What type of orthotics support weakened body parts correct deformities and prevent joint movement?

Dynamic and Passive Control

All orthoses control spinal motion by a combination of dynamic and passive mechanisms. Dynamic control describes the significant role of intrinsic musculature in actively stabilizing the spine and is a major component in the effect of most orthoses. It has been demonstrated experimentally that opposing muscular forces significantly stiffen the spinal column, increasing its load-bearing capacity.8 If isolated from its muscular support, the osseous and ligamentous spinal column holds only 2 kg of axial load before failure by buckling.2 In terms of a column model, muscular action directly affects the modulus of elasticity and relative cross-sectional area of the composite spinal column. Orthoses promote muscular stabilization through tactile feedback, guiding the patient to maintain proper positioning of the body. Pressure at the orthosis-skin contact site produces a reminder to maintain a specific position and limit unwanted gross body motion.4,12-15 The patient therefore is able to prevent undesirable motion of the spine using only intrinsic muscular support guided by the orthosis. Stiffer, more securely worn appliances are more effective at limiting motion because of the heightened sensation of resistance that the stiffer appliance produces. Sypert and others noted that the effectiveness of an appliance is directly related to the level of its discomfort.3,4 However, brace discomfort may also contribute to higher levels of noncompliance.

Passive mechanisms for motion control are important in three-point bending mechanisms and are derived from intrinsic properties of the orthosis itself such as design, size, and material composition. Two common design elements of all orthoses are similar in principle to internal fixation constructs and include end-stabilizing elements (e.g., thoracic bands, pelvic bands) and longitudinal members or uprights that interconnect the end elements.1 Passive mechanisms apply reactive forces to the body that oppose physiologic and pathologic movement of the head or trunk; viscoelastic forces of ligaments, discs, and muscles; and gravitational force.16 As summarized by White and Panjabi,7 passive mechanical strategies form the basis for most orthotic techniques and include (1) spinal distraction, (2) fluid compression, (3) balanced transverse force application, and (4) skeletal fixation. Most appliances use a combination of techniques for motion control.

Articular and nonarticular orthoses

Orthoses are classified into two broad categories: articular and nonarticular. Articular orthoses, the most common type of fabricated orthoses, are those that cross one or more joints. Examples of articular orthoses include a wrist immobilization orthosis, proximal interphalangeal (PIP) joint extension mobilization orthosis, and elbow flexion restriction orthosis. The word articular is implied in the orthosis description and is not necessary to be included in the name of this type of orthosis.

Nonarticular orthoses do not cross a joint; instead, they stabilize the body segment to which they are applied. The ASHT recommends that clinicians include the term nonarticular before an orthosis description because its intended use is not implied. For example, an orthosis used to stabilize the humerus would be called a nonarticular humeral orthosis, and an orthosis designed to stabilize a metacarpal would be called a nonarticular metacarpal orthosis. Without this designation, the orthosis fabricator may not know whether to include or exclude proximal or distal joints in the process of designing an appropriate orthosis.

Types of Orthoses

Orthoses can be divided into two categories: orthoses for immobilization and orthoses for mobilization. Orthoses for immobilization exert a static force on a specific body part. An example of this would be an immobilized wrist joint in a wrist cock-up orthosis (Fig. 7.1B). There are no moveable parts in the orthosis, and the wrist joint itself is at rest in the orthosis. On the other hand, orthoses for mobilization are constructed with moveable components and can be adjusted depending on the specific construction type and purpose of the orthosis.1 Orthoses for mobilization can be further categorized into dynamic, static progressive, and serial static orthoses. Dynamic orthoses incorporate elastic components, coils, or springs that allow movement of the client’s joint(s) while wearing the orthosis (Fig. 7.2). These orthoses might be indicated in postoperative treatment protocols, to assist with weak muscles, or to increase passive joint range of motion. Static progressive orthoses include inelastic components that typically pull on stiff joints or other tight tissues to allow progressive changes in joint position. This can be an effective intervention when someone has a very stiff joint after trauma or surgery (Fig. 7.3A and B).1 A serial static orthosis is worn by a client over a specific time period and is then remolded to accommodate positive changes in joint motion or positioning (Fig. 7.4). The goals are quite different for orthoses for immobilization versus orthoses for mobilization. You should always consider the goal of your orthosis before you begin to design and fabricate it on your client. The goal should be the first thing you consider.

Goals of orthoses for immobilization and mobilization are highlighted in Box 7.1 and Box 7.2.

Orthoses

Orthoses are the mostly widely studied and effective intervention for decreasing pain during hand use in people with OA.55,60,62,79-81 Orthoses are used to protect joints and help reduce pain by statically holding the joint(s) in place. They decrease load by positioning the affected joint(s) during ADL hand use and by supporting the joint(s) to prevent distortion from deforming forces. Supportive orthoses are typically worn during the day during activity; however, some clients report pain reduction with nighttime use only. Systematic reviews and meta-analyses of randomized controlled trials have shown that orthosis use alone improves function and decreases pain.60,62,79

There are almost as many orthosis styles for thumb CMC joint OA as there are studies. However, most suggest a hand-based orthosis that allows the IP freedom of movement.82 If the MP joint is included in the orthosis it is usually flexed at 10 to 20 degrees, and the thumb is positioned in a 3-point pinch positioning with the index and middle fingers. The choice of orthosis should be adapted to the type of activity the client partakes in and adapted to individual differences.55 If the orthosis fits well, the client will report decreased pain with pinch activities, as it is stabilizing the CMC joint in the proper position. Radiographs during active pinch can verify if the orthosis is properly maintaining the metacarpal on the trapezium.82

Regarding orthotic intervention for the IP joints, I have had success in reducing pain and improving function with Silipos sleeves and custom gutter or circumferential orthoses that include only the involved joint. These are worn during activity to protect the joint from further trauma. In addition, a custom 3-point style orthosis can be used to correct lateral deviation at the PIP or the DIP, and help make hand use more comfortable.

General Considerations

Knee orthoses (KOs) are a very commonly prescribed class of brace both because of the high prevalence of knee osteoarthritis and the high rate of knee injuries in recreational and professional athletes.1,16,30,45,52 KOs are designed to provide stability, prevent instability, limit motion, and/or provide off-loading of the knee joint. Most include both a medial and lateral upright with either a free motion or adjustable knee joint. A KO is primarily indicated when the ankle and foot are fully functional such that a KAFO is not required. The indications for provision of a KO are further delineated in Box 12.1.

Orthoses

Orthoses can be used to facilitate wound healing by immobilizing the wound and protecting key structures in the hand. It is important to note that not all hand burns require orthotic intervention. The decision to use or not to use an orthosis depends on the depth and extent of the burn and the client’s ability to tolerate positioning, exercise, and function. Most superficial partial-thickness burns do not require an orthosis because healing is completed within 3 weeks. An orthosis should be considered if healing is compromised, tendons are exposed, or there is a significant limitation in active extension or flexion of hand joints.23 In some cases an orthosis may be indicated for a client who is unable to actively move the hand or for a client who may move too aggressively. Orthoses are used more often with deeper burns. Despite static orthotic intervention in the early phases of wound healing to prevent burn scar contracture, the incidence of contracture has been reported as 5% to 40%, with weak evidence supporting their effectiveness.25

Clinical Pearl

In the emergent and early acute phases, edema can lead to poor positioning and the classic burn deformity of wrist flexion, metacarpophalangeal hyperextension, interphalangeal flexion, thumb adduction, and a flattened palmar arch.

Unless otherwise indicated, immobilize the hand with the wrist in extension, the metacarpophalangeal (MP) joints in flexion, the interphalangeal (IP) joints in extension, and the thumb in abduction. Slight wrist extension encourages MP flexion by means of a tenodesic effect, and MP flexion in turn puts tension on the collateral ligaments to prevent shortening. Proximal interphalangeal (PIP) joint extension protects the vulnerable extensor mechanism, and thumb abduction maintains the first web space. Considerable variation in ideal joint angles can be found in the literature.26 A consensus calls for wrist extension of 15 to 30 degrees, MP flexion of 50 to 80 degrees, full IP extension or slight flexion, thumb abduction midway between radial and palmar abduction, MP flexion of 10 degrees, and full thumb IP extension (Fig. 30.2).13,18,23 For isolated burns to the palmar surface, position the wrist in neutral to slight extension, the fingers in full extension and abduction, and the thumb in radial abduction and extension.23 Never force joints into the ideal position. Although prefabricated orthoses are available, custom orthoses made from perforated material are preferable because they allow a more precise fit and can be adjusted to accommodate changes in edema and joint mobility. Orthoses can be secured by gauze wraps, elastic bandages, or straps.

Precaution. Carefully monitor and adjust how the orthosis is secured to ensure there is no vascular compromise.23

For clients with significant involvement of the IP joints, the surgeon may opt to place Kirschner wires across the joints to obtain complete immobilization and protection of the extensor mechanism.3

Orthoses may also be used in the later phases of recovery to prevent or correct scar contracture. To prevent contracture, use static orthoses, placing joints in positions opposite the direction the scar will pull. Common burn scar contractures in the hand are wrist flexion from volar burns, wrist extension or flexion from dorsal burns, thumb adduction from a burn to the first web space, MP and IP extension from dorsal hand burns, and MP and IP flexion from volar hand burns. Have the client wear the static orthosis at night only, if possible, to avoid compromising functional hand use during the day. Use serial static orthoses, dynamic orthoses (also known as “elastic mobilization”), or static progressive orthoses (also known as “inelastic mobilization”) to regain ROM with joint and/or scar contracture. Place scars under tension in an elongated position to promote new cell growth, collagen remodeling, and tissue lengthening.14,27

Circumferential burns may require alternating use of different orthoses to address all scars.18

INTRODUCTION

Spinal orthoses are external devices which are typically applied circumferentially about the body with the intent of altering spinal motion. Lumbar supports fashioned from tree bark have been found in pre-Columbian cliff dwellings, and the use of orthoses was described both by Hippocrates and Galen.1 Centuries later, in the United States alone, some 1.8 million people use a spinal orthosis in any given year.2

Orthoses have several potential functions, including prevention of deformity, correction of deformity, enhancement of function, limitation of motion to allow healing, relief of pain, and spinal support. Orthoses can be designed to restrict gross spinal motion, restrict individual segmental motion, reduce the loading force on the spine, correct a spinal deformity, and to prevent the progression of an existing deformity. In this chapter, the use of cervical and thoracolumbar spinal orthoses will be discussed primarily in relation to treatment of pain and providing spinal support.

Immobilization Protocol

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Orthosis: When the repaired extensor tendon is treated with immobilization in the initial phase of tendon healing, a postoperative splint applied by the physician, a finger length cast, or a thermoplastic orthosis made in therapy is applied to hold the PIP joint in full extension. If the lateral bands were injured in addition to the EDC tendon, the DIP is held in full extension as well. The orthosis is worn full time until 3 to 4 weeks postoperatively (Fig. 26.5).

Exercises: In an immobilization protocol, the repaired tendon is protected in extension at all times during the first 3 to 4 weeks. In the early phase of tendon healing, the client moves only the joints that are not restricted within the orthosis.

Introduction

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Orthosis: An externally applied device used to modify the structural or functional characteristics of the neuromusculoskeletal system. Alternate definition: An apparatus used to support, align, prevent, or correct deformities or to improve the function of movable parts of the body.

During static stance and during ambulation, the lower extremities are subjected to external forces and moments. During normal function, these forces and moments are resisted or controlled by internal structures of the body. These structures include skeletal segments, ligamentous connections, and muscle-tendon units.

When internal structures fail, orthoses can modify external forces and moments to allow the body to function in a “normal” manner.

An external device used to support or improve function of the foot and ankle can take many physical forms. This orthotic can be as simple as a felt pad placed under the metatarsals, or as sophisticated as a composite brace controlling foot and ankle motions.

Orthotics prescribed for lower extremity pathologies include foot orthoses (FOs), ankle-foot orthoses (AFOs), knee orthoses, and knee-ankle-foot orthoses.

Effect on lower limb biomechanics

Foot orthoses influence lower extremity kinematics and kinetics as well as rearfoot mechanics. Eng and Pierrynowski100 examined the three-dimensional effects of soft foot orthoses during the contact, MSt, and propulsion phases of walking and running on the TCJs, STJs, and knee joints in 10 women with a history of patellofemoral joint pain and forefoot varus or calcaneal valgus greater than 6 degrees. Soft orthoses produced a modest decrease in frontal and transverse plane motion in the TCJs, STJs, and knee joints during walking and running. Knee joint motion in the frontal plane decreased during the early and MSt phases of walking but increased during the contact and MSt phases of running. This work demonstrates the complex coupling of lower extremity kinematics with motions of the STJ; reductions in subtalar motion in the frontal plane have an impact on knee function in both the frontal and transverse planes during walking.

McPoil and Cornwall149 also studied the effects of soft and rigid orthoses on tibial rotation. Ten individuals with documented rearfoot or forefoot deformity ambulated with unposted, premolded, soft orthoses and rigid polyethylene orthoses posted according to the individual’s deformity. Both orthoses decreased the rate and amount of tibial internal rotation during walking. Stacoff and colleagues150 observed the effects of medially posted cork orthoses on calcaneal and tibial motions in five runners. Three-dimensional tibiocalcaneal rotations were assessed after inserting intracortical bone pins into the calcaneus and tibia. Although the effects on eversion and tibial rotation were small and variable, a statistically significant orthotic effect was present for total tibial rotation. The authors, noting that the differences were unsystematic across conditions and were specific to each individual, speculated that the effects of orthoses might be proprioceptive as well as mechanical.

Joseph and colleagues151 studied the relationship between ankle pronation/eversion with excessive knee valgus and risk of anterior cruciate ligament injury in female athletes during drop jumps. Ten female athletes performed drop jump landings with and without a medially posted orthosis. A three-dimensional kinematics of the knee and ankle were measured during the jump. The authors reported a significant decrease in ankle pronation/eversion and knee valgus at IC when the athletes had a medial post in their shoes. Their findings support medial orthotic posts for potentially decreasing the risk of anterior cruciate ligament injury. Tillman and colleagues152 evaluated the impact of orthotic posting on the tibial rotation induced by jumping from a 43-cm-high platform in seven women without foot malalignments by using three conditions (shoes only, shoes with orthoses posted 8 degrees medially, and shoes with orthoses posted 8 degrees laterally). Tibial internal rotation increased by 2.6 degrees with laterally posted inserts and decreased by 3.1 degrees with medially posted inserts. Nester and colleagues153 examined the effects of medially and laterally wedged orthoses on the kinematics of the rearfoot, knee, hip, and pelvis during walking, reporting main effects on the rearfoot, with minimal effects at knee, hip, or pelvis. Laterally wedged orthoses increased pronation and decreased laterally directed ground forces, whereas medially wedged orthoses decreased pronation and increased the laterally directed ground forces.

Williams and colleagues154 examined the effects of graphite “inverted” orthoses (orthoses used to provide more aggressive control of pronation by using an inverted position as opposed to a more vertical orientation), standard graphite orthoses posted with a 4-degree medial wedge, or shoes alone in 11 runners who had been initially fitted with the standard orthoses for various lower extremity injuries. Surprisingly, the three conditions produced no significant differences in the peak rearfoot eversion or rearfoot eversion excursion.

A significant decrease in the rearfoot inversion moment and work with the inverted orthosis suggests this orthotic design might decrease demand on the structures controlling eversion. However, increased internal tibial rotation and an adduction moment at the knee occurred with the inverted orthosis, raising concern that potential for lateral stress increases with this aggressive orthotic approach.

Kuhn and colleagues155 examined quadriceps femoris Q-angle in 40 men with bilateral pes planus or hyperpronation syndrome before and after the insertion of foot orthotics. Of the 40 men, 39 had a significant decrease in bilateral Q-angle in the direction of correction after insertion of full-length flexible orthotics. Men with asymmetrical Q-angle measurements showed significantly greater symmetry of Q-angle measures after orthotic placement. Kuhn and colleagues155 noted that hyperpronation can cause the tibia to internally rotate, leading to femur internal rotation and resulting in lateral tracking of the patella. They concluded that insertion of full-length flexible orthotics in men with hyperpronation significantly improves quadriceps femoris Q-angle.

Stackhouse and colleagues156 studied biomechanics during running in 15 individuals with normal alignment. Individuals ran with both rearfoot and forefoot strike patterns and with and without semirigid orthoses with 6 degrees of rearfoot posting. The orthoses did not change rearfoot motion in either strike pattern but did reduce internal rotation and genu valgum by approximately 2 degrees through most of the stance phase. Although no statistically significant reduction occurred in the inversion moment and inversion work, the authors believed that the reductions they found were clinically relevant and might explain the reduction of injuries seen when orthoses are used.

Although evidence supports the fact that foot orthoses can and do influence lower extremity kinematics and kinetics, the variability of individual responses makes it difficult to determine exactly which biomechanical effects will occur. This variability also makes it difficult to forecast who is likely to benefit from orthotic intervention. Efficacy of foot orthoses is not solely the result of altered rearfoot kinematics, as proposed by Root. The contribution of the neuromuscular system to the effect of orthotic intervention is now being considered.