A Prospective Cohort Study on Targeted Exercise and Changes in Femoroacetabular Impingement in Symptomatic Patients With Acetabular Retroversion (TILT-FAI)

Acetabular retroversion is a variation of hip dysplasia, reported in the normal population from 6 % to 48 %, enhancing the risk of femoroacetabular impingement (FAI) in especially hip flexion and is associated with pain, reduced level of function, decreased health-related quality of life and early development of osteoarthritis (OA) of the hip. A higher degree of anterior pelvic tilt increases the risk of FAI and especially in standing, sitting and squatting positions it has been found to correlate with FAI. Periacetabular osteotomy (Ganz osteotomy) is performed as a surgical joint preserving reorientation of the entire acetabulum with a subsequently long period of rehabilitation. There is currently no existing alternative (i.e. non-surgical) treatment to surgery for this patient group. Therefore, the objective of this study is to test a targeted training intervention aiming at reducing anterior pelvic tilt and improve hip joint function in patients with symptomatic acetabular retroversion.

A prospective cohort study of 40 patients will undergo an 8-week targeted exercise intervention executed as progressive home-based training with supervised booster-sessions. Patients (18 to 40 years) with acetabular retroversion and anterior pelvic tilt not eligible for surgery (Ganz osteotomy) will be recruited from the outpatient clinic.

Time points for testing are at 1) minus 8-weeks (beginning of control-period) 2) baseline (beginning of training period) 3) plus 8-weeks (end of training period) and 4) plus 26 weeks from baseline (follow up).

The primary outcome measure is self-perceived level of hip related pain (HAGOS questionnaire subscale). Secondary outcome measures are self-perceived level of function and quality of life (remaining HAGOS-subscales), EQ-5D-3Levels questionnaire and radiographic degree of pelvic tilt in standing posture (EOS-scanning). Explorative outcome measures include additional radiographic measurements, patient-reported outcome measurements (PROM´s), functional testing and physical performance. The primary endpoint for assessing the outcome of the intervention will be 8 weeks after start of intervention. At 26-week follow up, only the PROM´s will be applied. All participants must fill in a mandatory exercise related dairy concerning adherence, level of pain and potential adverse events.

The study is approved by the Regional Committees on Health Research Ethics for Southern Denmark, Project ID: S-20160072 Forty participants in total will be enrolled from the hip outpatient clinic at Odense University Hospital, Denmark. Paired means sample size calculation = 36 (10 % pre-posttest difference on HAGOS pain-subscale, SD=20.6, alpha = 0.05, power = 80 %), plus 10 % dropout = 4.