Skip to main content

Research Repository

Advanced Search

Squatting biomechanics following physiotherapist-led care or hip arthroscopy for femoroacetabular impingement syndrome: a secondary analysis from a randomised controlled trial

Grant, Tamara M.; Saxby, David J.; Pizzolato, Claudio; Savage, Trevor; Bennell, Kim; Dickenson, Edward; Eyles, Jillian; Foster, Nadine; Hall, Michelle; Hunter, David; Lloyd, David; Molnar, Rob; Murphy, Nicholas; O’Donnell, John; Singh, Parminder; Spiers, Libby; Tran, Phong; Diamond, Laura E.


Tamara M. Grant

David J. Saxby

Claudio Pizzolato

Trevor Savage

Kim Bennell

Edward Dickenson

Jillian Eyles

Nadine Foster

Michelle Hall

David Hunter

David Lloyd

Rob Molnar

Nicholas Murphy

John O’Donnell

Parminder Singh

Libby Spiers

Phong Tran

Laura E. Diamond


Femoroacetabular impingement syndrome (FAIS) can cause hip pain and chondrolabral damage that may be managed non-operatively or surgically. Squatting motions require large degrees of hip flexion and underpin many daily and sporting tasks but may cause hip impingement and provoke pain. Differential effects of physiotherapist-led care and arthroscopy on biomechanics during squatting have not been examined previously. This study explored differences in 12-month changes in kinematics and moments during squatting between patients with FAIS treated with a physiotherapist-led intervention (Personalised Hip Therapy, PHT) and arthroscopy.

A subsample (n = 36) of participants with FAIS enrolled in a multi-centre, pragmatic, two-arm superiority randomised controlled trial underwent three-dimensional motion analysis during squatting at baseline and 12-months following random allocation to PHT (n = 17) or arthroscopy (n = 19). Changes in time-series and peak trunk, pelvis, and hip biomechanics, and squat velocity and maximum depth were explored between treatment groups.

No significant differences in 12-month changes were detected between PHT and arthroscopy groups. Compared to baseline, the arthroscopy group squatted slower at follow-up (descent: mean difference −0.04 m∙s−1 (95%CI [−0.09 to 0.01]); ascent: −0.05 m∙s−1 [−0.11 to 0.01]%). No differences in squat depth were detected between or within groups. After adjusting for speed, trunk flexion was greater in both treatment groups at follow-up compared to baseline (descent: PHT 7.50° [−14.02 to −0.98]%; ascent: PHT 7.29° [−14.69 to 0.12]%, arthroscopy 16.32° [−32.95 to 0.30]%). Compared to baseline, both treatment groups exhibited reduced anterior pelvic tilt (descent: PHT 8.30° [0.21–16.39]%, arthroscopy −10.95° [−5.54 to 16.34]%; ascent: PHT −7.98° [−0.38 to 16.35]%, arthroscopy −10.82° [3.82–17.81]%), hip flexion (descent: PHT −11.86° [1.67–22.05]%, arthroscopy −16.78° [8.55–22.01]%; ascent: PHT −12.86° [1.30–24.42]%, arthroscopy −16.53° [6.72–26.35]%), and knee flexion (descent: PHT −6.62° [0.56– 12.67]%; ascent: PHT −8.24° [2.38–14.10]%, arthroscopy −8.00° [−0.02 to 16.03]%). Compared to baseline, the PHT group exhibited more plantarflexion during squat ascent at follow-up (−3.58° [−0.12 to 7.29]%). Compared to baseline, both groups exhibited lower external hip flexion moments at follow-up (descent: PHT −0.55 N∙m/BW∙HT[%] [0.05–1.05]%, arthroscopy −0.84 N∙m/BW∙HT[%] [0.06–1.61]%; ascent: PHT −0.464 N∙m/BW∙HT[%] [−0.002 to 0.93]%, arthroscopy −0.90 N∙m/BW∙HT[%] [0.13–1.67]%).

Exploratory data suggest at 12-months follow-up, neither PHT or hip arthroscopy are superior at eliciting changes in trunk, pelvis, or lower-limb biomechanics. Both treatments may induce changes in kinematics and moments, however the implications of these changes are unknown.

Trial registration details
Australia New Zealand Clinical Trials Registry reference: ACTRN12615001177549. Trial registered 2/11/2015.


Grant, T. M., Saxby, D. J., Pizzolato, C., Savage, T., Bennell, K., Dickenson, E., …Diamond, L. E. (in press). Squatting biomechanics following physiotherapist-led care or hip arthroscopy for femoroacetabular impingement syndrome: a secondary analysis from a randomised controlled trial. PeerJ, 12, Article e17567.

Journal Article Type Article
Acceptance Date May 23, 2024
Online Publication Date Jun 24, 2024
Deposit Date Jul 9, 2024
Journal PeerJ
Publisher PeerJ
Peer Reviewed Peer Reviewed
Volume 12
Article Number e17567
Keywords Kinematics, Kinetics, Squat, Hip joint, Physical therapy
Public URL
Publisher URL