Comparison of spring ankle braces versus splints and casts in treating ankle sprains in patients diagnosed with ankle sprains.

BACKGROUND: Various treatment approaches for individuals with ankle sprains can reduce treatment costs and enhance recovery. This study aimed to compare the efficacy of spring ankle braces with splints and casts in treating ankle sprains. MATERIALS AND METHODS: This cross-sectional study involved 60 patients diagnosed with ankle sprains at the orthopedic clinic of Imam Khomeini Hospital in Jiroft in 2022. Following diagnosis confirmation through additional examinations and imaging, patients with ankle sprains not requiring surgery were selected and placed in two groups: one treated with spring ankle braces and the other with splints or casts. Both groups underwent a 4-week treatment regimen, comprising 30 individuals each. Data were collected and analyzed using SPSS version 26. RESULTS: The average age of patients was 32.5 ± 13.4 years. Of the ankle sprain patients, 56.7% were male. Patients reported the highest satisfaction levels with the plaster cast treatment method. A statistically significant relationship was found between patient satisfaction and the treatment methods of spring ankle braces and plaster casting (P < 0.05). Patients treated with plaster casts reported the lowest pain levels, with a significant relationship between pain levels and the two treatment methods (P < 0.05). Range of motion results were similar for both treatment methods, while the cast treatment showed the highest incidence of skin complications. A significant relationship was observed between spring ankle braces and plaster casts regarding skin complications (P < 0.05). CONCLUSION: Treating ankle sprains with plaster casts leads to higher satisfaction and lower pain levels compared to using spring ankle braces.

Soft skeletons transmit force with variable gearing.

A hydrostatic skeleton allows a soft body to transmit muscular force via internal pressure. A human's tongue, an octopus' arm and a nematode's body illustrate the pervasive presence of hydrostatic skeletons among animals, which has inspired the design of soft engineered actuators. However, there is a need for a theoretical basis for understanding how hydrostatic skeletons apply mechanical work. We therefore modeled the shape change and mechanics of natural and engineered hydrostatic skeletons to determine their mechanical advantage (MA) and displacement advantage (DA). These models apply to a variety of biological structures, but we explicitly consider the tube feet of a sea star and the body segments of an earthworm, and contrast them with a hydraulic press and a McKibben actuator. A helical winding of stiff, elastic fibers around these soft actuators plays a critical role in their mechanics by maintaining a cylindrical shape, distributing forces throughout the structure and storing elastic energy. In contrast to a single-joint lever system, soft hydrostats exhibit variable gearing with changes in MA generated by deformation in the skeleton. We found that this gearing is affected by the transmission efficiency of mechanical work (MA×DA) or, equivalently, the ratio of output to input work. The transmission efficiency changes with the capacity to store elastic energy within helically wrapped fibers or associated musculature. This modeling offers a conceptual basis for understanding the relationship between the morphology of hydrostatic skeletons and their mechanical performance.

Sea star inspired crawling and bouncing.

The oral surface of sea stars is lined with arrays of tube feet that enable them to achieve highly controlled locomotion on various terrains. The activity of the tube feet is orchestrated by a nervous system that is distributed throughout the body without a central brain. How such a distributed nervous system produces a coordinated locomotion is yet to be understood. We develop mathematical models of the biomechanics of the tube feet and the sea star body. In the model, the feet are coupled mechanically through their structural connection to a rigid body. We formulate hierarchical control laws that capture salient features of the sea star nervous system. Namely, at the tube foot level, the power and recovery strokes follow a state-dependent feedback controller. At the system level, a directionality command is communicated through the nervous system to all tube feet. We study the locomotion gaits afforded by this hierarchical control model. We find that these minimally coupled tube feet coordinate to generate robust forward locomotion, reminiscent of the crawling motion of sea stars, on various terrains and for heterogeneous tube feet parameters and initial conditions. Our model also predicts a transition from crawling to bouncing consistently with recent experiments. We conclude by commenting on the implications of these findings for understanding the neuromechanics of sea stars and their potential application to autonomous robotic systems.