Georg schmorl prize of the German spine society (DWG) 2021: Spinal Instability Spondylodiscitis Score (SISS)—a novel classification system for spinal instability in spontaneous spondylodiscitis

Abstract

Purpose Even though spinal infections are associated with high mortality and morbidity, their therapy remains challenging due to a lack of established classification systems and widely accepted guidelines for surgical treatment. This study’s aim therefore was to propose a comprehensive classification system for spinal instability based on the Spinal Instability Neoplastic Score (SINS) aiding spine surgeons in choosing optimal treatment for spontaneous spondylodiscitis. Methods Patients who were treated for spontaneous spondylodiscitis and received computed tomography (CT) imaging were included retrospectively. The Spinal Instability Spondylodiscitis Score (SISS) was developed by expert consensus. SINS and SISS were scored in CT-images by four readers. Intraclass correlation coefficients (ICCs) and Fleiss’ Kappa were calculated to determine interrater reliabilities. Predictive validity was analyzed by cross-tabulation analysis. Results A total of 127 patients were included, 94 (74.0%) of which were treated surgically. Mean SINS was 8.3 ± 3.2, mean SISS 8.1 ± 2.4. ICCs were 0.961 (95%-CI: 0.949–0.971) for total SINS and 0.960 (95%-CI: 0.946–0.970) for total SISS. SINS yielded false positive and negative rates of 12.5% and 67.6%, SISS of 15.2% and 40.0%, respectively. Conclusion We show high reliability and validity of the newly developed SISS in detecting unstable spinal lesions in spontaneous spondylodiscitis. Therefore, we recommend its use in evaluating treatment choices based on spinal biomechanics. It is, however, important to note that stability is merely one of multiple components in making surgical treatment decisions.

Case Report: Campylobacter fetus caused pyogenic spondylodiscitis with a presentation of cauda equina syndrome after instrumented lumbar fusion surgery

“…Evidence-based therapeutic concepts for infectious spondylodiscitis of the lumbar spine are still lacking (11). However, the latest publications discuss the rationale for using newly developed classification systems in improving the treatment of spondylodiscitis (12,13). CF-caused pyogenic spondylodiscitis is very rare, whereby reported cases predominantly occurred in high-risk patients, as did in our reported case, but contrary to our case, without previous instrumented lumbar fusion surgery (1-8).…”

“…Evidence-based therapeutic concepts for infectious spondylodiscitis of the lumbar spine are still lacking ( 11 ). However, the latest publications discuss the rationale for using newly developed classification systems in improving the treatment of spondylodiscitis ( 12 , 13 ).…”

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

“…30 The study by Schömig et al reported ICCs for interobserver reliability for the SINS and SISS as 0.961 and 0.960, respectively. 27 ICCs for the SITE Score were 0.989 (95% CI 0.975-0.997, p < 0.01) in the first round of 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. Even though the patient cohorts for the SISS and the SITE Score were fundamentally different, our resulting ICCs support the high interrater reliability of our scoring system compared to alternate scoring systems like the SISS and clinically proven scoring systems like the SINS.…”

“…23 The resulting SINS system has become well established in the oncology spine surgeon community to help with decision-making for spinal neoplastic disease but unfortunately was not immediately transferable to spinal infections. 27 In response, Schömig et al published a variation of the SINS called the "Spinal Instability Spondylodiscitis Score" (SISS), 27 which determines insta-bility in spondylodiscitis cases. 28 The advantage of using the SISS appeared to be limited, as that scoring system resulted in a higher false-positive rate (unstable lesion with nonsurgical treatment) and lower false-negative rate (stable lesion with surgical treatment) than those associated with the SINS.…”

“…In addition, both scoring systems ignore neurological deficits. 23,27 This factor remains a shortcoming, as the prevention of neurological deficits is one of the main indications for surgery, and such deficits may in fact be a presenting symptom of spinal instability. 4,29 Another dedicated scoring system called the "Brighton Spondylodiscitis Score" 11 was developed to predict the need for surgery in patients with spondylodiscitis by using several factors, including neurological deficits.…”