AAOS Bulletin - December, 2005

Complications from casting

Pitfalls & Pearls

By John H. Harp, MD

The cast is one of the most recognized emblems of orthopaedic treatment. Yet even casting can result in an increased risk of liability if: (1) the patient is dissatisfied with the outcome; (2) the patient’s level of disability is high at the conclusion of treatment (regardless of the cause); or, (3) there is a catastrophe of some sort. Here are some basic pitfalls to be aware of and some pearls of advice to help you avoid problems.

Sources of patient dissatisfaction

Patients may be dissatisfied with the outcome of their treatment for several reasons. The most common problems are skin ulceration/breakdown, neurologic injury, thermal injury, abrasions and pain.

To avoid problems with skin ulceration or breakdown when using casts, remember that patient selection is important. Patients with impaired sensation due to neuropathy or neurologic injury are at higher risk for skin breakdown because they can’t feel burning or pain under a cast. In these situations, modify the cast technique (such as using total contact casting for diabetic foot ulcers) or avoid casting altogether and use a removable brace that will allow frequent periodic skin checks.

Neurologic injury can be avoided with careful padding. Never apply cotton padding to the elbow except when it is in the final flexed position for casting or splinting. Anterior interosseous nerve palsies can result if padding is placed around the elbow before the joint is moved to a final flexed position. The padding can form a wedge and compress the antecubital fossa. Additional compression can occur when blood-soaked cotton padding dries and turns into a constrictive dressing.

The common technique of wedging for improving alignment without recasting femur fractures in hip spica casts can lead to transient peroneal nerve palsies. Careful neurologic exam after wedging is recommended.

Thermal injury and abrasions may result from the use of cast saws and inadequate padding, operator inexperience, or dull blades. A flexible metal strip placed between the padding and skin will provide some protection. Although these injuries are usually minor, they can be a source of patient dissatisfaction and lead to a compensation claim.

The exothermic heat released during application of a plaster brace or cast also can result in skin burns. Contributing factors may be technical (thickness of plaster, dipping water temperature, tourniquet use, insulators such as pillows) and patient-related (vascular disease, edema, local anesthetic use, cardiac and renal failure). If accelerants leach out from the plaster into the dipping water, the cumulative effect may result in increasing exothermic heat.

Pain may result when fiberglass or plaster cast materials are applied with a constant tension on the roll. Keeping the roll in contact with the cast can increase pressure on the skin. This pressure is not relieved until the cast is cut and spread. Applying a fiberglass cast with the “stretch-relax” technique minimizes this increased pressure. The roll is pulled away from the cast to unwind the material, and then the material is laid without tension onto the cast.

Bivalving a cast relieves pressure applied from the casting material. A dorsal split in upper extremity casts gives maximum rigidity. Applying an elastic roll bandage over the bivalved cast lets a patient readjust the cast tightness and is very useful in pediatric upper extremity fractures.

Sources of high patient disability

If casting leads to the development of compartment syndrome, deep venous thrombosis (DVT) or pulmonary embolism, the patient will have a higher level of disability and may file a medical liability lawsuit.

Using a hip spica cast to treat a pediatric femur fracture may result in compartment syndrome, due to the cast building sequence of body-leg-femur. There is a tendency to apply traction to the femur via the leg cast, and then to fix it in this position when applying the femur portion of the cast. This may result in unacceptable compression of the popliteal fossa and dorsum of the foot as the tension in the thigh pulls the leg into an extended position inside the cast.

Compartment syndrome can occur even in the absence of excessive traction, possibly due to the calf compression of the affected leg. The safer sequence for applying the cast is to do the above-the-knee portion first, using heel support instead of calf support. Then build the rest of the cast, excluding the foot. Carefully pad the groin to avoid compression. Leave the foot out of the cast to enable neurological examination. Do not hesitate to remove the cast and measure compartment pressures.

Outpatient care of fractures with casts increases the risk of delayed diagnosis and treatment of compartment syndrome. Children carry a higher liability risk for several reasons, including the high frequency of closed treatment of pediatric fractures, the frequent “atypical” appearance of compartment syndrome, the life-long high level of disability and the fact that a crippled child is a very powerful courtroom plaintiff.

Strategies to minimize the risk of liability include a redundant system for patients or families to report increasing pain and/or to return for evaluation. This system should include:

• Patient and family education about compartment syndrome in the post-operative discussion—Patients and caregivers should be encouraged to call or return to the physician’s office, hospital or emergency room if they have any concerns about increasing pain.

• A “Black Box” warning in discharge instruction to reinforce and document the post-operative discussion (Fig. 1)

• A triage system for calls about cast pain by a physician, nurse or physician assistant

• A reliable system for answering and documenting after-hours or weekend patient calls

• A back-up plan for evaluation by an emergency room doctor or partner if the on-call surgeon is in the operating room

• A strong doctor-patient relationship

Again, the surgeon should have a low threshold for removing the cast and measuring the compartment pressures directly. Loss of reduction and recasting carries minimal liability risk, but a missed compartment syndrome can result in a settlement that exceeds the surgeon’s limits of liability.

Multiple studies have reported an association between DVT and lower extremity cast immobilization, with an approximate 20 percent incidence. There is no consensus on whether prophylactic anticoagulation is indicated. Vigilance and close follow-up are recommended.

Catastrophic outcomes

Occasionally, catastrophic outcomes have resulted from cast application. A 1993 report identified a patient death from systemic complications after compartment syndrome related to cast application for an ankle fracture. A death shortly after cast removal in an 18-month-old boy with cardiomyopathy, likely due to an arrhythmia induced from the anxiety, was reported in 2001.

Even the most mundane procedure such as closed treatment of a fracture can carry a significant liability risk. Good risk management also results in superior patient care.

John H. Harp, MD, is a member of the Professional Liability Committee. Literature references for this article are available from Dr. Harp at harpjh@tetonortho.com

    Casts and post-operative plaster splints are useful devices to immobilize an extremity after surgery.



    Fig. 1 - “Black Box” warning on discharge instructions for all casts.

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