Mechanical force enhanced bony formation in defect implanted with calcium sulphate cement

To improve the osteogenic property of bone repairing materials and to accelerate bone healing are major tasks in bone biomaterials research. The objective of this study was to investigate if the mechanical force could be used to accelerate bone formation in a bony defect in vivo. The calcium sulfate cement was implanted into the left distal femoral epiphyses surgically in 16 rats. The half of rats were subjected to external mechanical force via treadmill exercise, the exercise started at day 7 postoperatively for 30 consecutive days and at a constant speed 8 m·min-1 for 45 min·day-1, while the rest served as a control. The rats were scanned four times longitudinally after surgery using microcomputed tomography and newly formed bone was evaluated. After sacrificing, the femurs had biomechanical test of three-point bending and histological analysis. The results showed that bone healing under mechanical force were better than the control with residual defect areas of 0.64±0.19 mm2 and 1.78±0.39 mm2（P〈0.001）, and the ultimate loads to failure under mechanical force were 69.56±4.74 N, stronger than the control with ultimate loads to failure of 59.17±7.48 N（P=0.039）. This suggests that the mechanical force might be used to improve new bone formation and potentially offer a clinical strategy to accelerate bone healing.

Varus ankle arthritis: a modified operation with a novel osteotomy and lateral hinge plate fixation technique

Ankle arthritis is a disease characterized by degeneration of articular cartilage,which is always accompanied with pain,decreased mobility,and varus deformity.Supramalleolar osteotomy is a reliable techniques in the treatment of arthritis.It can correct deformities at the distal tibia and normalize the load-bearing axis,and thereby reduce the unusual compression to the articular cartilage,alleviate pain,and improve functionality.The shortcomings include the frequent intra-operative fluoroscopy and no early exercise or weight-bearing.What is more,in the process of distracting the tibia after osteotomy,the separation of contralateral cortical bone often occurs.Takeuchi et al[1]reported that fracture and disruption of the lateral cortex would result in distinct instability to the osteotomy.Miller et al[2]noted that this complication contributed to the loss of angular correction,implant failure,delayed union even non-union of the osteotomy.In this study,we reported a modified osteotomy with a preshaped plate and novel osteotomy to overcome these shortcomings.

矫形外科研究中的分子生物力学

在过去的10-15年，分子生物力学成为矫形外科研究的一个新兴分支，其研究主要集中于骨骼-肌肉组织的细胞外基质（ECM）的分子结构，应用单个分子技术（或者纳米技术）测量和量化分子的力学性能。

A comparative study of the midfoot structure of humans and mice by CT measurement:Implications for employing a mouse model to study Lisfranc injury

Although midfoot injury,especilly Lisfranc sprain,is a relative rare traumatic pathology,if overlooked or treated incorrectly,the damage will develop into chronic Lisfranc injury,which is characterized by lifelong residual symptoms.The differences in injury severity,healing rates,treatment plans,and patient adherence make pro-spective investigations of the pathogenesis of Lisfranc injury very dificult to conduct.The development of ananimal model that mimics the symptoms of humans with chronic Lisfranc injury has the potential to lessen thechallenges associated with prospective human research.Previous research has successfully used a mouse model to explore the biomechanics of the human ankle joint.However,it remains to be determined if the mouse model canmimic human midfoot functions based on their similarities in anatomical structure.In this study,the anatomicalstructure of the mouse and human midfoot were compared by CT scan.The animal image data were obtainedfrom 10 male C57BL/6J mice(20 feet)by micro-CT.The human data were obtained from six volunteers(six feet)by CT scanning.The three-dimensional skeletal structure of the midfoot was reconstr ucted,and the morphologicalparameters were measured by a plane projection method.There were no significant differences among thehindfoot adductus angle(mice:28.86±6.27°;human:25.45±2.70°),metatarsus aductus angle(mice:11.34±2.95°;human:11.48±3.97°),or the transverse arch angle(mice:111.77±4.70°;human:111.84±6.34°)between the mice and humans.The mice had a comparable Lisfranc joint complex architecture compared tohumans in both coronal and transverse planes.The lateral cuneiform was fused with the navicular bone in mice,which would provide better intrinsic stability than in humans.Future research is necessary to evaluate the mouse midfoot injury model and the similarities of their neuro-musculo-skletal systems with humans.