GB2274994A

GB2274994A - Assessment prosthesis and prosthetic leg

Info

Publication number: GB2274994A
Application number: GB9401779A
Authority: GB
Inventors: Geoffrey William Ives-Brown
Original assignee: REHABILITATION SERVICES Ltd
Current assignee: REHABILITATION SERVICES Ltd
Priority date: 1993-01-30
Filing date: 1994-01-31
Publication date: 1994-08-17
Anticipated expiration: 2014-01-31
Also published as: GB2274994B; GB9401779D0

Abstract

An assessment prosthesis for use with a trans-tibial amputation, comprises an upper shell (40 - 41) flexibly secured to the upper leg, and a lower shell (43) pivotally connected thereto, the lower shell being connected to a rigid shin member (46) which in turn carries a prosthetic foot, and containing an inflatable socket (44, 45) for receiving the stump. The prosthesis allows the patient's knee joint to be exercised. The invention also provides a similar prosthetic leg for longer term use with such an amputation in which the lower shell takes the form of a socket specifically moulded to receive the individual patient's stump. <IMAGE>

Description

ASSESSMENT PROSTHESIS AND PROSTHETIC LEG Field of the Invention This invention relates to an assessment prosthesis for use with a trans-tibial amputation, and to a prosthetic leg for longer term use with such an amputation.

Background to the Invention The fitting of a definitive artificial limb post-operatively is generally deferred to allow post-amputation swelling to settle and the suture line to heal.

However, it is deemed essential to remobilise the person as soon as possible to avoid problems such as pressure sores and thrombosis. The physiotherapist will endeavour to carry out this task using equipment such as walking frames and crutches. After a period of eight to ten days, a Pneumatic Post-Amputation Mobility (PPAM) aid may be fitted to the amputated leg.

Figures 1 to 3 of the drawings illustrate a prior art device of this type. The PPAM aid is a rigid metal frame consisting of two side members 1 terminating at a metal rocker base 2, and carrying between them three rings 3. The frame houses an inflated plastics socket 4 that splints and supports the amputated leg. This system does not allow the use of the patient's own knee joint, and therefore exercise of the residual limb is limited, as illustrated in Figure 3. The PPAM aid cannot be used if the residual limb is flexed at the knee through an angle greater than 150, as can be seen from Figure 2, because the straight frame is unable to accommodate flexion contractures.

The present invention provides an assessment prosthesis which permits full flexing of the knee joint.

A problem with conventional articulated prosthetic legs for longer term use with trans-tibial amputations is the complexity of the pivotal connection between the upper and lower parts of the prosthesis. This leads to relatively high cost of manufacture and assembly. Articulation is required where the prosthesis has to provide additional support for the wearer's knee, for example where tendon damage has occurred. Another aspect of the invention provides a prosthetic leg of this type which is simpler and cheaper to manufacture than conventional prostheses.

Summary of the Invention The present invention provides an assessment prosthesis for use with a trans-tibial amputation, comprising an upper shell flexibly secured to the upper leg, and a lower shell hingedly connected thereto, the lower shell being connected to a rigid shin member which in turn carries a prosthetic foot, and containing an inflatable socket for receiving the stump.

Preferably, the inflatable socket comprises a separately inflatable chamber to provide support for the front of the wearer's knee.

The invention also provides a prosthetic leg for use with a trans-tibial amputation, the leg comprising an upper shell flexibly securable to the upper leg, a lower shell for receiving the wearer's stump, the lower shell being attached to a rigid shin member having a prosthetic foot connected thereto, the upper and lower shells being directly pivotally connected together by means of an aligned pair of pivot pins.

The pivot pins are suitably threaded flanged bushes locked by screws.

The upper and lower shells are suitably moulded from a plastics material, the upper shell having, for example, a flexible polyethylene thigh band supported in a rigid plastics knee cage, for example of polypropylene. Preferably, the lower shell is custom-moulded to conform closely with the wearer's stump.

Brief Description of the Drawings In the drawings: Figures 1 to 3 illustrate a prior art device; Figure 4 is a perspective view of an example of an assessment prosthesis according to the invention, with the inflatable socket removed; Figure 5 is a partial view corresponding to that of Figure 4, but showing the inflatable socket in place; and Figure 6 is a side view of the prosthesis being worn by an amputee.

Detailed Description of the Illustrated Embodiments Referring to Figures 4 to 6, the assessment prosthesis comprises a flexible polyethylene thigh band 40 supported in an upper shell or rigid plastics knee cage 41 that is mounted on pivots 42 fixed to a lower shell 43 that is the residual limb container. The connection between the thigh band 40 and the knee cage 41 is via screws 41a, permitting vertical adjustment between the two parts to accommodate variations in patients' thigh lengths. An inflatable plastics socket 44, having an inflation valve 44a is placed within the container 43 to stabilise and support the residual limb below the knee. The socket has a separately inflatable compartment 45 positioned just below the knee cap for additional support. This has its own inflation valve 45a.

A modular shin 46 and SACH (Solid Ankle Cushioned Heel) foot 47 are mounted on to the base of the residual limb container 43. The modular shin 46 is of the type described and claimed in our co-pending UK Patent Application No 9400305.0, and allows change of length below the knee. The thigh band 40 will slide and lock within the knee cage 41, allowing length changes above the knee to accommodate thigh length variations. The proximal shape of the thigh band is designed to fit the left or right thigh.

The prosthesis can be fitted to the patient five to ten days post-operatively, depending on the general health of the patient. The prosthesis is fitted to a patient by taking two measurements from the patient's sound limb, the crotch to knee centre, to give the thigh length, and the knee centre to floor measurement, to give the shin length. The prosthesis is then set up off the patient to give the required length. The thigh and shin lengths are set according to the measurements from the sound limb, and then the prosthetic foot is selected to suit the patient's footwear.

The deflated socket 44 is placed in the container 43, and the patient's residual limb and thigh are inserted into the thigh band and the inflatable socket. With the patient standing to apply weight to the prosthesis, the thigh support band 40 is tightened, and the inflatable socket 44 is inflated, with the patient's knee positioned between the knee cage 41 and the lower shell or container 43, to a suitable pressure not exceeding 40 mm Hg. The patient is then able to walk using his or her own knee joint, as illustrated in Figure 6.

In the case of an articulated prosthetic leg for the patient's longer term use, a similar structure can be employed, but with the lower shell taking the form of a socket specifically moulded to receive the individual patient's stump.

Claims

1. An assessment prosthesis for use with a trans-tibial amputation, comprising an upper shell flexibly secured to the upper leg, and a lower shell hingedly connected thereto, the lower shell being connected to a rigid shin member which in turn carries a prosthetic foot, and containing an inflatable socket for receiving the stump.

2. An assessment prosthesis according to Claim 1, wherein the inflatable socket comprises a separately inflatable chamber to provide support for the front of the wearer's knee.

3. An assessment prosthesis for use with a trans-tibial amputation, substantially as described with reference to, or as shown in, Figures 4 to 6 of the drawings.

4. A prosthetic leg for use with a trans-tibial amputation, the leg comprising an upper shell flexibly securable to the upper leg, a lower shell for receiving the wearer's stump, the lower shell being attached to a rigid shin member having a prosthetic foot connected thereto, the upper and lower shells being directly pivotally connected together by means of an aligned pair of pivot pins.

5. A prosthetic leg according to Claim 4, wherein the pivot pins are threaded flanged bushes.

6. A prosthetic leg according to Claim 4 or 5, wherein the lower shell is moulded to conform closely with the wearer's stump.

7. A prosthetic leg according to Claim 4 or 5, wherein the lower shell is shaped to receive an inflatable socket which can be adjusted to conform with the wearer's stump.

8. Aprosthetic leg according to Claim 7, wherein the inflatable socket comprises a separately inflatable chamber to provide support for the front of the wearer's knee.

9. A prosthetic leg, substantially as described with reference to, or as shown in, Figures 4 to 6 of the drawings.

Amendments to the claims have been filed as follows

4. A prosthetic leg for use with a trans-tibial amputation, the leg comprising an upper moulded plastics shell flexibly securable to the upper leg, a lower moulded plastics shell for receiving the wearer's stump, the lower shell being attached to a rigid shin member having a prosthetic foot connected thereto, the upper and lower shells being directly pivotally connected together by means of an aligned pair of pivot pins.

8. A prosthetic leg according to Claim 7, wherein the inflatable socket comprises a separately inflatable chamber to provide support for the front of the wearer's knee.