- Email: [email protected]
An improved swivel walker for paraplegics
AN IMPROVEDSWIVELWALKERFORPARAPLEGICS A.G.
Taylor
and L. Rocca
ABSTRACT A swivel walker for adult paraplegics is described greatly reduces the problems involved in donning
which and
doffing. The overall stiffness and stability of the walker has been improved, and early prototypes have had a favourable response from patients,
Keywords: Walking aids, paraplegics, mobility, swivel walker
Some paraplegics find that orthotic mobility devices offer a desirable alternative to the wheelchair, since the vertical position engenders a sense of improved physical and psychological wellbeing. It also increases the range of activities, especially in environments not designed specifically for the wheelchair user. Unfortunately, adults find many of these devices very difficult to get into, and this factor alone accounts for a very high rejection rate of devices that could otherwise make a significant contribution to the patient’s daily activities. This is particularly true for the swivel walker which has proved its value domestically and as an excercise splint1-3. In the Salford Orthopaedic Appliance clinic, 18 paraplegic patients have been fitted with such a device with a varied amount of success. Problems have arisen in putting on the walker and attaining a vertical position. The remarkable agility shown by children in rolling into the walker in the horizontal position and then pulling themselves unaided into the vertical cannot in general be achieved by adults. Modified wheelchairs4, slings and hoist’ have been developed to simplify some of these problems. However, patients find it difficult with existing designs to transfer independently from their own wheelchair into the swivel walker. To perform the transfer from one chair to another the patient is required to lift his own body weight. During this manoeuvre the legs have to be carred across by an assistant so as to avoid injury on the framework of the walker or wheelchair. At home the patient may need to sit in the walker in a wheelchair but, with the present design, would be sitting on parts of the walker that could cause pressure problems. In an attempt to overcome these drawbacks, the authors have redesigned the swivel walker so that it can be donned while the patient is sitting in his wheelchair. In the old model the stiffness of the walker frame was greatly dependent on the rigidity of three cross bands (called the axilla band, hip band and knee band) as shown in Figure l(b). In that case the patient was required to suffer the discomfort of sitting on the sacral pad and centre band. In the new design, all the rigid cross bands Salford Orthopaedic Appliance Unit University of Salford, Salford M5 4WT, UK
0141~5426/82/040325-03 $03.00 0 1982 Butterworth & Co. (Publishers) Ltd
have been moved to the front of the walker as shown in Figure I(a) and 2. The patient is therefore supported in the vertical position by the padded chest band, a sacral support and a padded knee support. The plastic sacral support is moulded to the shape of the buttocks and clipped onto the side members by means of car seat belt buckles, two each side of the frame. (Figure l(b). The device is put on in the following manner: With the walker in a standing position, the patient moves his wheelchair so that he can position his feet on the shoeplates of the appliance and strap them in position. If he then moves forward, the knees will come to rest in the knee supports. The hinges are unlocked and the walker folded at the hips and knees. It will then fit closely over the patient with the chest support falling into place around the rib cage. The plastic sacral support, which is positioned in the wheelchair behind the patient, is clipped on to the side member of the swivel walker by means of the seat belt buckles. The patient is then ready to stand. This can be achieved in the conventional way by straightening out the knees and locking the knee joints. An overhead bar or wall bar can be used by the patient to pull himself into the upright position. A patient standing in the swivel walker is shown in Figure 2. The device can be easily removed in the sitting position by unclipping the sacral support and pushing the frame clear of the body - the feet are lifted off the footplates as the wheelchair is moved backwards. This walker not only makes transfer quicker but is much safer to use. The plastic sacral support is attached to the upper side members of the frame between the hip hinge and axilla This allows the support to be positioned over the lower back and sacral area of the patient when standing and remains in the same position for sitting. It has the added advantage that the subject can sit comfortably on his usual wheelchair cushion and not on part of the swivel walker. Therefore he is able to sit in his wheelchair for long periods whilst wearing the appliance. The stiffness of the framework of the new walker has been improved on the basis of tests carried out
J. Biomed. Eng. 1982, Vol. 4, October
325
An improved swivel walker for pamplegics: A.G. Taylor and L. Rocca
Chest
Sacral
Knee
strap
pad
straps
Shoeplates
Figure l(a) Front loading walking appliance; (b) Salford swive1 walker.
on an experimental walker fitted with strain gauges. This gave us data on the loads developed in the frame while a patient was walking and carrying out other manoeuvres that would be expected during a daily routine. As a result of these tests, the stiffness of the new walker has been improved by fitting aluminium alloy channel section side members and also a more effective ‘A’ frame support to carry lateral loading. The geometry of the lever hinges has been altered to reduce the loading on the components of the hinge and the material of some parts has been changed to reduce wear. The foot bearings have been redesigned to incorporate a commercial steel bearing race which it is hoped will not require attention during the life of the walker. Laboratory tests are being carried out on these bearings to a simulated loading of 280 Ibs (127 kg). DISCUSSION
Figure 2 Patient in front loading walking appliance.
326
J. Bibmed. Eng. 1982,‘Vol. 4, October
In our experience, the swivel walker has proved to be very effective for children and there has long been the need to extend the benefits of this device to adults. In the case of adults, who need or wish to assume the vertical position, the problems involved in using a swivel walker have always been technical and in need of an engineering solution. This modified adult walker may well go
An improved swivel walker for paraplegics: A. G. Taylor and L. Rocca
a long way towards solving these problems and to making the device attractive for a wider range of adult paraplegics and tetraplegics. Patient trials are now proceeding with this new design of swivel walker for three paraplegic adults and two teenage spina bifida patients, where minor individual fitting problems can be overcome. ACKNOWLEDGEMENTS The authors wish to thank Professor J. Edwards, Technical Director and Mr J.C. Griffiths, FRCS, Medical Director of the Salford Orthopaedic Appliance Unit, University of Salford for their help and encouragement in the preparation of this paper.
REFERENCES Henshaw, J.T. The biomechanical design of a walking appliance for a paraplegic adult. J. Med. Engng. Tech. 1977 l(3) 141-145. Griffiths, J.C., Henshaw, J.T., Heywood, O.B. and Taylor, A.G. Clinical applications of the paraplegic swivel walker. j. Biomed. Engng. 1980 Z(4) 250-2.56. Stalla.rd, J., Rose, G.K. and Farmer, I.R. The Orlau swivel walker. Prosthet. Orthot. Intern 1978 2 35-42. Agarwal, K.C. and Henshaw, J.T. A lifting wheelchair for paraplegic patients. j. Med. Engng. Tech 1977 l(6) 347-349. Taylor, A.G., Heywood, PJ. and Rocca, L. A hoist modification to allow a heavy tetraplegic patients in a swivel walker to be lifted. J. Med. Engng. Tech. 1980 4(2) 83.
J. Biomed. Eng. 1982, Vol. 4, October 327
Taylor
and L. Rocca
ABSTRACT A swivel walker for adult paraplegics is described greatly reduces the problems involved in donning
which and
doffing. The overall stiffness and stability of the walker has been improved, and early prototypes have had a favourable response from patients,
Keywords: Walking aids, paraplegics, mobility, swivel walker
Some paraplegics find that orthotic mobility devices offer a desirable alternative to the wheelchair, since the vertical position engenders a sense of improved physical and psychological wellbeing. It also increases the range of activities, especially in environments not designed specifically for the wheelchair user. Unfortunately, adults find many of these devices very difficult to get into, and this factor alone accounts for a very high rejection rate of devices that could otherwise make a significant contribution to the patient’s daily activities. This is particularly true for the swivel walker which has proved its value domestically and as an excercise splint1-3. In the Salford Orthopaedic Appliance clinic, 18 paraplegic patients have been fitted with such a device with a varied amount of success. Problems have arisen in putting on the walker and attaining a vertical position. The remarkable agility shown by children in rolling into the walker in the horizontal position and then pulling themselves unaided into the vertical cannot in general be achieved by adults. Modified wheelchairs4, slings and hoist’ have been developed to simplify some of these problems. However, patients find it difficult with existing designs to transfer independently from their own wheelchair into the swivel walker. To perform the transfer from one chair to another the patient is required to lift his own body weight. During this manoeuvre the legs have to be carred across by an assistant so as to avoid injury on the framework of the walker or wheelchair. At home the patient may need to sit in the walker in a wheelchair but, with the present design, would be sitting on parts of the walker that could cause pressure problems. In an attempt to overcome these drawbacks, the authors have redesigned the swivel walker so that it can be donned while the patient is sitting in his wheelchair. In the old model the stiffness of the walker frame was greatly dependent on the rigidity of three cross bands (called the axilla band, hip band and knee band) as shown in Figure l(b). In that case the patient was required to suffer the discomfort of sitting on the sacral pad and centre band. In the new design, all the rigid cross bands Salford Orthopaedic Appliance Unit University of Salford, Salford M5 4WT, UK
0141~5426/82/040325-03 $03.00 0 1982 Butterworth & Co. (Publishers) Ltd
have been moved to the front of the walker as shown in Figure I(a) and 2. The patient is therefore supported in the vertical position by the padded chest band, a sacral support and a padded knee support. The plastic sacral support is moulded to the shape of the buttocks and clipped onto the side members by means of car seat belt buckles, two each side of the frame. (Figure l(b). The device is put on in the following manner: With the walker in a standing position, the patient moves his wheelchair so that he can position his feet on the shoeplates of the appliance and strap them in position. If he then moves forward, the knees will come to rest in the knee supports. The hinges are unlocked and the walker folded at the hips and knees. It will then fit closely over the patient with the chest support falling into place around the rib cage. The plastic sacral support, which is positioned in the wheelchair behind the patient, is clipped on to the side member of the swivel walker by means of the seat belt buckles. The patient is then ready to stand. This can be achieved in the conventional way by straightening out the knees and locking the knee joints. An overhead bar or wall bar can be used by the patient to pull himself into the upright position. A patient standing in the swivel walker is shown in Figure 2. The device can be easily removed in the sitting position by unclipping the sacral support and pushing the frame clear of the body - the feet are lifted off the footplates as the wheelchair is moved backwards. This walker not only makes transfer quicker but is much safer to use. The plastic sacral support is attached to the upper side members of the frame between the hip hinge and axilla This allows the support to be positioned over the lower back and sacral area of the patient when standing and remains in the same position for sitting. It has the added advantage that the subject can sit comfortably on his usual wheelchair cushion and not on part of the swivel walker. Therefore he is able to sit in his wheelchair for long periods whilst wearing the appliance. The stiffness of the framework of the new walker has been improved on the basis of tests carried out
J. Biomed. Eng. 1982, Vol. 4, October
325
An improved swivel walker for pamplegics: A.G. Taylor and L. Rocca
Chest
Sacral
Knee
strap
pad
straps
Shoeplates
Figure l(a) Front loading walking appliance; (b) Salford swive1 walker.
on an experimental walker fitted with strain gauges. This gave us data on the loads developed in the frame while a patient was walking and carrying out other manoeuvres that would be expected during a daily routine. As a result of these tests, the stiffness of the new walker has been improved by fitting aluminium alloy channel section side members and also a more effective ‘A’ frame support to carry lateral loading. The geometry of the lever hinges has been altered to reduce the loading on the components of the hinge and the material of some parts has been changed to reduce wear. The foot bearings have been redesigned to incorporate a commercial steel bearing race which it is hoped will not require attention during the life of the walker. Laboratory tests are being carried out on these bearings to a simulated loading of 280 Ibs (127 kg). DISCUSSION
Figure 2 Patient in front loading walking appliance.
326
J. Bibmed. Eng. 1982,‘Vol. 4, October
In our experience, the swivel walker has proved to be very effective for children and there has long been the need to extend the benefits of this device to adults. In the case of adults, who need or wish to assume the vertical position, the problems involved in using a swivel walker have always been technical and in need of an engineering solution. This modified adult walker may well go
An improved swivel walker for paraplegics: A. G. Taylor and L. Rocca
a long way towards solving these problems and to making the device attractive for a wider range of adult paraplegics and tetraplegics. Patient trials are now proceeding with this new design of swivel walker for three paraplegic adults and two teenage spina bifida patients, where minor individual fitting problems can be overcome. ACKNOWLEDGEMENTS The authors wish to thank Professor J. Edwards, Technical Director and Mr J.C. Griffiths, FRCS, Medical Director of the Salford Orthopaedic Appliance Unit, University of Salford for their help and encouragement in the preparation of this paper.
REFERENCES Henshaw, J.T. The biomechanical design of a walking appliance for a paraplegic adult. J. Med. Engng. Tech. 1977 l(3) 141-145. Griffiths, J.C., Henshaw, J.T., Heywood, O.B. and Taylor, A.G. Clinical applications of the paraplegic swivel walker. j. Biomed. Engng. 1980 Z(4) 250-2.56. Stalla.rd, J., Rose, G.K. and Farmer, I.R. The Orlau swivel walker. Prosthet. Orthot. Intern 1978 2 35-42. Agarwal, K.C. and Henshaw, J.T. A lifting wheelchair for paraplegic patients. j. Med. Engng. Tech 1977 l(6) 347-349. Taylor, A.G., Heywood, PJ. and Rocca, L. A hoist modification to allow a heavy tetraplegic patients in a swivel walker to be lifted. J. Med. Engng. Tech. 1980 4(2) 83.
J. Biomed. Eng. 1982, Vol. 4, October 327