Traction appliance permitting mobility

Abstract

The new appliance is for applying a substantially constant degree of traction to an injured body member while permitting comfort movement of the body member per se with respect to the appliance and while permitting bed-free mobility for the wearer thereof. The appliance comprises an elongated rigid skeletal base frame adapted to be placed in comfort alignment longitudinally and externally to a body member having an injured part. Means are provided for maintaining the base frame in that comfort alignment. First and second thrust members are longitudinally spaced from each other in alignment with the base frame; they act upon spaced first and second thrust-receiving body parts located on opposite sides of the injured part of the body member. At least the first thrust member is movable with respect to the base frame. Spring tractive means is provided for maintaining first and second thrust members under as predetermined substantially constant divergent tractive force during longitudinal shifting of the injured body member within the elongated base frame. The spring tractive means is mounted on the appliance for operable connection between the first thrust member and a part fixed to the base frame. It comprises a substantially constant force concentrically coiled metal band.

Description

This invention relates to an appliance for applying a substantially constant degree of traction to an injured body member while permitting comfort movement of the body member per se with respect to the appliance and while permitting bed-free mobility for the wearer of the appliance.

This new appliance is not to be confused with splint appliances such as known heretofore. Splint appliances known heretofore have characteristically immobilized an injured body member, such as one having a broken or fractured bone, by binding it immovably to the splint appliance.

The prior art is replete with a multitude of splint or traction devices which either confine the wearer to a supine or inactive or immobile position or confine the wearer literally to a bed or the like; and the following known prior art patents are illustrative of this: Longfellow U.S. Pat. No. 2,007,127; Siebrandt U.S. Pat. No. 2,052,990; Gray U.S. Pat. No. 2,198,995; Leiter U.S. Pat. No. 2,230,620; Hayden U.S. Pat. No. 2,252,258; Herzmark U.S. Pat. No. 2,282,653; Baker, Jr. U.S. Pat. No. 2,373,371; Maudsley et al. U.S. Pat. No. 2,886,030; Zivi U.S. Pat. No. 3,060,929; Treutelaar U.S. Pat. No. 3,068,859; Treutelaar U.S. Pat. No. 3,085,768; Hare U.S. Pat. No. 3,477,428; Powlan U.S. Pat. No. 3,616,795; Peterssen et al. U.S. Pat. No. 3,661,150; Alessi et al. U.S. Pat. No. 3,683,900.

The device of this invention frees the wearer from bed confinement or a supine position and permits mobility for the wearer. This in turn contributes greatly to the likelihood of high morale on the part of the wearer, and contributes to a relatively rapid return of the wearer to an active role in life.

Several elements in the combination of elements forming the appliance of the present invention have heretofore been known in environments strange to the teachings hereof. For example, substantially constant force springs have been known for a long time; see U.S. Pat. Nos. 2,609,191, and 2,609,192. Despite such knowledge, no one has heretofore provided, insofar as is known, any tractive appliance which permits bed-free mobility for the wearer thereof and also permits comfort movement of the injured body member per se with respect to the tractive appliance while the injured body member is undergoing tractive treatment. The present invention, therefore, constitutes a complete departure from the teachings and understandings heretofore applied and known in the art of placing an injured body member, such as one having a broken or fractured bone, under traction.

The appliance of this invention comprises, first of all, an elongated rigid skeletal base frame adapted to be placed in comfort alignment longitudinally and externally to a body member having an injured part. This base frame, as well as the entire appliance, is free of elements which prevent relative longitudinal movement of the body member within the base frame. Further, the base frame, as well as the entire appliance, is free of elements which require mounting to a stationary structure and thereby prevent movement of the base frame as a unit with the injured body member as the injured body member is moved voluntarily by the wearer of the appliance.

Additionally, the appliance comprises means for maintaining the base frame in the aforenoted comfort alignment on the injured body member.

Next, this appliance comprises first and second thrust members longitudinally spaced from each other for acting upon spaced first and second thrust-receiving body parts located on opposite sides of the injured part of the body member. The first and second thrust members are at spaced locations substantially aligned lengthwise with the elongated base frame of the appliance; and these thrust members are usually but not always within the approximate limits of the length of the base frame. Further, at least the first thrust member is movable with respect to the base frame in a direction substantially aligned lengthwise with the base frame.

Further, the appliance comprises a spring tractive means; and this spring tractive means is for maintaining the first and second thrust members under a predetermined substantially constant divergent tractive force during longitudinal shifting of the injured body member within the elongated base frame, even including any such longitudinal shifting as may involve a change in specific location of a thrust-receiving body part and as may simultaneously involve an alteration of the relative longitudinal spacing distance between the thrust members. Thus the tractive force acting on opposite sides of the injury of the body member is maintained at the predetermined substantially constant condition during longitudinal shifting of the body member within the base frame. The spring tractive means is mounted on the appliance for operable connection between the first thrust member and a part fixed to the elongated base frame, and comprises a substantially constant force concentrically coiled metal band freely rotatable as a unit about the axis of the coiling thereof without substantially building up or lowering the forces stored in the coiling thereof. The band itself is tightly coiled in its natural state and is characterized by exhibiting a substantially constant force toward coiling as any length of the outer end of it is moved from and toward the coil.

Additional advantages and benefits of the invention will be described with the aid of the drawing, made a part hereof, wherein:

FIG. 1 is a schematic perspective view of an appliance according to the invention for treating a broken femur, with a phantom showing of a leg within the appliance;

FIG. 2 is a fragmentary schematic top plan view of a rack holding a parallel grouping of suitable spring tractive means for the practice of the invention;

FIG. 3 is a side plan view taken on line 3--3 of FIG. 2 schematically illustrating details of a spring tractive means for the practice of the invention;

FIG. 4 is a top plan view enlargement of the yoke structure also illustrated in FIG. 1;

FIG. 5 is a schematic side view of an alternate device comparable to the appliance in FIG. 1, but specifically illustrating an adjustment means for changing the degree of tractive force to which an injured body member is subjected;

FIG. 6 is a further schematic showing particularly illustrating an alternate means for applying tractive forces; and

FIG. 7 is a schematic perspective view of a further appliance according to the invention, particularly illustrating telescoping members and particularly also illustrating an operable connection for spring tractive means at a location and arrangement between the first and second thrust members.

Referring to the drawing, particularly FIG. 1, an appliance according to this invention first comprises an elongated rigid skeletal base frame 10. Illustratively, the base frame 10 may comprise two laterally spaced substantially parallel rods 11 and 12. These rods 11 and 12 may be maintained in laterally spaced substantially parallel condition by any suitable bracing elements between the same. The bracing might comprise arched members, such as the arched or looped member 13 at one end of the rods. It also might comprise (where a part of the body of a wearer is not designed to extend, or need not extend, for comfort of the wearer) a rod or brace 14 extending substantially directly from one elongated rod 11 to the other 12. Additionally, further rods may extend in various directions from the base frame where it is desired to provide a cage or some element or member for supporting or protecting a part of the body of a wearer.

The appliance of FIG. 1 is particularly designed for use in the case of a broken or fractured bone such as a femur in the thigh portion 15 of a leg. Thus, a cage-like frame structure for the lower leg part 16 and foot 17 may optionally be added to the basic critical elongated rigid skeletal base frame comprised of the two parallel rods 11 and 12 aforementioned. The lower leg and foot might be within a frame arrangement comprising two parallel rods extending at about a 30.degree. angle from the basic parallel rods 11 and 12 of the base frame, plus connecting rods 20, 21, 22, 23 and brace elements 24 and 25 joining the terminal portion of the angularly extending rods 18 and 19 to one end of the rods 11 and 12 forming the base frame as well as bracing the structure.

Further, support straps 26, suitably of flexible nature, may extend between various parallel rod portions (such as rods 11 and 12 and rods 18 and 19) of the total frame structure; and these strap members 26 contribute to maintaining the base frame structure in a general comfort alignment on the injured body member. The strap elements basically provide resting support for the leg. The loop 13 at one end of the parallel main rods 11 and 12 of the skeletal base frame also constitutes, among other things, a means contributing to the maintaining of the injured thigh in a comfort alignment substantially within the base frame. In effect, the arrangement of both the first and second thrust members, as will be described hereinafter, contribute to maintaining the base frame in such comfort alignment; and depending on the specific arrangement and design for the thrust members, they alone may perform the function of maintaining the base frame in comfort alignment.

To be emphasized is the fact that the base frame is placed in relatively loose comfort alignment about the injured body member. It is longitudinally and externally arranged with respect to the body member to be maintained in traction. No part of the appliance contains any element preventing longitudinal movement of the body member within the base frame; and no part of the appliance requires mounting to a stationary structure. Further, no part of the appliance prevents movement of the base frame, as a unit, with the injured body member as the injured body member is moved voluntarily by the wearer of the appliance. In other words, a person having a broken femur might wear the appliance and walk about on crutches or move about in a wheelchair, depending on the desire of the person and the relative condition of mending and his mental attitude at the stage of mending which his leg has experienced.

The appliance critically includes first 27 and second 13 thrust members longitudinally spaced from each other. The first thrust member 27 suitably may comprise a pin member attached temporarily to a body part, such as through a bone near and below the knee of an individual having a broken femur. This pin member 27 may be threaded and should extend transversely to the longitudinal direction or elongated direction of the skeletal base frame 10, as well as transversely to the length direction of the body member 15 having an injured part. The second thrust member, in the device illustrated in FIG. 1, consists essentially of the loop structure 13 at one end of the substantially parallel rods 11 and 12 of the skeletal base frame 10.

To be observed is that the first 27 and second 13 thrust members act upon spaced first and second thrust-receiving body parts. For example, the area 28 near the knee where the pin member 27 is implanted constitutes the first thrust-receiving body part; and the area at the hip (not shown in the drawing) against which the loop 13 abuts constitutes the second thrust-receiving body part. These body parts are located on opposite sides of the injured femur of the body member 15. Further, the first 27 and second 13 thrust members are at spaced locations substantially aligned lengthwise with the elongated base frame 10 and within the approximate limits of the length of the base frame. At least the first thrust member 27 is movable with respect to the base frame 10 in a direction substantially aligned lengthwise with the base frame. Optionally, however, the second thrust 13 member might also comprise a pin or other means (attached to or implanted on the hip side of a fractured femur) movable with respect to the elongated base frame. For an injured femur, however, the structural arrangement for the thrust members, as illustrated in FIG. 1, is preferred.

The loop 13 comprising the second thrust member suitably may be fixed or attached to the main parallel rods 11 and 12 in a manner permitting adjustment of the angular direction of the loop 13 as well as the relative attitude of it (that is, the location of its connection to one of the main rods 11 and 12 of the base frame as compared to the other main rod thereof). Thus, the second thrust member 13 may be adjusted with respect to the base frame 10, permitting not only a comfort adjustment of it but also permitting the structure of FIG. 1 to be employed with adjusted comfort for either a left or right leg, as needed.

Illustratively, adjustability for loop 13 might be gained by employing a telescoping sleeve-like part 29 and 30 at the ends of main rods 11 and 12, each with a set screw (recessed within body of sleeve parts 29 and 30, as desired) for adjusting and fixing the location of the sleeve parts on rods 11 and 12. A set screw 31 for sleeve part 29 is schematically illustrated in FIG. 1; whereas the set screw for sleeve part 30 is hidden from view in FIG. 1. Further, the ends of loop 13 may be flared or flanged to a slight degree; and this is illustrated for one such end at 32 in FIG. 1. A set screw 33, schematically illustrated in FIG. 1, suitably functions to hold the flared end against the telescoping sleeve 29 at any desired angular orientation for the loop 13. Recessed set screws are preferred; and the interface surfaces between the flared end 32 and the telescoping sleeve 29 (as well as the interface surfaces between comparable parts on the end of main rod 12) are suitably scored or grooved to assist in gaining a friction locking for loop 13 at any desired comfort orientation.

The first 27 and second 13 thrust members are maintained under a predetermined substantially constant divergent tractive force by spring tractive means 34. The spring tractive means maintains the substantially constant divergent tractive force regardless of and during any longitudinal shifting of the injured body member 15 within the elongated base frame 10. Longitudinal shifting of the injured body member may involve a change in the specific location for a thrust-receiving body part; and in the structure of FIG. 1, that is exactly what does happen when the injured body member 15 is longitudinally shifted within the skeletal base frame 10. Specifically, a shifting of the body member 15 within the base frame 10 occurs whenever the individual wearing the appliance of FIG. 1 bends forward at his hips, or pushes the base frame 10 outwardly from his hip area by using his hands. In either event, a change in specific location for a thrust-receiving body part may occur (even to the extent that the thrust effect is transmitted from one's hands to the part of the body actually requiring it, that is, the hip area in the case of a broken femur). Further, such a change may involve, as a possibility, an alteration of the relative longitudinal spacing distance between the first 27 and second 13 thrust members. In the device of FIG. 1, the first thrust member 27 will be moved toward the second thrust member 13 whenever an individual moves or pushes the second thrust member 13 away from his hip area toward thrust member 27. Nevertheless, the tractive force acting on opposite sides of the injury of the body member 15 is substantially maintained at the predetermined substantially constant condition pre-set into the apparatus during such longitudinal shifting of the body member (as well as during lateral and even pivoting shifting of the body member in the base frame).

The spring tractive means 34 itself is mounted on the appliance in any suitable manner to effect an operable connection between the first thrust member 27 and a part or a structure 35 fixed or mounted upon the elongated base frame. Suitably, the structure or part fixed to the elongated base frame may comprise, as illustrated in FIG. 1, a cross bar or shaft member 35. The cross bar or shaft member 35 may carry the coiling of the spring tractive means 34.

If desired, a plurality of tractive means may be mounted on rod 35; and this is specifically illustrated in the fragmentary showing of FIG. 2, where secondary tractive means 36 and 37 are added on opposite sides of the main or primary spring tractive means 34. Such supplemental or secondary tractive means may be engaged or disengaged in operable connection to a first thrust member to vary the strength of traction.

As particularly shown in FIG. 3, spring tractive means 34 comprises a substantially constant force concentrically coiled metal band freely rotatable as a unit about the axis of the coiling thereof. The axis illustrated consists of the center line of rod 35. The coiled metal band is freely rotatable as a unit about the axis of its coiling 38 without substantially building up or lowering the forces stored in the coil 38 per se. This band of metal is characteristically tightly coiled in its natural state and exhibits a substantially constant force toward coiling 38 as any length 39 of the outer end of it is moved from and toward the coiling. The shaft or pin 35 may be rigidly and non-rotatably mounted on a frame part (such as on rods 22 and 23) of the appliance; and a roller bearing (for each spring roll) placed over the shaft. The inner race 40 of the roller bearing may be snugly fixed to the shaft 35, whereas the outer race 41 is freely rotatable under reduced friction conditions because of the rollers 42 included between the inner 40 and outer 41 race. The coil 38 then may be carried by the outer race 41, with the inner end of the band of coiling 38 fixed to the outer race or not fixed thereto, as desired. In any event, the outer race 41 will rotate as the outer end 39 of the metal band is drawn from the coil 38 thereof or returned thereto. (An illustrative alternate arrangement might include a shaft mounted on roller bearings at its ends so that the shaft itself is freely rotatable.)

While a great variety of arrangements may be employed to achieve an operable connection for the spring tractive means between a first thrust member and a part fixed in some way to the elongated base frame, an arrangement such as illustrated in relative detail in FIGS. 1 and 4 offers many advantages. It is simple, but allows for adjustability and contributes to relative freedom from bending action on pin or thrust member 27. Basically the arrangement of elements at the outer end of spring band 39 comprises a yoke arrangement. At the outer end of spring band 39 is fixed, as by a rivet 43, a holding member 44 which may be a triangular bracket in overall shape and which is suitably curved along its outside border portion 45 to encompass or wrap around a cross bar 46. Border 45 locks on cross bar 46 so as to more or less make cross bar 46 a part of the holder 44. Sleeve members 47 and 48 are adjustable in position along cross bar 46 and may be fixed in position by set screws 49 and 50. Extending from sleeves 47 and 48 are substantially parallel arms or flattened rigid strips 51 and 52 of any suitable strong material, suitably metal; and sleeves 53 and 54 are fixed to the ends of strips or arms 51 and 52 opposite the ends thereof attached to base adjustment sleeves 47 and 48. Sleeves 53 and 54 fit over the ends of pin 27 in the thigh 15. As adjustment sleeves are shifted on cross bar 46, the force distribution sleeves 53 and 54 are comparably shifted on pin 27. (Optionally, of course, set screws might be added to fix the position of sleeves 53 and 54 on pin 27.) The band-like or flange-like character of force carrying arms 51 and 52 contribute to stability for the arrangement of elements along lines of force (e.g., from cross bar 46 through sleeve 47, strip 51, sleeve 53, and then to pin 27). Further, sleeves 53 and 54 (plus band-like arms 51 and 52 having a width approaching the length of sleeves 53 and 54) tend to distribute thrust forces along an expanse at the ends of pin 27. The result is that the likelihood of bending pin 27 is reduced. (Pin 27 becomes more difficult to remove from the bone of the leg if it becomes bent.) Thus sleeves 53 and 54 serve the function of reinforcing members on each end of pin 27, imparting a significant resistance to the bending of pin 27. A still further advantage of the arrangement detailed in FIG. 4 is that the two main arms 51 and 52 and their associated elements may be placed in operating position or removed from pin 27 with considerable ease. The yoke structure therefore is conveniently demountable at the time pin 27 is to be removed from the bone. The illustrated structure permits the appliance to be adjusted to fit a variety of individuals.

Still further modifications for the structure illustrated in FIG. 1 are useful. Referring to FIG. 5, the operable connection for a spring tractive means 55 between a first thrust member 56 (comparable to 27 in FIG. 1) and a part or rod 57 fixed to base frame 58 may have a lever member 59 interposed in the line of force. Lever 59 may be fixed to frame 58 for pivoting action at anchor rod or shaft 60. A yoke structure 61 (such as illustrated in FIG. 4) may be connected between pin 56 and a variety of points along the length of lever 59; and this is conveniently accomplished by providing spaced holes along the length of lever 59 and using a bolt and nut or other fastening means to affix bracket part of the yoke (see 44 of FIG. 4) at different points along the length of lever 59. In like manner, the exact connection of the outer end 62 of spring 55 may be adjusted along the length of lever 59. Thus, a variety of strengths or degrees of operative or effective tractive force (of relatively constant performance characteristics) may be realized even though the selected spring means 55 inherently exhibits the same force toward coiling under all conditions.

In comparable manner (see FIG. 6), a lever 63 may be mounted for pivoting at rod 64 intermediate its ends. The end part 65 of spring 66 may be adjustably attached along the length of one arm of the lever 63; and a bracket extension for a yoke structure 67 adjustably attached along the length of the other arm. For the arrangement in FIG. 6, both the spring member 66 and the first thrust member 68 should lie on the same side of the lever.

In FIG. 7, the skeletal base frame is formed of parallel rods 70 and 71 with loop brace connector 72 arched between them. A secondary frame structure is formed of parallel sleeve elements or pipes 73 and 74 (which telescope over rods 70 and 71), plus a connecting brace element or structure between pipes 73 and 74. The connecting brace suitably comprises loop 75 and bar 76 (although one such brace element may perform satisfactorily for bracing the secondary frame in the illustrated structure). Between loops 72 and 75 is affixed the spring tractive means comprising the coil 77 having its outer end 78 fixed to the end of an arm 79 extending from loop 75 toward loop 72. The coil 77 for the spring means is mounted on the outer end of an arm 80 extending from loop 72 toward loop 75. The outer ends of arms 79 and 80 extend in overlapping relationship so far toward the loop to which they are not attached that the forces of traction created by the spring tractive means operably connected between the outer ends of the arms 79 and 80 are effective to cause a divergent tractive force drawing loops 72 and 75 apart. The elements of the structure in FIG. 7 on the side of loop 75 opposite the side toward loop 72 may be omitted. When this is done, the loops 75 and 72 may perform not only all of the essential functions of the first 75 and second 72 thrust members, as aforediscussed, but also the added function of maintaining the base frame in comfort alignment on an injured body part of the wearer. Illustrative applications for such a simplified device include uses as a back brace or neck brace. In either application, the loops 72 and 75 may be contoured and padded for comfort contact on the wearer's body parts at opposite ends of the injury.

Optionally, however, the entire structure outward from loop 75 in the direction away from loop 72 may be incorporated in apparatus useful for maintaining a limb under traction; and under such circumstances, a yoke structure 81 comparable to that illustrated in FIG. 4 may be attached as the first thrust member to the end brace bar 76, thereby rendering loop 75 unnecessary as a first thrust member (and converting its function into a brace element or restraining member or a means contributing to the maintaining of the base frame of parallel rods 70 and 71 in comfort alignment on the injured body member).

Many other variations of specific structural features are possible using the teachings hereof without departing from the essential structural features and functional relationships characterizing the invention. Under all circumstances, however, the wearer of an appliance made according to the teachings hereof is afforded both mobility for himself and a mobility for his injured part within the confines of the appliance, while retaining the required tractive conditions for the healing of that injured part.

Claims

That which is claimed is:

1. An appliance for applying a substantially constant degree of traction to an injured body member while permitting comfort movement of the body member per se with respect to the appliance and while permitting bed-free mobility for the wearer thereof, said appliance comprising (i) an elongated rigid skeletal base frame comprising at least two spaced-apart substantially parallel elongated members adapted to permit said injured body member to be located therebetween and bracing means connected to each of said elongated members for holding said elongated members in said spaced apart relationship, said elongated members being adapted to be placed in comfort alignment longitudinally and externally to a body member having an injured part, said base frame and said entire appliance being free of elements which prevent relative longitudinal movement of said body member within said base frame and free of elements which prevent movement of said base frame as a unit with said injured body member as said injured body member is moved voluntarily by the wearer of said appliance, (ii) means for maintaining said substantially parallel elongated members in said comfort alignment on opposite sides of an injured body member, (iii) first and second thrust members longitudinally spaced from each other for acting upon spaced first and second thrust-receiving body parts located on opposite sides of an injured part of said injured body member, said first and second thrust members being at spaced locations substantially aligned lengthwise with said elongated base frame, at least said first thrust member being movable with respect to said base frame in a direction substantially aligned lengthwise with said base frame, said second thrust member being fixed in position with respect to said base frame, (iv) spring tractive means for maintaining said first and second thrust members under a predetermined substantially constant divergent tractive force during longitudinal shifting of said injured body member within said elongated base frame, even including any such longitudinal shifting as may involve a change in specific location of a thrust-receiving body part and as may simultaneously involve an alteration of the relative longitudinal spacing distance between said thrust members, whereby the divergent tractive force acting on opposite sides of the injury of said body member is maintained at said predetermined substantially constant condition during longitudinal shifting of said body member within said base frame, said spring tractive means being mounted on said appliance for operable linkage between said first thrust member and a mounting part for said spring tractive means fixed substantially intermediate said elongated members of said elongated base frame, said spring tractive means consisting essentially of a substantially constant force concentrically coiled metal band freely rotatable as a unit about the axis of the coil thereof without substantially building up or lowering the forces stored in the coil thereof, said band being tightly coiled in its natural state and being characterized by exhibiting a substantially constant force toward coiling as any length of the outer end of it is moved from and toward said coil, and (v) an operable linkage connecting said first thrust member to said spring tractive means for applying said divergent tractive force.

2. The appliance of claim 1 wherein said second thrust member is secured to said base frame at a location proximate to one end thereof.

3. The appliance of claim 2 additionally comprising means for adjusting the position of said second thrust member with respect to said base frame.

4. The appliance of claim 1 wherein said first thrust member comprises a pin member attached temporarily to said first thrust-receiving body part, with each end of said pin member transversely extending from said first thrust-receiving body part, said operable linkage being connected to each end of said pin member.

5. The appliance of claim 4 additionally comprising sleeve reinforcing means on each end of said pin member for imparting resistance to the bending of said pin member under the forces of said spring tractive means.

6. The appliance of claim 4 wherein said operable linkage of said spring tractive means to each end of said pin member is through an adjustable yoke structure having substantially parallel rigid arms of flat character each lying in substantially the same plane and extending from opposite sides of said pin member to an anchorage assembly attaching said arms to said spring tractive means.

7. The appliance of claim 1 additionally comprising a secondary tractive means for assisting said spring tractive means in maintaining said first and second thrust members under said predetermined substantially constant divergent tractive force.

8. The appliance of claim 1 additionally comprising means for adjustment of the linkage between said first thrust member and said mounting part fixed to said elongated base frame, thereby to adjust the strength of the divergent tractive force between said first and second thrust members.

9. The appliance of claim 1 additionally comprising a supplemental frame member arranged for longitudinal guided movement with respect to said substantially parallel elongated members of said base frame, said first thrust member being carried on said supplemental frame member.

10. The appliance of claim 1 wherein the operable linkage for said spring tractive means between said first thrust member and said mounting part fixed to said elongated base frame lies physically between said first and second thrust members.

11. The appliance of claim 1 wherein said means for maintaining said base frame in said comfort alignment comprises said first and second thrust members.