Psoas major and lumbar lordosis may correlate with pain episodes during Sorensen test in patients with non-specific low back pain.

BACKGROUND: The reason that participants develop pain episodes during the Sorensen test remains unclear. Lumbar lordosis and trunk muscle are important for dynamic stability of the spine; however, their role in pain episodes during the Sorensen test has not yet been discussed. OBJECTIVE: To investigate the effects of muscular morphology and lumbar curvature on pain development during the Sorensen test in patients with non-specific low back pain (LBP). METHODS: Ninety-one patients diagnosed with chronic non-specific LBP and underwent the Sorensen test were enrolled. Lumbar lordosis, cross-sectional area and fat infiltration rate of trunk muscle and centroid line of psoas major (dividing into three types: anterior arc, linear and posterior arc) were measured using ImageJ software. All recruited patients were grouped into pain episode and exhaustion groups and were matched for the confounders based on propensity scores. The above parameters were compared between groups and further adjusted for confounding bias. RESULTS: After adjustment , the mean differences in lumbar lordosis of 12.1 ± 2.3∘ between the two groups in the complete cohort and of 13.9 ± 2.5∘ in the matching cohort remained significant, the exhaustion group had a 0.22-fold and 0.08-fold risk of presenting as linear and posterior arc types, respectively, compared with the pain episode group in the complete cohort (p= 0.008, p= 0.004), the corresponding values were 0.19-fold and 0.05-fold, respectively, in the matching cohort (p= 0.014, p= 0.010). Logistic regression demonstrated that lumbar lordosis, the linear and posterior arc types were significantly associated with pain episode during the test (OR = 0.78, p< 0.001; OR = 4.50, p= 0.038; OR = 9.93, p= 0.033). CONCLUSIONS: Lower lumbar lordosis and linear and posterior arc types of the psoas major centroid line were possibly relevant to the pain episode during Sorensen test in patients with chronic non-specific LBP.

Preparation and properties of α-calcium sulphate hemihydrate and ß-tricalcium phosphate bone substitute.

Autogenous bone graft carries the risk of complications. In contrast, artificial bone graft provides initial strength and allows new bone ingrowth. In this study, we examined methods of preparation of α-calcium sulphate hemihydrate (α-CSH) and ß-tricalcium phosphate (ß-TCP), and a composite of the two materials. Characterization of the materials was determined with X-ray diffraction, differential thermal analysis (DTA), scanning electron microscopy (SEM), and porosity analysis. ß-TCP exhibited the spatial structure and porosity of normal bone with a macropore size of 50-400 µm and some 1 µm micropores. α-CSH exhibited a regular crystal structure. A combined material was prepared in a 1:1 weight ratio, and in a rabbit model, the rate of new bone mineralization was similar to that of autogenous bone graft. The combined material of ß-TCP and α-CSH in this study may provide similar efficacy as autogenous bone graft.

Investigation of the histology and interfacial bonding between carbonated hydroxyapatite cement and bone.

An ideal bone implant should facilitate the formation of a new bone layer as an osteo-integrated interface between bone and the implanted biomaterials. In the present work, the interface between carbonated hydroxyapatite (CHA) cement and bone was evaluated by interfacial bonding strength measurements and histological characterizations. CHA cement was implanted into a mongrel dog's femoral supracondylar and below the tibial plateau area, and was then tested ex vivo by, respectively, detaching and pullout experiments. Polymethylmethacrylate (PMMA) was used as a control. CHA cement could be directly injected and solidified in situ to repair bone defects. Histology results showed that CHA bonded with bone through gradual remodeling and was replaced by new bone tissue, which is an attribute for excellent biocompatibility. The interfacial bonding strength increased with implantation time. After 16 weeks implantation, the measured detaching force and the pullout force between CHA and bone were 281 +/- 16 N and 512.5 +/- 14.5 N, respectively. These values were several times higher compared to 5 days implantation. In contrast, the control showed a fibrous microstructure between PMMA and bone, and the detaching force and the pullout force decreased with implantation time. The results strongly suggest that CHA can form a better osteo-integrated interface compared to PMMA, and could be used as an ideal biomaterial for bone defect repair.

[A special type of discogenic low back pain: normal signal intensity of magnetic resonance imaging with abnormal discography].

OBJECTIVE: To report a group of special patients showing a normal signal intensity of MRI with a positive discography and discuss its pathogenesis and clinical significance. METHODS: From August 2003 to November 2008, 288 patients with chronic low back pain were treated. Of these patients, 12 showed a normal intensity signal of MRI in lumbar intervertebral discs with a positive discography. There were 7 males and 5 females aged 20 - 44 years with an average of 29.6 years. The duration of disease was 8 months to 3 years with an average of 1.8 years. Dallas CT grading method was used for assessing the degree of annular disruption. RESULTS: Of these 12 patients, 33 lumbar discs underwent discography. Twelve discs in 12 patients showed annular disruption and low back pain reproduction. Among 12 painful discs, 3 showed grade 2 annular disruption and 9 showed grade 3 annular disruption. CONCLUSION: Patients who are refractory to conservative care and have normal signal intensity in lumbar disc MRI and who are suggested as discogenic origin and might need further treatment such as minimal invasive surgery or lumbar interbody fusion should still be examined by discography.

[Natural history and prognosis of discogenic low back pain].

OBJECTIVE: To understand the natural history and prognosis of patients with discogenic low back pain so as to offer a better guide on its clinical treatment. METHODS: From December 2003 to November 2004, we consecutively hospitalized 72 patients with discogenic low back pain diagnosed by lumbar discography. These patients were randomized into two groups. One group (n = 36) received an intradiscal methylene blue (MB) injection immediately after discography while another group (n = 36) received a placebo. Both Visual Analog Scale (VAS) and Oswestry Disability Index (ODI) were used to assess the back pain symptoms and the lumbar function respectively during a 4-year follow-up period. RESULTS: In total, 32 of 36 patients who received a placebo injection underwent a 4-year follow-up. Of these patients, 4 cases (12.5%) had their low back pain symptoms alleviated, 1 case (3.1%) slightly improved, 3 cases (9.4%) aggravated and 22 cases (68.8%) had no change in symptoms. According to VAS and ODI scores taken at different time points, these two scores gradually decreased over time; however, no statistical significances were found (VAS: F = 3.049, P > 0.05; ODI: F = 2. 272, P > 0.05). CONCLUSION: The disease course of discogenic low back pain is chronic and persistent so that its symptoms show no improvement over time.