DEVICE AND METHOD FOR IMPROVING RANGE OF MOTION FOLLOWING SURGICAL KNEE REPAIR

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to provisional patent application 63/678,376 which was filed on Aug. 1, 2024, and is hereby expressly incorporated by reference in its entirety.

FIELD OF THE INVENTION

The invention, also referred to in this document as the apparatus or device, may be inserted on top of the foot pedal of a device commonly known as a recumbent stepper exercise machine. It is shown in this document that recumbent steppers can be used to help facilitate the recovery of patients who have recently undergone total knee arthroplasty (TKA) and are in need of improving range of motion (ROM). In common language, recovering TKA patients need to bend their knees as far as they can. This apparatus will enhance the foot position of a patient on the recumbent stepper to make it easier to use and to increase its benefit as it increases the bend of the knee as the lower leg is directed toward the back of the upper leg.

BACKGROUND OF THE INVENTION

Persons who have undergone surgical total knee arthroplasty (TKA), also known commonly as total knee replacement, and other knee repair procedures, are urged to rehabilitate the repaired joint with the goal of increasing maxROM beyond 125° as recommended by the American Knee Society TKA outcome evaluation score. The minROM goal is typically zero degrees. FIG. 1 illustrates the positioning of a goniometer used to measure knee angles.

While every surgeon has their own guidelines, a typical patient is expected to have a ROM from 1° or 2° minimum, i.e., when the leg is straight, to at least 90° maximum, i.e., when the leg is bent, before release from the hospital after a TKA procedure.

Following release from the surgical facility, patients are typically ambulatory with the help of canes or walkers. The next phase of recovery, including increasing ROM, is typically done under the direction of a physical therapist who directs various strengthening and flexibility exercises. Among these flexibility exercises is the simple procedure known as a heel slide. In this procedure, the patient lies on their back with the surgical knee raised. A slide board is placed under the foot to reduce friction. The patient is requested to bend their knee on their own to the threshold of their pain tolerance. A measurement of the bend angle is taken at this point with a simple protractor like device known as a goniometer. Next, the therapist grasps the ankle and by moving the patient's heel closer to their torso assists the patient in bending the knee further. Again, a measurement with the goniometer is made of this assisted bend angle. These two measurements can be and frequently are shared with the surgeon or his staff.

It should be clear that the therapist is forcing the surgical knee to bend beyond what the patient is capable of on their own. Although painful, the stretching of the various tendons and ligaments that remain around the knee after surgery is of primary importance to the patient's long-term healing, recovery, use of the joint in everyday life, and indeed to their satisfaction with the procedure and life in general.

Physical therapy cannot go on indefinitely for any particular patient with nearly two million TKA procedures annually in the United States. There is a need though to continue to advance the assisted bend angle as described above. Without a therapist to bend the knee using the slide board, a myriad of techniques are demonstrated by doctors and physical therapists in videos on the internet. There is a problem to overcome with these post-therapy techniques. They are subjective relative to providing meaningful pressure on the knee, which is to say, they are neither repeatable nor scalable as the patient attempts to match or exceed the previously achieved bend angles on a per session basis.

These deficits can be overcome by using an exercise device known as a recumbent stepper, also called steppers in this document. There are several companies manufacturing and distributing recumbent steppers. They all feature oversize pedals and arm poles with padded hand grips. With sales in the hundreds of thousands, these machines can be found in most physical therapy facilities and workout facilities worldwide. The model after which the figures herein are patterned is the TRS4000 by NuStep. Other, newer models are similar in design and have pedals that vary only slightly in size and design. These variations in the design of pedals can be accommodated with slight variation to the apparatus itself. It will be understood by those skilled in the art that such variations may be made and equivalents may be substituted for elements thereof without departing from the scope of the disclosure.

In a general sense, a recumbent stepper is designed to be used as a general-purpose exerciser and is especially useful for older patients who might have difficulty with stationary bikes, elliptical exercisers, or stair steppers. These machines have oversize pedals to accommodate regular workout shoes and arm poles for upper body motion. There is a sturdy seat that can be moved to a comfortable distance from the pedals depending on the size of the user. There is a resistance mechanism that can be adjusted for cardio exercise, but this internal resistance is not germane to the ROM applications of this apparatus. There is a display that informs the user regarding steps per minute and other data but again is not relevant here.

The design component of a recumbent stepper that is useful for TKA ROM rehabilitation is that both pedals and both arm poles are mechanically linked. That is to say, if the user pushes one pedal down the other pedal moves up. If the user moves the pedals up and down, the arm poles move the same way, alternating forward and back, whether being grasped and moved via force applied to them or not. More importantly, the reverse is also true. Even if the legs are completely passive, moving the arm poles back and forth will cause the pedals to move up and down in an alternating fashion, thus pushing the heel of the user closer to the torso thus effectively mimicking the heel slide exercise. The amount of bend is modulated both by the position of the seat and the amount of force the patient applies to the arm poles. The closer the seat is to the pedals, the more the knee will bend in accordance with the force applied to the arm poles. Additionally, the user may decide to move the arm poles through their full range or just enough to partially bend the knee at any particular seat position if the maximum bend at that seat position cannot yet be tolerated.

As seen in Table 1 and Table 2 above, by moving the seat ever closer to the pedals during successive exercise sets, the recovering TKA patient can control on their own the process of bending their knee to achieve increasing ROM in a measured and repeatable manner. Thus, the patient can duplicate the action of the heel slide exercise described above by using their arm strength to bend their knee further than they could without an outside agent. This obviates the need for assistance from a physical therapist for the heel slide. Indeed, the use of this invention can continue well beyond the period of the physician prescribed physical therapy even to include self-directed and self-mediated tune-ups undertaken months or years later at any one of thousands of exercise or rehabilitation facilities equipped with steppers and with this apparatus.

Calling attention to the numbers for a 6′ 4″ individual as shown in Table 1 and Table 2 above, where the ROM angles with the apparatus and the ROM angles without the apparatus are nearly equivalent for seat positions very close to the pedals as in seat position one. As described below in, this is caused by a tendency for the heel of the foot to lift off the pedal when this invention is not used.

There is one issue that needs to be discussed in the context of using a recumbent stepper for TKA ROM rehabilitation. This issue concerns the widely released early version of a stepper, the NuStep TRS4000. Other versions or models of steppers may or may not have this problem. Specifically, the display position in the original configuration of the TRS4000 stepper interferes with the free movement of the knees. Still, this stepper is functional for TKA ROM rehabilitation with the original configuration, but care must be taken to guide the knees around the side of the display. It is noted however that the display can be easily raised out of the path of the knees by removing two bolts and, with the display raised, drilling and tapping two new holes. The same bolts can then be placed in the new holes and secured. This adjustment raises the display to a higher position that allows the knees to move freely beneath the display but a still usable position for other exercises.

In the wide range of available recumbent steppers on the market today there may be other models that have some precluding limitations for use as TKA ROM therapy devices. It is not the intent of the author, and perhaps it is not even possible, to survey all models. Suffice it to say, however, that even a cursory examination of models on the web shows that there are dozens of recumbent steppers that can be used to help increase ROM following knee surgeries.

SUMMARY OF THE INVENTION

The invention itself is an apparatus designed to insert into the pedal on the side of a stepper corresponding to the TKA repaired knee. While the apparatus is one unitized piece it naturally has a lower section that fits into the existing pedal. It has a middle section that overlaps the side of the pedal and increases the ankle extension angle of the pedal. This middle section provides the thickness of the apparatus for moving the foot closer to the seat for increased ROM. The upper section provides the same style side rails as a stepper pedal for holding the foot in place. In this manner, it mimics the form and function of the pedal except for these two considerations. Firstly, the foot will be closer to the seat allowing greater knee flexion than without the apparatus at any specific seat setting. Secondly, the angle of the pedal/apparatus combination is increased downward to allow greater plantar flexion (aka extension) of the foot.

Regarding the rails on the apparatus, the design mimics the rails on original stepper pedals with the highest point at the heel of the pedal and then a down slope toward the toe of the pedal where no rail exists at all. This is to allow for users with large shoes that extend beyond the pedal in the front. This same concept is the preferred embodiment of the apparatus as can be discerned in FIG. 1, FIG. 2, FIG. 3, and FIG. 4. Indeed, the rail on the apparatus is higher in the rear than the typical original pedal rail to ensure that the foot of the user does not slip down.

It should be obvious that the adult ankle will not flex to the same angle as the knee. This can be even more pronounced in older individuals with arthritis in their extremities, exactly the kind of person who might need a knee replacement. When the stepper is used without the apparatus for TKA ROM therapy, the heel of the patient's foot tends to rise off the surface of the original petal as greater ROM angles are achieved. This condition can become so extreme that the patient's heel breaches the bottom lip of the pedal and slides down during the exact phase of therapy where bending is most challenging. This will cause constant, difficult, and painful readjustment of the foot on the pedal. The apparatus has a higher rail at the heel than the stepper pedal which helps keep the foot in place. The extra allowance for ankle extension means the heel experiences a lower level of flexion and so will not be as likely to rise off the apparatus as it is off the stepper's standard pedal.

The apparatus is bilaterally symmetrical; thus it can be used with either pedal. In the case of a double TKA, two apparatuses can be used simultaneously.

TKA ROM therapy with the stepper does not involve explosive or vigorous motion, and the design of the stepper supports the legs and body well. Also, the original stepper pedals have raised sides, aka rails, that support the apparatus well. Nevertheless, the apparatus is equipped with straps as depicted in FIG. 5 that are preferably connected with Velcro pads to the apparatus in two places on each side as shown in FIG. 3. The straps can be easily threaded through slots in the existing pedal or wrapped around the pedal, to hold the apparatus securely in place. The preferred element for securing the apparatus to a stepper pedal would be straps fitted with Velcro, however, these straps could be fitted with or substituted by snaps, clips, latches, buckles, laces or any such method suitable for securing the apparatus to the pedals of the various recumbent steppers available. It will be understood by those skilled in the art that such variations may be made and equivalents may be substituted for elements thereof without departing from the scope of the disclosure.

While the disclosure has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements without departing from the scope of the disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teaching of the disclosure without departing from the essential scope thereof. Therefore, it is intended that the disclosure is not limited to the particular embodiment disclosed as the best mode contemplated for carrying out this disclosure but that the disclosure will include all embodiments falling within the scope of the appended claims. Comments including patents and non-patent references cited here and are expressly incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings constitute a part of this specification and include exemplary embodiments of the invention, which may be embodied in various forms. It is to be understood that in some instances various aspects of the invention may be shown exaggerated or enlarged to facilitate an understanding of the invention.

FIG. 1 is a schematic drawing of the invention in position with a user's lower extremity shown in a typical position on the invention in accordance with one embodiment of the invention.

FIG. 2 is a schematic drawing of the invention on one of the recumbent stepper pedals shown from a user's perspective prior to use in accordance with one embodiment of the invention.

FIG. 3 is a schematic drawing of the invention depicting how the invention is positioned above the stepper pedal and inserted downward in accordance with one embodiment of the invention.

FIG. 4 is a schematic drawing of the invention in position on a pedal of the stepper in accordance with one embodiment of the invention.

FIG. 5 is a schematic drawing of an instance of the securing strap with Velcro adhesion points in accordance with one embodiment of the invention;

FIG. 6 are perspective views of the user foot on the stepper pedal without the apparatus depicting the lifting effect on the heel position of the user foot as the seat is moved from a farther position from the pedals (left view) to a closer position to the pedals (right view).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Detailed descriptions of the preferred embodiments are provided herein. It is to be understood, however, that the present invention may be embodied in various other forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but rather as a basis for teaching one skilled in the art to employ the present invention in virtually any appropriately detailed system, structure, or manner.

Regarding materials and construction, it will be understood by those skilled in the art that the preferred materials for the invention would be plastic or resin, but could also be metal, wood, or any other durable material. Also, specific details disclosed herein are not intended to portray a preferred embodiment of the inner construction. Such construction will be understood by those skilled in the art to be solid, hollow, baffled or any other suitable embodiment. Also, the specific details disclosed herein are not intended to imply a preferred method of manufacture. These will be understood by those skilled in the art to be manufacturing methods such as injection molding, 3D printing, milling, even carving or any other suitable method.

Now referring to the figures, FIG. 1 shows a depiction of a user 401 of the apparatus or device 20 positioned on a seat 201 of a recumbent stepper or other appropriate exercise equipment. Arm pole 202 of the recumbent stepper is available to the user. The foot of the user is positioned on apparatus 20 in the preferred embodiment as it would appear on recumbent stepper pedal 203 when the knee is bent at a maximum level based on some particular location of the seat relative to the device. First attachment site 40 and second attachment site 42 are available to secure the device 20 to the pedal with a strap 50.

Still referring to FIG. 1, goniometer 301 is depicted as it would be positioned to take a measurement of the bend angle of the repaired knee of a user. This bend angle is represented by “y”. Note that the goniometer 301 is positioned to measure from the lateral protrusion of the ankle bone on one side to the greater trochanter of the femur on the other. The trochanter in particular is not readily visible and must be located by palpation of the side of the hip. It is especially difficult for the user to take bend angle measurements during a session. However, with the use of a table such as Table 1 above, or with a copy of measurements taken previously by a physical therapist, the user can record and track their progress toward bending goals on a per session basis.

FIG. 2 shows a depiction of the device 20 in the preferred embodiment and the bulk of the recumbent stepper from the point of view of the user 401. In FIG. 2, the device 20 is mounted only on the left pedal 203 opposite the right pedal 203. Armatures 206 support the pedals 203. Arm poles 202 are shown in part. The display support and display 204 are shown in part. The main body 205 of the stepper is also shown in part.

FIG. 3 shows a depiction of how the device 20 in the preferred embodiment fits down into a recumbent stepper pedal 203. The device 20 in the preferred embodiment is rigid. It is unitized with a part that fits into the pedal 203 of a recumbent stepper to provide a better placement of the foot relative to the bend angle of the user's knee. The device 20 comprises a rail 21 around the top of the device 20 which is intended to be longer toward the front and deeper overall than the rail on the original stepper pedal 203. The rail 21 comprises a first side wall 26, a second side wall 28, a back wall 30. Device 20 comprises a bottom 32. The combination of these walls 26, 28 and 30 along with the bottom 32 define a space for a user to place one of their feet. A first end 22 of the device 20 preferably extends further than a first end of the pedal 203. An extension member 60 extends from the bottom 32 of the device 20. This extension member 60 preferably has a greater height z at a second side of the extension member 60 than a height at a first side of the extension member 60. The heights measured are from the bottom 32 to a bottom edge 61 of the extension member 60. This arrangement creates an angle x. In the preferred embodiment, the angle x is preferably fifteen degrees as shown in FIG. 3. In the preferred embodiment, the bottom edge 61 makes contact with the top of the pedal 203, thus supporting the device 20 when used by the user 401.

FIG. 4 shows a three-dimensional view of the device 20 in the preferred embodiment as it appears inserted onto a recumbent stepper pedal 203. A second attachment site 42 is depicted. In the preferred embodiment the second attachment site and the first attachment site is a first type of velcro 46.

FIG. 5 shows the preferred embodiment of a strap 50 preferably made of nylon webbing which could be threaded through slots in the pedal 203 or around the pedal 203 based on the design of the pedal itself as the apparatus is positioned down onto the pedal. In the preferred embodiment, the strap 50 has a first end 52 and a second end 54. The first end 52 and second end 54 are preferably a second type of velcro 48 that is attachable to the first attachment site 40 or the second attachment site 42. The first attachment site 40 is located on a first side 41 of the device, and the second attachment site 42 is located on a second side 43 of the device 20. It will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for design depictions of the strap 50 based on the model and manufacturer of the stepper. When the device 20 is excluded from the pedal 203, the angle y as measured by the goniometer is less than that same angle as shown in FIG. 1, assuming that the seat position is the same.

Referring to FIG. 6, the user's foot on the stepper pedal without the apparatus is depicted showing the lifting effect on the heel position of the user's foot as the seat is moved from a farther position from the pedals (left view) to a closer position to the pedals (right view). The rail 21, specifically the back wall 30, as shown in FIG. 1 help maintain the user's heel in the correct position. The correct position is such that the user's heel is in connection with the bottom 32.