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Knee Braces: Current Evidence and Clinical Recommendations for Their Use

Knee Braces: Current Evidence and Clinical Recommendations for Their Use

SCOTT A. PALUSKA, M.D., and DOUGLAS B. MCKEAG, M.D., M.S. University of Pittsburgh Medical Center­Shadyside, Pittsburgh, Pennsylvania

Methods of preventing and treating knee injuries have changed with the rapid development and refinement of knee braces. Prophylactic knee braces are designed to protect uninjured knees from valgus stresses that could damage the medial collateral ligaments. However, no conclusive evidence supports their effectiveness, and they are not recommended for regular use. Functional knee braces are intended to stabilize knees during rotational and anteroposterior forces. They offer a useful adjunct to the treatment and rehabilitation of ligamentous knee injuries. Patellofemoral knee braces have been used to treat anterior knee disorders and offer moderate subjective improvement without significant disadvantages. Additional well-designed studies are needed to demonstrate objectively the benefits of all knee braces. Knee braces should be used in conjunction with a rehabilitation program that incorporates strength training, flexibility, activity modification and technique refinement. (Am Fam Physician 2000;61:411-8,423-4.)

Musculoskeletal injuries are commonplace in family practice patients, and many knee joint disorders are common among them. The knee is the largest joint in the body, and its exposed position makes it vulnerable to injury during athletic activities.1,2 While strength, flexibility and technique have historically been important components of knee injury management, the use of knee braces as preventive and therapeutic adjuncts has gained recent attention.3,4 The occurrence of knee injuries among high-profile athletes and the aggressive marketing of braces by manufacturers have also contributed to interest in the use of knee braces. As a result, patients may consult their family physicians for accurate, unbiased information about knee braces.

According to the American Academy of Orthopaedic Surgeons,5 knee braces fit into several categories: (1) prophylactic—braces intended to prevent or reduce the severity of knee injuries in contact sports; (2) functional—braces designed to provide stability for unstable knees; and (3) rehabilitative—braces designed to allow protected and controlled motion during the rehabilitation of injured knees. A fourth category includes patellofemoral braces, which are designed to improve patellar tracking and relieve anterior knee pain.

Knee braces may minimize knee injuries, but their true effectiveness remains debatable.1,2,6-9 The current situation is one of confusion among players, coaches, parents and physicians about when knee braces should be used, if at all. This article critically examines prophylactic, functional and patellofemoral knee braces and attempts to assist primary care physicians in selecting the appropriate brace for their active patients.

  • Prophylactic Knee Braces

After prophylactic knee braces were successfully tested in the National Football League, many athletes wanted access to similar products for use during contact activities. The prophylactic knee brace had been intended to protect the medial collateral ligament (MCL) during a valgus knee stress and to support the cruciate ligaments during a rotational stress.3 Their initial popularity has waned as increasing evidence has questioned their effectiveness, particularly considering the high cost of universal application.

Benefits and Limitations
Shortly after the introduction of prophylactic braces, several national studies attempted to determine whether they reliably prevent knee injuries. In general, inadequate control groups, subjective biases, variable rules of football, alternative treatment modalities for MCL injuries and inconsistent methods of data collection have limited comparison among most studies of prophylactic knee braces.10-12 Some researchers have concluded that prophylactic knee braces significantly reduce MCL injuries,11-13 while others have noted few beneficial effects with regular use.10
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Athletes who use knee braces often report more subjective benefits than can be objectively demonstrated.
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As with many types of athletic braces, reported subjective benefits often exceed objective findings. Brace wearers also have noted significant differences in joint position sense between braced and unbraced legs, but this noted difference has not been consistently confirmed.10

At best, prophylactic knee braces offer limited resistance to lateral knee impact and provide little meaningful rotational stress protection. At worst, they may generate increased forces that augment associated injuries to the medial knee.3,10 The benefits and limitations of prophylactic knee braces are summarized in Table 1.

Despite a lack of conclusive research, many players and coaches still consider using prophylactic knee braces. “Skill players” in football (receivers, kickers and running backs) have voiced the concern that prophylactic knee braces limit speed and agility, so they typically avoid routine brace wear. On the other hand, offensive and defensive linemen who are at greatest risk for injury wear prophylactic knee braces more frequently.11,12 Many players wear prophylactic knee braces in practices but not in games, because of feared performance limitations.
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TABLE 1
Knee Brace Classification and Summary
Brace type Indications Contraindications Reported benefits/evidence Risks/limitations
Prophylactic knee braces MCL protection against valgus knee stresses
Re-injury protection after previous MCL injury
Athletes at high risk for MCL injury To limit rotational control in ACL-deficient knees
Unstable knees requiring operative therapy Reduction of frequency and severity of MCL injuries following valgus knee stresses
Supporting cruciate ligaments during rotational stresses
Enhanced knee proprioception Injuries increased by excessivepreloading of MCL
Limited speed and athleticism
False sense of security for previously injured knee
Brace-related contact injuries to other players
Functional knee braces Reduce translation and rotation following ACL injury
Additional support after ACL surgery
Support for mild to moderate PCL or MCL instability Unstable knees requiring operative therapy
Complicated multi-directional knee injuries such as posterolateral corner injuries Laboratory evidence of reduced tibial rotation and knee AP translation
Subjective reports of decreased pain, enhanced performance, and improved confidence during athletics
Control of knee hyperextension
Augmented knee proprioception Reported effects on translation and rotation disappear at physiologic levels of use
Increased energy expenditure and decreased agility
False sense of confidence following ACL reconstruction
Brace-related contact injuries to other players
Patellofemoral knee braces Patellar subluxation and/or dislocation
Patellar tendonitis
Chondromalacia of the patella
Postsurgical effusion control Knee disorders unrelated to the patellofemoral joint
Knee translation or rotational control
Unstable knees requiring operative therapy Improved patellar tracking during knee flexion and extension
Dissipated lateral patellar forces
Decreased anterior knee pain syndromes
Subjective reports of decreased pain, enhanced performance and improved confidence during athletics Subjective benefits exceed objective findings
Increased skin irritation and lesions
Relatively insignificant pain relief with regular brace wear
Less effective than conservative therapy (simple stretching and strengthening)
MCL = medial collateral ligament; ACL = anterior cruciate ligament; PCL = posterior cruciate ligament; AP = anteroposterior.
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Obtaining and Fitting a Prophylactic Knee Brace
Currently, most prophylactic knee braces use unilateral or bilateral bars with hinges. Examples of both types are shown in Figure 1.
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Figure 1A Figure 1B Figure 1C
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FIGURE 1.Prophylactic knee braces: (A) with a unilateral-hinged bar, viewed from the side; (B) with a unilateral-hinged bar, viewed from the front; © with bilateral-hinged bars.
Parts A and C of Figure 1 reprinted with permission from dj Orthopedics.

In choosing a prophylactic knee brace, physicians should select the longest brace that fits the athlete’s leg, as shorter braces provide less MCL protection.3 Trying on several different braces before purchase may be helpful for determining the best fit. Cost is greater for custom braces than for off-the-shelf models; however, custom models provide few additional benefits. In addition, physicians may wish to contact several distributors or suppliers, as prices vary considerably. Details of various braces are given in Table 2. Brace efficacy depends on proper application. Regular tightening of straps, tape or hook-and-pile fasteners helps reduce unwanted brace migration. Also, shaving leg hair and fitting a brace closely to the contours of the leg may improve brace-skin contact and limit unwanted slippage. Correctly placing the hinge(s) relative to the femoral condyles is essential for optimal brace performance with minimal range of motion diminishment. Finally, prophylactic knee braces should be assessed daily by trainers and players for positioning and structural integrity. A broken or damaged prophylactic knee brace should be replaced to ensure maximum functionality.

  • Prophylactic Brace Summary
    The American Academy of Orthopaedic Surgeons and the American Academy of Pediatrics have concluded that prophylactic knee braces lack sufficient evidence of efficacy in reducing the incidence or severity of ligamentous knee injuries.1,5 A prophylactic knee brace may offer a subjective sense of protection, but it is unable to protect an MCL during a direct lateral impact. Researchers have found that prophylactic brace usage is less important in MCL injury prevention than strength training, conditioning, technique refinement and flexibility.10 Additional well-designed studies are needed to identify the proper role for prophylactic braces. Currently, the regular use of a prophylactic knee brace at any level of athletic competition is not recommended.
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    The American Academy of Orthopaedic Surgeons and the American Academy of Pediatrics have concluded that prophylactic knee braces lack evidence of efficacy in reducing knee injuries.
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  • Functional Knee Braces

Functional knee braces gained popularity among football players after Joe Namath used one in his successful comeback after a knee injury.14,15 The braces are designed to reduce knee instability following injury to the anterior cruciate ligament (ACL) and to decrease additional injuries during athletic activities.4,5,7 They were initially marketed for use by athletes with knee joint instability who participated in activities that required rapid direction changes.8 More recently, functional knee braces have been recommended following reconstructive surgery to reduce strain in an ACL graft.8,16

Benefits and Limitations
Few standardized, controlled studies have assessed the clinical efficacy of functional knee braces.2,7,14 Brace manufacturers cite laboratory tests using cadavers or surrogate leg models that demonstrated limitations of tibial rotation and anteroposterior translation, but these effects rapidly diminished during physiologic stress loads.2,4,8,10,16,17 Nonetheless, many persons who use functional knee braces report subjective improvements that exceed objective measurements of knee stability, pain attenuation, performance enhancement and confidence during athletics.4,7,17

Some researchers found that energy expenditure increased with functional knee brace use during lengthy athletic endeavors, but others reported no adverse performance effects.3,14,16,17 The regional muscle ischemia and lactic acid build-up observed with brace use may precipitate an increase in muscle fatigue.4,17 Researchers have also concluded that functional braces provide few proprioceptive effects and may expose athletes to additional risk by imparting a false sense of confidence.4,8,14,17 Strengths and weaknesses of functional knee braces are outlined in Table 1.
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Figure 2A Figure 2B Figure 2C
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FIGURE 2.“Hinge-post-shell” functional knee braces are designed to reduce knee instability following injury.
Reprinted with permission from dj Orthopedics (part A), Innovation Sports (part B) and Bledsoe Brace Systems (part C).

Obtaining and Fitting a Functional Knee Brace
Functional knee braces are available in custom or presized models. Both categories use a “hinge-post-shell” or a “hinge-post-strap” design, which differ in their thigh and calf enclosures. The former uses a molded shell of plastic and foam, while the latter uses a system of straps around the thigh and calf.3 Some studies have suggested that hinge-post-shell designs provide improved tibial-displacement control, greater rigidity, enhanced durability and better soft tissue contact.2,14,16 Examples of functional knee braces are shown in Figure 2.

Custom braces require several measurements of the affected leg to be taken to produce a brace that closely conforms to the desired size. Presized braces are sized by measuring the thigh circumference 6 in above the mid-patella and selecting the corresponding brace size. Presized braces may be desirable for use in patients who have changing limb girths during rehabilitation. In contrast, custom functional knee braces are more appropriate for abnormal limb contours and high-level athletes, or for enhanced patient comfort.2

Because studies comparing prefabricated and custom braces have found few significant clinical differences, presized braces may be better when cost or rapid availability is important.8,17 Costs vary considerably, so several suppliers should be contacted before a brace is purchased. Details of various functional knee braces are given in Table 2.

Accurate sizing will limit brace migration and improve brace effectiveness. Most companies make braces of different lengths, and the longest length the athlete can comfortably wear should be chosen. Setting 10 to 20 degrees of extension limitation may help minimize hyperextension of the knee joint.2 Attention to correct hinge placement relative to the femoral condyles improves the overall brace performance and efficacy.8 Finally, any exposed metal should be covered to limit brace-induced injuries to others, and more durable materials should be chosen for contact sports.
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TABLE 2
Knee Braces—Manufacturers and Product Information
Manufacturer/telephone number Knee brace type Name of product Additional information Cost*
dj Orthopedics
800-336-6569 Prophylactic DonJoy Protective Knee Guard Unilateral support $ 44
Prophylactic DonJoy Playmaker Bilateral support 125
Functional DonJoy Legend Presized fit 325
Functional DonJoy Defiance Custom fit 525
Patellofemoral DonJoy On-Track — 79
Omni Scientific
800-875-9080 Prophylactic Anderson Knee Stabilizer 1 Unilateral support 110
Prophylactic Anderson Knee Stabilizer 2 Bilateral support 120
Functional Omni Scientific Spectrum Presized fit 375
Functional Omni Scientific Avant Guard Custom fit 550
Patellofemoral Omni Scientific Sport Sleeve — 40
McDavid Knee Guard, Inc.
800-237-8254 Prophylactic McDavid Protective Knee Guard Unilateral support 45 to 60
Prophylactic McDavid Pro Stabilizer Bilateral support 48 to 60
Bledsoe Brace Systems
800-527-3666 Functional Bledsoe Ultimate CI Presized fit 325
Patellofemoral Bledsoe Sport Max — 55 to 89
DePuy Ortho Tech
800-227-1554 Functional Ortho Tech Ultimate Controller Presized fit 280
Functional Ortho Tech Montana Custom fit 700
Patellofemoral Ortho Tech Neopatellar Stabilizer — 36
Seattle Orthopedic Group
800-248-6463 Functional Lenox Hill Precision Fit Presized fit 339
Functional Lenox Hill Spectra Light Custom fit 440
Townsend Design
800-432-3466 Functional Rebel Series Presized fit 500 to 800
Functional Air Series Custom fit 750 to 1250
Patellofemoral Neoprene Sport Brace — 58 to 99
Palumbo Orthopedic
800-292-7223 Patellofemoral Palumbo Patella Stabilizing Brace — 39
Ortho-Care
800-821-1303 Patellofemoral Ortho-Care Body Flex — 34
Pro Orthopedic Devices, Inc.
800-523-5611 Patellofemoral Dr. “180-U” Universal Patellar Brace — 35
*—Prices are approximate costs furnished by the manufacturers. Actual cost to consumer may be higher.
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  • Functional Brace Summary
    Functional knee braces deserve consideration as a component of the treatment and rehabilitation for ligamentous knee instability. They offer some control of external knee rotation and anteroposterior joint translation.17 Functional knee braces are also useful adjuncts to muscular rehabilitation for graft protection following ACL reconstruction.7 Although brace wearers consistently report subjectively improved knee stability and function, the objective effects of functional knee braces appear to diminish at physiologic stress levels.4,8
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    Figure 3A Figure 3B
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    FIGURE 3.Patellofemoral knee braces are intended to resist lateral displacement of the patella and thereby decrease knee pain.
    Reprinted with permission from dj Orthopedics.

While functional knee braces have not been shown to be harmful, their correct application depends on appropriate rehabilitation and activity modification. Overall, lower extremity muscle strengthening, flexibility improvements and technique refinement are more important than functional bracing in treating ligamentous knee injuries.

  • Patellofemoral Braces

Anterior knee pain is a common disorder among active persons of all ages. Although definitions vary, the painful anterior knee syndrome is most often thought to originate from a malalignment of the patellofemoral joint.9,18-20 Patellofemoral braces were introduced to resist lateral displacement of the patella, maintain patellar alignment and, theoretically, decrease knee pain.3,15 Low cost, ease of use and availability promoted their widespread use. Nevertheless, many efficacy claims made by brace companies are not based on objective evidence.6,21

Benefits and Limitations
General agreement exists regarding the utility of conservative therapy in the initial management of anterior knee pain.9,22 Less clear is the role of bracing as part of the therapeutic regimen. Several studies have demonstrated significant improvements in patellofemoral pain symptoms with the use of patellofemoral knee braces,18,19,21,23 but others have found them to be ineffective.6,24

This lack of consensus stems from the absence of well-controlled studies addressing their efficacy. Nonetheless, patients appear to welcome patellofemoral braces and report significant subjective improvements in pain and disability with brace wear.18,21,23,25 A compilation of reported benefits and limitations of patellofemoral braces is outlined in Table 1.
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TABLE 3
Fitting a Patellofemoral Knee Brace

Obtain circumference of affected leg(s) according to the selected manufacturer’s specific guidelines by measuring: 3 in above and 3 in below mid-patella or Around center of knee joint with leg relaxed and extended.
Select the corresponding brace size (XS to XXL).
Pull brace onto affected leg(s). Most can be worn interchangeably on either knee.
After determining desired medial or lateral placement, position buttress support(s) comfortably if adjustable.
Align patella in center of cutout if applicable.
Secure counterbalancing strap(s) if present with moderate tension. Remove excess strap material as needed.
Periodically inspect brace for migration, strap loosening or material fatigue.

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Obtaining and Fitting a Patellofemoral Brace
Many different patellofemoral knee braces are currently available, and some examples are shown in Figure 3. They usually incorporate an elastic material such as neoprene and may include straps or buttresses that help to stabilize the patella. For most persons, an off-the-shelf version can be successfully fitted and used without the need for customization.3 A more active person may prefer a patellofemoral brace with a lateral hinge and adjustable patellar buttress. Details of various braces are given in Table 2.

Brace effectiveness depends on correct application and use, and steps for accurately fitting patellofemoral braces are listed in Table 3. Counterbalancing straps are usually secured superiorly but may be placed inferiorally for infrapatellar tendonitis. Buttresses are typically placed laterally, but medial placement may diminish medial patellar subluxation. Shoe orthotics should be considered in addition to a brace for patients with recalcitrant patellofemoral pain syndrome.22
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Studies have yet to prove or disprove unequivocally the benefit of patellofemoral knee braces in the treatment of anterior knee pain syndromes.
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  • Patellofemoral Brace Summary
    Patellofemoral braces are an inexpensive, subjectively helpful component of anterior knee pain therapy. Their mechanism of action remains unclear, but most appear to improve patellar tracking through a medially directed force.25 Changes in regional temperature, neurosensory feedback or circulation may also contribute to their effects.23 Overall, patellofemoral braces should be used in conjunction with a comprehensive knee rehabilitation program that includes strengthening, flexibility and technique improvements.
The authors thank Nancy McElwain, Ph.D., for support in the preparation of the manuscript.

The Authors

SCOTT A. PALUSKA, M.D.,
is currently in private practice in Cary, N.C. Dr. Paluska graduated from the University of Michigan School of Medicine in Ann Arbor, where he also completed a residency in family medicine. He completed a fellowship in primary care sports medicine at the University of Pittsburgh (Pa.) Medical Center. He assists in medical care for the Carolina Hurricanes.

DOUGLAS B. MCKEAG, M.D., M.S.,
is currently professor and chair of the department of family medicine at Indiana University School of Medicine and director of sports medicine at the National Institute for Fitness and Sports, both in Indianapolis. Dr. McKeag was previously the Arthur J. Rooney chair of sports medicine at the University of Pittsburgh (Pa.) School of Medicine. He serves on the editorial board of the American Academy of Family Physicians and is founder and past president of the American Medical Society for Sports Medicine.

Address correspondence to Scott A. Paluska, M.D., Rex Family Practice of Cary, 1515 S.W. Cary Parkway, Suite 200, Cary, NC 27511. Reprints are not available from the authors.

REFERENCES

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