Single-Leg Spica Cast Application for Treatment of Pediatric Femoral Fracture

Abstract

Use of a single-leg spica cast for femoral fractures in ambulatory children 1 to 5 years of age facilitates care and mobilization of the patient. It may allow a shorter duration of cast treatment than is possible with a traditional one and one-half-leg spica cast, particularly in patients 1 to 3 years of age. The single-leg spica is indicated for children who are small enough to be lifted safely in the cast and who have an isolated, closed, low-energy femoral shaft fracture. The procedure consists of the following steps:

• Step 1: Obtain adequate sedation. General anesthesia should be used in the operating room, whereas conscious sedation may be used in the emergency or procedure room setting. The location of the procedure should be determined by available resources.

• Step 2: Determine the position of optimal alignment by visual examination of the thigh and leg. If intraoperative imaging is available, assess fracture stability by performing the telescope test described by Thompson et al.¹—i.e., by gently applying axial load to the thigh to assess for shortening under fluoroscopic monitoring. Shortening of >3 cm reflects substantial periosteal stripping and is associated with an increased risk of loss of reduction in the cast. Alternative stabilization techniques should be considered for grossly unstable fractures with a positive telescope test. Use of intramedullary nails, external fixation, or traction with delayed cast application may decrease the risk of excessive shortening or unacceptable angulation of the fracture in the cast.

• Step 3: Apply a stockinette or waterproof pantaloons cast liner to the torso and involved lower extremity.

• Step 4: Position the patient on a spica-cast application table, which provides a support under the thorax and head with a strut that supports the spine and pelvis to the sacrum, allowing application of the cast material to the pelvic area and involved extremity. Position the patient on the table with the involved extremity flexed 30° to 60° at the hip and 30° to 60° at the knee and the contralateral leg supported. Greater flexion makes it easier to fit the child into a car seat or high chair and to carry him/her on the caretaker’s hip, whereas flexing the hip and knee less allows the patient to bear weight more easily. However, Illgen et al.² found knee flexion of <50° to be associated with an increased risk of reduction loss. More proximal fractures are better treated with greater hip flexion because of their tendency to drift into apex anterior angulation.

• Step 5: Overwrap the cast liner from nipple line to ankle with cotton or synthetic undercast padding to prevent pressure sores. Some families prefer waterproof cast padding as it allows the child to be immersed for bathing, but it provides less padding at pressure points and increases the cost of the cast.

• Step 6: Apply fiberglass or plaster cast material starting 1 in (2.5 cm) below the edge of the cast padding and ending 1 in above the malleoli to allow the edges of the cast to be adequately padded when the liner is folded back.

• Step 7: Apply an iliac crest mold to stabilize the hip, and apply an anterior and valgus mold to the involved thigh to recreate the anterior bow and address the tendency of femoral shaft fractures to drift into varus.

• Step 8: Trim and finish the cast. Inspect the groin region for rough edges and trim them as needed using the cast saw or bandage scissors. Cast edges should be “petalled with” (covered with short strips of) moleskin as needed.

• Step 9: After the cast is hard, remove the patient from the spica table and wake him/her up. Place a smaller diaper over the groin inside the cast to prevent cast soiling and a second, larger diaper over the outside of the cast to hold the smaller diaper in place.

Following cast application, distal neurovascular status is assessed. The caretakers are trained in cast care and safe patient transport. The fit of the car seat is checked prior to discharge from the emergency room or hospital. Follow-up radiographs with the patient in the cast should be obtained 10 days after cast application. Angulation of ≤15° and shortening of <2 cm can generally be accepted in patients with a midshaft fracture. Angulation of >15° can often be managed with wedging of the cast in the clinic. Excessive shortening may require reapplication of the cast or a change to another stabilization method. Single-leg spica treatment of femoral fractures in children ≤5 years of age has provided reliable outcomes with few complications. Usually, the cast can be removed 4 to 6 weeks following application.

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