Objective: To develop a clinical prediction rule to identify patients with patellofemoral pain (PFP) who are more likely to benefit from foot orthoses.
Design: Post-hoc analysis of one treatment arm of a randomised clinical trial.
Setting: Single centre trial in a community setting in Brisbane, Australia.
Participants: 42 participants (mean age 27.9 years) with a clinical diagnosis of PFP (median duration 36 months).
Interventions: Foot orthoses fitted by a physiotherapist.
Main outcome measures: Five-point global improvement scale at 12-week follow-up, dichotomised with marked improvement equalling success.
Results: Potential predictor variables identified by univariate analyses were age, height, pain severity, Anterior Knee Pain Scale score, Functional Index Questionnaire score, foot morphometry (arch height ratio, mid foot width difference from non-weight bearing to weight bearing), and overall orthoses comfort. Parsimonious fitting of these variables to a model that explained success with orthoses identified the following: age (> 25 years), height (< 165 centimetres), worst pain visual analogue scale (< 53.25 millimetres) and a difference in mid-foot width from non-weight bearing to weight bearing (> 10.96 millimetres). The pre-test success rate of 40% increased to 86% if the patient exhibited three of these variables (positive likelihood ratio 8.8 (95% confidence interval 1.2 to 66.9)).
Conclusion: Post-hoc analysis identified age, height, pain severity and mid foot morphometry as possible predictors of successful treatment of PFP with foot orthoses, thereby providing practitioners with information for prescribing foot orthoses in PFP and stimulating further research. Trial registration Australian Clinical Trials Registry ACTRN012605000463673 ClinicalTrials.gov NCT00118521