Targeted Exercise and Changes in Femoroacetabular Impingement in Symptomatic Patients With Acetabular Retroversion

The objective of this study is to investigate the effectiveness of an 8-week home-based targeted training intervention aiming at reducing FAI related pain, anterior pelvic tilt and improve hip joint function in a cohort of 40 patients (18 to 40 years), with acetabular retroversion and anterior pelvic tilt not eligible for surgery (Ganz osteotomy) from the hospital outpatient clinic.

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.

A list generated of 20 randomly found numbers from 1-40 will be used to select participants to be investigated in the motion laboratory. The number on the list corresponds to the order the participants are recruited into the study. In the motion laboratory, the explorative outcomes Functional testing (3D motion capture) and Physical performance (isometric muscle strength, joint range-of-motion, and single-leg hop for distance) will be tested.

To our knowledge, this is the first study investigating a targeted training intervention aiming at reducing FAI related pain, anterior pelvic tilt and improve hip joint function in patients with acetabular retroversion. Consequently, the study will provide knowledge that may help to develop non-surgical treatment strategies for this group of patients.

Eligibility Criteria:
Inclusion Criteria:

* Diagnosed from a standard standing anterior-posterior pelvic radiograph with acetabular retroversion due to cross-over-sign and posterior-wall-sign
* Not eligible for Ganz osteotomy
* Ability to take part in the intervention

Exclusion Criteria:

* Having a Pelvic Tilt Ratio greater than 0.5, (the height of the obturator foramen divided by the height of the lesser pelvis) indicating posterior pelvic tilt, assessed from a standard standing AP-pelvic radiograph
* Radiographic sign of hip osteoarthritis (\< 2mm. joint space),
* Previous lumbar, pelvic or hip related operations
* Conditions not allowing exercise therapy
* Body mass index (BMI) above 35
* Not understanding spoken and/or written Danish language