DK2836184T3 - Dynamic wheelchair seating system suitable for dystonia - Google Patents

Description

DESCRIPTION

FIELD OF THE INVENTION

[0001] The present invention is intended to ameliorate the strains caused by spasms and dystonias (especially those related to extension) in diseased subjects in particular when they are seated onto dynamic seating systems, such as push or motorized wheelchairs.

[0002] Diseases affecting the central nervous system (head-brain traumas, children brain paralysis, evolutionary diseases of the central nervous system, etc.) generally have serious consequences especially affecting the musculoskeletal system. Some of these prevent voluntary control of the muscles of the trunk and lower limbs, and the diseased subjects suffer from acute muscle contractions.

[0003] The present invention relates to a device designed as a dynamic seating system for disabled people or subjects suffering from dystonias, primarily those related to extension. Spasms and contractions from which these patients suffer tend to be particularly fatiguing for the subjects and seriously put the durability of their wheelchairs to the test. The present device is a wheelchair, the supports of which are completely articulated by means of springs and dampeners, so that all the strains do not rest on the patient nor on the wheelchair.

BACKGROUND OF THE INVENTION

[0004] Diseases affecting the central nervous system (head-brain traumas, children brain paralysis, evolutionary disease of the central nervous system, etc.) generally have serious consequences especially affecting the musculoskeletal system. Some of these prevent voluntary control of the muscles of the trunk and lower limbs, and the diseased subjects suffer from acute muscle contractions, which often lead even to the dislocation of greater joints. The specificity and violence of movements make it hard to identify any support for these subjects and force them to remain exiled in a place where, when moving, they do not risk bumping against rigid elements. The medical devices available at present are not suitable for containing a subject, which makes continuous uncontrolled movements. It is worth adding that in order to secure the patient to the device it is necessary to use braces, abduction wedge, etc. The immobility and rigidity of these systems, besides increasing the probability of joint dislocation, also causes a hyper-pressure in the pelvic area with detrimental consequences for the health of the patient.

[0005] The effect of stretched ischiocrural muscles is detected at the level of the pelvis (when presently commercially available seating systems are used), which becomes retroverted with a consequent forward sliding movement thereof, extension of the trunk and posteriorization of the head. In certain cases this event causes opisthotonus (state of serious hypertension and spasticity where the head, neck and backbone of an individual shift into a completely bulged or bridge position) and/or dystonic seizures. Each dystonic seizure tends to distort the posture of the individual on the dynamic seating system and an external intervention is usually required to restore the correct position of the individual on the wheelchair.

[0006] In short time, the reiteration of pushing movements produces structural damages to the wheelchair (head rest, backrest and footrest, which firstly support pushing movements). In short to medium periods there appear even serious lesions of the musculoskeletal system and lesions of the skin (e.g. containment belts may cause excessive pressures with consequent skin redness and tearing), loss of strength in the musculoskeletal system, and loss of joint mobility.

[0007] Although there are pharmacological therapies (such as use of the botulinum toxin and intrathecal infusion therapy with baclofen - ITB intrathecal baclofen therapy - which includes implanting a programmable infusion system, which delivers the anti-spasm drug directly in the point of greater efficacy, or even the use of dopaminergic drugs), rehabilitation is the less invasive approach ensuring better results. It is mainly necessary to seek posture solutions which allow to maintain the seated position with stability, safety and comfort (also during spasms), prevent damages to shoulder blades and to shoulder joints, identify posture elements that let certain districts free for voluntary activities (e.g. the possibility to turn the head to direct one's eyes). The dynamic control of posture allows the user to make temporary posture shifts while continuing to be supported.

[0008] In their study, Cooper at al. show that a dynamic seating system may positively affect the reduction of spasticity and the increase of certain functional activities (Cooper D., Dilabio M., Broughton G., Brown D., "Dynamic seating components for the reduction of spastic activity and enhancement of function", 17th International Seating Symposium 2001). Crane at al. report the reduction in spasticity intensity and in contact pressures, a better posture stability, a better comfort, an improvement in functional aspects, the prevention of damages to the seating systems, and a better vocal and/or breathing ability (Crane B.A., Holm M.B., Hobson D., Cooper R.A., Reed M.R, "A dynamic seating intervention for wheelchair seating discomfort", Am J Phys Med Rehabil. 2007 Dec;86(12):988-93). There have also been highlighted the positive effects of the dynamic posture system in subjects with children brain paralysis when in the seated position and during daily activities (Michael H. and Sheri Simkins, "Effects of Dynamic Wheelchair Seating in Children with Cerebral Palsy", 24th ISS Vancouver 2008 Montana State University (USA) Epicenter Therapy Services, Bozeman, MT).

[0009] A dynamic seating system is that allowing for and supporting a controlled, balanced movement while providing stability to the individual who uses the device. In the practice, a dynamic seating system is a seating system reacting to the forces exerted by the user and somehow allows the extension of the hip joint and/or the adjustment of the backrest. Dynamic seating systems are explicitly designed to resist to and follow the sudden, vigorous and strong movements of the user.

[0010] It has also been observed that a thoroughly designed dynamic seating system induces a decrease in the intensity and duration of the extension pushing movement at the trunk and head level, a lesser hyperextension of the head during spasms, a lesser involvement of lower limbs, a greater consistency of anatomic parts with the components of the posture system during and after the spasm (maintenance of correct posture), a lesser consumption of physical energies by the patient, and an improvement in swallowing and consequent reduction of sialorrhea (Ferrari A. "In tema di postura e di controllo posturale", Giornale Italiano di Medicina Riabilitativa, 2003-l;61-7).

[0011] The object of the present invention is an adjustable modular wheelchair, with points of contact with the patient being all dampened. In particular this wheelchair, as compared to a fixed wheelchair, is provided with the following degrees of freedom: • extension of the footrest (extension along the tibial axis) • rotation of the footrest (flexion and extension of the ankle) • rotation of the leg rest (extension of the knee joint) • rotation of the seat pan (extension of the hip around the transverse axis of the pelvis) • rotation of the backrest (extension of the back around the pelvis) • shift of the headrest (extension of the neck).

[0012] These degrees of freedom, suitably hinged and adequately dampened, allow to support the patient while giving him/her an adequate freedom of movement, when the contractions and involuntary spasms force him/her to extend his/her entire body (or even only parts of it) causing pushing movements against the wheelchair components.

[0013] It is worth noting that a suitably sized wheelchair based on the anthropometric sizes of the patient (as are generally commercially available) brings the rotation joints of the wheelchair close to those of the patient, significantly improving the efficacy of the system. To this purpose, a further adjustment used by the device object of the present invention is that related to the positioning of the containment belts so that no pressure is exerted on the abdomen, but only on the iliac crests (district where no pain is caused to the patient).

[0014] It is also worth noting that, although there exist dynamic seating systems, they only concern certain districts by following an operation principle different from that proposed in this application: they tend to cause the user to push against one of those components (which is kept blocked) in order to rotate those which have been left free. However, this support is a considerably greater burden both for the patient (who in any case finds a painful obstacle to spasms and contractions) and the wheelchair (which continues to have a point on which all the strains and impacts due to the contractions are primarily discharged).

[0015] The implementations of the degrees of freedom used in order to optimize the operation of the wheelchair object of the present invention are briefly described below. For the footrest, leaf springs are used for the flexion and extension of the footrest (i.e., the flexion and extension of the ankle) hinged upon the support tube of the footrest itself; also, the footrest may be pushed in the direction of the tibia (longitudinal axis of the leg): gas springs are used (compression spring and gas dampener integrated in a single cylinder) which are calibrated to control and support the extension along the tibial axis; it is worth noting how it is necessary to use a small mechanism to convert the extension of the mechanical structure to a spring compression, since compression springs may have a greater resistance and it is very difficult to find extension springs capable of bearing loads which are typical of dystonic spasms. The leg may extend freely by rotating around an articulation positioned at the knee level; the return is slightly dampened by the extension tube included. The seat pan is hinged on the front horizontal tube which connects the two half frames of the wheelchair. In turn the seat pan is made integral with the patient by means of belts adjustable in position along the sides of the seat pan itself. Rubber elements dampen the contact between half frames and seat pan. The backrest may rotate about an axis coinciding with the transverse axis of the pelvis. It is capable of tilting while remaining supported by a gas (compression) spring. Finally, the headrest, which is secured to the backrest, may be pushed backwards. In this movement, it is always supported by a gas (compression) spring.

[0016] A device with a dampened seat pan is described in US Patent No. 5,904,398 (Susan Farricielli, 1999).

[0017] A device with a dynamic seating system (limited to the seat pan as such) is described in US Patent No. 6,991,292 (Jon Michael Kasten, Adaptive Engineering Lab Inc, 2006).

[0018] A device with tilting, dampened backrest is described in US Patent No. 2009/0195038 (Mark Carl Underwood, Dickinson Wright Pile, 2009).

[0019] A walking assistance device which transforms from a chair to a rollator is described in US Patent No. 6,619,681 (Charlie Gutierrez, Delano Association for the developmental^ disabled, Delano, 2003); it provides for the assisting device being articulated.

[0020] A device for personal mobility having a partially dynamic seat pan is described in US Patent 2005/00229866 (Wayne Hanson et al., Bozeman, MT, 2005).

[0021] A device which provides a mobile seat pan to follow the movements of the user is described in US patent No. 6,488,332 (Michael Markwald, Interco GmbH, 2002).

[0022] InterCo GmbH manufactures wheelchairs with a dynamic seating system called Aktivline. Pro Medicare has developed a wheelchair with a dynamic seating system called Adacta Klim.

[0023] Miller's Adaptive Technologies (http://www.millersadaptive.eom/1 manufactures components for dynamic seating systems.

[0024] James Patrick Kitchen: "Design of Wheelchair Seating Systems for User with High-

Tone Extensor Thrust", 22 May 2006 shows some other dynamic wheelchair seating systems. SUMMARY OF THE INVENTION

[0025] With respect to the first two patents, the invention introduces considerable differences, since it lets all the push points free. The same applies to US patent 2009/0195038 (which limits the articulation of the backrest only).

[0026] US Patent No. 6,619,681 described a widely articulated but not dampened chair, which is not capable of supporting dystonic thrusts.

[0027] US Patent 2005/00229866 limits the articulation of the seat pan, as the previous ones.

[0028] The products from InterCo tend to cause the patients to lean their feet onto the fixed footrest, and in fact they do not discharge the involved strains completely, but only partially. The same applies to the device called Adacta Klim.

[0029] The components of Miller's Adaptive, which do not cover all the joints, do not form part of a unitary design and thus they only locally alleviate the thrusts.

[0030] The seating systems built so far provide, in order to function, the simultaneous involvement of seat pan and backrest (in some cases also the footrests), which are tightly bound to each other and thus limit the movement of a district to a movement which is induced by another district; thereby, the extension schemes are not followed, involving the single districts in a non-constrained manner. In the currently commercially available wheelchairs, a single district always involves and moves another district, thus preventing the user from pulling or pushing, in terms of quality and quantity of the strain, only the district which at that time is more significantly affected by the spasm; experience teaches that in the same user spasms which appear are never identical to the preceding and following ones, neither in terms of intensity nor duration or affected district; therefore, only a system completely releasing one district from the other may follow all the spasms in their variations, based on localization district, intensity and direction.

[0031] In conclusion, the present invention, as compared to existing solutions, addresses the problem in its entirety, without limiting to a few musculoskeletal districts. This type of approach is completely innovative, in fact it allows any type of strains to be discharged and not delocalized to other districts. The advantages of this dynamic seating systems are apparent: • increase of comfort of the user • improvement of the pelvis stability • increase of tolerance to the seated position • reduction of muscle and joint pain and fatigue of the user • wide limitation of skin injuries • reduction od "bumps" caused by sudden spasms • considerable reduction of damages to the assisting device.

[0032] In effect, the use of dynamic seating systems is quite recent and therefore still needs to be defined.

[0033] The invention is defined by the independent claim. The dependent claims define advantageous embodiments.

[0034] The present invention seeks to address the problem by summarizing the various solutions, introducing new ones (e.g. the rotation of the footrest corresponding to the rotation of the ankle), and using all the components synergistically (all the articulations of the seating system work together simultaneously, each supporting the strain of the musculoskeletal district of interest), and optimizing all the components based on the requirements of the user (for the correct functioning of the device it is worth attempting to have the anatomic rotation axes coinciding with those of the articulated seat pan). With regard to this last aspect, the present invention, in order to obtain the maximum efficacy of the dynamic wheelchair, not only does it use a wheelchair which can be adjusted based on the anthropomorphic sizes of the user, but also shifts the axes of the knee and hip joints (main districts where spasms are located) so that better results are obtained.

[0035] Normal dynamic wheelchairs are mostly suitable for dystonic or spastic subjects only, while they are not suitable for subjects with head trauma as is that of the present invention. Furthermore, in the presently available systems, it is essential to secure the feet of the subject with belts; such a situation should be considered as not being compatible with all types of disease (and, in any case, not comfortable).

[0036] A further advantage is the modular nature of the assisting device: the wheelchair object of the present invention does not establish that all the segments are dynamic, but it is possible to implement only those that are strictly necessary to obviate the discomforts related to a specific disease. For example, those who suffer from head trauma are likely to require the dynamic footrest only and not the other segments or, if they show rigidity of the trunk, the dampened backrest will be required, but not the dynamic seat pan (but rather the positioning device of the pelvic belt).

[0037] In particular embodiments, the articulated wheelchair may be propelled by a motor or motors and endowed with a command device in order to increase the user's independence or endowed with a command device for the assistant so that the assistant can use the device with greater ease.

[0038] In further embodiments, the articulated wheelchair may comprise further dynamic solutions selected from a group comprising: 1. a. a rotating headrest in order to support the head shaking; 2. b. rotating armrests in order to support spasms and rotation of the arms and the trunk; 3. c. a seat pan which can rotate along the sagittal axis in order to support spasms and rotation of the trunk, and 4. d. rotating leg rests in order to support spasms and internal or external rotation of the legs.

BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The present invention will be better understood with reference to the following drawings, which describe the various components of the device.

Fig. 1 shows the device in its complete configuration, in the two configurations of rest and extension.

Fig. 2 shows the detail of the headrest dampening.

Fig. 3 shows the dampening movement of the backrest.

Fig. 4 shows the adjustment of the tilting plane of the seat pan.

Fig. 5 shows the possibility to rotate the seat pan plane in order to follow a situation of spasticity.

Fig. 6 reports the possibility to extend the legs around the knee joint.

Fig. 7 shows the possibility to drive the footrest away from the knee and the dampening system thereof, and

Fig. 8 shows the rotation of the footrest and the return spring thereof.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0040] Fig. 1 shows the proposed device in its complete possibility to articulate. There are to be found the dampening system 1 of the headrest, the rotation 2 of the backrest, the rotation 3 of the seating plane, the rotation 4 of the cushion with respect to the seating plane, the rotation 5 of extension of the knee, the extension 6 of the footrest, and the rotation 7 of the footrest itself.

[0041] Fig. 2 shows the detail of the dampening system 1 of the headrest, in its configuration at rest (top) and in its compressed configuration (bottom). When the head pushes against the cushion 8, rod 9 also slides into the guide 10 integrally fixed to rod 11 and, through the latter, to the frame. Gas springs 12 follow the pushing movement and then restore the rest position. They are secured to the supports 13 integral with the guide 10 (and thus with the frame) and with the sliding rod 9.

[0042] Fig. 3 shows the rotation mechanism 2 of backrest 14. The backrest 14, by being subjected to the pushing movements of the back, rotates about the hinge integral with the frame. Backrest 14 is integral with the lever 16, which, by rotating, then compresses the gas spring 17, the other end of which is secured to the frame. Thereby, the spring 17 still follows the movement and, once the pushing movement from the back is ended, returns the backrest 14 to its rest position.

[0043] Fig. 4 shows the rotation mechanism 3 of the seating plane 18. The seating plane 18 may rotate about the hinge 19 integral with the frame, once the relevant unlock lever 20 is actuated. Such a rotation is dampened by the gas spring 21.

[0044] Fig. 5 shows the rotation 5 of the cushion plane 22 about the tube of the seating plane 23. The cushion plane 22 is caused to rotate by the user's pelvis, which is secured by means of containment belts which engage the sliding supports 24 which are movable along guides 25. The rotation occurs by virtue of hinges 26 and the return is dampened by rubber dampeners 27.

[0045] Fig. 6 shows the rotation 5 of the leg rest system 28 about hinge 29 by means of an articulated parallelogram-shaped system.

[0046] Fig. 7 shows the extension 6 of the footrest 30. When the user's feet push against the footrest 30, tube 31 slides into tube 32, which acts as a frame.

[0047] Tube 31, when sliding, also brings down tube 33, which is connected to the gas spring 34. The other end of the gas spring 34 is connected to the tube 31. When the pushing movement of the feet ends, the gas spring 34 returns the footrest 30 to its rest position.

[0048] Finally, fig. 8 shows the rotation 7 of the footrest 30 under the pushing movement of the feet and ankle of the user. The footrest 30 rotates about the tube 35 by virtue of the hinge 36 and, once the pushing movement of the user ends, the laminated (or leaf) spring 37 returns it to its rest position.

[0049] The system may be equally implemented with two half footrests, even entirely independent when the tube 35 is divided into two independent halves: this would allow for asymmetrical pushing movements of the two lower limbs (different extensions around the knee axis, different pushing movements with a tendency to push the footrest away, different rotations of the ankle and foot).

REFERENCES CITED IN THE DESCRIPTION

This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

Patent documents cited in the description • US590439BA Γ001β1 • US6991292B ί00171 • US2009Q195038A Γ06181 Γ0025] • US6619681B 10019) (0028) • US200500229866A ί00201 IOQ271 • US6488332BΓ0021Ί

Non-patent literature cited in the description • CRANE B.A.HOLM M.B.HOBSON D.COOPER R.A.REED M.P.A dynamic seating intervention for wheelchair seating discomfortAm J Phys Med Rehabil., 2007, vol. 86, 12988-93 100.081 • Effects of Dynamic Wheelchair Seating in Children with Cerebral PalsyMICHAEL H.SHERI SIMKINS24th ISS VancouverMontana State University (USA) Epicenter Therapy Services20080000 (0808) • FERRARI Aln tema di postura e di controllo posturaleGiornale Italiano di Medicina Riabilitativa, 2003, 61-7 Γ00101 • JAMES PATRICK KITCHENDesign of Wheelchair Seating Systems for User with High-Tone Extensor Thrust20060522 [0Ω24]

Claims (4)

PAT E NT K RAV 1. Articulated wheelchair (1, 2, 3, 4, 5, 6, 7) equipped with dynamic hardware solutions to increase seat tolerance, reduce nuisance and pressure on the user and to prevent damage to the chair during the user's muscle spasms, including the articulated wheelchair : a. A module frame suitable for various anthropometric sizes; b. a footrest (30, 34, 35, 36, 37) capable of pivoting between an initial position and a pivotal position to allow for bending and extension of the ankle, with leaf springs (37) moving the footrest back to the initial position, the footrest (30) ) is further designed to slide between a resting position and an extended position so that the user can push the feet downward, the footrest (30) being provided with a gas spring (34) to bring the footrest back to the resting position: c. a legrest (28) , 29,31,32,33), which can rotate to enable the bending and extension of the leg around the knee joint; d. a seat bowl (18, 19, 20, 21, 22, 23, 24, 25, 26, 27) that can rotate to allow extension of the thigh around the knee; e. a backrest (14, 15, 16, 17) capable of rotating, preferably at the hip level, between an initial position and a rotated position to allow the extension of the user's back, the backrest being provided with a gas spring (17) to bring the backrest back to the starting position; f. a head restraint (8, 9, 10, 11, 12, 13) designed to slide between a resting position and a compressed post to support a head during a spasm causing a neck extension and to bring the head returning to its initial position when the spasm ends, the head rest being provided with a gas spring (12) to return the head rest to the rest position; and g. an adjustable seat belt moving along the seat cup (22) to comfortably attach the user's rear to the seat cup itself. An articulated wheelchair according to the preceding claim, wherein the wheelchair is driven by a motor or motors and is equipped with a control device to increase user independence or is equipped with a control device for the helper so that the helper can use the device more easily. An articulated wheelchair according to any one of the preceding claims, with further dynamic solutions selected from a group consisting of: a. A rotating headrest to support the head shake; b. rotating armrests to support spasm and rotation of the arms and body; c. a seat bowl which can rotate along the sagittal axis to support spasms and rotation of the body; and d. rotating leg supports to support spasms and internal or external rotation of the legs. An articulated wheelchair according to the preceding claims with two footrests, one for the left foot and one for the right foot to support asymmetrical spasms.