If an adequate closed reduction is achieved, cast treatment may be a reasonable option provided the fracture is carefully followed and that the reduction (“good alignment of the bones”) can be maintained. This is typically poorly tolerated by high level athletes, particularly in the dominant hand. However, because of the extension of this fracture into the joint and the significant deforming forces from muscles, worsening fracture step-off and displacement is often seen with closed treatment methods. Closed reduction (manipulation) and cast immobilization often leads to satisfactory short-term results without significant functional impairment. There is certainly no uniform consensus on what initial fracture treatment results in the best long term outcome. Much of the past scientific data on treatment is conflicting. Bennett first described the fracture that bears his name, many authors have advocated for different methods of Bennett’s Fracture treatment. Injury is most commonly seen in the dominant hand (2/3) and predominates in men at nearly a 10:1 ratio. This injury mechanism can be seen in boxing but is also commonly seen in sports such as football or rugby. The classic mechanism for injury that produces a Bennett fracture is an axially directed force (force applied to the end) of a partially flexed thumb metacarpal. Your treating physician will not only take careful note of the size and displacement of the fracture fragment, but also will evaluate for the presence of cartilage injury (the smooth tissue that lines the joint surfaces) on both the metacarpal and trapezium. If plain films still do not provide adequate evaluation of the fracture, CT scans can be obtained of the affected area. Additionally, a “prayer” view may provide a more focused view of the thumb metacarpal joint as well. Once appropriate suspicion for a fracture is present, standard posteroanterior, lateral, and oblique radiographs (x-rays) should be obtained. Active motion is limited because of pain. Athletes will have pain and swelling noted at the base of the thumb. The typical presentation is seen in an athlete with a recent history of an axial load to a flexed thumb such as a fall onto an outstretched hand. Furthermore, the adductor pollicus (ADP) attaches near the metacarpal head and pulls the distal fragment towards the palm. The distal fragment is displaced proximally, radial (towards the thumb side), and dorsal (behind the rest of the hand) by the pull of the abductor pollicus longus (APL) muscle. However, the rest of the metacarpal fragment is subject to deforming forces that create a tendency toward further fracture displacement. This strong ligament functionally remains intact after a Bennett’s fracture and allows the articular fracture fragment to maintain its anatomic relationship with the trapezium. The volar oblique ligament connects the base of the thumb with the trapezium and is the primary soft-tissue stabilizer of the thumb CMC joint. In a Bennett’s fracture, the fracture begins at the volar (palm side), ulnar base of the thumb metacarpal and extends in an oblique fashion distally. This creates a complex joint that allows the thumb to have complex motion and to function as an opposable digit. The contour of the trapezium and thumb metacarpal base forms a saddle-joint and contributes significantly to the joint’s stability. It forms the thumb or first carpometacarpal (CMC) joint. The Bennett’s fracture occurs at the base of the thumb metacarpal (the longest bone in the thumb) where it articulates with one of the carpal (wrist) bones called the trapezium. Bennett’s early work on this injury, the fracture is still commonly known as a Bennett’s fracture. He went on to suggest that despite the relatively benign appearance of the fracture, prompt recognition and treatment is necessary to preserve function of this complex, highly mobile joint. In 1882, Edward Hallaran Bennett, M.D., an Irish surgeon, described five cases of an “intra-articular” fracture dislocation. This injury most often occurs in contact sports such as football, rugby, and boxing. A Bennett’s fracture is an intra-articular fracture, or one that extends into the joint between the metacarpal and wrist bone (“trapezium”). The Bennett’s fracture is the most common type of fracture to the thumb metacarpal base. Of these fractures of the thumb metacarpal, 80% occur at the base (the end closer to the wrist). Approximately ¼ of metacarpal fractures occur in the thumb metacarpal. Last Updated on Octoby The SportsMD Editorsįive bones (“ metacarpals”) are in the hand that connect the bones of the wrist (“carpus”) with those of the digits (“phalanges”).
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