Development of a standardized histopathology scoring system for intervertebral disc degeneration in rat models: An initiative of the ORS spine section

International audienceBackground:Rats are a widely accepted preclinical model for evaluating inter-vertebral disc (IVD) degeneration and regeneration. IVD morphology is commonlyassessed using histology, which forms the foundation for quantifying the state of IVDdegeneration. IVD degeneration severity is evaluated using different grading systemsthat focus on distinct degenerative features. A standard grading system would facili-tate more accurate comparison across laboratories and more robust comparisons ofdifferent models and interventions.Aims:This study aimed to develop a histology grading system to quantify IVD degen-eration for different rat models. Materials & Methods:This study involved a literature review, a survey of experts inthe field, and a validation study using 25 slides that were scored by 15 graders fromdifferent international institutes to determine inter- and intra-rater reliability.Results:A new IVD degeneration grading system was established and it consists ofeight significant degenerative features, including nucleus pulposus (NP) shape, NParea, NP cell number, NP cell morphology, annulus fibrosus (AF) lamellar organization,AF tears/fissures/disruptions, NP-AF border appearance, as well as endplate disrup-tions/microfractures and osteophyte/ossification. The validation study indicated thissystem was easily adopted, and able to discern different severities of degenerativechanges from different rat IVD degeneration models with high reproducibility forboth experienced and inexperienced graders. In addition, a widely-accepted protocolfor histological preparation of rat IVD samples based on the survey findings includeparaffin embedding, sagittal orientation, section thickness < 10μm, and staining usingH&E and/or SO/FG to facilitate comparison across laboratories.Conclusion:The proposed histological preparation protocol and grading system pro-vide a platform for more precise comparisons and more robust evaluation of rat IVDdegeneration models and interventions across laboratories

The efficacy of rhBMP-2 versus autograft for posterolateral lumbar spine fusion in elderly patients

Few studies have specifically examined the outcomes following rhBMP-2 usage in patients 65 years and older. The purpose of this retrospective study is to evaluate the efficacy of rhBMP-2 with allograft versus autograft for posterolateral lumbar fusion in patients 65 years and older. One hundred twenty-seven patients were divided into three groups based on fusion material and age. Subjects in group A (n = 34) consisted of patients 65 years and older who received rhBMP-2 and allograft. Group B (n = 52) was composed of patients under 65 years of age with rhBMP-2 and allograft. Subjects in group C (n = 41) were 65 years and older with autograft use. A comparison was made of fusion rate, fusion time (noticed, solid), clinical outcome, VAS, perioperative complications and revision rate between each group. The fusion rate and fusion time were similar in groups A and C; however, these were lower than that observed in group B. Clinical outcomes were similar amongst the groups. There were no significant differences in VAS and perioperative complication rate between groups A and C. In patients 65 years and older, rhBMP-2 with allograft may lead to acceptable fusion rates and fusion times, good clinical outcomes and reduced perioperative complications. The combination of rhBMP-2 with allograft yields equivalent outcomes as autograft in elderly patients undergoing instrumented posterolateral lumbar fusion. Additionally, when compared to patients under 65 years of age undergoing posterolateral lumbar fusion, the use of rhBMP-2 was not sufficient to overcome all aspects of the age-related weakened osteoinductive capacity encountered in elderly patients