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Low-Temperature Thermoplastic Splints/Orthoses Made by Therapists: An Overview of Current Practice
By Judy C. Colditz, OTR/L, CHT, FAOTA Therapists who treat patients with hand problems
frequently use low-temperature thermoplastic materials for the
construction of hand splints/orthoses 1-9 .
Splints/orthoses are used by therapists to meet many different
clinical goals and are altered frequently in response to changes in
motion, edema, strength, or joint mobility in the hand. The use of
splints/orthoses is an integral part of the therapy process and the
construction and fitting of splints is a skill required of
therapists to help the patient regain functional use of the
hand.
NOTE: Since therapists commonly use the term "splint" and
orthotists commonly use the term "orthosis" when referring to
custom-fitted devices molded to the hand, this article will use
these terms interchangeably. Previous authors have advocated these
terms be used synonymously 4,10,11 .
History
 Prior to the advent of low-temperature
thermoplastic materials in the 1970s, therapists used plaster of
Paris, leather, metal, and high-temperature plastics to construct
hand splints/orthoses. The use of these materials required
significant construction time after measurements and/or molds were
taken of the patient. Multiple patient visits and fittings were
usually required. Adjustments and modifications were cumbersome and
time-consuming. With the introduction of low-temperature
thermoplastic materials, the splint/orthosis could be molded
directly to the patient and completed in one patient visit while
other therapeutic intervention occurred. Modifications and
adjustments to the orthosis could also be completed quickly and
efficiently. At the same time as the advent of low-temperature
thermoplastic materials, the specialties of hand surgery and hand
therapy rapidly developed in the United States. The growth of these
specialties greatly expanded the use of custom-fitted
low-temperature splints/orthoses with hand patients.
This article intends to serve as an overview of the current
state of the art use of low-temperature thermoplastic
splints/orthoses in the treatment of hand patients.
Splinting for Protection and Mobilization: Early Motion
Following injury to the hand, maintaining joint motion and glide
of tissue layers is required to maintain the complex mobility of
the hand. The therapist's job is to thoroughly understand the
anatomy, the injury, and the surgical repair in order to create a
balance of protecting healing structures while safely maintaining
as much movement as possible 12 .
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Figure 1. This custom molded splint/orthosis protects the healing 5th metacarpal fracture from external forces. The patient works actively to maintain proximal and distal interphalangeal joint motion while in the splint and periodically removes it to gently, actively flex and extend the metacarpophalangeal joint. |
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The striking beneficial effects of early motion following injury
have led to immediate post-operative involvement of the therapist
even in the most severe trauma patients 13-18 . For
example, standard treatment of stable fractures of the hand often
consists of a custom-molded removable splint/orthosis, which allows
early motion while providing protection to the healing fracture
during use of the hand. (See figure 1). Additionally, management of
repaired flexor or extensor tendon injuries is now often begun on
an immediate protected active motion protocol, which includes a
protective splint/orthosis 19 . (See figure 2).
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Figure 2. Following a complex open crush injury to the dorsum of the hand that included laceration of all extensor digitorum communis (EDC) tendons, this dynamic splint allows limited metacarpophalangeal (MP) joint flexion but assists with MP joint extension. This splint/orthosis permits safe early active motion by the patient, maximizing glide of the EDC tendons while protecting them from excessive force. |
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The purposes of the splint/orthosis become
intertwined with the goals of therapy, and at each therapy visit
the splint/orthosis and its use is reevaluated. As tendon healing
proceeds or bony union is achieved, the patient is weaned from the
splint/orthosis. During this weaning period, the splint/orthosis
may undergo numerous adjustments, freeing up joints to allow
additional motion, repositioning joints for better tendon glide, or
refitting the splint/orthosis may occur to accommodate edema
reduction or change of contour of a wound area.
Splints/orthoses are also used to immobilize selected anatomical
areas when inflammation of a ligament, tendon, or nerve is
apparent. Immobilization via an external device imposes rest to the
inflamed tissues. This rest, coupled with oral or local
anti-inflammatory medications, usually allows most inflammation to
subside without surgical intervention.
Splinting for Scar Management
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Figure 3. Following the initial period of healing, mobilization splints/orthoses are used to slowly coax the stiff joints into the desirable position. This patient sustained a complex injury resulting in multiple fractures and soft tissue injuries. In this example the molded piece on the volar aspect of the replanted thumb maintains thumb abduction and extension in the face of the contracting soft tissue scar while the dynamic portion regains joint motion. |
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All traumatic hand injuries create the potential
for scar to limit joint motion and tendon gliding. Large surface
injuries including skin avulsions, burns, and crush/mangle injuries
require many months of vigilant attention to assure motion is
maintained in the face of contractile scar. Complex surgical
reconstruction may include full and/or partial skin grafts as well
as sophisticated flaps, which include blood vessels and nerves. As
these grafts heal and contract, tissue length and mobility is
maintained by prolonged positioning of the affected part by an
immobilization splint/orthosis.
The contouring of healing tissue with positioning and the
positive pressure of the splint/orthosis is achieved by multiple
splints/orthoses, which are changed as the scar matures.
Invariably, joint stiffness (see below) accompanies these complex
injuries and the concurrent goal of regaining motion is balanced
with the need to maintain scar length and tissue elasticity. (See
figure 3).
Treatment of burns to the hand or other parts of the body
requires attentive positional splinting for many months to
encourage the scar tissue to mature in a lengthened position. (See
figure 4).
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Figure 4. This child sustained bilateral burns when he grasped his sister’s hot curling iron. Many months of molded positional splinting regained joint motion and prevented the need for surgical release. The before and after of the left hand is shown. |
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Splinting to Regain Muscle Strength and Tendon Glide
Injury to one or more of the three major peripheral nerves of
the upper extremity begins a long period of recovery. Following
surgical repair of the nerve, it may be months or years before the
maximum sensory and motor return is achieved. During this time, the
use of a splint/orthosis keeps denervated muscles from remaining in
an over-stretched position, prevents joint contractures from
developing, prevents development of strong muscle substitution
patterns, and maximizes the functional use of the hand
20 . Although isolated nerve injuries can occur, many
nerve injuries are combined with injury to other anatomical
structures. Months of therapy may be required to reestablish joint
and tendon motion before a splint/orthosis for the peripheral nerve
muscle imbalance is required. As motor power returns to the
muscle/s, the splint/orthosis is altered to maintain the best
balance possible for the remaining denervated muscles. (See figure
5).
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Figure 5. A patient with an injury to the ulnar nerve at the wrist exhibits the classic claw position. The small unobtrusive splint/orthosis prevents the denervated interosseous muscles from remaining in an over-stretched position, prevents proximal interphalangeal joint contractures, averts the development of muscle substitution patterns, and maximizes the functional use of the hand while awaiting nerve return. |
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The greatest challenge in reestablishing tissue glide and
functional sensory and motor regeneration is in patients who have
undergone replantation of an amputated part. Depending on the level
of amputation, remarkable functional results can be achieved with
months of individualized therapy, which includes numerous
splints/orthoses. Initially the splint/orthosis supports and
protects the healing tissue. As tissue healing progresses, the
splint/orthosis directs the tendon gliding, maintains soft tissue
length, or mobilizes stiff joints.
Splinting to Alleviate Joint Stiffness
One of the most common uses of the splints/orthoses is to regain
joint motion following injury and the subsequent joint stiffness.
Mobilization splints/orthoses are used to apply a gentle prolonged
force to effect tissue elongation. These mobilization
splints/orthoses can either be static splints that are remolded to
position the joint/s in a new position; static progressive splints
that allow the patient to adjust the position of the
splint/orthosis as the joint motion changes; or a dynamic
splint/orthosis that provides a continual elastic force.
Custom splints/orthoses can be constructed to increase joint
motion of any joint in the upper extremity in any plane of motion
desired. Exercises to strengthening muscles and reestablish maximum
tendon glide must accompany the use of any splinting/orthotic
program so passive motion gained by the splint/orthosis can be
maintained by the patient.
Splinting to Support an Unstable Joint
A supportive immobilization splint/orthosis may be used to
protect a healing ligament following injury and/or surgical repair.
This splint/orthosis is worn until healing is complete. The patient
is weaned from the splint/orthosis as physical activity is
increased.
Arthritis or trauma can diminish the normal joint stability
provided by the ligaments. In such circumstances, the patient may
require an external device to support the joint when muscle force
is transmitted across the joint during functional use. (See figure
6). If the patient is not a surgical candidate, or has multiple
other joints involved, the splint/orthosis may be worn indefinitely
and replaced many times.
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Figure 6. This patient with long standing rheumatoid arthritis has developed an unstable wrist joint, making it difficult to transmit force to her fingers. A custom molded splint/orthosis with a dorsal neoprene strap provides support to the wrist to maximize hand use. |
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Conclusion
Splints/orthoses made of low-temperature thermoplastic materials
can be fitted directly to the patient and easily changed. They have
become an integral part of the therapy process when regaining
motion or function in the hand. Each splint/orthosis has a specific
goal and, as the therapeutic goal/s change, the design and/or use
of the orthosis evolves. Although many splints/orthoses may be worn
long term, many are also worn only during the
post-injury/post-surgical period. Examples are shown which
introduce the reader to a variety of low-temperature thermoplastic
splints/orthoses. Judy C. Colditz is a licensed occupational therapist, certified hand therapist, and a Fellow in the American Occupational Therapy Association with more than 30 years of clinical experience in hand therapy. She has written numerous articles, chapters, and papers on hand splinting and therapy as well as co-authored the CD-ROM: The Interactive Hand-Therapist’s Edition along with an accompanying home study-guide published by the American Occupational Therapy Association. In the last five years, Ms. Colditz has been a three-time recipient of the best clinical paper award at the American Society of Hand Therapists Annual Meeting. She has taught courses, workshops, and lectures throughout the United States and Canada and in 24 countries outside North America. Contact: JColditz@HandLab.com
References
Benaglia P, Sartorio F, Franchignoni F. A new thermoplastic splint for proximal interphalangeal joint flexion contractures. J Sports Med Phys Fitness 1999;39:249-52. Colditz JC. The biomechanics of a thumb CMC immobilization splint: design and fitting. Jour of Hand Ther 2000;13:228-35. Van Lede P, Van Veldhoven G. Therapeutic hand splints—A rational approach. Volume I: Mechanical and biomechanical considerations. Antwerp, Belgium: Provan bvba; 1998. Van Lede P, Van Veldhoven G. Therapeutic hand splints—A rational approach. Volume II: Practical applications. Knokke-Heist, Belgium: Provan bvba; 2004. Wilton J. Hand splinting. London: W.B. Saunders Company, Ltd.; 1997. Coppard BM, Lohman H. Introduction to splinting-A clinical-reasoning & problem-solving approach. Second edition ed. St. Louis: Mosby; 2001. Hogan L, Uditsky T. Pediatric splinting-selection, fabrication, and clinical application of upper extremity splints. San Antonio, Texas: Therapy Skill Builders; 1998. McKee P, Morgan L. Orthotics in rehabilitation. Philadelphia: F.A. Davis Company; 1998. Jacobs ML, Austin N. Splinting the hand and upper extremity: principles and process. Baltimore: Lippincott Williams & Wilkins; 2003. American Society of Hand Therapists: Position statement on the use of orthotics in hand therapy. June 2003. Fess EE. A history of splinting: To understand the present, view the past. J Hand Ther 2002;15(2):97-132. Colditz JC. Therapist’s management of the stiff hand. In: Mackin EJ, Callahan A, Skirven T, Schneider LH, Osterman AL, editors. Rehabilitation of the hand and upper extremity. 5 ed. St. Louis: Mosby, Inc.; 2002. p. 1021-49. Akeson WH, Amiel D, Mechanic GL, Woo SLY, Harwood FL, Hamer ML. Collagen cross-linking alterations in joint contractures: changes in the reducible cross-links in periarticular connective tissue collagen after nine weeks of immobilization. Conn Tis Res 197 Akeson WH, Amiel D, Abel MF, Garfin SR, Woo SL-Y. Effects of immobilization on joints. Clin Ortho Rel Res 1987;219:28-37. Akeson WH. An experimental study of joint stiffness. J Bone Joint Surg 1961;43-A(7):1022-34. Amiel D, Woo SL-Y, Harwood FL, Akeson WH. The effect of immobilization on collagen turnover in connective tissue: A biochemical-biomechanical correlation. Acta Orthop Scand 1982;53:325-32. Woo SL-Y, Matthews P, Akeson WH, Amiel D, Convery FR. Connective tissue response to immobility: Correlative Study of biomechanical measurements of normal and immobilized rabbit knees. Arthritis and Rheu 1975;18(3):257-64. Arem AJ, Madden JW. Effects of stress on healing wounds: I. intermittent noncyclical tension. J Surg Res 1976;20:93-102. Pettengill KMS, van Strien G. Postoperative management of flexor tendon injuries. In: Mackin EJ, Callahan A, Skirven T, Schneider LH, Osterman AL, editors. Rehabilitation of the hand and upper extremity. 5 ed. St. Louis: Mosby, Inc.; 2002. p. 431-56. Colditz JC. Splinting the hand with a peripheral nerve injury. In: Mackin EJ, Callahan A, Skirven T, Schneider LH, Osterman AL, editors. Rehabilitation of the hand and upper extremity. 5th ed. St. Louis: Mosby; 2002. p. 622-34. 
Table Of Contents - October 2004
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