Tensor fascia latae muscle structure and activation in individuals with lower limb musculoskeletal conditions: a systematic review and meta-analysis

In short

Does the tensor fascia latae (TFL) muscle show differences in size or activation in people with lower limb musculoskeletal conditions compared to pain-free individuals?

Current evidence does not consistently support the common clinical assumption that the TFL muscle is structurally or functionally different in people with lower limb musculoskeletal conditions. Findings are contradictory across conditions, methodologies are heterogeneous, and sample sizes are small, preventing firm conclusions.

Mixed pictureRead paper

Meta-analysis17 Trials556 ParticipantsLimited evidence

Key points

17 studies covering 556 participants were included, examining lateral hip pain, hip joint pathology, ACL injury, iliotibial band syndrome, and patellofemoral joint osteoarthritis
Meta-analysis found only a small, low-confidence tendency toward TFL hypertrophy on the affected side in hip joint diseases (SMD 0.37, 95% CI [-0.02, 0.77], p = 0.07)
A moderate effect size was found for a higher TFL/sartorius cross-sectional area ratio in abductor tendon tear (SMD 0.74, 95% CI [0.05, 1.43], p = 0.04)
Normalised EMG amplitude did not differ between groups for any condition; some differences in activation pattern (not amplitude) were observed in lateral hip pain
Timing of TFL activation was delayed in ACL injury with eyes closed (SMD 0.83, 95% CI [0.08, 1.58], p = 0.03) but not different in ITB syndrome

How it was conducted

Design: Systematic review and meta-analysis (PRISMA guidelines, PROSPERO registered CRD42017076160)
Databases: MEDLINE, EMBASE, CINAHL, LILACS from inception to July 2019
Included studies: 17 cross-sectional studies published 2002-2019
Participants: 556 total (299 with musculoskeletal conditions, 257 pain-free controls)
Conditions studied: Lateral hip pain, hip joint pathology, ACL injury, iliotibial band syndrome, patellofemoral joint osteoarthritis
Outcome measures: Muscle structure via MRI (cross-sectional area, volume, fat content) and muscle activation via EMG (amplitude, timing, synergies)

What they found

Meta-analysis of TFL volume on the affected side in hip joint diseases: SMD 0.37, 95% CI [-0.02, 0.77], p = 0.07 (small effect, low confidence)
TFL/sartorius cross-sectional area ratio in abductor tendon tear vs controls: SMD 0.74, 95% CI [0.05, 1.43], p = 0.04 (moderate effect)
Normalised TFL volume in patellofemoral joint OA vs controls: SMD -0.61, 95% CI [-1.23, 0.00], p = 0.05 (moderate effect toward atrophy)
TFL cross-sectional area on affected side in hip joint pathology: SMD -0.53, 95% CI [-0.01, 1.07], p = 0.33 (not significant)
EMG onset time delay (eyes closed) in ACL injury vs controls: SMD 0.83, 95% CI [0.08, 1.58], p = 0.03
Peak TFL EMG during swing phase in lateral hip pain (snapping hip): SMD 2.23, 95% CI [0.95, 3.51], p < 0.01 (proportion of peak activity, not absolute amplitude)
TFL EMG amplitude at 3-minute run in ITB syndrome vs controls: SMD 0.59, 95% CI [-0.19, 1.37], p = 0.14 (not significant)
Mean methodological quality score across all studies: 0.69 (range 0.46-0.91); activation studies scored lower (0.58) than structure studies (0.80)
Inter-rater agreement for quality assessment: kappa 0.847 (almost perfect agreement)

Limitations

All included studies had a cross-sectional design, preventing causal conclusions about whether TFL differences precede or follow the onset of musculoskeletal conditions
Small sample sizes and heterogeneous conditions across studies reduce statistical power and limit condition-specific conclusions
Different EMG normalisation methods across studies preclude direct comparison of activation amplitude between groups
Surface EMG is susceptible to crosstalk from adjacent gluteal muscles, limiting specificity for TFL recordings

Why it matters

For patients: Patients told their TFL is 'overactive' or causing hip and knee problems should know that current research does not consistently support this explanation, and treatment decisions based solely on TFL dysfunction have a weak evidence base.
For clinicians: Clinicians should apply caution when attributing lower limb musculoskeletal conditions specifically to TFL dysfunction, as direct measures of TFL structure and activation do not reliably differ from healthy controls across the conditions studied.
For readers: This systematic review highlights a significant gap between common clinical assumptions about the TFL and the available scientific evidence, underscoring the need for larger, better-designed studies with standardised methods.

Source

doi:10.1007/s40279-019-01251-1

Read the original paper