Description of Intervention1-5
Hand therapists often request for the hand surgeon to prescribe dynamic splints to restore the passive range of motion (ROM) of one or more stiff joints. These orthoses utilize traction devices like rubber bands, springs, cords, and/or Velcro strips to hold the stiff joint(s) at the end of their available ROM under light tension for intermittent periods. Applying this prolonged, low-load stretch to joints provides a stimulus for collagen growth and reorganization, which will eventually facilitate the return of the joint’s passive ROM and directly effect AROM & functional improvements.
Dynamic splinting is therefore indicated for flexion contracture of the metacarpophalangeal (MP) joints to increase MP extension. Extension contractures are more common than flexion contractures in the MP joints, in part because the metacarpal head has a trapezoidal shape, and its collateral ligaments have an eccentrically dorsal origin to the axis of rotation. This creates a cam effect as the proximal phalanx is flexed and the collaterals are stretched, and MP joint flexion tightens the collateral ligaments. In extension, the collateral ligaments are lax, so MP joints that remain extended become stiff as the lax ligaments contract.
Nonetheless, MP flexion contracture does occur secondary to certain traumatic injuries, including severe or comminuted fractures and burns. In fact, the MP joints are affected by burns more frequently than the proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints. Although used less commonly, dynamic splinting can be applied to the MP joints in a similar fashion to the dynamic splinting applied to DIP and PIP joints. Doing so appropriately and in a timely manner can help patients by lengthening shortened soft tissues, increasing ROM, providing resistance to weak contractile tissues, preventing imbalances and tendon adhesions, decreasing edema, and restoring function to involved MP joints.
Indications for Intervention
A dynamic splint for MP extension is indicated for patients with flexion contracture in one or more MP joints.
Evaluation
- Ask the patient to describe their medical history, with a focus on the injury to the digit(s) and if any surgical procedure was performed.
- Ask if the patient has any comorbidities, including diabetes, osteopenia/osteoporosis, cardiovascular issues, or a history of smoking.
- Perform a physical examination of the hand and wrist. Measure the active and passive ROM of the joints involved and compare these values with those of the contralateral side.
- Ask the patient to rate their pain on the visual analogue scale (VAS) or a similar pain scale.
- Consider using the Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire, which is used to assess impairment of the upper extremity.
- Other parameters that may be evaluated include task performance with a hand function test, power grip with a hand dynamometer, pinch grip with a hydraulic pinch gauge, and dexterity with a pegboard.6,7
- If flexion contracture is identified in one or more MP joints, consider prescribing a dynamic splint for MP extension.
Orthoses Guidelines1-6,8,9
When a dynamic splint for MP extension is indicated, you may choose to prescribe either a prefabricated, custom-fitted, or custom-fabricated splint:
- Prefabricated splint: these splints are made by a manufacturer and can be purchased over the counter at pharmacies or with a prescription from orthopedic supply stores; therefore, prefabricated splints are not individualized for the patient and do not require any special fitting services; however, patients can make minimal adjustments with Velcro straps to ensure the splint fits properly, and the therapist will also adjust the dynamic components of the splint depending on the specific indication
- Custom-fitted splint: this is a type of prefabricated splint that requires bending, cutting, or molding the splint to fit the patient’s hand properly; it may be necessary to apply heat to manipulate the splint
- Custom-fabricated splint: these splints are individualized for each patient by taking castings, measurements, tracings, and images of the injured area that are used to create a specialized splint; you will then fabricate the splint by molding, drilling, sewing, or bending the splint material before fitting and applying it to the patient
Custom-fitted and custom-fabricated splints are strongly recommended for most patients requiring a dynamic splint for MP extension. Dynamic splints can be constructed with a variety of materials, including plaster, fiberglass, padding, ace wraps, metal, cloth, leather, or thermoplastic. Traction devices like rubber bands, springs, cords, or Velcro strips are then added to the orthotic to apply a passive extension force to the MP joint(s) involved. When fabricating the splint, ensure that it fits comfortably. The splint should also allow for maximal sensory perception, and the pressure of the splint should be distributed equally. It should not challenge the normal contours of the hand and forearm. Pain medications may be needed before and during the splinting process.
The configuration and splinting position for each joint depends on the location and severity of the injury and, if applicable, the surgical procedure performed. When fabricating a dynamic splint for the MP joint(s), all finger joints—MP, PIP, and DIP joints—are left free and the traction device is attached to the MP joint(s) involved. One popular design that may be used is an outrigger splint with rubber bands for traction, which can be fabricated with thermoplastic material, rivets, wire frame, hoop-and-loop Velcro strips, rubber bands, finger slings, and Theraband straps. A gauge should be used to determine the amount of dynamic force applied, with 100–150 g/cm2 often being a good starting point. The force magnitude can then be adjusted based on the patient’s response to the splint.
When fabricating a splint for fractures, ensure the splint design minimizes valgus and varus stresses to optimize the alignment of the fracture fragments and promote a physiologic arc of motion of the involved finger(s).
The duration and frequency for wearing the splint is also largely dependent on patient variables. For the outrigger splint described above, patients should wear the splint for 8–12 hours daily for 8 weeks, primarily while sleeping and for several hours while awake. For burn patients, only 3 hours per day may be tolerated at first. Daily use should increase gradually based on patient tolerance. After about 8 weeks, patients can be weaned off the splint over the following 2–3 weeks, although longer periods may be required for some patients. When the splint is not being worn, patients should perform active flexion and extension exercises for the fingers every day to reduce the risk for tightening and shortening of the tissues. Static splinting should be integrated for night/sleeping to ensure no undo forces are placed on the tissues at rest/sleep. It’s very important for the hand therapist and hand surgeon to collaborate and emphasize the importance of patient involvement in the rehabilitation process.
Splint use must be supplemented by a comprehensive hand therapy treatment program, with sessions at least once per week. The basis of hand therapy rehabilitation programs is passive and active ROM exercises, and the therapist should check the biomechanics and tension of the splint at each visit and adjust these parameters if necessary. Advise patients to slowly return to activities as they regain their hand and finger function. Edema and scar management—when applicable—are also essential throughout the entire rehabilitation program.
