First-line Treatment for Femoroacetabular Impingement Syndrome

There is sparse evidence on the effectiveness of first-line treatment in patients with femoroacetabular impingement syndrome (FAIS) regarding clinical- and cost-effectiveness. The goal of this randomized controlled trial is to compare the clinical effectiveness and cost-effectiveness of a supervised strength exercise intervention to usual first-line care in patients with FAIS. The main hypothesis it aims to investigate are: 1. 6-months of supervised strength exercise intervention is superior (i.e., at least 6 points, on a scale from 0-100) to usual care in improving hip related quality of life in patients with FAIS at the end of intervention. 2. 6-months of supervised strength exercise intervention is cost-effective compared to usual first-line care at 12-month follow-up in patients with FAIS. 3. High exercise adherence and dosage will be superior to low exercise adherence and dosage in mediating clinical effectiveness in patients with FAIS.

Inclusion Criteria: 1. Activity- or position-related pain lasting ≥ 3 months 2. Positive Flexion-Adduction-Internal rotation (FADIR) test 3. Cam-type FAIS; x-ray alpha angle =\> 60 degrees 4. Pincer-type FAIS; lateral center edge angle \> 39 degrees or crossover-sign 5. Mixed-type FAIS; a combination of cam- and pincer-type impingement 6. Motivated to exercise 2 times a week for 6 months 7. 18-50 years old 8. Body Mass Index (BMI) score \< 35 Exclusion Criteria: 1. Physiotherapist-led strengthening exercises targeting the hip for at least 3 months for ≥ 6 sessions prior to inclusion 2. Previous hip surgery or other major hip injury in index hip (i.e., hip arthroscopy, fracture, calves perthes, necrosis or luxation). 3. Evidence of pre-existing osteoarthritis, defined as Tönnis grade ≥ 2 or Kellgreen-Lawrence ≥ 2 4. Evidence of pre-existing osteoarthritis, defined as lateral joint space width ≥ 3 mm (measured at the lateral sourcil). 5. Hip dysplasia, defined as a Center-Edge-angle (CE-angle) ≤ 25° and an acetabular index \> 10° 6. Comorbidities or other problems considered to affect hip function and participation in exercise 7. Unable to communicate in the respective languages of the participating countries