The History and Cur nt Use of Knee Brace Technology

WE#T SCRIBER, EdD, ATC Department of Exercise and Sport Sciences Ithaca College

Injury rates and ible sleeve that was secured above the amount of time and below the knee with velcro lost from sports straps or tape.

participation are About the same time, Dr. consistently greater for the knee James Nicholas and associates than for any other joint (Ander- began developing the Lenox Hill son & Hall, 1995; Arnheim & derotation brace. They used a cus- Prentice, 1997). Therefore it is not tom fitted design that relied on a surprising that considerable time, effort, and funding have been di- rected at developing and refining the various braces intended to protect against knee injury.

With the increased use and de- velopment of knee braces during the past three decades, it is diffi- cult to keep abreast of all knee brace technology.

This article discusses different types of braces and reviews their development and present use. The controversy of knee brace ef- ficacy will be covered briefly, along with how the technology evolved. Some of the current thinking and recommendations regarding the use of knee braces are also discussed

Looking Back

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these "functional" braces are still manufactured today and are rec- ommended following certain types of knee joint injuries.

In the late 1960s, Dr. Robert McDavid developed a splint-like, single-hinged knee brace that was positioned along the outside of the knee, the goal being to protect a previously injured knee

In the early 1970s a few braces i ~ c ~ a r e n , 1984). The-flat splint were available that were typically was made of a durable polycar- used for knee injuries. Some of bonate (Lexan) sewn inside a flex-

3-point fixation system with me- dial and lateral support bars-a monocentric hinge, a medial ful- crum disc, and a rigid pretibial bar (Drez, 1985). The basic design re- mained the same for years and was one of the most utilized func- tional braces.

Another popular brace that was developed in the late 1970s was the Anderson knee stabler (Anderson et al., 1979). This lat- eral brace was a double-hinged, single-sided brace with steel stays and foam rubber pads over con- toured aluminum alloy flanges at each end. It was attached by tap- ing and its purpose was to reduce the chance of reinjury by prevent- ing significant valgus stress of the knee.

The McDavid and Anderson prototype braces rapidly became more popular as they began to be used and marketed for the pur- pose of preventing injury.

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July 1998 The MfesslsnaB dsurraal far AShlieSic Miners and Therapists, 7

Classification of Wnee Braces

Many manufacturers (e.g., Mac- Gregor, Bike, Wilson, Cramer) began producing lateral preven- tive braces. Some anticipated that these would become a standard part of the equipment for football (McLaren, 1984).

Because of a concern that there was minimal objective data on the multitude of knee braces flooding the market at that time, the American Academy of Ortho- pedic Surgeons (AAOS) spon- sored a seminar on knee braces in 1984 to obtain data from manufac- turers, physicians, and engineers as to their design and effective- ness. In view of the data presented at the seminar, the Sports Medi- cine Committee suggested that the following knee brace classifi- cations be used:

Prophylactic knee braces- those designed to prevent or reduce the severity of knee injuries (Photo 1). Functional knee braces- those designed to provide stability for unstable knees (Photo 2). Rehabilitative knee braces- those designed to allow pro- tected range of motion for injured knees after surgery or other treatment (Photo 3) (Drez, 1985).

Pmghglladic Wnee Braces

Theoretically, these lateral braces absorb valgus forces to the knee and minimize the number and/ or severity of medial knee injuries. Examples of *prophylactic *knee braces include the McDavid brace (Arco), Anderson knee stabler (Omni), Stromgren, the PKG (protective knee guard) by

DonJoy, the Muellerhinge, and a lateral knee brace by Cramer.

The basic design for these braces has not changed much over the years. They include some type of lightweight (10 oz) lateral bar (steel, aluminum alloy, plas- tic, or polycarbonate material) with single, dual, or polycentric hinges with hyperextension stops. The braces are attached via tape, polypropylene or neoprene sleeves, or elastic straps.

The cost of these braces is typi- cally $25 to $50. Many athletes continue to use the braces today in the hope of preventing knee injuries, even though there is not much scientific evidence to sup- port this view.

As a multitude of preventive braces were being developed and marketed in the early 1980s, numerous investigations began to address and test for the re- commended characteristics of the AAOS. At first, anecdotal evidence and testimonials on behalf of preventive knee braces seemed encouraging.

After early use of lateral braces for preventing new injury to existing knee injuries (Ander- son et al., 1979; McLaren, 1984), some began using the same braces on noninjured football players solely to prevent injury. Some studies reported a decrease in knee injuries (Hansen et al., 1985; Sitler, 1992). Others found either no difference or even an increase in knee injuries for braced athletes (Paulos et al., 1986; Scriber & Matheny, 1990; Teitz et al., 1987).

Results such as these pointed to four potentially adverse effects from lateral bracing: preloading; shift of the brace center axis; brace slippage; and brace bending to the point of joint contact (Paulos et al., 1986).

Salvaterra et al. (1993) re- ported that certain lateral prophylactic knee braces were not effective in stabilizing the knee joint from a static valgus force. Borsa et al. (1993) addressed the concern of the effect of brac- ing on physical activity and con- cluded that lateral knee braces

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A PHOTO 1 Preventive knee brace.

inhibit muscular and functional performance.

It was reports such as these that led to the current AAOS po- sition. The AAOS states that

"the routine use of prophylactic knee braces currently available has not been proven effective in reducing the number or severity of knee injuries. In some circum- stances, such braces may even have the potential to be a con- tributing factor to injury" (1997, p. 1) .

Because of the tremendous importance of the issue not only from the standpoint of injury pre- vention but also the substantial financial implications relating to brace development, knee brace efficacy is covered more thor- oughly in the article by Sauers and Harter.

Functional knee braces are de- signed to reduce or eliminate functional instability following ligamentous injury to the knee (Ott & Clancy, 1993). They ac- complish this by controlling tibial translation, rotational stress, and extension limitations. They should be applied with relative ease, fit comfortably, not hinder performance, and not predispose the athlete to reinjury.

Currently there are more than 20 varieties of functional knee braces. Some are custom made from a molded cast or paper trac- ing of the patient's knee, others are off-the-shelf. It appears there is no clearcut advantage for using the more expensive custom braces compared to off-the-shelf designs (Beynnon et al., 1992). Examples of functional braces are the Gold- Point, Defiance, and Legend (Donjoy), the CTi, CTi2, and Edge (Innovative Sports), the Avant Garde (Omni), and the Lenox Hill derotation brace (3M).

As noted earlier, some of the current prophylactic braces were initially considered functional when first used. Nicholas and Castiglia are generally credited with devising the first functional knee brace in the late 1960s (Ott & Clancy, 1993).

Their prototype became well known as the Lenox Hill derotation brace. It featured a monocentric hinge, metal-hinged side bars, medial or lateral ful- crum pads, and a pretibial rigid bar that was designed to limit an- terior tibial translation and rota- tion. The brace was held in place by rubber straps proximally and distally with velcro fastenings.

A cast mold of the patient's leg could be sent to the Lenox Hill Brace Shop, where a custom brace

with no special features could be made for approximately $270. Add to this the casting and fitting costs by an orthotist, therapist, or physician, and the patient often paid a lot more. The only major change to this brace was that it was eventually produced with support bars that were as strong but much lighter weight.

The CTi brace by Innovative Sports (1997), another rigid frame support, had medial and lateral polycentric hinges to control knee rotatory instability. Knee paper

A PHOTO 2 Functional knee brace.

tracings were used to customize the brace fit, and this lightweight 15- to 18-oz brace was primarily made up of a carbon fiber tita- nium material. In standard form its initial cost was $385. Modifi- cations of this brace are still avail- able in a variety of options from Innovative Sports.

In addition to the more re- cently developed CTi2 and Edge

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custom braces, a C180 off-the- shelf brace with a thermosensitive rigid frame construction is avail- able. The off-the-shelf versions range from $500 to $800 while the custom models range from $800 to $1,200.

Omni Scientific produces the following custom functional knee braces: Avant Garde, Avanti, TS- 7, and Elite. The Avant Garde has a carbon composite construction with a variable flexion hinge ($510). The Avanti is a lightweight model made from a carbon/ graphite laminate. The TS-7 and Elite are made of aerospace alu- minum for the medial and lateral frames with a custom fiberglass tibial cuff; both list in the $425 range. A nonrigid thigh cuff was developed for the TS-7 to help prevent brace pistoning and soft tissue migration. These custom braces are made from cast molds.

Off-the-shelf models include the Spectrum, whose structure is a graphite fiber composite lami- nate with an aluminum alloy tibial crest for adjustable contour and a near custom fit. The EC1000 is a full-frame brace design. It is desirable when a less functional design is acceptable and cost ($189) is a major consideration (Omni Scientific, 1997).

DonJoy produces functional knee braces that have compared favorably to several others for controlling anterior tibial transla- tion (Cawley et al., 1991). These include the off-the-shelf Gold- Point ($340) and Legend ($320), as well as the custom made Defiance ($525).

Features of the GoldPoint and Legend include a patented 4-point dynamic leverage system for op- posing tibial translation. There are also flexion and extension stops, a removable chamois liner, and

pneumatic condyle pads for com- fort and fit. Although lightweight at 18 oz, the Defiance is the stron- gest of the DonJoy functional braces and is recommended for high collision sports (DonJoy, 1997).

Ott and Clancy (1993) re- viewed a number of studies docu- menting that these functional knee braces do reduce anterior/ posterior translation and rotation at some loads. Other reports

PHOTO 3 Rehabilitative knee brace.

showed less pivot shifting epi- sodes for persons wearing the braces, and some claimed im- proved running and cutting per- formance.

In light of such reports, the AAOS believes that,

"rehabilitative and functional knee braces can be effective i n m a n y t rea tment programs, and . . . this efficacy has been demonstrated by long-term sci- entifically conducted studies" (1997, p. 2).

Rehabilitative knee braces are de- signed to allow protected and controlled range of motion of in- jured knees after injury or surgery (Anderson & Hall, 1995). There is little disagreement that these braces can effectively limit de- grees of flexion and/or extension at the knee. The advantages of early controlled motion during rehabilitation, as opposed to com- plete immobilization, have also been well established (Shelbourne & Nitz, 1990).

Examples of rehabilitative braces are the Bledsoe, Innovative Sports' Sentry, and DonJoy's IROM. Most of these braces range from $100 to $150.

These braces are basically off-the-shelf and are made up of hinge brace arms with foam or polypropylene enclosures for the calf and thigh. The hinges have adjustable stops to control flexion and extension and gener- ally have polycentric or cam-like hinges. Some of the functional braces discussed earlier have range-of-motion stops and have also proven effective as rehabili- tative braces.

The desire to prevent sports inju- ries or at least reduce their sever- ity is not new. The concern about knee injuries has led to the devel- opment of knee braces, the three major classifications being pro- phylactic, functional, and re- habilitative.

Prophylactic braces were de- veloped to prevent knee injuries primarily by absorbing valgus forces to the knee, but their effec- tiveness is uncertain since few scientific reports have supported this claim.

July 1998

Functional braces help pro- vide stability for previously in- jured knee ioints, and there is growing evidence that they are somewhat effective.

Rehabilitative braces allow for controlled range of motion for in- jured knees; they have been effec- tive in allowing early limited motion during rehabilitation.

Although brace technology has changed somewhat, the rea- sons for using braces have not. Design modifications have led to lighter, stronger, and more du- rable materials, and to brace de- signs that accommodate different leg alignments, sizes, and shapes. Brace fit has been improved to prevent slippage.

Overall, brace function and effectiveness appear to be design dependent. In other words, braces of similar design are also similar in function regardless of the manufacturer. As more effective knee braces are developed, ath- letic therapists will be better able to meet their goal of decreasing the number and severity of knee injuries.

American Academy of Orthopedic Surgeons. (1997). AAOS Position Statement: The use of knee braces. http://www.aaos.org/ wordhtml/papers/position/kneebr.htm

Anderson, G., Zeman, S., & Rosenfeld, R. (1979). The Anderson knee stabler. The Physician and Sportsmedicine, 7(6), 125-127.

Anderson, M., & Hall, S. (1995). Sport injury management. Media, PA: Williams & Wilkins.

Arnheim, D., & Prentice, W. (1997). Principles of athletic training (9th ed.). St. Louis: Mosby-Year Book.

Beynnon, B., Pope, M., Wertheimer, C., Johnson, R., Fleming, B., Nichols, C., & Howe, J. (1992). The effect of functional knee braces on strain of the anterior cru- ciate ligament. Journal of Bone and Joint Surgery, 74A(9), 1298-1312.

Borsa, P., Lephart, S., & Fu, F. (1993). Muscular and functional performance characteristics of individuals wearing prophylactic knee

braces. Athletic Training, Journal of the NATA, 28,336-342.

Cawley, l?, France, l?, & Paulos, L. (1991). The current state of functional knee bracing Re- search A review of the literature. Ameri- can Journal of Sports Medicine, 19,226-233.

DonJoy. (1997). DonJoy braces. http://www. srnithnephew.com/

Drez, D. (Ed.) (1985). Knee Braces Seminar Re- port. Chicago: American Academy of Or- thopedic Surgeons.

Hansen, B., Ward, J., & Diehl, R. (1985). The preventive use of the Anderson knee sta- bler in football. The Physician and Sports- medicine, 13(9), 75-81.

Innovative Sports. (1997). Functional knee braces. http://www.isports.com/func. htrnl

McLaren, L. (1984, March). Knee braces are the best friends that a bad--or good-knee ever had. Sports Illustrated, pp. 7-8.

Ornni Scientific, Inc. (1997). Functional knee braces. http:/ /www. omniscientific.com/ tkb.htm1

Ott, J., & Clancy, W. (1993). Functional knee braces. Orthopedics, 16,171-175.

Paulos, L., Drawbert, J., France, P., & Rosen- berg, T. (1986). Lateral knee braces in foot- ball: Do they prevent injury? The Physician and Sportsmedicine, 14(6), 119-124.

Salvaterra, G., Wang, M., Mourehouse, C., &

Buckley, W. (1993). An in vitro biomechani- cal study of the static stabilizing effect of lateral prophylactic knee bracing on me- dial stability. Journal of Athletic Training, 28, 113-119.

Scriber, K., & Matheny, M. (1990). Knee inju- ries in college football: An 18-year report. Athletic Training, Journal of the NATA, 25, 233-236.

Shelbourne, K., & Nitz, P. (1990). Accelerated rehabilitation after anterior auciate liga- ment reconstruction. The American Journal of Sports Medicine, 18,292-299.

Sitler, M. (1992). Role of prophylactic knee and ankle bracing in injuryreduction. Journal of Sport Rehabilitation, 1,223-236.

Teitz, C., Hermanson, B., & Kronrnal, R. (1987). Evaluation of the use of braces to prevent injury to the knee in college football play- ers. Iournal of Bone and Joint Surgery, 69A(1),

Kent Scl-iber is an associate professor in the De- partment of Exercise and Sport Sciences at Ithaca College and is also the supervisor of athletic training. During his 26-year tenure at Ithaca he has worked as an athletic trainer pri- marily with the varsity baseball and football teams.

Dislocators, Separators and Subluxators

The SAWA Shoulder Orthosis is a major advancement in the design of shoulder girdle sup- port. The snug-fitting, lightweight material (under 2 pounds) allows for comfort with movement and at the same time helps protect the Glenohumeral joint from subluxations and dislocations. Its strap

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