Digit-Based Orthoses

Learning Outcomes

Upon completion of this chapter, you will be able to:

1. Describe the common clinical conditions that require a digit-based orthosis.

2. Describe the basic goals for prescribing a digit-based orthosis.

3. Identify pertinent anatomical structures and biomechanical principles involved in a digit-based orthosis and apply these concepts to orthotic design and fabrication.

4. Identify common clinical conditions of the digits that require immobilization with an orthosis.

5. Identify the most commonly selected orthotic designs for digit-based orthoses and describe the rationale for choosing one design over another.

6. After reviewing the instructional videos:

a. Outline the steps involved in the fabrication of a digit-based orthosis.

b. Complete the molding and fabrication steps of a digit-based orthosis.

c. Evaluate the fit and function of a completed digit-based orthosis and identify and address all areas needing adjustment.

7. Identify elements of a client education program following provision of a digit-based orthosis.

8. Describe special considerations of digit-based orthotic design and fabrication for pediatric and special needs clients.

Introduction

The hands and digits are involved in most of our daily functional tasks, and any injury or disability can significantly affect our ability to manipulate objects and perform fine motor tasks. The complex and intricate anatomy of the digits deserves special attention and understanding because improper immobilization methods may prevent a client from regaining full finger motion and strength or lead to permanent finger deformities. The digits often swell after an injury, whether it involves the bones, joints, soft tissue structures, or any combination of these. Reduction of this edema is critical to the management of finger injuries. Orthoses for the digits must take into account the optimal position of healing of each critically involved structure. The practitioner must regularly evaluate each digit-based immobilization orthosis for proper fit and positioning as edema is reduced and passive joint range of motion (ROM) is recovered. This chapter will highlight orthoses for common clinical and pathological conditions involving the digits, including orthoses that protect healing structures as well as functional orthoses that prevent and correct deformities. Orthoses for the thumb are covered in Chapter 5.

A digit-based orthosis will often interfere with complete functional use of the hand, making it challenging for clients to heed the wearing protocols. However, because the consequences of not wearing an orthosis may be serious, the practitioner must educate clients about the importance of doing so. Knowledge of the anatomical structures affected by each specific digit-based orthosis will help practitioners understand how the orthosis will influence these structures, educate their clients on the importance of the orthosis for healing and protection, and assist them in determining appropriate orthosis designs and wearing schedules.

Goals for Use of a Digit-Based Immobilization Orthosis

The goals of a digit-based orthosis will vary depending on each individual client’s needs and the specifics of the clinical condition. Practitioners treating clients with injuries to the finger, such as fractures, sprains, ligament injuries, or other pathologies, must recognize the benefits that immobilization orthoses can offer their clients. These benefits include relief from pain, stability, prevention or correction of deformity, positioning during healing, and improved functional ability. It is critical to perform an ongoing assessment of the client’s current status, particularly in relation to his or her functional ability. Custom-made finger orthoses may require adaptations to meet the client’s changing needs. Inflamed or injured swollen joints require rest and immobilization; however, prolonged immobilization may lead to loss of ROM due to joint stiffness. The use of orthoses may help prevent the development of soft tissue and joint contractures and may improve function, allowing the client to maintain independence (Box 9-1).

When fabricating a digit-based immobilization orthosis, the practitioner must consider the specific clinical condition or diagnosis and the expected clinical outcome following orthotic use, then use sound clinical reasoning to select the most appropriate design. As discussed, the particular design chosen depends on multiple factors. The orthosis can be placed volarly or dorsally depending on the involved structures and the client’s needs (Figures 9-1A and 9-1B). The orthosis might be placed dorsally over the middle phalanx and volarly over the distal phalanx. A tip protector can be fabricated to protect the fingertip after injury or amputation (Figure 9-1C). The orthosis might be a circumferential design encompassing both volar and dorsal sides of the digit or be an oval shape over the middle and proximal phalanges (Figure 9-1D). There are many unique approaches to orthoses for the digits.

Clinical Conditions and Wearing Schedules

This section describes common clinical conditions where a digit-based orthosis might be prescribed and the current evidence supporting this orthosis as an appropriate intervention strategy. Readers are encouraged to review the references provided for additional details regarding each clinical condition and search current research databases for updated evidence as it becomes available.

ARTHRITIC CONDITIONS

Similar to issues in the other joints of the upper extremity, both rheumatoid arthritis (RA) and osteoarthritis (OA) can affect the digits with decreased motion, pain, joint instability, and weakness (Figure 9-2). Radiographic evidence of both RA and OA demonstrates significant changes in bony alignment and structure.

Rheumatoid Arthritis

As discussed in Chapter 3, RA is an autoimmune disease that commonly affects the wrist and small joints of the hand and digits and usually occurs bilaterally. The most commonly seen finger deformities from RA are swan neck and boutonniere.

Clients with RA will likely have additional joint involvement, such as the wrist, thumb, and MCP joints, which may require the fabrication of orthoses that address these joints. However, often the first complaints may involve only the digits, and use of digit-based orthoses can assist in protecting the involved joints and potentially minimizing further deformity.

Swan Neck Deformity

Swan neck deformity is characterized by hyperextension of the PIP joint and flexion of the DIP joint. Clients with RA commonly have swan neck deformity, along with other deformities of the hand and fingers (Figure 9-3). This deformity can be either fixed, meaning it is not possible to passively correct the deformity, or flexible, meaning it is possible to passively correct the deformity. This can severely affect the client’s ability to actively flex the PIP joint and make it difficult to grasp larger objects. Finger orthoses are typically provided for clients with swan neck deformities when the finger is passively correctable, even if all of the digits are affected, and studies have demonstrated that these orthoses do improve function.

Practitioners may fabricate custom-made orthoses from thermoplastic materials or order them through several commercial companies. The orthosis is typically made from two connected oval-shaped rings that are joined at an angle to each other that corresponds to the joint axis of the PIP joint. This design prevents full PIP joint extension but allows the client to actively flex his or her PIP joint within the orthosis.

When fabricating the orthosis, the ovals should encompass as much of the length of the proximal and middle phalanges as possible for leverage and to optimize mechanical advantage of the orthosis.

Some clients may present with hyperlaxity of the PIP joints and appear to have a swan neck deformity. However, if the condition is not permanent nor disabling, there is no need to intervene, and orthotic intervention is not necessary.

Boutonniere Deformity

A boutonniere deformity consists of flexion of the PIP joint and hyperextension of the DIP joint. It is caused by an interruption of the central slip of the extensor tendon where the lateral slips separate and the head of the proximal phalanx pops through the gap like a finger through a button hole; thus the name from boutonnière, which is French for button hole. The deformity prevents full extension of the digit and interferes with the ability to grasp and release objects, place the hand in a pocket or flat on the table, or even don gloves (Figures 9-4 and 9-5). An orthosis is used to keep the PIP joint straight. Boutonniere deformity in clients with RA is caused by inflammation of the joints, bone erosion, joint destruction, and damage to surrounding ligaments and tissues. As will be discussed later in the chapter, boutonniere deformity may also occur as a result of an injury to extensor mechanism in zone III. Although the mechanism of injury for a boutonniere deformity caused by RA is different from that caused from injuries to the extensor mechanism in zone III, the orthotic management is similar, but the wearing schedule may differ.

Osteoarthritis

OA is a wear-and-tear degenerative condition where the cartilage lining the articular joint surfaces is affected by repeated stress on the joints as a client ages or from repetitive stress. As discussed in Chapter 5, the thumb carpometacarpal joint is the most common joint affected by OA in the hand. The second most common site of OA in the hand is the DIP joint. It is subject to considerable stress during prehensile tasks, which can lead to degenerative changes with aging. It is a common condition, affecting up to 20% of men and women over the age of 40 years. OA may affect only one joint in the body, but it is more common to have the condition on both sides.

A specially designed digit-based orthosis can help with both RA and OA symptoms by supporting the painful finger joint in a resting and comfortable position to reduce pain and provide joint stability during activities of daily living (ADL) tasks. The specific goals of an orthosis for this condition are pain reduction, joint protection during ADL, and optimizing functional use of the affected hand by stabilizing the finger joints.

Wearing Schedule

Similar to the recommended wearing schedule for a thumb immobilization orthosis, the recommended wearing schedule of the digit-based immobilization orthosis for clients with arthritis is to wear as needed during periods of inflammation, swelling, and pain. Clients should be encouraged to remove the orthosis periodically to perform gentle ROM exercises and hygiene. When the inflammatory episode has resolved or diminished, clients can reduce orthosis use. For some clients, wearing the orthosis only during activities or only at night may be the appropriate schedule. Use clinical reasoning and discussion with clients to develop individual treatment plans.

Evidence

Level II

• Kennedy, D., Fiona, W., Carlisle, K., Honeyfield, L., Satchithananda, K., & Vincent, T. (2014). Splinting of the distal interphalangeal joint reduces pain and improves extension at the joint: Results from the splint-OA study. Journal of Hand Therapy, 27(3), e1.
  
  
  
  • This is an abstract describing a prospective, radiologist-blinded, controlled trial of custom splinting of the DIP joint conducted with 26 subjects with symptomatic hand OA. All subjects had at least two affected DIP joints. A custom gutter splint was worn on consecutive nights for 3 months, with clinical assessment and measurement of joint deviation by digital plain radiograph at baseline and after 3 months. The average pain (primary outcome measure) and worst pain scores in the intervention joint were significantly lower at 3 months compared with baseline. Short-term DIP joint splinting is a safe, simple, inexpensive treatment modality that reduces DIP joint pain and improves joint extension.
  
  
• Li-Tsang, C. W., Hung, L. K., & Mak, A. F. (2002). The effect of corrective splinting on flexion contracture of rheumatoid fingers. Journal of Hand Therapy, 15(2), 185-191.
  
  
  
  • The authors looked at 22 clients with arthritis and compared the effects of dynamic versus static orthoses to improve function and deformity. Both groups of clients demonstrated improved function and grip strength and decreased contractures. The orthoses were designed for PIP flexion contracture management and were worn for a minimum of 6 hours per day.

Level V

• Adams, J., Hammond, A., Burridge, J., & Cooper, C. (2005). Static orthoses in the prevention of hand dysfunction in rheumatoid arthritis: A review of the literature. Musculoskeletal Care, 3(2), 85-101.
  
  
  
  • The authors conducted a literature review to examine the evidence for immobilization orthoses as an intervention for clients with RA. They cite the results of several studies that indicate that orthoses contribute to decreased pain and inflammation, increased joint stability, and improved function. The authors also attempt to explain how the immobilization orthoses function in relation to the disease process of RA. They mention the limitations of the studies, including the lack of randomized clinical trials and the variability of the disease and its effects on individuals.
  
  
• Beasley, J. (2012). Osteoarthritis and rheumatoid arthritis: Conservative therapeutic management. Journal of Hand Therapy, 25(2), 163-172.
  
  
  
  • This Level V paper states that the goal of an orthosis worn during periods of acute inflammation in the joint helps to reduce joint friction and prevent excessive joint loading limiting joint motion. Excessive movement in unstable arthritic joints can cause increased discomfort and lead to further instability. The author refers to additional studies that have reported that wearing an orthosis decreases pain and increases function during daily activities in patients with arthritis.
  
  
• Van der Giesen, F. J., Nelissen, R. G., van Lankveld, W. J., Kremers-Selten, C., Peeters, A. J., Stern, E. B., … Vliet Vlieland, T. P. (2010). Swan neck deformities in rheumatoid arthritis: A qualitative study on the patients’ perspectives on hand function problems and finger splints. Musculoskeletal Care, 8(4), 179-188.
  
  
  
  • This literature review looks at three specific splint designs for deformities commonly seen in clients with RA: ulnar drift, swan neck, and boutonniere. The authors examine the evidence for the use of orthoses in the treatment of each of these deformities and recommend early intervention with orthoses when the deformities are still flexible and easily corrected. They propose an evidence-informed approach to the treatment of clients with RA in which clinicians use their clinical experience and examine the available evidence to make treatment choices.

MIDDLE AND DISTAL PHALANGEAL FRACTURES

Fractures can occur in any of the finger bones (proximal, middle, or distal phalanges). Maintenance of fracture reduction (setting of the fractured segments together) is a primary goal of orthotic treatment and may dictate postinjury management, such as limitation of early mobilization of the digit. Use of a custom fabricated digit-based immobilization orthosis is often prescribed to stabilize and protect the bones during the healing process, either with conservative management or following surgery. A hand-based orthosis might be used for proximal phalangeal fractures, especially when multiple digits are involved. (See Chapter 7 for more details on orthotic management of proximal phalangeal fractures.) Often, a middle or distal phalangeal fracture can be managed with a digit-based immobilization orthosis. Typically, treatment of nondisplaced fractures of the middle phalanges requires immobilization for 6 to 8 weeks in joint extension. The physician may initially prescribe a digit-based immobilization orthosis to immobilize and protect the fracture or following cast removal for protection. An orthosis provides protection while the client works on regaining joint mobility (Figure 9-6).

Wearing Schedule

The appropriate wearing schedule of a digit-based immobilization orthosis for clients with fractures of the phalanges is full-time for protection and support until the fracture has healed. The preferred positioning for optimal healing is with the PIP and DIP joints in extension. This protects the length of the collateral ligaments, which may shorten if the joints are positioned in flexion. As discussed, fracture healing may take as long as 6 to 8 weeks. An immobilization orthosis might also be used following cast removal and is worn for protection while the client regains finger mobility. The client may be permitted to remove the orthosis for periods of gentle ROM exercises and hygiene if the fracture is stable.

Evidence

Level V

• Cannon, N. M. (2003). Rehabilitation approaches for distal and middle phalanx fractures of the hand. Journal of Hand Therapy, 16(2), 105-116.
  
  
  
  • This Level V paper highlights the importance of communication with the referring physician to appreciate the exact location of the fracture site and understanding each type of fracture, fixation, and the course of fracture healing to best handle the clinical picture of affected tissues, edema, and adhesions in the healing finger.
  
  
• Hardy, M. A. (2004). Principles of metacarpal and phalangeal fracture management: A review of rehabilitation concepts. Journal of Orthopaedic and Sports Physical Therapy, 34(12), 781-799.
  
  
  
  • The author explains the bone-healing process and outlines the various fixation methods for fracture stability. The author also stresses the need for intervention techniques that address the soft tissue injuries related to the bony injuries. Early controlled motion protocols that manage edema, wounds, scarring, and motion are critical. Two important data facts must be obtained from the referring physician: the date of the fracture and the method of fixation. The fracture date starts the bone-healing timetable, and the method of fixation helps to clarify when and how to begin motion. The goals of therapy are to begin early mobilization yet maintain fracture stability.

TUFT FRACTURE

A tuft fracture refers to a crush-type injury to the tip of the distal phalanx, resulting in multiple fracture fragments and a very painful fingertip. The tip of the finger should be immobilized in a fingertip protector orthosis for 2 to 3 weeks to allow for healing, but circumferential types of orthoses should be avoided because they may be restrictive and tight (see Figure 9-1C).

FINGER JOINT INJURIES: PROXIMAL INTERPHALANGEAL JOINT COLLATERAL LIGAMENT SPRAIN

Finger sprains are injuries that cause a stretching and tearing of the ligaments of the fingers. The most common causes of finger sprains are sports injuries and falls on the hand. Finger sprains are classified as grades I, II, and III, with grade III being the most significant injury, including a disruption of the ligament fibers and joint instability (Box 9-2).

Wearing Schedule

Grade I collateral ligament injuries of the PIP joint are treated initially by immobilization and edema control. When edema and pain are reduced, buddy strapping or taping is commonly used to protect the injured joint, but allow flexion and extension (Figure 9-7). Buddy strapping are fabricated from either Velcro strips (Velcro BVBA) and/or low-temperature thermoplastic material (LTTM). They are applied over the proximal phalanx and over the middle phalanx of the injured digit and the adjacent digit, allowing for motion at both the PIP and DIP joints. A layer of gauze can be placed between the digits to prevent the breakdown of the skin. Apply the buddy strapping loosely to avoid cutting off the blood flow and sensory input to the digit. It is important to have the client perform isolated DIP flexion exercises while wearing the buddy strapping to promote gliding of the lateral bands and the flexor digitorum profundus tendon.

Acute grade II injuries can be treated conservatively with immobilization in slight flexion of the PIP joint for comfort. Physicians commonly prescribe a digit-based extension block orthosis to allow for active flexion but protected remobilization, depending on stability of the joint. The arc of motion can be gradually increased to full extension over 3 to 4 weeks. Buddy strapping might be applied while wearing the extension block orthosis. The orthosis is discontinued after 4 weeks, but buddy tape use is allowed with active flexion and extension and return to full function over 6 to 8 weeks.

Surgery is the typical treatment for grade III injuries to restore joint stability and alignment. Restricted motion with a dorsal extension block orthosis and buddy strapping would be an appropriate postoperative treatment protocol.

Evidence

Level V

• Chinchalkar, S. J., & Gan, B. S. (2003). Management of proximal interphalangeal joint fractures and dislocations. Journal of Hand Therapy, 16(2), 117-128.
  
  
  
  • This Level V paper proposes an assessment method for the management of complex finger PIP joint injuries based on the directional forces causing the injury and the associated soft tissue structures involved. The rehabilitation program is guided by understanding the injury-causing forces and the associated structures. Common complications and their management are also discussed.
  
  
• Leggett, J., & Meko, C. (2006). Acute finger injuries: Part II. Fractures, dislocations, and thumb injuries. American Family Physician, 73(5), 827-834.
  
  
  
  • The authors discuss various finger and joint injuries and appropriate evaluation methods, primary treatment, and interventions. This article provides an informative review of different injuries to the fingers and has excellent diagrams outlining the anatomy of each injured part.

PROXIMAL INTERPHALANGEAL JOINT FLEXION CONTRACTURES

Differences in the volar surface and dorsal surface of the PIP joint’s unique anatomy may contribute to the development of PIP joint flexion contractures following injury. The volar plate of the PIP is made up of strong fibrocartilaginous material and contributes to the stability of the volar joint capsule while also preventing dorsal dislocations. Any injury of this structure or close to this structure limits PIP extension because of scar tissue. The scar tissue shortens the fibers of the volar plate and helps to pull the joint into increased flexion.

Wearing Schedule

The most common orthotic treatment for a PIP joint flexion contracture is the serial cast or serial orthosis. This refers to a PIP extension orthosis (from LTTM or plaster of Paris) fabricated with the joint held in maximum extension and worn continuously for several days or up to 1 week without removal by the client. When the client returns to the clinic, the orthosis is removed, and joint passive stretching along with modalities (physical agent modalities such as moist heat, paraffin wax, or ultrasound) are performed. The orthosis is remolded in an effort to maintain any new gains and increased PIP extension. The key points for success are maximizing the extension within the orthosis without causing tissue breakdown and also maximizing the uninterrupted duration of wear. The amount of time the joint is held in this position is known as the total end range time (TERT). The LTTM should have memory if it is to be reused every time.

Evidence

Level II

• Glasgow, C., Fleming, J., Tooth, L. R., & Hockey, R. L. (2012). The long-term relationship between duration of treatment and contracture resolution using dynamic orthotic devices for the stiff proximal interphalangeal joint: A prospective cohort study. Journal of Hand Therapy, 25(1), 38-47.
  

  Glasgow, C., Fleming, J., Tooth, L. R., & Peters, S. (2012). Randomized controlled trial of daily total end range time (TERT) for Capener splinting of the stiff proximal interphalangeal joint. American Journal of Occupational Therapy, 66(2), 243-248.

  
  
  
  
  • The authors looked at the TERT of orthotic wear for 22 clients with extension deficits of the PIP joint who received a dynamic PIP extension orthosis. They then compared the finger ROM in clients who wore the orthosis for 6 to 12 hours per day versus the finger ROM in clients who wore the orthoses for 12 to 16 hours per day. The authors found that most of the clients were unable to adhere to the longer splint wearing regimen of 12 to 16 hours per day. However, wearing a dynamic PIP extension orthosis does help clients regain finger motion, but clients’ personal factors and ADL demands need to be taken into account when prescribing a time-based wearing protocol for the orthosis.
  
  
• Prosser, R. (1996). Splinting in the management of proximal interphalangeal joint flexion contracture. Journal of Hand Therapy, 9(4), 378-386.
  
  
  
  • The author conducted a study on 20 patients with PIP flexion contractures who received a dynamic orthosis that applied a 250 g force to the distal end of the middle phalanx. Each participant in the study was instructed to wear the orthosis for 8 to 12 hours per 24 hours for 8 weeks, followed by a 2- to 3-week weaning period. Statistical analysis showed that the time of orthotic intervention was the only statistically significant factor affecting outcome. Dynamic splinting was an effective form of treatment for PIP flexion contracture.
  
  
• Flowers, K. R., & LaStayo, P. (1994). Effect of total end range time on improving passive range of motion. Journal of Hand Therapy, 7(3), 150-157.
  
  
  
  • The authors of this randomized, clinical trial tested the theory of TERT to see if the amount of passive ROM gained from using an orthosis was related to the amount of time spent in the end-range position. For this purpose, the authors looked at two groups of patients with PIP flexion contractures. One group of patients wore digital extension casts for 6 days and subsequent casts for 3 days, whereas the other group of patients wore the initial digital extension casts for 3 days and the subsequent casts for 6 days. The results showed that there is a relationship between gains in passive ROM and the amount of time a stiff joint is held in its maximal end-range position.

Level III

• Uğurlu, Ü., & Özdoğan, H. (2016). Effects of serial casting in the treatment of flexion contractures of proximal interphalangeal joints in patients with rheumatoid arthritis and juvenile idiopathic arthritis: A retrospective study. Journal of Hand Therapy, 29(1), 41-50.
  
  
  
  • The authors of this retrospective study sought to evaluate the outcomes of serial casting in the treatment of PIP joint flexion contractures in patients with RA and juvenile idiopathic arthritis. They analyzed the records of 18 patients treated with serial casting. The changes in the finger joints were studied and compared statistically using t-tests. A total of 49 fingers were serially casted with plaster of Paris over a 14-year period. This intervention resulted in significant (26.8 degrees; P < .001) reduction in the PIP joint extension loss. Small but statistically significant losses in flexion were associated with these gains (P < .001). The authors conclude that, although this was a small retrospective study, serial casting is an effective method to correct flexion contractures in PIP joints in selected patients with arthritis.

VOLAR AND DORSAL PROXIMAL INTERPHALANGEAL JOINT DISLOCATIONS

The most commonly dislocated (separated) joint in the hand is the PIP joint (Figure 9-8). The direction of dislocation is named for the distal bone segment: A dorsal dislocation refers to dorsal displacement of the middle phalanx, whereas a volar dislocation refers to volar displacement of the middle phalanx. A dorsal dislocation is more common than a volar dislocation and can injure the volar plate or cause an avulsion fracture of the middle phalanx.

Wearing Schedule

The treatment following a dorsal dislocation after reduction or realignment of the bone and joint surface is to hold the PIP in an immobilization orthosis in about 30 degrees of flexion for 2 to 4 weeks to allow healing. This position prevents the PIP joint from dislocating with active extension. A dorsal extension block orthosis or a circumferential orthosis is typically fabricated for this condition, and active flexion of the PIP joint is permitted (see Figure 9-1B).

Related posts:

Orthotic Fabrication: Principles and Practice Orthoses for Mobilization The Basics Wrist Immobilization Orthoses Wrist and Hand Immobilization Orthoses Anatomical and Biomechanical Principles of Orthotic Intervention

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