Amputation of lower limb causes a series of changes and concomitant adjustments which are related not only to the mutilated limb but also to the entire body [
The sensorimotor system with its complex mechanisms includes the term of proprioception according to an earlier definition. This intricate process involves the transport of information to the central nervous system, relative to the sense of joint position in space, the feeling of power that develops in the joint (sense of force) through specialized sensory receptors, and kinesthesia, videlicet the sense of motion of the joint [
Above-knee amputations result in a loss of a significant number of mechanoreceptors of the knee and generally of the lower limb [
The disruption of the proprioceptive information from the lower limb is followed by central nervous system reorganization, at all levels, from the spinal cord to the cerebral hemispheres, as well as of the afferent and efferent pathways that control and coordinate the movement of the limb [
Significant changes are also observed in balance and gait of patients who suffered from lower limb amputation with asymmetrical weight distribution and shift forward and increased risk of falls [
The aim of the present prospective study was to evaluate knee proprioception using the joint position sense (JPS) method, in the limb that underwent above-knee amputation and has an artificial prosthesis for a considerable period of time, and to estimate the adjustments that have been achieved. In this study the predetermined angle of 15° was chosen as the target angle since it is considered to be functional during gait both in stance and the beginning of swing phase [
The evaluation of the data extracted from this study could contribute to better understanding of the complex proprioceptive mechanisms characterizing the study participants. Furthermore it could conduct to the construction of improved artificial prostheses for these patients and to the creation of optimal rehabilitation programmes.
Participants were selected from an initial group of 25 patients with unilateral lower limb amputation. Eventually 22 individuals were recruited, 18 men and 4 women, aged 24–65 years with an average of 42 years (SD: 11.52) who qualified the required criteria (Table
Demographics.
|
||
---|---|---|
Height of femoral amputation | Cause of amputation | Type of prosthesis |
Lower third |
Traffic accident |
Hydraulic 10 |
Medial femur 7 |
|
C-leg: 10 |
Medial femur-lower third |
Occupational injury 1 | Multiaxial 2 |
These patients had undergone amputation above the knee and under the hip and had used artificial prosthesis for at least one year from the amputation [
Exclusion criteria were bilateral lower or upper limb amputation, problems in auditory and visual system, pain in the stump, alcohol abuse, psychiatric diseases, and the presence of disturbed brain functions or other neurological deficiencies.
Eleven of the patients had undergone an amputation at the lower third of the femoral bone, 7 of them at the medial femur and the remaining 4 at the limit of the medial femur and the lower third of it.
As regards the cause of the amputation, in 18 patients it was a traffic accident; in 2 of them the presence of malignances and in the remaining one the past history revealed an occupational injury.
Relative to the type of the prosthesis 10 of them are characterized by hydraulic knee joint system, 10 of them by electronic C-leg, and the other 2 by a simple multiaxial knee joint (Table
The proprioceptive sensation of the knee was counted with the reproduction of a predetermined angle method (joint position sense) [
According to the width and the length of the patient’s step as it was previously determined two analogical scales were placed within the parallel bars in order to specify the exact position of the center of the weight both in the artificial and the normal joint. It was found that the artificial joint carries the center of the gravity in a different place in comparison with the normal knee, and as a result the gravity line stays within the base of support during gait so that the risk of falls will not increase [
Joint position sense (JPS) evaluation.
The comparison of the variables between the healthy and the amputated limb was performed using the
All measurements were performed by the same researcher. The reliability of the researcher who conducted the measurements was checked and confirmed. The investigator was requested to measure a specific angle which was ultimately compared to an angle that a second independent researcher was asked to measure. The angles were equivalent and were both specific and unknown to both researchers.
Both investigators obtained the same data so the correlation between their measurements for the specific angle proved to be strong (correlation coefficient = 1.00) at a statistical significance level of
For the calculation of the measuring angle, apart from the G300 goniometer, a modern isokinetic Con-Trex dynamometer was used, in which a femorotibial functional brace was fitted and the flexion of the knee was performed according to the angle of the isokinetic dynamometer, on the axis that this guide offered.
This study has been approved by the ethics committee of the hospital where it was performed, while all participants granted a written consent that they agreed to be included in the study.
Out of 22 patients who participated in the study, 11 of them (50%) had undergone amputation of their dominant leg, while in the remaining 11 the amputation regarded the nondominant leg.
As regards the amputated leg, the values of JSP 15° ranged between 4° and 22.7° with mean 13.91 and SD ±4.74, while for the healthy leg the corresponding values ranged between 10° and 19.7° with mean 14.15° and SD ±2.61° (Table
Joint position sense. Comparison between health and amputated leg.
Healthy leg |
Amputated leg |
|
|
---|---|---|---|
1 | 17.3 | 18 | |
2 | 14.7 | 17.3 | |
3 | 10 | 16.3 | |
4 | 15 | 22.7 | |
5 | 18 | 19.7 | |
6 | 10.3 | 10.3 | |
7 | 16 | 19.7 | |
8 | 11.7 | 11.7 | |
9 | 14 | 12.3 | |
10 | 13 | 7.7 | |
11 | 16 | 20 | 0.2584 |
12 | 12 | 6.3 | |
13 | 16 | 13.7 | |
14 | 19.7 | 14.7 | |
15 | 14 | 15.3 | |
16 | 10 | 13 | |
17 | 15.3 | 13.3 | |
18 | 16.7 | 11.7 | |
19 | 12 | 16.7 | |
20 | 13.7 | 9 | |
21 | 12.7 | 12.7 | |
22 | 13.3 | 4 | |
M: 14.15, SD: |
M: 13.91, SD: |
No statistically significant difference was detected amongst the values of the amputated limbs and the healthy limbs (
The measured values in the affected limb differentiated according to the patient’s age when he undergone the amputation and the years that he lived with the artificial joint. Patients that used more years the prosthesis presented improved values of proprioceptive sensation.
Moreover statistically significant differences were not recorded in the measured values between the two prevailing those of prosthesis fitted in the study participants (
Joint position sense. Comparison between hydraulic and C-leg prosthesis.
Prosthesis |
|
Mean age | Min. | Max. | M | SD |
|
---|---|---|---|---|---|---|---|
Hydraulic | 10 | 45.6 | 4 | 13.43 | 18 | 4.31 | −0.942 |
C-Leg | 10 | 37 | 7.7 | 15.38 | 22 | 4.93 |
As regards the reliability of these measurements, it is a considered satisfactory since the value a (coefficient alpha) for the above-mentioned measurements was found greater than 0.80 and precisely equal to 0.95 and 0.97 for the healthy and the operated lower extremity [
In this research paper, we studied the proprioceptive sensation of the lower limb, with the active reproduction of a predetermined angle method, in a closed kinetic chain environment, using the healthy limb like an internal control group. This angle was selected because it is a representative angle within the functional range of 10° to 60° flexion of the knee, which is required for the normal gait, both for the stance phase and for the beginning of the swing phase [
As it is obvious by the result analysis, a statistically significant difference in the values amongst the limb with the artificial joint and the healthy limb was not reported.
This fact suggests that albeit the study participants showed decreased value of proprioceptive sensation to a certain degree, they did not present a serious decrease of proprioceptive information of the lower limb and more specifically the knee joint, after an above-knee amputation and placement of a prosthesis, for at least one year.
These results are in accordance with the findings of previous researchers, who did not record significant decrease as well, as regards the Joint Position Sense (JPS) after amputation and placement of an artificial joint [
Eakin et al. measured the ability of passive reproduction of a predetermined angle in flexion in 5°, 10°, 15°, 20°, and 25°, in an environment of closed kinetic chain. The researchers could not detect significant proprioceptive deficits as regards the target angles and relative to the healthy leg with the previous method. On the contrary, a reduced proprioceptive sensation was recorded in the limb with the prosthesis with the detection of passive motion pathway method [
Similar results were recorded by Liao and Skinner in patients with below-knee amputations, who were evaluated for the sense of the joint position in space, and the kinesthetic perception of the knee joint. In that trial not a significant decrease of the proprioceptive information was recorded by measuring the patient’s ability to reproduce a predetermined angle with the amputated limb, while even in that study decreased values of kinesthesia characterizing the amputated limb are detected as well [
It seems that people with above-knee amputations compensate the loss of the knee joint and the subsequent loss of the mechanoreceptors, via alternative mechanisms that guard the sense of the artificial knee joint.
These mechanisms probably include the hip joint and the cutaneous receptors of the stump which receive impulses from the pressure exerted by the prosthesis [
The proprioceptive ability presented increased in this study, when related to the time passed from the amputation and the placement of the prosthesis, a fact that suggests the development of compensatory mechanisms of the loss of the anatomical structures that enhance the proprioceptive sensation of the lower limb as time passes [
The role of the adjacent joints in the maintenance of the kinesthetic information seems to be very important. Dhillon et al., in patients with amputation above elbow, at least 4 years ago, reported that the remaining functional connections are viable or able to recover after exercise. Furthermore, sensory neurons appear to be more resistant than motor neurons. Proprioception, even decreased, proved to be capable of recovering even in old amputations [
Proprioception improvement after a long-term use of the prosthesis appears in the results of this study, as older patients with long-term placement of the prosthesis presented improved values in the measurements.
In the case of an above-knee amputation there is loss of the knee and of a significant number of mechanoreceptors that support the proprioceptive sensation of the lower limb [
The failure to detect proprioceptive deficits with the method used in this work, unlike other methods that measure kinesthesia, is probably shown due to the different neural mechanisms that are activated during the reproduction of the predetermined angle of 15° flexion used in the herein study [
The rehabilitation program followed after an amputation influences the final outcome of the proprioceptive sensation presented in the amputated lower limb. There are numerous physical therapy approaches focusing on different aspects of rehabilitation such as proprioceptive enhancement or restoration of muscle strength. In this study the participants did not follow the same rehabilitation program, a fact that can affect to some extent the results of this work.
Another weakness of the study is the heterogeneity of the sample as regards the age and the gender of the patients and the fact that the required measurements were performed in a hospital and not in a physical functional environment.
Further randomized trials are required for the exploration of the complex phenomenon of proprioception of the lower extremity after an amputation and placement of an artificial joint, with different methods that measure the different components of proprioception in an environment close, as possible, to normal gait.