Rockwood Children CH8

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SECTION TWO • Upper Extremity

forearm. 204 The growth discrepancy between forearms in most patients is minor and does not require treatment. However, this is not the case for a patient with an arrest at a very young age, for whom complicated decisions regarding forearm lengthening need to occur. If a radial growth arrest occurs associated with a radial physeal stress fracture, treatment depends on the degree of deformity and the patient’s symptoms. Physeal bar resection often is not possible because the arrest is usually too diffuse in stress injuries. If there is no significant ulnar overgrowth, a distal ulnar epiphysiodesis will prevent the development of an ulnocarpal impaction syndrome. For ulnar overgrowth and ulnocarpal pain, an ulnar shortening osteotomy is indicated. Techniques include transverse, oblique, and Z-shortening oste- otomies. Transverse osteotomy has a higher risk of nonunion than either oblique or Z-shortening and should be avoided. Even when oblique or Z-shortenings are used, making the oste- otomy more distally in the metaphyseal region will lessen the risk of nonunion, owing to the more robust vascularity of the distal ulna. The status of the TFCC also should be evaluated by MRI or wrist arthroscopy. If there is an associated TFCC tear, it should be repaired as appropriate. Growth arrest of the distal radius after metaphyseal fracture is extremely rare with only five cases reported in the literature. Wilkins and O’Brien 211 proposed that these arrests may be in fractures that extend from the metaphysis to the physis. This coincides with a Peterson type I fracture (Fig. 8-57) 159 and in

essence is a physeal fracture. These fractures should be moni- tored for growth arrest. Both undergrowth and overgrowth of the distal radius after fracture were described by de Pablos. 46 The average difference in growth was 3 mm, with a range of − 5 to + 10 mm of growth dis- turbance compared with the contralateral radius. Maximal over- growth occurred in the 9- to 12-year-old age group. As long as the patient is asymptomatic, under- or overgrowth is not a prob- lem. If ulnocarpal impaction or DRUJ disruption occurs, then surgical rebalancing of the radius and ulna may be necessary. Physeal Arrest Distal Ulna Physeal growth arrest is frequent with distal ulnar physeal frac- tures (Fig. 8-58), occurring in 10% to 55% of patients. 81 It is unclear why the distal ulna has a higher incidence of growth arrest after fracture than does the radius. Ulnar growth arrest in a young child leads to relative radial overgrowth and bowing. The most common complication of distal ulnar physeal frac- tures is growth arrest. Golz et al. 81 described 18 such fractures, with growth arrest in 10%. If the patient is young enough, con- tinued growth of the radius will lead to deformity and dysfunc- tion. The distal ulnar aspect of the radial physis and epiphysis appears to be tethered by the foreshortened ulna (Fig. 8-59). The radial articular surface develops increased inclination toward the foreshortened ulna. This is similar to the deformity Peinado 154 created experimentally with arrest of the distal ulna

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Figure 8-57.  Physeal arrest in a Peterson type I fracture. A: Injury film showing what appears to be a benign metaphyseal fracture. Fracture line extends into the physis ( arrows ). B: Two years postinjury, a central arrest ( open arrow ) has developed, with resultant shortening of the radius. (Reprinted from Wilkins KE, ed. Operative Management of Upper Extremity Fractures in Children . Rosemont, IL: American Academy of Orthopaedic Surgeons; 1994:21, with permission.)