Bennett Fracture

The findings include pain and swelling localized to the base of the thumb.

Standard hand radiographs include anteroposterior (AP), lateral, and oblique views.  Additional dedicated views of the thumb can be obtained to provide additional information about the injury, including Robert's view.[4] This view is a true AP view of the first carpal-metacarpal joint; it is performed with hyperpronation of the forearm having the dorsal aspect of the thumb placed against the radiographic plate and the x-ray beam directed 90 degrees to the plate. Another view is the Bett's view[4], which is obtained with the palm overpronated 20 degrees from flat against the radiograph plate and the beam directed 15 degrees proximal to distal. Stress radiographs can also be performed by pressing the radial aspect of the thumbs together on an AP view, which may demonstrate subluxation of the metacarpal base radially relative to the trapezium on the symptomatic side.

Based upon the radiographic appearance, Gredda classified Bennett fractures into three types, with type 1 being a fracture with a single ulnar fragment and subluxation of the metacarpal base, type 2 an impaction fracture without subluxation of the first metacarpal, and type 3 an injury with a small ulnar avulsion fragment in association with metacarpal dislocation.[5]

Proper reduction requires traction in an axial direction with palmar abduction, and pronation while applying external pressure over the first metacarpal base.[4] Thumb extension (known as the hitchhiker position) has been shown to cause fracture displacement and should be avoided.[1]

In the initial article by Bennett, he described the treatment of these fractures with closed reduction and splinting, which remained the preferred method of treatment until the 1970s.[6][7] Historical reports have shown good outcomes with this treatment, although more recent studies have shown poor outcomes when treating these fractures with casting alone.[8] Surgical treatment of Bennett fractures is varied but generally consists of either closed reduction with percutaneous pinning or open reduction with either pins or interfragmentary screws. All methods of fixation have been shown to be effective in case reviews and series. Treating with closed reduction with intermetacarpal fixation from the first to the second metacarpal and/or to the trapezium is usually effective in reducing the first metacarpal shaft subluxation. If it is decided to treat this fracture with open reduction, it is most commonly performed through a Wagner incision.[4] The decision to treat these fractures with either open reduction or closed reduction is still a matter of debate.

There is a debate in the literature regarding the amount of articular step-off at the fracture site that is acceptable in the nonathlete populations. Some authors have found no correlation between the quality of articular reduction and radiographic or subjective outcomes,[9][10] while biomechanical studies have demonstrated that 2 mm of persistent articular surface step-off does not alter the contact pressures at the location of the step off.[11]  It is therefore concluded that bony apposition of the fragments within 2 mm and the correction of any joint subluxation will be tolerated without increasing the risk of posttraumatic arthritis. Despite is biomechanical evidence suggesting good outcomes, many clinical studies have suggested that anatomic reduction is preferred.[7]

Rolando fracture which is a comminuted fracture at the base of the first metacarpal with a maintained volar carpal ligament, preventing displacement of the volar fragment.

The range of motion exercises may begin 5 to 10 days post screw fixation and after four weeks after pinning (after the pins are removed).[12] Long-term outcomes based on the study of Kjaer-Petersen which reviewed 41 Bennett fractures note that based on the quality of the fracture reduction. Eighty-six percent of patients with an anatomic reduction (less than 1 mm step off) had no residual symptoms, where only 46% of patients with good or poor reduction (greater than 1 mm step off) remained asymptomatic.[6]

Definitive treatment algorithms are lacking due to the small number of patients that are encountered with this fracture, lack of long-term imaging follow up, and lack of randomized prospective data.

• Despite a relatively simple appearance on radiographs, Bennett fractures are considered unstable.
• In evaluating and treating these fractures positioning the patient with thumb extension (hitchhikers position) should be avoided as this will cause further fracture displacement.
• Favorable long-term outcomes are based upon the degree of anatomic reduction with most patients having less than 1 mm articular surface step off having no residual symptoms.

The management of Bennet fracture is complex and best done with an interprofessional team that includes a hand surgeon or orthopedic surgeon, specialty care nurse, and physical therapist. When the fracture is encountered by the emergency department physician and nurse practitioner, it is important to refer the patient promptly to a hand surgeon. Poorly treated bennet fracture has very high morbidity. Even after adequate treatment, extensive rehabilitation is required. An orthopedic nurse provides patient and family education, assists with referrals, and provides status updates to the team. The outcomes for Bennet fracture are guarded.[13][14] [Level 5]