Online questionnaire, clinical and biomechanical measurements for outcome prediction of plantar heel pain: feasibility for a cohort study

BACKGROUND: Plantar heel pain (PHP) accounts for 11-15% of foot symptoms requiring professional care in adults. Recovery is variable, with no robust prognostic guides for sufferers, clinicians or researchers. Therefore, we aimed to determine the validity, reliability and feasibility of questionnaire, clinical and biomechanical measures selected to generate a prognostic model in a subsequent cohort study. METHODS: Thirty-six people (19 females & 17 males; 20-63 years) were recruited with equal numbers in each of three groups: people with PHP (PwPHP), other foot pain (PwOP) and healthy (H) controls. Eighteen people performed a questionnaire battery twice in a randomised order to determine online and face-to-face agreement. The remaining 18 completed the online questionnaire once, plus clinical measurements including strength and range of motion, mid-foot mobility, palpation and ultrasound assessment of plantar fascia. Nine of the same people underwent biomechanical assessment in the form of a graded loaded challenge augmenting walking with added external weight and amended step length on two occasions. Outcome measures were (1) feasibility of the data collection procedure, measurement time and other feedback; (2) establishing equivalence to usual procedures for the questionnaire battery; known-group validity for clinical and imaging measures; and initial validation and reliability of biomechanical measures. RESULTS: There were no systematic differences between online and face-to-face administration of questionnaires (p-values all > .05) nor an administration order effect (d = - 0.31-0.25). Questionnaire reliability was good or excellent (ICC2,1_absolute)(ICC 0.86-0.99), except for two subscales. Full completion of the survey took 29 ± 14 min. Clinically, PwPHP had significantly less ankle-dorsiflexion and hip internal-rotation compared to healthy controls [mean (±SD) for PwPHP-PwOP-H = 14°(±6)-18°(±8)-28°(±10); 43°(±4)- 45°(±9)-57°(±12) respectively; p < .02 for both]. Plantar fascia thickness was significantly higher in PwPHP (3.6(0.4) mm vs 2.9(0.4) mm, p = .01) than the other groups. The graded loading challenge demonstrated progressively increasing ground reaction forces. CONCLUSION: Online questionnaire administration was valid therefore facilitating large cohort recruitment and being relevant to remote service evaluation and research. The physical and ultrasound examination revealed the expected differences between groups, while the graded loaded challenge progressively increases load and warrants future research. Clinician and researchers can be confident about these methodological approaches and the cohort study, from which useful clinical tools should result, is feasible. LEVEL OF EVIDENCE: IV.