Reinking MF, Austin TM, Richter RR, Krieger MM. Medial tibial stress syndrome in active individuals: a systematic review and meta-analysis of risk factors. Sport Health. 2017;9:252–261.
Clinical Question: What are the strongest risk factors for medial tibial stress syndrome (MTSS) in active individuals?
Data Sources: Studies were identified by searching PubMed and other databases through May 2012. MTSS was defined as: (1) pain along the posteromedial tibial border, (2) diffuse pain, and (3) pain associated with activity. Keywords from these criteria were combined and used in the search.
Study Selection: Cross-sectional, case–control, and cohort studies were included if they addressed all three criteria of the MTSS definition. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) process was used to identify studies in the final analysis.
Data Extraction: Data extracted from the studies and used in the meta-analysis included: study purpose, study design, setting, participant characteristics, activity associated with MTSS, definition of MTSS, diagnostic tests for MTSS, length of follow-up, risk factors, and risk factor results. Eight indicators were identified a priori and used to assess the quality of studies, including the homogeneity of participants, follow-up length, follow-up greater than 80%, reliability of risk factors, direct measurement of risk factors, diagnosis of MTSS, adjustments, and analysis. Each indicator was scored as “met,” “mixed,” “not met,” “unclear,” or “not reported.” Extracted data were analyzed for statistical heterogeneity using the I2 index and the Cochran Q test. A random-effects model was used to calculate the meta-analysis of pooled summary results for risk factors reported in at least two studies.
Main Results: Of 18,212 potential articles found after an electronic search, 22 studies were selected for meta-analysis following the PRISMA process. Most of the prospective cohort studies (n = 9) “met” the criteria of the quality indicators, whereas most of the cross-sectional (n = 11) and case–control (n = 2) studies were more often scored as “not met” and “not reported” for the criteria. Overall, diagnosis of MTSS and analysis criteria were most often scored as “met” and reliability of risk factors and adjustments were most often scored as “not met.” The 22 included studies reported 27 different risk factors, which were organized into seven categories: demographics/body composition, static posture, gait variables, training variables, injury history, joint mobility, and muscle strength. Greater navicular drop, greater hip external rotation (with hip flexed), female sex, higher weight, and previous running injury were risk factors for MTSS with a significant pooled effect and low heterogeneity. Higher body mass index and greater eversion with running risk factors had a significant pooled effect but moderate-high heterogeneity. A nonsignificant pooled effect was found for all other risk factors (eg, age, height, leg length difference, Q-angle, calf girth, foot angle, tibial varum, years running, weekly mileage, hip and ankle mobility, and ankle strength).
Conclusions: This systematic review and meta-analysis identified five risk factors with a significant pooled effect and low heterogeneity, which were: greater navicular drop, greater hip external rotation (with hip flexed), female sex, higher weight, and previous running injury.
Summary: MTSS is one of the most frequently reported injuries in physically active populations,1–3 but treatment is challenging due to a lack of consensus on etiological factors.4 Without a full etiological understanding, an emphasis on preventive efforts is particularly important and understanding MTSS risk factors is integral in developing preventive measures. Potential MTSS risk factors are body mass index,2,3,5 female sex,1,3 navicular drop,1–3,5 range of motion,1–3 running history/experience,1,3,5 and others. Although individual risk factor studies inform clinical practice, the findings are often based on small sample sizes with conflicting results. Studying the potential risk factors in a systematic fashion can reduce bias and increase confidence through the analysis of pooled data, as done in a meta-analysis.
Collective results from recently published systematic reviews and meta-analyses1–3 provide an opportunity for clinicians to understand MTSS risk factors with greater confidence and then better design specific preventive programs. The most recently published systematic review and meta-analysis is the focus of this article.1 Their findings agree with previously reported systematically reviewed risk factors in regard to navicular drop,2,3 hip external rotation,2,3 and female sex,3 and add higher weight and previous running history as MTSS risk factors.
In the five studies Reinking et al.1 reviewed, the authors reported a navicular drop range of 6 to 7.7 mm for the MTSS group and 3.6 to 5.4 mm for the control group, demonstrating that differences between groups could be as small as 0.6 mm and as large as 4.1 mm. Authors of these five studies measured navicular drop as the difference between navicular height in a weight-bearing position compared to a lesser weight-bearing position (standing vs seated, unilateral stance vs bilateral stance, or stance phase vs heel strike). Using navicular drop as a screening tool may assist clinicians in identifying active individuals at risk for MTSS, but considering the potentially small differences between groups using an instrument with high sensitivity and specificity is important for accurate results. Newman et al.3 found using a dichotomous variable of greater than 10 mm as a measure of increased navicular drop to have a greater effect size than a direct navicular drop measure (the distance the navicular drops between a loaded and lesser loaded position) when comparing MTSS and control groups. Using a dichotomous method of greater than or less than 10 mm would help clinicians confidently assess navicular drop as a strong predictive factor for MTSS.
Similar to navicular drop, Reinking et al.1 reported greater hip external rotation (with hip flexed) as a risk factor for MTSS. Reinking et al.1 included three studies in their meta-analysis, but viewed males and females as separate data sets in two of the three studies, thus giving them five data sets to analyze. Other systematic reviews and meta-analyses included two studies, but reported similar results.2,3 In fact, recent findings suggest for every degree of increased hip external rotation, active individuals are 1.10 times more likely to develop MTSS.5 Interestingly, Newman et al.3 found increased hip external rotation to be a risk factor solely in males. Other authors1,2 did not investigate sex differences in hip external rotation between MTSS and control groups; however, on examination of their forest plots, the mean difference between MTSS and control groups for females is smaller than that of males. Alterations in hip range of motion appear to put males at particular risk for medial tibia injuries,3 which underscores the importance of developing sex-specific preventive programs. The mechanisms behind males with increased hip external range of motion being at risk for MTSS are unclear and in need of further exploration.
Female sex is the remaining MTSS risk factor Reinking et al.1 found in alignment with previous reports.3 Reinking et al.1 reported the odds of having or developing MTSS was 2.35 times greater in females than in males (confidence interval: 1.58 to 3.50), whereas Newman et al.3 reported the incidence of MTSS in females to be 1.71 times that of males (confidence interval: 1.15 to 2.54).6 Various factors may be related to the increased risk of MTSS in females, such as altered kinematics and hormonal or nutritional factors3; prospective studies investigating how these factors implicate MTSS risk are needed.
Despite slightly different methodologies, the three most recent systematic reviews and meta-analyses on MTSS risk factors all found increased navicular drop and greater hip external rotation motion to be risk factors for MTSS.1–3 Reinking et al.1 also reported female sex, higher weight, and previous running injury as likely risk factors, of which Newman et al.3 agreed female sex was a risk factor. A recent prospective cohort study of Navy recruits who developed MTSS over their 11-week basic training program5 concurred with Reinking et al.1 that hip external rotation and female sex put individuals at risk for MTSS and also found individuals with a history of MTSS to be at greater risk for recurring injury, supporting Newman et al.3 When considering Reinking et al.'s1 findings with the collective literature on MTSS risk factors,2,3,5 increased navicular drop, greater hip external rotation (with hip flexed), female sex, and MTSS history are strong risk factors for MTSS.
Knowing the risk factors for MTSS is highly beneficial when working with active individuals, particularly those prone to lower extremity overuse injuries such as runners and military recruits. A simple screening including these key risk factors has the potential to be used to design injury prevention programs and, ideally, decrease injury risk and occurrence. Further prospective research is needed examining intrinsic and extrinsic risk factors for MTSS in active individuals, particularly factors that have not yet been examined such as those proposed by Newman et al.3 and others. More research is also needed on preventive programming and injury risk reduction, but risk factor identification, such as that done by Reinking et al.,1 allows clinicians and researchers to move in that direction.
- Reinking MF, Austin TM, Richter RR, Krieger MM. Medial tibial stress syndrome in active individuals: a systematic review and meta-analysis of risk factors. Sports Health. 2017;9:252–261. doi:10.1177/1941738116673299 [CrossRef]
- Hamstra-Wright KL, Bliven KCH, Bay C. Risk factors for medial tibial stress syndrome in physically active individuals such as runners and military personnel: a systematic review and meta-analysis. Br J Sports Med. 2015;49:362–369. doi:10.1136/bjsports-2014-093462 [CrossRef]
- Newman P, Witchalls J, Waddington G, Adams R. Risk factors associated with medial tibial stress syndrome in runners: a systematic review and meta-analysis. Open Access J Sports Med. 2013;4:229–241. doi:10.2147/OAJSM.S39331 [CrossRef]
- Craig DI. Current developments concerning medial tibial stress syndrome. Phys Sportsmed. 2009;37:39–44. doi:10.3810/psm.2009.12.1740 [CrossRef]
- Garnock C, Witchalls J, Newman P. Predicting individual risk for medial tibial stress syndrome in navy recruits. J Sci Med Sport. 2017;21:586–590. doi:10.1016/j.jsams.2017.10.020 [CrossRef]
- Viera AJ. Odds ratios and risk ratios: what's the difference and why does it matter?South Med J. 2008;101:730–734. doi:10.1097/SMJ.0b013e31817a7ee4 [CrossRef]