Table I.

Summary of the findings of the articles identified for inclusion (muscle strength in femoroacetabular impingement (FAI))

Authors	Journal (yr)	Title	Level of evidence	Methodology	Key results
Muscle strength in FAI (adults)
Casartelli et al⁷	Osteoarthritis Cartilage 2011	Hip muscle weakness in patients with symptomatic femoroacetabular impingement	2	FAI patients vs controls; 22 participants in each arm; HHD and MDD measures; EMG (rectus femoris and tensor fasciae latae)	FAI patients had signiﬁcantly lower strength than controls for hip adduction (28%), ﬂexion (26%), external rotation (18%) and abduction (11%); EMG activity was signiﬁcantly lower in FAI; Reduced power except internal rotators and extensors.
Diamond et al¹⁰	Br J SportsMed 2015	Physical impairments and activity limitations in people with femoroacetabular impingement: a systematic review	2	Systematic review of physical impairment in FAI (range of movement and strength)	16 studies found, all except Casartelli 2011 paper compared ROM; No new information regarding muscle strength
Harris-Heyes et al¹¹	J Orthop Sports Phys Ther 2014	Persons with chronic hip joint pain exhibit reduced hip muscle strength	3	Young adults with chronic hip joint pain (CHJP) 35 participants and 35 controls; Age 18-40 years; Side lying, HHD used for break tests	All muscle groups weak in affected hip in chronic pain (p < 0.01); ER & abductors weak in unaffected hip of chronic pain participants (p<0.05)