The lateral wedge plus medial support orthotic will be custom-made and designed using a 3D volumetric cast of the foot with the participant's foot in a subtalar joint neutral position. The cast will be balanced so that it rests in a neutral position then smoothed to address any irregularities and to allow for soft tissue splay. Polypropylene sheets of 3mm or 4mm thickness will be vacuum formed or milled directly to produce a ¾ length shell. An ethyl-vinyl-acetone (EVA) lateral post in the heel and forefoot of 5 degrees will be incorporated into the orthotic. The orthotic will be finished with a neoprene cover for improved comfort and patient compliance.

The lateral wedge only orthotic will be constructed of EVA, made to full length of the subject's footwear and incorporate a 5 degree posting. The wedge will be finished with a neoprene cover for improved comfort and patient compliance.

This will be a randomized cross-over study where all participants will receive both orthoses over a six month period. Each intervention will last two months, separated by a two month washout period of no orthotics wear, and will be preceded and followed by a laboratory-based gait and pain assessment. Two months has been chosen as the ideal time frame to ensure maximum participant adherence, to observe clinically meaningful changes in symptoms, and to minimize degradation of the insoles.

Participants will undergo three-dimensional gait analysis. This will be performed barefoot with and without the orthotics (conditions tested in a random order). Kinematic and kinetic data will be collected synchronously using high-speed digital cameras and floor-mounted force platforms. Participants will be instructed to walk at a self-selected walking speed measured using photoelectric timing gates and placed along the walkway two metres on either side of the force platforms (note that walking speed during follow-up assessments will be kept similar (+/- 5%) to that chosen by each participant at baseline). A total of five trials will be collected.

The primary loading variable will be the KAM impulse - defined as the area under the KAM curve. Rather than a single peak value, the KAM impulse is more reflective of load experienced over the duration of stance and reflects the cumulative loading experienced at the knee during walking.

The WOMAC is a disease-specific questionnaire that quantifies self-reported joint pain, joint stiffness, and physical function. It is a valid, reliable, and responsive outcome measure that is recommended for use in osteoarthritis clinical trials.

The physical function subscale (17 questions) on the WOMAC will be used.

Participants will rate their perceived foot function and pain using the Foot Function Index (revised - short form). This is a self-report questionnaire which consists of 34 items and provides the ability to quantify aspects of pain, disability and activity limitation. Such assessment of pain has been widely used and is a valid and reliable method in clinical research studies

At follow-up for each orthotic, participants will rate overall perceived change in pain and physical function (vs. baseline) on an ordinal scale (1-much worse, 2-slightly worse, 3-same, 4-slightly better, 5-much better). This will be dichotomized into 'improvement' (4 and 5) or 'no improvement'