The purpose of a functional fracture brace is to provide fracture alignment stability but not rigid immobilization of the bone ends. It is the “controlled” motion within the fracture brace that is the desirable stimulus to healing.
Because functional fracture bracing stabilizes but does not immobilize fractures, it is used only in fractures with minimal displacement, shortening, or angulation.
The absence of bulky muscle tissues in the hand prevents the principles of fracture bracing from being literally applied; the finger flexors and dorsal hood mechanism supply stabilizing forces for selected hand fractures.
Fracture bracing is intended to allow anatomic motion and to prevent the introduction of undue external torque forces.
* The author appreciates the thoughtful review of and revision suggestions for this chapter by Brian Laney, OT, CHT; Stacy Huizenga, OTR, CHT; and Alison Thompson, OT.Fracture bracing of the lower extremity, which has been used successfully since the 1970s, has taught clinicians that protected early motion and weight bearing stimulate strong bone formation. August Sarmiento, the primary proponent of fracture bracing, first developed successful strategies for fracture bracing of the lower extremity and later developed applications for the upper extremity. The advantages of early motion in preventing disability and stimulating bone healing demonstrated a decreased need for long periods of fracture immobilization. Simultaneously, developments in hand surgery and hand therapy led to shorter periods of immobilization, which supported the use of fracture bracing in selected stable upper extremity fractures.
Fracture bracing stabilizes long bone fractures of the humerus and forearm by compressing surrounding muscle and soft tissue. The cylinder-shaped brace provides a stabilizing force equal in all directions, which limits motion at the fracture site. Fracture healing in the presence of limited motion is also applied to selected stable fractures of the metacarpals and phalanges. In hand fractures, compression of soft tissue other than muscle provides the needed stabilizing support during active motion.
Many terms have been used to describe the fitting of an external device to stabilize a fracture; the term fracture bracing is used throughout this chapter. Initially, plaster casts with connecting hinges applied to femoral fractures were called cast braces. The use of plastic materials for these cast braces led to the term fracture brace. Sarmiento prefers the term functional fracture bracing because it more accurately reflects the primary advantage of this technique: maintenance of joint motion and muscle function while reducing costs, rehabilitation time, and surgical complications.
For many years, the teachings of Hippocrates encouraged physicians to immobilize the joints above and below a fracture, believing this was required for fracture healing. In 1767, Gooch described tibial and femoral functional fracture braces, but the concept remained obscure for the next two centuries, until in the 1970s Sarmiento left the ankle free in a tibial cast and created the first modern functional brace. He demonstrated the advantages of early functional motion and led a renaissance of treatment techniques based on a new idea: early motion facilitates bone healing. The availability of thermoplastic orthoses and a new generation of casting materials has greatly advanced the popularity of this technique.
Any technique that lessens the period of disability and reduces complications must be considered the treatment of choice. Colton has succinctly described the advantages of functional fracture bracing: “The widespread use of functional bracing has liberated countless patients from prolonged hospitalization and permitted early return to function and to gainful employment.”
Principles of Fracture Bracing
The observation that the clavicle and the ribs heal without complication in the presence of motion provides the evidence that fractures do not need to be immobilized to heal. This knowledge has caused us to examine more closely the two ways in which bone heals. Primary healing occurs in rigidly immobilized fractures; secondary healing occurs when there is motion at the fracture site.
In primary healing, accurately approximated bone ends encourage the formation of medullary callus. Because the diameter of this callus is small, the callus is mechanically inferior to the callus of a fracture that is allowed to move during healing. When bone heals secondarily, periosteal callus forms around the fracture site, creating a larger and stronger external callus. In its early stages this callus is pliable, but as it matures it provides increasing stability to the fracture as tissue differentiation occurs. This periosteal callus formation is stimulated by motion at the fracture site, although excessive motion is detrimental to healing. The bone ends moving on one another create a vascular reaction, stimulating capillary invasion from the soft tissue to the fracture site, which in turn causes profuse osteogenesis and more rapid union. The rapid healing of fractures with exuberant callus formation in patients with involuntary motion caused by cerebral irritation is partially attributed to frequent motion occurring at the fracture site.
Periosteal callus is stronger not only because it is larger in diameter but also because the stress of motion is directed to the periphery of the callus. Thus bone forms in the periphery of the callus before it forms in the center, accounting for the early strength of secondary fracture healing. Rigid immobilization inhibits production of external callus. The purpose of a functional fracture brace is to provide fracture alignment stability but not rigid immobilization of the bone ends. Because bone deprived of stress undergoes atrophy, proponents of fracture bracing believe that prolonged rest and immobilization of joints above and below a fracture are actually detrimental to fracture healing. Although the trabeculae of the bone return to normal anatomy more quickly in rigidly immobilized fractures, functional motion supported by the bone occurs much more quickly when external callus forms. It is the “controlled” motion within the fracture brace that is the desirable stimulus to healing.
Design Principles of Fracture Braces
Functional fracture bracing is accomplished by applying an external cylinder around a fractured long bone. This cylinder restrains soft tissue expansion, directing force equally in all directions internally during muscle contraction ( Fig. 127-1 ). As muscles contract within the rigid cylinder, their attempted increase in size is translated into compressive forces within the cylinder. Sarmiento describes this as a pseudohydraulic environment. This internal force mechanically stabilizes the fracture. The concept of soft tissue containment does not depend on the strength of the cylinder material, but rather on the inherent size and shape of the cylinder. The cylinder allows consistent pressure to be exerted on the fracture during active muscle contraction.
The ability of soft tissues to provide stability was shown dramatically by Zagorski and colleagues when they wrapped a piece of meat around a metal hinge and provided external compression by wrapping it with a piece of brown paper. Circumferential brown paper increased the rigidity of the hinge nearly 100 times. Using Orthoplast orthotic material further increased the rigidity only two times over the brown paper, proving that the cylinder shape and not the material rigidity provides fracture stability. Latta and coworkers demonstrated in lower-leg fractures that more than 80% of the load placed on the limb is borne by the soft tissues. They stated, “The brace is not the major load bearing structure.”
Because functional fracture bracing stabilizes but does not immobilize fractures, it is most effective in the treatment of fractures in which initial shortening is within acceptable limits. Most commonly these are closed, low-energy fractures that require little or no reduction. The cylinder shape of the fracture brace is more effective in controlling angulation than rotation or length at the fracture site. The external brace limits but does not totally prevent motion at the fracture site. When the muscles are at rest the brace creates equal compression of the soft tissues. This compression encourages the bone to return to its initial position, preventing progression of deformity.
Although many authors have written about early motion in metacarpal and phalangeal fractures, the absence of bulky muscle tissues in the hand prevents the principles of fracture bracing from being literally applied. The principle of soft tissue support does apply, although it is the finger flexors and dorsal hood mechanism that supply stabilizing forces for selected fractures of these bones. This principle is discussed in greater detail later in this chapter.
Contraindications for Functional Bracing
Fractures that are accompanied by major soft tissue injury or bone loss clearly do not have the necessary soft tissue support, so other means of stabilization are required for these types of fractures. Uncooperative and unreliable patients are thought to be poor candidates for fracture bracing, perhaps because of the attention needed for skin care and hygiene. As previously stated, only fractures with minimal displacement, shortening, or angulation can be adequately treated by this technique.
The humerus, being a single long bone in the upper arm, is an ideal candidate for functional fracture bracing. The brace effectively compresses the bulky biceps and triceps muscles, allowing early shoulder, elbow, wrist, and hand motion (see Fig. 127-1 ). Clinical experience has shown that humeral shaft fractures have a high rate of healing with excellent return of function, except those fractures complicated by radial nerve palsy. There is also some evidence that fractures in the distal third of the humerus have a lower healing rate than more proximal fractures of the humerus. Unlike the smaller bones of the forearm and hand, less than full anatomic reduction of the humerus can accompany a full functional result.
In addition to humeral shaft fractures, distal humeral fractures also may be managed by fracture bracing. A hinge is sometimes used at the elbow to allow elbow flexion and extension but prevent varus–valgus and translational forces ( Fig. 127-2 ). Good results have also been reported without use of the hinge. Proximal humeral fractures also can be treated effectively with the circumferential brace, even though it does not encompass the fracture. The compression of the soft tissue provides enough stabilizing force to stimulate healing. Thus the use of a fracture brace is effective regardless of the level of the humeral fracture.
Some authors advocate immediate fitting of the plastic brace over cast padding. Patients generally are treated with a plaster coaptation orthosis (anterior and posterior plaster slabs held in place with an elastic wrap) until the swelling and pain have subsided. The humeral fracture brace is then fitted 7 to 10 days after injury, when edema and pain are diminished.
Long periods of immobilization of the injured upper extremity are fraught with complications caused by stiffness. These complications often necessitate extended periods of rehabilitation. Fracture bracing of the humerus provides stabilization of the fracture while shoulder and distal joint motion is maintained. All of the muscles crossing the humerus (biceps, triceps, and brachialis) run parallel to the long axis of the humerus. Active contraction of these muscles reestablishes accurate alignment and rotation; this explains why functional deformities are rare in the presence of active motion. Sarmiento and colleagues describe spontaneous correction of angulatory deformities after shoulder pendulum motion and elbow motion in their review of 51 humeral fractures.
Initially, for comfort and support, an arm sling is applied in addition to the fracture brace. The sling is removed frequently for exercises, and as callus formation provides increasing stability the sling is discontinued. The increasing comfortable range of motion (ROM) allows use of the injured arm for assistance with self-care and activities of daily living. The plastic fracture brace must be removed daily for skin hygiene, application of a clean stockinette liner, and optional application of cornstarch or baby powder to retard perspiration. Stockinette under the brace acts as an efficient liner to reduce skin friction and to absorb perspiration.
Patients are often apprehensive about removal of the brace at home. They should be instructed to sit in an armless chair, supporting the injured arm in the lap with the elbow flexed. The patient then leans the trunk toward the injured side, thus allowing the arm to hang freely. This creates room between the body and the arm to allow an assistant to comfortably remove the brace. Patients experience no pain during removal of the brace if the muscles in the injured arm remain fully relaxed and gravity maintains longitudinal alignment. However, active abduction of the humerus results in painful motion at the fracture site.
Most authors agree that certain exercises should be started immediately after the application of the cast, and some also advocate immediate passive exercise. I prefer an early focus on active pendulum exercises together with active flexion and extension of the elbow, as well as active resistive finger flexion. External rotation of the shoulder or active or passive abduction of the shoulder encourages external rotation or angulation of the distal fracture fragment, so these positions must be avoided. The patient should be instructed to keep the hand near the midline of the body when the elbow is flexed or at the side of the body when the elbow is extended (except during pendulum exercises). The arm should not be abducted away from the body, nor the elbow propped on a surface, nor a pillow or other object placed between the arm and the body.
Initially, the frequency of exercises is limited by the patient’s pain and apprehension. Within 1 week of fracture brace application, the patient should be able to comfortably exercise two to four times daily. Sarmiento suggests avoidance of early active shoulder flexion and abduction exercises until fracture stability has developed because he believes that these exercises contribute to angulation. He states that pendulum and circumduction are the only exercises necessary during the first few weeks. Surgeons experienced with the use of functional bracing for humeral shaft fractures agree that hand therapy usually is needed only in the first few weeks after fracture, unless there are other concomitant injuries or complications.
Construction and Application
Humeral Shaft Fracture Brace
The design of the humeral fracture brace must allow full shoulder and elbow ROM, and therefore designs with shoulder caps should be avoided ( Fig. 127-3 , online). A one-piece circumferential design with an overlapping long edge made of a thin thermoplastic orthotic material ( -inch thickness) is ideal to provide tissue compression. This material is flexible enough to allow easy application and removal of the brace and also to accommodate the decreased circumference as edema subsides ( Fig. 127-4 , online). Radiographic examination of the fracture is facilitated by the radiotranslucent plastic materials used to construct the brace.
The cylinder is closed with a circumferential hook-and loop-strap with a D -ring component. This strapping configuration allows the patient to securely close the cylinder and easily adjust the tension with one hand ( Fig. 127-5 ).
Circumferential braces made of thicker and more rigid materials allow more unwanted angulation. To avoid this problem, some advocate a brace with anterior and posterior components. Only if the material itself is rigid is this two-part design necessary to provide adequate soft tissue compression. Applying a two-part brace so the two pieces sit opposite over the apex of the angulation minimizes the final angulation. Sarmiento and colleagues have demonstrated a progression from a relatively rigid one-piece polypropylene brace to a more compliant polyethylene brace. The soft tissue must be entirely encircled by the flexible brace to respect the basic principle of soft tissue encasement and to provide adequate stability and compression.
Both custom and prefabricated braces have proven effective in stabilizing the humeral shaft, although care must be taken to ensure accurate fit and compression with prefabricated braces (see Figs. 127-3, online, and 127-6 ). Some authors complain of the time-consuming, expensive fitting of the brace when fabricated by an orthotist. The high-temperature permanent materials used by orthotists are unnecessary in the uncomplicated humeral fracture because the fracture brace is worn for a relatively short time. Therapists who frequently construct orthoses can, in one office visit, easily construct and fit a cost-effective humeral fracture brace from a low-temperature thermoplastic material as well as instruct patients in early motion exercises. Additionally, if early problems arise with edema or orthosis fit, the therapist is the referral of choice for solving such problems. The application of a circumferential hook-and-loop strap with D -ring closure allows the patient to adjust the brace consistently for steady pressure and to decrease the size of the brace as edema subsides. Initially patients are prone to tighten the brace excessively in an attempt to prevent the sensation of movement of the bone fragments. It is helpful to explain to the patient that this sensation is normal and not detrimental, since excessive tightening of the brace results in increased distal edema. The brace must be fitted with the patient’s arm completely relaxed, allowing gravity to assist in alignment of the fragments. Patients usually react by contracting their muscles to hold the arm still. With a fractured humerus, this muscle contraction causes the deltoid to pull on the proximal fragment, increasing angulation and causing pain. Asking the patient to lean the torso laterally (toward the involved side) approximately 30 degrees from vertical allows the arm to hang vertically while providing room for the therapist to work between the arm and body ( Fig. 127-7 , online). The patient holds the hand of the injured arm in his or her lap with the uninjured hand, allowing the elbow to rest at a 90-degree angle.