ObjectiveTo analyze the relationship between the bone mineral density (BMD) and lumbar intervertebral disc degeneration in rhesus macaques by using T1ρ-MRI. MethodsTwenty female rhesus macaques at the age of 10.9 years on average (rang, 4-20 years) were selected. The lumbar intervertebral discs were classified by Pfirrmann grading system and the T1ρ relaxation time (T1ρ value) was examined by using MRI (Philips 1.5 Tesla), and then BMD values of the L4,5 vertebrae and femoral ward's triangle were detected by using Osteocore dual energy X-ray absorptiometry. Finally, the relationship of T1ρ value of the lumbar intervertebral discs and Pfirrmann grading with age, weight, BMD of lumbar vertebrae and femoral ward's triangle was analyzed. ResultsThe BMD values of lumbar vertebrae and femoral ward's triangle were (0.64±0.17) g/cm2 and (0.67±0.19) g/cm2 respectively, showing no significant difference (t=2.893, P=0.128). According to Pfirrmann grading system, there were 7 cases of grade I, 8 cases of grade Ⅱ, and 5 cases of grade Ⅲ at L4,5 intervertebral discs. The T1ρ value of the lumbar intervertebral disc was (104.08±18.65) ms; the T1ρ values of grades I, Ⅱ, and Ⅲ were (121.31±13.44), (104.73±15.01), and (77.41±11.87) ms, respectively. There was a negative correlation between T1ρ value and the age and the BMD of lumbar vertebrae and femoral ward's triangle. There was a positive correlation between Pfirrmann grading and the variables as listed above. Significant negative linear correlation was also observed between T1ρ value and Pfirrmann grading. ConclusionThe T1ρ value is a reliable index when quantifying lumbar intervertebral disc degeneration, and there is a significant positive correlation between BMD and lumbar intervertebral disc degeneration in rhesus macaques.
ObjectiveTo establish the degenerative disc animal model in rhesus macaques and to verify its reliability with T1ρ, spin-lock imaging and T2-mapping MRI and histological observation. MethodsTwelve female rhesus macaques (aged 4-6 years, weighing 4.4-6.1 kg) were enrolled in the study. The L5, 6 intervertebral disk was used for the experimental group by injecting 1 mL bleomycin A5 (2 mg/mL) to its adjacent endplates to induce degeneration, and the L4,5 intervertebral disk for the control group by injecting 1 mL normal sodium to its adjacent endplates. T1ρ and T2-mapping relaxation time was examined by using MRI, and the histological observation was performed to evaluate the process of degeneration at 1, 4, and 12 weeks after operation. ResultsThere was no significant change of T1ρ, T2 map relaxation time in the control group at different time points before and after operation (P>0.05). In the experimental group, there was a significant decrease of T1ρ relaxation time from 4 weeks after operation, showing significant difference when compared with the values at pre-operation and 1 week after operation (P<0.05). The T2 map relaxation time decreased significantly at 12 weeks after operation, showing significant difference when compared with the values at the other time points (P<0.05). There was no significant difference between 2 groups at the other time points (P>0.05) except T1ρ relaxation time at 4 and 12 weeks and T2 map relaxation time at 12 weeks (P<0.05). No significant change of the percentage of the high intensity area of the operated discs was observed on T2WI of MRI after operation in 2 groups (P>0.05). The histological results showed that the number of nucleus pulposus decreased and arranged irregularly at 4 weeks, and there were fibrosis changes of nucleus pulposus and cleft of the inner annulus fibrosus at 12 weeks after operation in the experimental group. ConclusionDegeneration of lumbar intervertebral disc in rhesus macaques can be induced by injecting bleomycin A5. T1ρ-MRI may be an effective method to evaluate early degeneration of intervertebral disc.
ObjectiveTo investigate the effect of body mass index (BMI) on the outcome of posterior 360° fusion for single-level lumbar degenerative diseases. MethodsA retrospective study was carried on 302 cases of singlelevel lumbar degenerative diseases treated with posterior 360° fusion between September 2009 and September 2013. All patients were divided into 3 groups according to BMI: normal weight (BMI<24 kg/m2) in 105 cases (group A), overweight (24 kg/m2≤BMI< 28 kg/m2) in 108 cases (group B), and obese (BMI≥28 kg/m2) in 89 cases (group C). There was no significant difference in gender, age, disease duration, disease patterns, affected segments, preoperative Japanese Orthopaedic Association (JOA) score and Oswestry disability index (ODI) among 3 groups (P>0.05). The operation time, intraoperative blood loss, postoperative hospital stay, and complications were recorded. The lumbar function was assessed by JOA score and ODI at pre- and post-operation (at 3, 6, and 24 months). ResultsThe operation time, intraoperative blood loss, and postoperative hospital stay of group C were significantly more than those of groups A and B (P<0.05), but no significant difference was found between group A and group B (P>0.05). The patients were followed up 24-45 months. Postoperative JOA score and ODI showed significant improvements in each group when compared with preoperative ones (P<0.05), but there was no significant difference among groups at each time point after operation (P>0.05). There was no significant difference in the incidence of total complications among 3 groups (χ2=3.288, P=0.193). The incidence of incision-related complications (infection and poor healing) in group C was significantly higher than that of groups A and B (P<0.05), but no significant difference was shown between group A and group B (P>0.05). However, there was no significant difference in cerebrospinal fluid leak, pseudarthrosis formation, and revision among 3 groups (P>0.05). ConclusionPosterior 360° fusion for single-level lumbar degenerative diseases can obtain good effectiveness in patients with different BMI, but patients whose BMI was ≥28 kg/m2 have longer operation time, more intraoperative blood loss, longer hospital stay, and higher incidence of postoperative incision-related complications.