Current Evidence and Clinical Recommendations for Their Use

Knee Braces: Current Evidence and Clinical Recommendations for Their Use

Scott A. Paluska

University of Pittsburgh Medical Center-Shadyside, 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

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.

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.

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.

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.

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.

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

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.

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

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.

REFERENCES

1.American Academy of Pediatrics Committee on Sports Medicine. Knee brace use by athletes. Pediatrics 1990;85:228.

2.France EP, Cawley PW, Paulos LE. Choosing functional knee braces. Clin Sports Med 1990;9:743-50.

3.Burger RR. Knee braces. In: Baker CL, Flandry F, Henderson JM, eds. The Hughston Clinic sports medicine book. Baltimore: Williams & Wilkins, 1995:551-8.

4.Ott JW, Clancy WG Jr. Functional knee braces. Orthopedics 1993;16:171-5.

5.American Academy of Orthopaedic Surgeons. The use of knee braces. Document number 1124. Retrieved November 24, 1999, from the World Wide Web: www.AAOS.org/wordhtml/papers/position/ kneebr.htm.

6.Arroll B, Ellis-Pegler E, Edwards A, Sutcliffe G. Patellofemoral pain syndrome: a critical review of the clinical trials on nonoperative therapy. Am J Sports Med 1997;25:207-12.

7.Kramer JF, Dubowitz T, Fowler P, Schachter C, Birmingham T. Functional knee braces and dynamic performance: a review. Clin J Sports Med 1997;7:32-9.

8.Beynnon BD, Pope MH, Wertheimer CM, Johnson RJ, Fleming BC, Nichols CE, et al. The effect of functional knee-braces on strain on the anterior cruciate ligament in vivo. J Bone Joint Surg [Am] 1992;74:1298-312.

9.Cutbill JW, Ladly KO, Bray RC, Thorne P, Verhoef M. Anterior knee pain: a review. Clin J Sports Med 1997;7:40-5.

10.Albright JP, Saterbak A, Stokes J. Use of knee braces in sport. Current recommendations [Editorial]. Sports Med 1995;20:281-301.

11.Albright JP, Powell JW, Smith W, Martindale A, Crowley E, Monroe J, et al. Medial collateral ligament knee sprains in college football. Effectiveness of preventive braces. Am J Sports Med 1994; 22:12-8.

12.Albright JP, Powell JW, Smith W, Martindale A, Crowley E, Monroe J, et al. Medial collateral ligament knee sprains in college football. Brace wear preferences and injury risk. Am J Sports Med 1994;22:2-11.

13.Sitler M, Ryan J, Hopkinson W, Wheeler J, Santomier J, Kolb R, et al. The efficacy of a prophylactic knee brace to reduce knee injuries in football: a prospective, randomized study at West Point. Am J Sports Med 1990;18:310-5.

14.Liu SH, Mirzayan R. Current review. Functional knee bracing. Clin Orthop 1995;317:273-81.

15.Saliba E, Foreman S, Abadie RT. Protective equipment considerations. In: Zachazewski JE, Magee DJ, Quillen WS, eds. Athletic injuries and rehabilitation: Philadelphia: Saunders, 1996: 924-32.

16.Liu SH, Lunsford T, Gude S, Vangsness CT Jr. Comparison of functional knee braces for control of anterior tibial displacement. Clin Orthop 1994; 303:203-10.

17.Wojtys EM, Kothari SU, Huston LJ. Anterior cruciate ligament functional brace use in sports. Am J Sports Med 1996;24:539-46.

18.Timm KE. Randomized controlled trial of protonics on patellar pain, position, and function. Med Sci Sports Exerc 1998;30:665-70.

19.Gulling LK, Lephart SM, Stone DA, Irrgang JJ, Pincivero DM. The effects of patellar bracing on quadriceps EMG activity during isokinetic exercise. Iso Exer Sci 1996;6:133-8.

20.Eckhoff DG, Brown AW, Kilcoyne RF, Stamm ER. Knee version associated with anterior knee pain. Clin Orthop 1997;339:152-5.

21.Greenwald AE, Bagley AM, France EP, Paulos LE, Greenwald RM. A biomechanical and clinical evaluation of a patellofemoral knee brace. Clin Orthop 1996;324:187-95.

22.Papagelopoulos PJ, Sim FH. Patellofemoral pain syndrome: diagnosis and management. Orthopedics 1997;20:148-57.

23.Shellock FG, Mink JH, Deutsch AL, Molnar T. Effect of a newly designed patellar realignment brace on patellofemoral relationships. Med Sci Sports Exerc 1995;27:469-72.

24.Maenpaa H, Lehto MU. Patellar dislocation: the long-term results of nonoperative management in 100 patients. Am J Sports Med 1997;25:213-7.

25.Maurer SS, Carlin G, Butters R, Scuderi GR. Rehabilitation of the patellofemoral joint. In: Scuderi GR, ed. The patella. New York: Springer-Verlag, 1995:156-9.

Table 1

Knee Brace Classification and Summary

Brace type Indications Contraindications Reported benefits/evidence

Risks/limitations

Prophylactic MCL protection against To limit rotational control

Reduction of frequency and Injuries increased by excessive

knee braces valgus knee stresses in ACL-deficient knees

severity of MCL injuries preloading of MCL

Re-injury protection Unstable knees requiring

following valgus knee Limited speed and athleticism

after previous MCL operative therapy

stresses False sense of security for

injury Supporting cruciate ligaments

previously injured knee

Athletes at high risk during rotational

stresses Brace-related contact injuries

for MCL injury Enhanced knee proprioception

to other players

Functional Reduce translation and Unstable knees requiring

Laboratory evidence of Reported effects on translation

knee braces rotation following operative therapy

reduced tibial rotation and and rotation disappear at

ACL injury Complicated multi- knee AP

translation physiologic levels of use

Additional support after directional knee injuries

Subjective reports of Increased energy expenditure

ACL surgery such as posterolateral decreased

pain, enhanced and decreased agility

Support for mild to corner injuries

performance, and improved False sense of confidence

moderate PCL or MCL confidence during

athletics following ACL reconstruction

instability Control of knee Brace-related

contact injuries

hyperextension to other

players

Augmented knee

proprioception

Patellofemoral Patellar subluxation Knee disorders unrelated

Improved patellar tracking Subjective benefits exceed

knee braces and/or dislocation to the patellofemoral

during knee flexion and objective findings

Patellar tendonitis joint extension Increased

skin irritation and

Chondromalacia of the Knee translation or Dissipated

lateral patellar lesions

patella rotational control forces

Relatively insignificant pain

Postsurgical effusion Unstable knees requiring Decreased

anterior knee relief with regular brace

control operative therapy pain syndromes

wear

Subjective reports of Less effective

than conservative

decreased pain, enhanced

therapy (simple stretching

performance and improved

and strengthening)

confidence during athletics

MCL = medial collateral ligament; ACL = anterior cruciate ligament; PCL

= posterior cruciate ligament; AP = anteroposterior.

Table 2

Knee Braces-Manufacturers and Product Information

Manufacturer/

telephone number Knee brace type Name of product Additional

information Cost*

dj Orthopedics Prophylactic DonJoy Protective Unilateral

support $ 44

800-336-6569 Knee Guard

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 Prophylactic Anderson Knee Unilateral

support 110

800-875-9080 Stabilizer 1

Prophylactic Anderson Knee Bilateral support 120

Stabilizer 2

Functional Omni Scientific Presized fit 375

Spectrum

Functional Omni Scientific Custom fit 550

Avant Guard

Patellofemoral Omni Scientific – 40

Sport Sleeve

McDavid Knee Prophylactic McDavid Protective Unilateral

support 45 to 60

Guard, Inc. Knee Guard

800-237-8254 Prophylactic McDavid Pro Stabilizer Bilateral

support 48 to 60

Bledsoe Brace Systems Functional Bledsoe Ultimate CI Presized

fit 325

800-527-3666 Patellofemoral Bledsoe Sport Max – 55 to

89

DePuy Ortho Tech Functional Ortho Tech Ultimate Presized fit

280

800-227-1554 Controller

Functional Ortho Tech Montana Custom fit 700

Patellofemoral Ortho Tech Neopatellar – 36

Stabilizer

Seattle Orthopedic Functional Lenox Hill Precision Fit

Presized fit 339

Group Functional Lenox Hill Spectra Custom fit 440

800-248-6463 Light

Townsend Design Functional Rebel Series Presized fit 500

to 800

800-432-3466 Functional Air Series Custom fit 750 to 1250

Patellofemoral Neoprene Sport Brace – 58 to 99

Palumbo Orthopedic Patellofemoral Palumbo Patella –

39

800-292-7223 Stabilizing Brace

Ortho-Care Patellofemoral Ortho-Care Body Flex – 34

800-821-1303

Pro Orthopedic Patellofemoral Dr. “180-U” Universal –

35

Devices, Inc. Patellar Brace

800-523-5611

*-Prices are approximate costs furnished by the manufacturers. Actual

cost to consumer may be higher.

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.

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.

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