A Dynamic Brace for Finger-Joint Reconstruction in Arthritis
Alfred B. Swanson, M.D., F.A.C.S.
The advent of flexible implants for internal stabilization of finger-joint arthroplasties has opened up new possibilities for successful reconstructive surgery of the hand8,10,12. A dynamic brace has been developed to facilitate early postoperative motion in these cases11,12. Its use has greatly improved the anatomical and functional results.
The requirements for a successful arthroplasty are stability, mobility, and freedom from pain. In well-done resection arthroplasties, sufficient soft tissue releases must be done to correct the frequently associated contracture, subluxation, or angulation deformities1. After adequate release, the joint is unstable in the early postoperative period. Internal fixation with wires has usually been necessary to maintain the restored anatomy4. Thus early motion has not been possible. Since the preoperative dislocation or angulation tends to recur, mobility must be sacrificed to stability.
Through the use of flexible heat-molded silicone rubber implants as an adjunct to resection arthroplasty the concept of early motion can be fulfilled. The implant acts as an internal splint that separates incongruous bone ends, decreases the tendency toward recurrent subluxation, and provides a mold for the development of a new joint capsule. Once the released ligaments and the scar have healed, they will stabilize the joint in a fashion similar to normal ligaments13.
As with simple resection arthroplasty, restrictions of motion during this healing phase will result in poor mobility. Controlled motion during this period will cause the new capsule to have sufficient looseness for flexion and extension, but have adequate tightness in the mediolateral plane for rotational and angular stability. Therefore an adjustable dynamic brace is necessary to encourage the joint to move in desired planes and to prevent recurrences of deformity during the early postoperative course. The brace should also prevent undue stretching of associated reconstructed tendons and ligaments. It will also assist the extensors and flexors of the digits, which are frequently weak because of the long-standing deformity which accompanies tenosynovitis and fibrosis. The dynamic brace has three major functions:
to provide complete and adjustable correction of residual deformity
to control motion in the desired range
to assist flexor and extensor power in insuring an adequate alternation of complete extension and flexion ranges of joint movement.
The basic brace is a dorsal splint which provides a stable base for outriggers and support for the weak or deficient wrist joint2,3,5,6,9. A transverse bar to which finger slings are attached is fitted onto the dorsal arm. The slings are of a soft plastic with multiple perforations and are connected to the bar by rubber bands (Fig. 1 , Fig. 2 , Fig. 3 , and Fig. 4 ). Small radially placed outriggers may be added for correction of the pronation deformity often present in the index and middle fingers (Fig. 5 ). A longer bar can be used to increase thumb abduction. All of these outriggers are attached with thumb screws. The position of the transverse bar can be adjusted in all three planes.
When weakness of the flexors is present, a flexion cuff is used to insure that the joint is carried through an adequate range of motion (Fig. 6 ). This sheepskin cuff is attached to the dorsal molds and around the digits, and is drawn into flexion by a Velcro strap run through a loop on the proximal portion of the brace. With this cuff, the finger joints can be passively brought into flexion for desired periods of time during the day. An elbow strap is used to prevent distal migration of the brace when the cuff is used. The brace is held in position with two adjustable Velcro straps on the forearm and a narrow Velcro strap across the palm. A palmar pad is used to help maintain the arches of the hand and to prevent rotation of the brace.
The brace is available in three basic sizes from the Pope Brace Foundation, Kankakee, Ill. The brace should be obtained before surgery, so that it can be applied on the third to fifth postoperative day. The voluminous operative pressure dressing is removed and a light padding is applied to the hand, wrist, and forearm. Small dressings may be applied to individual digit wounds. The metal portions of the straps are relatively flexible and can be easily adapted to the patient's size. The brace is adjusted so that the rubber-band loops hold the fingers in distal extension and slight radial deviation. If there is a tendency toward pronation of the index and middle fingers, extra loops are applied laterally to the distal phalanx. A supinatory rotation can be achieved in this manner. The tension of the rubber bands should not be so great that the patient cannot accomplish flexion. This is especially true with regard to the fifth digit. The patient is encouraged to flex and extend his digits frequently within his fatigue and pain tolerance. He is also asked to elevate the extremity and move the elbow and shoulder. The brace may require adjustment once or twice a day in the early postoperative course.
The extension portion of the brace is worn continuously for the first week. In the second postoperative week, the patient is allowed to remove the rubber bands in order to achieve greater flexion of the MP joints. This removal is usually allowed for one to two hours twice a day. A range of motion from 0 deg. to 70 deg. of flexion is the goal. If the patient does not appear to be obtaining 70 deg. of flexion, the flexion cuff is worn for one to two hours twice a day. The extension portion of the brace is used continuously night and day for at least three weeks. The extension portion of the brace is then usually worn just at night for another three weeks. In a few cases, where there is a persistent extensor lag or a tendency toward deviation of the digits, continued support by the brace must be prescribed for several more weeks. A flexion cuff may also be applied during this period if it appears that the desired range of flexion is not being achieved. The range of motion should be measured with a goniometer and recorded for the evaluation of progress. The patient should have a prescribed exercise and stretching program for at least the first three months. By this time the ultimate range of motion that can be expected will usually have been reached. Collagen maturity and scar contraction differ from patient to patient7. The associated tendon deficiencies also vary. Therefore, use of the brace in the postoperative period requires the careful attention of the operating surgeon.
The brace is designed so that with a simple adjustment it can be used for either the right or left hand. It has also been modified so that it can be of value in a variety of additional conditions. A lumbrical bar is supplied for patients who need pre- or postoperative proximal interphalangeal (PIP) joint extension (Fig. 7 ). Care must be taken in the use of this device on patients who have had recent metacarpophalangeal (MP) joint arthroplasty, because in these cases the proximal phalanx will have a tendency to subluxate palmarwards on the metacarpal if too much force is applied. The brace has also been used for patients who have undergone proximal interphalangeal joint arthroplasties. By supporting the proximal phalanx with the slings, selective PIP joint active motion is encouraged. The flexion cuff can also be applied as an assist in improving the flexion of the proximal interphalangeal joints. The brace has also been used after simple synovectomy of the finger joints in arthritis, and following release of contracted finger joints in traumatic injuries.
A dynamic brace developed in our research program at the Blodgett Memorial Hospital and used for the past six years is described. This brace has been used on more than 200 patients and has never been refused by a patient. It forms an extremely important adjunct in arthroplasty surgery of the digits. In our opinion, its use in the postoperative period is absolutely necessary if the full potential for functional restoration is to be achieved. It is versatile, adjustable, and allows the patient the freedom of motion which he desires and needs.
The kind assistance of A. Oostindie and B. Stegman, orthotists of the Mary Free Bed Brace Shop, in the development of this brace is gratefully acknowledged.
Chief, Orthopaedic Surgery and Orthopaedic Research Blodgett Memorial Hospital, Grand Rapids, Michigan
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