This invention relates to devices for immobilizing a portion of the human body, and is particularly concerned with the provision of a device for supporting, restraining and/or immobilizing a portion of the body of a fracture victim or medical patient for reducing or minimizing injury to the individual by reducing freedom of movement prior to full medical procedures, during emergency transport, while conducting radiography, therapy, or surgery, or during recuperation.
Immobilizers and support structures for various body members are highly useful in many situations, particularly in the fields of medicine and therapeutic treatment of human patients. Thus, needs have existed for improved forms of temporary splints and restraining devices for transporting emergency accident victims to places of treatment while immobilizing affected portions of the victim's body to avoid further injury and minimize the effects of injuries already inflicted. Many rigid, semirigid and rigidifiable structures are known and used for these purposes, but all suffer from disadvantages in terms of weight, adaptability to different uses, and ease of employment.
Immobilizer devices should preferably be light in weight and capable of quick and convenient support for the body member being immobilized. Uses include arm or leg immobilizers, for example, for supporting a fractured limb in an immobilized and relatively comfortable position, radiological immobilizers for positioning the body during various radiologic procedures, head and neck immobilizers for use during surgery or in case of head, neck or upper body injury.
Immobilizer devices useful for the purposes noted above should have certain important features or characteristics in addition to light weight. They preferably should be readily conformed to the limb or portion of the body to be supported, regardless of the region at which applied and the attitude of the body structure in that region. The surface of the immobilizer that contacts the individual should snugly follow the body contour, but should not chafe or abrade the user and should also not present a hard surface. Further, the materials used should also be strong and durable, resistant to chemicals such as gasoline and oils encountered during accidents, and able to withstand rough handling prior to use, during application, and while applied.
Illustrative of immobilizer devices which are convertible from a collapsed to a rigidified condition are the devices disclosed in U.S. Pat. Nos. 3,212,497 to Dickinson, 3,745,998 to Rose and 3,762,404 to Sakita. U.S. Pat. No. 3,212,497 was apparently the earliest suggestion of such a collapsible system, and is based upon the use of an outer flexible bag and an inner woven but relatively non-stretchable bag which contains very fine polystyrene crystals. This arrangement undoubtedly proved to be too heavy (the example given is of a 3'.times.1' bag with 9 lbs. of crystal), and was surely not well adapted for use in emergency situations. U.S. Pat. Nos. 3,745,998 and 3,762,404 were relatively contemporaneous with each other, but the former contains a substantial number of advantageous features relative to the latter. It proposes the usage of a bag of flexible sheet material with internal lightweight polymer beads, the bag in one form being trapezoidal in form and secured by flexible strips upon an arm or other limb. The basic premise is that the beads, although being of formed particles, may be manipulated within the bag to be positioned for best conformity and support, with the detachable straps holding the bag in position, so that the bag may then be evacuated through a non-deformable spring-loaded valve of the type typically used for air-inflated tires. The valves are coupled into the interior of the enclosure by "distributor units" which protrude into the inner volume, so that the valves must be mounted in the side of the structure but the distributor substantially parallel to the surface to be supported. This arrangement is used to avoid the usage of the extra internal envelope of Dickinson U.S. Pat. No. 3,212,497. However, Rose also predicates his system upon the usage of a thin polyurethane film of between 0.002" and 0.014" thick to provide an elastic stretching and shrinking quality, with the beads having a relatively narrow range of bead densities falling between 1.00 and 2.00 lbs/ft.sup.3 and outside diameters ranging from 0.015" to 0.125", with a median particle size of 0.050", which is approximately 1.25 mm (the 0.125" diameter being approximately 3 mm). This relationship of small bead sizes to a shrinkable film envelope provides an arrangement in which the outer layer of filler particles may be engaged by the thin film envelope in a "shrinking, interfitting, pebbled embrace". Rose proposes many different forms of usage of this structure, including arm splints, arm slings, neck braces and stretchers, and the latter of which instances he proposes the use of a cushioning material on the surface.
Sakita U.S. Pat. No. 3,762,404 uses a flexible bag, employing an elastic material that may have a rubber mix, but also specifically has a frictional characteristic to prevent movement of the beads. Further to this end he employs internal partitions, and proposes the employment of soft valve constructions of a particular kind. In addition, he suggests that the suitable size range for the internal polymer beads is from 1 mm to 5 mm, using two materially different sizes within this range and with the specific gravities being from about 0.1 to about 0.6, meaning that the density is from about 6 to 36 lbs./ft.sup.3. This bag in practice is difficult to apply, difficult to conform to the proper position for the user, and cannot readily be made comfortable because of the inability of the internal beads to shift. In addition, the soft valve inevitably slowly leaks, losing the rigidity of the immobilizer even over a relatively short period of time.