Pyogenic spondylodiscitis is a rare disease that is being diagnosed with increasing frequency in recent years. It is associated with a high morbidity and mortality.

DIAGNOSIS

Often, because of its nonspecific symptoms, pyogenic spondylodiscitis is diagnose with some delay. In addition to pathogen detection, MRI is the gold standard to diagnose pyogenic spondylodiscitis. Also, x-ray imaging and CT can be carried out for surgical planning and for subsequent follow-up imaging. If blood or tissue cultures are negative, open surgical biopsies should be preferred over CT-guided biopsies.

THERAPY

The therapy can be conservative, such as immobilization, as well as antibiotics and analgesics, or surgical. If, for example, neurological deficits, spinale instabilities or deformities, septic disease progression or extensive abscess formations are present, surgical therapy is indicated. The surgical treatment strategies depend on the severity of the disease.

OUTLOOK

The prognosis is dependent on a rapid diagnosis and a swift start to therapy. There is no clear evidence with regard to treatment options (conservative vs. surgical therapy).