Acute fractures to the proximal fifth metatarsal bone: development of classification and treatment recommendations based on the current evidence.

Fractures to the proximal fifth metatarsal bone are among the most frequent injuries to the foot. Various classifications intend to distinguish different fracture entities in regard to prognosis and treatment. The most commonly used classification by Lawrence and Botte delineates three fracture zones and gives treatment recommendations based on retrospective case series. Aim of our study was to critically review the literature and reevaluate the classification and treatment recommendations based on the highest level of evidence available. We performed a systematic literature search in Medline, Embase and Cochrane library and identified six prospective trials either comparing the same treatment for different fracture entities or different treatment strategies for the same fracture entity. The studies reveal that all "tuberosity avulsion fractures" (Zone 1, according to Lawrence and Botte) heal well using functional treatment. Even multifragmentary, displaced and intraarticular fractures in Zone 1 give comparable good results. Treatment with a short leg cast leads to a significant delay in return to preinjury level when compared to functional treatment. "Jones' fractures" (Zone 2) also demonstrate good to excellent results and complete bone healing when treated functionally. In contrast, "diaphyseal stress fractures" (Zone 3) at the distal limit of the fourth-fifth intermetatarsal articulation and just distally feature a significantly higher rate of treatment failure when treated non-operatively in a non-weight bearing short leg cast. Early intramedullary screw fixation leads to a significantly shorter time to bone healing and return to sport. In conclusion, acute fractures to the proximal fifth metatarsal bone should be classified into two entities only: First, metaphyseal fractures not extending beyond the distal end of the fourth-fifth intermetatarsal articulation, as these fractures, regardless the number of fragments, displacement and intraarticular involvement, should be treated functionally. Second, meta-diaphyseal fractures located at the distal end of the fourth-fifth intermetatarsal articulation or just distally, as these fractures require early intramedullary screw fixation.