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Am Fam Physician. 2000;61(2):411-418

A more recent article on braces and splints for common musculoskeletal conditions is available.

See related patient information handout on knee braces, written by the authors of this article.

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.

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.1,2,69 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.


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.1012 Some researchers have concluded that prophylactic knee braces significantly reduce MCL injuries,1113 while others have noted few beneficial effects with regular use.10

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.

Brace typeIndicationsContraindicationsReported benefits/evidenceRisks/limitations
Prophylactic knee bracesMCL 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 excessive preloading of MCL
Limited speed and athleticism
False sense of security for previously injured knee
Brace-related contact injuries to other players
Functional knee bracesReduce 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 bracesPatellar 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)

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.


Currently, most prophylactic knee braces use unilateral or bilateral bars with hinges. Examples of both types are shown in Figure 1.

The rightsholder did not grant rights to reproduce this item in electronic media. For the missing item, see the original print version of this publication.

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.

Manufacturer/telephone numberKnee brace typeName of productAdditional informationCost*
dj Orthopedics
ProphylacticDonJoy Protective Knee GuardUnilateral support$ 44
ProphylacticDonJoy PlaymakerBilateral support125
FunctionalDonJoy LegendPresized fit325
FunctionalDonJoy DefianceCustom fit525
PatellofemoralDonJoy On-Track79
Omni Scientific
ProphylacticAnderson Knee Stabilizer 1Unilateral support110
ProphylacticAnderson Knee Stabilizer 2Bilateral support120
FunctionalOmni Scientific SpectrumPresized fit375
FunctionalOmni Scientific Avant GuardCustom fit550
PatellofemoralOmni Scientific Sport Sleeve40
McDavid Knee Guard, Inc.
ProphylacticMcDavid Protective Knee GuardUnilateral support45 to 60
ProphylacticMcDavid Pro StabilizerBilateral support48 to 60
Bledsoe Brace Systems
FunctionalBledsoe Ultimate CIPresized fit325
PatellofemoralBledsoe Sport Max55 to 89
DePuy Ortho Tech
FunctionalOrtho Tech Ultimate ControllerPresized fit280
FunctionalOrtho Tech MontanaCustom fit700
PatellofemoralOrtho Tech Neopatellar Stabilizer36
Seattle Orthopedic Group
FunctionalLenox Hill Precision FitPresized fit339
FunctionalLenox Hill Spectra LightCustom fit440
Townsend Design
FunctionalRebel SeriesPresized fit500 to 800
FunctionalAir SeriesCustom fit750 to 1250
PatellofemoralNeoprene Sport Brace58 to 99
Palumbo Orthopedic
PatellofemoralPalumbo Patella Stabilizing Brace39
PatellofemoralOrtho-Care Body Flex34
Pro Orthopedic Devices, Inc.
PatellofemoralDr. “180-U” Universal Patellar Brace35


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.

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


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.


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.

The rightsholder did not grant rights to reproduce this item in electronic media. For the missing item, see the original print version of this publication.

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.


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

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.9,1820 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


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.


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.

The rightsholder did not grant rights to reproduce this item in electronic media. For the missing item, see the original print version of this publication.

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

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
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.


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.

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