The Effect of Early Progressive Resistive Exercise Therapy on Balance ...

Topics in Geriatric Rehabilitation • Volume 33, Number 4, 286-294 • Copyright © 2017 Wolters Kluwer Health, Inc. All rights reserved. DOI: 10.1097/TGR.0000000000000165

The Effect of Early Progressive Resistive Exercise Therapy on Balance Control of Patients With Total Knee Arthroplasty A Randomized Controlled Trial Razieh Yousefian Molla; Heydar Sadeghi, PhD; Amir Hossein Kahlaee, PhD

Background and Purpose: Although total knee arthroplasty (TKA) is a common treatment for severe osteoarthritis, high risks of fall and balance loss are the main complications of this procedure. While multiple rehabilitation protocols have been suggested for TKA, efficacy of early resistive exercise therapy aimed at improving balance has not yet been thoroughly investigated. Methods: In this double-blind randomized controlled trial study, 40 patients with severe osteoarthritis, sampled by a simple convenient method, were randomly assigned into either “control” group or “early resistive exercise” group. After TKA surgery, both groups attended a routine rehabilitation program while the experimental group received extra early resistive exercises. Static, semidynamic, and dynamic balance were assessed by the Sharpened Romberg (SRBT), Star Excursion (SEBT), and Berg (BBT) balance tests prior to surgery, after the rehabilitation process (seventh week), and at a 2-week later follow-up time (ninth week).

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nee osteoarthritis (OA) is a progressive degenerative disease and a leading cause of disability among the elderly.1,2 Prevalence of knee OA is higher in women and increases with age.1 Total knee arthroplasty (TKA) is a commonly accepted surgical procedure recommended for severe OA characterized by radiographic evidence of joint damage, moderate to severe persistent pain, and clinically significant functional limitations affecting the quality of life when conservative treatments such as

Author Affiliations: Department of Sport Biomechanics, Faculty of Physical Education and Sport Sciences, Islamic Azad University of Central Tehran Branch, Tehran, Iran (Ms Yousefian Molla and Dr Sadeghi); and Rofeideh Rehabilitation Hospital and Department of Physical Therapy, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran (Dr Kahlaee). This study was partly supported by Faculty of Physical Education and Sports Biomechanics, IAU. The authors have disclosed that they have no significant relationships with, or financial interest in, any commercial companies pertaining to this article. Correspondence: Amir Hossein Kahlaee, PhD, Department of Physical Therapy, University of Social Welfare and Rehabilitation Sciences, Koodakyar St, Daneshjoo Blvd, Evin, Tehran, Iran ([email protected]). 286

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Results: At the end of the seventh and ninth weeks, in both groups all 3 balance scores were significantly enhanced comparing the baseline scores (P < .001). The experimental group had significantly higher scores than the control group in SRBT, SEBT, and BBT after the intervention and at the follow-up time (P < .001). Discussion and Conclusions: The findings of this study showed that rehabilitation following TKA is accompanied by balance (static, semidynamic, and dynamic) improvement, and this improvement is greater among patients participating in an early resistive exercise regimen. Early progressive resistive exercise in addition to routine physical therapy may lead to better balance performance than routine physical therapy and might be incorporated into the postoperative physical therapy of these patients. Further studies with longer follow-up periods are needed to confirm these results. Key Words: balance, early resistive exercise, rehabilitation, total knee arthroplasty

nonsteroidal anti-inflammatory drugs, physical therapy, and intra-articular corticosteroid injections fail.1 Rehabilitation following TKA is crucial to the success of the surgery. Rehabilitation emphasizes exercise programs to improve range of motion, muscle flexibility, strength, endurance, and walking skills.3 Most studies recommend that rehabilitation be initiated immediately after discharge from the hospital.4 Falling is a serious problem with significant economic, personal, and social costs among the elderly with multiple risk factors.5 Balance loss has shown to be an important predictor of falls in this population6,7 and is, therefore, an important issue to be addressed after TKA to prevent falls and provide confidence to perform activities of daily living (ADLs) in a safe manner. Balance is also a crucial predictive factor for functional recovery after primary TKA. However, studies have reported diminished postural and neuromuscular control, as well as balance performance,8 and increased risk of falling following TKA compared with healthy age-matched individuals.9 Balance is the product of integration of multiple sensory inputs (visual, vestibular, and proprioceptive systems), central processing of these October–December 2017

Copyright © 2017 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited.

data, and neuromuscular responses, and is defined as the ability to maintain postural stability during quiet and perturbed standing and voluntary movement.10 Balance defined as the ability to maintain the center of mass within the body’s base of support11,12 can be assessed during static postures or dynamic tasks. The ability to keep the center of mass projection within base of support in a stationary state or within a moving context is referred to as static and dynamic balance, respectively.13,14 Altered proprioception will increase the risk of falls by adversely affecting the afferent information to the central-processing centers responsible for motor command generation.15 Deficient proprioception and reduced muscle strength have been commonly reported with the aging process, with the presence of knee OA and after TKA and are both shown to interfere with ADL performance and subsequently reduce quality of life.1 Reduced gait speed, difficulty in negotiating up and downstairs, balance loss, and risk of falling may persist as long-term complications of the TKA surgery in addition to postoperation muscular inhibition sequelae.16 Hence, physical therapy is necessary to mitigate the functional limitations following TKA. Since proprioception modulates muscular activity, affected knee joint mechanoreceptors may induce muscle weakness.17 Changes in the knee joint proprioceptor function may contribute to altered balance control during both static and dynamic tasks.18 Quadriceps (QC) muscle weakness after TKA is also attributed to failure of voluntary muscle activation (ie, muscle inhibition).19 One month after TKA, QC strength decreases to 60% of preoperative level.20 Lower extremity strengthening exercises can reduce functional limitations such as balance in the elderly.21 Based on the association of knee extensor muscles strength and dynamic stability in the elderly population, strengthening exercises of these muscles have been recommended for fall prevention during ADLs.22 Stensdotter et al23 found QC muscle strength to be correlated with the postural control capabilities of the subjects with TKA and thus recommended QC strengthening to be included in TKA postoperative rehabilitation. Lim et al24 have shown that strengthening the QC muscle after TKA via a progressive resistive regimen will enhance balance control. Early accelerated rehabilitation has received increasing attention in the last decade. Increased range of motion, muscle strength, functional performance, and quality of life have been the main outcomes of early rehabilitation after TKA.25 Although multiple studies have investigated different rehabilitation protocols after TKA, there are few comparing early progressive resistive exercises with more conventional protocols. Only 1 aspect of balance has been assessed as the outcome measure of most studies on TKA, but to our knowledge, no study has compared the effect of early resistive exercise therapy after TKA on the different aspects of balance.4,26,27 Topics in Geriatric Rehabilitation

The aims of this study were thus to investigate whether an early progressive strengthening exercise program could improve static, dynamic, and semidynamic balance compared with routine physical therapy in patients with TKA. We hypothesized that (i) a 6-week rehabilitation program after TKA would improve balance and (ii) addition of early progressive resistive exercise to routine physical therapy after TKA would yield greater improvement in balance.

METHODS Study design and randomization This investigation was a double-blind randomized controlled trial study examining the effect of early progressive resistive exercise therapy on balance in patients undergoing TKA. Participants were allocated to the experimental or control group in the order they were referred on a 1:1 ratio until there were 20 female subjects in each group. In this method, the first referred patient would fall into either group by chance and the next one into the other group. This would ensure avoidance of patient selection bias. The orthopedic surgeon referring the patients was unaware of allocation order. The patients were blinded as to what group they were assigned.

Setting and participants Forty female patients with severe primary knee OA (grade 4 on Kellgren/Lawrence classification system)28 were recruited into this study. All these patients, sampled by simple convenient method, were candidate for bilateral TKA surgery and were referred from the orthopedic clinic of Akhtar Hospital in Tehran during Spring to Fall 2013. Because of higher rate of OA among women, only females were included in this study.1 All subjects were informed about the content of the study and volunteered to participate by signing the informed consent form approved by the medical ethics committee of Shahid Beheshti University of Medical Sciences. The inclusion criteria were as follows: (1) age between 60 and 75 years, (2) primary knee OA, (3) both knees candidate for TKA, and (4) fixed prosthesis used for surgery. The subjects were excluded if they had a prior TKA surgery or any deformity in lower extremities other than in the knees or any neurological or noncorrected visual deficit affecting their balance. The sample size was calculated on the basis of the variance of the outcome measures and an extra amount to count for probable dropouts. Patients not attending 100% of their therapeutic sessions were also excluded from the study. The initial evaluation of all subjects, including demographic data, anthropometric characteristics, Sharpened Romberg (SRBT), Star Excursion (SEBT), and Berg (BBT) Balance Tests (to evaluate static, semidynamic, and dynamic balance, respectively),29-31 was performed 2 days prior to surgery. All patients underwent TKA surgery by www.topicsingeriatricrehabilitation.com


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the same surgeon and technique using a fixed articular surface prosthesis. While rehabilitation was started from the first day after surgery, the balance scores were remeasured after the rehabilitation process (7 weeks after surgery) and at a follow-up stage (9 weeks after surgery). All balance tests were scored by the first author who was unaware of the assignment of the subjects until the analysis phase of the study while the allocation sequence and assignment of the subjects were performed by the statistician who also performed the statistical analysis of the study.

Intervention The rehabilitation protocol (being the same for both groups until the second week postoperation) was initiated the day after surgery. The patients in both groups received 3 rehabilitation sessions a week for an hour per session and for 6 weeks (all patients were discharged from hospital within 3-4 days from the date of surgery). Routine rehabilitation included edema and pain control, regaining range of motion, improving knee flexor and extensor muscles strength performing isometric exercises of thigh muscles, ambulation, and gait training.32 Thus, both isometric and isotonic (nonresistive type) modes of exercise were included in the routine physical therapy program for knee flexor and extensor muscle groups. All patients received instruction regarding the appropriate use of assistive devices for ambulation. Continuous passive motion was started on the first postoperative day for the range of 0° to 60° being increased as tolerated.33 The rehabilitation program of the 2 groups became differentiated during the second week of the outpatient rehabilitation protocol. The control group performed both open kinetic chain (non– weight-bearing) and closed kinetic chain (weight-bearing) exercises initially with 2 sets of 10 repetitions, later progressed to 3 sets of 10 repetitions. Strengthening exercises consisted of QC isometric contractions, seated knee extensions (nonresistive), straight leg raises, side-lying hip abduction, and standing hamstring curls. Body weight exercises consisted of standing terminal knee extensions, single-limb stance, and wall slides. Since closed kinetic chain exercises targeting the knee joint muscles have been proposed to be crucial to balance control improvement after TKA,23,34 the experimental group received progressive, resistive exercises of knee extensor muscles in addition to the routine rehabilitation program. The isotonic resistive exercises were as follows: (1) stationary bicycling with minimum tension for 5 minutes with weekly increments in duration up to 30 minutes: resistance to the pedals was increased as tolerated by the patient; (2) getting up and down the stairs: the exercise would be initiated with stairs as high as 2 to 4 in and progressed to higher stairs (up to 6-8 in) with strength improvement during the rehabilitation phase of the study; and (3) weight-resisted knee 288


flexion and extension. Weights were increased to maintain a 10-repetition maximum targeted intensity level; the maximum weight utilized for any strengthening exercise was a 4.5-kg ankle weight. Duration of the cycling exercise, height of the stairs, and amount of weight resistance were gradually increased in a weekly manner and determined by the patients’ tolerance causing no persisting (lasting for more than 1 hour) pain and swelling.35 The lower extremity muscles (especially QC) have to overcome gravity force as large as whole body weight to accomplish the transfer phase of the stair-climbing task. Descending stairs also needs eccentric activation of the hip and knee extensor muscles to control body mass acceleration in the sagittal plane. Stairs ascent/descent exercise was thus considered as a strengthening exercise due to the aforementioned physical requirements. Stationary cycling also requires alternating hip and knee flexor and extensor muscles activation proportional to the resistance applied through the pedals. The rationale for external resistance adjustment was patient tolerance as recommended by the literature to avoid symptom exacerbation.31,33 The main difference of the administered rehabilitation protocols lies in the progressive and resistive nature of that in the experimental group. Both protocols included isotonic exercises but a more intense, progressive regimen was designed for the experimental group participants. Attendance of the participants to the rehabilitation program was tracked. Not completing the protocol would lead to the exclusion of the participant from the study. None of the participants were enrolled in any special physical activity other than usual ADL.

Outcome measures Participants’ static and dynamic balances were evaluated by SRBT, SEBT, and BBT within 1 week prior to surgery (preoperation) and at the end of the seventh (postoperation) and ninth weeks (follow-up) after the surgery for all patients. The tests performance order was randomized to minimize learning effect. In the SRBT, the patients were asked to hold the heel-to-toe standing position with the dominant foot behind the nondominant foot with open eyes. Time recording was started after the participant had assumed the proper position. The test would be stopped if the patient failed to hold the test position, or if she reached the maximum balance time set as 60 seconds.36 Three trials were performed. The longest balance time of the recorded trials was used for data analysis. The SEBT has been introduced as a simple, reliable, and cost-effective alternative for instrumental devices to assess semidynamic balance.35 The SEBT is a functional test that incorporates a single-leg stance on 1 leg while trying to reach as far as possible with the opposite leg. The patients stood in a square at the center of the grid with 8 lines extending from the center at 45° increments. The aim was to reach as far along each October–December 2017


direction as possible to touch the furthest point on the line while avoiding using the reach leg for support. The patients would then return to the center of the grid on both feet while maintaining balance.37 Each patient performed 3 reaches (trials) in each of the 8 directions. The average of the maximum reach distance in each of the 8 directions was considered for analysis. (A farther distance reached indicates better semidynamic postural control.) (Figure 1). The BBT assessment consists of 14 subtests evaluating balance during different sitting and standing postures and dynamic transfers between these postures. Each task was scored on a 5-point scale (0-4). The score “0” indicates the lowest and “4” the highest level of function. Maximum total score for this test is 56. Scores below 45 indicate that balance is limited, with an increased risk for falls.38 The reliability of the balance tests measurements using intraclass correlation coefficient statistical test was found to range between 0.73 and 0.94, indicating a high to very high level of reliability39 in the methodological phase of the study.

Statistical analyses Descriptive statistics (mean and standard deviation) were used to describe all study variables. The normality of the distribution of the data was tested by the KolmogorovSmirnov (K-S) test for all study variables before the main statistical analysis. Three separate time (3) × group (2) repeated measures analyses of variance were performed to determine the main and interactive effects for each dependent variable (SRBT, SEBT, and BBT). The withingroup factor was time (with 3 levels: pre- and postintervention and follow-up) and the between-group factor was intervention (with 2 levels: routine physical therapy vs

early resistive exercises in addition to routine physical therapy). Post hoc analyses with a Bonferroni correction were performed for pairwise comparisons. The student independent samples t test was used to analyze the differences between the SRBT, SEBT, and BBT in the 2 groups when the group main effect was found to be significant. Effect sizes (Cohen d) were calculated for the dependent variables at postintervention and follow-up times. The magnitude of the effect was classified as small (0.20-0.49), medium (0.50-0.79) or large (0.8) according to Cohen method.40 Statistical significance level was set at P < .05. Statistical analyses were performed using the Statistical Package for the Social Sciences (SPSS) software (version 20, SPSS Inc, Chicago, Illinois). Since there were no dropouts or missing data, all analyses were performed on all 40 participants (20 in each group).

RESULTS Participant characteristics Forty female patients with severe OA scheduled for primary TKA took part in this clinical trial. The analysis of the demographic characteristics revealed no significant difference between the 2 groups of patients (Table 1). The result of the K-S test was indicative of normal distribution of the data of the balance scores in both groups. No patients in either group experienced a musculoskeletal injury during the rehabilitation program. There was no surgery failure in either group according to the surgeon’s assessment at ninth week after surgery. Periprosthetic loosening, fracture, and infection are common surgery failures that need revision.41

Balance outcome Repeated measures analysis of variance test results showed that the interaction of the 2 independent variables (group × time) was statistically significant for SRBT (F = 75.68, P < .001), SEBT (F = 12.77, P = .001), and BBT (F = 10.42, P = .003) (Figure 2). The group (F = 18.77, P < .001) and time (F = 325.67, P < .001) variables had significant main effects on the scores of the SRBT. Post hoc analyses indicated that in both

TABLE 1 Comparison of the Demographic

Characteristics of the 2 Groups Experimental Mean (SD), n = 20

Control Mean (SD), n = 20

P

69.4 (5.7)

67.9 (5.3)

.322

BMI, kg/m

30.2 (5.2)

28.3 (5.3)

.216

Pain duration, y

5.6 (5.1)

5.2 (4.5)

.398

Group Variable Figure 1. Schematic representation of the SEBT test setup. The participants’ stance leg has been demonstrated in the center of the grid, while the reach leg tried to touch the furthest distance on each of the projecting lines. Topics in Geriatric Rehabilitation

Age, y 2



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Figure 2. Interactive plots of the (A) SRBT (seconds), (B) SEBT (cm), and (C) BBT score responses to the 2 intervention protocols at the preoperation, postoperation, and follow-up time intervals.

groups, SRBT scores were significantly increased from the preoperation to the postoperation and from postoperation to the follow-up time. The results revealed significant main effects for group (F = 12.07, P < .001) and time (F = 211.64, P < .001) variables on the SEBT scores. Just as the SRBT, the scores in SEBT test were significantly increased with progression of time in both groups. The main effects of the independent variables were also statistically significant in both groups on the BBT scores (F = 5.73, P = .285 for group and F = 132.76, P < .001 for time). Patients in both groups had higher balance scores after the interventions. The effect size (d) for outcome measures was greater for the experimental group at the seventh week after intervention in the SRBT (d = 2.2), SEBT (d = 1.3), and BBT (d = 1.9) than for the control group (d = 1.2, 0.9, and 1.5), respectively. The SRBT (d = 2.8) and BBT (d = 2.3) showed greater improvement in the experimental group after 2-week follow-up than those in the control group (d = 1.9 and 2.0), respectively. Results are presented in Table 2. The results also indicated that while the groups were statistically not different according to the balance scores at baseline, the experimental group had higher scores in SRBT (P < .001), SEBT (P < .001), and BBT (P = .002) after the 7 weeks of intervention and at the 9-week follow-up time (P < .001, .005, and .001, respectively) (Table 3). 290


DISCUSSION The main purpose of this study was to investigate the effect of addition of early progressive resistive exercises to routine physical therapy on balance performance of elderly women after TKA. The findings of this study showed that TKA surgery, followed by routine rehabilitation, with and without early resistive exercise regimen, is accompanied by static, semidynamic, and dynamic balance improvement. The findings are in line with those of recent studies investigating the effect of rehabilitation on balance in knee OA patients. Liao et al42 showed a positive effect of balance training in addition to functional rehabilitation, initiated within 2 months after hospital discharge, on balance, mobility, and function in patients with TKA. Silva et al43 in a systematic review reported that therapeutic exercise, especially QC strength training, would improve balance of women with knee OA. Since balance control incorporates both reliable sensory information and proper motor command necessitating adequate muscular force,11,44 improvement in either components (sensory and motor) may enhance balance performance. Deficits in knee joint proprioception and insufficient extensor muscles strength have been associated with knee OA and TKA and may both lead to balance loss.45,46 Closed kinetic chain exercises have been traditionally considered to enhance proprioceptive performance by stimulating the October–December 2017


TABLE 2 The Effects of Interventions on the 3 Balance Scores in Each of the Experimental

and Control Groups Group Experiment Test

Time Interval

SRBT, s

Pre-Post

SEBT, cm

BBT (score)

Control

Mean Difference (SD)

P

Mean Difference (SD)

P

18.6 (0.9)