Non randomised retrospective study of jones fractures treated by conservative treatment

Abstract

Fractures of the metatarsal bones are among the most frequent injuries of the foot (>50%) and represent 5–6% of all fractures seen in emergency departments [1-5]. Multiple classification systems, over-complicating the issue, have been introduced to distinguish the different proximal fracture types of the fifth metatarsal bone (5MTB) [6-9]. These are considered complicated injuries due to the peculiar blood supply of this area and the multiple anatomical structures that insert in the proximal epiphysis of the 5MTB (Figure 1) [10]. Torg proposed to divide the 5MTB into four zones based on common fracture lines, and sub-classifying them into acute, delayed or non-union [11]. At present, the simplified three-part classification proposed by Lawrence and Botte is the most commonly used [12], distinguishing between tuberosity avulsion fractures, Type-1 (Zone1); fractures at the metaphyseal-diaphyseal junction, called Jones fractures, Type-2 (Zone-2); and shaft stress fractures Type-3 (Zone3). However, it is not widely accepted because many fracture lines lie between these zones [13-18]. In 2012, Polzer stated that non-operative treatment is indicated for metaphyseal fractures and surgical fixation for metadiaphyseal fractures, although the exact borderline between these groups remains unclear [19]. More recently, in 2014, Mehlhorn et al. proposed a new radiographic classification of tuberosity avulsion fractures (Zone-1), identifying 3 fracture groups at risk of secondary displacement: fractures entering in the lateral third of the 5MTB joint, fractures occurring in the middle third, and fractures in the medial third. They further divided them into two categories: non-displaced or displaced with a fracture-step-off >2 mm [20]. Although Mehlhorn et al. evaluated the risk of secondary displacement, they did not evaluate patient clinical outcomes, neither excluded from their classification the Type-2 and 3 fractures as described by Lawrence and Botte [12]. Management of 5MTB fractures can be challenging and is a matter of discussion in the orthopaedic community. There is little data available concerning the different fracture patterns of Zone-1, so we sought to categorize Type-1 fractures in this study to increase awareness of the typical patterns of tuberosity injuries [19,20]. Therefore, the purpose of this observational, retrospective, nonrandomized study, performed on a consecutive series of patients with diagnosis of acute, minimally displaced, proximal fracture of 5MTB, was to evaluate radiographic and clinical early outcomes in relation to the different fracture patterns, including sub-types-1, after conservative management without weightbearing restriction by a below-knee walking cast or a functional elasticated bandage with the support of a flat hard-soled shoe.