Objective To develop a clinical prediction rule to identify patients with patellofemoral pain (PFP) who are more likely to benefit from foot orthoses.
Design Posthoc 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 cm), worst pain visual analogue scale (<53.25 mm) and a difference in mid-foot width from non-weight bearing to weight bearing (>10.96 mm). The pretest success rate of 40% increased to 86% if the patient exhibited three of these variables (positive likelihood ratio 8.8; 95% CI 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.
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Funding The RCT was funded primarily by the National Health and Medical Research Council of Australia (Primary Health Care Project Grant #301037). NC was the recipient of a National Health and Medical Research Council of Australia Public Health Scholarship (#351663). Vasyli International donated the foot orthoses. The funding organisations had no involvement in the study design, data collection, analysis and interpretation, writing of the report, or decision to submit the paper for publication.
Competing interests BV has been reimbursed by Vasyli International for seminar presentations not directly related to this study and has also received research funding from this company. Vasyli International is the manufacturer and donator of the foot orthoses in this study. All other authors declare that they have no competing interests.
Ethics approval Ethics approval was conferred by the University of Queensland's Medical Research Ethics Committee.
Patient consent Obtained.
Provenance and peer review Not commissioned; externally peer reviewed.