Prophylactic Knee Braces Research Articles

Prophylactic Knee Bracing in Offensive Linemen of the National Football League: A Retrospective Analysis of Usage Trends, Player Performance, and Major Knee Injury.

Offensive linemen in American football are prone to high-energy valgus forces to the knee, leading to associated injuries. Some offensive linemen in the National Football League (NFL) wear prophylactic knee braces (PKB) to prevent ligamentous injury. This purpose of the study was to compare injury rates and performance between NFL offensive linemen who wear PKB and those who do not. It was hypothesized that brace wear would be associated with fewer major knee injuries and no difference in gameplay performance. Cohort study; Level of evidence, 3. For the 2014 through 2020 NFL seasons, offensive linemen with at least 200 game snaps per regular season were identified. Players were grouped by PKB status (bracers vs nonbracers) based on visualization of bilateral, dual-hinged metal knee braces as part of gameday uniforms on publicly available imaging databases and/or game videos. Major knee injuries, defined as those requiring the missing of games, were identified using publicly available data. Performance was assessed with Pro Football Focus grades for each season. Rates of major knee injury were compared between groups with the 2-sample Z test for proportions, and performance grades were compared with the unpaired t test. For the cumulative study period, bracers demonstrated a significantly lower rate of major knee injuries than nonbracers (0.013 vs 0.049 injuries per player, respectively; P = .04). Isolated MCL injury was the most common injury for nonbracers. There was no group difference in performance for the cumulative study period or during most individual seasons. Yearly prevalence of PKB usage declined steadily from 16.3% in 2014 to 5.6% in 2020. A subgroup analysis of rookie players demonstrated an overall downtrend in usage during the study period as well. Results indicated that knee brace prophylaxis by NFL offensive linemen was associated with a reduced risk of major knee injury without a significant difference in performance when compared with nonbracers. Despite this, the prevalence of PKB declined over the study period.

Efficacy of Prophylactic Knee Bracing in Sports.

Anterior cruciate ligament (ACL) and medial collateral ligament (MCL) injuries are common knee injuries, which can result from contact and noncontact during sports, recreation, or work-related activities. Prophylactic knee braces (PKBs) have been designed to protect the knee and decrease risk of recurrence of these injuries. Despite their success, PKBs have not been proven to be consistently effective and cost of the device must be evaluated to optimize its use in sports, particularly American football. Biomechanical studies have suggested that increased hip and knee flexion angles may reduce frontal plane loading with bracing which can protect the knee joint. This is essential with knee loading and rotational moments because they are associated with jumping, landing, and pivoting movements. The clinical efficacy of wearing PKBs can have an impact on athletic performance with respect to speed, power, motion, and agility, and these limitations are evident in athletes who are unaccustomed to wearing a PKB. Despite these concerns, use of PKBs increases in patients who have sustained an MCL injury or recovering from an ACL reconstruction surgery. As the evidence continues to evolve in sports medicine, there is limited definitive data to determine their beneficial or detrimental effects on overall injury risk of athletes, therefore leading those recommendations and decisions for their usage in the hands of the athletic trainers and team physicians' experience to determine the specific brace design, brand, fit, and situations for use.

Evaluation of the Preventive Effects of Knee Brace on Anterior Cruciate Ligament Injuries in Susceptible Individuals: a Systematic Review

Background: The results of various studies on the preventive effect of knee brace on anterior cruciate ligament (ACL) injuries in susceptible individuals are not summarized thus far, leading to doubts about their utilization for orthopedic specialists. The present study aimed at systematically reviewing the preventive effects of knee brace on ACL injuries in susceptible individuals.Methods: The present systematic review was performed on literature published since 2010 using the keywords of Prophylactic Knee Brace, Neoprene Knee Sleeve, Knee Brace, ACL, Tear Risk Factors, and Biomechanical Factors in databases of PubMed, Scopus, Springer, and ProQuest, as well as the Google Scholar search engine. The I2 index was used to assess heterogeneity among studies.Results: A total of 8 high-quality articles were enrolled in the present systematic review, all represented moderate heterogeneity (I2 index: 25%-75%). Of the enrolled studies, only one reported the ineffectiveness of knee brace in preventing ACL injuries, and the rest noticed the positive effect.Conclusion: The use of a prophylactic knee brace in individuals susceptible to ACL rupture can avoid sustaining pressure and possible damage to the knee and ACL. However, the results of the present study should be applied with caution.

Finite Element Analysis of a Novel Approach for Knee and Ankle Protection during Landing

There is a high risk of serious injury to the lower extremities during a human drop landing. Prophylactic knee and ankle braces are commonly used to reduce injury by restraining the motion of joints. However, braces that restrain joint range of motion (ROM) may have detrimental effects on the user’s kinematical performance and joint function. The present study aimed to propose a novel set of double-joint braces and to evaluate its protective performance in terms of the ankle and knee. Accordingly, the finite element method was performed to investigate the biomechanical responses of the ankle and knee in braced and unbraced conditions. The results showed that the semi-rigid support at the ankle joint can share the high impact force that would otherwise be inflicted on one’s lower extremity, thereby reducing the peak stress on the inferior articular surface of the tibia, menisci, and articular cartilages, as well as the horizontal force on the talus. Moreover, with knee bending, the elongated spring component at the knee joint can convert the impact kinetic energy into elastic potential energy of the spring; meanwhile, the retractive force generated by the spring also provides a more balanced interaction between the menisci and articular cartilages. This biomechanical analysis can accordingly provide inspiration for new approaches to place human lower extremities at lower risk during landings.

Effect of Prophylactic Knee Bracing on Anterior Cruciate Ligament Agonist and Antagonist Muscle Forces During Perturbed Walking.

Background:Anterior cruciate ligament (ACL) injuries most commonly occur after a perturbation. Prophylactic knee braces (PKBs) are off-the-shelf braces designed to prevent and reduce the severity of knee injuries during sports, yet their effectiveness has been debated.Purpose:To identify differences in ACL agonist and antagonist muscle forces, during braced and unbraced conditions, while walking with the application of unexpected perturbations.Study Design:Controlled laboratory study.Methods:A total of 20 recreational athletes were perturbed during walking at a speed of 1.1 m/s, and motion analysis data were used to create patient-specific musculoskeletal models. Static optimization was performed to calculate the lower-limb muscle forces. Statistical parametric mapping was used to compare muscle forces between the braced and unbraced conditions during the stance phase of the perturbed cycle.Results:The brace reduced muscle forces in the quadriceps (QUADS), gastrocnemius (GAS), and soleus (SOL) but not in the hamstrings. The peak QUADS muscle force was significantly lower with the brace versus without at 49% to 60% of the stance phase (28.9 ± 12.98 vs 14.8 ± 5.06 N/kg, respectively; P < .001) and again at 99% of the stance phase (1.7 ± 0.4 vs 3.6 ± 0.13 N/kg, respectively; P = .049). The SOL muscle force peak was significantly lower with the brace versus without at 25% of the stance phase (1.9 ± 1.7 vs 4.6 ± 3.4 N/kg, respectively; P = .031) and at 39% of the stance phase (1.9 ± 1.4 vs 5.3 ± 5.6 N/kg, respectively; P = .007). In the GAS, there were no significant differences between conditions throughout the whole stance phase except between 97% and 100%, where the braced condition portrayed a smaller peak force (0.23 ± 0.13 vs 1.4 ± 1.1 N/kg for unbraced condition; P = .024).Conclusion:These findings suggested that PKBs that restrict knee hyperextension and knee valgus/varus motion can alter neuromuscular patterns, which result in a reduction of QUADS force.Clinical Relevance:Understanding the way PKBs alter muscle function and knee mechanics can provide invaluable information that will help in making decisions about their use. Further studies should investigate different types of braces and perturbations to evaluate the effectiveness of PKBs.

A three-experiment examination of iliotibial band strain characteristics during different conditions using musculoskeletal simulation

Iliotibial band syndrome (ITBS) is a common chronic pathology mediated via excessive Iliotibial band (ITB) strain. The purpose using a three-experiment approach is to provide insight into the differences in strain between different athletic movements, the incidence of ITBS in females, the efficacy of different prophylactic modalities for ITBS and also the kinematic parameters associated with ITB strain. Experiment 1 examined male and female athletes performing run, 45° cut and one-legged hop movements, experiment 2 observed males and females, whilst running in five different orthotic conditions and experiment 3 examined males and females riding a cycle ergometer at 70, 80 and 90 RPM whilst in prophylactic knee brace and no-brace conditions. In each experiment, kinematics were obtained using a motion capture system and ITB strain was measured using a musculoskeletal simulation approach. In experiment 1, ITB strain was greater in the run (male = 3.87% and female = 4.37%; P < 0.001) and cut (male = 3.12% and female = 4.06%; P < 0.001) movements compared to hop (male = 0.87% and female = 1.54%). Experiment 2 showed that females exhibited increased ITB strain (male = 6.34% and female = 8.91%; P < 0.05) and ITB strain velocity (male = 57.17%/s and female = 77.41%/s; P < 0.05) and also in females that ITB strain velocity was greater (P ≤ 0.01) in lateral (80.22%/s) and no-orthotic (83.01%/s) conditions compared to medial (72.58%/s) and off the shelf orthoses (74.52%/s). The regression analyses across movements showed that ITB strain was predicted by sagittal and coronal plane mechanics at the hip (R2 = 0.15–0.30; P < 0.05) and sagittal, coronal and transverse plane kinematics at the knee joint (R2 = 0.15–0.22; P < 0.05). Further insight is provided into differences in ITB strain across functional athletic movements, the increased incidence of ITBS in females and the parameters linked most strongly with ITB strain during different movements is provided; whilst also highlighting the prophylactic efficacy of medial and off the shelf orthoses in female runners.

The Effects of Three Types of Prophylactic Knee Bracing on Abduction Angle and Abduction Moment of Knee Joint in Foot Rotation Positions during Single Leg Landing in Anterior Cruciate Ligament Injury

landing movements. The aim of the present study was to investigate the effect of three preventive knee joints on the variables of abduction angle and abduction moment in three types of single leg landing in healthy young people. Materials and Methods: 15 healthy young people participated in this research. These participants were asked to descend from a platform with height of 30 cm on a force plate in three directions of forward, inward, and outward. Data were recorded during synchronization of camera and force plate, and maximum abduction angle and abduction moment were calculated using MATLAB software. To test research hypotheses, repeated measures ANOVA with a significance level of more than 0.05 was used to evaluate the interactive effect of different types of knee-braces on different landing. Results: The interactive effect of different types of knee-braces on abduction (P = 0.416) and abduction moment (P = 0.442) did not depend on the type of landing. There was no significant difference between different knee braces in knee abduction (P = 0.759) and knee joint abduction moment (P = 0.657). There was significant difference between types of landing in knee abduction angle (P = 0.007) and abduction moment (P = 0.001). Conclusion : Regarding the findings of this research, it seems that between the two variables of landing and knee brace, the first one is more important, and athletes should avoid landing with external leg rotation as far as possible.

Hardness and Tensile Properties of Prophylactic Knee Brace Produced from Cow Bone and Periwinkle Shell Composites

Application of reinforced aluminium scrap for the production of prophylactic knee brace (Pkb) particularly with agro-waste materials is rarely available. In this work, hardness and tensile properties of aluminium alloy (Al 6063) straps reinforced with cow bone (Cb) and periwinkle shell (Ps) for the production of Pkb were investigated. The Cb and Ps sourced were cleaned and the Cb was sun-dried for 4 weeks before crushing with Denver laboratory Ball mill (Model: 48-D0500/Q). The Ps was also crushed, sun-dried for 7 days and treated in the oven (Model SDO/225) at 110 oC for 30 minutes to remove moisture. The particle size of 75 µm was used to cast six (6) each of aluminium/cowbone (Al/Cb) and aluminium/periwinkle shell (Al/Ps) composites. The cast aluminium composites of Pkb and original Pkb were investigated for density, hardness, and tensile properties. It was observed that addition of Cb and Ps in the cast Pkb gave a density of 2.68 g/cm3 and 2.60 g/cm3 respectively. The average values of hardness and tensile strength obtained were 41.18 BHN and 135.88 MPa respectively when Ps was added to the cast aluminium Pkb, while addition of Cb gave harness values of 40.45 BHN and tensile strength of 134.63 MPa.

Do neoprene sleeves and prophylactic knee braces affect neuromuscular control and cutting agility?

ObjectivesTo evaluate the effects of neoprene sleeves (NSs) and prophylactic knee braces (PKBs) on neuromuscular control and cutting agility. DesignMarkerless motion-capture technology tracked subjects (1) without a brace as a control (2) with NSs and (3) with PKBs during single-leg drop vertical jump (SLDVJ), single-leg squat (SLS), Y-excursion, and cutting movements. Movements were recorded five times per bracing condition in three different sessions. SettingUniversity laboratory. ParticipantsTen healthy, active subjects (5 male, 5 female; age range, 22–26 years). Main outcome measuresDegrees of motion and time to completion. ResultsUse of NSs and PKBs reduced subjects' hip internal rotation in the loading phase of SLDVJ (p = 0.026, 0.02) and SLS (p = 0.005, <0.001), reduced knee flexion in the loading phase of SLDVJ (p = 0.038, <0.001), and reduced knee frontal plane abduction (FPA) with SLS (p = 0.015, 0.024) and Y-excursion (p = 0.002, 0.005) compared to control. Use of PKBs decreased subjects’ hip internal rotation in the Y-excursion (p = 0.024) and reduced knee FPA in the SLDVJ loading phase (p = 0.014) compared to control. There was no difference in cutting agility for either group (p = 0.145, 0.347). ConclusionBoth NSs and PKBs positively impacted neuromuscular control without impacting cutting agility.

Effects of prophylactic knee bracing on knee joint kinetics and kinematics during single- and double-limb post-catch deceleration strategies in university netballers

The aim of the current investigation was to investigate the effects of a prophylactic knee brace on knee joint kinetics and kinematics during single- and double-limb deceleration tasks. Twenty female university first team-level netballers performed single- and double-limb deceleration tasks under two conditions (prophylactic knee brace/no-brace). Biomechanical data were captured using an eight-camera 3D motion capture system and a force platform. Participants also subjectively rated the comfort/stability properties of the brace, and their knee joint proprioception was examined with and without the knee brace using a weight-bearing joint position sense test. The results showed that during both single- and double-limb deceleration tasks, neither peak anterior cruciate ligament [brace: single = 1.30/double = 1.30 bodyweight (BW) and no-brace: single = 1.19/double = 1.29 BW] P = 0.51, patellofemoral (brace: single = 4.21/double = 4.93 BW and no-brace: single = 3.99/double = 4.63 BW) P = 0.20, nor patellar tendon (brace: single = 6.17/double = 6.49 BW and no-brace: single = 6.07/double = 6.14 BW) P = 0.49 kinetics were significantly affected as a function of wearing the knee brace. The findings also showed that the knee brace helped to increase participants’ perceived knee stability (P < 0.001), but there were no statistical improvements in weight-bearing knee proprioception (brace = 3.59 and no-brace = 2.94°) P = 0.44. The current investigation indicates that the utilization of prophylactic knee-bracing akin to the device used in the current study does not appear to reduce the biomechanical parameters linked to the aetiology of knee injuries during netball-specific deceleration movements.

Does the use of prophylactic knee braces prevent knee injuries in athletes?

Does the use of prophylactic knee braces prevent knee injuries in athletes?

Effects of a prophylactic knee bracing on patellofemoral loading during cycling

The aim of the current investigation was to utilize a musculoskeletal simulation approach to examine the effects of prophylactic knee bracing on patellofemoral joint loading during the pedal cycle. Twenty-four (12 male and 12 female) healthy recreational cyclists rode a stationary cycle ergometer at fixed cadences of 70, 80 and 90 RPM in two different conditions (brace and no-brace). Patellofemoral loading was explored using a musculoskeletal simulation approach and participants were also asked to subjectively rate their perceived stability and comfort whilst wearing the brace. The results showed that the integral of the patellofemoral joint stress was significantly lower in the brace condition (male: 70 RPM = 8.89, 80 RPM = 9.76, and 90 RPM = 12.30 KPa/kg s and female: 70 RPM = 11.59, 80 RPM = 13.07 and 90 RPM = 14.14 KPa/kg s) compared to no-brace (male: 70 RPM = 10.23, 80 RPM = 10.96 and 90 RPM = 13.20 and female: 70 RPM = 12.43, 80 RPM = 14.04 and 90 RPM = 15.45 KPa/kg s). In addition, it was also revealed that participants rated that the knee brace significantly improved perceived knee joint stability. The findings from the current investigation, therefore, indicate that prophylactic knee bracing may have the potential to attenuate the risk from the biomechanical parameters linked to the aetiology of patellofemoral pain in cyclists. Future, longitudinal analyses are required to confirm the efficacy of prophylactic knee braces for the attenuation of patellofemoral pain symptoms in cyclists.

Effects of prophylactic knee bracing on patellar tendon loading parameters during functional sports tasks in recreational athletes

This study investigated the effects of prophylactic knee bracing on patellar tendon loading parameters. Twenty recreational athletes (10 male and 10 female) from different athletic disciplines performed run, cut and single leg hop movements under two conditions (prophylactic knee brace/no-brace). Lower extremity kinetics and kinematics were examined using a piezoelectric force plate and three-dimensional motion capture system. Patellar tendon loading was explored using a mathematical modelling approach, which accounted for co-contraction of the knee flexors. Tendon loading parameters were examined using 2 (brace) × 3 (movement) × 2 (sex) mixed ANOVAs. Tendon instantaneous load rate was significantly reduced in female athletes in the run (brace 289.14 BW/s no-brace 370.06 BW/s) and cut (brace 353.17 BW/s/no-brace 422.01 BW/s) conditions whilst wearing the brace. Female athletes may be able to attenuate their risk from patellar tendinopathy during athletic movements, through utilization of knee bracing, although further prospective research into the prophylactic effects of knee bracing is required before this can be clinically substantiated.

Do Knee Braces Prevent Ski Knee Injuries?

Background: Alpine skiing has high rates of knee injuries. Prophylactic knee braces (PKBs) and functional knee braces (FKBs) are often prescribed by clinicians to reduce injuries or re-injuries in skiers. Objectives: This literature review evaluates current knowledge on the biomechanical and clinical effectiveness of prophylactic and functional knee braces in preventing knee injuries and their impact on the athletic performance of non-injured and injured individuals. Methods: A literature review was performed to analyze the efficiency of knee braces concerning the reduction of mechanical stress, influence on muscle control, performance and injury prevention. Results: Most of the available literature describes research on the use of knee braces in contact sports, specifically American football. In this context, several studies show braces to be more effective in preventing medial collateral ligament injuries than anterior cruciate ligament injuries in both cadaveric and clinical studies. The use of functional braces after anterior cruciate ligament reconstruction has been supported and refuted in both postoperative and long-term studies. Ski-specific studies show a positive effect of knee braces on proprioception; no influence on performance; and a protective effect on previously injured skiers. Conclusions: Current literature indicates PKBs may have a protective function in healthy patients, while influence on performance is minimal. Functional braces are recommended in ACL-deficient patients and are biomechanically effective under low-loading conditions. They may not be as effective in high-loading conditions, such as athletic activity. There is a protective effect of FKBs of preventing re-rupture of reconstructed ACLs and preventing further knee injuries on ACL-deficient knees in skiers. More research is needed to determine the effectiveness of PKBs snow sports.

Effects of a Prophylactic Knee Sleeve on Anterior Cruciate Ligament Loading During Sport-Specific Movements.

Prophylactic knee bracing is extensively utilized in athletic populations to reduce the high risk from knee injuries, but its role in the attenuation of anterior cruciate ligament (ACL) pathologies is not well understood. The aim of this investigation was to explore the effects of a prophylactic knee sleeve on ACL loading parameters linked to the etiology of injury in recreational athletes. Laboratory. Repeated measures. Thirteen healthy male recreational athletes. Participants performed run, cut, and single-leg hop movements under 2 conditions; prophylactic knee sleeve and no sleeve. Biomechanical data were captured using an 8-camera 3D motion capture system and a force platform. Peak ACL force, average ACL load rate, and instantaneous ACL load rate were quantified using a musculoskeletal modeling approach. The results showed that both average and instantaneous ACL load rates were significantly reduced when wearing the knee sleeve in the hop (sleeve = 612.45/1286.39N/kg/s and no sleeve = 743.91/1471.42N/kg/s) and cut (sleeve = 222.55/1058.02N/kg/s and no sleeve = 377.38/1183.01N/kg/s) movements. Given the biomechanical association between ACL loading and the etiology of ACL injuries, it is proposed that athletes may be able to attenuate their risk from injury during cut and hop movements through utilization of a prophylactic knee sleeve.

Effects of prophylactic ankle and knee braces on leg stiffness during hopping.

During human movement, the leg can be represented as a mechanical spring, with its stiffness potentially contributing to sports performance and injury prevention. Although many individuals perform athletic activities with joint stabilizers, little is known about the effects of prophylactic lower extremity braces on leg stiffness. The objective of this study was to investigate the effect of ankle and/or knee braces on leg stiffness measured during one-legged hopping at a range of frequencies. Thirteen male participants performed one-legged hopping with their dominant leg at frequencies of 2.2, 2.6, and 3.0 Hz. All participants were randomly tested under the following four brace conditions: 1) no brace (control), 2) prophylactic ankle brace, 3) prophylactic knee brace, and 4) prophylactic ankle and knee braces. Based on a spring–mass model, leg stiffness was calculated using data from an accelerometer. It was found that leg stiffness increased with increasing hopping frequency for each brace condition. However, there were no significant differences in leg stiffness among the four brace conditions at the three hopping frequencies. Since some level of leg stiffness is needed for optimal athletic performance and training, these results suggest that ankle and knee braces do not significantly interfere with dynamic hopping activities.

Prophylactic knee bracing alters lower-limb muscle forces during a double-leg drop landing

Anterior cruciate ligament (ACL) injury can be a painful, debilitating and costly consequence of participating in sporting activities. Prophylactic knee bracing aims to reduce the number and severity of ACL injury, which commonly occurs during landing maneuvers and is more prevalent in female athletes, but a consensus on the effectiveness of prophylactic knee braces has not been established. The lower-limb muscles are believed to play an important role in stabilizing the knee joint. The purpose of this study was to investigate the changes in lower-limb muscle function with prophylactic knee bracing in male and female athletes during landing. Fifteen recreational athletes performed double-leg drop landing tasks from 0.30m and 0.60m with and without a prophylactic knee brace. Motion analysis data were used to create subject-specific musculoskeletal models in OpenSim. Static optimization was performed to calculate the lower-limb muscle forces. A linear mixed model determined that the hamstrings and vasti muscles produced significantly greater flexion and extension torques, respectively, and greater peak muscle forces with bracing. No differences in the timings of peak muscle forces were observed. These findings suggest that prophylactic knee bracing may help to provide stability to the knee joint by increasing the active stiffness of the hamstrings and vasti muscles later in the landing phase rather than by altering the timing of muscle forces. Further studies are necessary to quantify whether prophylactic knee bracing can reduce the load placed on the ACL during intense dynamic movements.

Effects of prophylactic knee bracing on knee joint kinetics and kinematics during netball specific movements

ObjectiveTo investigate the effects of a prophylactic knee brace on knee joint kinetics and kinematics during netball specific movements. DesignRepeated measures. SettingLaboratory. ParticipantsTwenty university first team level female netball players. Outcome measurementsParticipants performed three movements, run, cut and vertical jump under two conditions (brace and no-brace). 3-D knee joint kinetics and kinematics were measured using an eight-camera motion analysis system. Knee joint kinetics and kinematics were examined using 2 × 3 repeated measures ANOVA whilst the subjective ratings of comfort and stability were investigated using chi-squared tests. ResultsThe results showed no differences (p > 0.05) in knee joint kinetics. However the internal/external rotation range of motion was significantly (p < 0.05) reduced when wearing the brace in all movements. The subjective ratings of stability revealed that netballers felt that the knee brace improved knee stability in all movements. ConclusionsFurther study is required to determine whether reductions in transverse plane knee range of motion serve to attenuate the risk from injury in netballers.

Effects of Prophylactic Knee Bracing on Lower Limb Kinematics, Kinetics, and Energetics During Double-Leg Drop Landing at 2 Heights

Background: Anterior cruciate ligament (ACL) injuries commonly occur during landing maneuvers. Prophylactic knee braces were introduced to reduce the risk of ACL injuries, but their effectiveness is debated. Hypotheses: We hypothesized that bracing would improve biomechanical factors previously related to the risk of ACL injuries, such as increased hip and knee flexion angles at initial contact and at peak vertical ground-reaction force (GRF), increased ankle plantar flexion angles at initial contact, decreased peak GRFs, and decreased peak knee extension moment. We also hypothesized that bracing would increase the negative power and work of the hip joint and would decrease the negative power and work of the knee and ankle joints. Study Design: Controlled laboratory study. Methods: Three-dimensional motion and force plate data were collected from 8 female and 7 male recreational athletes performing double-leg drop landings from 0.30 m and 0.60 m with and without a prophylactic knee brace. GRFs, joint angles, moments, power, and work were calculated for each athlete with and without a knee brace. Results: Prophylactic knee bracing increased the hip flexion angle at peak GRF by 5.56° (P < .001), knee flexion angle at peak GRF by 4.75° (P = .001), and peak hip extension moment by 0.44 N·m/kg (P < .001). Bracing also increased the peak hip negative power by 4.89 W/kg (P = .002) and hip negative work by 0.14 J/kg (P = .001) but did not result in significant differences in the energetics of the knee and ankle. No differences in peak GRFs and peak knee extension moment were observed with bracing. Conclusion: The application of a prophylactic knee brace resulted in improvements in important biomechanical factors associated with the risk of ACL injuries. Clinical Relevance: Prophylactic knee braces may help reduce the risk of noncontact knee injuries in recreational and professional athletes while playing sports. Further studies should investigate different types of prophylactic knee braces in conjunction with existing training interventions so that the sports medicine community can better assess the effectiveness of prophylactic knee bracing.

A-36 Free Communication/Poster - Bone, Bone Mineral Density, and Connective Tissue

A common intervention for knee pain is the use of a brace. Studies have focused on how knee braces affect the braced limb; but few have examined the effects on the contralateral limb. PURPOSE: This study will examine the bilateral electromyography (EMG) of lower limb muscles while wearing a unilateral wraparound, hinged, prophylactic knee brace during a drop landing task. METHODS: Eleven healthy females (age 21.6 ±1.6 years) performed five drop landings from a 30 cm box while wearing a knee brace on their dominant (right) leg - intervention condition (IC), and five landings with no brace- control condition (CC). EMG was recorded for bilateral Rectus Femoris (RF), Medial Hamstrings (MH) and Gluteus Medius (GM). The right leg was braced and the left leg was un-braced during the IC. Maximal Voluntary Contractions (MVC) were recorded for all muscles prior to testing and peak activity during the drop landing (%MVC) was recorded. Muscle activations were compared across conditions (IC vs. CC) and across leg (Right - Braced vs. Left - Unbraced). RESULTS: In the CC, the MH was activated to a higher level in the left than in the right limb (Table 1). There were no differences in all other comparisons (Table 1). CONCLUSION: A hinged prophylactic knee brace does not change EMG activity levels in the lower extremity muscles during a drop landing in healthy females. Prior research has shown that wearing a brace does change the joint biomechanics during landing in the braced and un-braced legs compared to a control condition. Changes in mechanical demand with no change in muscle activation could potentially increase the risk for injury when wearing a prophylactic knee brace as a preventative measure. Further study is needed on pathological populations that wear knee braces.Table 1: Peak muscle activations (% MVC) of lower extremity musculature during a drop landing.