THE IMPORTANCE OF HIP ABDUCTORS’ ENDURANCE IN DYNAMIC KNEE VALGUS AFTER ISOKINETIC FATIGUE

E. Lagouvardou^1,2, K. Vassis^1,2, M. Ntoulias², A. Kanellopoulos^1,2, I. Poulis^1,2

¹School of Health Sciences, University of Thessaly, Faculty of Physiotherapy, Lamia, Greece, ²Human Performance and Rehabilitation Laboratory, Faculty of Physiotherapy, Lamia, Greece

Background: Anterior Cruciate Ligament (ACL) is a multifactorial phenomenon that occurs in jumps, landing and cutting movements with a greater frequency of appearance in females. Dynamic Knee Valgus (DKV), is present in 70-80 % of ACL injuries. Several studies report that the strength of hip abductors is an essential reason for the presence of DKV. Neuromuscular fatigue is a phenomenon that is not absent in high-intensity and demanding sports. However, limited studies have examined abductor fatigue and its effects on knee movement in the frontal plane.

Purpose: To investigate the variation of DKV after isokinetic fatigue of the hip abductors in physically active women during the Single Leg Squat (SLS) and Single Leg Landing (SLL) functional tests. Also,
1) the correlation between hip abductors' strength and DKV and
2) the correlation between hip abductors' strength after fatigue with DKV.

Methods: 23 physically active women, aged 18 to 28 years, participated in the study. Hip abductors' Mean Peak Moment (MPM) evaluation and fatigue processes were achieved isokinetically at a speed of 120°/sec. The assessment of DKV was performed at the maximum tibiofemoral angle of the frontal plane through the functional tests using the Kinovea application.

Results: DKV decreases after the fatigue protocol with statistically significant results during the SLL (p=0.035). No correlation was found between abductors' MPM and DKV in both functional tests. A mild negative correlation was observed (r=-0.476, p=0.022), between abductors' MPM after the fatigue protocol and DKV, during the SLL.

Conclusions: DKV seems to decrease after the fatigue protocol in the SLL. Fatigue probably causes compensatory adjustments and changes in the movement patterns of other joints. No correlation was found between abductors' MPM and DKV, however a mild negative correlation was observed between abductors' MPM after fatigue protocol and DKV during the SLL. This indicates that DKV is more affected by abductors' endurance than abductors' strength. Future studies should examine if hip abductor endurance must be an integral part of contemporary injury prevention programs.

Implications: Evaluating DKV during functional tests such as SLL, in combination with abductors' endurance may be a better screening tool for knee injuries. Hip abductor endurance may be more important than abductor strength in reducing dynamic knee valgus and consequently, knee injuries. Knee injuries are a multifactorial phenomenon and in order to prevent possible ACL injuries, we need to investigate more factors simultaneously.

Funding acknowledgements: This research received no external funding.

Keywords:
Fatigue
Hip abductors
Dynamic knee valgus

Topics:
Musculoskeletal: lower limb
Musculoskeletal
Sport & sports injuries

Did this work require ethics approval? Yes

Institution: School of Health Sciences, University of Thessaly

Committee: Research Ethics Committee of Department of Physiotherapy

Ethics number: 644-09/09/21