Clinical Predictors of Foot Orthoses Efficacy in Individuals with Patellofemoral Pain.
Barton CJ, Menz HB, Crossley KM. Med Sci Sports Exerc. 2011;43(9):1603-10.
Foot orthoses are often recommended for patients with patellofemoral pain but previous clinical trials have demonstrated that not every patient reports improvements when prescribed foot orthoses. Several studies have explored variables that might predict which patients will respond to foot orthoses (e.g., less pronated foot type); however, a more thorough evaluation of potential predictive variables is required before we can use this information in clinical practice. Barton et al. evaluated if baseline variables could predict patient-reported improvement in knee symptoms after 12 weeks of wearing foot orthoses among 60 patients with chronic patellofemoral pain. Included patients had no history of foot orthoses in the five years prior to starting the study. All of the potential predictive variables were clinically applicable measurements collected at baseline: patient demographics (e.g., sex, age, height, body mass, weekly physical activity), pain characteristics (e.g., pain duration, number of pain-free step downs), footwear characteristics (e.g., Footwear Assessment Tool; link provides full details), foot and ankle characteristics (e.g., Foot Posture Index [link includes manual], navicular drop, ankle dorsiflexion, first metatarsophalangeal joint dorsiflexion), and immediate changes to function performance (e.g., changes in pain with single leg squat after first getting the orthoses) as well as footwear comfort with foot orthoses (e.g., five-point scale). The prefabricated foot orthoses were commercially-available three-quarter length devices with lateral cutouts made of ethelene-vinyl acetate of medium density, containing built-in arch supports and a four degree varus rear foot wedging (sizes were individualized). After wearing the orthoses for 12 weeks participants were asked to rate their improvements in symptoms using a five-point scale (ranging from markedly worse to markedly better). Only participants reporting markedly better symptoms were considered a successful treatment; all other responses were considered unsuccessful treatments. Fourteen of the 57 participants (25%) that completed the study reported their symptoms were markedly better with the foot orthoses. Limited dorsiflexion, less supportive footwear, low usual pain severity during the week before starting the intervention, and immediate reduction in pain with single leg squats were predictors of marked symptom improvement. The strongest predictor of success was an immediate reduction in pain with single-leg squats when first trying the orthotics at baseline. The greatest accuracy in predicting a successful outcome was produced by positive findings on three of four of these variables (78% success).
This is an interesting study because it tries to evaluate variables that might predict a successful clinical outcome for a certain intervention in a specific patient population. Clinical trials often find that a particular exercise/intervention can improve the average symptoms for a group of patients but what we often forget, even though we see it in clinical practice every day, is that some of those patients have fantastic results, some got a little better, and some don’t get better at all (or maybe get worse). It will be interesting to see the current results tested in future studies that include a control group (so we can determine if these variables predict response to treatment or just predict which patients get better over time). Regardless, this study lays the foundation to address a critical question: can we identify in advance which intervention might be best for a specific patient? This is an area that requires clinicians and researchers talking and working together to identify important variables that might predict successful outcomes. From your experience what predicts a positive clinical outcome with foot orthoses among patients with patellofemoral pain? What seems to predict a positive outcome in general among patients with patellofemoral pain?
Written by: Jeffrey Driban
Reviewed by: Kyle Harris