Bacterial identification in herniated intervertebral discs: a prospective cohort study.

BACKGROUND CONTEXT: Reports of Cutibacterium acnes isolated in cultures of intervertebral disc samples suggest it as possibly responsible for inflammatory conditions causing Modic changes on spinal magnetic resonance imaging (MRI). PURPOSE: Our objective was to investigate the prevalence of C. acnes in samples of intervertebral disc of patients with lumbar disc herniation; to investigate prognostic factors and the relationship of Modic changes with infection 1 year after microdiscectomy. STUDY DESIGN: Prospective cohort study. PATIENT SAMPLE: In this single-center study, patients consecutively operated on for disc herniation had samples of the disc, multifidus muscle and ligamentum flavum (as an indication of contamination) extracted for culture. OUTCOME MEASURES: Age, sex, alcohol and tobacco consumption, body mass index; function, pain, and Modic chances in MRI before surgery and MRI 1 year later; rate of disc, muscle and ligament infection (primary outcome); diabetes and corticoid use (confoundings). METHODS: The protruded disc, muscle and ligament samples were sent for culture analysis in up to 30 minutes. A subsample of 17 patients underwent next-generation sequencing (NGS) molecular analysis too. We performed descriptive analysis and comparison of groups of patients with and without infection or contamination using Student's t, Mann-Whitney, chi-square, or Fisher's exact tests as appropriate, and pre- and postsurgical comparisons with the Wilcoxon test. RESULTS: From January 2018 to September 2019, 112 patients underwent open lumbar microdiscectomy, 67 (59.8%) men. Cultures showed 7 (6.3%) positive cases in the disc (2 with C. acnes), 3 (2.7%) in the ligament, and 12 (10, 7%) in muscle. No evidence of a difference in Modic alterations pre- or postoperatively was found between patients with and without positive culture 1 year after surgery. No association was found between culture positivity and functional or pain differences either. NGS results were all negative for C. acnes. CONCLUSIONS: We identified infective bacterial presence in the herniated disc in less than 2% of patients with disc herniation. C. acnes was not identified in any disc microbiome analysis. No significant association was observed between positivity for tissue infection and any clinical prognostic factor.

Evaluation of ulnar variance on wrist MR imaging: is it a reliable measure?

OBJECTIVE: To determine if ulnar variance can be evaluated by magnetic resonance (MR) imaging and if this measure can be used as a reliable indicator when correlated to the gold standard technique, conventional radiography (CR). MATERIALS AND METHODS: From January to July 2018, the MR images of 64 participants, comprising 66 wrists (mean age 34.9 years; 33 females; 31 males), were obtained. Among those, 29 were referred for evaluation of the wrist for different medical reasons and 35 were asymptomatic volunteers from our radiology group. All subjects had a plain radiography of the wrist in a posteroanterior view with a mean interval between images of 1 day. Local ethics committee approved the study and written informed consent was obtained from all patients. Two musculoskeletal radiologists evaluated the images. Correlation coefficients and a linear regression model were used for statistical analyses. RESULTS: Intra- and inter-observer analyses were performed for both diagnostic methods with results showing concordance (intra-observer: kappa score: MR 0.915/CR 0.931; p < 0.05; inter-observer: kappa score: MR 0.857/CR 0.931; p < 0.05). The intraclass correlations of MR and CR to evaluate agreement between the radiologists was slightly higher for radiologist #1 (0.771) than for radiologist #2 (0.659). A linear regression model showed good model fit indicating that MR does correlate with the ulnar variance as measured by CR (CR = 0.554 + 0.897 × MR, R2 = 0.665). CONCLUSION: Although CR is the gold standard method for the evaluation of ulnar variance, our study demonstrated that MR can be used as a reliable qualitative option.

Are the osseous and tendinous-cartilaginous tibial tuberosity-trochlear groove distances the same on CT and MRI?

OBJECTIVE: To verify whether the tibial tuberosity-trochlear groove distance (TT-TG) and the tendinous-cartilaginous TT-TG (the distance between the patellar tendon and trochlear groove: PT-TG) are identical using computed tomography (CT) and magnetic resonance imaging (MRI) techniques. SUBJECTS AND METHODS: The TT-TG and PT-TG distances were measured on the same knee samples by three observers (two measurements per observer) using CT and MRI scans collected retrospectively. The reproducibility of the measurements was assessed using the interclass correlation coefficient (ICC). The means and standard deviations of four measurements were calculated for each patient. A paired t-test was used to assess differences between measurements. RESULTS: Fifty knee samples (32 with patellar instability and 18 with other conditions) were evaluated. The inter- and intraobserver reliability was excellent for all four measurements (>0.8). On average, the TT-TG distance on MRI was 3.1-3.6 mm smaller than that on CT, and the PT-TG distance on MRI was 1.0-3.4 mm larger than the TT-TG distance on MRI. CONCLUSION: The osseous TT-TG and tendinous-cartilaginous PT-TG distances determined by CT and MRI were not identical.