GB2304581A - Orthopaedic/orthotic bi-pivotal hinge - Google Patents

Abstract

The hinge, which may be part of an orthopaedic knee brace, comprises two hinge arms 14,16 and a hinge body having parallel front and back plates 18,20, the arms being independently mounted between the plates and secured thereto by pivotal securing means. Each hinge arm is adapted to extend and to flex, the amount of extension and flexion being limited by means of an insert stop 100 acting on each of the arms and in each of the directions of extension and flexion. The stop may have first and second pairs of angled stop faces for limiting extension and flexion at optionally different angles or may have body portions with concavely radiused sides symmetrically disposed about and tangential to a circle centred on the intersection of the vertical and horizontal axes of the stop.

Description

AN IMPROVED TRUE BI-PIVOTAL ORTHOPAEDIC AND ORTHOTIC HINGE WITH INCREMENTAL MOTION CONTROL ABSTRACT The hinge has optimally spaced pivots in which extension and flexion travel of each independently pivoted hinge arm is limited by a series of planar metal stops acting on both ams and in both directions. Each stop has first and second pairs of angled stop faces for limiting extension at optionally different angles and first and second pairs of angled stop faces for limiting flexion at optionally difirent angles. The hinge arms are disposed kanrten a front plate and a back plate and pivot means for each hinge arm also serve as securing means securing the plates and hinge arms together.Each stop is secured by a single screw which passes through one plate. Stops are mounted in the intemal flexion angle of the hinge.

FIELD OF THE INVENTION This inventnni relates to hinges employed in orthoses and orthopaedic braces used on the human body, particularly the knee joint In particular, the invent relates to no means for limiting the flexion and extension travel of the arms of a true bi-pivotal hinge.

BACKGROUND OF THE INVENTION AND THE PRIOR ART There art msny hinge designs used in orthopaedic splints and braces employed at the knee.

In a first widely used type, the are two hinge arms pined at and flowing about a single pivot This type is generally referred to by those skilled in the art as the uniqxial. uni-pivotal or monocentric type.

In a second type, perhaps even more widely used, there are two hinge arms each having its own pivot and also each having a set gear teeth about the periphery of the part which etnds between the pivots. The aims are so sized and arranged that the gear teeth mesh between the pivot points the- htegating the arm movements. Thus if one arm moves.

the other must move as well. This type is generally refereed to by those skilled in the art as the geared bi-axial, geared duocentric or geared polycentric type. The latter term is perhaps the most widely recognised.

Neither of these hinge types is nrmotely phys in the way they move and because their mechanical action is so unlike that of the human knee their use in a brace construct may be positively deleterious to an injured, repaired or deformed knee.

The term brace construct is used by those skilled in the art to describe the resuttard mechanical arrangement of a brace and the leg to which it is attached. A combination of casting materials (such as Plaster of Paris or resin impregnated bandages) and cast bracing hinges as well as braces secured on the leg by means such as straps are brace constructs once they are in place on the leg.

Mechanically, the knee is a modified, crossed, four bar linkage comprising the rigid elements femur, tibia and the anterior and the posterior cruciate ligaments. Its axis of rotation moves backwards or posteriorly as the knee is flexed from the fully extended position. The locus or track of the axis of knee rotation is called the Instant Centre Pathway which exactly defines the moving path of the centre of knee rotation at any given instant. Uni-axial and geared polycentric hinges do not have this construction; they do not move in this manner and within a brace construct they cannot accommodate or track the complex motion of the knee pro-y.

Another type of hinge design used in orthopaedic splints and braces employed at the knee has two hinge arms each having its own pivot but in this design there are no gear teeth.

trr, in Itris typq tC Mn mamcnEs zrr na brtgod 3nd ceh 3nn an rlys move independently without affecting the other. This type of hinge @s generalty referred to by those ski@@ed in the art as the true @@-axial, true bi-pivotal type. It continues to grow in popularity with the realisabon that such a construction @s supenor to the others @@ providing the freedom necessary to accommodate the complex and changing locus of the axis of the knee throughout the ent@re flex@on@extension cycle.

eotn bipvobt trbcs +nd gaorsd po(ycetne hinect ur, in mechoaPcPd tcmrC thrre linkages. However, the geared integration of the hinge arms in the geared polycent@c type arms causes the loss of one degree of freedom. When used in most ortho@a@dic braces both types require at least one stop at or near the fully extended position to prevent over-travel of the knee into hyperextension. In bracing and general orthopa@d@c and orthotic app@cations a three bar linkage hinge mechan@@m, with all degrees of freedom ava@@able, offers the most practicat and appropnate mechan@cal arrangement for accommo@ating the complex motion oftns )mcc, Tnt PWbC rrthor has bscn aneerr#d fot nwny years with restrrdr mrd dcvsopr of bi pvobl hirrgcs hacwl upon ONa plan95 tausm 24mm nd 40mm.Whm aren ingrs M ursd g POR od bme anmet. tte nza rwrrwrdr travel of tht insts eern polhry of the knee axis which can be accommodated approx@mates to that which is likely to be encountered in the great majority of patients. This was confirmed at Sheffield and Brunel Unversities in the UK in 1988 and 1987.

In Irian d w oonfirmeb, w 19 by mcarrs of crr#d ndco. conrpmr nd faoapbs ga@@ analys@s, that when used at the knee, bi-pivotal hinges with such pivot sp@cings introduce less disturbance to the normal gait (or walk@ng pa@@@@), than either gea@ed polycentr@c two- prvot hinges or uni-axial hinges. Furthermore, it has been shown that piston@ng and z@g- zagging does not occur in such hinges (prov@ded they are fitted prope@ly) when the knee @s under load. This work was camied out at Derby Royal Inf@rmary, Derby, U.K. in 1984 and was presented at the @th World Orthopaedic Congress in Washington DC, U.S.A. 4th-10th May 1987 by Dr. Dav@d Pratt. Dr.Pratts pnncipal co-author was Dav@d Rowtey MD, FRCS now Professor of Orthop@@dics and Trauma Surg@@y. The Univers@ty, Dundee, Scotland.

By way of contrast, if geared polycantric hinges are restrained at a point along each hinge arm some distance from each pivot and flexed they are @nven forwar@s in the oppos@te direct@on to natural knee mot@on. In a brace construct this is exactly the form of restra@@t app@ed, usually by sets of securing straps above and below the knee. This movement is easy to demonstrate in a brace not in place on a leg. However, in a brace construct movement is substan@ally prevented by the securing straps and the net effect is to generate forces which act counter to the flexing forces generated by the flexor muscle groups act@ng on the knee. The opposite effect is encountered dunng extension of the knee in such a brace construct and in both cases, the resolution of these extraneous forces is through a cwnDlwnsd kwpl It is possible, by altenng the architecture of a geare@ polycentric hinge, to partially allev@ate these effects. This can be done by, for instance, introducing a substantial antenor displacement of the femoral hinge arm and a substantial postenor displacement of the tibial hinge arm and arranging the geanng accor@@ngly.Such an arrangement is taug@t in US 4 697 583 to Mason et al, ass@gned to Messrs Don Joy Orthopedic Inc. of Cartsbad, Cal@form@a, USA Another concem to those who have to set up and adjust braces is the total number of parts to be handted when a brace needs adjustment. This is a particular probiem with braces which have incremental extension and flex@on stop. In every commerciatly available system known to the present author which employs @@remental stops, extension stops and flexion stops are secured separately by at least one screw for each stop and there is often a hinge cover which has to be removed as well.

In recent years a great deal of attention has been pa@d by those skilled in the art to the des@gn of functional knee braces which are intended to provide stab@lity for unstable knees. Current opm@on favours des@gna in which hinges are disposed in close approximation to the knee.

have min@mal thickness profiles and generally offer lim@ted control of extension and flexion.

Accordingly, continuously vanable stop mechanisms are now mainly found in reha@@@@tation braces which are used immed@ately following injury or repa@r to knee @@gaments and are otherw@se generally s@mpler braces. In those pat@ents at a later stage of reha@@@@tation and returring to active sport. discontinuous or incremental stop mechan@sms are acceptable in the funct@onal knee braces typ@cally pres@nbed at that stage.

In a functional knee brace intended for use by a person retu@@@ng to active contact sport following a ligament injury, there is an expectation, not always justified, that the brace will provide physical prot@chon for the knee. If wide prvotal sp@cing is employed on the lateral hinge, the medial collateral ligament w@ll recerve @@tt@e, if any, protection from the brace if a substantial, medially directed, lateral blow is suffered when the knee is mod@rately flexed.

Us 4 520 802 to Mercer and Aaserude teaches another bi-pivotal cast bracing hinge featunng wide pivot specing.

SUMMARY OF THE INVENTION The present invention provides a true bi-pivotal hinge, for orthopaedic and orthotic braces used on the human body and particularly at the knee, which has an improved m@remental motion lim@ting mecha@@sm.

In the invention, a true bi-pivotal hinge is provided with a senes of novel, more or less diamond shaped, interchangeable, metal, combined extension and flexion insert stops. Each insert stop body provides at least one and optionally two different angu@ar settings for extension limitation and at least one and optionally, two different angu@ar settings for flexion limitation. In this novel arrangement it is not necessary to have any part of the insert stop accommodated and disposed between the extreme ends of the hinge arms between the prvots.

The arrangement of the invention allows the instant hinge to have narrow prvot spacing in the range 24mm to 30mm which isthe optimal arrangement for a true bi-pivotal hinge. This is because the modified, crossed, four bar linkage mechanism of the human knee has an instant centre pathway which tracks posteriorly as the knee travels from full extension to full flexion by a s@@itar distance.Such an unconstra@ned bi-pivotal hinge, which is a three bar linkage, offers excellent pract@cal accommodation, dunng flexion and extension motron, of the complex motion of the knee's four bar linkage mechan@sm. This is accomp@ished without the introduction of of extran@ous fortes associated with the use of uni-axial and geared polycentnc hinges.

In this invention, there is no requrement for a structure within or formed by the hinge body to lock the stop in place after it has been secured in place. Each dtamond shaped insert stop is secured by a s@ngle screw which passes through either the front plate or back plate of the hinge.This feature, togSher with the optional plurality of different extension stop angle and optional plurality of different flexion stop angles provided on each insert stop allows quicker, easier and more economical adjustment of angular hinge arm travel than is achievable with prior art extension and flexion stops mechanisms for bi-pivotal hinges.

The ease of use of the instant invention is further enhanced by the geometric structure which allows a pair of extension stop fates not in use to be employed as a tab or handle for introducing that pair which is required into the hinge body. The insert stop body may also be held in the conect position by this means whilst the securing screw is placed and driven home.

According to the invention there is provided a true bi-pivotal hinge, with narrow pivot spacing.

for use in orthop@edic and orthotic braces which has a series of single, flat, interchangeable, incremental insert stops made in suitable metals such as titan turn or stainless steel and whid are second in the ecoon angle of the hinge.

According to a first aspect of the invention, the incremental metal insert stops have a fist pair of angled extension stop faoes, one for each independently pivoted hinge arm, each face being disposed at halt the total extension stop angle required.

According to a second aspect of the invention, the incremental metal insert stops have a second pair of angled extension stop foes, one for each independently pivoted hinge arm.

each ftce being disposed at half a total extension stop angle required and optionally differing from the first extension stop angle by a clinically useful increment According to a third aspect of the invention, the incremental metal insert stops have a first pair of angled flexion stop faces, one for each independently pivoted hinge arm, each face king disposed at halt the total flexion stop angle tequirrd.

Acceding to a fourth aspect of the invention, the incremental metal insert stops have a second pair of angled Son stop faces, one for each independently pivoted hinge ann. each fcce king disposed at half a total flexion stop angle required and optionally differing from the first extension stop angle by a clinically useful incremment.

According to a filth aspect of the invention, each interchangeable metal insert stop body is secured by a single screw which passes non-threadedly through either a front plate or back plate of the hinge body and which is received threadedly into the stop body.

According to a sbdh aspect of the invention. the end portion of each approximately diarnond shaped insert stop having the pair of angled extension slop faces not selected may be used as a handle or grip for introaLicing the selected pair of angled extension stop faces into the hinge body at the time of fitting or removal.

According to a seventh aspect of the present invention, each insert stop body is provlded with markings which clearly indicate the lotal angubr values of each pair of flexion and extension stops.

OBJECTS OF THE INVENTION It is, therefore, the principal object of this invention to provide a true bi-pivotal hinge for use in orthopaedic and orthotic braces having narrow pivot spacings, preferably disposed apart by a distance measurement between centres in the range 24mm to 3Omm and prided with a series of interchangeable, fiat, metal, more or less diamond shaped insert stops each offering a plurality of paired extension stops and a plurality of paired flexion stops for limiting extension and flexion travel of both the hinge arms.

It is another important object of this invention to provide a series of insert slops each offering first and second pans of angled extension stop faces, each angled face within each pair being intended to co-operate with one independently pivoted hinge arm and also being disposed at half a total extension stop angle required.Additionally, the total extension stop angle presented by the first pair of extension stop faces optionally differs from that presented by the second pair or extension stop faces by a clinically useful angular increr-iL It is another important object of this invention to provide a series of insert stops each offering first and second pairs of angled flexion stop faces, each angled face within each pair being intended to co-operate with one independently pivoted hinge arm and also Inning disposed at half a total flexion stop angle required. Additionally, the total flexion stop angle preeented by tne first pair of flexion stop faces optionally differs from that presented by the second pair of flexion stop faces by a clinically useful angular increment BRIEF DESCRIPTION OF THE DRAWINGS Other objects and advantages will become clear will become clear as the present invention is described in greater detail, by way of example only, with reference to the accompanying drawings.

In general, a convention of describing the position of structural elements in drawings in relaion to their anatomical disposition has been adopted using terms such as anterior and posterior to desaibe fore and rear with respect to a human body upon which the device of the instant invention would be applied.

In the drawings. RG. 1 is a lateral front view of part of an orthopaedic knee brace fitted with a fiully assembled @@e @@@@@@@@@ @@@ge a@@@@@ng @@ @@@ p@es@@@ @@@@@@@@@ FIG. 2 is a lateral front view of part of an orthopaedic knee brace fitted with a true bi-pivotal hinge with the hinge cover and front plate partly cut away to show part of a first combined extension and flexion insert stop according to the present invention. The hinge arms are shown extended against the stop.

FIG. 3 is lateral front view of the instant hinge with the hinge cover and front plate removed to show a second view of a first combined extension and flexion insert stop with the hinge arms flexed against the stop.

FIG. 4 is lateral front view analogous to Fig 3 showing a first view of a second combined extension and fl-on insert stop according to the present invention. The hinge arms are shown extended against the insert stop.

FiG 5 is a lateral front view analogous to Fig 2 but with slightly different parts of the hinge cover and Innnt plate wt away and a showing a second view of part of a second combined on and flexion insert stop according to the present invention. The hinge aims are shown flexed against the insert stop.

FIGS 6, 7 and 8 are front or lateral views of further combined extension and flexion insert stop configurations according to the present invention.

FIG. 9 is a posterior view of a hinge according to the present invention with a combined extension and flexion insert stop in place.

DESCRIPTION OF THE INVENTION With general reference to FIGS 1 - 9, a true bi-pivotal hinge according to a preferred embodiment of the present invention, has the general designation 10 and is generally represented as peR of an orthopaedic knee brace 12. It is to be understood that hinge 10 will generally but not always, be used in a paired configuration with one such structure being disposed medially and the other laterally with aspect to the human knee.Hinge 10 comprises the major structural elements first and second sustantially flat hinge arms 14 and IS, a substantially Ilat front plate IS and a substantially flat back plate 20. These elements are conveniently made in metals such as aluminium or titanium. As described, hinge 10 is not a handed structure.

Front plate 18 and back plate 20 are disposed in a parallel relationship and hinge arms 14 and IS are disposed between them, each being independently pivotally mounted upon pivot rivet axis means 22 and 24 (shown in section in Figs 2 - 5) provided with bushing means 2@ and2S (28 is shown in section in Figs 2 - 5; 26 is sswn in section in Figs 3 3 and4). The spacing between the centres of 22 and 24 is strongly preferred to be in the range 24mm 30mm.

In the embodiment illustrated, hinge arms 14 and 16 are overmoulded in a suitable soft but durable material such as an iiijeclion moulding grade of synthetic rubber indicated at 30 and 32. Additionally, hinge 10 has a front cover 34, conveniently made in moulded plastics. The first purpose of ove@moulds 30 and 32 and hinge cover 34 is to ensure that metal parts do not impinge upon the person of the wearer and also if the device were to be used in arntact spores to protect Mother participant. A second purpose is to enhance tne cosmetic appearance.Hinge cover 34 has a further purpose which win be described, in context, below.

Each of hinge arms 14 and 16 has an extension 3. and 3. 'which extends beyond and between pivot rivets 22 and 24, respectively but which neither interdigitates with nor touches the other.Posterior edges 40 and 42 of extensions 36 and 38 and the non-ove@moulded posterior edges 44 and 4@ of hinge arms 14 and 16 which tie disposed between front plate IS and back plate 20, constitute abutment faces. Abutment faces 40 and 44 lie in the same plane and when hinge arm 14 is in full extension these faces are also parallel to a line c - c1 joining the centres of pivot rivets axis means 22 and 24. Similar@y faces 42 and 46 are also in the same plane and are additionally obplanar with 40 and 44. When hinge arms 14 and 16 are in full extension, faces 42 and 4@ are also parallel to cadre line c - C1 between pivot rivet axis means 22 and 24.

Abutment faces 40, 42, 44 and 46 co-operate with corresponding structures, described below, provided by each and every one of a series of approximately diamond shaped combined extension and flexion insert stops. Five insert stops in such a series are illustrated and are designated 100, 200, 300, 400 and 500. However, it is to be understood that whilst some of these insert stops are typical of those which may commonly be used, they reprsent only a few of the possible combinations which may be made or required in a rational clinical range from full extension or 0 to about 130 flexion.

Combined extension and flexion insert stop 00 has a structure which is typical of the series.

n is ptanar and made of suitable metals, such as titanium or stainless steel and has a thickness substantially the same as hinge arms 14 and 16. insert stop 100 has a stop body 102 provided with a threaded hole 104. Threaded hole 104 provides means by which insert stop 100 is secured, threadedly, by screw U (shown in section in FIGS 3 - 5) to and against front plate IS and hinge cover 34. Front plate IS has a hole 50 (seen only in FIG 5) for rece@val, non-threadedly, of sam 48 with minimal clearance.Hinge cover 34 has a tapered recess 52, centrally positioned in which is a hole (not seen) also fot receival, non-threadedly, of screw 48. When saew 48 is driven fully home, its head 54, lies just under flush with the surface 56 of hinge cover 34.

AS may be seen by reference to FIGS 3,4 and 5, the centre of hole 50 in front plate IS is located on a line n - n@ normal to and running posteriorly from centre line c - c1. This line also bisects the dislance between the cerrees of pivots 22 and 24. The potion of hie 50 is selected to optimise the geometrical solutions applied to the selection of insert stops.

As may be seen by brief reference to FIGS 6 - 8, insert stops are symmetrical about an axis a - a1 which runs from the apex of the first total extension stop angle to the apex of the second total stop angle. Insert stops are not necessarily symmetrical about an axial line b b@ drawn between the apices of angles between adjacent flexion stop faces. However, the position of the centre of the threaded securing hole illustrated at 104, 2", 304, 404 and 504 in the drawings always lies at the intersection of lines a - a1 and b - b1.

Insert stop geommetry will be strongly influenced by the required stop angles selection but other factors, such as the width of hinge arms 14 and 16, the shape and position of extensions U and 28 and the overall shape and size of binge body 10 and its other major components, are important.

For clarity tines a - a1and b - b1 will be referred to in the general text, hereinafter, as vertical apical axis' and horizontal axis'. respectively In insert stop 100 each member 105, 108 of a first pair of extension stop faces is symmetrically disposed either side of a vertical apical ards at an angle of 5 to and above a horizontal axis, thus presenting, as illustrated in FIG 2, a total extension stop angle of 10 to abutment faces 40 and 42 of extensions 36 and 38 of hinge arms 14 and 16, respectively.

Each member 110, 112 of a second pair of eelenlln stop feces is also symmetrically disposed usher side of the vertical apical axis at an angle of 10 to and below the horizontal axis, thus providing, when required, a second total extension stop angle of 20- for abutment faces 40 and 42.

As seen best in FIG 1 at enlanged scale, tbat part 114 of stop body 102 'which is adjacent to stop faces 110, 112 also functions as a tab or handle. This teature is useful when changing entire insert stops w switching stop values, For instance, in order to use the second pair of extension stop feces 110,112 and provide hinge 10 with 200 of extension block, screw 45 is removed and stop 100 is readily withdrawn using handle 114.Inset stop 100 is tnen reversed and hand@e 118, which is the equivalent part of stop body 102 adjacent to stop faces 106, 108 (seen in FIGS 2 and 3) is used to introduce extension stop faces 110,112 into the correct position within hinge 10. Handle 116 may also be used to hold insert stop 100 in position while saew 48 is re-located and driven home. Provided hinge arms 14 and 16 are emended and flexed against insert stop 100 before screw 48 is fully tightened. stop 100 will ceere itself and line up properly without the need for seondary adjustment of its position.

In insert stop100 each merbeer 118,120 of a first pair of flexion stop faces is srrv disposed either side of the vertil apical axis at an angle of 65 to and abwe the horizontal axis. This arrangement presents, as illustrated in FIG 3, a total flexion stop angle of 130 to abutment faces 44 and 46. Each member 122, 124 of a second pair of flexion stop faces is also symmetrically disposed either side of the vertical apical axis at an angle of 65 to and below the horizontal axis thus also providing a total flexion stop angle of 130 for abutment faces 44 and 46.

Ra@@ 126, 128, 130 and 132 all have the same dimension, which is somewhat greater than the radius of curved portions 58 and 60 of hinge arms 14 and 16. This arrangement is to ensure clearance between insert stop 100 and hinge arms 14 and 16 at all positions of hinge arm travel between seleded extension stop faces and selected flexion stop faces. These radii are all tangential to a circle centred upon the intersection of axes a - a@ and b - b@ This confers the basic diamond shape upon the central body portion of all insert stops. The radii add concavity to the sides and the stop selection superimposed upon this basic architecture dictates the final shape which vanes considerably within the overall basic diamond pattern.

Thus, single combined extension and flexion insert stop 100, located in the net flexion angle of hinge 10 offers extension blocking at 10 and 20 each with, effectively full flexion, This is a rational and desirable set of combinations for a knee in the later stages of rehabilitation following surgical repair to a ruptured anterior cruciate ligament (ACL). A healthy knee, without a brace fitted, may well flex beyond 130 but with a brace in place, above and below knee structures thereof will generally impinge upon one another at large flexion angles.In any case, insert stops acciding to the present invention may readily be made with any required flexion angle value.

Combined extension and flexion insert stop 200 is analogous to insert stop 100 and has the equivalent structures 202 - 232. It differs only in that extension stop faces 206, 208 are symmetrically disposed either side of the vertical apical axis at an angle of 15 to and above the horizontal axis and presents, as illustrated in FIGS 4 AND 5, a total extension stop angle of 30 to abutment faces 40 and 42 Also extension stop faces 210, 212 are symmetricalty disposed either side of the verical apicla axis at an angle of 20 to and below the honizontal axis providing. when required, a second total extension stop angle of 40 for abutment faces 40 and 42 Both total flexion stop angles are 130 , as in insert stop 100.

Combined extension and flexion insert stops 300, 400 and 500, shown isolated in FIGS 6 - 8, are also analogous to insert stop 100 and have the equivalent structures 302 - 332, 402 - 432 and 502 - 532. These insert stops are inctuded to allow a discussion of the rationale for stop selection and of apparent limits of the diamond pattern architecture related to materials selection.

In FIG 6. insert stop 300 has first and second pairs of extension stop faces 304, 306; 308, 310. Both pairs provide an extension stop angle of 0 , which is full extension. Insert stop 300 also has first and second pairs of flexion stop faces 318, 320, 322, 324 both of which offer a flexion stop angle of 45 for abutment faces 44 and 46.

Insert stop 300 is not truly rational under the present invention, an important advantage of which is to provide multiple combinstions of extension and when required, flexion as well. It is inctuded because it represents a worst-case scenario for the instant insert stops when under load. As seen in FIG 6, insert stop 300 has narrow left and right extremities in the region of flexion stop faces 318, 320 and 322, 324, respectively. A 45 flexion stop sectting is a most unlikely selection in a modern functional bracing based treatment regime for late rehabilitation following ACL or other ligamentous reconstruction and is outside the present authors experience.Furthermore, as discussed in the preamble, braces used earlier in the post-operative phase are usually preferred with continuous control of flexion and extension Nonetheless, it is not wished to limit the invention and it is for this reason that the insert stops are recommended to be made in the preferred metals. With such metals used in thicknesses likely to be preferred for hinge arm construction, tests have shown that insert stops configured as in 300 are adequste to withstand forces likely to be encountered during use.

In FIG 7, insert stop 400 represents a more rational but still rather unusual combination in which the first pair of extension stop faces 406, 408 present a total extension stop angle of 10 and the second pair of extension stop faces 410, 412 present a total extension stop angle of 20 . Both pairs of flexion stop faces 418, 420; 422, 424 present a total flexion stop angle of 60 . This insert stop is mainly included to indicate, by comparison with FIG 6, that the amount of stop material available to support compression loads in flexion increases rap@dly with increasing flexion stop angle. Insert stop 400 in FIG 7 is shown with suitable preferred markings. The convention of marking each portion of a stop with the setting it actually has rather than those of the opposite end, is preferred as less confusing.

In FIG 8, Insert stop 500 represents a rational combination in which the first pair of extension stop faces 506, 508 present a total extension stop angle of 10- and the second pair of extension stop faces 510, 512 present a total extension stop angle of 20 . Both pairs of flexion stop faces 518, 520, 522, 524 present a total flexion stop angle of 90 . This insert stop is also inciuded partly to indicate further, by comparison with FIGS 6 and 7. that the amount of stop material available to support compression loads in flexion increases rapidly with increasing flexion stop angle. FIG 8, shows both pairs of extension stop face angles and one pair of flexion stop fay angles of stop 500 bbeUed.

In all the examples illustrated. with the exception of insert stop 300 in Fig 6. combination stops have two extension blocking angles and one flexion blocking angle. This reflects the fact that in practice dunng later stages of rehabilitation of the knee, there is a greater and more frequent requirement to revise extension blocking rather flexion blocking. Those charged with the care of patients, therefore, will often prefer to have to make less decisrons about flexion (which they will in any case often choose to set at full flexion) and have several combinations of extension stop immediately available which involve minimal stop changes.

An advantage of the present invention is that in such a scenario, which is very likely, a carer would need only two insert stops for each hinge. Each insert stop would have both sets of flexion stops providing 130 of flexion block. One insert stop would =. extension blocking alice and 20 @ as illustrated with respect to stop 100 in FK;S 2 and 3. The other insert stop would offer extension blocking at 300 and 40*. Such an approach reduces handling of insert stops and associated pans and thereby saves time.

Obviously a responsible manufacturer would include with a brace incorporating a hinge or hinges according to the present invention, a sufficient range of inert stops to cover all common clinical cir@umstances and make others available as required.In fact such a basic range, covering most needs would probably be configured as follows: Extension Extension Flexion Flexion First Pair Second Pair First Pair Second Pair Stop 1 0 0 130 90 Stop 2 10 20' 130' 130' Stop 3 30' 400 130 130' Stop Ice 20' r 90 Expressed differently. an orthopaedic bace according to the present invention and provided with such as set of insert stops would allow adjustment to.- Full extension with 90 or 1300 of flexion 10 extension block with 80 or 130 of flexion 20 extension block with 90 or 130 of flexion 30 extension block with 130 of flexion 40 On block with 130 of flexion This range, being 8 combinations from 4 insert stop enities, would cover most if not all requirements from early middle to late rehabilitation in a functional knee brace, even where a surgeon favours a 'sraight4hiough' appr@ach. This mvohres using a functional knee brace U@oughout treatment. escheing the use of a traditional so-called rehabilitation brace during the post-operative period and thereby reducing costs.

In contrast, the incremental stop system disc@osed by the present author in US 5 038 765 and applied in the commercial product MasterbraceTM@ described earlier, uses four insert stops to achieve four variations of edension block with only full flexion being allowed. Worse cases are cited in the prior art In the present invention, hinge cover 34 is secured from behind hinge 10 by a self-tapping screw 62 (shown in section in FIGS 2 and 5). Self tapping screw 62 passes non-threadedly through a clearance hole 64 in back plate 20 and engages self-threadingly with a blind pilot hole 6. in a boss 68 (both shown in hidden detail in Fig 1.This feature makes it unnecessary to remove or in any other way handle hinge cover 34 during an incremental insert stop change. In addition, since only a single screw 48, secures the combination extension and flexion insert stops of the present invention, the maximum number of parts which need to be handled is much less than in prior an systems. For instance, a typical insert stop change on a two sided functional knee brace where extension block is attered will involve handling only two screws and two insert stops @ four paNs in all.There is a good chance no new insert stop entities will be needed, however. even if they are needed, the total number of parts to be handled still only rises to six - 40% )ess handling than that required in the 1985 geared polycentric hinge product cited in the prior art statement Finally, the provision of oombination endension and flexion insen stops which feature the advantage of handles deserves some furth discussion.

In general, prior art incremental insert stops are difficult to introduce, remove and secure and this adds to hand time and skower patient throughput. The stop handles pwvided by the present invention and exemplified by 114 and 116 in insert stop 100 overcome this problem.

It might be angued that their protrusion beyond the posterior edge of the ninge body is disadvantageous. However, those skilled in the art will recognise that a protrusion which is ma@amally about @mm by an unselected 40 extension stop (the maximum likely to be encountered) into the posterior, flexion angle of the hinge, is most unlikely to be troublesome.

Any such insert stop is likely to have a 30 flexion stop as its selected functional partner. No patient weanng a functional or other orthopaedic knee brace so configured, wourd or could participate in contact sports.

In contrast. insert stops acoordmg to the present invention, with full extension provided by both first and second pairs of extension stop faces, are likely be used by those who participate incontact sports. However, these insert stops will protrude only about 3mm into the postenor, fiexion angle of the hinge which is an insignificant hazard. Brief reference to FIG 1, which is at eniarged scale, will indicate how little insert stop 100 protrudes, even with the 10 extension block engaged and the 20 extension block functioning as a handle.

In a second embodiment (not illustrated) all the crucial structures of the first embodiment are ideffical except Fat there is no hole 4@ in hinge cover 34. Instead, insert stop6 are secured by an identical sorew passing non-threadedly through a non-threaded hole in back plate 20 which comesponds to hole 50 in front plate 18 of the first and prefemed embodiment. This sorew is received into a tapered recessed hole in an inner hinge cover which comesponds to 52 of hinge cover 34 of the first and preferred embodiment. Such an embodiment might be preferred if it were hit that patients would intedere with the insert stop retaining sorew.

However, such a saew siting would be impossible to access with the brace on the parent and this would detract from some of the advantages of the invention relating to time saving.

Whilst the present invention has been described in respect of particular embodiments, modifications may readily be made by those skilled in the art. It is intended that the claims should cover any such modifications falling within the spirit and scope of the invention.

1 claim:

Claims (13)

1. CLAIMS 1. An orthopaedic and orthotic bi bi-pivotal hinge comprising or a hinge body having a from plate and a back plate disposed in parallel relation and defining a space therebetween; said nlabre and arms being provided with pivotal securing means optimally disposed apart with regard to the physicology of the human knee said independently pivotally mounted hinge arms each being limited in a discontinuous and incremental manner in both extension travel and flexion travel by means of a series of generally diamond shaped planar metal combination insert stops, each of said stops acting on each of said hinge arms and in each of said dncbonL'
2. 2.The hinge of claim 1 wherein, said combination insert stops are provided with first and second pairs of angled stop faces for lim@ting extension at optionally different angles and first and second pairs of angled stop faces for limiting flexion at optionally different angles for limiting extension and flexion travel of both the hinge arms.
3. 3. The hinge of claim 1 wherein, said combination insert stops are each symmetrical about a vertical apical axis and symmetrical or regular about a horoontal Pds having body portions with concave iedleeed sides symmetrically disposed about and tangential to a circle centered on the intersection of said axes.
4. 4. The hinge of claim 2 wherein, first said angled stop face of first said pair for limiting extension travel co-operates with an abut@ent face provided by the posterior edge of an extension between said pivots of first said independently pivoted hinge arm: and second said angled stop face of first said pair for limiting exterision co-operates with an abutment face provided by the posterior edge of an extension between said pivots of second said independently pivoted hinge arm, each of said angled stop faces being disposed at half a first total extension stop angle of said stop.
5. 5. The hinge of claim 2 wherein, first said angled stop face of second said pair for ilmiting extension travel co-operates with an abutment face provided by the posterior edge of first said independently pivoted hinge arm and second said angled stop face of second said pair for limiting extension travel co-operates with an abutment face provided by the posterior edge of second said independently pivoted hinge arm, each of said angled stop faces being disposed at half a second total extension stop angle of said stop and optionally different from said first extension stop angle.
6. @. The hinge of claim 2 wherein, first said angled stop face of first said pair for limiting flexion travel co-operates with an abutment face provided by the posterior edge of first said independently pivoted hinge arm and second said angled stop face of first seid pair for limiting flexion travel co-operates with an abutment face provided by the posterior edge of second said independently pivoted hinge arm each of said angled stop faces being disposed at half a first total flexion stop angle of said stop.
7. 7. The hinge of claim 2 wherein, first said angled stop face of second said pair for limiting flexion co-operates with an abutment face provided by the posterior edge of first said independently pivoted hinge arm and second said angled stop face of second said pair for limiting flexion cooperates with an abutment face provided by the posterior edge of second said independently pvoted hinge arm each of said angled stop faces being disposed at half a second total flexion stop angle of said stop and optionally different from said first fieeion stop angle.
8. 8. The hinge of cairn 1 wherein, said stops are releasably secured by single screw means in the fleelon angle of said hinge, said screw means being received non-threadedly thrwgh either said front plate or said back plate and said screw means being received threadedly into said stops.
9. 9. The hinge of claims 1 and 2 wherein, geometric structure of said hinge arms and said combination insert stops provides for partial accommodation of stop bodies within the hinge body but not between hinge arm ends.
10. 10. The hinge of claims 1 to 8 wherein, said combination insert stops are shaped such that an unselected said stop portion provides a handle or grip structure.
11. II. The hinge of clairns 1 109 wherein, said combination insert stop, are provided with markings to indicate the total angular flies of each of said pairs of extension stops and each of said pairs of flexion stops.
12. 12. An orthopaedic and orthotic bi-pivotal hinge comprising two hinge arms and a hinge body having a front plate and a back plate disposed in substantially parallel relation and defining a space therebetween; said hinge arms being independently pivotally mounted in said space and secured to said plates by pivotal securing means; each said hinge arm being adapted to extend and to flex, the amount of extension and flexion being limited by means of an insert stop acting on each of said hinge arms in each of the directions of extension and flexion.
13. 13. A hinge substantially as hereinbefore described with reference to the accompanying drawings.