Are Leg Muscle, Tendon and Functional Characteristics Associated with Medial Tibial Stress Syndrome? A Systematic Review

Background: Medial tibial stress syndrome (MTSS) is a common overuse injury that lacks effective evidence-based treatment options. Reduced leg girth has been associated with MTSS development because it is hypothesised to impair the ability of the leg to modulate tibial loading generated during foot–ground contact. Measuring total leg girth, however, does not provide specific information about the structural composition or functional capacity of individual leg muscles. Consequently, uncertainty remains as to which specific muscles are compromised and contribute to MTSS development. Therefore, this paper aimed to systematically review the body of literature pertaining to how the structure and function of the leg muscles are thought to be associated with MTSS injury. Methods: The review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Protocols (PRISMA-P). Medline, PubMed, SCOPUS, SPORTDiscus with Full-texts and Web of Science were searched until March 2021 to identify articles in which lower limb muscle structural or functional variables associated with MTSS injury were investigated. Results: Seventeen studies, which were predominately case–control in design and captured data from 332 individuals with MTSS symptoms and 694 control participants, were deemed appropriate for review. The average Downs and Black Quality Assessment score was 71.7 ± 16.4%, with these articles focussing on leg girth, tendon abnormalities, muscle strength and endurance, shear modulus and neuromuscular control. Of the risk factors assessed in the 17 studies, decreased lean leg girth and higher peak soleus muscle activity during propulsion were most strongly correlated with MTSS development. Individuals with MTSS also displayed deficits in ankle plantar flexor endurance, greater isokinetic concentric eversion strength, increased muscle shear modulus and altered neuromuscular recruitment strategies compared to asymptomatic controls. Conclusions: Future prospective studies are required to confirm whether decreased lean leg girth and higher peak soleus muscle activity during propulsion are associated with MTSS development and to elucidate whether these structural and functional differences in the leg muscles between MTSS symptomatic and asymptomatic controls are a cause or effect of MTSS.