Yang Yunfeng

Effect of the Plantar Fasciotomy on the Movement of the Foot Arch

Plantar fascia release has long been a mainstay in the surgical treatment of persistent heel pain, although its effects on the biomechanics of the foot are not well understood. The purpose of this study was to explore the role of the plantar fascia in the foot arch biomechanics, especially the fore foot motion after plantar fasciotomy via a three-dimensional finite element model of a normal left foot which comprising most joints of the foot. The validity of the three-dimensional finite element model was verified by cadaveric experiment. The vertical and horizontal displacement of the foot bones were calculated as well as the angulation under different situations. The height of the longitudinal arch decreased from 17.923 mm to 19.353 mm after the plantar fasciotomy in sagittal plane. The average contribution of the plantar fascia to the rotation of the foot bones were 34.53%, 22.46% and 12.63% in sagittal, transversal and coronal plane respectively. The plantar fascia is one of the major stabilizing structures of the longitudinal arch of human foot.

Inflammatory Regulation by Driving Microglial M2 Polarization: Neuroprotective Effects of Cannabinoid Receptor-2 Activation in Intracerebral Hemorrhage

The cannabinoid receptor-2 (CB2R) was initially thought to be the “peripheral cannabinoid receptor.” Recent studies, however, have documented CB2R expression in the brain in both glial and neuronal cells, and increasing evidence suggests an important role for CB2R in the central nervous system inflammatory response. Intracerebral hemorrhage (ICH), which occurs when a diseased cerebral vessel ruptures, accounts for 10–15% of all strokes. Although surgical techniques have significantly advanced in the past two decades, ICH continues to have a high mortality rate. The aim of this study was to investigate the therapeutic effects of CB2R stimulation in acute phase after experimental ICH in rats and its related mechanisms. Data showed that stimulation of CB2R using a selective agonist, JWH133, ameliorated brain edema, brain damage, and neuron death and improved neurobehavioral outcomes in acute phase after ICH. The neuroprotective effects were prevented by SR144528, a selective CB2R inhibitor. Additionally, JWH133 suppressed neuroinflammation and upregulated the expression of microglial M2-associated marker in both gene and protein level. Furthermore, the expression of phosphorylated cAMP-dependent protein kinase (pPKA) and its downstream effector, cAMP-response element binding protein (CREB), were facilitated. Knockdown of CREB significantly inversed the increase of M2 polarization in microglia, indicating that the JWH133-mediated anti-inflammatory effects are closely associated with PKA/CREB signaling pathway. These findings demonstrated that CB2R stimulation significantly protected the brain damage and suppressed neuroinflammation by promoting the acquisition of microglial M2 phenotype in acute stage after ICH. Taken together, this study provided mechanism insight into neuroprotective effects by CB2R stimulation after ICH.

The Displacements of Human Foot After Plantar Ligaments Injury: A Cadaveric Study and Finite Element Analysis

Most of the foot deformities relate to the arch collapse or instability, especially the longitudinal one. Though the function of the plantar fascia to the arch height has been investigated by some authors, the other plantar ligaments effect is still unclear. The purpose of this study was to explore the role of the plantar soft tissue in the foot arch biomechanics, including the plantar fascia, spring ligament complex, short plantar ligament and long plantar ligament through normal adult fresh frozen specimens in different injured condition. Also, a three-dimensional finite element model of a normal left foot was developed which was comprising most joints of the foot and consisted of bone segments, major ligaments and plantar soft tissue. These intrinsic ligaments of the foot arch were sectioned in different sequence in the cadaveric experiment, which simulated the different pathologic situation of the plantar ligaments injury to describe the bone segments displacement and stress distribution. The validity of the three-dimensional finite element model was verified by comparing results with experimentally measured data via the displacement and Von-mise stress of each bone segments. The flat foot model both in cadaveric foot and finite element foot was constructed and analyzed.

Experimental Measurement in Multi-Fields of Human Foot Under Simulated Body Weight Loading

It has been well studied that foot-ankle biomechanics plays an important role in body locomotion but still be far from well understanding, to some extent for lack of various biomechanical response information under physiological conditions. In this paper, seven unembalmed cadaver feet were loaded under controlled conditions simulating body weight, and biomechanical responses in multi-fields, such as displacement, strain and plantar pressure, were measured with material test machine, digital speckle correlation method (DSCM) measurement system, resistance strain gauge and F-Scan plantar pressure analysis system. Data gained from such multifields experimental measurement were precise and results were interpreted well. This research is aimed at fostering foot-ankle biomechanics well understanding and promoting further research with reasonable and comprehensive analysis.