Pathomechanics: Inevitability of Gradualness
Contracted joints and soft tissues can be remodeled and contractures corrected through the serial application of plaster casts or orthoses that hold the shortened tissue or joint at the end of its available length or range of motion (ROM) for a prolonged period of time. Through serial reapplication of the plaster cast or orthosis the tissue gradually elongates, resulting in correction of joint and soft tissue contractures and/or muscle-tendon unit tightness.
Serial plaster orthotic positioning or casting for contracted joints or soft tissues began with Paul Brand in his use of plaster casting of clubfeet in children. He began to understand that the initial benefits of forceful correction with “wedge casting” were often undone by deep tissue scarring and later tissue contraction, and was sure that there must be a way of correcting a joint deformity without such damaging force on the tissues and on the child. Once Brand relocated from medical school in England to India, he observed there that adults with clubfeet that had never been corrected still had supple joints.
Under Brand’s direction, an infant with a clubfoot deformity was put to nursing while plaster of Paris was placed in single layers directly on the foot to be corrected. The foot was gradually moved into a corrective position while the plaster was setting until the child turned his or her eyes and “looked.” Correction of the foot always would stop before the point at which the child would begin to cry signaling distress. The foot would be held in this position gently but firmly, and the plaster allowed to set. Frequent successive recasting using the same procedure resulted in correction of the deformity—and a healthy joint! The method was so successful that the idea was applied to the interphalangeal (IP) joints of severely clawed hands found in patients with Hansen’s disease (leprosy) at The New Life Center established by Brand, in Vellore, India. The technique met with equal success in these patients, who were thought beyond hope from medical intervention. The technique has continued to be successful for any small or large contracted joint or soft tissue. It works to lengthen the skin and contracted soft tissue, including vessels and nerves , and muscle-tendon units, for single or multiple joints. Plaster’s conforming properties make it ideal for orthotic positioning, since it distributes forces throughout the length of the cast, eliminating points of pressure under the cast.
Growth Not Stretching
The serial casting/positioning technique described by Brand is not one of progressive “stretching” but of “growth of tissue.” Forceful stretching of soft tissue can cause tissue damage resulting in inflammation and later scar formation. The remodeling process, in contrast, takes time, thus the contracted joint or tissue must be held in a lengthened position for a period of time. The contracted tissues are stimulated to gradually elongate by being held at the maximum possible length. Each day or every other day, the cast or orthosis is removed and the joint or soft tissue can then be repositioned at a greater length. Through this serial casting or positioning method, the joint, soft tissue or muscle-tendon unit contracture may be gradually corrected over a period of days or weeks. In support of this approach, Eppenstein et al. documented research demonstrating that low-load, long-duration tension is optimal in reducing the risk of tearing soft tissue, increasing residual elongation, and providing more permanent realignment of collagen fibers into a more parallel orientation.
Steve Kolumban, a therapist working with Brand at the Christian Medical College and Hospital in Vellore, India, compared night orthotic positioning with regular physiotherapy technique in 24 outpatients with contractures of the IP joints. Regular physiotherapy consisted of wax baths, oil massage, and exercise (passive and active-assistive). At the end of the study the group with the orthotic positioning had significantly superior results. The percentage of degrees straightened from the total possible number was 45.7% with orthotic positioning and 0.9% without it. Of the 25 fingers in the group without orthotic positioning, 12 joints ended with a greater contracture than that with which they began .
Later Kolumban compared cylinder serial plaster casting with dynamic orthotic positioning. The study matched fingers from both groups into pairs of six variables: age, contracture angle, joint resiliency, length of the finger, length of orthotic positioning, and applied straightening force. A straightening force of 250 g was applied in both methods of positioning. At the end of the study the results showed a strong indication that the casting was superior to dynamic positioning. Of 26 patients with 52 contracted IP joints, the percentage of degrees straightened from the total possible with serial cylinder plaster casting was 47.8% and with dynamic orthotic positioning, 34.9%. Important to note is that there were no injuries to the involved tissues (many of the patients had anesthetic hands) resulting from the plaster casting, and there were seven injuries with dynamic orthotic positioning.
The technique was adopted by hand surgeons in England and used for joint and tendon contractures after war injuries. Brand brought the technique to the United States in the treatment of patients with Hansen’s disease when he relocated to the U.S. Public Health Service Hospital in Carville, Louisiana, and in his worldwide tours and lectures. Under his direction in 1973, I used the serial cylinder casting technique for IP joints of the hand, and adapted it to be removable at the New Orleans U.S. Public Health Service Hospital for seamen. In 1976, having relocated to the Center, I introduced the casting techniques to the Philadelphia Hand Center, Ltd., in Pennsylvania, for patients with a wide variety of conditions resulting in joint contractures of the hand. Conditions in which the casting has been used successfully to reduce finger contractures include arthritis, reflex sympathetic dystrophy, Dupuytren’s contracture, congenital contractures, joint dislocations, burns, boutonnière deformities, swan-neck deformities, and contractures after fractures and tendon repairs.
Brand and Kolumban, as well as Eppenstein et al., emphasized the importance of pre- and postcasting measurements, with fixed repeatable positions for measurement. If active and passive finger extension is recorded before casting with the wrist in neutral, the same position should be used postcasting. In assessing finger stiffness and contracture, Brand used passive controlled tension measurements with the wrist in flexion, neutral, and extension to differentiate joint tightness, versus muscle-tendon unit tightness. Before using serial casting or orthotic positioning, a therapist should determine the underlying cause of the limitation, whether joint contracture, muscle contracture, nerve injury, or spasticity.
Indications for Serial Plaster Casting or Orthotic Positioning
The use of serial plaster casting or orthotic positioning for progressive tissue remodeling works on large joints and on muscle-tendon units, and is particularly suited to small joint contractures, where other forms of positioning often fail. Most therapists know that if a full range of motion (ROM) can be achieved by active exercises alone, then there is no reason for an orthosis. A skilled therapist can use specific exercise and positioning, or teach the patient to use these to maintain or restore active movement and balance to the joints. For patients with mild contractures, often a simple augmentation to therapy using night orthoses or dynamic mobilization orthoses is all that is necessary. But for more significant contractures, serial plaster casting usually works better than other forms of orthotic positioning, because tension in the tissues is maintained over 24 hours to effect a change in length of the tissue.
Unless there is a bony block or joint dislocation, serial casting can be successful in the treatment of some old fixed deformities where other orthotic positioning is not. In fact, it is indicated when the use of dynamic traction fails. Dynamic mobilization orthotic positioning may come out of adjustment and has to be continually checked to ensure that traction is at the angle and the specific gram traction desired. Rubber bands used for traction fatigue quickly and must be changed frequently. Even with controlled slow traction, the tissues often will not tolerate enough traction to overcome long-standing contracture or recurrence of joint stiffness.
Advantages of Casting for Tissue Remodeling
Swelling is never increased by the plaster cast and is often decreased because the cast keeps the joint still for periods of rest. In contrast, dynamic mobilization orthotic positioning can cause an increase in swelling when the force is too high or the finger cuff or straps are too tight. Because casting does not forcefully stretch the tissue, pain is not increased by serial casting and is often decreased. This is particularly important in patients with complex regional pain syndrome, in whom even a slight increase in pain is a step in the wrong direction. Cylinder casting can be used over lacerations and ulcers. The technique has been found useful with insensitive fingers in particular, so that they can heal without further trauma. Plaster allows the skin underneath to breathe and does not macerate the skin if applied directly, and may be better tolerated than other positioning materials. The plaster allows some air to the wound and absorbs tissue exudates.
Used correctly, casting is a nontraumatic way of gaining additional flexion or extension range. Circulation of the finger is always checked after cast application to make sure the vascular supply is not compromised. The patient is always instructed to remove the cast later if it appears too tight, but this is rarely necessary.
Plaster of Paris (amorphous anhydride calcium sulfate) is readily available and cost-effective, making it adaptable to a variety of circumstances including hospital wards and intensive care units. When water is added to the plaster it can be conformed precisely to the target joint or tissue in the desired position. Once it hardens the plaster orthosis or cast maintains the position securely. Johnson & Johnson developed the Specialist Plaster Bandage , which is recommended due to its fast setting and ease of casting (Johnson & Johnson, Smith & Nephew Rolyan, and Carpace and Lohmann). The types of plaster of Paris used are fast-setting (5–8 minutes) and extra-fast-setting (2–4 minutes). Gypsona was used by Brand and still liked by many clinicians; however, its product literature warns against direct application to the skin due to heat produced during setting. The clinician needs to carefully read all product literature and follow instructions for safe use of any material.
One needs to be aware of the thermal effect of plaster during setting. The temperature of the water used for wetting the plaster should be cool, since hot water can increase temperature on setting of the plaster. Generally temperature peaks between 5 to 15 minutes after application. Heat produced is somewhat relative to the number of layers used, thus very thin layers can usually be applied directly to the skin. For finger casts, no more than one to two layers in what Brand called “eggshell casting” are needed. For wrist and forearm casts, six to eight layers, slightly padded, are usually sufficient. Strength can be improved by additional accordion-type folds or layers added specifically at the wrist or thumb. While allergic reactions are relatively rare, the clinician needs to be mindful of the possibility from plaster or any material placed in contact with the skin. During and after casting one should routinely monitor the skin for possible irritation.
Serial Cylindrical Casting
Serial cylinder casting can be used to increase joint ROM in either flexion or extension and is most commonly applied to the proximal IP (PIP) joint. Optimally the cast is changed every other day ( Fig. 125-1 ). It is important to mobilize joints briefly during cast changes. Paraffin wax or other thermal modalities can be used, followed by a brief session of manual exercise and mobilization before the cast is reapplied. It is expected that with each cast change the involved tissues or joint(s) can be positioned further in the desired direction of flexion or extension.
The method of application depends upon the joint being treated. Only two layers of plaster are needed for a finger joint if made circumferential, and one layer combined with a volar or dorsal orthosis in two stages. A single 1-inch strip of plaster about 1 foot long is all that is needed for most fingers. Padding is not used or is limited to a wisp of cotton over an area of concern of pressure. It is desirable that the plaster sticks slightly to the skin, as this keeps the skin from moving under the cast and causing shear, and distributes pressure along the length of the cast, rather than joint prominences.
Non-gypsona plaster of desired length is dipped in water (usually room temperature) and dried on a paper towel slightly. This will remove excess water, makes it easier to handle and wrap, and minimizes drip. The cast can be made all in one piece wrapped distally from the base to the tip of the finger, or in two pieces cut from the 1-inch-wide plaster in 12- to 15-inch lengths. Start with folding the gauze plaster edge that will first be in contact with the finger about the width of the finger ( Fig. 125-2 ). Begin wrapping from the base of the finger, in an overlapping fashion ( Fig. 125-3A and B ). Then reverse, fold the gauze plaster edge the width of a finger, and start the second wrapping from the tip of the finger to just beyond the level of the IP joint. In this way the last bit of cast material can often be placed just under the IP joint for a little extra support (while not making the cast too thick). If it is desirable to be able to remove the cast, the very tip of the cast can be left open. In either method, just before the strip of plaster is applied to the hand, a slight fold on the edge of the plaster strip will make a smooth rather than a rough edge against the finger web and volar distal edge of the cast. This slight fold can be made wherever there will be an edge to the cast.
The plaster is wrapped just proximal to the distal IP (DIP) joint crease if later DIP joint movement is desired, and it is wrapped past the DIP joint crease in the following cases:
The profundus tendon is tight when casting for extension.
The extensor mechanism is tight when casting for flexion.
The improvement in ROM is also desired at the DIP joint.
When the plaster starts to become warm it is beginning to set. At this point the plaster should not be moved, but allowed to set.
How to Assure Correction of the PIP Joint Position
While wrapping the cast, the joint or joints are moved gently into the corrected position. While the plaster sets, the position is held and the plaster smoothed with a continuous motion of the fingers, which helps to avoid pressure areas in the cast. The finger is supported in extension while wrapping if the cast is being used to increase extension, and in flexion while wrapping if the goal is to increase IP joint flexion. A useful technique after the cast is wrapped is to maintain a corrective tension on the joint as the cast sets. This is accomplished by stabilizing the metacarpophalangeal (MCP) joint in 90-degree flexion, while the other hand lightly pinches the tip of the finger being casted. In this way, one can effectively apply a distraction to straighten the PIP joint. This distraction is enough to gently elongate the finger ( Fig. 125-4 ).
How to Avoid Adding Force
If one applies force to the joint during casting, joint and skin irritation may result and potentially more joint stiffness. So it is better to start with only a very mild elongation of the tissue, and gently increase tension with successive casts once the tissue tolerance is determined.
Why Absent or Minimal Padding?
The most damaging force to skin is not from direct pressure but from shear force when the skin moves in a lateral direction relative to an edge or normal pressure. Plaster that is not padded will conform and adhere slightly to the skin, preventing shear force under the cast when the fingers are moved. Wounds are covered very lightly.
If irritation has developed over the IP joint, casting technique should be examined. A small, thin fluff of cotton may be placed over the dorsum of the joint before it is recasted, and this slightly relieves the cast in this area. Occasionally, when the dorsal skin over the IP joint is fragile, a small amount of padding is required for successful casting. For patients with fragile skin, small, thin fluffs of cotton also may be added at the distal and proximal volar edges of the cast when the finger is casted.
How Often to Change the Cast
The casting is most effective if it is left on continually and changed every other day. It must be changed at least twice a week and the joints exercised to maintain their full mobility. After exercise, a new cast can be applied in what will probably be a few degrees more in the desired direction of either flexion or extension. The casting procedure may be continued as long as improvement is noted, and discontinued when measurements plateau.
How to Remove a Cast Left on
Cylinder casts can easily be removed by immersing the hand in water, finding the edge, and unwrapping, or by squeezing the cast from side to side. Alternatively, the cast that has not been soaked can be cut along its dorsal surface with thin blunt-tipped scissors. Suture scissors or wire snips (with blunted tips) work well to remove the cast.