To these and to such other objects as may hereinafter appear, the present invention relates to fracture cast braces and, more particularly, to a head plate for a hinge brace for a fracture cast, as described in the following specification and recited in the annexed claims, taken together with the accompanying drawings, wherein like numerals refer to like parts, and in which:
FIG. 1 is a plan view of a hinge brace showing various modifications;
FIG. 2 is a cross-section along the line II--II in FIG. 1 before assembly of parts;
FIG. 3 is a cross-section along the line II--II in FIG. 1 after assembly of parts;
FIG. 4 is a view along the line V--V in FIG. 1;
FIG. 5 is a view similar to FIG. 3 of a further modification; and
FIG. 6 is a cross-sectional view of an embodiment of the head plate of the present invention illustrating the parallel grooves.
Referring now to FIG. 1, there is shown a hinge-brace for a fracture cast. The brace comprises a polycentric hinge portion 1 which may, for example, be made of polyethylene and can be moulded or formed from polyethylene bar. At each end, the hinge portion 1 is secured to a head plate 2 and various head plate modifications and methods of securing are shown in the drawings.
The bottom half of FIG. 1 shows a head plate 2, integrally moulded with the hinge portion 1 while the upper half of FIG. 1 shows a separately made head plate subsequently secured to the hinge portion.
The hinge portion 1 is of generally conventional shape and may have its major portion displaced out of the plane of the paper to prevent the brace, when in use, from rubbing against the condyles of a joint, (c.f. FIG. 4).
The head plate 2, however, differs considerably from the head plates of previously used hinge braces. As clearly shown in FIGS. 2, 3, and 5, the head plate 2 is crescent-shaped or arcuate in cross-section, being thicker in its central portion and thinner at the periphery. Furthermore, the head plate and hinge portion are secured together in a substantially flush manner so as to form continuous, uninterrupted bonding surfaces to avoid the possibility of a dead space forming when the brace is used.
The head plate shown in FIGS. 2 to 4 is formed with a recess 3, opening on the surface of the head plate, in which are formed two upstanding stakes, stubs, or protrusions 4. The end 5 of the hinge portion 1 is formed with two holes 6 to receive the stakes 4 and has a thickness substantially equal to the depth of the recess so that, as shown in FIGS. 3 and 4, the end 5 of the hinge portion can be received in a substantially flush manner in the recess 3. The free ends of the stakes 4 are then compressed in a press using a spinning die which both swages and welds them down onto and partly into the hinge portion, as shown at 7, thereby securing the hinge portion to the head plate.
In the modification shown in FIG. 5, the head plate is formed with a central hole 8, opening on the side of the head plate, to receive an appropriately shaped end of the hinge portion 1. If desired, adhesive or glue may be used to reinforce the connection between the head plate and the hinge portion. Other forms of fixing the head plate to the hinge portion are possible, including rivets, snap-on fixings, or adhesive fixings, provided that in each case the substantially flush fitting of the two parts is achieved.
The use of a hinge brace, as just described, is substantially the same as that of previously proposed braces. However, the arcuate cross-section of the head plate provides close conformation with a limb and this conformation, together with the elimination of dead space due to the flush connection of the head plates and hinge portion, ensure good lamination of the head plates using modern resin casting materials.
In order to improve the lamination, the head plates may be roughened or formed with teeth or splines 9 as shown at the bottom right hand side of FIG. 1 and in FIG. 1A. The teeth or splines 9 may be formed on one or both sides of the head plate and may point in any direction, or, as shown, some may point in one direction and some in another.
The head plates may be formed with holes 10 spaced from the central portion, as is conventional, but in order to enhance bonding and to reinforce the benefits of using a curved and shaped head plate, circular pieces of the casting material may be provided with the brace to fill the holes and link the underlying and overlying layers of casting fabric material.
FIG. 6 illustrates a modified form of the head plate wherein parallel spaced grooves 12, located on either side of the central portion, are provided on the exterior surface such that the peripheral portions 14 of the head plate are articulately or hingeably joined to the central portion and can bend relative thereto. Grooves 12 are remote from the junction of the hinge portion and the head plate and permit the head plate to more easily accommodate the contours of the limb to which the cast is applied. Prongs or projections 16 may be used on the exterior surface of the head plate proximate the grooves 12 to provide improved mechanical capture of the casting material, if desired.
While the grooves 12 do represent dead spaces which are normally to be avoided, the placement of the grooves and the use of the prongs 16 largely negate any deleterious effects which may occur due to the incorporation of the grooves and, in addition, the better fit provided by bending along the grooves tends to eliminate dead spaces which would otherwise exist between the peripheral portions of the head plate and the limb of the patient.
As indicated above, a previously proposed hinge brace is in the form of a thin rectangular head plate to which the end of a hinge portion is rivetted and, thus, stands up proud above the head plate. In contradistinction, the head plate of the present hinge brace has a central portion which is at least as thick as the end of the hinge portion to enable a flush fitting arrangement of the head plate and hinge portion to be achieved, thereby eliminating dead spaces and considerably improving lamination.
The present invention makes it possible to design the head plate so that it will be thinner at its thickest central portion than the thickness of a comparable previously proposed hinge brace.
Furthermore, due to the improved lamination which can be achieved with the present hinge brace, the bond strengths which can be obtained using modern resin casting materials may equal or surpass those which can be obtained using Plaster of Paris, which may, itself, of course, be used with the present hinge brace.
The present hinge brace head plate may be formed in any suitable material, including metal, as an alternative to plastic and head plates of either material may be combined with metal monocentric or plastic polycentric hinges or with any other orthopaedic device which requires incorporation into casts. These include plastic shoe inserts, hinged ankle joint preformed fracture braces, and preformed femoral fracture bracing kits, amongst others.
While only a limited number of preferred embodiments of the present invention have been disclosed herein for purposes of illustration, it is obvious that many variations and modifications could be made thereto. It is intended to cover all of these modifications and variations which fall within the scope of the present invention, as defined by the following claims.