Prevalence of medial tibial stress syndrome in the British Armed Forces: a population-based study.

Introduction: Medial tibial stress syndrome (MTSS) is common in the Armed Forces due to the physical demands placed on service personnel (SP). There are no large studies reporting the extent to which MTSS affects the Armed Forces. A retrospective cross-sectional study design was used to report the annual prevalence of MTSS in the British Armed Forces and in training units and healthcare utilisation.

Methods: Secondary data were sourced from the electronic medical records for all SP with MTSS (20 257) between 1 January 2010 and 31 December 2018. Prevalence was calculated annually across the Armed Forces and in recruits. Healthcare utilisation (number of contacts and days under the care of a healthcare professional) was reported according to characteristics of SP (sex, age, ethnicity, service branch, body composition measurement and medical discharge).

Results: Over 9 years, 20 257 SP were seen for MTSS. Prevalence of MTSS decreased across the Armed Forces, from 2.19% (95% CI 2.12 to 2.26) in 2013 to 1.61% (95% CI 1.55 to 1.68) in 2018. The prevalence of MTSS was 2.7 times higher in recruits, affecting 4.34% (95% CI 4.00 to 4.69) in 2018. In 2018, the prevalence in female recruits was over four times higher (7.03%, 95% CI 5.74 to 8.32) than trained female SP (1.60%, 95% CI 1.39 to 1.81) and higher than male recruits (4%, 95% CI 3.65 to 4.35). Comparing service branches, royal marines had the least healthcare input (median contacts (IQR): 3 (1-7.5)) over the least number of days (median days (IQR): 17 (0-154)), with the royal air force receiving the most (median contacts (IQR): 5 (2-13)) over the greatest number of days (median days (IQR): 76 (4-349)).

Conclusion: The prevalence of MTSS has reduced; however, it remains high in subsections of the Armed Forces, particularly in female recruits. There is a large variation in the amount and duration of healthcare input SP received for MTSS.