S that will permit necessary functional use but prevent most of the persistent

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1 CURRENT COMMENT Orthetic Devices to Prevent Deformities of the Hand in Rheumatoid Arthritis By ROBERT L. BENNETT IMPLE ORTHETIC DEVICES can be made for the fingers and thumb S that will permit necessary functional use but prevent most of the persistent positions of fault that could lead to structural deformity. It therefore seems reasonable to believe that if these devices can be fitted at the earliest signs of persistent faulty alinement in arthritic joints, and if the patient will wear these devices, functionally dangerous deformities can be avoid-ed, or significantly controlled. Most of us have long used rest splints for the control of pain and deformity, and corrective splints to overcome or retard deformity. While these are orthetic devices of proven value, most of them are heavy, cumbersome, and poorly adapted to the functional requirements of the hand. For the past several years, we have attempted to develop orthetic devices that could be used during both daily activity and nightly rest. To prevent deformity, such devices would be prescribed as part of a total program to retain joint mobility and muscle strength. The devices would be indicated as soon as the earliest deviations from normal alinement were noted. A device to prevent deformity in an involved, but still mobile and responsible joint, must permit the normal planes of motion necessary for essential function, but block all faulty planes that might result in functionally significant deformity. Such a device must also have certain attributes before the patient will consent to wear it as it must be worn; both day and night. First, it must be comfortable and light in weight. Second, it must be acceptable in appearance, stay in place during use, but slip on and off easily when desired, Third, it must be durable, and if at all possible, have no buckles, straps, clips, buttons, adhesive tape, or other holding devices that stretch, break, smell offensively, or deteriorate in any way. These are the goals that we set for ourselves in the design, fabrication, and fitting of preventive devices. We are quite willing to admit that some patients would not wear splints even if they were invisible, weightless, and cost nothing. Assuming that we could achieve the above objectives-the reasonable ones-what is the rationale for considering the use of such a device in the first place? For all practical purposes, a major factor-perhaps the major factor-in the pathogenesis of musculoskeletal deformities in arthritis may be simply stated: persistent faulty positioning of joint structures during rest or activity. The immediate causes of this faulty positioning may be pain, or muscle spasm which, if uncontrolled, cause eventual freezing of the joint ROBERT L. BENNETT, M.D. : Executive Director, Georgia Warm Springs Foundation, Warm Springs, Georgia ARTHRITIS AND RHEUMATISM, VOL. 8, No. 5 (OCTOBER), 1965

2 ORTHETIC DEVICES TO PREVENT DEFORMITIES 1007 by contracture of periarticular ligamentous tissue and of intrinsic and extrinsic muscular tissue. This is particularly true in such joints as ankle, knee, wrist, and elbow. In the hand, the causes are more likely to be kinesiologic; that is, the demands of occupation or other habitual stresses that repeatedly force the fingers and thumb into positions of eventual deformity. Most of these stresses are quite obvious-the simple mechanics of pinch, for example-but others are more subtle and evade precise analysis at this time. However, faulty functional patterns of themselves are not likely to cause significant structural deformity in hands with normal bone and joint tissue. In rheumatoid arthritis two changes may take place in bone and joint to permit kinesiologic faults that cause and aggravate structural deformity. These two changes must be appreciated before the type of preventive splinting that we will discuss can be appreciated. The first change appears to be a loss of the normal resiliency of periarticular tissue. This loss of tissue integrity results in failure to correctly position the joint during the static pressures of rest, and the static or dynamic pressures of function. It is the responsibility of periarticular tissue, as well as intrinsic muscular tissue about the joint, to properly set the articular surfaces of the joint during static pressure (pinch, grasp, etc.), and to properly track the articular surfaces during dynamic movement. While the intrinsic muscles contribute to fine and precise movement, their major purpose is to hold the skeletal structures making up the joint in proper position so that the powerful extrinsic muscles can exert safe and effective pressure or movement. I have come to believe from watching rheumatoid joints deform that the primary mechanical fault is the change in supportive ligamentous tissue, and that muscular weakness is secondary to misuse ( overwork, or disuse; overstretching, or adaptive shortening), as well as to the chronic inflammatory changes in the collagen matrix of muscle. The second change is the faulty grooving of subchondral bone underlying degenerating articular cartilage. As the articular cartilage is eroded and destroyed, the fibrogenic and osteogenic subchondral tissues must be packed or compressed into a contoured plate resembling the normal articular surface. If this can be done and the periarticular tissue and intrinsic muscular tissue have been kept intact, the rheumatoid patient can retain effective range of motion and stability. On the other hand, if the bone ends are under persistent faulty compressive, shearing, or torsional stresses, the ultimate articular surface is distorted and cannot move effectively, nor stabilize effectively. All this adds up to the need for orthetic devices so designed that they permit normal use of joints but prevent all faulty use that might result in deformity. It is within reason to assume that this can be done in many, but perhaps not all, joints. It should be re-emphasized that we cannot expect a patient to wear a device to prevent a deformity that he does not have, unless he is first convinced that he will develop the deformity if he does not wear the splint. Second, he will not wear a device unless that device has all the attributes of comfort, etc., that were mentioned above.

3 1008 ROBERT L. BENNETT Fig. 1.-Medial instability of interphalangeal joint of thumb. Let US now discuss five deformities of the fingers and thumb, and the possibility of their control by means of early use of specially designed ortheses. Of the many possible skeletal deformities in the hand, these five have been selected because they occur commonly and are of great functional significance. The devices to control these deformities were developed at Warm Springs over the past several years upon patient demand. Only recently have we set up a specific orthetic research project in Rheumatology. Each of these devices can be improved-and we are working to this end. Our hope is that some of you can see their value and begin using them on your patients. These devices cannot be mass produced; they must be fitted by a real craftsman. They usually have to be modified several times before they are comfortable. However, the design and fabrication can be precisely described, and primary points in fitting can be clearly outlined. If any interest is shown in these devices, a pamphlet can be written for the orthotist as well as the physician. 1. DEFORMITY: Medial instability of interphalangeal joint of thumb (fig. 1). (a) Description: When this deformity is present, the distal phalanx of the thumb can be moved laterally with no restraint from collateral ligaments. This is particularly true in extension, but also develops in flexion as well. Eventually this terminal phalanx becomes completely unstable and can be moved in all directions without restraint. (b) Significance: This deformity results in inadequate and painful pinch. (c) Pathogenesis: This appears to be primarily a kinesiologic deformity caused by the forces required to press the anteromedial pad of the thumb against the fingers or against objects being pinched or held firmly between the thumb and long fingers. (d) Devices in Use: Presently used is a simple two-ring slip-on device to hold the interphalangeal joint rigidly (fig. 2). This is made of aluminum.* *All the aluminum devices that we discuss are first formed and fitted, then anodized. Anodizing prevents oxidation that discolors the skin. A pale gold anodized finish is almost skin tone and is the choice of most patients.

4 ORTHETIC DEVICES TO PREVENT DEFORMITIES 1009 Fig. 2.-Slip-on device to control medial instability of interphalangeal joint. Fig. 3.-Experimental slip-on device to control instability of thumb. This splint can be used easily over the burnt out degenerated joint, but is difficult to fit comfortably over the inflamed and swollen joint. As a preventive splint its great fault is that it limits flexion of the interphalangeal joint. (e) Dezjices in Deuelopment: A much lighter slip-on device that supports the interphalangeal joint medially and laterally and permits flexion is now being evaluated (fig. 3). This is slipped over the interphalangeal joint and is then rotated into snug position behind the joint so that it does not cause painful pressure. When fitted correctly it spans the joint without pressing on it. It may be made of plastic, but plastic-in our experience-cannot be molded to comfort as easily as metal. 2. DEFORMITY: Flexion of metacarpophalangeal joint and hyperextension of interphalangeal joint of thumb (fig. 4).

5 1010 ROBERT L. BENNETT Fig. 4.-Flexion of thumb. of metacarpal joint and hyperextension of interphalangeal joint Fig. 5.--Strap-held device to extend metacarpal joint of thumb and promote flexion of interphalangeal joint. (a) Description: This deformity consists of the dual fault of flexion contracture of the metacarpophaiangea1 joint and extension contractme of the interphalangeal joint of the thumb. (b) Significance: This deformity results in inadequate pinch. (c) Pathogenesis: This appears to be a kinesiologic deformity due to faiiure of positional restraints during stress of pinch or other pressures against the

6 ORTHETIC DEVICES TO PREVENT DEFORMITIES 1011 Fig. 6.-Experimental device to control flexion of metacarpal joint and hyperextension of interphalangeal joint of thumb. pad of the thumb. Adaptive changes in the periarticular tissue and in articular surfaces result in the contractures. (d) Devices in Use: We have been using an aluminum or plastic slip-on device with a Velcro strap at the wrist to hold it in place (fig. 5). This device statically holds the metacarpophalangeal joint in extension, and requires flexion of the interphalangeal joint when the thumb is used. This present device limits thumb function, but its basic objection is the need for a strap around the wrist. (e) Devices in Development: A much simpler slip-on device has been made that controls flexion of the metacarpophalangeal joint, and prevents hyperextension of the interphalangeal joint when the thumb is used in pinch or grasp (fig. 6). It is slipped on the thumb and rotated into position, staying in place by lateral pressure against the flare of the distal end of the proximal phalanx, and can be fitted with little pressure on painful joints. 3. DEFORMITY: Hyperextension of proximal interphalangeal joint of fingers (fig. 7). (a) Description: During the initial stage of development this deformity is characterized by excessive hyperextensibility of the proximal interphalangeal joint, usually beginning in the ring or long fingers. Later, flexion of the joint diminishes and rigid contracture and hyperextension takes place. (b) Significance: This deformity causes marked limitation of function of fingers in pinch and grasp. (c) Pathogenesis: Functional positions of the hand do not appear to be causative in this deformity unless there is definite flexion contracture of the metacarpophalangeal joint. Rather, this appears to be due almost entirely to relaxation of the volar ligament which allows the interphalangeal joint to bow into hyperextension from the pull of the lumbrical on the extensor expansion. This extends the middle phalanx, and the pull of the interosseus flexes the

7 1012 ROBERT L. BENNETT Fig. 7.-Hyperextension of proximal interphalangeal joints of finger. Fig. B.-Slip-on joints. rings to control hyperextension of proximal interphalangeal proximal phalanx. When the metacarpophalangeal joints are held in flexion by either contracture or pain, positional stress on the proximal interphalangeal joint may be a factor in the development of this deformity. (d) Devices in Use: Simple double ring devices have been used at Warm Springs for many years (in neuromuscular disease as well as in arthritis) (fig. 8). The metal strip joining the rings can be bent to provide any position desired in the mobile joint and to help overcome limitation of flexion or extension. They can also be used to combat varus or ulnar drift of the middle phalanx. These rings must be fitted loosely so they can easily be applied and removed, but must fit snugly enough so they do not fall off. The rings can be slit to permit adjustment in fit. Their greatest disadvantages are that they are difficult to fit over swollen painful joints and they restrict function by limiting flexion.

8 ORTHETIC DEVICES TO PREVENT DEFORMITIES 1013 Fig. 9.-New joint. type slip-on device to control hyperextension of interphalangeal Fig. 10.-Ulnar deviation of fingers. (e) Devices in Development: A modified double ring device has been designed and used extensively in normal joints with no discomfort and very little limitation of useful function (fig. 9). These do not press against the joint and can be rotated into position. 4. DEFORMITY: Ulnar drift of index finger (fig. 10). (a) Description: This deformity is characterized by adduction of the proximal phalanx of the index finger. As this deformity progresses, anterior

9 1014 ROBERT L. BENNETT Fig. 11.-Splint fingers. with adjustable hinged half-rings to control ulnar drift of subluxation of the base of the proximal phalanx under the head of the metacarpal takes place. (b) Significance: This deformity is both functionally and cosmetically important. Precise and strong pinch and grasp is markediy limited. The drift of the index finger may be a dominant influence in the drift of the other fingers and control of the index finger might be enough to prevent deviation in the other fingers. (c) Pathogenesis: This deformity appears to be due primarily to the affect of muscular forces on relaxed ligamentous tissues supporting the metacarpophalangeal joint. The pull of the extrinsic flexors and extensors is medial to the vertical line of the second metacarpal and the proximal phalanx. The first dorsal interosseus and the first lumbrical must have strong assistance from the collateral ligaments of the metacarpophalangeal joint to retain normal joint position. (d) Decices in Use: In the past we have used a modified opponens splint with adjustable, medially placed hinged half rings against the proximal phalanges (fig. 11). This is expensive, cumbersome, and difficult to mold comfortably. More recently we have used a simple slip-on device that prevents adduction of the index, or of the index and long fingers (figs. 12 and 13). This is comfortable but limits flexion of the metacarpophalangeal joint. (e) Devices in Development: A simple change in design permits flexion while limiting adduction of the metacarpophalangeal joint (fig. 14). This splint permits free flexion, and does not press on the metacarpal joint, but it does not control the possibility of subluxation of the phalanx as does the older device and may therefore be less desirable. 5. DEFORMITY: Ulnar drift of the little finger (fig. 15). { a) Description: This deformity is characterized by excessive abduction of

10 ORTHETIC DEVICES TO PREVENT DEFORMITIES 1015 Fig Slip-on device to control ulnar drift of index finger. Fig Slip-on splint to control ulnar drift of index and long fingers, the fifth proximal phalanx. This may progress to severe anterolateral dislocation of the phalanx around the head and down the shaft of the fifth metacarpal. (b ) Significmces: While this deformity is both functionally and cosmetically important, its major importance may well be that it permits easy ulnar deviation of the other three fingers. (c) Pathogenesis: This deformity appears to be due primarily to the effect of intrinsic muscular forces on incompetent periarticular ligaments about the fifth metacarpophalangeal joint. Certainly the fourth lumbrical is no match for the much stronger abductor minimi digiti and flexor brevis. It appears that the pull of the extrinsic flexors and extensors would be a deforming factor only

11 1016 ROBERT L. BENNETT Fig. 14.-Experiniental device to control ulnar drift of index finger. Fig. 15.-Ulnar drift of fingers. after the phalanx has been pulled into excessive abduction by the abductor minimi digiti and flexor brevis. (d) Devices in Use: We have long used the cumbersome splint described in Deformity 4 to also control the little finger. For the past several years we have been using a slip-on device of aluminum with Velcro strap to hold it in place (fig. 16). This holds the little finger in good position but has the disadvantage of a strap that soils, and deteriorates.

12 ORTHETIC DEVICES TO PREVENT DEFORMITIES 1017 Fig Strap-held device to control ulnar drift of little finger. Fig. 17.-Experimental slip-on device to control ulnar drift of little finger. (e) Devices in Development: Several types of simple slip-on devices that hold in place well without straps have been developed (fig. 17). CONCLUSION Five common deformities were discussed and the devices to control these deformities described. Several other deformities of the hand can be controlled by simple adaption of these designs. Obviously, these devices must be oniy a part of an overall program to relieve pain, maintain muscle strength, and control the activity of the rheumatoid process. Without such a program these devices are of no value.

13 1018 ROBERT L. BENNETT We cannot hope to develop the ideal device until we know far more about the patho-kinesiology of joint dysfunction. It is difficult at this time to visualize the dsign of simple functional devices to control such deformities as flexion contractures of the metacarpal or interphalangeal joints of the fingers. All we can do at this moment is to splint these joints in extension and remove the splint frequently for mobilization. We are now working on a simple device to control the deformity of the thumb characterized by adduction, extension, and external rotation of the metacarpal. We think this can be done without interfering with function to any extent. These devices, despite their simple appearance, are not easy to make. If sufficient interest is shown in the use of these devices, we can write up the specifications for prescription, fabrication, and fitting of those we are now working with. One final word (the reader need go no further if he is adverse to preaching) the caliber of orthetics in any community reflects the knowledge and demands of the physicians in that community. The orthotist is a craftsman, not a doctor. He must not be expected to know what the patient needs, but he must know how to fill a precisely written prescription. If we want good orthetics, we must first know good orthetics and then demand good orthetics. To those who would say, We can t get these devices, or, They are too expensive, my only answer is: surgeons no longer use the kitchen table and a butcher knife in elective surgery.