CONFOUNDING DIAGNOSES
Madelung's deformity This characteristic deformation of the distal radius growth plate demonstrates increased radial inclination and tilt, leading to dorsal ulna subluxation in combination with volar migration of the lunate. The condition is usually not related to trauma. Instead Madelung's deformity is often associated with dyschondrosteosis, or Leri-Weill syndrome. This inheritable skeletal dysplasia features shortened stature, a short forearm segment, and bilateral Madelung's deformity. Although all three characteristics were initially required to secure the diagnosis, Madelung's deformity alone is often able to identify Leri-Weill syndrome. The other criteria are now used to determine syndrome severity.15
The anatomical cause and deforming force on the distal radius comes from a fibrous band of tissue extending from the lunate to the volar/ulnar aspect of the radial epiphysis. This soft tissue tether, known as Vickers ligament, impedes radial-volar growth (Figure 6). If the ligament is released early, the physis can revert to normal growth and alignment16 (Figure 7). Confusion arises when asymptomatic patients with Madelung's deformity suffer a minor trauma that triggers pain. Subsequent radiographs draw attention to the dramatic radiographic findings, which are misinterpreted as a traumatic bone and growth plate injury.
Infection Another elusive differential diagnosis is infection, which usually manifests with pain. Pain without documented trauma is often categorized as growing pains in the absence of a better diagnosis. Osteomyelitis is rare in young, healthy children, but it is devastating if not recognized and treated early. As pointed out earlier, the growth plate is not wellvascularized. Where the vascular bed terminates near the physis, small capillary loops readily accumulate bacteria as a nidus for infection. Metaphyseal pain during palpation is a common initial manifestation of infection.
Very few studies have looked at children with infection. Tudisco and colleagues followed 26 cases of chronic osteomyelitis for more than 10 years.17 Patient ages ranged from 4 months to 15 years. Although most of the patients had documented trauma, wounds, or remote-site infections predisposing them to the onset of osteomyelitis, 10 patients had unknown etiologies. Only 11 of the patients presented with fever. All patients received antibiotics; 16 required curettage only four patients had resultant limb shortening and/or angular deformity. Another single-center retrospective review looked only at cases of acute neonatal osteomyelitis that eventually resulted in a growth disturbance.18 The investigators found six cases at sites other than the hip. Four cases involved the proximal humerus; one, the distal humerus; and one, the distal radius. Interestingly, the growth disturbances did not become apparent until around age 918 (Figure 8).
TREATMENT
Following trauma, any exquisite palpable pain that is focused over the growth plate should be assumed to result from a Salter-Harris type fracture until proven otherwise. Even if radiographic findings are normal, immobilization for a type I fracture is recommended. If there is any displacement of the fracture fragments, gentle closed reduction may be attempted, but repeated or aggressive manipulation should be avoided for fear of causing additional iatrogenic physeal injury. In the young child with substantial remaining growth, slight deformity can be corrected with osseous remodeling. Eighty percent of growth in the upper extremity occurs in the proximal humerus and the distal radius,19 so these areas accommodate well following deformity (the proximal humerus rarely needs to be reduced unless it is completely displaced7). Immobilization should include stabilization of the joint above and below the fracture for 3 to 4 weeks. Children usually do not require 4 to 6 weeks of immobilization because the rich vascularity and increased metabolic activity of the bone lead to accelerated unions. A standard practice is to have the patient follow up 1 week after cast application for repeat radiographs to ensure no loss of reduction. If adequate reduction cannot be attained or remains unstable, then operative fixation should be considered to restore stability and anatomic alignment. Type III and IV fractures are generally treated with percutaneous fixation to address articular involvement. The goal is to realign the physis and restore joint congruity. Postoperative cast immobilization is continued for 4 to 6 weeks.
SEQUELAE
Predicting adverse results from an injury to the physis is difficult, but making the diagnosis, minimizing further trauma, initiating the appropriate treatment, and having extensive followup visits can improve outcomes. The patient should return to the office 3 to 6 months after fracture management to ensure recovery of growth plate function. Radiographs are necessary to detect physeal closure and/or bony angulation. An MRI should be ordered if there is concern for a physeal bar, which represents premature closure of a physeal plate (Figure 9). Treatment hinges on the location and site of the bar. Peripheral bars create angular growth deformities, whereas central bars result in shortening over time. If the bar comprises less than 50% of the cross-sectional area of the entire physis and substantial skeletal growth remains, resection of the bar and interpositional fat grafting can be prudent. If the bar is greater than 50% of the physis, then complete closure may be considered to prevent further deformity.20
If a notable deformity in length or angulation does result, surgical management may be indicated, especially if there is pain or loss of motion. Performing an epiphysiodesis on the adjacent growth plate in the forearm can keep a proportional relationship between the two bones. When length cannot be regained through manipulation of remaining growth, bony lengthening via distraction osteogenesis is required. In this procedure, an acute angular osteotomy to correct any angular deformity is followed by application of an external fixator device to lengthen the bone. The rate of lengthening is 1 mm per day until the appropriate length is attained. About 6 cm of lengthening is usually attempted in a single procedure, although additional procedures can be performed later. The fixator usually needs to remain in place for 3 to 6 months or until there is adequate consolidation of bone in the defect. An example of lengthening is seen in Figure 10.
CONCLUSION
The rate of injury is high in the upper extremity, specifically in the hand, distal radius, and distal humerus. Diligence is necessary to recognize and manage growth plate injuries. A thorough knowledge of the radiographic findings and clues to injury and comprehension of the patterns of pediatric development will help ensure accurate diagnosis and establish treatment. MRI is the best advanced imaging study if radiography does not define the fracture well. Most fractures require simple immobilization unless they are displaced, unstable, or intra-articular. Regular follow-up appointments are critical to identify growth disturbances, allow early treatment, and minimize poor outcomes. JAAPA
Jason Smith works in pediatric orthopedics at Shriners Hospital for Children in Philadelphia, Pennsylvania. Scott Kozin is director of Hand and Upper Extremity Surgery at Shriners Hospital for Children in Philadelphia. The authors have indicated no relationships to disclose relating to the content of this article.
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