RU2481807C2 - Orthopedic power element - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention relates to medical orthopedic equipment and can be used in extracorporal correctors of musculoskeletal system pathology. Orthopedic power element is made in form of curved wire construction from super-elastic alloy based on titanium nickelide with central section of active action and transmitting sections of extending from it arms. Wire construction is made from two adjacently located and mechanically connected wire rods from alloys with different, partly overlapping temperature intervals of super-elastic deformation.

EFFECT: invention ensures extension of interval of working temperature and area of device application, including work outside in cold and hot period of time.

3 cl, 3 dwg

Description

The invention relates to medical orthopedic equipment and can be used in extracorporeal correctors of the pathology of the musculoskeletal system.

The widespread pathology of the musculoskeletal system, leading to a decrease in the quality of life, and in severe cases to disability, is a problem of a social scale for patients, orthopedists and related services. Persistent deformities of the spine and extremities of congenital or acquired genesis are classified according to the severity of the disease, in accordance with which various treatment methods and technical means are used. In severe advanced forms of spinal curvature, widely invasive, often multi-stage surgical operations are used. In milder cases, mainly in childhood, external corrective devices are used.

The mechanical correction of the pathophysiological shape change of the skeleton is accompanied by the unloading of the gravitational stress of a given section. To do this, use orthopedic correctors (corsets, belts, collars). An important role that determines the technical and medical characteristics of corrective devices is played by power elements. They must develop the specified in magnitude and direction of effort, while possessing weight and overall characteristics that provide physical and cosmetic comfort for the patient in conditions of constant wearing of the corrector. Therefore, in the improvement of these devices, power elements are one of the main subjects of creativity of developers.

Known pneumatic power element used in a corset orthopedic device (Bardan A.I., Ryleev A.N. Orthopedic corset. Application for invention No. 96102498/14, A61F 5/02, 02/12/1996). It is made in the form of an inflatable tube made of elastic material. When filling with gas, it lengthens and connected by transmission elements with support rings of the medical corset causes the separation of the latter and, as a result, decompression of the spine. The device is inconvenient to use due to the large size and complexity of activation of pneumatic power elements.

Power elements using the deformation elasticity of metal rods are more compact (e.g. Petrushevsky II, Kanshievsky SM, Bondarenko IV Orthopedic corset. AS USSR No. 1724215). The disadvantage of devices, usually made of steel alloys, is rigidity and a short operating interval.

With respect to the aforementioned technical requirements, superelastic titanium nickelide has a noticeable advantage in the performance of power elements. A wide range of elastic deformation, approximating the specified material in mechanical properties to biological tissues, improves the efficiency of the action of power elements.

Known orthopedic power element of the spine curvature corrector (RF patent No. 22113544), made of nickel-titanium wire in the form of a meander-shaped flat spring. The action of this power element in the corrector differs from the action of the steel spring by a significantly larger working interval of deformation, in which a “soft” stress and uniformity develops. While in steel alloys, the reversible deformation resource is a fraction of a percent, in titanium-based alloys it reaches 6-8%. The disadvantage of this device is lateral deformation instability.

This disadvantage is minimized in another known construction of an orthopedic power element (Columbus V.T., Gunter E.E., Columbus E.V. Extracorporeal orthopedic distractor. Application for invention No. 2009143516, priority November 26, 2009, publ. Bulletin No. 15, 2011 Decision on the grant of a patent on September 2, 2011). It is made of a superelastic alloy based on titanium nickelide in the form of a curved wire structure with a central spring section of active action and transfer sections of the shoulders extending from it. By the greatest similarity of features, this device is selected as a prototype. The central section, formed in the form of a wound spring, provides, depending on the number and diameter of the turns, a dosed characteristic of the deformation resistance and the restoring force. The shoulder portions equipped with end loops for attaching to the elements of the orthopedic device not only transmit spring forces to these elements, but also themselves participate in the deformation and produce a return force.

The disadvantage of this device is a narrow range of operating temperatures, due to the physical properties of the nickel-titanium alloy. The TN-10 alloy used in medical structures is designed for contact with the patient’s body according to the temperature regime. The temperature range in which it exhibits a property of superelasticity, essential for the operation of the device, extends from +10 to + 60 ° C. In working conditions outside this interval, as is the case in extracorporeal correctors, especially on the street, in cold climates, this alloy loses its elasticity, and strength elements lose its working capacity. In this regard, the scope of use of the device is limited.

The technical result of the invention is the expansion of the operating temperature range and the field of use of the device.

The specified technical result is achieved in that the known orthopedic power element made of a superelastic alloy based on titanium nickelide in the form of a curved wire structure with a central spring section of the active action and the transfer sections of the shoulders extending from it, is characterized in that the wire structure is made of two adjacent and mechanically bonded wire rods of alloys with different, partially overlapping temperature ranges of superelastic deformation.

The achievement of the technical result is also ensured by the fact that the wire rods with different temperature ranges of superelasticity are mutually intertwined.

Preferred is the choice of temperature ranges for superelastic deformation of alloys in the ranges from -30 to +20 and from +10 to +60 degrees Celsius.

The relationship of the hallmarks with the implementation of the claimed technical result is confirmed by the following.

The expansion of the operating temperature range is due to the possibility of a targeted choice of temperature ranges in which titanium nickelide-based alloys exhibit a superelastic effect. The boundaries of the indicated temperature ranges are determined and regulated in the manufacture of alloys by the percentage of nickel. When two alloy samples are mechanically combined with different temperature ranges of superelasticity, the effect is realized in both intervals, and with partial overlap, in the continuous interval from the lower boundary of the lower interval to the upper boundary of the upper interval.

Mechanical alignment by grafting the wire elements provides tight mechanical contact in which either relative deformations or stresses are summed in individual sections depending on the orientation relative to the direction of bending. Due to the continuous alternation of such sections along the length of the winding, the averaged deformation characteristic of the wire composite demonstrates the effect of superelasticity over the entire total temperature range.

The choice of temperature ranges for the superelasticity of the two alloys in the ranges from -30 to +20 and from +10 to +60 degrees Celsius provides a total temperature interval sufficient to maintain the operability of the orthopedic power element in extracorporeal devices in various climatic zones, from cold to hot . The numerical values of the boundaries of the temperature ranges correspond to typical grades of nickel-titanium alloys.

The invention is illustrated by graphic illustrations of figures 1-3.

The orthopedic power element (Fig. 1) is made of a superelastic alloy based on titanium nickelide in the form of a curved wire structure with a central spring section of the active action 1 and transfer sections of the outgoing arms 2 with loop-like curls 3 at the free ends. The semi-finished wire product from which the structure is curved is formed by two interconnected wire rods made of titanium nickelide, differing in temperature ranges of superelasticity.

The operation of the device in various temperature ranges is illustrated in FIG. 2 by the graphs of the stress σ versus strain ε for various alloys, indicated by the numbers 1 (low temperature) and 2 (high temperature), constructed for the region of lower working temperatures (FIG. 2a) and upper working temperatures ( fig.2b).

In the region of low operating temperatures, alloy 1 exhibits the property of superelasticity and functions as such, and alloy 2 exhibits a relatively high elasticity that does not impede the functioning of the element of alloy 1. At high operating temperatures, alloy 2 exhibits the property of superelasticity and functions in this quality, however, the alloy 1 in this case exhibits a relatively low elasticity and, under certain conditions, impedes the functioning of an element of alloy 2. FIG. 3 shows stress-strain diagrams for personal orientation of the mechanical articulation of elementary sections of alloys 1 and 2 with respect to the applied force. If the force is applied to the parallel connected elements (figa), then the ordinates of the curves are summed up on the graph, and as a result, the articulated elementary section exhibits high elasticity, which quenches the effect of superelastic behavior. If a force is applied to series-connected elements (Fig. 3b), then the abscissas of the curves are summed on the graph, and as a result, the articulated elementary section remains super-elastic deformable. Thus, for the functioning of the device in the upper part of the operating temperature range, it is necessary to have zones of successive addition of forces. The best in this sense would be a wire material, formed by sections (disks) often alternating in length, of alloys 1 and 2, however, the formation of such a material would present an unjustifiably great technological complexity. Approximately the same effect is achieved when using two intertwined wire rods of alloys 1 and 2, the elementary sections of which turn out to be mechanically articulated in various orientations relative to the direction of deformation. Moreover, in such a mechanical composite, at any bends, there are always areas where deformations are summarized and the effect of superelasticity of alloy 2 is not quenched by the elasticity of alloy 1 (Fig. 3c).

The attainability of the claimed technical result was verified by laboratory measurements of the deformation characteristics of wire elements intertwined with each other, as well as full-scale tests of the thoracolumbar corset-distractor, designed for decompression of the spine. The corset is two bandage belts connected by orthopedic power elements made in accordance with the claimed technical solution. The strength elements, previously strained before fixing the bandage belts on the body, have a soft, constant distraction effect, leading to decompression of the interested part of the spine and stimulating the repair of damaged structures. The corset was used in home wear and in the field in the winter. The trouble-free operation of power elements in all modes confirms the claimed result: the expansion of the range of operating temperatures and, as a result, the expansion of the scope of the device.

The advantages realized by the claimed invention can be extended to a wide class of power elements, having a common feature, a pre-made alignment (lay) of two wire components into a semi-finished product, from which a power element of an arbitrary structure can be formed (curved).

Claims (3)

1. Orthopedic power element in the form of a curved wire structure made of superelastic alloy based on titanium nickelide with a central section of active action and transfer sections of the shoulders extending from it, characterized in that the wire structure is made of two adjacent and mechanically bonded alloy wire rods with varying, partially overlapping temperature ranges of superelastic deformation. 2. The orthopedic power element according to claim 1, characterized in that the wire rods with different temperature ranges of superelasticity are mutually intertwined. 3. The orthopedic power element according to claim 1, characterized in that the temperature ranges of superelastic deformation of the alloys are selected in the ranges from -30 to +20 and from +10 to + 60 ° C.

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