Orthotic Treatment Considerations for Arthritis and Overuse Syndromes in the Upper Limb

Key Points

Many health care professionals commonly see patients with some form of arthritis, especially rheumatoid arthritis (RA) and osteoarthritis (OA). RA and OA can be highly disabling conditions that can affect many aspects of a person's life (e.g., physically, psychologically, socially, economically). The severity of RA and OA can range from mild to severely disabling.
Osteoarthritis is a heterogeneous condition in which biomaterial properties of articular cartilage or bone are abnormal or there is excessive biomechanical loading, such as may occur after trauma to a joint or to normal cartilage or bone, or both.
Rheumatoid arthritis is a progressive, chronic, systemic disease marked by inflammatory changes of the joints, tendons, and their sheaths resulting in pain, weakness, and dysfunction. Inflammation caused by proliferative synovium results in erosions of articular cartilage, articular bone, and soft tissue. This can cause rupture of tendons and the weakening of ligaments around the involved joints. In the hand, this eventually leads to muscle and tendon imbalance, ligamentous laxity, instability, and subluxation or complete dislocation of the joints.
Orthoses are used as a treatment for persons with arthritis in the upper limb(s) to reduce pathomechanical stress, inflammation, and pain.
Other goals of orthotic treatment of arthritis are to correct a deformity, rebalance tendons, support and stabilize joints during function, protect joints from increased stress/demand, prevent joint contractures, immobilize unstable joints, increase range of motion, increase function, and position joints for occupational performance.
Lateral epicondylitis, cubital tunnel syndrome, carpal tunnel syndrome, de Quervain tenosynovitis, and trigger finger (stenosing tenosynovitis) represent common overuse disorders of the upper limb.
The anatomy, symptoms, and conservative orthotic treatment options for these overuse disorders are reviewed.
A comprehensive treatment approach to the management of overuse conditions is necessary, involving orthoses used in conjunction with other treatment options, such as antiinflammatory medications, steroid injections, ergonomic modifications of work activities and the workplace, and exercise.

Section I

Orthotic Treatment Considerations for Arthritis in the Upper Limb

Introduction

Many health care professionals, including orthotists and occupational therapists, commonly see patients with some form of arthritis, especially osteoarthritis (OA) and rheumatoid arthritis (RA). OA is the most prevalent form of arthritis followed by RA, and each form can produce highly disabling conditions that can affect many aspects of a person's life (e.g., physically, psychologically, socially, economically). OA (or degenerative joint disease) is a slowly evolving heterogeneous condition in which biomaterial properties of articular cartilage or bone are abnormal or there is excessive biomechanical loading, such as may occur after trauma to a joint or to normal cartilage or bone. It was proposed that “wear and tear” on the cartilage was the cause of the condition, but new research reveals the more likely cause is damage to the whole synovial joint and to subchondral bone due to an active disease process, with joint tissue destruction and aberrant repair as a result of alterations in cellular function.

Once cartilage begins to break down, excessive mechanical stress begins to fall on other joint structures. Eventually thinning and loss of the articular cartilage can result in exposure of the subchondral bone, which becomes denser as the surface is worn and polished. Joint space narrowing can occur as the cartilage thins. As the disease progresses, sclerosis of the subchondral bone occurs as new bone is formed in response to the now excessive mechanical load. New bone also forms at the joint margins (osteophytes) with the end result being mechanical joint failure and varying degrees of loss of joint function. Because cartilage is not innervated, pain is not perceived until the bone or other structures surrounding the joint are involved. Pain with activity is most likely due to mechanical factors. Inflammation is typically localized to the joint. Loss of flexibility is usually associated with significant progression of the disease, such as soft tissue contractures, intraarticular loose bodies, large osteophytes, and loss of joint surface congruity. As the single most common joint disease, OA has an estimated prevalence of 60% in men and 40% in women later in life after age 65 years. In the upper limb, OA commonly develops in the hands and digits, and it may localize to specific joints in a unilateral fashion (i.e., affecting one extremity at the wrist, hand, or fingers). The overall incidence is expected to dramatically increase over the next 20 years as the population ages.

RA is a progressive, chronic, systemic autoimmune disease marked by inflammatory changes of the joints, tendons, and their sheaths resulting in pain, weakness, and dysfunction. Two primary risk factors of RA are gender (female prevalence) and age (peak onset between 20 and 50 years). Inflammation caused by proliferative synovium results in erosions of articular cartilage, articular bone, and soft tissue structures. The degradation of connective tissue and bone typically begins insidiously and slowly progresses over time. In its more advanced state, rupture of tendons and the weakening of ligaments around the involved joints are evident. In the upper limb, this eventually leads to muscle and tendon imbalance, ligamentous laxity, instability, and subluxation or complete dislocation of involved joints. Presentation of RA in the upper limb typically localizes to specific joints in a symmetric and bilateral fashion (i.e., affecting wrists, hands, and fingers). The course of the disease is rather unpredictable, and patients typically experience periods of exacerbations and remissions. In the upper limb, the small joints of the hands are most often affected. There is no known cure for RA or OA, and although these conditions are usually irreversible, treatment options are available. Orthoses are commonly beneficial for the treatment of arthritis in the upper limb. To provide effective outcomes, the orthotist, occupational therapist, and other rehabilitation professionals need an understanding of the underlying mechanics to determine the appropriate orthosis design and to interpret proper fit and function of the device. The next section provides an applied approach to this topic but is not intended to be comprehensive.

Overarching Principles of Orthosis Design and Function

The overarching goal of orthotic treatment of arthritis is to reduce pathomechanical stress on the affected joint complex, which in turn likely reduces inflammation and pain. Reducing pathomechanical stresses to the joint complex typically involves therapeutic methods such as correcting a joint or limb segment deformity, rebalancing tendons, supporting and stabilizing joints during function, protecting joints from increased stress/demand, preventing joint contractures, increasing function, increasing range of motion (ROM), positioning joints for occupational performance, and immobilizing unstable joints. To accomplish these therapeutic methods through the use of orthoses requires a fundamental understanding of key biomechanical and engineering concepts, such as force systems, moment arm, material stiffness properties, pressure, shear/friction, and intimacy of fit between orthosis and limb. Each of these topics are described in turn.

Force Systems

Orthoses are used as “force systems” that are applied to the body ultimately to control motion of various skeletal segments and joints. Usually an orthosis applies several forces that interact and resolve to create the desired orthotic biomechanical motion control. Coupling of forces is a critical feature, especially with respect to a three-force system, which is one of the most fundamental mechanical principles incorporated into an orthosis. For example, a balanced three-force system to restrain wrist flexion involves one force located at the wrist directed volarly and two counterbalanced forces directed dorsally. Of the two counterbalanced forces, one is located distal to the wrist and the other proximal to the wrist. The sum of the balanced three-force system prevents wrist flexion motion ( Fig. 16.1 ). In fact orthoses can be designed to provide one or more biomechanical motion controls described as resist, stop, lock, hold, variable, free, or assist.

Figure 16.1, Schematic of a wrist–hand orthosis exhibiting a balanced three-force system to prevent wrist flexion. The direction and magnitude of each force vector is illustrated by a solid black arrow .

Moment Arm

The management of forces in an orthosis may be complicated by many interrelated components affecting how the forces are applied to the body. The criteria for orthotic design are founded on basic mechanical principles: a moment arm is the distance from the respective joint axis to the location where the force is applied. To provide the same level of joint motion control, orthoses with short moment arms must produce higher forces at the limb–orthosis interface than orthoses with long moment arms. This can pose a challenge for the treatment of arthritis due to the presence of pain and inflammation at joint structures. Maximizing the length of the orthosis (and inherently the moment arm) is generally preferred over shorter orthotic devices to reduce the magnitude of forces at the limb–orthosis interface. This allows the orthosis to provide the necessary magnitude and distribution of forces to control joint and limb segment movement while ensuring the wearer's comfort and tolerance. For example, an individual with OA develops an elbow flexion contracture due to muscle imbalance between elbow flexors and extensors. To prevent the progression of elbow flexion, an elbow orthosis to resist flexion would be more effective if the forearm and arm components extend as far away from the elbow joint as possible to maximize leverage and reduce the magnitude of force at the points of contact ( Fig. 16.2 ).

Material Stiffness Properties

Material stiffness is an important factor in influencing the efficiency of force transfer in an orthosis. Stiff materials possessing a low modulus of elasticity (i.e., metals, thermosetting resins, high temperature thermoplastics) resist bending and generally provide effective force transmission to body structures. Lower limb orthoses with materials possessing high modulus of elasticity have demonstrated effective resistance to bending. On the opposite spectrum, the use of flexible materials (i.e., elastic fabrics) that are highly compliant are less effective in restricting bending and limb movement. When flexible materials are incorporated in an orthosis, it reduces force transmission to body structures and provides less restriction of motion. In cases in which larger forces are required for the orthosis to achieve motion control (i.e., stop flexion to prevent progression of flexion contracture in arthritic elbow), rigid materials are required. Conversely, when less force is required to achieve the desired motion control (i.e., moderate to minimal resistance to metacarpophalangeal [MCP] ulnar deviation in rheumatoid hand), elastic flexible materials are better suited.

Pressure

Because orthoses interface with the skin and subcutaneous tissue, a force coupling occurs in the form of pressure and shear, which are important considerations in orthotic design. Pressure is defined as force per unit area. The surface area of the force application region by an orthosis can be increased to redistribute force over a larger area or decreased to concentrate the force over a smaller area ( Fig. 16.3 ). Pressure occurs when the direction of forces between the orthosis and limb are normal (i.e., perpendicular). Because persons with arthritis commonly possess tenderness at or near joint structures, maximizing the area of contact between the orthosis and limb segment to reduce interface pressure is desired.

Figure 16.3, Cross-section of a forearm and forearm orthosis illustrating contact area of fit between the orthosis and the periphery of the forearm. (A) Small contact area due to gapping between orthosis and limb structures, which increases interface pressure. (B) Larger contact area due to total contact between orthosis and limb structures, which decreases interface pressure.

Shear and Friction

Shear stresses may damage skin and other tissues that are particularly vulnerable in arthritis. They occur when the direction of forces between the orthosis and limb are tangential (i.e., not perpendicular, such as sliding). To reduce the shear forces of an orthosis, either the motion between the orthosis–limb interface (i.e., skin and subcutaneous tissues) or the coefficient of friction of the orthosis material interface must be decreased. Reducing motion (i.e., sliding) may be achieved by adjustments to improve the intimacy of fit between the orthosis and limb (e.g., altering the shape of half shells, installing pads to minimize gapping, installing straps to improve suspension). Introducing a material interface as a barrier between the orthosis and skin may reduce the coefficient of friction and reduce shear stresses. For example, an interface sock can reduce the coefficient of friction to protect skin from direct contact with the orthosis. Another approach to reduce shear stress is to add an interface material to the orthosis that possesses mechanical properties with low friction coefficient values (i.e., Shearban).

Intimacy of Fit Between Orthosis and Limb

An intimate fit between the orthosis and limb segment is important in providing suspension to prevent migration, to maintain positioning for force transfer between the orthosis and anatomical structures and to provide a broad area of force application. Closely matched contours between the orthosis and limb typically increase the area of the force application, thereby reducing the magnitude of pressure to structures (see Fig. 16.3B ). Applying this concept to orthotic treatment of arthritis means distributing orthosis contact in areas of the limb that are tolerant to pressure (e.g., fascia structures just proximal or distal to the articulation). This will mitigate forces in areas of the limb that are less pressure tolerant (e.g., inflamed, tender, or painful tissues at the joint and joint capsule).

Formulating the Orthotic Treatment Plan

Formulating the orthotic treatment plan for a person with arthritis requires a thorough knowledge of the disease process, biomechanical principles, and upper limb anatomy. Also, to improve communication among the prescribing provider and rehabilitation specialist and to standardize the approach for orthotic prescription formulation, the American Academy of Orthopedic Surgeons developed a biomechanical analysis systems for the upper limb. This system incorporates the fundamental procedures by which an orthotist assesses and formulates a prescription recommendation for an orthosis as part of a treatment plan. The underlying principle behind the biomechanical analysis system is to match the person's functional impairment with the biomechanical motion controls incorporated in an orthosis that target the person's functional goals without disturbing normal function.

The biomechanical system uses a technical analysis form as a guide to document the assessment and identify the biomechanical variables and other parameters that are key to formulation of the orthotic prescription recommendation. Methods used in the biomechanical analysis system are simplified to a three-step approach:

1
Describe the functional impairments and detail the functional deficits
2
Establish treatment objectives
3
Determine orthotic recommendation

Describe the Functional Impairments and Detail the Functional Deficits

An assessment of the patient's limitations of any body systems function should be described in relative detail, followed by a summary statement. This involves identification of the major impairments to skeletal and articular surfaces including associated structures such as the joint capsule and ligaments. Neuromuscular function and tendon alignment should be assessed to determine the extent of muscle weakness or imbalances, which can lead to contractures or other joint deformities. Neurologic status should be assessed to determine the patient's sensory function such as the distribution and type of pain. Assessment of skin integrity and the presence of nodules or other changes in condition (i.e., turgor, dryness, etc.) should be noted. Vascular status such as pulses and tissue perfusion is also important to note. Coordinated functional assessment of limb structures to determine dexterity, grasp and pinch, and noting the presence of joint or limb segment deformities that may impair shoulder, elbow, wrist, hand, or digit function should be noted.

Establish Treatment Objectives

The extent of destruction to the joint and any subsequent deformity will influence the magnitude of force imposed between the body structure and orthosis. Additional information that will assist the clinician in formulating treatment objectives are understanding the patient's goals, expectations, attitudes, and preferences; their living and working environments, social support, and safety issues; and their ability to understand and follow instructions for care and use of the orthosis. All of these factors influence development of the treatment objectives.

Determine Orthotic Recommendation

There are several guidelines for an orthotic recommendation. First, describe the joint(s) that the orthosis encompasses (e.g., first MCP, proximal radio-ulnar). Next, describe the motion control in the cardinal plane. Use orthotic motion control mechanisms terminology (i.e., resist, stop, lock, hold, variable, free, or assist—e.g., stop elbow flexion). Next, describe the limb segments to be encompassed by the orthosis (e.g., wrist–hand orthosis, elbow orthosis). Implementing a systematic approach to identifying and describing the problem followed by a description of the orthotic treatment will facilitate communication and development of the rationale for orthotic treatment. The next section provides a survey of common functional impairments and deficits, treatment objectives and orthotic recommendations for the arthritic elbow, wrist, thumb, and fingers.

Despite the best orthotic treatment recommendation for the patient with an arthritic upper limb, successful clinical outcomes are only made possible through an integrated team approach including the patient, his or her significant others, and health care providers. It is important to note that the patient and the caregivers bring key physical, psychological, social, and functional components to the orthotic process and should be considered key members of the team.

Assessment and Orthotic Treatment of RA and OA at the Elbow Joint

Background and Functional Impairments

Nearly half of patients with RA and approximately 5% of patients with OA present with degeneration of the elbow. OA most commonly affects the dominant arm of men in their 50s. In this population, repetitive strenuous arm use appears to be a factor and has been reported in heavy laborers, throwing athletes, and weight lifters. The degenerative effects of RA and OA create a loss of articular cartilage, destruction of the articulating surfaces, and loss of bone in the ulnotrochlear and radiocapitellar articulations at the elbow. Typical radiographic findings are osteophyte formation, bone destruction, joint narrowing, and irregular surfaces of the coronoid and olecranon fossa ( Fig. 16.4 ). Persons with RA may specifically exhibit effusions, synovial thickenings, and erythema with loss of motion in flexion and extension as well as pronation and supination of the proximal and distal radioulnar joints. Flexion contracture is almost always evident in the arthritic elbow. Pain, limited motion, and crepitus worsen as the disease progresses. In persons with RA, the clinician should look for the presence of rheumatoid nodules, which may reside in the olecranon bursa, the extrinsic wrist extensor muscles, wrist, and MCP joints of the hand. These granulomatous lesions usually occur in areas of repeated mechanical pressure such as over the extensor surface of the elbow and extensor surface of the fingers, wrist, or elbow. Nodules are usually asymptomatic but can become tender or lead to skin breakdown and infection. Collateral ligament laxity from RA may also cause instability in the elbow as evidenced by the radiographic drop sign at the ulnohumeral joint. The drop sign is evident on a lateral radiograph as a measureable increase in ulnohumeral distance of greater than 4 mm ( Fig. 16.5 ). It is present after simple or complex dislocations treated with or without surgery and is indicative of persistent instability of the elbow joint. If the ulnohumeral joint continues to “sag” and is not treated, it will likely lead to continued destructive changes in the ulnohumeral joint, such as olecranon fossa spurring and loss of elbow extension or ratcheting elbow from loose bodies in the joint, which may cause progression of elbow flexion contractures. As such, a positive drop sign can be detrimental to regaining elbow motion and function. In some cases an olecranon bursitis may be present as a noticeable protrusion in persons with triceps tendinitis ( Fig. 16.6 ).

Figure 16.4, Lateral radiograph of elbow exhibiting joint degeneration due to osteoarthritis.

Figure 16.6, Olecranon bursitis. (A) External appearance. (B) Radiographic appearance.

Orthotic Treatment

Important factors that influence the extent of orthotic treatment of the arthritic elbow are the presence of pain, joint inflammation, osteophytes, and rheumatoid nodules. Care must be taken to minimize contact pressure between the orthosis and skin in the area of rheumatoid nodules because interface pressure by the orthosis may result in skin breakdown or stimulate additional nodule formation. Advanced cases of arthritis typically present with greater deformity, pain, and inflammation. In these cases, the magnitude of force applied by the orthosis to produce therapeutic motion control is dependent on patient tolerance.

Generally, the orthotic treatment goal for the patient with arthritic elbow is to prevent progression of the joint deformity and minimize limb segment malalignment. Reducing deformity reduces the imbalance of forces within the joint, joint capsule, ligaments, and muscle–tendon units that cross the joint. In particular, halting the progression of elbow flexion contracture, protecting painful ROM, providing joint stability in cases where the joint has become weakened (i.e., collateral ligament damage), and minimizing wear on articular surfaces by promoting more natural ROM are important treatment goals.

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