INTRODUCTION — Immobilization provides the basis for fracture healing. For many complex and unstable fractures, immobilization is achieved by means of internal fixation. However, many stable fractures at low risk of displacement can be immobilized effectively with casting, which can be performed by orthopedists or knowledgeable primary care clinicians.
The basic principles and techniques of casting and the follow-up care needed for patients treated in this manner are reviewed here. The assessment and initial management of acute fractures is discussed separately. (See "General principles of fracture management: Bone healing and fracture description" and "General principles of acute fracture management".)
Overview — Casting is standard treatment for many closed, nondisplaced, or reduced fractures . Casts provide a stable, protected environment in which the external, periosteal callus can form and normal bone healing can proceed .
The optimal time to place a cast is after post-traumatic swelling has resolved. This usually takes five to seven days following an injury but varies depending upon the location and type of fracture. Most often a splint is used in the interim. Nevertheless, several fracture types are best managed with acute casting. In such cases, the casts are either maintained in a single piece or converted into functional splints by creating "valves" in the cast (ie, two incisions along the entire length, thereby dividing the cast into two pieces) that can accommodate some soft tissue swelling.
Fractures likely to require casting acutely include those with the following characteristics :
●Reduction was required
●Two adjacent bone are involved (eg, fracture of radius and ulna)
●Fractures where muscles exert strong forces that may cause displacement
Some fractures, such as those of the proximal humerus, are not amenable to casting, while others that should be casted, such as certain ankle fractures in children, are often not . Nevertheless, casting remains the treatment of choice for most nonoperative fractures. Successful casting requires three things: proper materials, proper positioning, and selection and application of the appropriate type of cast. These are discussed below.
Materials — Myriad materials are available for casting, but, fiberglass and plaster of Paris are the most widely used and least expensive. Fiberglass is lighter, stronger, more breathable, and sets more quickly than plaster (picture 1) . According to a laboratory study using a prosthesis model of limb swelling, fiberglass applied with a stretch-relax technique accommodates swelling better and causes less skin surface pressure than plaster . However, fiberglass is a skin irritant, and clinicians should wear gloves when applying a fiberglass cast. (See 'Application of cast' below.)
Fiberglass and related synthetics are "waterproof" and, when combined with an appropriate padding material, can be used to make a cast that can be used in the water without significant breakdown. (See 'Keeping casts dry' below.)
Plaster molds more uniformly than fiberglass, which is an advantage in maintaining fracture reduction. Plaster also sets more slowly, making it easier for less experienced clinicians to apply it correctly. However, plaster tape is messier, heavier, and breaks down more easily than fiberglass tape, and it can produce a significant exothermic reaction while it sets. For these reasons, many clinicians prefer fiberglass for most casting applications.
Protection of the skin from the overlying fiberglass or plaster is essential to prevent breakdown and related complications. Skin protection begins with the application of a stockinette, the first layer of any cast, followed by adequate but not excessive amounts of padding (picture 2 and picture 3). Both stockinette and cast padding have traditionally been made of cotton, but synthetic materials are becoming available. Several forms of synthetic stockinette and padding materials are designed to allow for the cast to become wet.
It is important to use the appropriate amount of padding, especially over bony prominences, which are susceptible to pressure and skin breakdown from the cast. Extra padding is often needed in such areas (eg, lateral epicondyle, ulnar styloid, medial and lateral malleoli). However, care must be taken to avoid excess padding, especially around the fracture site, as this can lead to a loose cast that provides inadequate immobilization .
Type of cast — When selecting the appropriate cast, the clinician must determine which joints to include and how far the cast should extend. Maximal immobilization is achieved with casts that include the joints proximal and distal to the fracture site. This is important in treating any unstable fracture, such as a reduced distal radius fracture. Whenever possible, the entire length of the fractured bone should be included in the cast . The accompanying table describes several common casts and the fractures for which they are best suited (table 1).
Application of cast — The key steps in the application of a fiberglass cast are outlined below. For illustrative purposes, a short arm cast with a thumb spica is described, but the basic steps apply to all fiberglass casts. Cast selection for specific injuries are found in the UpToDate topics devoted to that injury. Descriptions of how some other types of casts are applied are found separately: Long leg cast: (See "Tibial shaft fractures in adults", section on 'Long leg casting'.) Standard short arm cast: (picture 4)
●Select the appropriate padding and width for casting (fiberglass or plaster) tape. Two-inch (5 cm) tape is generally good for the hand, 3 inch (7.5 cm) for the forearm, and 4 inch (10 cm) for the lower extremity and upper arm (picture 3). The stockinette width is also based on the size of the limb being casted (picture 2). Cutting the stockinette slightly longer than the cast allows for the edges to be rolled back prior to the application of the final layer of casting material, providing a smooth edge to the cast.
●First apply the stockinette (picture 5). Next, apply the padding (eg, Webril) by rolling it onto the extremity in a distal to proximal direction; each layer should overlap the preceding layer by approximately 50 percent (picture 6). Additional Webril or padding should be placed over bony prominences. In general, about two layers of padding are adequate for the upper extremity; three to four layers are used for the lower extremity.
●Once the padding is in place and the limb properly positioned, moisten the casting tape (picture 1). Cool water should be used for fiberglass tape. "Tepid" or room temperature water works well for plaster. Warmer water will shorten the set time, but may cause skin burns.
●Roll the casting tape over the extremity moving distal to proximal (picture 7). When applying fiberglass tape, stretch and then relax the tape during application to reduce the skin surface pressure .
●Special cuts can be used to help navigate smaller areas, such as around the thumb. This helps to prevent bulking of the cast and can improve comfort.
●After the first few layers of casting tape are applied, the cast should be molded if necessary (picture 8). The goal of molding is to maintain alignment of an unstable fracture. An oval or elliptical shaped cast is better suited for maintaining fracture alignment than a perfectly cylindrical cast .
Improper molding or any sharp indentations in the cast can cause severe complications, such as pressure sores and skin ulcers. Clinicians with little experience casting should limit molding to gently compressing the cast into an elliptical shape at the area of the fracture. The palms and heels of the hands should be used; avoid using fingers . This approach provides adequate molding while decreasing the risk for skin breakdown.
Practitioners with experience casting may use a three-point molding technique. The first point of compression is directly over the apex of the fracture with the force directed opposite the direction in which the fracture is most likely to displace. The two remaining pressure points lie on the opposite side of the bone at either side of the apex. Force is maintained at these three sites until the cast has set. As described above, the palms and heels of the hand should be used to apply pressure and use of the fingers avoided.
●Fold the ends of the stockinette over the set casting tape and apply the final layer of tape (picture 9). In all, two layers of fiberglass tape are usually sufficient for short arm casts, three layers for long arm casts and non-weightbearing short leg casts, and four layers for weightbearing short leg casts (picture 10).
●Inspect the cast to ensure that there are no rough or sharp edges protruding and that sensation and blood flow distal to the cast end are intact. Written instructions explaining proper cast care should be provided to the patient. (See 'Information for patients' below.)
An alternative technique for applying a fiberglass cast may be useful for less experienced clinicians . This approach differs in that the casting tape is not moistened before it is applied. Rather, the fiberglass tape is applied directly out of its packaging and a water based gel, such as KY Jelly, is spread evenly over each roll after it is applied. This technique allows for a longer set time and permits adjustments to be made to casting position after each roll is placed.
The same steps described above are used when applying a short leg cast. A few special considerations for the short leg cast include:
●Cut the stockinette on the dorsal side just over and parallel to the ankle (ie, tibiotalar) joint to prevent wrinkling, which can lead to skin irritation.
●Four-inch padding is needed for lower extremity casts; apply extra padding over bony prominences (eg, malleoli, fibular head).
●Maintain the ankle in 90 degrees of dorsiflexion (ie, neutral position) to create a position of function (especially for weightbearing casts) and to prevent flexion contractures.
●Leave all five toes visible to allow for neurovascular assessment.
Positioning — Casts should place the affected joints in their position of function whenever possible (table 1). The wrist and hand are usually placed in a grasping position. The ankle and elbow are usually casted at 90 degrees. Sometimes these general rules are adjusted to obtain a better outcome. As an example, the wrist may be placed in a more neutral to slightly flexed position to help maintain reduction when treating a distal radius fracture.
Changes in fracture position can occur during cast application despite an optimal reduction and excellent casting technique with proper molding. Therefore, we suggest obtaining radiographs immediately following cast application for any unstable fracture or any fracture that required reduction prior to casting.
Complications — Potential complications associated with fractures are reviewed separately. Complications associated with casting are discussed below. (See "General principles of fracture management: Early and late complications".)
While immobilization in a cast is important for maintaining reductions and provides the basis for fracture healing, it can lead to joint stiffness, muscle atrophy, and disuse syndromes, and increases the risk for thrombosis. Casts that are applied too tightly or that become too tight due to soft tissue swelling can cause vascular compromise. Skin breakdown, compression neuropathy, and acute compartment syndrome can also occur. Any patient in a cast who complains of pain, burning, tingling, or numbness should be evaluated immediately because of these potentially severe complications. (See "Acute compartment syndrome of the extremities" and "Overview of lower extremity peripheral nerve syndromes" and "Overview of upper extremity peripheral nerve syndromes" and "Clinical features and diagnosis of acute lower extremity ischemia" and "Epidemiology, pathogenesis, and risk assessment of pressure-induced skin and soft tissue injury" and "Clinical presentation and diagnosis of the nonpregnant adult with suspected deep vein thrombosis of the lower extremity".)
Depending upon the age and comorbidities of the patient, even routine casting may result in prolonged losses of motion and muscular strength that require treatment with physical or occupational therapy . Other casting complications include skin burns, which are more likely if plaster is used with hot water .
Cast removal — Any clinician who places casts must ensure that the patient has continuous access to cast removal by qualified personnel. Cast removal is not without risk. Cast saw injuries, most often thermal or abrasive, occur in nearly one percent of removals. To reduce the risk of injury during removal, we suggest using an “up-and-down” cutting technique, in which the saw makes a series of cast “punctures” perpendicular to the skin, rather than pulling the blade across the cast (and potentially the skin), along with ensuring that blades are sharp. The following video clip demonstrates this technique and the other major steps in cast removal (movie 1).
The risk of thermal injury may be reduced by using cooling techniques for saw blades that are hot from prior use. According to a laboratory study of six techniques for reducing saw blade temperature, cooling was most rapid with the following techniques: oscillating the blade while using the vacuum; applying 70 percent isopropyl alcohol to the blade with gauze or cast padding; or applying cool water to the blade .
Keeping casts dry — Particularly with children who must wear a cast during warm weather, keeping a cast dry can be a challenge. According to an observational laboratory study comparing six approaches, one effective and inexpensive method for maintaining a dry cast is to enclose the cast in two plastic bags, one over the other, and then seal the bags using duct tape . Two strips of tape are applied circumferentially, one to each bag, with half the tape overlapping the end of the bag and the other half on the skin, as shown in the following photograph (picture 11). This approach was substantially more effective than using a single plastic bag sealed with either a rubber band or duct tape, and equally effective as commercial products. In some cases, commercial products may be more convenient as they can be applied and removed quickly and are reusable.
Synthetic "waterproof" cast padding materials are widely available and increasingly inexpensive. One effect of the coronavirus disease 2019 (COVID-19) pandemic, when it was unacceptable to wear a cast that interfered with handwashing and bathing, has been a widespread shift to waterproof cast liners for routine, nonoperative fractures.
Overview — After the initial cast is applied and fracture alignment is confirmed, the next essential step is to ensure adequate and timely follow up. The interval between visits depends on the nature of the fracture, the type of cast, and any concerns there may be about patient compliance.
Even in the rare instance where no follow up is required (eg, healthy adult with a minor fibular avulsion fracture treated in a pneumatic splint), the clinician should provide clear instructions about whom to call for signs of skin breakdown, infection, neurovascular compromise, or for worsening or persistent pain. Unstable fractures or post-reduction fractures require more frequent reassessment, sometimes as often as twice a week initially to ensure that correct fracture alignment is maintained .
As a general rule, lower extremity casting involves longer immobilization times to maximize stability and strength. Upper extremity casting generally involves shorter periods of immobilization in order to retain range of motion (ROM) .
Follow-up visits for stable fractures — Initial follow up after casting of a stable fracture is usually scheduled three to seven days later, with instructions to call or return earlier for pain, swelling, or other acute symptoms. Subsequent follow-up visits vary according to the patient and cast but are usually scheduled about every two to three weeks.
At each follow-up visit, the cast should be carefully checked for signs of wear and proper fit. The cast should be replaced if it is too loose, too tight, or excessively worn. Most weightbearing plaster casts maintain their integrity for two to three weeks, while non-weightbearing plaster casts last about four weeks. Fiberglass casts typically remain intact for two weeks longer than their plaster counterparts. These time frames are approximations and depend on patient activity, weight, and age. The casts of children and active adults should be checked more frequently to ensure proper immobilization .
Follow-up visits are ideal venues for teaching appropriate rehabilitative exercises and ensuring compliance with activity restrictions.
Follow-up visits for unstable fractures — Unstable fractures are prone to loss of reduction or malalignment while being treated in a cast. The proper times to recheck alignment depend on the fracture type and the age of the patient.
As an example, pediatric both-bone forearm fractures are among the most unstable fractures. Since children heal at a relatively rapid rate and only limited degrees of angulation are acceptable in the forearm, midshaft fractures of both the radius and ulna require radiographic follow-up two times per week for the first two to three weeks after injury.
Conversely, angulated distal radius fractures in adults need only be reassessed once every 7 to 10 days post-injury. If excessive angulation is noted at that time, the bone can be re-manipulated because fracture fragments remain relatively mobile in adults.
Radiographs to reassess fracture alignment in unstable fractures while they are healing should be obtained in the cast. Radiographs taken in traditional plaster or fiberglass generally provide sufficient clarity to judge the alignment of long bone fractures, although evidence of healing may be obscured. Several types of casting tape offer superior radiolucency (eg, 3M Scotchcast, M-PACT OCL Polylite), which may be helpful when evaluating unstable fractures .
Orthopedic referral — Between visits, patients can develop complications that warrant orthopedic evaluation. As an example, unacceptable changes in fracture angulation may appear on follow-up radiographs and orthopedic consultation should be obtained in such cases to determine the best treatment. Any new deficit in neurovascular function requires immediate evaluation by an orthopedic surgeon.
FRACTURE HEALING — The goal of casting is to provide a sufficient period of immobilization such that the fracture heals properly. However, prolonged immobilization increases the risk of complications. An accurate assessment of fracture healing is essential to striking a balance between these twin considerations. Unfortunately, determining when clinical union has occurred can be problematic. Understanding the basic biology of bone healing and then relying on a combination of clinical and radiographic factors offers the best estimation of when a fracture is adequately healed . (See 'Complications' above.)
Biology of fracture healing — The biology of bone healing is discussed separately. (See "General principles of fracture management: Bone healing and fracture description", section on 'Biology of bone healing'.)
Clinical assessment of fracture healing — Proper assessment of clinical union is essential to optimize fracture healing and to prevent complications from excessive immobilization. Biomechanical studies of fracture stiffness show that clinical union typically occurs one to two weeks before evidence of radiographic union [11,12]. Additionally, radiologic parameters of fracture healing have poor interobserver correlation , and tend to underestimate healing progress when compared with clinical , biomechanical [11-13], and histologic  measures.
Given the limitations of radiographic parameters, typical clinical practice is to schedule a follow-up visit around the time of expected healing, usually around four to six weeks post-injury. The cast is removed and clinical features of healing are assessed. These can include the ability to bear weight , no tenderness to palpation at the fracture site , and stability and absence of pain with manual stress testing . If the fracture demonstrates clinical healing and appropriate signs of healing are seen on radiographs, then the fracture is deemed healed and the patient begins rehabilitation. If the fracture does not demonstrate signs of clinical healing or appropriate healing is not seen on radiographs, a cast is reapplied. Alternatively, a functional splint or brace, which allows for some gentle range of motion (ROM) exercises to be done out of the device, can be used. The fracture is then reassessed in two weeks.
Fracture healing depends on multiple biologic and biomechanical factors and some patients may need to be recasted several times. If a fracture is not clinically healed four weeks after the expected time of healing, additional confirmation of bony healing should be sought through advanced imaging (magnetic resonance imaging [MRI] or computed tomography [CT] scanning) and consultation with an orthopedic surgeon.
As a general rule, lower extremity casting involves longer immobilization times to maximize stability and strength. Upper extremity casting generally involves shorter periods of immobilization in order to retain ROM .
ADJUNCTIVE THERAPY FOR FRACTURE HEALING
Overview and basic measures including nutrition — A number of adjunctive therapies are used to aid fracture healing. While a detailed discussion is beyond the scope of this review, a brief description of some of the more commonly mentioned therapies is included here. Pain management for patients with fractures and the effects of specific drugs on fracture healing are discussed separately. (See "General principles of acute fracture management", section on 'Pain management' and "General principles of fracture management: Early and late complications", section on 'Nonunion and malunion'.)
For all patients with fractures, regardless of the site, it is important to ensure good nutrition, including adequate intake of vitamin D, calcium, and protein, to maximize fracture healing. Although evidence exists to support the role of vitamin D in fracture prevention, no direct evidence supports the use of supplemental vitamin D for the treatment of acute fractures. However, an observational study of 73 patients with tibia and femur fractures noted that serum vitamin D concentrations drop during the early stages of fracture healing, suggesting an increased need . In addition, vitamin D increases intestinal calcium absorption and cell proliferation and differentiation, changes that promote fracture healing . Encouraging increased exposure to natural sources of vitamin D or prescribing supplemental vitamin D during the period of active fracture healing seems a reasonable practice given the prevalence of vitamin D deficiency in the general population and the low potential for toxicity. If supplemental vitamin D is prescribed, a daily dose of 1000 international units during fracture healing seems reasonable. (See "Vitamin intake and disease prevention", section on 'Vitamin D' and "Overview of vitamin D".)
While evidence is limited, the results of a small number of controlled studies and multiple animal studies suggest that ensuring adequate daily protein intake aids bone healing, helps to maintain lean muscle mass, and may reduce complications among patients recovering from a fracture [17-19]. Generally, this can be accomplished by eating protein-rich foods. Assuming normal kidney function, daily protein intake of about 2 grams per kg of bodyweight is a reasonable approach.
Cigarette smoking and excessive alcohol consumption impairs fracture healing. Patients should be encouraged to stop smoking and limit alcohol consumption. (See "General principles of fracture management: Early and late complications", section on 'Nonunion and malunion' and "Overview of smoking cessation management in adults" and "Overview of the risks and benefits of alcohol consumption" and "Approach to treating alcohol use disorder".)
Systemic therapies — A wide range of pharmacologic treatments to accelerate fracture healing are being studied. Such treatments include growth hormone (GH), bone morphogenetic proteins (BMP), parathyroid hormone (PTH), platelet-derived growth factor, and bisphosphonates. Most studies are preliminary and the appropriate role for these therapies in the treatment of acute fractures remains speculative [20-23]. The use of teriparatide for fracture healing (and other indications) is reviewed separately. (See "Parathyroid hormone/parathyroid hormone-related protein analog therapy for osteoporosis", section on 'Fracture healing'.)
Local therapies — Locally injected or applied treatments to improve fracture healing, such as platelet-rich therapies, are under investigation. However, studies are preliminary and the appropriate role for such therapies in the treatment of acute fractures remains speculative .
Prevention of complex regional pain syndrome — Complex regional pain syndrome (CRPS), also known as reflex sympathetic dystrophy, is a complex disorder of the extremities characterized by localized pain, swelling, limited range of motion (ROM), vasomotor instability, skin changes, and bone demineralization. Fractures, with or without a nerve injury, are a common inciting event. Measures to prevent this debilitating syndrome, including supplemental vitamin C, are discussed separately. (See "Complex regional pain syndrome in adults: Treatment, prognosis, and prevention" and "Complex regional pain syndrome in adults: Pathogenesis, clinical manifestations, and diagnosis".)
Nonpharmacologic adjuncts — Several nonpharmacologic interventions have been used to aid fracture healing. Among these are electromagnetic stimulation ("bone stimulators") and ultrasound. Electromagnetic stimulation is used most often to hasten healing after internal fixation or bone grafting that has been performed for fractures that failed to heal with standard treatment (ie, nonunions) . Electromagnetic bone stimulation is often used to augment a trial of conservative therapy in atypical or stress fractures that would otherwise require surgery, and limited evidence suggests that these interventions are effective [26-28].
Although the US Food and Drug Administration (FDA) has approved low intensity pulsed ultrasound (LIPUS) for the treatment of acute fractures and nonunions, debate continues about the quality of the evidence supporting this intervention . A systematic review and meta-analysis of 12 studies (including eight randomized placebo-controlled trials) including 648 fractures, found the available studies to be highly heterogeneous and methodologically limited (study methods and the risk of bias were often unclear), and concluded that the evidence does not support routine use of ultrasound for fracture healing . A subsequent randomized trial involving just under 500 patients with tibial shaft fractures reported no difference in radiographic healing or in functional measures between patients treated with LIPUS compared with those treated with a sham device . Another systematic review of 26 randomized controlled trials involving patients with any kind of fracture or osteotomy, concluded that LIPUS does not improve outcomes important to patients (eg, time before return to work, need for subsequent operation) .
ADDITIONAL INFORMATION — Several UpToDate topics provide additional information about fractures, including the physiology of fracture healing, how to describe radiographs of fractures to consultants, acute and definitive fracture care (including how to make a cast), and the complications associated with fractures. These topics can be accessed using the links below:
SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: General fracture and stress fracture management in adults" and "Society guideline links: Acute pain management".)
INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.
Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)
●Beyond the Basics topic (see "Patient education: Cast and splint care (Beyond the Basics)")
SUMMARY AND RECOMMENDATIONS
●Benefits and timing of casting – Casts provide a stable, protected environment in which the external periosteal callus can form and normal bone healing can proceed. The optimal time to place a cast is after post-traumatic swelling has resolved, which usually takes five to seven days. (See 'Overview' above.)
●Cast materials – Fiberglass and plaster of Paris are the two most common types of fracture "tape" used for casting. Fiberglass is lighter, stronger, more breathable, and sets more quickly than plaster. Plaster molds more uniformly and may be easier for less experienced clinicians to use. (See 'Materials' above.)
●Cast application – The steps involved in applying a cast are described in the text; common casts and their application are summarized in the accompanying table (table 1). For proper cast application, it is important that the clinician do the following:
•Protect the skin with a stockinette, the first layer of any cast, and adequate but not excessive amounts of padding.
•Use extra padding over bony prominences.
•Ensure maximal immobilization for unstable fractures by including the joints proximal and distal to the fracture site in the cast.
•Casts should place the affected joints in their position of function (ie, neutral position) whenever possible. (See 'Application of cast' above.)
●Cast complications – Casting has several potential complications, including pressure sores, neurovascular compromise, acute compartment syndrome, and disuse atrophy. Therefore, any patient in a cast who complains of pain, burning, tingling, or numbness should be evaluated immediately. (See 'Complications' above.)
●Follow-up visit scheduling – The intervals between follow-up visits depend on the nature of the fracture, the type of cast, and any concerns there may be about patient compliance. Children with unstable fractures need to be reexamined frequently, in some cases as often as two times each week; responsible adults with stable minor fractures may require only one follow-up visit. (See 'Follow-up visits' above.)
●Clinical assessment of healing – A combination of clinical and radiographic factors offers the best estimation of fracture healing. Assessment of healing is usually performed around the time when union would normally be expected. (See 'Clinical assessment of fracture healing' above.)
●Nutrition and adjunctive therapies – All patients with fractures require good nutrition – including adequate vitamin D, calcium, and protein – to maximize fracture healing. A daily dose of 1000 international units is reasonable if a vitamin D supplement is used. Assuming normal kidney function, daily protein intake of about 2 grams per kg of bodyweight is reasonable.
A number of adjunctive therapies for fracture healing are available, but few rigorous studies have been performed, and the appropriate role of such treatments remains to be determined. (See 'Adjunctive therapy for fracture healing' above.)