Can Fifth Metatarsal Morphology Predict Proximal Fifth Metatarsal Fracture Risk? A Radiographic Analysis of National Football League Players

Abstract

Category: Sports. Introduction/Purpose: Fractures of the proximal fifth metatarsal are one of the most common foot injuries in athletes. Unfortunately, optimal treatment is often challenging, as the repetitive stresses endured by the fifth metatarsal can lead to delayed union and refracture following treatment. We therefore performed a radiographic analysis of fifth metatarsal morphology and foot type in NFL players, in search of morphologic risk factors for these injuries. Methods: NFL players treated by the senior authors between 1992 and 2012, as well as participants in the 2014 NFL Combine were evaluated. A total of 96 feet (51 athletes) were included. Fractures were present in 15 of the feet. Two reviewers assessed fifth metatarsal morphology and foot type on anteroposterior (AP), lateral and oblique radiographs, after receiving measurement training by the senior authors. Table 1 lists the specific parameters studied. Reviewers’ measurements were averaged, as were those from the radiographic series for each athlete. Differences in foot type and metatarsal morphology between athletes with and without fractures were determined via Student’s t-test analysis. Results: Athletes had an average height of 6’2” (range 5’8” to 6’8”) ft’in”, weight of 251 (range 184 to 336) lbs, and age of 22.4 (range 21.0 to 26.0) years. Reviewers’ inter-observer reliability was generally good to very good. On AP radiographs, statistically significant differences in apex medullary canal width, 4-5 intermetatarsal angle, 5th metatarsal angle, and talar head uncovering were observed between fractured and non-fractured feet (p=0.001, 0.003, 0.004, 0.008, respectively; Table 1). On lateral radiographs, statistically significant differences in the 5th metatarsal length, distance to apex, apex height, 5th metatarsal angle, and talocalcaneal angle were observed between fractured and non-fractured feet (p=0.04, 0.01, 0.02, 0.01, 0.01, respectively; Table 1). On oblique radiographs, a statistically significant difference was observed in apex height between fractured and non-fractured feet (p=0.002; Table 1). Conclusion: This investigation elucidates the relationship between fifth metatarsal morphology, foot type and proximal fifth metatarsal fractures. Specifically, individuals with long, straight and narrow fifth metatarsals, with an adducted forefoot are most at risk. Given athletes’ predisposition to refracture and nonunion following treatment of proximal fifth metatarsal fractures, which is at times career threatening, we believe that these findings are clinically relevant. With such insight, attempts at fracture prevention can be implemented via footwear modifications, orthoses, and off-loading braces that account for those aforementioned morphologic attributes that place athletes at-risk. Admittedly, future research must evaluate the utility of such interventions.