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Effect of Combined Balance and Isotonic Resistive Exercises Versus Isotonic Resistive Exercise alone on Proprioception and Stabilizing Reactions of Quadriceps and Hamstrings and Functional Capacity of Knee Osteoarthritis Patients
ISSN: 2165-7025
Journal of Novel Physiotherapies
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Effect of Combined Balance and Isotonic Resistive Exercises Versus Isotonic Resistive Exercise alone on Proprioception and Stabilizing Reactions of Quadriceps and Hamstrings and Functional Capacity of Knee Osteoarthritis Patients

Naglaa Abdel Mohsen Mohamed Hussein*, Mowaffak Mustafa Abdul-Hamied Saad and Noha Abul-Haleim El Sawey
Physical Medicine, Rheumatology and Rehabilitation, Albert Einstein College of Medicine, Alexandria University, NY, USA
Corresponding Author : Hussein AN
Universitária St., 2069. Jd Universitário
Zip Code: 85819-110, Post-box: 711
Cascavel – Paraná – Brazil
Tel: 347 4792686
E-mail: [email protected]
Received: September 08, 2015; Accepted: September 21, 2015; Published: September 25, 2015
Citation: Mohamed Hussein NAM, Abdul-Hamied Saad MM, El Sawey NAH (2015) Effect of Combined Balance and Isotonic Resistive Exercises Versus Isotonic Resistive Exercise alone on Proprioception and Stabilizing Reactions of Quadriceps and Hamstrings and Functional Capacity of Knee Osteoarthritis Patients. J Nov Physiother 5:273. doi:10.4172/2165-7025.1000273
Copyright: © 2015 Mohamed Hussein NAM, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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Objectives: To compare the effect of combined balance and dynamic resistive exercise versus dynamic resistive exercise alone on proprioception and stabilizing actions of the quadriceps and hamstrings and functional capacities in patients with knee osteoarthritis.

Design: Randomized clinical trial.

Participants: Fifty nine patients with knee osteoarthritis randomized to group I (resistive exercise) (n=21) and group II (combined resistive +balance exercise) n=38.

Intervention: All patients had electrotherapy, flexibility and resistive exercises for the legs, 3 times weekly for 8 weeks. Group II also added balance exercises.

Main outcome measures: Knee examination, knee pain by visual analogue scale, Lequesne index, one repetition maximum for quadriceps, body mass index, recording of postural evoked surface EMG for quadriceps and hamstrings, and measurement of knee proprioception inaccuracy.

Results: Knee effusion improved in both groups with significantly higher improvement in group II (P=0.017). Knee pain significantly decreased in both groups with higher mean percent change in group II (-50.9 ± 29.59) than in group I (-41.2± 10.89) with no significant difference in between groups (P=0.48). Lequesne score significantly decreased in both groups without difference in between groups (P value within groups =0.000). One repetition maximum for quadriceps significantly increased in both groups with higher mean percent change in group II (50.43 ± 16.6) than in group I (47.02 ± 41.97) (P value within group =0.000, P in-between groups=0.64). There were limited significant changes of quadriceps and hamstring reflex EMG in both groups. There were significant improvements of knee joint proprioception inaccuracy at the three measured angles 10, 30, 60 in both groups. However the mean percentage of changes was higher in group II than in group I at the measured angle 10 and 30. Group I had significantly higher improvement at angle 60.

Conclusion: Balance exercises add to the benefits of resistive exercise to knee osteoarthritis patients.

Balance; Resistive; Exercise; Knee; Osteoarthritis
Knee osteoarthritis (OA) is the most common joint disability that produces significant pain, and is the second to most commonly affected joint after the interphalangeal joints of the hand [1,2]. Pain and joint stiffness are the primary presenting complaints in up to 50% of patients who demonstrate radiographic evidence of OA [3].
The goals of management of knee OA include restoring the patient’s diminished functional status and ameliorating pain. This is achieved through education about the disease process, proper joint protection and conservation techniques and exercise to improve static and dynamic muscle strength [1,4].
Numerous strengthening and flexibility exercises have been advocated for the treatment of knee OA. Quadriceps weakness have been commonly associated with knee OA. It was historically considered to result from disuse atrophy secondary to pain in the involved joint. However, quadriceps weakness is now considered a possible cause of osteoarthritis [1,5,6]. Quadriceps strengthening is a mandatory in any rehabilitation program for patients with knee osteoarthritis. It improves strength, function, and significantly reduce pain without exacerbating joint degeneration6.
In the contrary, Sharma et al. concluded [7] that greater quadriceps strength at baseline was associated with increased likelihood of tibiofemoral osteoarthritis progression in misaligned and lax knees. They suggested that subset –specific approaches beyond strengthening exercise should be developed to enhance joint –protective muscle activity [7].
Flexibility deficits also contribute to the functional impairments that arthritis patients experience at some point during the course of their disease [8]. Extension lag is a usual deformity noted about the knee. This adds to the preexisting varus or valgus malalignment. Stretching the quadriceps and hamstring muscles is crucial in the treatment of knee OA [8].
Impaired knee proprioception is well established in patients with knee osteoarthritis [9-13]. This proprioceptive impairment may contribute to knee OA or conversely may result from the pathologic changes of the disease and manifest clinically [13-15]. Propriocetive deficiency of the osteoarthritic knee has been quantitatively established by number of studies [15-17]. This proprioceptive deficit affects the muscle protective postural activities as demonstrated by abnormalities in postural evoked response of the quadriceps and hamstrings, including, increased amplitude of reflex activation of quadriceps and hamstrings, despite significantly reduced voluntary muscle power [18,19]. This paradox emphasizes the difference in the functional setup between reflex and voluntary activation.
In support of this view, it has been shown that improvement of voluntary muscular power of the quadriceps in patients with knee OA is not associated with any improvement of postural control parameters [20]. Consequently, postural reflex training may be more beneficial than strength training in such patients. Balance exercise recently has been added as a component of the rehabilitation program of patients with knee OA and has resulted in significant improvement in their functional capacities [21]. However, description of the effect of both balance and resistive exercise on the postural evoked response of hamstrings and quadriceps in patients with knee OA are lacking in the literature.
Therefore, in this study the authors sought to compare the effect of combined balance and dynamic resistive exercises versus dynamic resistive alone on proprioception and stabilizing actions of the quadriceps and hamstrings and functional capacity in patients with knee osteoarthritis.
Subjects and Methods
Study design
The study was a prospective randomized clinical trial. Ethics approval was obtained before initiation of the study from the research ethics committee at authors’ institution. All the testing procedures were carried out by an independent observer who was blinded to the two groups.
Fifty nine patients with knee osteoarthritis from those attending consecutively the outpatient clinic of physical medicine, rheumatology and rehabilitation department, Alexandria University (37 females, 22 males, age range 33-72y) volunteered for the current study. The entry criteria were: primary knee OA as diagnosed according to the American College of Rheumatology (ACR) criteria for classification of idiopathic knee OA22 with chronic or subacute presentations. Exclusion criteria were: secondary OA, any uncontrolled medical problems that precluded resistive exercise such as hypertension, angina, severe cardiomyopathy or diabetes, any other locomotor disorder or neurological disorders that precluded or interfered with the testing procedure accuracy.
Outcome measures
All patients signed an informed consent for participation in the study after being informed about the details of the procedures. At time of testing, patients were either having minimal or tolerable pain levels that did not interfere with testing prerequisites. All Patients had an initial medical history, occupational history, and drug history including use of any non steroidal anti-inflammatory agents, analgesic drugs, and drugs for chronic medical conditions. General examination and musculoskeletal examination were conducted for all patients. The latter included knee alignment, presence of any knee deformity, bilaterality of the disease, tenderness, and effusion. Patients filled out a visual analogue scale (VAS) for knee pain [23] and that represented the worse pain that the patient felt. Along with the Lequescne functional knee index for knee OA [24]. Assessment of one repetition maximum (1RM) for the quadriceps was performed for all patients [25]. The patients performed 3-4 times light weight carrying as warm up prior to 1RM [25].
Body weight and height were measured and body mass index (BMI) was calculated [25]. Body weight was done by regular scale in kilogram, height is measured in meters. Body mass index is calculated body mass / square height [25].
Recording of postural –evoked surface EMG (SEMG) activity of the quadriceps (rectus femoris) and the medial hamstring, bilaterally, were also performed in response to downward rotational perturbation of the support surface at angular velocity of 50 deg/sec, at a maximum amplitude of 8 degree while standing [26]. Also SEMG was recorded from gastrocnemius muscles. SEMG signals were picked up by surface disc electrodes where by the active, reference and the ground electrodes, all are mounted in a single special bar that was fixed by adhesive tape on the target muscle. The setting of SEMG was as follows: gain=290, input impedence=100,000 Mohm and band width was ranging between10Hz to 30 KHz (B&L Engineering, Tushin, CA). The picked up EMG signals were passed to a second stage amplifier, the band width of which was 10 Hz-500 Hz, with a typical gain of 2.6. Full –rectified and averaged SEMG signals were acquired using an 8-channel amplifier and the Equi-test software version 5.06. Sampling frequency was preset to 1 KHz. Patients were asked to keep standing balance without support throughout ten trials. All postural evoked EMG testing were done using the Equi-test apparatus, Neurocom International Inc. Oregon, USA [9]. The following data were extracted and analyzed from recorded traces: [9]
a- Onset latency of SEMG activity in milliseconds (ms).
b- Peak latency in (ms) of SEMG activity.
c- Peak amplitude of SEMG activity, normalized by dividing by the BMI [18].
d- Indices of muscle activation latency and amplitude symmetry of the right and left side thigh muscles: [9].
Right/left onset latency index=1- right quadriceps (rectus femoris) onset latency/ left quadriceps(rectus femoris) onset latency.
Right/left peak amplitude index=1- right quadriceps(rectus femoris) peak amplitude/left quadriceps(rectus femoris) peak amplitude.
The obtained number represents difference of the ratio from 1 which would be the result of the division if the right and left parameters were perfectly symmetrical. Similar equations were used for right/left peak latency index. The same calculations were made for the hamstring muscle as well.
e- Measure of deviation of quadriceps and hamstring from synchronous activation (Co-contraction Index) on each side; calculated as the difference of the quadriceps/hamstring latency ratio from 1:
Quadriceps /hamstring co-contraction index=1-quadriceps onset latency/hamstring onset latency.
f- Measure of activation strategy was used (strategy index); leg muscle activation first or thigh muscle activation first, calculated by dividing the onset latency of the hamstring muscle by that of the gastrocnemius. Values greater than 1 indicated earlier leg muscle activation, while values less than 1 indicated earlier thigh muscle activation. Strategy indices were calculated for both sides. The hamstring and gastrocnemius were chosen based on the notion that forward displacement of body center of gravity triggered by downward mechanical perturbation is corrected by sequential activation of those muscles [27].
Measurement of knee proprioception accuracy was done, by the ability of the subject to reproduce actively a flexion angle at which the knee had been previously placed actively while standing [28]. Separate measures were made from the knee as follow:
a-The patient was asked to stand comfortably, arms aside with exposed thighs and knees.
b- A goniometer was placed with the fulcrum aligned to the lateral end of the knee axis of flexion extension. Its arms were tape- fixed to the lateral aspect of the leg and thigh, in alignment with the long axis.
c- After explanation of the test to the subject, he/she was asked to flex the knee actively, while the foot was kept on the ground, to one of the knee predetermined angles 10, 30, 60 degrees. The observer controlled this procedure verbally by stopping the active flexion upon reaching the target angle shown by the goniometer.
d- The patient was allowed to consciously feel the achieved angle and then straighten up and then was asked to reproduce the target angle actively.
e- The procedure was repeated for the criterion angles; 10, 30 and 60 degrees.
f- The difference between the reproduced and the criterion angle in degrees was recorded.
g- The percentage of proprioception inaccuracy was calculated using the formula: target angle-achieved angle/ target angle × 100.
-At the beginning of the study, all patients attended a lecture about the nature of the disease and proper joint conservation techniques [29].
Those randomly included consecutive patients , then were assigned into two groups according to their national number, those with odd ending constituted group I (21patients) and those with even ending constituted group II (38patients). Both groups had the same flexibility and isotonic (dynamic) resistive exercise programs, physiotherapy, analgesic medications for 8 weeks
Exercise program
All patients in both groups performed the following exercise programs at our department for 3 sessions per week on alternate days, for 8 weeks.
1-Flexibilty exercise: Patients performed static stretching of both hamstrings and quadriceps muscles before the resistive exercise [30].
2- Isotonic (Dynamic) resistive exercise for quadriceps, using Cybex weight machine was conducted after electro-analgesia and flexibility exercises. Exercise was carried out at intensity of 40% of 1 RM for 8 repetitions [31,32]. The 1RM measurement was repeated every 2weeks so that the intensity of resistive exercise was kept at a constant level throughout the study. In addition, all patients were instructed to perform the same flexibility exercise at home on the remaining days of the week.
Group II performed; in addition, balance exercise in the form of retro-walking, walking on their toes, and balance board exercises, for whole of 10-15 minutes [21].
All patients received interferential current for both knees for analgesia. This was carried out before the exercise program, 10 minutes for each knee [33].
All patients were advised to use ice packs for 15 minutes for each knee at home, at the morning, on daily basis. This is as a modality for pain relief.
Analgesic medications
All patients were instructed to take acetaminophen, 500mg three times daily as needed in case of severe knee pain. In addition, patients were asked to stop the use of all other non steroidal anti-inflammatory drugs. This design so that we can determine whether a possible reduction in pain was the outcome of the proposed rehabilitation program and not due to pain medication.
Final evaluation
After 8 weeks all patients had the following measurements:
Local knee examination, visual analogue scale for pain, Lequescne index for severity of knee OA, 1RM assessment for quadriceps, Body mass index, recording of postural evoked SEMG activity and measurement of knee proprioception inaccuracy.
Statistical analysis
Results were expressed as mean and standard deviation as well as percent changes of the variables. Chi-Square or Fisher exact was used for non parametric data. Fisher exact was performed whenever prerequisites for chi square were not fulfilled. Paired t test was used to compare between variables within each group before and after the rehabilitation program. P was considered significant if ≤0.05. Mann Whitney U test was used to compare between variables in between the two groups at baseline and at the end of the study. P was considered significant if ≤ 0.05. This test was chosen for in-between group comparison since the measured values were not normally distributed. Pearson’s product moment correlation tests were done to correlate between clinical and laboratory variables. Significant correlation was considered if R was ≥0.4 and P was ≤ 0.05.
Clinical characteristics of the studied patients (Table 1)
The characteristics of both groups (age, gender, chronic diseases; namely diabetes mellitus, hypertension and coronary artery disease) were matched. The average age of patients in group I was 52.71 ± 10.5888 and in group II 56.26 ± 9.74 years. Group I included 15 females (71.4%) and 6 males (28.6%) while group II included 22 females (57.9%) and 16 males (42.1%). There was no significant difference between groups regarding co-morbid medical problems.
At baseline, all patients had bilateral knee involvement. With no significant difference in between groups as regard the presence of knee deformities.
After rehabilitation programs, effusion resolution was significantly higher in group II patients.
Changes of knee pain by VAS, functional capacities by Lequescne, changes of BMI and 1RM (Table 2)
Both rehabilitation programs resulted in significant improvement of knee pain as measured by the visual analogue scale and functional capacities of the patients as measured by Lequescne index. Group II patients who performed combined balance and resistive exercise showed higher mean percentage of improvement of both knee pain and functional capacities as compared with group I patients who performed resistive exercise alone.
At baseline, both groups were equivalent regarding BMI. After rehabilitation BMI did not change in either group.
After rehabilitation, 1RM significantly increased in both groups, without significant difference between groups. However the mean percent change was higher in group II after combined balance and resistive exercise.
Quadriceps (rectus femoris) and hamstrings (medial hamstring) surface EMG variables among the studied patients (Table 3)
Before the rehabilitation program, both groups showed no statistically significant difference regarding onset latencies of quadriceps and hamstrings. The peak latency of left quadriceps was significantly shorter in group I patients. After the rehabilitation program, group I patients performing resistive exercise had significant shortening of quadriceps and hamstring onset latencies, and a significant reduction of normalized quadriceps amplitude, with no change in peak latency of either quadriceps or hamstring. The changes in hamstring onset latency and quadriceps amplitude were significantly higher in group I patients.
The addition of balance training to the resistive exercise program in group II patients did not result in similar effect on onset latencies of quadriceps and hamstring and amplitude as resistive exercise alone did.
In addition, group II patients have led to significant prolongation of peak left hamstring latency.
Indices of symmetry, co-contraction and strategy of the quadriceps (rectus femoris) and medial hamstrings surface EMG among the studied patients (Table 4)
At the beginning of the study, despite randomization, group I had significantly longer quadriceps onset latency index that is, more asynchronous activation onset of the right and left muscles. At the end of the study, both rehabilitation programs in both groups did not change significantly the onset and peak quadriceps indices but the statistical relationship between groups had the same significance.
In addition, the hamstring onset latency index was significantly shortened only in group II patients after combined balance and resistive exercise.
At the beginning of the study, group I patients had significantly higher left quadriceps/hamstring co-contraction index. After the rehabilitation programs, group II patients who had performed combined balance and resistive exercise showed a significant increase in the co-contraction index. Group I patients who performed resistive exercise alone had a tendency to increase co-contraction index but the level was not significant
Knee joint proprioception inaccuracy in both groups (Table 5)
In the present study, both rehabilitation programs resulted in significant improvement of knee joint proprioceptive accuracy at the three measured angles 10, 30, 60. However the mean percentage of changes was higher in group II than in group I at the measured angle 10 and 30.
Group I had a significantly higher degree of improvement of proprioceptive accuracy at angle 60 than did group II
Correlation between clinical variables and quadriceps / Hamstrings surface EMG parameters at the end of the study for the studied patients (Table 6)
At the end of the study both groups had positive correlation between quadriceps onset latency and Lequescne score. Also group I patients had positive correlation between quadriceps peak latency and Lequescne score.
In group I, there was positive correlation between level of pain and quadriceps onset latency that is, the higher the pain level the more prolonged the quadriceps latency.
The better improvement of knee pain, functional capacities of the studied patients is attributable to the improvement of quadriceps strength. This is consistent with the well known positive effect of quadriceps strengthening for knee osteoarthritis patients [6,34,35]. The addition of balance training components to the resistive exercise can also explain the better level of improvement in group II patients. Addition of balance exercise to the quadriceps strengthening exercise in osteoarthritis patients have been shown to result in increase in the functional capacities of the patients and significant improvement of isokinetic muscle strength at higher angular velocities [21]. However, these authors did not measure voluntary muscle power by 1RM as in the present study.
It seems that the interaction between resistive exercise and balance exercise in the present study had some positive effects on the quadriceps strength.
Regarding the exercise protocol adopted in this study, it is assumed that employing static stretching prior to strength training was usually considered to enhance the performance and outcome of strength training [30]. On the contrary in a recent study, low volume of static stretching does not seem to have a significant effect on muscular endurance [36]. In another study, it is recommended that longer duration of static stretching to be avoided before performance requiring maximal strength [37]. However, the present study was carried out on patients with knee OA and did not use maximal strength.
More improvement of knee effusion in group II patients can be explained by better balance control that might have been the outcome of the added balance training.
Improvement of balance control is assumed to improve mechanical load adaptation by a joint structure. This controls the magnitude of mechanical load over the joint surface area, and prevents localized areas of over loading. The reduction of loading magnitude has been shown to have an influence on the gene expression of pro-inflammatory cytokines. Studies have shown significant reduction in COX2 gene expression by chondrocytes exposed to low magnitude mechanical loading [38]. This may explain the significant improvement of joint effusion in the group of patients who received balance training.
The prolonged EMG latency of the quadriceps and hamstring shown in previous studies among OA patients [9,39]. Implied that postural training could improve reflex parameters favoring shorter latencies. However, apart from prolongation of the peak hamstring latency, combined balance and resistive training did not change the reflex EMG response
There are no studies in the previous literature tested the effect of combined balance and resistive exercise on reflex EMG response of hamstring and quadriceps. The suggested balance program in this study might not be sufficient enough to modify reflex activation pattern of the quadriceps and hamstring in response to downward perturbation. It might be that the duration of the balance training during each session was not long enough (10 minutes), or the components of the employed balance program itself caused a lack of significant change in reflex EMG of the of the quadriceps and hamstring in this particular experimental setting i.e. downward perturbation. Also the interaction between balance and resistive exercise resulted in other reflex EMG changes rather than resistive exercise did alone.
Improvement of hamstring activation symmetry in group II patients could be attributed to favorable effect of balance training.
In the current study, resistive exercise alone and combined resistive and balance exercise were not able to improve the synchronization of contraction of quadriceps and hamstring. Both rehabilitation programs failed to modify muscle activation pattern i.e. agonist –antagonist activation in response to downward perturbation.
Previous studies have suggested that the observed tendency toward less synchrony of agonist antagonist activation in the knee OA patients might have its consequences on the efficiency of the mechanical stabilization of the joint. The tendency toward a wider gap of time of agonist antagonist activation might be related to the ongoing knee pathology with deleterious effects on both the mechanical and proprioceptive characteristic of the joint [40].
Improvement of proprioceptive accuracy in the studied patients after rehabilitation programs resulted from improved muscle strength. This is consistent with the previous literature, where improved muscle strength led to improved proprioceptive accuracy and functional abilities of patients with knee Osteoarthritis [41-43].
The higher degree of improvement of proprioceptive accuracy after addition of balance exercise to group II patients could be attributed to the better control of knee effusion in those patients. Chronic knee effusion has been shown to have a greater impact on proprioceptive inaccuracy [42]. Also balance exercise might have a positive effects on the central processing of proprioceptive information as well as the type and number of proprioceptive receptors involved in joint sense [42,43]. Studies have shown that proprioceptive deficit of the involved joint has been found to adversely affect the proprioception of the un-involved side, suggesting that central processing of proprioception information might be also reduced [11,43,44].
The higher degree of improvement of knee proprioceptive accuracy in both groups was not matched with the limited changes of reflex EMG parameters. This may be because the angle reproduction is conscious test but EMG is an automatic one. Also joint angle awareness may not be the only factor that controls the automatic response. Mechanical load receptors are not tested in the angle reproduction error.
Positive correlation between quadriceps onset latency and Lequesne score in both groups of patients proves the relation between postural control improvement and functional disease status.
Study limitation
The duration of the balance training during each session (10 minutes), or the components of the balance program might be the cause of lack of significant changes in the majority of the parameters of reflex EMG of the quadriceps and hamstring in response to downward perturbation after combined balance and resistive exercise. The duration of the study was 8 weeks; we do not know whether longer treatment duration would result in better responses.
Addition of balance training to resistive exercise give better improvement of the functional status, muscular strength and knee proprioceptive accuracy in patients with knee osteoarthritis. There is a need for future studies addressing better understanding of the relation between strength training and reflex postural control of the knee. Moreover, further research may consider different design of balance training in order to determine components that may help enhancing specific parameters of knee joint postural control in osteoarthritic patients.


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