Sports Topics > Sports Bracing

Bracing Biomechanics
Although joint motion has been described in bioengineering terms as having six degrees of freedom (translation and rotation in the X, Y and Z planes), clinical motion is usually broken down into flexion-extension, lateral bending and rotation. Range of motion depends on flexibility of the muscles, shape and inclination of the bones, ligamentous laxity, and integrity of joint capsule.

The greatest amount of knee motion occurs in flexion and extension. Average knee range of motion is:

• Females: 6-0-143 (6 degrees extension, straight, 143 degrees flexion).
• Males: 5-0-140
• Knee range of motion during walking: 0-5-75

Range of motion at the knee and ankle are significant. As injuries occur, the athlete is subjected to rigorous rehabilitation. Performance with instability may lead to chronic injuries.

Selected Braces
The soft breathable material has gained popularity for treating strain and sprain syndromes. Ankle and knee sleeves (supports) are inexpensive and comfortable, but provide minimal motion restriction. They do provide warmth, compression, promote muscle relaxation and provide a kinesthetic remainder to patients following minor injuries. Sleeves are available in numerous sizes and are well-tolerated by athletes. Secondly, knee sleeves may include hinges with metal extensions. This will minimally restrict movement into bowlegs or knock-knee. Finally, a knee sleeve may include a strap to limit quadriceps tendon excursion. By promoting muscle relaxation, pain related to overuse syndromes may resolve with the use of a knee sleeve.

Ankle braces are either one or two-piece semi-rigid or soft material braces reinforced with stirrups, laces or straps. They are relatively inexpensive and provide better motion control than an ace wrap. In addition, the construction of ankle braces allow for options to restrict motion in certain directions. A thick cotton sock must be used for optimal hygiene or comfort with long-term use.

The most popular braces, ACL and PCL, are rigid one-piece knee braces utilizing a lightweight durable material with incorporated removable foam pads. It is more expensive and provides better motion restriction than a hinged knee sleeve. These braces are available as economical off-the-shelf version or custom-fabricated version to match the anatomical shape more precisely. The off-the-shelf version is similar in concept but lacks durability and unique features that may prove useful in particular sports. Options should be discussed with the orthotist and physician. The brace extends six inches above and below the knee. This improves motion restriction, however compromises comfort and performance. Each of these knee braces may be used to limit the severity of an injury and for postoperative rehabilitation. Treatment for each injury should be individualized and athletes should not compare treatment protocols as an exact science. Therefore, brace treatment for each injury involves the consideration of a number of factors, including injury type, severity, neurological status, risk of instability, body habitus, and the athlete’s potential compliance.

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