A clinical prediction rule for identifying patients with patellofemoral pain who are likely to benefit from foot orthoses: A preliminary determination

Abstract

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.