Foot posture as a risk factor for lower limb overuse injury: a systematic review and meta-analysis

Background Static measures of foot posture are regularly used as part of a clinical examination to determine the need for foot level interventions. This is based on the premise that pronated and supinated foot postures may be risk factors for or associated with lower limb injury. This systematic review and meta-analysis investigates foot posture (measured statically) as a potential risk factor for lower limb overuse injuries. Methods A systematic search was performed using Medline, CINAHL, Embase, SportDiscus in April 2014, to identify prospective cohort studies that investigated foot posture and function as a risk factor for lower limb overuse injury. Eligible studies were classified based on the method of foot assessment: (i) static foot posture assessment; and/or (ii) dynamic foot function assessment. This review presents studies evaluating static foot posture. The methodological quality of included studies was evaluated by two independent reviewers, using an adapted version of the Epidemiological Appraisal Instrument (EAI). Where possible, effects were expressed as standardised mean differences (SMD) for continuous scaled data, and risk ratios (RR) for nominal scaled data. Meta-analysis was performed where injuries and outcomes were considered homogenous. Results Twenty-one studies were included (total n = 6,228; EAI 0.8 to 1.7 out of 2.0). There was strong evidence that a pronated foot posture was a risk factor for medial tibial stress syndrome (MTSS) development and very limited evidence that a pronated foot posture was a risk factor for patellofemoral pain development, although associated effect sizes were small (0.28 to 0.33). No relationship was identified between a pronated foot posture and any other evaluated pathology (i.e. foot/ankle injury, bone stress reactions and non-specific lower limb overuse injury). Conclusion This systematic review identified strong and very limited evidence of small effect that a pronated foot posture is a risk factor for MTSS and patellofemoral pain respectively. Evaluation of static foot posture should be included in a multifactorial assessment for both MTSS and patellofemoral pain, although only as a part of the potential injury risk profile. Whilst the included measures are clinically applicable, further studies are required to determine their relationship with dynamic foot function. Electronic supplementary material The online version of this article (doi:10.1186/s13047-014-0055-4) contains supplementary material, which is available to authorized users.


Is the hypothesis or aim or objective of the study clearly described?
The objective is clearly stated in one or two statements in the introduction (Might include but not limited tostudy design -prospective cohort/study/design, adequate discription of-how foot posture is investigated and injury/s of interest so that the study can be replicated) There is sufficient information to be able to infer the objective in the introduction The study objective is not described in the introduction and there is insufficient information provided to even 'infer' Exposure 2. Are all the risk factor variable(s) related to foot posture clearly described?
The definitions of all risk factor variables related to foot posture are referenced to a clear description (e.g. Navicular Drop + description) if described with reference Yes (pending) The definitions of all risk factor variable related to foot posture are not clearly described, but sufficient information is provided for the reader to understand the intent (e.g. Navicular drop with poor description) OR Some, but not all, of the foot posture relatd risk factor variables are described (i.e. multiple foot posture risk factors are investigated, but only individual risk factors are described) No mention of definition of risk factor variables related to foot posture (e.g. Navicular drop without description) "All risk factor variables" may only include a single foot risk variable i.e. individual measure of foot posture Non-foot posture related risk factor variables do not need to be analysed in this question Outcome

Is injury clearly described?
The definition of all injuries are referenced to a clear description (e.g. Injury + adequate discription of how injury will be determined and measured) The definition of all injuries are not clearly described, but sufficient information is provided for the reader to understand the intent (i.e. Injury with poor description of how injury will be determined and measured) No mention of definition of injury (e.g. Injury without description of how injury will be determined or measured) Study Design 4. Is the study design clearly described? The study design is clearly described using the following terminology (or similar): prospective cohort Study design has to be inferred (i.e. prospective study, no use of the word cohort or group was followed over time etc.) No mention of study design (i.e. no description) 5. Is the source of subject population (including sampling frame) clearly described?
The following details are clearly described: 1. Geographic location and/or setting-Australia, Uk or setting 2. Type of list of potential subjectswhere were subjects recruited from e.g. military personal, running club 3. Time frame of initial participant data collection-eg participants were collected over x weeks (needs to be a specific measure of time) One or more of the following details reported: 1. Geographic location and/or setting-Australia, Uk or setting 2. Type of list of potential subjectswhere were subjects recruited from e.g. military personal, running club 3. Time frame of initial participant data collection-eg participants were collected over x weeks (needs to be a specific measure of time) No mention of source population 6. Are the eligibility criteria for subject selection clearly described?
Inclusion and/or exclusion criteria of the study population are clearly described in a few sentences Characteristics of subjects lost or details are described in an equally detailed way to question 8 -"Yes" OR There are no losses or losses are so small that findings would be unaffected (less than 10% for each group or 10% of overall population) The characteristics are poorly described in an equally detailed way to question 8 -"Partial" OR Losses in all groups are less than 20% Characteristics of subjects lost/unavailable records are not reported OR Losses in all groups are greater than 20% Subjects lost = participants dropped out after initial data was collected

Have all important adverse effects been reported that may be consequences of the interventions?
Cohort study (no intervention)

Are the important intrinsic risk factors (confounders and covariates) for injury been described in terms of individual variables?
All intrinsic risk factors (all from the green list below) have been listed and described Some (but not all) intrinsic risk factors (one or more from the green list below) have been listed and described No mention of any co-variates or confounders

Are the important extrinsic risk factors (confounders and covariates) for injury been described in terms of individual variables?
All extrinsic risk factors (all from the red list below) have been listed and described Some (but not all) extrinsic risk factors (one or more from the red list below) have been listed and described No mention of any co-variates or confounders

Study Population
Statistical Tests 13. Are the statistical methods clearly described?
All relevant statistical tests are listed and clearly described (i.e. Chi squared, multiple logistic analysis etc.) AND All confounders and co-variates (all from red and green the list below) did not statistically affect the injury rate Some but not all relevant statistical tests are listed and clearly described (eg Chi squared, multiple logistic analysis etc.) AND Some but not all confounders and covariates that were investigated in the study (1 or more from the red and green list below) did not statistically affect the injury rate No mention of any statistical test OR No confonfounders investigated were reported OR Any other situation not listed under "Yes" or "Partial"

Are the main findings of the study clearly described?
Basic data for all foot posture related risk factor variables and all injury outcome are reported so that the reader can check the major analyses and conclusions Basic data for foot posture related risk factor variables and injury outcome are reported for some (but not all) groups No mention of any outcome or risk factor data OR Any other situation not listed under 'Yes' or 'Partial' "All risk factor variables" may only include a single foot risk variable ie. individual measure of foot posture Non-foot posture related risk factor variables do not need to be analysed in this question. 15. Does the study provide estimates of the random variability in the data for the outcome of interest (i.e. confidence intervals, standard deviations)?
For normal data, confidence intervals or standard errors for all outcomes (injury) or foot posture related risk factors OR The inner quartile range for nonnormally distributed data for all outcomes (injury) or foot posture related risk factors Estimates of random variability (ie. Confidence intervals etc) are reported for some (but not all) outcomes (injury) and foot posture related risk factor variables Only provides results for overall population No mention of any estimates of random variability OR any other situation not described under 'Yes' or 'Partial'

Does the study provide estimates of statistical parameters (eg. Regression coefficients or parameter estimates such as odds ratio)? Ie magnitude of significance
Estimates are reported for all different parameters (injury or foot posture risk factor variables) i.e. Odds/risk ratio or effect size for the development of injury for all foot posture risk factors investigated Estimates are reported for some (but not all) groups (designs specifying groups) OR Estimates are only provided for some parameters OR Only provides results for overall population No mention of any estimates OR Any other situation not listed under 'Yes' or 'Partial' "All risk factor variables" may only include a single foot risk variable ie. individual measure of foot posture Non-foot posture related risk factor variables do not need to be analysed in this question

Are sample size calculations performed and reported?
The study has performed an analysis where calculations were used and reported in the paper to determine how many participants were required for the calculation of all of the following: -effect size -type I or II errors -number of confounders Characteristics of non-responders or unavailable records are described in identical way (Question 9 -"Yes") and are not significantly different from those of the study participants or available records OR Losses <10% Characteritics of non-responders or unavailable records are described in identical way to those of the participating subjects or available records (Question 9 -"Yes") BUT no mention of statistical differences among groups OR Losses <20% No mention or poor discription of nonresponder characteristics and/or unavailable records (Question 9 -"Partial" or "No") OR Any other situation not listed under 'Yes' or 'Partial' N/A for national survey OR convenience samples where 100% participation rate is reported or inferred Losses refer to subjects that were lost after initial data was collected Type of Cases

Are newly incident cases taken into account?
Cohort observational study (no intervention)

Are the study subjects randomised to groups?
Cohort observational study (no intervention)

Is the randomised assignment to groups concealed from both subjects and observers until recruitment is complete irrevocable?
Cohort observational study (no intervention)

Are measurement methods for risk factor variables reliable?
Reliability > 0.70 for all foot posture risk factor variables AND Study needs to use the word "reliability" (or similar) followed by the reference or determined value -Determined there own reliability -Reference of reliability (Yespending) Reliability ≥0.40 for all foot posture risk factor variables AND Study needs to use the word "reliability" (or similar) followed by the reference or determined value -Determined there own reliability -Reference of reliability (Partialpending) Reliability <0.40 for at least one foot posture risk factor variable OR Poor documentation of reliability from prior work from the published literature -study uses the word "reliability" (or similar) but does not present determined value or reference Subjects are truly blinded to exposure/intervention and comparison groups (i.e. by design, the subjects are blinded to their group AND there is no way that the subjects are aware of their grouping) Subjects are not truly blinded (i.e. by design, the subjects are blinded to their group; however , you may infer that it is possible for the subjects to figure out which group they are in) Subjects are not blinded Cross-sectional design utilising only overall population without specific groups A score of N/A would be considered for studies that have grouped participants after injury is recorded not at baseline

Insuffiecient details
For single group cohort studies, choose N/A.

A score of N/A would be considered for studies that have grouped participants after injury is recorded not at baseline
For cohort studies that split groups at baseline based on risk factors (e.g. Supinated vs. Pronated), choose criteria based on whether the observers knew which group subjects were allocated to at baseline (i.e. prior to reporting injury)

Is reliability described for the measurement of the injury of interest?
Reliability > 0.70 for outcome (injury) variables And Study needs to use the word "reliability" (or similar) followed by the reference or determined value -Determined there own reliability -Reference of reliability (Yespending) Reliability ≥0.40 for outcome (injury) variables And Study needs to use the word "reliability" (or similar)followed by the reference or determined value -Determined there own reliability -Reference of reliability (Partialpending) Reliability <0.40 for outcome (injury) variables OR Poor documentation of reliability from prior work from the published literature -study uses the word "reliability" (or similar) but does not present determined value or refernce No mention of reliability of outcome variables

Is validity described for the measurement of the injury of interest?
VALID: Outcome measure is the gold standard OR Validity > 0.70 if outcome measure is not the gold standard OR Detailed documentation of validity from prior work from the published literature -study needs to use the word "validity" (or similar) followed by a reference or determined value The results are expected to apply to other relevant groups; study sample is taken by random sampling from the general population (eg electoral role) The results are somewhat applicable to other relevant groups; study sample taken by convenience sampling Results are not applicable to other relevant groups; biased sample of individuals seeking treatment for foot problems OR cases are studied with no control group Sampling method not reported