Lateral foot wedges not effective in medial knee osteoarthritis pain control

Image: PD 

1. Lateral wedges are no more efficacious than neutral wedges at reducing knee pain associated with medial knee osteoarthritis.

2. Lateral wedge insoles show a moderate association with decreased pain when compared to not using an insole. 

Evidence Rating Level: 1 (Excellent) 

Study Rundown: Osteoarthritis of the knee is a painful condition with few effective treatments outside of knee replacement surgery. The most common type of knee osteoarthritis is affects the medial knee. This study focused on the non-surgical treatment of placing a wedge under the lateral sole of the foot to reduce the medial load on the knee. While objective measures of physical stress on the medial knee is known to be decreased with lateral wedges, there has not been clear demonstration on the improvement of pain using lateral wedges.

The goal of this study was to complete the most comprehensive and up-to-date meta-analysis on the efficacy of lateral wedges in reducing pain in the medial knee of osteoarthritis patients. In this analysis, the lateral wedge was shown to decrease pain when compared to using no wedge but did not significantly reduce pain when compared to a neutral wedge. One limitation to this analysis is that only a small number of randomized control trials (RCTs) were included in the final meta-analysis. Furthermore, the meta-analysis is inherently limited by biases within each of the included studies, including the subjective element of quantifying patient pain. Nonetheless, the study represents a persuasive argument that lateral wedges are not indicated for pain control in medial knee osteoarthritis based on the current literature.

Click to read the study, published today in JAMA

Relevant Reading: Physical therapy interventions for knee pain secondary to osteoarthritis: a systematic review

In-Depth [meta-analysis]: The initial literature search found 884 articles. Of these, 872 were eventually discarded, leaving 12 trials that were used for the meta-analysis. Upon compiling all 12 trials, the standardized mean difference (SMD) in pain between interventions was -.47 (95% CI, -0.80 to -0.14), indicating the lateral wedge was able to moderately decrease knee pain levels. However, when the subset of studies using a neutral insole as the control were compared (n=7), lateral wedges did not significantly reduce knee pain (SMD, -0.03; 95%CI, -0.18 to 0.12).

By John Prendergass and Rif Rahman

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