WO2009088303A1

WO2009088303A1 - Joint assembly for manikin or patient simulator

Info

Publication number: WO2009088303A1
Application number: PCT/NO2009/000010
Authority: WO
Inventors: Ian Hoskins
Original assignee: Laerdal Medical AS
Current assignee: Laerdal Medical AS
Priority date: 2008-01-11
Filing date: 2009-01-09
Publication date: 2009-07-16
Anticipated expiration: 2010-07-11
Also published as: NO20080201L

Abstract

A joint assembly (25) is forming a part of an extremity joint (3) connecting a body extremity (2) to a torso (1), or a joint within a limb, in a patient simulator. The joint has a spherical bearing (28), which is biased against a spherical seat (6), which in turn envelops a rigid body extremity tube (4). The tube (4) provides a guide for wires and hoses extending through the joint (3). A retaining means (29; 49) is attached to the tube (4) and holds the bearing (28) against the seat (6). A biasing means (30) is disposed between the retaining means (29; 49) and the bearing (26). The biasing means (30) is made of a compressible elastic material. All parts constituting the joint assembly (25) have a slit (54) to laterally receive wires and hoses extending through the joint (25).

Description

Joint assembly for manikin or patient simulator

The present invention relates to a joint assembly for a resuscitation manikin or patient simulator.

Early resuscitation manikins often consisted of parts resembling the upper part of the body only, especially the torso and the head. To make the manikin more similar to a human body it became more usual to include also the arms and legs. However, these parts played no other role but giving the impression that the manikin had legs and arms. Consequently, the legs and arms usually consisted of flexible materials like foamed plastic and textile.

Over the years these limbs came to include joints like elbow, shoulder, knee and hip, with stiff parts between the joints. Still the limb had no other function but to give the impression of human limbs.

In recent years resuscitation manikins have developed into more and more sophisticated patent simulators. The internal space of the torso has been filled up with valves, hoses, wires, electronic circuits, etc. that serve to give the persons practicing on the patient simulator a close to real life experience. Due to the increased lack of space in the torso, combined with the desire to be able to perform medical activities on the limbs, equipment also had to be put into the limbs of the manikin. This means that wires and hoses had to be fed through the joints of the manikin. At the same time it was necessary to maintain the functionality of the joints, so that the joints gave, as far as possible, the same degree of movement as a human joint.

This has been especially difficult for the hip joint. The thigh has a relatively large internal volume and provides a very good alternative room for large equipment for which there is no more available space left in the torso. Consequently, a relatively large number of wires and hoses will have to pass through the hip joint. At the same time the hip joint has a high degree of mobility, as it can provide movement both outward/inward, forward/backward and rotational. This has imposed a great challenge on the design of the joint. A currently used joint, which is believed to constitute the closest prior art, will now be explained, referring to the following figures:

Figure 1 showing the pelvis and one thigh of a patient simulator in sectional view,

Figure 2 showing a detail of figure 1 including a joint assembly and

Figure 3 showing the joint assembly in isometric view.

Figure 1 shows a pelvis 1 and one thigh 2. The pelvis 1 and the thigh 2 are connected by means of a joint 3, which generally consists of a leg connection pipe 4, a joint assembly 5 and a joint washer 6. The upper part of the thigh 2 rests against the pelvis 1 at a complementary curved interface 7 and is allowed to slide relative to the pelvis 1 in two lateral angular directions and also rotate about an axis coinciding with the longitudinal axis of the pipe 4. To allow for the lateral movement of the pipe 4 the pelvis 1 has a relatively large conical cavity (not shown) facing the thigh 2.

As shown in figures 2 and 3, the joint assembly 5 comprises a spherical bearing 8, which is adapted to bear against the washer 6, which has a complementary spherical surface, so that the pipe 4 is free to move as indicated above. It also comprises a nut 9, which is threaded onto the pipe 4, a nut seat 10 and a flat washer 11. The nut seat 10 receives the nut 9 and the flat washer 11. Between the flat washer 11 and the bearing 8 is inserted a helical spring 12 that biases the bearing 8 against the spherical washer 6.

In this prior art the wires and hoses that are extending from the thigh to the pelvis are fed through the pipe 4 that extends centrally through the joint assembly 5. Since all the wires and hoses are gathered along a central axis through the joint, the thigh is free to move as stated above without imposing excessive movement on the wires and hoses.

However, despite functioning very well when assembled the existing joint has proved to be difficult to assemble. It is also very cumbersome to disconnect the leg from the body temporarily, e.g., for transport or to exchange between different types of legs, like from a healthy leg to a severed limb that simulates a bleeding trauma. This means that the patent simulator has to be carried in one piece. Since the patent simulators contain more and more functionality, they become ever heavier and the newest model exceeds the maximum advised lifting load for one person. This means that the patent simulator has to be carried by two persons and that it will occupy a fairly substantive length during transport.

When assembling the prior art hip joint the pipe 4 is first fixed to the thigh 2, wires and hoses are fed through the pipe 4 and connected to the various equipment in the thigh 2. The wires and hoses are preferably equipped with end connectors at their distal end so that the equipment in the thigh may be easily connected at the appropriate place in the torso upon mounting of the leg. The wires and hoses with end connectors and the pipe 4 are inserted through the above mentioned cavity in the pelvis and through a hole 13 in a base plate 14 of the pelvis of the patent simulator, as well as the spherical washer 6, which is mounted in the hole 13. Then the connectors have to be fed through the joint assembly 5.

The bearing 8 and the nut 9 have an inner diameter which is too small for the connectors to pass through. Consequently, these parts are split, so that the wires and hoses can be inserted sideways into the interior of the part. However, the helical spring, which has a somewhat larger internal diameter than the bearing 8 and nut 9, cannot be split.

Therefore, the end connectors have to be inserted lengthwise through the spring 12. The nut seat 10 and the flat washer 11 could in principle be split, but since they both have approximately the same internal diameter as the spring 12, the splitting of these parts would not solve any problems.

As a result, the end connectors have to be small enough to be able to pass through the inner diameter of the spring 12. Due to the limited diameter, the connectors have to be fed through the spring one by one, starting with the largest connector. When the last connector is passing through the spring a proportion of the cross section has been occupied by the previous wires and hoses fed through the spring, which means that the more wires and hoses that are to pass through the joint, the smaller the final connector to pass through has to be. This also means that the number of wires and hoses that can be fed through the joint assembly 5 is limited. When all the wires and hoses have been fed through the spring, the joint assembly 5 may be threaded onto the pipe end and fixed hereto by screwing the nut 9 onto the end ofthe pipe 4.

If the user wants to remove the legs of the patient simulator to make it easier to carry and transport, he will have to disconnect the wires and hoses and unscrew the nut 9. As the pipe 4 is pulled out of the pelvis, the nut 9, nut seat 10, helical spring 12 and bearing 6 will come free as separate parts. The flat washer 11 is clipped into the nut seat and retained herein. These parts have to be collected and care has to be taken not to lose any of them. When the leg is to be assembled again, the user has to repeat the cumbersome assembly procedure described above and make sure that everything is done in the right order.

The nut 9, nut seat 10, helical spring 12 and bearing 6 will have to be separate parts in order to make it possible to insert the wires and hoses laterally into the nut and bearing while lengthwise into the spring.

The present invention aims to simplify both the initial assembly of this type of joint and the temporary removal of an extremity. The joint assembly may be used in connecting all types of extremities in a manikin or patent simulator, including the head, to the torso. It may also be used to interconnect parts of an extremity, like connecting a calf to a thigh.

This has been achieved by a joint assembly as defined by the subsequent claim 1.

The joint assembly of the present invention will now be described by way of illustrative examples shown in the following accompanying figures:

Figure 4 showing the pelvis and one thigh of a patient simulator, including a joint assembly according to the present invention, in sectional view,

Figure 5 showing the pelvis in isometric view, including the joint assembly of the present invention, Figure 6 showing a detail including the joint assembly according to the present invention, in isometric view,

Figure 7 showing the joint assembly in exploded isometric view,

Figure 8 showing the joint assembly in isometric view and illustrating the compressive function of the nut seat, and

Figure 9 showing an alternative embodiment of the joint assembly of the present invention, in isometric view.

As will be seen by studying the figures, the only difference between figure 1 and figure 4 is the joint assembly 25. Consequently, the following description will concentrate on describing this part and those aspects of the present invention joint assembly which is similar to the design and function of the prior art joint assembly have not been described in detail. Emphasis has instead been put on the features which distinguishes the present invention from the prior art.

The joint assembly of the present invention is best shown in figures 6 and 7. It comprises a spherical bearing 28. This bearing has a greater length than the prior art bearing and extends over the full length of the joint assembly. It also comprises a nut seat 30 and a nut 29, as well as a nut retainer 33. The nut 29 may be identical to the nut 9 of the prior art joint assembly. All parts have a slit to allow lateral insertion of the wires and the hoses.

The joint assembly 25 is assembled by inserting the nut seat 30 into the bearing 28, then inserting the nut 29 into the nut seat and at last inserting the retainer 33 into the bearing

28. The retainer 33 has barbs 34, which are adapted to get caught behind a shoulder 35 near the distal end of the bearing 28; so that the retainer 33 retains the nut 29 and nut seat 30 in place inside the bearing 28.

The nut seat 30 has several functions. It acts as a seat for the nut 29 to position the nut relative to the bearing 25, and it transfers torques imposed on the bearing 28 to the nut

29. It also acts as a biasing element. To achieve the function of positioning the nut 29, the nut seat has a receiving cavity 40 with an inner surface shaped complementary to the outer surface of the nut 29 to prevent the nut 29 from turning relative to the seat 30. It also has a ledge 42 that forms a limit for the inward movement of the nut 29.

To transfer torque from the bearing 28 the nut seat has, as one of its features, a multiple of projections 36 that are received in pockets 37 formed in the interior of the bearing 28. The pockets are separated by walls 50, so that when each of the projections 36 is accommodated in an individual one of the pockets 37, the seat 30 is prevented from rotating relative to the bearing 28.

In addition the nut seat 30 has an outer surface 38 having lobes 51 coinciding with the corners of the nut 29. These lobes have the function of both providing added thickness at the corners of the inner surface, where the material is thinnest and to fit with concave mouldings 52 in a complementary inner surface 39 of the bearing 28. This also contributes to the transfer of rotational movement and torque from the bearing 28 to the nut 29 via the nut seat 30. The bearing 28 has a grooved surface 41 at its distal end to facilitate imposing rotational movement to the bearing 28 by hand.

The nut seat 30 also has features (not shown) that will grip the leg connection pipe and restrict unintentional turning of the joint assembly.

The nut seat 30 is formed of an elastic material. As shown in figure 8 a portion 53 of the nut seat 30 is situated longitudinally between the nut 29 and the bearing 28. This portion will act as a compression spring so that the bearing 28 can be biased to a force of a predetermined magnitude against the spherical washer. Although only this portion 53 need to be compressible, it is preferred to make the whole nut seat of the same material, which it is has been found out should have a hardness of 30 - 90 Shore A, preferably 40 - 80 Shore A. This will give optimal performances both for biasing effect and ability to transfer torques. There are several mouldable materials that have a hardness within these ranges. When assembling the joint, the pipe 4 is inserted to the pelvis 1, as described above in connection with the prior art. The joint assembly 25 is assembled by inserting the nut seat 30, the nut 29 and the retainer 33 into the bearing 28, as described above. Care must be taken to align the slits in the parts so that the joint assembly 26 ends up having a continuous slit 54 along the entire length. Then the wires and hoses are inserted laterally into the joint assembly through the slit 42.

When the joint assembly is screwed onto the pipe it is turned until the elastic projections of the nut seat 30 are compressed to a sufficient degree to bias the bearing 28 with a certain force against the spherical washer 6. The torque that has to be applied to this end is approximately the average torque that can be achieved by hand.

Since the wires and hoses are inserted laterally into all the parts of the joint assembly, the size of the end connectors are limited only by the internal diameter of the spherical washer 6. This diameter is sufficiently large to allow the end connectors used today to pass through. If it is desirable to use larger end connectors, it is also possible to split the spherical washer 6 or make it as two halves that will clip together into the opening 13.

Moreover, it is according to the present invention possible to remove the joint assembly as one piece. This means that the user does not have to keep track of the whereabouts of several parts, of which it is very easy to lose one. It is easy to keep the joint assembly from being lost by simply screwing it onto the pipe 4 after the leg has been removed.

Figure 9 shows an alternative embodiment of the joint assembly. This joint assembly 46 differs from the embodiment of figures 6 and 7 in that the nut 49 has a bayonet fit with the pipe. To this end the nut is equipped with at least one, and preferably two, internal lugs 43 and the pipe end is equipped with a corresponding number of longitudinal slits 44 from the distal end thereof. The slits 44 end in a transverse recess 45, which has a small undercut. When the joint assembly is mated with the pipe 4 the lugs 43 pass into the slits 44 until they reach the recesses 45. A slight turning of the joint assembly will bring the lugs into the recesses 45. The undercut ensures that some force has to be applied to turn the joint assembly in the opposite direction to bring the lugs 43 out of the recesses 45. The length of the slits 44 is carefully adapted to the joint assembly so that when the lugs 43 are turned into the recesses 45, the elastic projections 36 of the nut seat 30 are compressed to a sufficient degree to bias the bearing 28 with a certain force against the spherical washer 6. This embodiment has the advantage that the biasing force can be predetermined very accurately and there is no risk of either achieving a too small biasing force, so that the hip joint becomes loose or over tightening the joint assembly so that the mobility of the joint becomes reduced.

Claims

C l a i m s

1.

Joint assembly forming a part of, a body extremity joint connecting a body extremity to a torso, or a joint within a limb, in a manikin or patient simulator, comprising a spherical bearing, which is to be biased against a spherical seat, the spherical bearing being adapted to envelop a rigid body extremity tube, the rigid tube providing a guide for wires and/or hoses extending through the joint; a retaining means adapted to be fixedly attached to the rigid tube and hold the bearing against the spherical seat; and a biasing means disposed between the retaining means and the spherical bearing, wherein the biasing means is made of a compressible elastic material and all parts constituting the joint assembly have a slit to laterally receive wires and/or hoses extending through the joint when the joint is assembled.

2.

Joint assembly according to claim 1, wherein all the parts of the joint assembly are self- contained in un-mounted state.

3. Joint assembly according to any of the preceding claims, wherein the biasing means is incorporated in a receiving means for the retaining means, the receiving means being adapted to transfer torque to the retaining means.

4. Joint assembly according to any of the preceding claims, wherein the biasing means is made of a material having a hardness of 30-90 Shore A, preferably 40-80 Shore A.

5.

Joint assembly according to any of the preceding claims, wherein the spherical bearing has a part enveloping the biasing means and the retaining means, the spherical bearing being adapted to transfer torque to the retaining means.

6.

Joint assembly according to any of the preceding claims, wherein the retaining means is a threaded nut.

7.

Joint assembly according to any of the preceding claims, wherein the retaining means is a fastening device comprising a bayonet lock.

8. Joint assembly according to any of the preceding claims further comprising a retainer which is adapted to retain the retaining means and the biasing means inside the spherical bearing.

9. Joint assembly according to any of the preceding claims, wherein the biasing means comprises features adapted to interact with the limb pipe to restrict inadvertent rotation of the joint assembly.

10. Joint assembly according to any of the preceding claims, wherein the spherical bearing comprises formations on the outside of its distal end to enhance the grip on the spherical bearing for mounting and de-mounting of the joint assembly.