Table 1

Summary of included cross-sectional studies

Author, year	FAIS group			Controls		Comparability	Task	Reported differences in hip and pelvic kinematics and joint torques: FAIS compared with controls
Author, year	FAIS type	Inclusion criteria	Sample	Criteria	Sample	Comparability	Task
Bagwell et al, 201630	Unilateral Cam only FAIS	≤45 years older Skeletally mature Unilateral hip pain with no OA α>50.5° (axial oblique MRI)	n=15 6 men Age 31.9 (7.6)	Negative log roll <5 cm asymmetry FABER Nil pain passive hip internal rotation No hip or back pain No lower limb/back surgery α<50.5° (axial oblique MRI) CEA between 20° and 40°	n=15 6 men Age 32.7 (7.8)	Age Sex Mass	Squat	FAIS group squatted to a lesser depth with: Less mean hip flexor torque Greater anterior pelvic tilt at peak hip flexion and smaller peak femur flexion Smaller peak hip internal rotation angle
Diamond et al, 201625	Cam or combined FAIS	Positive impingement tests 3 months of hip/groin pain No history of hip surgery Kellgren-Lawrence grade <3 α>55° (oblique sagittal plane, MRI) AND/OR CEA>39° (coronal plane MRI)	n=15 11 men Age 24.7 (4.9)	No history of hip or groin pain No previous hip surgery No morphological FAIS α<50°* (oblique sagittal plane MRI) CEA<40°* (coronal plane MRI)	n=14 10 men Age 27.1 (4.5)	Age Sex BMI Dominant leg	Walking	FAIS group walked with: Less total sagittal plane ROM in cycle
Hammond et al, 201733	Cam, pincer or combined FAIS	<40 years old Preoperative FAIS No previous lower limb surgery or radiographic OA Radiographic confirmation (angles/view NR)	n=20 15 men Age 27.6 (5.8)	No hip or back pain (self-reported) No history of lower body injuries No history of hip OA	n=20 15 men Age 27.1 (5.0)	Age Sex Height BMI	Stairs	FAIS group completed stairs: With greater peak hip flexion moment
Hetsroni et al, 201526	Cam or combined FAIS	Men aged 18 years or older Insidious onset of hip pain Positive impingement sign and relieved after intra-articular injection Absence of lower limb injuries α>60° (view NR MRI) CEA between 25° and 40° (view NR, MRI)	n=15 15 men Age 33 (6)	Men only aged 18 years or older Absent lower limb abnormalities on assessment Negative hip impingement test No lower limb injuries	n=15 (30 hips) 15 men Age 28 (6)	Sex BMI	Walking	FAIS group walked with: Greater sagittal plane pelvic ROM Smaller pelvic internal rotation angle at heel strike Smaller hip abduction angle at heel strike
Hunt et al, 201327	Cam, pincer or combined FAIS	Anterior groin pain Presentation consistent with FAIS Positive impingement sign No history of hip surgery No signs of OA MR arthrogram confirmation (angles/view NR)	n=30 25 men Age 28.4 (6.9)	No lower limb extremity pain or dysfunction No previous hip surgery Negative impingement signs	n=30 20 men Age 27.5 (5)	Age Sex	Walking	FAIS group walked with: Smaller peak hip extension angle Smaller peak hip adduction angle Smaller peak hip internal rotation Smaller peak hip flexion and external rotation joint torque
Kennedy et al, 200924	Unilateral cam only FAIS	Positive impingement test No hip OA on X-ray α>50.5° (AP and Dunne X-ray)	n=17 10 men Age 35.5 (10.6)	No history of serious lower limb injury or surgery No hip pain or stiffness No functional problems according to the WOMAC No hip OA on X-ray α NR (AP X-ray)	n=14 8 men Age 34.2 (9.5)	Age Sex BMI	Walking	FAIS group walked with: Less total sagittal plane hip ROM Less total frontal plane hip and pelvic ROM Smaller peak hip abduction angle
Kumar et al, 201428	Unilateral cam only	Positive impingement test No neurological disorders Able to undergo MRI α>55° (oblique axial MRI, AP and frog leg X-ray)	n=7 5 men Age 36.6 (9.7)	No lower limb pain A history of no lower limb surgery or serious injury No neurological disorders Able to undergo MRI α and CEA NR (view NR, MRI)	n=8 8 men Age 27.3 (7.7)	Age Sex BMI	Walking Squat Drop landing	FAIS group squatted with: Greater peak hip adduction angle Greater peak hip external rotation torque
Lamontagne et al, 200931	Unilateral cam only FAIS	Positive impingement test No OA or joint space narrowing on X-rays α>50.5° (AP and Dunne X-ray)	n=15 9 men Age 35.3 (9.1)	No history of lower limb injury No lower limb surgery No OA or joint space narrowing on radiographs α NR (AP X-ray)	n=11 6 men Age 34.5 (10.1)	Age Sex BMI	Squat	FAIS group squatted with Less total sagittal pelvic ROM
Ng et al, 201532	Cam only FAIS	Positive impingement test Plan to undergo orthopaedic surgery Hip pain No neurological/musculoskeletal injury BMI<30 kg/m² Radial α>60° (oblique axial CT) OR Axial α>50.5° (oblique axial CT)	n=12 12 men Age 38 (9)	No clinical signs or symptoms No neurological or musculoskeletal or major lower limb injury/disorder BMI<30 kg/m² Radial α<60° (oblique axial CT) Axial α<50.5° (oblique axial CT)	n=14 14 men Age 32 (6)	Age Sex BMI	Squat	No reported differences
Samaan et al, 201734	Cam, pincer or combined FAIS	Positive FADIR test No joint replacements No previous lower limb surgery on test limb No hip OA BMI<35 kg/m² α>55° (oblique axial MRI and AP X-ray) OR CEA>35° (oblique axial MRI and AP X-ray)	n=17 13 men Age 40.1 (7.2)	No joint replacements No previous lower limb surgery on test limb No hip OA BMI<35 kg/m² α NR (oblique axial MRI and AP X-ray) CEA NR (oblique axial MRI and AP X-ray)	n=31 17 men Age 41.4 (12.6)	Age Sex BMI	Sit-to-stand	No reported differences
Samaan et al 201729	Cam, pincer or combined FAIS	Positive FADIR test No joint replacements No previous lower limb surgery on test limb No hip OA α>55° (oblique axial MRI and AP X-ray) OR CEA>35° (oblique axial MRI and AP X-ray)	n=15 11 men Age 40.1 (7.5)	No joint replacements No lower limb pain No hip OA Negative FADIR test Previous hip trauma α NR (oblique axial MRI and AP X-ray) CEA NR (oblique axial MRI and AP X-ray)	n=34 19 men Age 43.2 (12.4)	Age Sex BMI	Walking	FAIS group walked with: Larger hip flexion torque impulse

Age reported as means (SD); all joint torques listed as external.
*Control inclusion reported as alpha angles >50° and centre edge angles >40°. This was considered an error.
AP, anterior-posterior; BMI, body mass index; CEA, centre edge angle; FABER, flexion abduction and internal rotation; FADIR, flexion adduction and internal rotation; FAIS, femoroacetabular impingement syndrome; NR, not reported; OA osteoarthritis; ROM, range of motion; WOMAC, Western Ontario and McMaster Universities Osteoarthritis Index; α, alpha angle.