Amputee Exercise Equipment

In 1985 I was in a car crash in which I was the guy on the motorbike, as a result I lost my right leg 7 inches below the knee.

Complications developed within 12 months. Growth of bone spurs, had occurred, causing significant pain and eventually needing surgery. On closer exploration a large cyst was discovered and removed.

The following year, still unable to walk the bone spurs were removed. I spent almost 6 years in some state of incapacity and most of it on crutches.

I went this whole time without any fixed rehabilitation or Exercise programme implemented. (This sort of thing doesn't happen as much these days)

This meant when I came to walk with my new prosthesis, my residual limb was so weak that i was suffering from muscle fatigue and would regularly trip and fumble.(I really needed some sort of muscle building exercise)

The best I was offered was a piece of elastic band off a large roll. The problem with this was my now short stump would not allow for this giant rubber band to be attached to me in an effective way.

Finding there was no Amputee Exercise Equipment available to me but wanting to get fit, I started designing my own Amputee Exercise Machines.

After a lot of research, the conducting of Literature Reviews, the design of several Amputee Specific Exercise Machines and clinical trials.
"Hydraujoint(TM) Ltd" was founded.

A copy of the first literature review is below.

Exercise for Trans-tibial Amputees.

Introduction

In late 2002, Stephen Kemp, Managing Director of  Hydraujoint Ltd, himself a trans-tibial amputee, approached John Henley-King of Massey University Research Services about the possibility of obtaining some assistance with the design and prototyping of an exercise device to improve muscle strength and functional capacity of amputees. The device is intended to be used by amputees in their own home in an unsupervised setting, and so must be inherently safe and easy to use. As a first step in this process, this literature review has been compiled to provide a basis for design and development. The review will address the issues of the relationship between muscle strength and functional capacity in trans-tibial amputees, and will touch briefly on the incidence and control of phantom pain.

Literature review

Reduction in thigh muscle strength in trans-tibial amputees has been shown to be highly correlated with muscle atrophy and reduction in clinical function (Renstorm, Grimby, & Larsson, 1983). In this study,thirty-two trans-tibial amputees participated in examinations of the isometric and isokinetic  knee extension and flexion strength, and a degree of atrophy of the thigh muscles were measured in trans-tibial amputees. The muscle strength in the amputated leg with and without prosthesis was significantly lower than the strength of the non amputated leg. Knee extension strength was correlated to the mean muscle fibre area of the vastus lateralis, but there was no correlation between strength and the cross sectional area of the quadriceps muscles. The reduction in knee extension and flexion strength  in the amputated leg both with and without prosthesis compared with the non amputated leg was larger than the reduction in cross sectional areas of the quadriceps and hamstring muscles, which could indicate that other factors such as changes in motor unit recruitment patterns are important in the reduction of muscle strength. Isometric and isokinetic knee extension and flexion strength values in the amputated leg with prosthesis were significantly correlated to step length, maximal walking speed and circumference of thigh. Because step length is a major determinant of walking speed and efficiency, this result indicates that trans-tibial amputees with improved thigh muscle strength will have better walking capacity.

Muscle strength has been shown to be an important factor in fall prevention in the elderly. Hurley and Roth (Hurley & Roth, 2000) indicate that strength training in the elderly, among other things:

1.     produces substantial increases in the strength, mass, power and quality of skelatal muscle;

2.     can increase endurance performance;

3.     normalises blood pressure in those with high normal values;

4.     reduces insulin resistance;

5.     decreases both total and intra-abdominal fat;

6.     reduces risk factors for falls; and

7.     may reduce pain and improve function in those with osteoarthritis in the knee region.

In recent studies in New Zealand (Campbell,Borrie, & Spiers, 1989) it has been shown that a low intensity, community based exercise program including strength training reduces the risk of falling in adults. The incidence and fear of falling is pervasive among amputees, and Miller and co-workers (Miller, Deathe, Speechley, & Koval, 2001; Miller, Speechley, & Deathe, 2001) showed that balance confidence was a major protective factor. Thigh muscle strength is a major determinant of balance confidence, and so improvement of thigh muscle strength in amputees would be expected to improve balance, and so reduce the incidents of falls.

The gait of the trans-tibial amputees is significantly different from that of non-amputees, in particular, stride length is lower, and preferred walking speed is slower. These differences have been shown to resemble the effect of additional load on the ankle of a normal walker (Eke-Okoro, 1999). That is, the knee flexor and extensor muscles must exert larger forces in the amputee to compensate for the lack of ankle torques. There is some rather inconsistent evidence that a slightly increased moment of inertia reduces the work required by the knee extensors during late swing phase of gait (Hillery & Wallace, 2000).

In normal walking, the gait on left and right sides is highly symmetrical. This symmetry is not observed in amputees. In general, step length, step time and swing time are significantly longer on the amputated side, while stance time and single support time are significantly shorter on the amputated side (Isakov, Keren, & Benjuya, 2000). Isakov et al also found large differences in muscle timing and relative activation between the sound and amputated limbs which they attributed to the prosthetic foot impeding forward motion in early swing phase and the need to support the knee on the amputated side in early stance (Isakov, Burger, Krajnik, Gregoric, & Marincek, 2001).

The absence of  ankle plantar-flexion muscles has been considered a major disability in amputee gait because these are the major producers of forward propulsion. The amputee overcomes this problem by using other muscles or changing the characteristics of gait (Michel & Do, 2002). One of the strategies most often observed to achieve this is “Hip-hiking” (increasing the angle of the pelvis in the frontal plane during swing phase). This strategy has quite serious consequences for walking duration because it rapidly fatigues the hip abductor muscles. It has been shown that those amputees with strong hip abductor muscles display increased weight bearing on the amputated limb, improved gait parameters, and reduced medio-lateral excursion of the centre of pressure under the amputated limb (Nadollek, Brauer, & Isles, (2002). Nadollek at al conclude that:

This research confirms the asymmetrical nature of amputee stance and demonstrates symmetry of strength and gait measures between limbs. The correlations between hip and abductor strength, weight distribution and gait measures illustrates the importance of training these muscles.

It is generally accepted that the energy cost of walking with a lower-limb prosthesis is higher than that of normal walking, and that the extra energy required may be reduced by appropriate physical conditioning (Ward & Meyers, 1995). Endurance has been shown to be effective in increasing VO2max, anaerobic threshold, and maximum workload for amputees, to a point where there is no significant difference from normal control subjects. An appropriate programme based on individual anaerobic threshold has been shown to be effective in this respect (Chin et al., 2001). Because the metabolic cost of walking is high for amputees, and they are generally less fit than normal control subjects, amputee walking endurance is much lower than that of a non-amputee. Walking endurance is a useful measure of functional capacity in lower-limb amputees, and is often measured usin the two-minute walk test. This is a simple test that measures the total distance walked in two minutes at a self-selected pace, and been proven reliable and sensitive to the effects of rehabilitation and physical training (Brooks et al., 2002; Brooks, Parsons, Hunter, Delvin, & Walker, 2001)

Strength training of the knee muscles in trans-tibial amutees at several fixed angular speeds has demonstrated increases in both size of knee extensor and flexor muscles and their ability to produce force (Klingenstierna, Renstorm, Grimby, & Morelli, 1990). In this study, the intact leg was also trained, but did not demonstrate the magnetude of chabges found in the amputated limb. The subjects reported that they could walk more than twice the distance achieved before training and could manage better without mobility aids. The study also indicated a larger increase in the size and strength of type II (fast twitch, anaerobic) fibres compared with type I fibres, which indicates that the training forces were sufficient to activate almost all the motor units in the muscle.

In a similar study, Moirenfield et al (Moirenfield, Ayalon, Ben-Sira, & Isakov, 2000) measured concentric strength and endurance of the thigh muscles using an isokinetic dynamometer. They found that peak tourque for extension and flexion was significantly higher in the sound limb, and that the fatigue index for flexion torque was significantly higher in the sound limb(p<0.01) which they attributed to the degree of muscle atrophy on the amputated side. They concluded that:

It is of great importance to reduce the bilateral deficit and the degree of atrophy as soon as possible in order to improve the level of performance. By choosing a correct strength and endurance training programme, one may expect to get a significant and good reaction from the muscles of the amputated limb as is expected from training the muscles of a sound limb.   

Many exercise regimes and training programmes have been found helpful in the process of rehabilitation of amputees and reintegration to the workforce. These may be divided into four main components: flexibility, muscle strength, cardiovascular training, and balance gait (Esquenazi & DiGiacomo, 2001). Kegal at al (Kegal, Burgess, Starr, & Daly, 1981) showed that the use of biofeedback in a controlled isometric exercise program produced increase in muscle bulk below the knee. Isokentic (constant speed) exercise has been shown to be effective in increasing strength of debilitated muscles. However, this is usually achieved using specific, and usually very expensive, isokinetic dynamometer that was designed for use by non-amputees. Consequently, amputees find this device difficult to us, even if they are able to gain access to one. Modifications to an isokinetic dynamometer to allow use by trans-tibial amputees with short stumps were described by Marin and co-workers (Marin, Spellman, Kenyon, & Belandres, 1992) and it appears that most practitioners would consider modification of existing exercise equipment as a first step in achieving an appropriate exercise regime for trans-tibial amputees.

There is a large body of literature on the incidence of phantom pain and stump pain in amputees, but there appears to be very little published research dealing with the effect of exercise on either phantom pain or stump pain. A recent study (Nikoljsen & Staehelin Jenson, 2000) concludes:

Phantom pain is experienced by 60% to 80% of patients following limb amputation but is only severe in about 5% to 10% of cases. The mechanisms underlying pain in amputees are not fully understood, but factors in both the peripheral and central nervous system play a role.

A recent paper (Vichitrananda & Pausawasdi, 2001) has reported relief from severe phantom limb pain using Midazolam (a benzodiazepine) which acts to enhance the action of the glycine (also an inhibitory neurotransmitter) on receptors in the spinal neurons. This result may indicate that the pain results from the imbalance of self-sustaining neural activity exceeding inhibitory control. Consequently, it is feasible that an appropriate exercise regime could ameliorate the incidence of  both phantom pain and stump pain by affecting cortical reorganisation and peripheral neural circuits involved in physical activity.

Conclusions

1.     Trans-tibial amputees would benefit from both general physical fitness training and strength endurance training of knee flexor and extensor muscles and hip abductor muscles.

2.     Reduction in gait asymmetry may be achieved by increasing muscular strength and endurance in the amputated limb.

3.     Improvements in muscular strength and endurance will result in enhanced functional capacity in trans-tibial amputees as measured by the two minute walk test.

4.     The design of any exercise device to improve muscular and endurance must allow for use by amputees with short stumps and must accommodate training of the hip abductor muscles in addition to the knee flexors and extensors.

5.     The effect of any strength or exercise programme on the incidence and severity of phantom pain is, at present, unknown.

Alan Walmsley PhD

IFNHH

Massey University

Wellington

28 April 2003    

References

Brooks, D., Hunter, J. P., Parsons, J., Livsey, E., Quirt., J., & Devlin, M. (2002).                     Reliability of the two-minute walk test in individuals with trans-tibial   amputation. Archives of Physical Medicine and Rehabilitation, 83(11),1562-            1565.

Brooks, D., Parsons, J., Hunter, J. P., Devlin, M., & Walker, J.(2001). The 2-minute   walk test as a measure of functional improvement in persons with lower limb            amputation. Archives of Physical Medicine & Rehabilitation, 82(10),1478-   1483.

Campbell, A. J., Borrie, M.J., & Spears, G. F.(1989). Risk factors for falls in a             community-based prospective study of people 70 years and older. Journal of          gerontology, 44(4), M112-117.

Chin, T., Sawamura, S., Fujita, H., Nakajima, S., Ojima, I., Oyabu, H., et al.(2001).    Effect of endurance training program based on anaerobic threshold (AT) for lower-limb amputees. Journal of Rehabilitation Research & Development.,             38(1),7-11.

Eke-okoro, S. T. (1999). Exploration of paretic gait by differential loading in normals.

            Clinical Biomechanics, 14(2), 136-140.

Esquenazi, A., & DiGiacomo, R. (2001). Rehabilitation after amputation. Journal of     the American Podiatric Medical Association, 91(1), 13-22.

Hillery, S. C., & Wallace, E.S. (2000). Trans-tibial amputee gait adaptations as a result             of  prosthetic inertial manipulation. Disability & Rehabilitation, 22(8), 383- 386.    

Hurley, B. F., & Roth, S. M. (2000). Strength training in the elderly: effects on risk        factors for age-related diseases. Sports Medicine. 30(4). 249-268.

Isakov, E., Burger, H., Krajnik, J., Gregoric, M., & Marincek, C. (2001). Knee muscle            activity during ambulation of trans-tibial amputees. Journal of Rehabilitation           Medicine, 33(5), 196-199.

Isakov, E., Keren, O., & Benjuya, N. (2000). Trans-tibial amputee gait: time-distance   parameters and EMG activity. Prosthetics & Orthotics International, 24(3), 21-220.

Kegel, B., Burgess, E. M., Starr, T. W., & Daly, W. K (1981). Effects of isometric      muscle training on residual limb volume, strength, and gait of below-knee           amputees. Physical Therapy, 61(10), 1419-1426.

Klingenstierna, U., Renstrom, P., Grimby, G., & Morelli, B. (1990). Isokinetic strength training in below-knee amputees. Scandinavian Journal Of        Rehabilitation Medicine, 22(1), 39-43.

Marin, R., Spellman, N., Kenyon, M., & Belandres, P. V. (1992) Isokinetic exercise    system modification for short below-the-knee residual limbs. Archives of       Physical Medicine & Rehabilitation., 73(9) 883-885.

Michel, V., & Do, M. C. (2002). Are stance ankle plantar flexor muscles necessary to generate propulsive force during human gait initiation? Neuroscience Letters,     325(2), 139-143.

Miller, W. C., Deathe, A. B., Speechley, M., & Koval, J. (2001). The influence of        falling, fear of falling and balance confidence on prosthetic mobility and activity     among individuals with a lower extremity amputation. Archives of Physical                        Medicine and Rehabilitation, 82(9), 12-38-1244.

Miller, W. C., Speechley, M., & Deathe, B. (2001). The Prevalence and risk factors of falling and fear of falling among lower extremity amputees. Archives of             physical Medicine and Rehabilitation, 82(8), 1031-1037.

Moirenfeld, I., Ayalon, M., Ben-Sira, D., & Isakov, E. (2000). Isokinetic strength and  endurance of the knee extensors and flexors in trans-tibial amputees.                   Prosthetics & Orthotics International, 24(3), 221-225.

Nadollek, H., Brauer, S., & Isles, R. (2002). Outcomes after trans-tibial amputation:      the relationship between quiet stance ability, strength of hip abductor muscle    and gait. Physiotherapy Research International, (4), 203-214.

Nikolajsen, L., & Staehelin Jensen, T. (2000). Phantom limb pain. Current Review of  pain, 4(2), 166-170.  

Renstrom, P., Grimby, G., & Larsson, E. (1983). Thigh muscle strength in below-knee amputees. Scandinavian Journal of Rehabilitation Medicine- Supplementum,   9, 163-173.

Vichitrananda, C., & Pausawasdi, S. (2001). Midazolam for the treatment of phantom   limb pain exacerbation: preliminary reports. Journal of the Medical                                   Association of Thailand, 84(2), 299-302.

Ward, K. H., & Meyers, M. C. (1995). Exercise performance of lower-extremity                     amputees. Sports Medicine., 20(4), 207-214.