In general, metatarsal fractures are one of the ten most common skeletal fractures in adults [2]. The majority of these foot injuries affect the proximal fifth metatarsal bone [1, 3]. Treatment recommendations were derived depending on different fracture entities. In the current literature there is still critical discourse whether operative or conservative treatment of fractures to the proximal fifth metatarsal bone is superior [10]. Therefore, the aim of the presented study was to provide further evidence for treatment recommendations by analyzing the functional outcome following operative as well as conservative treatment of fractures to the fifth metatarsal bone.
Overall, the functional outcome of 103 patients suffering from fifth metatarsal bone fractures was assessed. The majority of the patients were female (61%) and on average older than the enrolled male patients. Epidemiological studies of metatarsal fractures also demonstrated a similar age and gender distribution with peak incidences in women around the age or older than 50 years [3, 4].
The functional outcome of L&B type I fractures was satisfactory with a median FAOS score of 91 following a nonoperative treatment (n = 10). This is in accordance with other studies advocating a conservative treatment for this fracture type to the proximal fifth metatarsal bone [12, 18, 19]. Outcome was assessed with the Visual Analogue Scale Foot and Ankle Questionnaire (VAS FA) and reported as good to excellent following conservative treatment [19, 20]. The VAS FA is a subjective patient reported score based on 20 questions [21]. In contrast to the FAOS some subscales are underrepresented or missing [17]. The type of conservative treatment included a short walking boot/cast and crutches for 5 weeks or a double-layered elasticated bandage/below the knee-walking cast for 4 weeks [19, 20]. Patients were not advised to partially weight bear and in some cases only received a symptomatic treatment without immobilization. Comparing the 1 year results of Shahid et al. with the presented findings, the long-term outcome after conservative treatment seems to be independent of the treatment protocol [20]. The advantage of a functional treatment with full weight bearing is an early-return-to-work and can be satisfactory employed, independent of displacement, articular involvement and comminution [11, 12].
Patients with an L&B type II fracture presented with a FAOS score of 91 a very good functional outcome. In the analyzed patient cohort conservative management (FAOS = 91) was equivalent in comparison to operative treatment (FAOS = 89) regarding the functional score. Despite some studies supporting surgery in these kind of fractures [14, 15, 22], there is growing evidence in the literature that conservative treatment results in excellent functional outcome [12, 13, 23]. The discrepancies might be due to inconsistent definition of fracture types among the studies since exact fracture location is decisive for prognosis. Following the classification of Dameron diaphyseal stress fractures, distal to the intermetatarsal joint, are so-called ‘Jones fractures’ (L&B type III) [5]. According to Lawrence and Botte ‘Jones fractures’ are located at the intermetatarsal joint (L&B type II) [8]. These inconsistencies regarding the classification systems can lead to inconclusive results in meta-analysis.
The presented results of L&B type I and II fractures strongly support the findings of Polzer et al. and their derived terminology combining type I and type II fractures in ‘epi-metaphyseal’ (L&B type I and II) and metaphyseal (L&B type III) fractures, since they show similar prognosis following operative and nonoperative treatment [9].
Patients with L&B type III fractures presented an overall FAOS score of 93 and the treatment in most cases was operatively. Surgically treated patients tended to have a better functional outcome in comparison to conservative treatment without reaching level of significance. This is in line with other studies recommending operative treatment for these fracture types to the fifth metatarsal bone [14, 16]. In a systematic review Roche et al. concluded, that nonoperative treatment is likely to lead to a higher failure rate than early surgical intervention in L&B type III fractures [14]. In a randomized control trial Mologne et al. demonstrated that screw osteosynthesis lead to a significant lower failure rate in comparison to immobilization in a short leg cast [16]. Due to the different healing progress following operative and nonoperative treatment, Polzer et al. concluded that fractures to the proximal fifth metatarsal bone should be classified as ‘epi-metaphyseal’ and metaphyseal [9]. Looking at the anatomy, this division into two zones follows the watershed line of blood supply of the proximal fifth metatarsal bone. Proximal to this watershed line (L&B type I and II) there is a rich intraosseous blood supply by numerous vessels of the lateral tarsal artery penetrating the non-articular surfaces of the tuberosity. The metaphyseal zone (L&B type III) is supplied by retrograde branches of a discrete nutrient artery [24, 25]. This results in a zone of relative lack of blood supply around this watershed line contributing to a delayed union or nonunion following trauma [9, 24, 25].
In the analyzed study age did not affect the functional outcome, which is in line with previous published studies showing no significant influence of patient age on the functional outcome [12, 13, 26].
Limitations of the study are the retrospective design and small number of patients in certain subgroups. Furthermore, long-term clinical and radiological results were not part of the study and thus the revision rate needs to be interpreted with caution. But to the best of our knowledge, the presented work reports about the largest patient population suffering from fractures to the fifth metatarsal bone using a self-reported patient outcome measurement questionnaire to assess and analyze functional outcome.
