Description of Intervention1-4
The two primary flexor tendons of the hand are the flexor digitorum profundus (FDP), which is a flexor of the distal interphalangeal (DIP) joint that also assists with proximal interphalangeal (PIP) and metacarpophalangeal (MP) flexion, and the flexor digitorum superficialis (FDS), which is a flexor of the PIP joint that also assists with MP flexion. Other flexor tendons in this region are the flexor pollicis longus, flexor carpi radialis, and flexor ulnaris, but these tendons are primarily involved in wrist flexion. Injuries to the FDP and FDS tendons are among the most common hand injuries and typically occur secondary to lacerations or other forms of trauma. Flexor tendon injuries are divided into five zones (zones I–V), each of which carries a unique prognostic implication; however, most flexor tendon injuries require surgery followed by a period of either static or dynamic immobilization. 1-4
Static splints provide support and immobilization with no moving parts, while dynamic splints feature traction devices like rubber bands, springs, cords, or Velcro straps to allow for some range of motion (ROM) in the splinted joints. Dynamic splints are often preferred over static splints because they enhance the healing process of the repaired tendon through early active rehabilitation. In particular, the Kleinert splint is a dynamic splinting technique in which a rubber band is attached between the fingernail of the affected finger and the wrist to keep the finger in flexion. While wearing the Kleinert splint, the patient actively extends the finger against the band’s resistance and then relaxes it, which provides excursion at the tendon repair site without causing tension at the suture line. This splint also inhibits contraction of flexor muscles by reinforcing the normal reciprocal agonist-antagonist reflex mechanism.
Therefore, many hand therapists, both Occupational and Physical Therapists recommend dynamic splints for patients recovering from flexor tendon injuries that are surgically repaired. Flexor tendon protocols require splint wear for 5-6 weeks.
Indications for Intervention
A dynamic splint is indicated for patients recovering from surgical repair of a flexor tendon injury.
Evaluation
- Ask the patient to describe their medical history, with a focus on the event that led to the flexor tendon injury and the surgical procedure 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.
- Observe resting posture of the hand and assess the digital cascade.
- Assess skin integrity to help localize potential sites of tendon injury.
- 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.5,6
Orthoses Guidelines1-5,7-9
For a patient recovering from flexor tendon surgery that is a good candidate for a dynamic splint, you may choose from either a 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 adjust the dynamic components depending on which joints should be free to move
- 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 recovering from extensor tendon repair, but there are a few prefabricated dynamic splints available, which may be sufficient for some patients. Dynamic splints can be constructed with a variety of materials, including plaster, fiberglass, padding, ace wraps, metal, cloth, plastic, or leather. If fitting or 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.
Dynamic splints are usually applied within one week after surgery. The configuration and splinting position for each joint depends on the location and severity of the injury and type of surgical repair performed. The Kleinert splint involves attaching a rubber band from the fingernail to the wrist to place the wrist in full flexion <20°, MP joints in 20° flexion, and IP joints in full extension. A modified version of the Kleinert splint involves applying a pulley across the palmar creases with prolene underneath attached to a rubber band to place the wrist in full flexion <20°, MP joints in 90° flexion, and IP joints in full extension. Other variations keep the wrist in 20–30° flexion and IP joints in full extension but place the MP joints at 50–70° flexion. A static splint may be worn at night during this period to give the joints a rest.
After the splint is applied, the patient should be instructed to perform ROM exercises several times per hour, such as MP joint passive flexion and active extension exercises and IP joint flexion/extension exercises. At about 2–3 weeks after surgery, patients may begin to perform active wrist flexion/extension exercises and active extrinsic exercises out of the splint. The therapist should assess the patient at least once per week to adjust the level of tension and ensure that proper activity is being maintained. Dynamic splinting is typically discontinued at 4–6 weeks postsurgically, at which point the patient is to continue performing wrist flexion/extension exercises while adding strengthening exercises and passive flexion exercises for the MP joints and flexor tendons. Grip strengthening exercises may commence at 6-8 weeks, and the patient has been missing work, he or she may return to work at 10–12 weeks postsurgically. Edema and scar management are also essential throughout the entire rehabilitation program.
