Rockwood Children CH8

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SECTION TWO • Upper Extremity

D

C

Figure 8-27.  ( Continued ) C, D: Once length has been reestablished, the distal fragment is flexed into the correct position. Alignment is checked by determining the position of the fragments with the thumb and forefingers of each hand.

and has been associated with greater need for assistance with activities of daily living, as well as more days of school missed. 207 Prior randomized controlled trials have demonstrated that short-arm casts are as effective at maintaining reduction as long- arm casts, provided that acceptable alignment is achieved and an appropriate cast mold is applied. 20,207 A recent meta-analysis pooling the results of over 300 study subjects has further sup- ported these findings. 93 Perhaps more important than the length of the cast applied is the cast mold applied at the level of the fracture (Fig. 8-28). Appropriate use of three-point molds will assist in mainte- nance of alignment in bending injuries. Similarly, application of

interosseous mold will help to maintain interosseous space between the radius and ulna as well as coronal plane alignment. A host of radiographic indices have been proposed to quantify and characterize the quality of the cast mold, including the cast index, three-point index, gap index, padding index, Canterbury index, and second metacarpal/distal radius angle (Fig. 8-29). 10,57,90,164 Although the cast index is easily calculated and perhaps most widely utilized, some authorities tout the three-point index as the preferred index for this assessment and prediction of redisplacement. 48 Complete fractures of the distal radius have a higher rate of loss of reduction after closed treatment than do incomplete fractures (Fig. 8-30). Indeed, prior investigations have demon- strated that 20% to 30% of patients will have radiographic loss of reduction following closed reduction and casting of displaced distal radius fractures. Risk factors for loss of reduction include greater initial fracture displacement and/or comminution, sub- optimal reduction, suboptimal cast mold, and associated distal ulna fractures. 6,10,48,57,90,141,164 Given the risk of radiographic loss of reduction, serial radio- graphs are recommended in the early postinjury period. Weekly radiographs are obtained in the first 2 to 3 weeks following reduction to confirm adequacy of alignment. Failure to identify and correct malalignment in the early postinjury period may lead to malunion and subsequent clinical loss of motion and upper limb function. Malalignment of fractures during the development of soft tissue callus before bridging ossification (injury to 2 to 3 weeks after reduction) often can be realigned using cast wedging (Fig. 8-31). 14,17,36,85,101,191,208 Recently, this technique has been utilized less frequently given the advances in surgical manage- ment of fractures. Authors have advocated opening wedges, closing wedges, as well as a combination of each of these approaches. Most commonly we use open wedge techniques as closing wedges have the potential for pinching of the skin and causing accumulation of cast padding at the wedge site which may cause skin breakdown. 85,101 In addition, closing wedges also may shorten and reduce the volume of the cast thus decreasing fracture stability. There have been multiple

Figure 8-28.  Three-point molding. Top: Three-point molding for dorsally angulated (apex volar) fractures, with the proximal and distal points on the dorsal aspect of the cast and the middle point on the volar aspect just proximal to the fracture site. Bottom: For volar angulated fractures, where the periosteum is intact volarly and disrupted on the dorsal surface, three-point molding is performed with the proximal and distal points on the volar surface of the cast and the middle point just proximal to the fracture site on the dorsal aspect of the cast.