Epidemiology of metatarsal fractures in Shropshire 2021-2024 (2024)

Type of publication:
Conference abstract

*Mark Garton, *Jenni Rowlands, *Richard Roach

Abstract submitted to Bone Research Conference, 2024

Background: Metatarsal fractures are common and disabling fractures, frequently triggered by low-energy injuries, or less often by repetitive loading. ‘Atypical’ metatarsal fractures have also been reported during prolonged anti-resorptive therapy, but a causal relationship remains speculative. Despite their clinical and economic importance, the epidemiology of metatarsal fractures remains poorly understood. We present a detailed service evaluation of radiologically-confirmed metatarsal fractures identified within Shropshire, over a three-year period. Methods: Radiology reports for all adults (≥18 years) attending hospital or community radiology departments between May 2020 and April 2023, were searched electronically using the terms ‘metatarsal’ AND ‘fracture’. All distinct patient episodes with ≥1 confirmed metatarsal fracture were identified for further analysis, and all duplicates were excluded. Age at fracture, sex, fracture type/distribution and mechanism of injury (where known) was recorded. Age- and sex-specific fracture rates were estimated by decade of life, using contemporaneous demographic data. Results: 1121 (758 female) patient-episodes of metatarsal fracture were identified, comprising 312, 397 and 412 individuals in years 1-3 respectively. Mean (SD) age at fracture was 50.7 (18.9) years, with 961 (85.7%) metatarsal fractures occurring in isolation, most (n= 736) affecting the fifth metatarsal. Smaller numbers fractured two (n=72), three (n=63), or four (n=15) metatarsal bones. Most fractures (59%) affected the metatarsal base, and less often the shaft (26%), neck (12%) and head (3%). Fractures were most often oblique (n=410), transverse (n=359) or comminuted (n=120), and only 70 patients had stress fractures. Estimated trauma levels were low (n=632), moderate (n=109), high (n=43) and unknown (n=246), and inversion and falls-related injuries the most commonly reported mechanism. Estimated annual fracture rates per 100,000, increased from 105 among women aged 18-29 years to 153 aged 50-59 years, with a second peak of 142 aged 80-89 years. For men at the same time points, rates were 102, 40 and 31. Although numerically less frequent, metatarsal neck fractures showed the greatest sex difference, becoming exponentially more common in women with age, compared to a gradual age-related decline in men. Discussion: Metatarsal fractures are common, usually affecting the fifth metatarsal in isolation, and often caused by low energy injuries, as shown by previous authors. Lower incidence during Covid lockdown may be genuine or reflect reduced ascertainment. Our estimates of age- and sex-specific fracture rates suggest pronounced sex differences in metatarsal fracture rates with age, which requires further study and linkage to known risk factors and relevant medication exposure.