A case report: Distal humeral diaphyseal fracture in a child.

RATIONALE: Distal humeral diaphyseal fractures are much less common than supracondylar humeral fractures. The triangular shape and thinner periosteum in the diaphyseal region than in the supracondylar region of the distal diaphysis makes the treatment of diaphyseal fractures difficult. Nonoperative treatment for this fracture is challenging and troublesome; thus, open reduction and internal fixation (OR/IF) is generally recommended. PATIENT CONCERNS: We herein report a distal humeral diaphyseal fracture in a child. A 6-year-old boy fell from a chair, injuring his left elbow. Radiographs were performed at a local clinic. DIAGNOSIS: Unstable diaphyseal shaft fracture of the left humerus.
INTERVENTIONS: Because of the severe displacement of the fracture and difficulty maintaining alignment for reduction, we performed OR/IF using an anterior mini-incision approach on the cubital skin line under general anesthesia. OUTCOMES: Displacement of the fracture was reduced easily, and stable fixation was achieved using percutaneous intramedullary Kirschner wires. After immobilization with a long-arm cast for 4 weeks, the cast was removed and range-of-motion exercises were encouraged. At 9 months postoperatively, the range of elbow motion was 0° to 135°. Baumann angle and the carrying angle were 62° and 17°, respectively. According to Flynn criteria, the result was excellent. LESSONS: OR/IF using the herein-described cubital anterior approach seems to be a safe and easily performed procedure for distal humeral diaphyseal fractures, and percutaneous intramedullary Kirschner wires provide reliable fixation in such cases.

Introduction

Distal humeral diaphyseal fractures are much less common than supracondylar humeral fractures. To the best of our knowledge, only a few cases of distal humeral diaphyseal fractures have been reported in the English literature.[ The authors of these reports stated that the triangular shape and thinner periosteum in the diaphyseal region than in the supracondylar region make closed reduction difficult.[ Nonoperative treatment for this fracture is therefore challenging and troublesome, and open reduction and internal fixation (OR/IF) is generally recommended.[ We previously reported the short-term outcome of a distal humeral diaphyseal fracture in a Japanese literature.[ In the present report, we describe the mid-term outcome of such a fracture in a 6-year-old boy.

Case presentation

A 6-year-old boy fell from a chair and injured his left elbow. A hanging cast was applied at a local clinic, and he presented to our hospital 2 days after the injury. Upon presentation, he complained of pain in the left humerus, but no neurological findings or impediment to blood flow was found on physical examination. Plain radiographs showed a displaced fracture at the distal humeral diaphysis of the left humerus. The fracture was not reduced and was remarkably unstable (Fig. 1). Magnetic resonance imaging showed a vertical fracture line extending into the lateral humeral condylar physis of the distal humerus (Fig. 2). Surgical treatment was required because of the severe displacement of the fracture and difficulty maintaining alignment for reduction. Informed consent was obtained from the patient and his parents for surgery and publication of this case.

Figure 1

Preoperative roentgenogram of the left upper extremity. Radiographs showed severe displacement of the distal humeral diaphyseal fracture.

Figure 2

Preoperative (A) anteroposterior magnetic resonance image of the left upper extremity and (B) lateral magnetic resonance image of the left elbow. A vertical fracture line was seen extending into the lateral humeral condylar physis of the distal humerus.

With the patient under general anesthesia, closed reduction of the distal humeral fracture was initially attempted under fluoroscopic control. However, this could not be achieved with anatomic reduction because the fracture was extremely unstable and irreducible. We made an anterior mini-incision on the cubital skin line and removed the brachial muscle, which was preventing reduction in the fracture part. After removal of the brachial muscle, the displacement of the fracture was easily reduced and the alignment could be maintained by thumb compression (Fig. 3). Percutaneous intramedullary fixation was performed using 1.5-mm Kirschner wires, inserted from the humeral distal metaphysis (Fig. 4). Once the distal humeral diaphyseal fracture was stabilized using the intramedullary wires, the displacement could be reduced and stable fixation was achieved to maintain the alignment of the left humerus. We used a long-arm fiberglass cast to immobilize the left upper extremity for 4 weeks postoperatively. Thereafter, the cast and Kirschner wires were removed, and range-of-motion exercises were encouraged. At the final follow-up, 32 months postoperatively, plain radiographs showed adequate healing without any deformity of the elbow (Fig. 5). The range of elbow motion was 0° to 135°, which was equal to the contralateral side. According to Flynn criteria,[ the ultimate outcome was excellent (Fig. 6).

Figure 3

Open reduction procedure. (A and B) The displacement of the fracture was easily reduced by open reduction using an anterior mini-incision and thumb compression.

Figure 4

Early postoperative roentgenograms of the left elbow. (A and B) Percutaneous intramedullary fixation provided stability of the distal humeral diaphyseal fracture.

Figure 5

Postoperative roentgenograms of the left elbow at 32 months postoperatively. (A and B) Radiographs showed adequate healing without any deformity of the elbow.

Figure 6

Postoperative photographs of left elbow at 32 months postoperatively. The range of motion was 0° to 135°, which was equal to the contralateral side. According to the Flynn criteria, this result was excellent. In addition, the surgical scar result was cosmetically excellent.

Discussion

Sanders et al[ reported that the distal humeral diaphysis, sometimes called the metaphyseal–diaphyseal junction, is more triangular in shape and has a thinner periosteum than the supracondylar humerus, which makes fractures of the distal humeral diaphyseal less stable than supracondylar fractures. Moreover, diaphyseal fractures heal more slowly than do metaphyseal fractures, thus requiring longer immobilization.[ Closed treatment of distal humeral diaphyseal fractures is possible; however, these fractures tend to result in cubitus varus deformity,[ which may be cosmetically unacceptable. Particularly, in more distal fractures, the varus deformity may be more likely to occur. In addition, significant remodeling may not occur because ≤20% humeral growth occurs distally.[

With respect to maintenance of the reduced position, Kwon et al[ reported that humeral distal diaphyseal fractures have a tendency toward rotation deformity accompanying pronation or supination of the forearm because the humeral distal metaphysis is the origin of the wrist extensor group: the brachioradialis muscle, pronator teres muscle, and anconeus muscle.

Because humeral distal diaphyseal fractures are extremely unstable, it is difficult to reduce them while maintaining anatomical alignment. Therefore, open reduction is usually recommended.[

With respect to fracture fixation, cross-pinning would be ideal to achieve rigid fixation. However, because distal diaphyseal fractures are more proximal than supracondylar fractures, it is difficult to access the diaphysis through the fracture.[ In such cases, intramedullary fixation performed by passing through the fracture site from the lateral and medial condyles is used to provide reliable stability.[

In children, rapid bone healing is usually achieved by reliable fracture stabilization and 4 weeks of long-arm cast immobilization pending radiographic evidence of adequate bony callus formation. Accurate reduction is a key in the treatment of distal humeral diaphyseal fractures in children.

In the present case, closed reduction was unsuccessful, and open reduction therefore became inevitable. An anterior approach[ using a mini-incision on the cubital skin line allowed anatomical reduction to be easily achieved and provided a cosmetically excellent result with respect to the surgical scar. In addition, percutaneous intramedullary Kirschner wires provide reliable fixation for this fracture in children.

Conclusion

Nonoperative treatment can make it difficult to achieve reduction and maintain alignment of distal humeral diaphyseal fractures. Thus, OR/IF should be the treatment of choice for this fracture. OR/IF using a cubital anterior approach is a safe and easily performed procedure for this fracture, and percutaneous intramedullary Kirschner wires can provide reliable fixation.