Footwear and Exercise for Knee Osteoarthritis (FiREwORK Trial)

Osteoarthritis (OA) is a chronic degenerative joint disease and leading cause of musculoskeletal pain and disability worldwide. The high rates of knee replacement surgery worldwide emphasize the need for more effective non-surgical interventions to attenuate progressive disability. International scientific and professional societies also propose that therapies need to seek efficacious combinations of modalities with the ultimate aim to achieve longer-term, optimal and synergistic treatment effects.

Exercise therapy, such as strengthening and aerobic exercise, is universally, and strongly, recommended as it demonstrates beneficial effects on clinical symptoms and is considered safe for all patients with knee OA. However, during activities as simple as walking, higher knee joint loads have been demonstrated in people with medial tibiofemoral OA, a common form of knee OA. Increased joint loading as such may elicit aggravated symptoms and accelerated joint structural decline over time. No convincing evidence exists to confirm exercise therapy effectively alters joint loading parameters during walking gait in people with knee OA. Notably, recent studies suggest that wearing appropriate footwear may help offload the joint in people with knee OA, a strategy that is also easily applicable at a wide population level.

The purpose of this clinical study is to compare 9-month treatment consisting of exercise therapy and daily wear of one of two shoe classes (flat flexible shoes or stable supportive shoes), on symptom relief and joint structural damage in people with knee OA. In this study, we will randomly allocate eligible participants in one of two treatment arms. This means there will be an equal amount of participants in each group, and participants nor researchers will be able to choose in which group participants will end up in.Participants in both groups will enroll in a 9 month exercise program and will be provided a pair of one of the two shoe classes to wear daily. To ensure an unbiased appraisal of treatment effects, we will not disclose the study hypotheses to participants during the intervention period.

The results of this study will help determine whether the addition of appropriate footwear to exercise therapy improves symptom relief and/or slows structural disease progression in people with knee OA.


Eligibility Criteria:
Inclusion Criteria:

* Symptomatic and radiographic diagnosis of knee OA as per the American College of Rheumatology criteria (ie, aged≥50, knee pain on most days and osteophytes)
* Radiographic evidence of medial OA (ie, Kellgren Lawrence(KL) grade ≥2, ≥grade 1 medial joint space narrowing (JSN) (scale 0-3)\> lateral JSN, using a standardized atlas)
* Average knee pain on walking over the past week of ≥4 on a 11-point numeric rating scale (NRS; "0=no pain" to "10=worst pain imaginable")
* Ability to walk unaided
* Willing to comply with therapy prescriptions
* Sufficient understanding of the Dutch language

Exclusion Criteria:

* Current and previous (3 months) participation in exercise therapy
* Current and previous (3 months) use of customised footwear, minimalist shoes, insoles, braces and unable/unwilling to abandon during the study
* Knee surgery in either knee and/or injections (corticosteroids, hyaluronic acid) in the study knee (most painful knee or right knee if both equally painful) in the past 6 months
* Current or recent (4 weeks) use of oral corticosteroids
* Knee replacement or high tibial osteotomy surgery in the past, or planned during the study
* Inflammatory arthropathies
* Other muscular, joint, neurological or metabolic conditions affecting lower limb function and/or precluding safe regular participation in exercise therapy and walking
* Body mass index (BMI) of \>36 kg/m2 (due to difficulties performing gait analysis and MRI)
* Foot/ankle pain/pathologies at either side, and worse than knee pain complaints
* Contra-indications for radiography \& MRI
* Use of supplements (eg, glucosamine, chondroitin, curcuma derivates) or pain medication (NSAIDs, paracetamol) or other disease modifying or anti-bone resorptive drugs if participants were not on a stable dose for ≥2 months prior to entering the trial