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Isokinetic and isometric strength of the thigh muscles in below-knee amputees
Clinical Biomechanics Vol. 11, No. 4, pp. 233-235, 1996 Copyright @ 1996 Elsevier Science Limited. All rights reserved Printed in Great Britain 0268-0033196$15.00 + 0.00 ELSEVIER
0268-0033(95)00078-X
Brief Report
lsokinetic and isometric strength of the thigh muscles in below-knee amputees E Isakov
MD,
H Burger2
MD,
M GregoriC2
MD,
C MarinCek2
MD
‘Loewenstein Rehabilitation Hospital, Tel-Aviv University Sackler Faculty of Medicine, Ra’anana, Israel; ‘Institute for Rehabilitation, Ljubljana, Slovenija
Abstract Objective. The strength of the quadriceps and hamstring muscles of the amputated limb in below-knee amputees was evaluated. Design. A descriptive study based on clinical measurements of muscle strength. Background. The residual limb of below-knee amputees is less active in daily functions. As a result, atrophy of the thigh muscles in the affected limb is a common finding. Quality of standing and gait performances depend on the strength of these muscles, which activate the knee of the amputated limb. Methods. lsokinetic concentric and eccentric, as well as isometric, strength of thigh muscles was measured by means of a dynamometer. Parameters of peak torque and maximal average torque of the quadriceps and hamstring muscles were considered. Results. Significant decreases (P
lsokinetic
Clin. Biomech.
and isometric
strength,
Vol. 11, No. 4, 233-235,
quadriceps,
hamstrings,
below-knee
amputees
1996
Introduction Atrophy of the thigh muscles in the amputated limb is often observed among long-standing below-knee (BK) amputees. BK amputation of the limb results in loss of proprioceptive feedback, mainly from the ankle joint and relative muscles’. It is therefore agreed that the residual limb of BK amputees is less active in daily functions of standing and walking2,3. Clinical evaluation of muscle strength is performed by manual testing. However, this technique is inconsistent in application and grading4, the test interrater reliability is poor5 and it gives no information regarding muscle performance. Isokinetic and isoReceived: 16 May 1995; Accepted: 23 November 1995 Correspondence and reprint requests 20: Dr Eli Isakov, Head of
Orthopaedic Rehabilitation Department, Loewenstein Rehabilitation Hospital, Ra’anana 43100, Israel
metric muscle evaluation by means of a dynamometer is an objective reproducible test. Reports confirm its reliability and describe the use of dynamometers for measuring muscle strength in the disabled6,‘. The present study was addressed to evaluate the isokinetic and isometric strength of the quadriceps and hamstrings muscles of the amputated limb in BK amputees and eventual time-related muscle strength since amputation. Methods We assessed18 volunteers, 6 female and 12 males, with below-knee amputation. Their average age was 45.7 years (range 27-74). The mean time from amputation to the present study was 13.4 years (range l-46). Subjects were divided into two equal groups; in the first group amputation had been performed up to 7 years
234
Clin. Biomech.
Vol. 11, No. 4, 1996
earlier and in the second group the amputation had been performed more than 7 years earlier. All subjects were using their prostheses for the whole day and were able to walk continuously for a mean distance of 2.5 km. No subject had any joint contracture or complaints of knee or stump pain during the test.
Table 1. Means (SD) (Nm) of muscles peak torque (isokinetic and maximal average torque (isometric contraction) Type of muscle contraction
Muscles
Isok. concentric: Isok. eccentric: Isometric:
Instruntenrution The isokinetic concentric and eccentric and the isometric muscle torques of the knee extensors and flexors were measured on-line with the Biodex systemh. An adjustable lever was constructed to meet with the special needs of the tested stump, allowing the lever arm to rest at the same distance from the lower pole of the patella in both limbs of each subject. Before each test the gravity correction torque of the limb was measured by asking the subject to completely relax and let the weight of the limb fall against the lever’s pad. The dynamometer was calibrated according to the manufacturer’s recommendations, and this was done once weekly.
The patients were seated with hip joints angle of 90100 degrees. Stabilization straps were placed across the trunk, around the waist, and mid-thigh of the limb to be tested. The anatomical axis of the knee joint was aligned with the axis of rotation of the dynamometer. Prior to each test subjects were instructed and allowed to try the dynamometer, performing a submaximal contraction in order to become acquainted with the exercise. The test procedure consisted of five consecutive isokinetic concentric contractions for the quadriceps and hamstrings muscles groups, followed by five eccentric contractions with 5 min rest. The constant angular velocity was established on 60 deg per second. Following S min rest, each subject performed five consecutive isometric contractions of 5 s each. The quadriceps contractions was evaluated at 45 deg of flexion and the hamstrings contraction at 60 deg of fexion. Muscles of both limbs were evaluated and subjects were asked to perform their maximal effort and verbal encouragement was provided to each subject throughout the test sessions. Peak torque is the highest value of torque, in Nm, developed throughout the range of motion curve. Maximal average torque is the greatest average torque produced for a repetition within a set.
Q H Q H Q H
Sound limb 76.7 74.6 171.2 128.2 93.0 52.6
Amput limb
(31) 40.4 (20) (34) 29.9 (20) (45) 112.0 (47) (45) 64.5 (37) (34) 46.0 (26) (24) 30.3 (20)
contraction)
P
Diff. 1%)
0.001 0.001 0.002 0.001 0.001 0.007
47 60 35 50 51 42
(Q, quadriceps; H, hamstrings).’
contractions for the quadriceps and hamstrings in the sound limb were compared with those of the amputated limb (Table 1). Parameters of peak torque (isokinetic contraction) and maximal average torque (isometric contraction) of extension and flexion of the knees were considered. Differences between the limbs were significant (P
Table2. maximal muscles
Means (SD) (Nm) of peak torque (isokinetic contraction) and of average torque (isometric contraction) of the amputated thigh
Time since amputation Tested muscle and type of exercise
< 7 years In = 9)
> 7 years In = 9)
The significance of the results was performed by the paired t-test and level of significance was set at 5%.
Quadriceps Isok. concentric Isok. eccentric Isometric
43.5 (20.2) 115.7 (50.9) 49.3 (21.8)
37.3 (21.8) 108.4 (45.9) 42.7 (31.3)
Results
Hamstrings Isok. concentric Isok. eccentric Isometric
32.1 (22.4) 67.8 (46.4) 35.6 (25.4)
27.7 (18.4) 61.2 (27.8) 25.1 (13.5)
Means and standard deviations of values obtained following isokinetic concentric and isokinetic eccentric
Compared are two groups; less vs. over 7 years since amputation. between the two groups were found to be non-significant.
Differences
lsakov et al.: Strength
(more than 7 years). Although a decrease in strength was found mostly in the veteran amputees, differences between the quadriceps and hamstrings of both limbs were insignificant. We can therefore assume that the main reduction in thigh muscles strength takes place during the first few years after amputation. In conclusion, although most below-knee amputees manage their activities of daily living and conduct a fairly active life, the residual limb thigh muscles strength were found significantly reduced. We therefore assume that these subjects might benefit from strengthening exercises applied to the thigh muscles. Acknowledgement The authors would like to thank Mr Tomsii- Igor for his help with the Biodex measurements and Mr Bevetek Tomai for his assistance during the testing procedures.
of thigh muscles
in below-knee
amputees
235
References 1 Geurts AC, Mulder TW. Reorganisation of postural control following lower limb amputation: theoretical considerations and implications for rehabilitation. Phys Theory Pratt 1992; 8: 145-57 2 Renstrom P, Grimby G, Larsson E. Thigh muscle strength in below-knee amputees. Stand J Rehabil Med 1983; 9[Suppl]: 161-73 3 Isakov E, Mizrahi J, Ring H et al. Standing sway and weight-bearing distribution in below-knee amputees. Arch Phys Med Rehabill992; 73: 174-8 4 Nicholas J, SapegaA, Kraus H, Webb J. Factors influencing manual tests in physical therapy. J Bone Joint Surg 1978: 60A: 186-91 5 Iddlings D, Smith L, Spencer W. Muscle testing, Pt 2: Reliability in clinical use. Phys Ther Rev 1961; 41: 249-53 6 Wilk KE, Johnson RE. The reliability of the Biodex B-2000. Phys Ther 1988; 68: 792-7 7 Steiner LA, Harris BA, Krebs DE. Reliability of eccentric isokinetic knee flexion and extension measurements. Arch Phys Med Rehabill993; 74: 1327-3.5
0268-0033(95)00078-X
Brief Report
lsokinetic and isometric strength of the thigh muscles in below-knee amputees E Isakov
MD,
H Burger2
MD,
M GregoriC2
MD,
C MarinCek2
MD
‘Loewenstein Rehabilitation Hospital, Tel-Aviv University Sackler Faculty of Medicine, Ra’anana, Israel; ‘Institute for Rehabilitation, Ljubljana, Slovenija
Abstract Objective. The strength of the quadriceps and hamstring muscles of the amputated limb in below-knee amputees was evaluated. Design. A descriptive study based on clinical measurements of muscle strength. Background. The residual limb of below-knee amputees is less active in daily functions. As a result, atrophy of the thigh muscles in the affected limb is a common finding. Quality of standing and gait performances depend on the strength of these muscles, which activate the knee of the amputated limb. Methods. lsokinetic concentric and eccentric, as well as isometric, strength of thigh muscles was measured by means of a dynamometer. Parameters of peak torque and maximal average torque of the quadriceps and hamstring muscles were considered. Results. Significant decreases (P
lsokinetic
Clin. Biomech.
and isometric
strength,
Vol. 11, No. 4, 233-235,
quadriceps,
hamstrings,
below-knee
amputees
1996
Introduction Atrophy of the thigh muscles in the amputated limb is often observed among long-standing below-knee (BK) amputees. BK amputation of the limb results in loss of proprioceptive feedback, mainly from the ankle joint and relative muscles’. It is therefore agreed that the residual limb of BK amputees is less active in daily functions of standing and walking2,3. Clinical evaluation of muscle strength is performed by manual testing. However, this technique is inconsistent in application and grading4, the test interrater reliability is poor5 and it gives no information regarding muscle performance. Isokinetic and isoReceived: 16 May 1995; Accepted: 23 November 1995 Correspondence and reprint requests 20: Dr Eli Isakov, Head of
Orthopaedic Rehabilitation Department, Loewenstein Rehabilitation Hospital, Ra’anana 43100, Israel
metric muscle evaluation by means of a dynamometer is an objective reproducible test. Reports confirm its reliability and describe the use of dynamometers for measuring muscle strength in the disabled6,‘. The present study was addressed to evaluate the isokinetic and isometric strength of the quadriceps and hamstrings muscles of the amputated limb in BK amputees and eventual time-related muscle strength since amputation. Methods We assessed18 volunteers, 6 female and 12 males, with below-knee amputation. Their average age was 45.7 years (range 27-74). The mean time from amputation to the present study was 13.4 years (range l-46). Subjects were divided into two equal groups; in the first group amputation had been performed up to 7 years
234
Clin. Biomech.
Vol. 11, No. 4, 1996
earlier and in the second group the amputation had been performed more than 7 years earlier. All subjects were using their prostheses for the whole day and were able to walk continuously for a mean distance of 2.5 km. No subject had any joint contracture or complaints of knee or stump pain during the test.
Table 1. Means (SD) (Nm) of muscles peak torque (isokinetic and maximal average torque (isometric contraction) Type of muscle contraction
Muscles
Isok. concentric: Isok. eccentric: Isometric:
Instruntenrution The isokinetic concentric and eccentric and the isometric muscle torques of the knee extensors and flexors were measured on-line with the Biodex systemh. An adjustable lever was constructed to meet with the special needs of the tested stump, allowing the lever arm to rest at the same distance from the lower pole of the patella in both limbs of each subject. Before each test the gravity correction torque of the limb was measured by asking the subject to completely relax and let the weight of the limb fall against the lever’s pad. The dynamometer was calibrated according to the manufacturer’s recommendations, and this was done once weekly.
The patients were seated with hip joints angle of 90100 degrees. Stabilization straps were placed across the trunk, around the waist, and mid-thigh of the limb to be tested. The anatomical axis of the knee joint was aligned with the axis of rotation of the dynamometer. Prior to each test subjects were instructed and allowed to try the dynamometer, performing a submaximal contraction in order to become acquainted with the exercise. The test procedure consisted of five consecutive isokinetic concentric contractions for the quadriceps and hamstrings muscles groups, followed by five eccentric contractions with 5 min rest. The constant angular velocity was established on 60 deg per second. Following S min rest, each subject performed five consecutive isometric contractions of 5 s each. The quadriceps contractions was evaluated at 45 deg of flexion and the hamstrings contraction at 60 deg of fexion. Muscles of both limbs were evaluated and subjects were asked to perform their maximal effort and verbal encouragement was provided to each subject throughout the test sessions. Peak torque is the highest value of torque, in Nm, developed throughout the range of motion curve. Maximal average torque is the greatest average torque produced for a repetition within a set.
Q H Q H Q H
Sound limb 76.7 74.6 171.2 128.2 93.0 52.6
Amput limb
(31) 40.4 (20) (34) 29.9 (20) (45) 112.0 (47) (45) 64.5 (37) (34) 46.0 (26) (24) 30.3 (20)
contraction)
P
Diff. 1%)
0.001 0.001 0.002 0.001 0.001 0.007
47 60 35 50 51 42
(Q, quadriceps; H, hamstrings).’
contractions for the quadriceps and hamstrings in the sound limb were compared with those of the amputated limb (Table 1). Parameters of peak torque (isokinetic contraction) and maximal average torque (isometric contraction) of extension and flexion of the knees were considered. Differences between the limbs were significant (P
Table2. maximal muscles
Means (SD) (Nm) of peak torque (isokinetic contraction) and of average torque (isometric contraction) of the amputated thigh
Time since amputation Tested muscle and type of exercise
< 7 years In = 9)
> 7 years In = 9)
The significance of the results was performed by the paired t-test and level of significance was set at 5%.
Quadriceps Isok. concentric Isok. eccentric Isometric
43.5 (20.2) 115.7 (50.9) 49.3 (21.8)
37.3 (21.8) 108.4 (45.9) 42.7 (31.3)
Results
Hamstrings Isok. concentric Isok. eccentric Isometric
32.1 (22.4) 67.8 (46.4) 35.6 (25.4)
27.7 (18.4) 61.2 (27.8) 25.1 (13.5)
Means and standard deviations of values obtained following isokinetic concentric and isokinetic eccentric
Compared are two groups; less vs. over 7 years since amputation. between the two groups were found to be non-significant.
Differences
lsakov et al.: Strength
(more than 7 years). Although a decrease in strength was found mostly in the veteran amputees, differences between the quadriceps and hamstrings of both limbs were insignificant. We can therefore assume that the main reduction in thigh muscles strength takes place during the first few years after amputation. In conclusion, although most below-knee amputees manage their activities of daily living and conduct a fairly active life, the residual limb thigh muscles strength were found significantly reduced. We therefore assume that these subjects might benefit from strengthening exercises applied to the thigh muscles. Acknowledgement The authors would like to thank Mr Tomsii- Igor for his help with the Biodex measurements and Mr Bevetek Tomai for his assistance during the testing procedures.
of thigh muscles
in below-knee
amputees
235
References 1 Geurts AC, Mulder TW. Reorganisation of postural control following lower limb amputation: theoretical considerations and implications for rehabilitation. Phys Theory Pratt 1992; 8: 145-57 2 Renstrom P, Grimby G, Larsson E. Thigh muscle strength in below-knee amputees. Stand J Rehabil Med 1983; 9[Suppl]: 161-73 3 Isakov E, Mizrahi J, Ring H et al. Standing sway and weight-bearing distribution in below-knee amputees. Arch Phys Med Rehabill992; 73: 174-8 4 Nicholas J, SapegaA, Kraus H, Webb J. Factors influencing manual tests in physical therapy. J Bone Joint Surg 1978: 60A: 186-91 5 Iddlings D, Smith L, Spencer W. Muscle testing, Pt 2: Reliability in clinical use. Phys Ther Rev 1961; 41: 249-53 6 Wilk KE, Johnson RE. The reliability of the Biodex B-2000. Phys Ther 1988; 68: 792-7 7 Steiner LA, Harris BA, Krebs DE. Reliability of eccentric isokinetic knee flexion and extension measurements. Arch Phys Med Rehabill993; 74: 1327-3.5