Comparison of three knee braces in the treatment of medial knee osteoarthritis ´ Yoann Dessery, Etienne L. Belzile, Sylvie Turmel, Philippe Corbeil PII: DOI: Reference:
S0968-0160(14)00169-0 doi: 10.1016/j.knee.2014.07.024 THEKNE 1949
To appear in:
The Knee
Received date: Revised date: Accepted date:
28 February 2014 7 June 2014 21 July 2014
´ Please cite this article as: Dessery Yoann, Belzile Etienne L., Turmel Sylvie, Corbeil Philippe, Comparison of three knee braces in the treatment of medial knee osteoarthritis, The Knee (2014), doi: 10.1016/j.knee.2014.07.024
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ACCEPTED MANUSCRIPT Comparison of three knee braces in the treatment of medial knee osteoarthritis Yoann Dessery1,2, Étienne L. Belzile3,4, Sylvie Turmel3, Philippe Corbeil1,2
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Address for correspondence: Philippe Corbeil, PhD Pavillon de l’Éducation Physique et des Sports 2300, rue de la Terrasse Université Laval Québec, QC, Canada, G1V 0A6 Phone: 1 (418) 656-5604 E-mail:
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Institutions: 1 Département de Kinésiologie, Faculté de Médecine, Université Laval, Québec, QC, Canada 2 Centre de recherche FRSQ du CHA universitaire de Québec, Québec, QC, Canada 3 Division de Chirurgie Orthopédique, CHUQ, Québec, QC, Canada 4 Département de Chirurgie, Faculté de Médecine, Université Laval, Québec, QC, Canada
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Keywords: Knee brace; knee adduction moment; pain; valgus; external rotation
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ACCEPTED MANUSCRIPT Abstract Background: Conservative orthotic treatments rely on different mechanisms, such as three-
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point bending systems or hinges forcing external rotation of the leg and knee stabilization,
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to alter the biomechanics of the lower limbs and thus reduce knee loading on the affected compartment in patients with knee osteoarthritis (KOA). No previous study had compared
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the effects of these mechanisms on external loading and leg kinematics in patients with
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KOA.
Methods: Twenty-four patients with medial KOA (Kellgren-Lawrence grade II or III) wore
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three custom knee braces: a valgus brace with a three-point bending system (V3P-brace), an unloader brace with valgus and external rotation functions (VER-brace) and a functional
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knee brace used in ligament injuries (ACL-brace). Pain relief, comfort, kinematics and
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kinetics of the lower limbs during walking were compared with and without each knee
Results: Knee pain was alleviated with all three braces (p .16; Table 2 and Table 3). On the other hand, differences were found between the V3P and VER braces in the changes in knee joint kinematics (Figure 4). For knee adduction, a reduced value was observed with the V3P brace but not with the VER brace (–1.1° vs. 0.2°, respectively; p = .01). Concerning external
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ACCEPTED MANUSCRIPT rotation, a greater ankle external rotation was seen in the ACL and VER brace gaits than in the V3P brace gait (1.3° and 2.0° vs. –2.0°; p < .01 and p < .001, respectively). The VER brace
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also caused a greater change in external rotation of the knee than the V3P brace (1.7° vs. –
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0.3°; p = .02). In the V3P brace gait, the hip’s external rotation was greater than in the other
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brace gaits (2.4° vs. –1.3° and –3.2°; p = .03 and p < .001, respectively).
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ACCEPTED MANUSCRIPT 4. Discussion Our study aimed to compare the immediate effects on pain, comfort and medial knee
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loading of a custom-fitted unloader knee brace with valgus and external rotation functions, a functional knee brace used for ligament injuries and a valgus three-point bending system
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knee brace. Despite the lack of any statistically significant difference between braces in
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terms of knee loading and discomfort, we noted that two of the braces –the VER and ACL
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braces – allowed for a statistically significant decrease in knee joint loading during the terminal stance phase of gait. All three braces resulted in immediate pain relief.
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Pain is the major complaint made by patients suffering from KOA and is the principal cause of disability and loss of autonomy in seniors [2,5,6,27]. Consequently,
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recommendation guidelines for the management of KOA focus primarily on pain relief and
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functional improvement [3,7,28]. Our results showed that all the braces we tested
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alleviated pain but the two valgus braces seemed to be more effective (–35%; p < .01). The effectiveness of valgus knee braces with a three-point bending force mechanism in pain relief has been widely demonstrated, and our V3P brace result was similar to those found in previous studies of such braces [8-10,29]. The reduction in pain following the use of a brace with valgus and external rotation functions was also reported in a previous study [16], whereas, to our knowledge, the treatment of KOA with a brace intended for ligament injuries had never been tested. In spite of the effectiveness of valgus knee braces with a three-point bending force mechanism for pain relief, several recent studies have noticed that, when such braces are provided for the management of KOA, they tend to have low daily use (< 4 h/day) and poor compliance rates [7,14,29-31]. Patients’ disinclination to wear these knee braces for long periods is mainly due to the lack of noticeable benefits,
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ACCEPTED MANUSCRIPT poor fit and aesthetic aspects of the braces (bulkiness, weight, size) [31-33]. In this study, immediate discomfort did not differ significantly between braces. However, the discomfort
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level was reduced by 15 percentage points (i.e., 50%) with the VER brace (and 9 percentage
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points with the ACL brace) compared to the V3P brace. In a footwear study, comfort was assessed by the clinically minimal difference in rating on the VAS [10,11,34]. That study
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observed that the clinically minimal change in footwear comfort measured with the VAS
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was 9 percentage points. Extrapolating this data to ours could suggest that, even though no statistically significant difference was noticed, the observed difference could be clinically
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relevant. These reasons, plus the fact that the unloaded knee brace with valgus and external rotation is smaller, could favor better patient compliance with this brace. Thus, the results
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of this study concerning subjective pain and comfort levels suggest that the VER brace has the best potential among the three braces tested to improve the quality of life of patients
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with medial KOA.
Alleviation of knee pain is the major concern in medial KOA management. Several non-pharmacological treatments, such as valgus knee braces or lateral wedged insoles, aim to alter the biomechanics of the legs to decrease medial knee loading. Depending on the brands of knee braces, parameters and studies, valgus braces with a three-point bending force mechanism have been found to reduce KAM by about 10% [12-14]. This kind of brace works by reducing the knee adduction angle, which decreases the distance between the center of pressure and center of rotation of the knee joint and thus the lever arm between the center of rotation and the frontal ground reaction force vector [9,13,14]. Unlike previous studies, we did not find a significant reduction in medial knee loading with the V3P brace. This difference could be due to a smaller correction, with only a 1° reduction in
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ACCEPTED MANUSCRIPT the knee adduction angle during gait. The only study measuring the knee adduction angle correction during gait reported a 2.6° reduction for a significant (9.5%) decrease in the
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KAM [1,14,24,25,35]. The smaller correction in our study might be explained by the
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diagonal strap tension, which might not be tight enough, leading to a low pressure point on the knee. In addition, no valgus correction was incorporated into the V3P brace. Pollo et al.
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[9] showed that the amount of valgus correction incorporated into the brace was associated
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with the amount of unloading of the affected compartment and that increasing the strap tension did not have as great an effect as increasing the valgus angulation.
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The decrease in the knee adduction angle must apply pressure on the anatomic knee landmarks [2,9,33], which may cause discomfort for patients, usually proportionate to the
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deformity correction molded into the custom fit of the brace [12]. The VER brace avoids this contact pressure and uses a different mechanism: induced valgus (distraction between
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femur and tibia segments) and external rotation of the knee joint. Theoretically, distraction of the medial knee joint when the foot contacts the ground could reduce the force impact on the joint while external rotation allows for a more toe-out gait (increased foot progression angle [16]). A toe-out gait is known to induce a lateral shift in the center of pressure, reducing the knee lever arm [1,4,36-39]. As expected, a greater external rotation of the knee and decreased knee loading during the entire stance phase of gait were observed with the VER brace. The superior knee external rotation was supplemented by a larger ankle external rotation. However, contrary to our hypothesis and to the results of a previous study [16], the foot progression angle was not affected because of compensation at the hip joint level. So the decrease in knee joint loading with the VER knee brace could be due to the increased step width and the reduced frontal ground reaction force vector. However,
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ACCEPTED MANUSCRIPT although these two parameters are almost certainly involved, the results for the other two knee braces lead us to focus on the axial rotation of the three lower limb joints.
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In comparing all the braces, we find that the KAM peak during the late stance phase
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of gait, at push-off, is reduced with the ACL and VER braces, which amplify the external rotation of the foot and internal rotation of the hip more than the V3P brace. This external
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rotation of the foot progression angle could induce weight bearing on the medial side of the
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foot and thus decrease the KAM. As KOA progresses to varus malalignment, the femoropatellar joint is typically affected. Once the knee brace guides the leg into external rotation,
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the femoro-patellar joint may be better aligned and thus may contribute to the alleviation of knee pain. Furthermore, balance and proprioception are affected by this external rotation,
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which may in turn affect the subjective comfort of the brace. In spite of their effectiveness, valgus knee braces are not always prescribed due to
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patients’ poor compliance with the treatment over time. Indeed, longitudinal studies of these braces show that 42% of patients stop wearing them in the initial year – 64% of them in the first three months [33]. These withdrawals can be explained by a negative score for the advantage/drawback ratio [30,33], which seems to be influenced by brace comfort and size [36-38]. These drawbacks might lead to immediate negative feelings concerning the knee brace and its effectiveness. In the present study, 8 out of 21 participants (38%) reported greater discomfort with the V3P brace than the maximum discomfort score observed with the VER brace. Recent studies have considered improving the comfort of knee braces by adding pneumatic bladders or more adjustable parameters at the three pressure points, but without changing their intrinsic mechanisms [1,38,40,41]. Although
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ACCEPTED MANUSCRIPT their results are encouraging, past protocols were only carried out with finite-element analysis or a small number of patients (n < 10).
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Participants in our study did not wear standardized footwear and their shoes may
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have influenced the amplitude of the joint moments calculated. However, our study design compared participants within repeated conditions, so the statistical results should remain
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unchanged.
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Walter et al. [25] showed that reducing the peak KAM does not necessarily guarantee a corresponding decrease in peak medial compartment contact force and that a
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corresponding increase in peak knee flexion moment is the most likely explanation. In the study reported on here, there was no difference in peak absolute knee flexor moment
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between the knee braces tested (p > .96). In the absence of any change in peak absolute knee flexor moment, our results remain consistent with the idea that a reduced peak KAM is
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associated with a corresponding decrease in knee loading. Finally, a selection bias exists in studies relying on campus mailing, as only the most motivated individuals are likely to contact the study team. Thus, subjective reporting by patients may be rather optimistic and their feelings may be better than those of the population at large. One of the strengths of our study is the experimental design and crossover comparison of three different types of braces. This allowed us to better evaluate the relative importance of these mechanisms in explaining the functional benefits of the three knee braces. Although an increase in walking speed constitutes an important functional gain following the prolonged use of a knee brace, it adds a confounding variable that may mask
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ACCEPTED MANUSCRIPT the real effect of the brace [16]. For this reason, gait velocity was controlled during the different experimental sessions to isolate the effect of the brace.
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The functional knee brace used in ligament injuries also provided non-negligible
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benefits for patients with KOA. This brace, which affected leg kinematics very little during walking, had positive effects on knee loading, particularly with regard to the reduction in
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the second peak of KAM. Perceived pain relief and improved function among KOA patients
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could be due to enhanced joint stability [10]. Other mechanisms, such as improved proprioception and motor control, could also explain these results [42]. These causal agents
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were not quantified in this study. In light of the subtle differences between the various braces, the explanation related to joint stability represents a promising avenue.
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In conclusion, the three braces provide similar pain relief and improvement in function during gait in KOA patients. The VER knee brace with induced valgus and external
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rotation to the leg during knee extension offers a slight comfort advantage, particularly because of its smaller size, which could result in better compliance with treatment over the long term. However, the effects of this brace on daily wear and compliance over the medium term remain to be confirmed in future studies.
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ACCEPTED MANUSCRIPT Conflict of interest statement None of the authors have any employment, consultancies, stock ownership, honoraria, paid
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expert testimony, patent applications/registrations or received grants or other funding that
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are related to this study.
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Acknowledgments
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We gratefully acknowledge the editing work and suggestions by Zofia Laubitz. This study was supported by a scholarship program from FQRNT (Fonds de Recherche du
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Québec – Nature et Technologies), NSERC (Natural Sciences and Engineering Research Council of Canada) and Ergoresearch Inc. This research was also supported by the
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Fondation pour l’Avancement et la Recherche en Orthopédie du Québec (FAROQ) and an
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NSERC Discovery Grant to PC.
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ACCEPTED MANUSCRIPT Figure Captions Figure 1: Flow of participants through trial.
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Figure 2: Picture of the three knee braces. (A) ACL brace (ACL brace, Orthoconcept Inc., Laval, QC, Canada). (B) Valgus brace with three-point bending force mechanism (V3P brace,
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Orthoconcept Inc., Laval, QC, Canada). (C) Unloader brace with valgus and external rotation functions (VER brace, Orthoconcept Inc., Laval, QC, Canada). (D) Detailed description of the
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VER brace.
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Figure 3: External knee adduction moment during the stance phase of gait in the with and without (W/O) knee brace conditions for each of the three braces: ACL brace, V3P brace
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and VER brace.
Figure 4: Change in the mean knee adduction and ankle, knee and hip rotation angles during gait with the three knee braces. The ACL brace was the stabilization brace, the V3P
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brace was the three-point bending brace and the VER brace was the unloader brace with
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valgus and external rotation functions. A positive value for knee adduction angle means an increase in adduction. A positive value for ankle, knee and hip rotation means an increase in
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external rotation. Error bars correspond to the 95% confidence interval. add. = adduction; rot. = rotation. * = p < .05; ** = p < .01; *** = p < .001
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Figure 2
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Figure 3
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Figure 4
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ACCEPTED MANUSCRIPT Table 1: Description of biomechanical variables
Definition
First- and second-peak KAM
Maximum adduction moment of the knee during the first and last 50% of the stance phase, respectively
KAM angular impulse
Area under the knee adduction moment-time graph during the stance phase.
Gait velocity
First derivative of the middle of the ASIS-PSIS position on two consecutive strides at mid-distance on the walkway
Step length
Antero-posterior distance between right and left heel markers at heel strike
Step width
Medio-lateral distance between right and left heel markers at heel strike
Foot progression angle
Mean angle between the direction of progression and a reference line on the sole of the foot during the stance phase
Knee adduction angle
Mean angle of the shank segment relative to the thigh segment in the frontal plane during the stance phase
Ankle external rotation angle
Mean angle of the foot segment relative to the shank segment in the transverse plane during the stance phase
Knee external rotation angle
Mean angle of the shank segment relative to the thigh segment in the transverse plane during the stance phase
Hip external rotation angle
Mean angle of the thigh segment relative to the pelvis segment in the transverse plane during the stance phase
Frontal ground reaction forces
Frontal (sum of medio-lateral and vertical) ground reaction force at the first and second KAM peaks normalized according to body weight
Knee–center of pressure distance
Distance between the knee joint center and the center of pressure at the first and second KAM peaks
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Variable
KAM = knee adduction moment; ASIS-PSIS = anterior superior iliac spine and posterior superior iliac spine. Gait velocity was measured in m.s-1, step length and step width in cm, angles in °, ground reaction forces in N, external moment in Nm/Bw*Ht, angular moment impulse in Nm.s/Bw*Ht and lever arm and knee–center of pressure distance in mm.
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Table 2: Comparison of changes in subjective and spatio-temporal variables from baseline and between braces Between orthoses
Step length (cm)
Step width (cm)
Foot progression angle (°)
20.7
1.36
-0.01
(0.19)
(-0.02 — 0)
72.3
-0.7
(6.4)
(-1.5 — 0.1)
10.8
0.4
(2.3)
(0.2 — 0.7)
14.6
0.1
(3.9)
(-0.5 — 0.6)
.13
.05
.08
.11
< .01
.80
.18
.02
.54
25.3
-8.9
(-14.6 — -2.2)
1.39 (0.19)
< .01
29.9
-0.02
73.3
-1.0
(6.0)
(-1.9 — 0)
10.2
0.4
(2.6)
(0.2 — 0.7)
15.1
-0.2
(4.1)
(-0.6 — 0.3)
WO: Mean (SD)
.03
.09
.02
.17
< .01
.17
.68
.04
With: ∆ (95% CI)
24.1
-7.9
(17.1)
(-12.7 — -3.2)
-
(18.2 — 41.6)
(-0.03 — 0)
VER brace
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(17.0)
-
(12.6 — 28.7)
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With: ∆ (95% CI)
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< .01
WO: Mean (SD)
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Gait velocity (m.s-1)
-3.6 (-6.1 — -1.1)
ES
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Discomfort (%)
26.2 (22.4)
p
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Pain (points)
With: ∆(95% CI)
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Variables
WO: Mean (SD)
V3P brace
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ACL brace
p
< .01
ES
p
ES
.49
.41
.04
.22
.08
15.4 (5.8 —25.1)
1.37
0
(0.18)
(-0.2 — 0.1)
72.5
-0.3
(5.4)
(-1.1 — 0.3)
10.5
0.3
(2.8)
(0 — 0.7)
14.7
-0.2
(3.8)
(-0.6 — 0.1)
Power
.50
.03
.54
.03
.15
.27
.07
.33
.05
.24
.05
.12
.81
.01
.08
.20
.06
.57
.03
.14
With ∆ = values expressed as mean difference from baseline (95% confidence interval). WO = without brace; SD = standard deviation; ES = effect size. No difference was found between baseline values of the three braces (p > .05).
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ACCEPTED MANUSCRIPT
KAM impulse (Nm.s/Bw*Ht)
Knee–COP distance at 1st peak (mm)
Knee–COP distance at 2nd peak (mm)
Frontal GRF at 1st peak (%)
Frontal GRF at 2nd peak (%)
0.293 (0.118)
.06
.04
.22
-0.025 (-0.049 — 0.002)
13.8
-0.7
(5.0)
(-1.5 — 0.1)
29.9
-2.4
(20.1)
(-5.2 — 0.3)
.08
.09
28.5
-2.3
(17.9)
(-4.7 — 0.1)
107.9
-0.3
(11.2)
(-1.4 — 0.8)
103.8
-0.1
(7.2)
(-0.8 — 0.7)
0.340 (0.102)
.15
.13
.06
.13
.58
.03
.85
.01
With: ∆ (95% CI)
0.310
(0.117)
RI
.40
-0.006 (-0.019 — 0.008)
WO: Mean (SD)
p
ES
.20
.12
.24
.11
.52
.04
.23
.07
.06
.13
.60
.05
.12
.20
SC
ES
-0.011
(-0.028 — 0.006)
MA
(0.101)
p
PT ED
2nd peak KAM (Nm/Bw*Ht)
0.321
With: ∆ (95% CI)
CE
1st peak KAM (Nm/Bw*Ht)
WO: Mean (SD)
AC
Variables
V3P brace
NU
ACL brace
PT
Table 3: Comparison of changes in knee adduction moment and variables affecting it from baseline and between braces
-0.012
(-0.034 — 0.009)
14.5
-0.2
(4.8)
(-0.9 — 0.5)
32.3
-1.2
(19.3)
(-3.3 — 0.9)
30.8
-2.2
(17.6)
(-4.6 — 0.1)
108.0
-0.6
(11.5)
(-2.8 — 1.7)
104.1
-1.0
(5.7)
(-2.4 — 0.3)
VER brace WO: Mean (SD)
0.351 (0.113)
0.313 (0.122)
With: ∆ (95% CI)
Between orthoses
p
ES
p
ES
Power
.75
.02
.25
.07
.29
< .001
.28
.15
.09
.38
< .01
.16
.16
09
.38
.02
.13
.48
.04
.17
.02
.16
.90
.01
.07
.10
.13
.62
.02
.12
.05
.14
.30
.06
.26
0.002 (-0.013 — 0.017) -0.033 (-0.048 — 0.017)
14.8
-0.8
(5.4)
(-1.4 — -0.3)
32.4
-2.7
(20.9)
(-5.0 — -0.4)
31.1
-2.9
(18.2)
(-5.1 — -0.5)
110.5
-1.3
(9.9)
(-2.9 — 0.3)
104.8
-0.7
(5.1)
(-1.5 — 0.0)
With ∆ = values expressed as mean difference from baseline (95% confidence interval). WO = without brace; COP = center of pressure; GRF = ground reaction forces; KAM = knee adduction moment; SD = standard deviation; ES = effect size; Bw = body weight; Ht = height; No difference was found between the baseline values of the three braces (p > .05), except for the frontal GRF at 1st peak, where the VER brace value differed significantly from the other two conditions (p < .05).
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ACCEPTED MANUSCRIPT
AC CE P
TE
D
MA
NU
SC
RI
PT
Highlights - All three braces resulted in immediate pain relief. - No significant difference between braces in terms of knee loading and discomfort. - VER and ACL braces allowed a significant reduction in peak knee adduction moment. - VER knee brace with external rotation to the leg offers a slight comfort advantage.
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