Summary of included between-group case–control studies evaluating the effect of FAI and associated pathologies on hip muscle function
| Paper (total score using modified Downs and Black appraisal) | Study characteristics | Sample characteristics | Results | ||||||||
| Inclusion pathology | Outcome measured | Method of measurement | Level of evidence | Sample size | Gender | Age (years) * | (Between-group) Hip group mean (SD) | (Between-group) Control group mean (SD) | Standardised mean difference (SMD) magnitude (95% CI) | Overall main findings | |
| Casartelli et al
27
(10/17) | Unilateral FAI (clinical and radiological diagnosis) | Isometric MVC (hip adduction; abduction; IR; ER; Flex; Ext) Hip flexor EMG activity (RF+TFL) | Isokinetic dynamometry EMG | Case–control | Hips 22 Controls 22 | 8 M/14 W 8 M/14 W | 32 (9) 32 (9) | Adduction 1.57 Nm/kg (0.82); abduction 1.81 Nm/kg (0.43); IR 0.47 Nm/kg (0.16); ER 0.46 Nm/kg (0.21); Flex 0.87 Nm/kg (0.46); Ext 1.64 Nm/kg (1.00); RF 186 (131); TFL 401 (251) | Adduction 2.17 Nm/kg (0.49); abduction 2.03 Nm/kg (0.31); IR 0.55 Nm/kg (0.17); ER 0.56 Nm/kg (0.15); Flex 1.17 Nm/kg (0.37); Ext 1.66 Nm/kg (0.86); RF 294 (184); TFL 582 (323) | Add −0.87 (−1.49 to −0.25), Abd −0.58 (−1.18 to 0.03), IR −0.48 (−1.08 to 0.12), ER −0.54 (−1.14 to 0.06), Flex −0.71 (−1.32 to −0.09), Ext −0.02 (−0.61 to 0.57) RF −0.66 (−1.27 to −0.06), TFL −0.62 (−1.22 to −0.01) | |
| Casartelli et al
26
(Experiment 1) (9/17) | Unilateral FAI (clinical and radiological diagnosis) | Hip flexor Isometric MVC torque Hip flexor EMG activity (RF+TFL) | Isokinetic dynamometry EMG | Case–control | Hips 15 Controls 15 | 6 M/9 W 6 M/9 W | 31 (10) 31 (9) | Isometric MVC torque hip flexors 0.96 (0.46) Nm/kg | Isometric MVC torque hip flexors 1.21 (0.38) Nm/kg | −0.58 (−1.31 to 0.16) | Additional findings to between-group mean: EMG—no group effect and interaction were observed for RMS and MDF of both RF and TFL (p>0.05), whereas a significant effect of time was observed for EMG RMS and MDF of both muscles (p<0.001) |
| Casartelli et al
26
(Experiment 2) (8/17) | Unilateral FAI (clinical and radiological diagnosis) | Hip flexor torque decline (maximal dynamic contractions) | Isokinetic dynamometer | Case–control | Hips 15 Controls 15 | 6 M/9 W 6 M/9 W | 32 (10) 33 (10) | Maximal isokinetic torque hip flexors 0.97 (0.38) | Maximal isokinetic torque hip flexors 1.16 (0.36) | −0.50 (−1.23 to 0.23) | |
| Casartelli et al
23
(8/17) | Unilateral FAI (clinical and radiological diagnosis) | Strength: MVC (hip Abd, Add, IR, ER, Flex and Ext muscle groups) | Handheld dynamometer (Abd, Add, IR and ER) Isokinetic dynamometer (Flex and Ext) | Case series | Hips 8 Controls 8 | 3 M/5 W | 29 (10) | Hip Add 1.64 (0.84); hip Abd 1.93 (0.51); hip IR 0.49 (0.18); hip ER 0.51 (23); hip flexors 1.24 (0.41); hip extensors 1.72 (1.18) | Hip Add 2.39 (0.61); hip Abd 2.23 (0.25); hip IR 0.62 (0.13); hip ER 0.62 (0.14); hip Flex 1.86 (0.31); hip extensors 2.20 (1.13) | Add −0.97 (−2.02 to 0.09), Abd −0.71 (−1.73 to 0.31), IR −0.78 (−1.81 to 0.25), ER −0.55 (−1.55 to 0.46), Flex −1.61 (−2.79 to −0.44), Ext −0.39 (−1.39 to 0.60) | |
| Harris-Hayes et al
30
(10/17) | Chronic hip joint or anterior groin pain >3 months+positive FADIR | Normalised peak muscle torque (hip ER and IR at 90' Flex and N; Abd) | Handheld dynamometer | Case–control | Hips 35 Controls 35 | 7 M/28 W 7 M/28 W | 28 (5) 28 (6) | ERs@90' 3.58 (0.80); IRs@90' 3.57 (1.09); ERs@0' 2.84 (0.80); IRs@0' 2.38 (0.71); Abd 6.98 (2.05) | ERs@90' 4.24 (1.06); IRs@90' 4.96 (1.63); ERs@0' 3.65 (0.89); IRs@0' 3.01 (0.81); Abd 8.95 (1.78) | ER@90 −0.70 (−1.18 to −0.21), IR@90 −0.99 (−1.49 to −0.49), ER@0 −0.95 (−1.44 to −0.45), IR@0 −0.82 (−1.31 to −0.33), Abd −1.01 (−1.51 to −0.52) | |
| Kemp 201419
(14/17) | Chondrolabral pathology at arthroscopy | 12–24 months after arthroscopy—normalised peak torque measured with HHD (Nm/kg) | Handheld dynamometer | Case–control | Hips 84 Controls 60 | 42 M/42 W 19 M/41 W | 36 (10) 36 (10) | Strength Abd men 1.73 (0.45), women 1.16 (0.43); Add men 1.36 (0.35), women 0.99 (0.36); Ext men 1.36 (0.56), women 0.95 (0.49); Flex men 1.19 (0.37), women 0.99 (0.35); ER men 0.82 (0.29); women 0.56 (0.22); IR men 0.61 (0.22); women 0.43 (0.15) | Strength Abd men 1.85 (0.44), women 1.61 (0.35); Add men 1.68 (0.48), women 1.41 (0.36); Ext men 1.62 (0.46), women 1.43 (0.44); Flex men 1.50 (0.34), women 1.44 (0.35); ER men 0.94 (0.32), women 0.72 (0.20); IR men 0.68 (0.22), women 0.55 (0.15) |
Men
s
trength v
ersus
c
ontrols
Abd −0.27 (−0.81 to 0.28), Add −0.80 (−1.36 to −0.24), Ext −0.48 (−1.03 to 0.07), Flex −0.85 (−1.41 to −0.28), ER −0.40 (−0.94 to 0.15), IR −0.31 (−0.86 to 0.23) Women s trength v ersus c ontrols Abd −1.14 (−1.60 to −0.67), Add −1.16 (−1.62 to −0.69), Ext −1.02 (−1.48 to −0.56), Flex −1.27 (−1.75 to −0.80), ER −0.75 (−1.20 to −0.31), IR −0.79 (−1.24 to −0.35) | Additional findings to between-group difference—interaction effect for abduction strength group × sex (p=0.036) |
| Mendis et al
28
(11/17) | Unilateral labral tear awaiting hip arthroscopy (MRI and clinical exam) | 1. Hip Flex torque (Nm). 2. Hip flexor CSA (cm2). | 1. Handheld dynamometer. 2. MRI. | Case–control | Hips 12 Controls 12 | 4 M/8 W 4 M/8 W | 35 (13) 35 (12) | Injured side. Flex strength 37(19). CSA iliacus 9.1 (3.8); psoas 11.5 (4.0); iliopsoas 9.6 (2.0); sartorius 3.1 (0.9); RF 7.1 (2.5); TFL 6.2 (2.5) | Non-injured 47(15). CSA iliacus 9.1 (3.8); psoas 12.0 (3.7); iliopsoas 9.6 (1.8); sartorius 3.0 (0.9); RF 7.4 (2.7); TFL 5.9 (2.2) Controls strength Flex 51 (17); CSA iliacus 9.2 (3.3); psoas 10.9 (3.5); iliopsoas 9.7 (1.7); sartorius 3.0 (0.8); RF 7.9 (2.2); TFL 5.8 (2.2) |
Strength v
ersus
non-injured
Flex −0.56 (−1.38 to 0.26) CSA v ersus non-injured Iliacus 0.00 (−0.80 to 0.80), psoas −0.13 (−0.93 to 0.68), iliopsoas 0.00 (−0.80 to 0.80), sartorius 0.11 (−0.69 to 0.91), RF −0.11 (−0.91 to 0.69), TFL 0.12 (−0.68 to 0.92) Strength v ersus c ontrols Flex −0.75 (−1.58 to 0.08) CSA v ersus c ontrols Iliacus −0.03 (−0.83 to 0.77), psoas 0.15 (−0.65 to 0.96), iliopsoas −0.05 (−0.85 to 0.75), sartorius 0.11 (0.69 to 0.91), RF −0.31 (−1.12 to 0.49) TFL 0.16 (−0.64 to 0.97) Strength non - injured v ersus c ontrols Flex −0.24 (−1.05 to 0.56) CSA non - injured v ersus c ontrols Iliacus −0.03 (−0.83 to 0.77), psoas 0.30 (−0.51 to 1.10), iliopsoas −0.06 (−0.86 to 0.75), sartorius 0.00 (−0.80 to 0.80), RF −0.20 (−1.00 to 0.61), TFL −1.45 (−2.37 to −0.53). | |
No randomised clinical trials were available to include in this review. Significant positive SMDs indicate greater strength in the hip group.
*Mean (SD).
Abd, abduction; Add, adduction; CSA, cross-sectional area; EMG, electromyography; ER, external rotation; Ext, extension; FADIR, flex/adduction/internal rotation; FAI, femoral acetabular impingement; Flex, flexion; HHD, handheld dynamometer; IR, internal rotation; M, male; MDF, median frequency; MVC, maximal voluntary contraction; Nm, Newton metres; RF, rectus femoris; RMS, root mean square; ROM, range of movement; TFL, tensor fascia lata; W, woman.