The Effects of Functional Knee Brace on Postural Control in Patients Who Underwent Anterior Cruciate Ligament Reconstruction


Reza Salehi 1 , * , Shahin Goharpey 1 , Abdollah Tayebi 1 , Hossein Negahban 2 , Mohammad Jafar Shaterzadeh 1

1 Musculoskeletal Rehabilitation Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, IR Iran

2 Department of Physical Therapy, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, IR Iran

How to Cite: Salehi R, Goharpey S, Tayebi A, Negahban H, Shaterzadeh M J. The Effects of Functional Knee Brace on Postural Control in Patients Who Underwent Anterior Cruciate Ligament Reconstruction, Jentashapir J Cell Mol Biol. 2016 ; 7(5):e35435. doi: 10.17795/jjhr-35435.


Jentashapir Journal of Health Research: 7 (5); e35435
Published Online: September 21, 2016
Article Type: Research Article
Received: December 11, 2015
Revised: April 13, 2016
Accepted: May 27, 2016


Background: The current study aimed to evaluate the postural control in patients underwent anterior cruciate ligament reconstruction pre and post wearing functional knee brace.

Methods: Eighteen athletes undergone unilateral anterior cruciate ligament reconstruction included in the study. They had unilateral anterior cruciate ligament reconstruction at least six months before session test. Postural control was assessed pre and post wearing custom-fit functional knee brace using a posturographic platform prokin 254. The balance tests included: 1) standing on prokin platform with eyes open/closed on anterior cruciate ligament reconstruction limb, 2) standing on prokin platform with eyes open/closed on both limbs. The standard deviation (SD) of body sway along the anteroposterior (AP) and mediolateral (ML) axis, mean velocity of center of pressure (COP) along AP/ ML axis and the area ellipse (measured in 2 mm) were calculated.

Results: Results of the paired T-test revealed a significant effect on selected postural control variables for the brace conditions especially in low challengeable conditions (double leg, eyes open test situations) (P < 0.05). But in high challengeable conditions this effect was not significant.

Conclusions: Functional knee brace improved postural control in the simple balancing task in the subjects with anterior cruciate ligament reconstruction. But this improvement in more difficult balancing task was limited.

1. Background

Anterior cruciate ligament (ACL) sprain or tear is a common injury of knee ligaments (1). ACL injury often occurs during sports. Anterior cruciate ligament injury is common in high demand sports such as soccer, football and basketball (2). The primary role of ACL ligament is a mechanical restraint against anterior tibial translation (3). ACL deficiency reduces mechanical stability of knee (1). In addition to mechanical instability, ACL rupture inescapably displays reduced knee proprioception due to disruption of mechanoreceptors within the ligament (4). Disruption to both the sensory feedback and mechanical restraint role of the intact ACL following ACL rupture may result in impaired lower limb function and impaired postural control (5).

ACL-reconstruction can recover mechanical stability of knee but amendment of somatosensory function remains debatable (1). Literature suggests that in the first year after ACL-reconstruction, athletes may challenge with great risks of later injuries (3, 6).

Adding external stabilization of the knee by knee braces reduced likelihood of subsequent injury (7, 8). Although literature reported that compressive sleeves improve knee proprioception and single-limb standing balance in subjects with ACL-reconstruction, but research on the effects of knee brace on dynamic balance is limited (9, 10).

Although braces and sleeves may enhance proprioception acuity in non-weight bearing positions, generalization of this type of improvement to dynamic activities is questioned (11). Tasks that challenge the control of standing balance, by altering support surfaces and stance positions, are reported to provide predictable changes in performance and suggested to evaluate the postural control (5). Disturbance of dynamic postural control, between the two limbs of ACL-reconstructed group and between the ACL-reconstructed subjects and control group are reported (1, 5).

Assessing the postural control is frequently done by manipulation of size support area and perturbations of the base of support. Perturbation of supporting surface is a popular approach for the dynamic balance test. The dynamic postural tests showed considerably better accuracy than the static tests to predict injury during sport and functional activities (12). In the previous research less attention was paid to dynamic postural control tests and challenging tasks in the subjects who underwent ACL-reconstruction (5).

2. Objectives

The current study aimed to evaluate the effects a functional knee brace has on measures of dynamic postural control assessed using testing situations that including differing sensory inputs and limb support that challenged postural control to various degrees.

3. Methods

The participants of the study consisted of 18 athletes with a unilateral ACL injury who had ACL-reconstruction at least six months before testing, using semitendinosus-gracilis tendon graft. Non-probability sampling method was used to select subjects. Demographic characteristics of participants are shown in Table 1. The exclusion criteria for ACL-reconstructed subjects included any other orthopedic injuries (except meniscal injuries), neurological and strength deficits, range of motion restriction, pain and joint effusion at the time of testing (8-11). Subjects with ACL-reconstruction had been advised by their surgeons to resume previous physical activities. Participants had the Tegner score of 8.5.

Table 1. Demographic Characteristics of the Subjects With ACL-Reconstruction
VariablesMeanStandard Deviation
Males/femalesN: 16/2-
Age, y25.32.27
Height, cm1766.11
Weight, kg70.54.32
Time after surgery (months)7.10.9
Tegner activity level8.50.5

Abbreviation: ACL, anterior cruciate ligament.

For dynamic balance measurement pre and post wearing custom-fit functional knee brace, subjects with ACL-reconstruction were tested using a posturographic platform Prokin 254 (Pro-Kin Software Stability, TecnoBody, Italy), according to standardized methods. During the balance test, the participants were instructed to stand still on a force plate on both limbs and ACL-reconstruction limb with eyes open or closed.

In both legs test, the standing position was determined with their feet positioned comfortably within an area defined by dimensions equal to their foot length, keeping arms comfortably at their sides during the stances and look forward. In ACL-reconstructed leg test, subjects stood on the center of force platform. Balance tests were performed for 30 seconds and the mean of three trials was calculated for statistical analysis. Both and single leg in open or closed eyes condition tests was randomized.

The study was approved by the Ahvaz Jundishapur University of Medical Sciences ethics committee for health sciences research involving human subjects (code number: Eth-290, date: June 18, 2011). All subjects signed written informed consent before testing.

The standard deviation (SD) of body sway along the anteroposterior (AP) and mediolateral (ML) axis, mean velocity of center of velocity (COP) along AP and ML axis and the area ellipse (measured in 2 mm) were calculated.

For statistical analysis, statistical package for the social sciences (SPSS) version 19 (SPSS Inc., Chicago, IL, United States) was used. The normality of the distribution of all variables was assessed by the Shapiro-Wilk test. Descriptive statistics of continuous variables were reported as mean ± SD. Pre and post-test comparisons for continuous data were assessed with paired T-test. A P < 0.05 was considered statistically significant.

4. Results

Means and standard deviation for postural control variables during the ACL-reconstructed leg and double leg tests pre and post wearing knee brace are illustrated in Tables 1 and 2. Results of Shapiro-Wilk test showed that all data had normal distribution. Results of the paired T-test revealed a significant effect on the selected postural control variables for the brace conditions especially in low challenging conditions (double leg, open eyes test situation). Mean velocity, standard deviation of sway amplitude and sway area of COP in the bracing conditions decreased significantly (P < 0.05). However, there was no significant effect on the selected postural control variables of the brace condition in high challenging condition (single leg, closed eyes test situation) (P > 0.05). Only the standard deviation of sway amplitude in anterior-posterior direction in bracing condition showed a significant decrease (P value: 0.02).

Table 2. Postural Control Variables Pre and Post Wearing Knee Brace in ACL-Reconstructed Leg Stance
VariablesVisual ConditionPre-Test, Mean ± SDPost-Test, Mean ± SDP Value
SD sway amplitude, APOpen eyes5.22 ± 1.693.66 ± 0.760.02
Closed eyes10.22 ± 4.58.63 ± 0.980.27
SD sway amplitude, MLOpen eyes4.76 ± 1.783.11 ± 0.750.14
Closed eyes8.55 ± 3.166.88 ± 2.190.33
Mean velocity APOpen eyes16.1 ± 5.5813.83 ± 4.140.053
Closed eyes22.38 ± 3.8920.83 ± 1.130.49
Mean velocity, MLOpen eyes18.44 ± 6.9513.77 ± 4.90.082
Closed eyes40.33 ± 17.1928.53 ± 10.650.39
Ellipse area, mm2Open eyes233.73 ± 60.4184.10 ± 22.010.051
Closed eyes482.43 ± 167.12340.67 ± 132.860.31

Abbreviations: ACL, anterior cruciate ligament; SD, standard deviation; AP, anteroposterior; ML, mediolateral.

Table 3. Postural Control Variables Pre and Post Wearing Knee Brace in Double Leg Stance
VariablesVisual ConditionPre-Test, Mean ± SDPost-Test, Mean ± SDP Value
SD sway amplitude, APOpen eyes3.27 ± 0.572.43 ± 0.60.001
Closed eyes4.83 ± 1.043.55 ± 0.980.002
SD sway amplitude, MLOpen eyes2.83 ± 0.62.22 ± 0.540.004
Closed eyes4.72 ± 1.312.55 ± 0.610.001
Mean velocity, APOpen eyes10.04 ± 4.16.66 ± 1.090.001
Closed eyes15.5 ± 3.8912.8 ± 2.530.04
Mean velocity, MLOpen eyes10.88 ± 6.227.38 ± 2.420.017
Closed eyes16.55 ± 5.6411.09 ± 3.910.02
Ellipse area, mm2Open eyes95.83 ± 19.152.31 ± 12.10.005
Closed eyes128.23 ± 38.4106.1 ± 18.730.12

Abbreviations: SD, standard deviation; AP, anteroposterior; ML, mediolateral.

5. Discussion

An important finding of the study was the significant effects of functional knee brace on postural control in double leg stance in subjects with ACL-reconstruction, in contrast to the double-leg stance, single leg stance and closed eyes functional knee brace had no effect on the selected postural control parameter.

Patients with ACL deficit after ACL-reconstruction showed loss of proprioception acuity and there may be deficits in inter-joint coordination (13). Thus, disturbance in the dynamic stabilization of the knee joint with ACL-reconstructed is expected (5). Therefore, enhancement of stabilization of knee may restore proprioception acuity and balance control in subjects with ACL deficit (4, 7, 14). Biomechanical investigations showed that functional knee braces are able to restore knee stability. Giotis et al. (7) reported that braces decrease rotational knee instability under high-demand activities. Palm et al. (15) showed that elastic knee braces increase postural stability in patients with anterior cruciate ligament rupture but they reported no difference in the postural stability between uninjured and injured legs in the braced condition.

The brace affected amplitude of postural sway in the anteroposterior direction to control single leg standing balance, but had no significant effect in mediolateral postural sway. This finding was consistent with previous research. Birmingham et al. reported no effect of brace on mediolateral COP sway in subjects with ACL-reconstruction (9). Kuster et al. (10) found that wearing knee bandage had no significant effect on the one legged stance balance control mediolateral sway amplitude.

Although the brace improved balance control during the double leg standing balance, it did not affect the challenging balance conditions (single leg and closed eyes). A persistent increase of sway variables in difficult conditions indicated that subjects with ACL-reconstruction showed a significantly balancing deficit in ACL-reconstructed leg. Thus, the more challenging tests are recommended for balance control test in the subjects with ACL-reconstruction.

These findings were consistent with previous research by Birmingham that reported knee brace had no significant effect on balance control in challenging balance tasks (10). The more balance demanding tasks need considerable motor activity (16). Increased sensory motor activity demand in the more challenging balance tasks is not compensated with functional knee brace (9). Biomechanical studies reported that knee stability does not restore by wearing functional knee braces under high forces related to challenging activities (7). Beynnon et al. (17) showed that knee bracing was effective to reduce abnormal anteroposterior laxity in patients with chronic ACLtear in static conditions. However, they reported that braces were not effective in reducing the abnormal translations in dynamic conditions.

The current study had some limitations. First, postural situation tests consisted of nonfunctional tasks. Future researches are needed on the effect of knee bracing on postural stability in functional tasks. Second, all participants in the study were male; therefore results of present study can be generalized to male athletes. Moreover, further research should evaluate the long-term effects of knee brace on postural control.

5.1. Conclusion

ACL functional knee brace improves postural control in the simple balancing task in the subjects with ACL-reconstruction. But this improvement is limited in more difficult balancing tasks.



  • 1.

    Howells BE, Ardern CL, Webster KE. Is postural control restored following anterior cruciate ligament reconstruction? A systematic review. Knee Surg Sports Traumatol Arthrosc. 2011; 19(7) : 1168 -77 [DOI][PubMed]

  • 2.

    Munro A, Herrington L, Comfort P. Comparison of landing knee valgus angle between female basketball and football athletes: possible implications for anterior cruciate ligament and patellofemoral joint injury rates. Phys Ther Sport. 2012; 13(4) : 259 -64 [DOI][PubMed]

  • 3.

    Dargel J, Gotter M, Mader K, Pennig D, Koebke J, Schmidt-Wiethoff R. Biomechanics of the anterior cruciate ligament and implications for surgical reconstruction. Strategies Trauma Limb Reconstr. 2007; 2(1) : 1 -12 [DOI][PubMed]

  • 4.

    Friden T, Roberts D, Ageberg E, Walden M, Zatterstrom R. Review of knee proprioception and the relation to extremity function after an anterior cruciate ligament rupture. J Orthop Sports Phys Ther. 2001; 31(10) : 567 -76 [DOI][PubMed]

  • 5.

    Mohammadi F, Salavati M, Akhbari B, Mazaheri M, Khorrami M, Negahban H. Static and dynamic postural control in competitive athletes after anterior cruciate ligament reconstruction and controls. Knee Surg Sports Traumatol Arthrosc. 2012; 20(8) : 1603 -10 [DOI][PubMed]

  • 6.

    Kamath GV, Murphy T, Creighton RA, Viradia N, Taft TN, Spang JT. Anterior Cruciate Ligament Injury, Return to Play, and Reinjury in the Elite Collegiate Athlete: Analysis of an NCAA Division I Cohort. Am J Sports Med. 2014; 42(7) : 1638 -43 [DOI][PubMed]

  • 7.

    Giotis D, Zampeli F, Pappas E, Mitsionis G, Papadopoulos P, Georgoulis AD. Effects of knee bracing on tibial rotation during high loading activities in anterior cruciate ligament-reconstructed knees. Arthroscopy. 2013; 29(10) : 1644 -52 [DOI][PubMed]

  • 8.

    Moller E, Forssblad M, Hansson L, Wange P, Weidenhielm L. Bracing versus nonbracing in rehabilitation after anterior cruciate ligament reconstruction: a randomized prospective study with 2-year follow-up. Knee Surg Sports Traumatol Arthrosc. 2001; 9(2) : 102 -8 [DOI][PubMed]

  • 9.

    Birmingham TB, Kramer JF, Kirkley A, Inglis JT, Spaulding SJ, Vandervoort AA. Knee bracing after ACL reconstruction: effects on postural control and proprioception. Med Sci Sports Exerc. 2001; 33(8) : 1253 -8 [PubMed]

  • 10.

    Kuster MS, Grob K, Kuster M, Wood GA, Gachter A. The benefits of wearing a compression sleeve after ACL reconstruction. Med Sci Sports Exerc. 1999; 31(3) : 368 -71 [PubMed]

  • 11.

    Birmingham TB, Inglis JT, Kramer JF, Vandervoort AA. Effect of a neoprene sleeve on knee joint kinesthesis: influence of different testing procedures. Med Sci Sports Exerc. 2000; 32(2) : 304 -8 [PubMed]

  • 12.

    Pai YC, Maki BE, Iqbal K, McIlroy WE, Perry SD. Thresholds for step initiation induced by support-surface translation: a dynamic center-of-mass model provides much better prediction than a static model. J Biomech. 2000; 33(3) : 387 -92 [DOI]

  • 13.

    Kiefer AW, Ford KR, Paterno MV, Schmitt LC, Myer GD, Riley MA, et al. Inter-segmental postural coordination measures differentiate athletes with ACL reconstruction from uninjured athletes. Gait Posture. 2013; 37(2) : 149 -53 [DOI][PubMed]

  • 14.

    Solomonow M, Krogsgaard M. Sensorimotor control of knee stability. A review. Scand J Med Sci Sports. 2001; 11(2) : 64 -80 [PubMed]

  • 15.

    Palm HG, Brattinger F, Stegmueller B, Achatz G, Riesner HJ, Friemert B. Effects of knee bracing on postural control after anterior cruciate ligament rupture. Knee. 2012; 19(5) : 664 -71 [DOI][PubMed]

  • 16.

    Mouthon A, Ruffieux J, Walchli M, Keller M, Taube W. Task-dependent changes of corticospinal excitability during observation and motor imagery of balance tasks. Neuroscience. 2015; 303 : 535 -43 [DOI][PubMed]

  • 17.

    Beynnon BD, Fleming BC, Churchill DL, Brown D. The effect of anterior cruciate ligament deficiency and functional bracing on translation of the tibia relative to the femur during nonweightbearing and weightbearing. Am J Sports Med. 2003; 31(1) : 99 -105 [PubMed]

  • Copyright © 2016, Ahvaz Jundishapur University of Medical Sciences. This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License ( which permits copy and redistribute the material just in noncommercial usages, provided the original work is properly cited.