Segmental mobility and intradiscal pressure were measured and the data compared in six cadaveric lumbar spine specimens before and after in vitro simulated single level L4-5 and double level L4-5-S1 anterior interbody fusions. The experimental objective was to study the biomechanical effects of single level L4-5 and double level L4-5-S1 anterior interbody fusions on the neighboring unfused segments. The relationship between the local rigidity created by fusion mass and accelerated degeneration reported at the neighboring unfused intervertebral discs is not clear. Six cadaveric lumbar spine specimens were biomechanically tested in flexion and extension. Segmental mobility and intradiscal pressure of the specimens were measured before and after in vitro simulation of single level L4-5 and double level L4-5-S1 anterior interbody fusions. The mobility of the motion segments immediately above and below an L4-5 fusion was increased in flexion. When the L5-S1 segment was also fused, the loss of segmental motion in both flexion and extension at the L4-5 and L5-S1 were compensated for by increased motion in all levels above the fusion. In both flexion and extension, the intradiscal pressures of all unfused intervertebral discs were increased after a single level L4-5 fusion and this increase was even more marked after a double level L4-5-S1 fusion. There is no evidence that the neighboring unfused segments are loaded beyond their physiological limits due to the fusion. However, the neighboring unfused segments have to work more frequently toward the extremes of their functional ranges of motion after fusion and these effects will be more marked after a double level L4-5-S1 fusion.

Concerns regarding the effects of load carriage have led to recommendations that backpacks be limited to 10 – 15% of body weight, based on significant changes in physical performance. However, gait responses to backpack loads are not entirely consistent and there is a particular lack of data regarding load-bearing gait in adolescent females. Gait patterns of 22 normal adolescent girls were recorded at backpack loads of 0, 7.5, 10.0, 12.5 and 15.0% body weight. Temporal-distance, ground reaction force and joint kinematic, moment and power parameters were analysed by repeated measures ANOVA with factors of backpack load and side (left or right). Walking speed and cadence decreased significantly with increasing backpack load, while double support time increased. Kinematic changes were most marked at the proximal joints, with a decreased pelvic motion but a significant increase in the hip sagittal plane motion. Increased moments and power at the hip, knee and ankle showed increasing demand with backpack load. Parameters showed different responses to increasing load, and those that suggested a critical load indicated this to be approximately 10% body weight. While this may be due to a change in gait due to increased demand, further work is required to verify this and also to examine the cumulative effects of backpack load on the musculoskeletal system, which may be more appropriate in determining recommended load limits.

Background and purpose:  Naringin, a flavanone glycoside in citrus fruits, has been recently reported to stimulate bone formation in vitro and in vivo. The present study was designed to determine if naringin could exert oestrogen‐like protective actions in bone.Experimental approach:  Young C57/BL6J mice were ovariectomized (OVX) and treated orally with naringin (0.2 or 0.4 mg·g⁻¹·day⁻¹), 17β‐oestradiol (2 µg·g⁻¹·day⁻¹) or its vehicle for 6 weeks. Bone mineral densities (BMD) and polar stress‐strain index (SSI) were measured by peripheral quantitative computed tomography. Rat osteoblast‐like UMR‐106 cells were co‐incubated with the oestrogen receptor (ER) antagonist ICI 182780 to determine if the effects of naringin on osteoblastic functions were ER dependent. Functional transactivation of ERα and ERβ as well as ERα phosphorylation by naringin were also studied.Key results:  Naringin at 0.4 mg·g⁻¹·day⁻¹ increased BMD at trabecular‐rich bone in OVX mice. Naringin (at both doses) significantly increased SSI at distal femur and lumbar spine and increased biomechanical strength (ultimate load and energy for breaking) at tibia diaphysis in OVX mice. The stimulatory effects of naringin on osteoblastic functions could be abolished by co‐incubation with ICI 182780 in UMR‐106 cells. Naringin failed to stimulate ERα‐ or ERβ‐mediated oestrogen response element‐dependent luciferase activity but could significantly induce ERα phosphorylation at serine 118, in UMR‐106 cells.Conclusions and implications:  Naringin was effective in protecting against OVX‐induced bone loss in mice and its actions might be mediated through ligand‐independent activation of ER in osteoblastic cells.

A prospective study on the comparison of the clinical efficacy and patient's acceptance of the 2 orthotic management methods. To compare the treatment effectiveness and patients' acceptance of the flexible spinal orthosis, SpineCor with that of the rigid spinal orthosis for the patients with moderate adolescent idiopathic scoliosis. The patients' acceptance to the rigid spinal orthoses is always a concern as it could greatly affect the clinical outcome. SpineCor is a relatively new design for tackling those inevitable drawbacks found in rigid orthosis. However, there was no study to compare this design with the conventional method regarding their treatment efficacy and the patient's acceptance. Forty-three subjects with moderate adolescent idiopathic scoliosis were randomly assigned to the SpineCor group (S group, n = 22) and rigid orthosis group (R group, n = 21). Their survival rate in the first 45 months of intervention was studied. The subjects' acceptance to the orthoses was evaluated by a purpose-designed questionnaire, which was administered in the 3rd, 9th, and 18th months of intervention. In the study period, there were 68% of the subjects in the S group and 95% of the subjects in the R group did not show curve progression. Significant difference (P = 0.046, by Fisher exact test) in failure rate between the 2 subject groups was found although the 2 groups had similar responses to the questionnaire. The current study showed that the failure rate of the SpineCor was significantly higher than that of the rigid spinal orthosis, and the patients' acceptance to the SpineCor was comparable to the conventional rigid spinal orthosis.