Pediatric Both Bone Forearm Fracture Case File

Pediatric Both Bone Forearm Fracture Case File

Eugene C. Toy, MD, Andrew J. Rosenbaum, MD, Timothy T. Roberts, MD, Joshua S. Dines, MD

CASE 14

An 8-year-old right-hand-dominant girl presents to the emergency department (ED) with severe left forearm pain. Her mother states that the girl had been playing on their trampoline with some friends when she fell, landing on her outstretched left hand 1 hour ago. On examination, the girl is in obvious discomfort, and although her forearm is moderately swollen, the skin is grossly intact. The forearm is deformed, and she is exquisitely tender to palpation toward the distal aspect. When asked, she will gingerly flex and extend her wrist. However, she will not supinate or pronate. The radial pulse is palpable, and brisk capillary refill is noted. She has grossly intact neurologic sensation and motor function. Radiographs are obtained ( Figure 14–1 ).

► What is the most likely diagnosis?

► What is the best treatment of this injury?

A

    B

Figure 14–1. (A) AP and ( B) lateral radiographs of a left forearm in a skeletally immature individual.

(Courtesy of Andrew J. Rosenbaum, MD)

ANSWER TO CASE 14:

Pediatric Both Bone Forearm Fracture                              

Summary: A right-hand-dominant 8-year-old girl presents with left forearm pain and deformity after landing on her outstretched left hand following a fall from a trampoline. Motor, sensory, and vascular exams are all normal. Radiographs reveal distal one-third diaphyseal fractures of her radius and ulna.

• Most likely diagnosis: Both bone forearm fracture (BBFF).
• Preferred treatment: Closed reduction and application of a long-arm cast.

ANALYSIS

Objectives

1. Understand the mechanism of injury associated with fractures of both the radius and ulna in children.
2. Know the proper radiographic imaging to obtain in the setting of a BBFF.
3. Know the indications for both nonoperative and operative treatment of pediatric BBFF.

Considerations

This 8-year-old girl presents with pain and deformity of her left forearm after falling onto her outstretched hand while playing on a trampoline. Her severe pain and obvious deformity must make the clinician very suspicious for a fracture, specifically a BBFF. An additional physical examination finding that also supports this diagnosis is her refusal to supinate and pronate her forearm. Fortunately, this is not an open injury and she is neurovascularly intact. Plain radiographs of the forearm confirm a BBFF. The images obtained include views of both the wrist and elbow on the anteroposterior (AP) view, which do not appear to be fractured. Ideally these joints would also be included on the lateral radiograph as well. Because the girl has no specific complaints or exam findings concerning for either a wrist or elbow injury, no further imaging of these joints is needed. Most pediatric forearm fractures, including the BBFF sustained by this girl, can be managed nonoperatively as a result of the significant remodeling potential of children’s bones. In this case, closed reduction and long-arm casting is the treatment of choice.

APPROACH TO:

Pediatric Both Bone Forearm Fracture                                             

DEFINITIONS

BOTH BONE FOREARM FRACTURE: A fracture involving both the radial and ulnar shafts. They are classified in a descriptive fashion, based on the level (distal, middle, proximal third) and the pattern (greenstick, plastic deformation, complete, comminuted).

GREENSTICK FRACTURE: A fracture in which partial bony continuity is preserved. In other words, a break that does not violate all cortices. Greenstick fractures are unique to children and can be thought of as an intermediate between a bending deformation of soft pediatric bone and a complete fracture.

CLINICAL APPROACH

Mechanism of Injury

Forearm fractures are the most common pediatric fractures associated with trampolines and the second most common fractures seen with falls from monkey bars (supracondylar fractures are first). It is usually a fall onto an outstretched hand that leads to a BBFF, with rotation influencing the location of the radius and ulna fractures. For example, when a fall is accompanied by minimal torsion or rotation, the fractures of the radius and ulna are likely to be at the same level. If the forearm is rotated during the injury, the radius and ulna usually fracture at different levels.

Classification

Classification is usually descriptive and based on the level of the fractures (distal, middle, proximal third) and the pattern (greenstick, plastic deformation, complete, comminuted). Many believe that the more proximal the forearm fracture, the more difficult it is to treat. Fracture pattern can also influence treatment options. While greenstick and complete fractures are usually amenable to closed reduction and casting, comminuted fractures in both the radius and ulna may require surgical plate fixation. A buckle fracture, which will look like a “speed bump,” never occurs in isolation in the shaft but may accompany plastic deformation or greenstick fractures. A radial or ulnar shaft buckle fracture, which may appear like a “speed bump” on radiographs, almost never occur in isolation. They are typically accompanied by plastic deformation or greenstick fractures in the other forearm bone.

Workup

Physical examination and plain radiographs (anteroposterior and lateral views) of the involved forearm comprise the initial workup. Dedicated x-rays of the wrist and elbow should be obtained only if clinical suspicion for injury at those joints exists. On examination, soft tissue integrity, areas of tenderness, and any deformity should be noted. Range of motion at both the elbow and wrist should be assessed, as should forearm supination and pronation. Motor, sensory, and vascular exams should also be performed. A useful way to evaluate motor function distal to the injury is by asking the patient to perform the hand gestures from the game “rock, paper, and scissors.” Median nerve function is observed via the “rock” gesture; radial nerve function via the “paper” gesture; and ulnar nerve function via the “scissor” gesture.

TREATMENT

Both nonoperative and operative interventions have the identical goal: to achieve healing within established anatomical and functional guidelines. In growing children, this must be done while taking into account the remodeling that occurs. Several mechanisms affect bone remodeling in children. The distal radial epiphysis will correct angular deformity at approximately 10 degrees per year, independent of age, as long as the physis remains open. As the bones lengthen through growth, remodeling will lead to decreased angulation. Bone remodeling also occurs through intramembranous apposition on the concave side and resorption on the convex side of bone. This is best accomplished in children, who inherently have thick periosteum. Of note, children older than 11 years are less effective at correcting bone angulation than younger children.

    Most pediatric both bone forearm fractures are amenable to nonoperative treatment with reduction, if displaced, and long-arm casting. Young children with less than 5 to 10 degrees of angulation do not require reduction. The following criteria serve as age-dependent guidelines:

• For ages < 6 years, up to 15 degrees of angulation and 5 degrees of rotation can be accepted.
• For ages 6 to 10 years old, less than 10 degrees of angulation is preferred, as is end-to-end apposition; bayonet apposition is not ideal but may be acceptable.
• For ages ê 12 years, no angulation or rotation can be accepted.
• For ages ê 6 years, rotational deformity is never acceptable.

    Long-arm casting of BBFFs includes placing a proper interosseous mold, supracondylar mold, and appropriate padding. A complete and proximal BBFF should be immobilized in supination. This position allows the distal forearm to align with the proximal fracture fragments, which have been pulled into supination by the now unopposed biceps and supinator muscles. Fractures of the middle third of the radius should be immobilized in neutral wrist rotation, since at this level, the supination forces on the proximal fragments are neutralized by the pronator teres that remains proximally attached. Fractures in the distal third should be immobilized in pronation to similarly neutralize the effect of the pronator quadratus distally. After acceptable reduction and application of a long-arm cast, the patient is followed with x-rays at 1- to 2-week intervals.

    When there is an open fracture or acceptable reduction cannot be achieved, open reduction and internal fixation, rather than casting, is the preferred treatment. Many operative techniques have been described and include plate fixation, flexible intramedullary stabilization, and percutaneous pinning.

COMPLICATIONS

Complications after treatment of BBFFs include redisplacement and loss of reduction (the most common short-term complication, typically secondary to inadequate cast molding), stiffness, refracture, malunion, delayed union/nonunion, radioulnar synostosis resulting in complete loss of forearm rotation; neurapraxia (median nerve most commonly), muscle and tendon entrapment, compartment syndrome, and infection.

COMPREHENSION QUESTIONS

14.1 An 8-year-old boy fell while riding his bike, landing on his outstretched right hand. Radiographs confirm a middle-third diaphyseal both bone forearm fracture with end-to-end cortical apposition and 12 degrees of dorsal angulation. What is the preferred method of treatment for this injury?

A. Percutaneous pinning of both the radius and ulna

B. Closed reduction and long-arm cast application in supination

C. Closed reduction and long-arm cast application in neutral

D. Short-arm cast application

14.2 Which of the following is most accurate regarding bone remodeling in children?

A. The distal radial epiphysis will correct angular deformity at approximately 20 degrees per year, independent of age, as long as the physis remains open.

B. As the bones lengthen through growth, remodeling will also occur and lead to decreased angulation.

C. Intramembranous apposition on the convex side and resorption on the concave side of bone lead to remodeling.

D. Children older than 11 years are more effective at correcting bone angulation than younger children.

14.3 A 13-year-old girl sustains a both bone forearm fracture after a fall. Which of the following statements is most accurate regarding the radiographic evaluation of anatomic forearm alignment after reduction?

A. On the AP radiograph, the ulnar styloid and the coronoid process are oriented 270 degrees apart.

B. On the AP radiograph, the radial styloid and tuberosity are oriented 180 degrees apart.

C. On the lateral radiograph, the ulnar styloid and the coronoid process are oriented 90 degrees apart.

D. On the AP radiograph, the radial styloid and tuberosity are oriented 90 degrees apart.

ANSWERS

14.1 C. A middle-third diaphyseal BBFF with 12 degrees of angulation in an 8-year-old is amenable to closed reduction and long-arm casting. In children 6 to 10 years old, less than 10 degrees of angulation is ideal and should be accomplished with closed reduction in this patient. The extremity should be immobilized in a neutral position via a long-arm cast, as the fracture is in the middle third.

14.2 B. As bones lengthen through growth, remodeling also occurs and leads to decreased angulation. Thus B is the correct answer. The distal radial epiphysis will correct angular deformity at approximately 10 degrees per year, not 20, as A states. Intramembranous apposition on the concave side and resorption on the convex side of bone lead to remodeling, the opposite of that stated in C. Lastly, children older than 11 years are less effective at correcting bone angulation than younger children, making D incorrect.

14.3 B. After proper reduction, the radial styloid and tuberosity are located 180 degrees apart. On lateral radiographs, the ulna styloid and the coronoid are 180 degrees apart.

    CLINICAL PEARLS    

► Classification of BBFFs is usually descriptive and based on the level of the fractures (distal, middle, proximal third) and the pattern (greenstick, plastic deformation, complete, comminuted). ► Ipsilateral wrist and elbow regions should be included on the standard forearm x-rays obtained when working up a BBFF. However, if clinical suspicion is high for additional injury to either of those joints, then dedicated wrist and elbow films must be obtained. ► Most pediatric both bone forearm fractures are amenable to nonoperative treatment with reduction, if displaced, and long-arm casting. ► The amount of angulation and rotation that can be tolerated is age dependent, with less tolerance with increasing age. ► When there is an open fracture or acceptable reduction cannot be achieved, open reduction and internal fixation, rather than casting, is the preferred treatment.

REFERENCES

Mehlman CT, Wall EJ. Injuries to the shafts of the radius and ulna. In: Beaty JH, Kasser JR, eds. Rockwood and Wilkins’ Fractures in Children . 6th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2006.

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