A mold is applied to keep the thumb abducted, as described in the Bennett fracture daily use cast ( Figure 3c). This is then covered with cast padding and fiberglass, using extra caution when casting the first web space to avoid bunching the materials ( Figures 3a and and3b). A stockinette is applied over the wrist and thumb. The cast designed for game day use is a much shorter thumb spica cast that is applied using similar techniques. (b) Thumb metacarpal shaft fracture: 3-point pressure is applied dorsally over the midshaft and volarly over the metacarpal head to resist the apex dorsal deformity. (a) Bennett fracture: Thumb is in abduction with ulnar pressure applied at the lateral base of the thumb carpometacarpal joint. Note: Size of arrows indicates relative force applied. This everyday cast should be worn for a minimum of 4 weeks. A mold is applied by abducting the thumb and placing pressure over the lateral aspect of the CMC joint ( Figure 2a). The cast designed for daily use is a typical thumb spica cast that extends beyond the wrist but allows for motion at the MCP joints of the fingers. If nonoperative treatment is chosen, the fracture must become “sticky” with early healing before the 2-cast system is employed for definitive treatment. The clinician applying the cast must evaluate the fracture alignment to decide whether the athlete would benefit from immediate fixation or whether bony healing will likely be satisfactory through immobilization alone. Especially in cases of unstable fractures, it may be necessary to operatively fix the injury in the acute setting rather than risking malunion. In some cases, it may be technically difficult to properly stabilize a Bennett fracture using a cast. Once the fracture is reduced, a long thumb spica cast is applied. When a Bennett fracture occurs during active gameplay, a neoprene thumb spica sleeve may be used for short-term stabilization. 6 Nonoperative treatment can be used if reduction of the CMC joint can be maintained. 16 Occasionally, a computed tomography (CT) scan is needed to better appreciate fracture pattern and fragment displacement. 4 Plain film radiographs in the posterioanterior (PA), lateral, and oblique views diagnose metacarpal fractures. 19 After a blow to the hand, swelling and tenderness over the carpometacarpal joint of the thumb can indicate fracture. The oblique posteromedial ligament retains the smaller fragment’s attachment to the trapezium.īecause of the location, Bennett fractures can be less visually obvious than other metacarpal fractures, and distortion of the joint and metacarpal may not be evident on gross inspection. The avulsion fragment dislocates at the carpometacarpal joint in a dorsal and radial manner due to the APL and proximally due to the medial thenar muscles. The base of the thumb metacarpal bone fractures, allowing the attachment of the abductor pollicis longus (APL) to displace the metacarpal fragment. 2 It should be noted that most athletic associations require any athlete who is medically cleared to participate in a sporting event while wearing a rigid cast or splint to have the entire area covered in no less than 0.5-inch-thick closed-cell slow recovery foam padding to protect both the injured athlete and opponents. In these cases, it is necessary to wait a minimum of 10 days after the injury for sufficient callus to be present before the fracture is stable enough to be removed from its original cast and placed in a temporary cast for game or practice. However, often it is not possible to take a cast on and off of an athlete in the acute setting without losing reduction. The goal is to maximize function for practice or game activity while maximizing protection and stability for nonsport activities. Depending on the type of upper extremity injury, select in-season athletes may be fit with 2 different types of casts or splints: 1 for everyday use and 1 for practice or gameplay.
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