EP0955819B1

EP0955819B1 - Injury preventing ski boots

Info

Publication number: EP0955819B1
Application number: EP96944460A
Authority: EP
Inventors: Javin C. Pierce; Charles K. Adams
Original assignee: Lange International SA
Current assignee: Lange International SA
Priority date: 1995-12-19
Filing date: 1996-12-19
Publication date: 2003-10-15
Anticipated expiration: 2016-12-19
Also published as: DE69630405T2; EP0955819A1; EP0955819A4; JP3449727B2; DE69630405D1; WO1997022271A1

Description

The present invention relates to ski boots comprising a retention and release mechanism providing a safety feature for the prevention and mitigation of the severity of injuries to the anterior cruciate knee ligament. and to provide a safe biomechanically natural rearward articulation.

Various prior art devices have been described relating to improving against injury in the sport of downhill skiing. The vast majority of these disclosures relate to improvements in the ski binding; i.e. that mechanism which is affixed directly to the ski. In addition, there have been some disclosures regarding modification to the ski boot itself but more so from the point of view of providing a mechanism for the wearer to more readily step into and out of the boot. For example, in U.S. Patent 5,136,794 there is reported a ski boot consisting of a lower part and of a shaft, in the form of a collar, which is articulated on the lower part and provided with at least one closing buckle. The shaft comprises, at the rear, a rocker which interacts with a stop which is integral with the lower part in order to lock the shaft in a position inclined forwards. The rocker is held in inactive position upon opening of the uppermost buckle by means of a cable and a spring. Thus, the shaft does not come to be locked at the wrong moment during walking.

Attention is also directed to U.S. Patent No. 5,127,171, and art cited therein, which discloses a ski boot with a shell comprising a shaft in two parts, the rear part of which is connected, on the one hand, to the shell and, on the other hand, to the front part of the shaft by two pair of links. The axis of the articulations on the rear part are situated, in the closed position of the boot, on one side and the other of the plane containing the axes of articulation on the shaft and the front part of the shaft. It is possible to open the shaft wide for putting the boot on, while having only a limited tilting backwards of the rear part. The upper connection can be associated with a closing lever.

In U.S. Patent No. 5,107,608, there is disclosed a ski boot for lessening the incidence of knee injuries which the boot is said to exert a forward directional force on the skier's leg. A releasing means changes the rigid support position for the foot and the lower leg on application of a predetermined level of force by the boot on the wearer. The disclosure in US-5,107,608 goes on to report that rearward pressure of the person's lower leg against the rear leg element of the boot can be sensed by force sensors producing electrical outputs by the use of piezoelectric material. In addition, as illustrated in FIG. 7 therein., a mechanical latch assembly employing a tension spring 96 is disclosed, which is described as urging or maintaining the device in ski position, and when said tension is overcome, a release position is obtained as shown in FIG. 8.

U.S. Patent No. 5,283,964 discloses a boot device for front-to-back immobilization of the upper, which acts on an oscillating level capable of being supported against a stop on the shell base. The device is constituted by a rectilinear-motion control mechanism incorporating an external control device of which an inner part actuates via a cam a sensing device associated with the oscillating lever so as to impart to the latter an angular rotating movement around its pin toward a locked or release position in relation to the stop formed on the shell base.

Attention is also directed to following foreign patent documents: WO 92/05718 and 0514762A2. More specifically, in WO 92/05718 there is disclosed a ski boot for enhancing the safety of skiing. Finally, reference is made to EP-375-604-A. which discloses a ski boot with stop holding the leg forward, and French Patent 2647-649-A which discloses a ski boot with an articulated leg locked in a forward position. which leg is articulated having a clip at the back which pivots around the horizontal axis.

All of the above, however, are distinct from the present invention, in that they collectively fail to provide, in the boot itself, a practical mechanism for mitigation of knee injuries while used in skiing. Accordingly, in the context of the present invention, there is herein provided in the boot a retention and release mechanism which specifically reduces potentially injurious forces to the anterior cruciate knee ligament (ACL). Stated another way, the present invention is designed to provide a ski boot that allows the potentially damaging posterior forces at the spoiler (or upper shaft) section of a ski boot to be absorbed or transduced.

Therefore, it is an object of the invention to provide a ski boot design which restricts the posterior movement of the upper shaft of a ski boot, by allowing posterior travel of the same after a selected level or threshold of force has been obtained.

In addition, the present invention also contains as its objective the development of a unique mechanism to affect cuff displacement and arrest when appropriate to create a more safe environment and enhanced safety to the user.

Moreover, the present invention has as its object the preparation of a retention and release mechanism providing a safety feature in a ski boot design.

Finally, it is a more specific object of the invention to provide a ski bcot design which prevents or mitigates the severity of injuries to the anterior cruciate knee ligament, and to provide a more safe natural biomechanical rearward articulation, in the boot. for the user thereof.

These objects are achieved with the ski boots according to

claims

1 and 2.

The present invention, as will be described in further detail accommodates a range of lower leg angles from about 12 to 15 to about 0 to -3 degrees without causing ankle injury or discomfort. Inherent in the design herein is the feature that the recovery is possible (via stance adjustment with respect to the contralateral leg, combined with the "stop" or limit of rearward movement, supporting the leg) and injury to the ankle is prevented via leg support and reduction of portions of the boot lower that would impinge upon the leg/ankle in rearward motion (plantar flexion). In addition, the moment arm of the ski tail of the present invention is reduced with respect to the skiers' center of gravity thereby reducing forces to the knee while still providing posterior support of the leg and thereby permitting the skier to continue skiing until recovery or falling. In the case of falling, rearward contact with the snow over the ski tail requires less derangement and force loading of the knee joint.

In addition to the above, the present invention provides the ability for the user to adjust and allow for movement into a walking position of about -12 to -15 degrees, by adjustment of the device herein at the boot lower section thereof.

Furthermore, in the predominant backward falling accidental instance when episodes of ACL force is likely to cause a rupture, the flexion of the knee is greater than 90 degrees from full extension (straight), the flexion angle tends to be reduced, by the present invention, when rearward support is again offered by the boot taking advantage of more equitable load sharing of fibers within the ACL. See Anterior Cruciate Ligament Strain In Vivo, Robert J. Johnson et al, Univ. of Vt., Proceedings of the American Academy of Orthopaedic Surgeons, 1989. Specifically, loads are reduced in the anterior medical fiber bundle and redistributed to the posterior lateral fibers of the ACL. as a consequence of release to the approximate 0 degree position.

Coversely, in the less common potential ACL injury episode when the posterior boot support imparts a dangerous force to the knee when the knee is nearly or fully extended (straight), the present invention can permit the knee flexion angle to be increased when rearward support is again offered by the boot again taking advantage of more equitable load sharing of fibers within the ACL. Specifically load concentrations are distributed from the posterior lateral fiber bundle to the anterior medial fibers.

In sum, the present invention comprises a ski boot which provides a mechanical retention and release mechanism providing means for mitigating injury to the anterior cruciate knee ligament when the skier exerts posterior loads, potentially injurious to the knee. to the boot shaft upper, said retention and release mechanism capable of positioning lower leg angles from about +12 to 15 degrees in said retention position, to about 0 to -3 degrees, in a release position.

More specifically, and with reference to FIGURE 5, the present invention comprises a retention and release mechanism comprising a plate 50 which is affixed to a ski boot upper shaft by a pair of fixation tabs to allow hinged fixation, a spring 52 mounted on a single hinge pin under compression to provide sufficient anterior force with respect to the ski boot to induce said upper and lower arm linkages to remain against the posterior element of the ski boot while skiing or to return said armatures to a stable position after release, said spring having insufficient force to prevent the armatures from moving posteriorly to an unstable configuration during release, an upper arm linkage 54 comprising a pair of hinge pin receiving holes for pivotal fixation to said plate 50 and a pair of receiving holes for pivotal fixation to a lower arm linkage 56 comprising a space 58 to permit tool access to adjustment screw 60 and an interference edge 62. The interference edge 62 is in spatial relationship with a coacting interference edge 64 of lower arm linkage 56 such that

linkage elements

56 and 54 revert from a stable (anterior coacting with the boot) to an unstable position (posterior) when a predetermined amount of spring 66 deflection/compression has occurred. The lower arm linkage 56, as noted, contains interference edge 64 and a pair of receiving slots 68 to provide hinged fixation to upper arm linkage 54 and axial translation of 54 with respect to 56. The spring compression cap 59 contains a pair of holes to hold a pair of short hinge pins that connect 54 and 56 and a central axial hole to permit access to spring 66. The release tension adjustment screw 60 contains a capless head to prevent axial loading/interference of spring 66 yet with sufficient keyway interface to permit turning by a tool. The head stays within the spring coils. At 69 is a square threaded compression nut comprising a threaded axially orientated receiving hole for adjustment screw 60 of sufficient width to prevent rotation during tension adjustment, also comprising a visual indicator of spring tension against a scale (not shown). Adjustment screw thrust plate 70 comprises a central indentation strike point for adjustment screw 60 by which inferior spring force is transduced to 56 via tabs comprising a pair of holes for receiving a hinge pin rigidly affixing 70 to 56. At 72 is a cam that supports the release and retention mechanism upon a spring load latch (not shown) whereby the cam can be urged (by means not shown) to pivot anteriorly a sufficient amount to disengage from supporting latch allowing inferior translation of the release and retention mechanism and posterior motion of the boot upper shaft to permit walking, ingress and egress. At 74 is a stirrup mounting bracket which comprises a pair of holes for fixation by screws to a stirrup (lower outer shell cuff element), a pair of holes for receiving a hinge pin and pivotal affixation of 72 and 74 to 70 and 56. Furthermore 74 contains a strike plate coacting with 72 to prevent excessive posterior rotation of 72 providing a stable support configuration until 72 is urged forward to assume a "walk" mode.

FIG. 6 is an assembled illustration of the release and retention mechanism of FIG. 5. Shown again in assembled form are the plate 50, the upper arm linkage 54, interference edge 62, which can also be termed a superior interference contact edge, interference edge 64, which can also be termed an inferior contact edge, lower arm linkage 56, stirrup mounting bracket 74 and cam 72. Also illustrated in FIG. 5 are the adjustment screw thrust plate 70 and square threaded compression nut 69. Finally, FIG. 5 also shows at 74 the stirrup mounting bracket, at 76 the visual tension indicator, at 80 the hinge pin head, at 82 the short hinge pin head, at 84 the head of the single hinge pin, and at 86 the rivet mounting hole of plate 50. Finally, at 88 is illustrated a hinge pin head, and at 90 is shown the flange of 56 that acts to a shoulder to augment the travel limit of spring cap (internal, not shown) against the top of the slot.

FIG. 7 illustrates in further cross-sectional view the release and retention mechanism, in the ski position, more clearly showing the placement of spring 52. The front of the boot is to the left hand side of the release and retention mechanism shown in FIG. 7. FIG. 8 illustrates the release and retention mechanism is release position. Also shown in FIG. 8 at 92 is the contact which occurs as between lower arm linkage and stirrup mounting bracket 74 which further serves to limit travel of the upper arm linkage 54. FIG. 9 illustrates at 94 the cutout section of the boot in the stirrup cuff element for placement of the release and retention device herein, at 96 the stirrup pivot point which rivets to the lower shell of the boot, and finally, at 98, one of the screw hole pairs for mounting the stirrup mounting bracket 74.

FIGS. 10-12 best illustrate in cross-sectional form the release and retention mechanism in both retention and release positions. As illustrated therein, when in ski or retention position, as shown in FIG. 10, the lower arm linkage 56 is urged against the upper shaft 100 of the boot. In addition, shown at 102 is the space or opening as between upper arm linkage 54 and lower arm linkage 56. Also, slot 68 reveals in FIG. 10 that when in the ski position, the short hinge pin head 82 is positioned at the top of the slot 68, due to spring 66 counter force or extension force. In the event of a rearward fall, the skier would lean back on the release and retention mechanism, and load transfer would occur through the mechanism to the bottom of said mechanism, as more particularly illustrated in FIG. 11. As can be seen in FIG. 11, upper arm linkage 54 has been urged downward in slot 68, and pin head 82 is now positioned at the bottom of said slot. In this position, spring 66 has been compressed downward. At this point in time, it can also be seen that space 102 no longer exists, as the edges of the upper arm linkage 54 and lower arm linkage are in contact, as shown at 104. The contact provokes rearrangement into the release position, FIG. 12, by means of forming a fulcrum contact point 104 upon which further compression of spring 66 and the concommitant downward travel of upper arm linkage 54 in slot 68 urges

parts

56 and 54 to rotate away from the upper shaft 100 of the boot, by transferring loads from the stable center of spring 66 to the unstable contact point 104. The rearrangement of the upper and lower arm linkages in this manner allows the upper shaft (boot cuff) to rotate posteriorly until its' travel is arrested by contacting the stationary stirrup (lower boot shaft element) and the folded/rearranged release and retention mechanism housed in the stirrup, this arrest occuring at about 0 degrees forward lean. Cam 72 remains in a stable supporting position during ACL release mode. When the skier is able to rotate the upper shaft element (cuff) forward again the upper and lower arm linkages will rearrange into the stable ski position with the help of spring 52.

FIG. 13 illustrates the ski position, and note therein the stable relationships of the arm linkages and cam 72 on the latch 73. FIG. 14 shows cam 72 being switched by a manual interface (not shown) thereby causing an unstable relationship between cam 72 and the latch 73. FIG. 15 shows both boot upper shaft (cuff element) 106 and boot stirrup (lower shaft/cuff element) 108 rotating posteriorly on their respective axis to permit a normal walking gait or to facilitate egress or gress, as a result of manual switching. FIG. 16 illustrates the relationship of the arm linkages and the boot upper shaft 106 and boot stirrup 108 in the ACL release position. As illustrated therein, the release and retention mechanism when releases provides a substantially vertical position to the skier. Furthermore, and as noted above, when in release position the rearrangement of the upper and lower arm linkages allows the upper shaft cuff element 106 of the boot to rotate posteriorly at which point it is prevented from further travel by contacting the stationary stirrup 108. The contact point is shown in FIG. 16 at 110.

In further summary form, the present invention therefore relates to a latch element for a retention and release mechanism in a ski boot. comprising a cam that coacts with a stop. said cam being positioned in such a manner that posterior forces imparted by a user urges said cam to disengage from said stop at a predetermined level of posterior force.

The present invention can also be described as a ski boot containing a retention and release mechanism providing restriction to posterior movement of the upper shaft of said boot and allowing posterior travel of said shaft after a predetermined level of force has been obtained, comprising a latch which contains a plurality of elements that permits compression and change of length when subjected to rearward force by the upper shaft of said boot. said compression and change of length permitted by compression of an elastic spring element affixed between two mobile elements (14) and (3), said latch pivotally fixed to point (16,17) that is radial to the pivotal fixation point of the overall mechanism to the boot shank characterized in that said latch, under a predetermined amount of force, will compress a spring housing element (14) until a cam (15) affixed to another spring housing element (2) which urges said cam to dislodge the latch from the stop (11).

FIG. 1A, 1B and 1 C represent a front, side, and rear view of the retention and release mechanism of the present invention.

FIG. 2A and 2B represent an alternative embodiment of the present invention known generally as the hinge carriage assembly.

FIG. 3A and 3B further represent the alternative embodiment of the present invention known as the hinge carriage assembly, in greater detail.

FIG. 4A represents the latch of the prior art employed in a ski boot, and FIG 4B represents the latch of the present invention, the side-by-side comparison emphasizing the differences in the latch and cable housing of the present invention.

As can be seen from the foregoing discussion, the present invention relates to a retention and release mechanism formed by a cam that coacts with a stop, said cam being positioned in a manner such that posterior forces imparted to the wearers leg, urges said cam to override or disengage from said stop(s) until the magnitude of force is sufficient to cause the cam to disengage or fully overrun said stop(s) at a predetermined and adjustable level of force.

The invention also relates to a device to a release and retention mechanism having an adjustable element that controls the amount of force required to displace a cam to a degree that it fully overrides its coacting stop(s). This device comprises a spring or an elastic element and a release mechanism such as a cam or ball spring and socket the exact configuration of which can be various and apparent to those skilled in the art of load specific release mechanisms such as ski bindings and the like.

The invention also relates to a release and retention mechanism offering a secondary elastic function providing sufficient resistance to rearward displacement of the boot shaft to enable the wearer to maintain control of the ski. This arrest feature limits the posterior displacement of the boot shaft after the "rear breakout" or release has occurred. An important feature of the present invention is that release or break out is limited. This function can be obtained by the interference of the boot upper with the lower, or by means of a dash pot or stop(s) that coacts with the one or more parts of the primary retention and release mechanism or another portion of the boot upper shaft. The secondary "stop" or arrest mechanism should limit posterior travel of the shaft to less than approximately 20 degrees rearward from vertical.

The invention also relates to a release and retention mechanism that can be configured to offer a staged release that facilitates repeated compression/deflection of an elastic element, and resetting of a latch mechanism into a series of stop elements or likewise by a series of latch elements coacting with the stop.

The invention also relates to a retention and release mechanism offering sufficient rearward displacement of the boot shaft to increase the tendency of the knee joint of the wearer to extend to a degree that reduces the likelihood that injury to the anterior cruciate ligament of the knee will occur.

The invention provides the function of absorbing potentially injurious forces before said forces are sustained by the wearer's knee joint. An elastic element comprising a means of adjusting preload, acts as a means to urge the interface constraining the boot shaft posteriorly to disengage affecting a posterior "release" to the arrest position. The adjustment governs the level of force or load required to affect release.

The invention relates to a ski boot having high rearward upper shaft resistance to flex to provide typical performance found in contemporary ski boots until a rearward force approaching that sufficient to damage the knee is encountered whereby the release and retention mechanism will allow the upper boot shaft to freely rotate rearwards for a small distance sufficient to protect the knee yet enable the skier to maintain control of the ski in a new position until the skier can resume a normal forward skiing posture at which point the retention feature of the invention will engage and support the leg posteriorly until the same potentially injurious posterior force level is again encountered. Alternatively, if the skier cannot recover control after the release episode, the effective moment arm of the ski tail to the knee being shortened increases the likelihood that the skier will fall over the tail of his ski without damaging knee ligaments.

In connection with the above, the present invention describes a ski boot comprising at least one lower foot and heel holding portion with a shaft, in the form of a collar. articulated on the lower part, and comprising connecting means consisting of a latch which interacts with a stop which is integral with the lower part, said connecting means comprising means for fixing or releasing said shaft for rotation relative to the lower part consisting of a cable provided with at least one closing buckle for manually disconnecting said fixation means by pivoting all or a portion of the latch to disengage it from the stop to facilitate upright standing and walking with the boot. including means for automatically disconnecting said latch when an anticipated dangerous level of force is applied to the rear of the shaft by the wearer's leg that comprises an elastic element, a proximal housing which is affixed to the upper shaft, and a distal housing element that is constrained by the proximal housing element in all axis except in compression of the elastic element, a distal element that coacts with the stops that is mobile along the compression axis of the elastic element and is disengaged from said stop when sufficient displacement of the elastic element allows an armature that is pivotally affixed to said to the proximal housing element collide with the stop interface element connected to the distal housing element that via eccentric coaction to its compression axis urges the latch assembly to disengage from the stop.

In addition, the present invention discloses a ski boot having a pivotally mobile upper shaft, and a lower foot and heel holding portion, that comprises a stop and coacting latch sensing mechanism to allow the upper shaft to further articulate in the rearward direction relative to the Lower foot and heel holding portion under the condition of a force applied to said stop and coacting latch mechanism which urges the latch to disengage from said stop. In connection with such embodiment said sensing mechanism preferably comprises a spring and an axially slidable mobile element that coacts with a cam member positioned within said latch that urges a pivotally mobile latch element to cause the latch to disengage from the stop.

In yet still another embodiment, the present invention contemplates the above described retention and release mechanism in a ski boot consisting of a shell surrounding the foot and heel and of a shaft consisting of a front part and of a rear part capable of being tilted towards the rear in order to free the foot and to allow the boot to be put on and off, in which the rear part of the shaft can form a translation movement in addition to a rotation movement, wherein the rear part of the shaft is connected in its lower part to the shell by first means of connection forming axis of articulation with the shell and rear part of the shaft, respectively, which allows a rotation and translation of said rear part in relation to an axis which is defined and fixed in relation to the shell and said upper part of the shaft is connected at another point by a second means of connection, forming an axis of articulation with the front part and rear part of the shaft, respectively, which allows a rotation and translation of said rear part in relation to an axis which is defined and fixed in relation to the front part, the axis of articulation for the means of connection on the rear part of the shaft being situated, in the closed portion of the boot. on one side and the other of the plane containing the axis of the articulation of the means of connection of the shell and the front part of the shaft.

With reference now to FIG. 1A and 1B, the release and retention mechanism is therein illustrated, wherein the following numerals designate the features of the present invention: 1 is the cable, 2 is the cable housing, 3 is a proximal latch element, 4 is a slot in 3, 5 is a pin, 6 is a cable clamping ferrule, 7 is a loop of cable, 8 is a pin holding loop, 9 is a distal articulating contact member, 10 is a pin on articulating stop on boot lower, 11 is an articulating stop on boot lower, 12 is a pin on distal articulating member 13 is receiving notch for dislodging cam element, 14 is distal latch element, 15 is dislodging cam element, 16 is proximal latch element, 17 is similar to 16, but alternative view, 18 is dislodging cam element receiving notch and 19 is similar to 10, but in alternate view.

With reference to FIG. 2A, the cable housing is shown at 20, at 24 is the cable hanger, at 26 is a cam stop, and the cam is shown at 28. FIG 2B shows the hinge pin holes 30. In addition, it should be noted that FIG 2A illustrates the hinge carriage assembly 32 that can be manufactured from a polyacetal material sold under the tradename "DELRIN" by the DuPont Company.

With reference to FIG. 4B shown at 150 is the housing (steel stamping two piece bolt), at 152 the hinge carriage, at 154 the return (spring mount), at 156 the cable and housing, at 158 the hinge to the boot, and at 160 the travel slot.

Finally, it will be appreciated to those skilled in the art, using no more than routine experimentation, that equivalents to the specific embodiments of the present invention can be prepared, and such equivalents are intended to be encompassed by the following claims.

Claims

A ski boot comprising a rigid foot portion having a rigid base and a rigid upper surrounding a foot of a wearer, and a rigid leg element (100) for surrounding essentially a lower portion of a leg of the wearer, and pivot means for connecting said rigid foot portion with said rigid leg element (100),
characterised by a retention and release mechanism comprising at least two mobile elements (3,14; 54,56) one of said elements being linked at one end to said foot portion and the other of said elements being linked at one end to said leg element, and both elements cooperating together at another end through a slot (68) and a pin (82) such that a backward rotation of said leg element on said rigid base results in a relative movement of said pin in said slot against a spring element (66) setting a threshold force, said mobile elements both comprising an interference edge (62, 64, 104) situated on the offside of a straight line passing through said links of said elements to said foot portion or leg element such that when said elements are in contact at said interference edge and said threshold force is reached, said mobile elements are urged to pivot away of said boot thereby allowing a further backward rotation of said leg element around said pivot means. a rigid foot portion having a rigid base and a rigid upper
A ski boot comprising a rigid foot portion having a rigid base and a rigid upper surrounding a foot of a wearer, and a rigid leg element (100) for surrounding essentially a lower portion of a leg of the wearer, and pivot means for connecting said rigid foot portion with said rigid leg element (100),
characterised by a retention and release mechanism comprising at least two mobile elements (3,14; 54,56) one of said elements being linked at one end to said foot portion and the other of said elements being linked at one end to said leg element, and both elements cooperating together at another end through a slot (4) and a pin (5) such that a backward rotation of said leg element on said rigid base results in a relative movement of said pin in said slot against a spring element setting a threshold force, said mobile elements further comprising respectively a dislodging cam element (15) and a receiving notch (13) for said dislodging cam element, such that when after a predetermined relative movement of said pin in said slot, said dislodging cam element and said receiving notch contact each other at a contact point situated on the offside of a straight line passing through said links of said elements to said foot portion or leg element and said threshold force is reached, said mobile elements are urged to pivot away of said boot thereby allowing a further backward rotation of said leg element around said pivot means.
A boot as defined in claim 1 or 2, characterised in that said mobile elements are formed by arm linkages (3,14;54,56).
A boot as defined in one of the preceding claims, characterised in that before said threshold force is reached, said relative movement of said mobile elements is a stable configuration of retention and release mechanism whereby the mechanism remains in a retention position.
A boot as defined in one of the preceding claims, characterised in that when said threshold force is reached, said relative movement of said mobile elements is an unstable configuration of retention and release mechanism whereby the mechanism is urged in a release position.
A boot as defined in one of the preceding claims, characterised in that said threshold force may be adjusted by adjustment means (60,69).
A boot as defined in on of the preceding claims, characterised in that said retention and release mechanism further comprises a second spring (52) inducing said mobile elements to remain against said ski boot.
A boot as defined in one of the preceding claims, characterised in that said link between said mobile elements (3,14; 54,56) and the corresponding foot portion or leg element may be detached in order to disengage one of said mobile elements from the corresponding foot portion or leg element thereby allowing a free rotation of said leg element on said foot portion.