Activation of the gluteus maximus, gluteus medius and tensor fascia lata muscles during hip internal and external rotation exercises at three hip flexion postures

BACKGROUND

Hip internal and external rotation exercises are usually performed in clinical practice. However, given the synergies required to stabilize the hip in the frontal plane, it is not clear how the activation of target muscles will differ between the two exercise directions.

OBJECTIVE

I) Compare the activation of the upper and lower fibers of gluteus maximus (GMax), gluteus medius (GMed) and tensor fascia lata muscles between the hip internal and external rotation exercises; ii) Compare the maximal isometric force between hip internal and external rotation exercises and; iii) Assess the effect of varying hip flexion angles on muscle activation and maximal isometric force.

STUDY DESIGN

A cross sectional study.

METHODS

Electromyography and force production of twenty-one participants were measured during maximum isometric hip internal and external rotation in three postures: 0°, 45° and 90° of hip flexion.

RESULTS

MANOVA results showed a larger activation of the GMed, tensor fascia lata and upper GMax (p < .001) for hip internal rotation compared to external rotation regardless of hip flexion angle. For the lower GMax, the same was observed when the hip was kept at 90° of flexion. Maximal isometric force during hip external rotation was greater than during hip internal rotation at 0° posture, and lower at 90° posture (p < .001).

CONCLUSION

The gluteus and the tensor fascia lata muscles were substantially recruited during the hip internal rotation exercise, and barely recruited during the hip external rotation exercise. Hip flexion influences the myoeletric activity and isometric force production during the internal rotation exercise.

Hip abductor tears in ischiofemoral impingement

PURPOSE

Ischiofemoral impingement (IFI) is associated with abnormalities of the quadratus femoris muscle and narrowing of the ischiofemoral (IF) and quadratus femoris (QF) spaces. The hip abductors play an important role in pelvic stability and abductor tears might play a role in the pathophysiology of IFI. The purpose of our study was to assess the association between hip abductor tears and IFI on MRI.

MATERIALS AND METHODS

The study was IRB approved and HIPAA compliant. Inclusion criteria were MRI findings of IFI (narrowing of the IF space ≤ 15 mm or QF space ≤ 10 mm with associated ipsilateral quadratus femoris edema or fatty infiltration/atrophy). Two MSK radiologists assessed hip/pelvic MRIs and integrity of the tensor fascia lata, gluteus medius, and minimus tendons. IFI and control groups were compared with a two-tailed Student t test or chi-squared test.

RESULTS

We identified 140 patients with MRI findings of IFI (mean age 56 ± 13 years, 130 f, 10 m) and 140 controls of similar age and sex. Patients with IFI had a higher prevalence of gluteus medius/minimus partial tears (37 vs 21, p = 0.02) and full-thickness tears (24 vs 21, p = 0.03). Patients with IFI had a higher prevalence and higher grade of gluteal muscle atrophy compared with controls (p < 0.03). There were no tears of the tensor fascia lata in either group.

CONCLUSION

Patients with IFI had a higher prevalence of abductor tears and abductor muscle atrophy compared with matched controls. This suggests that abductor tears might play a role in the pathophysiology of IFI.

Cadaveric Study on Morphology of Dorsal Interossei of Hand and its Anatomical Variation

INTRODUCTION

The dorsal interossei are the abductors of the fingers and the knowledge of its variation help the surgeon in treatment of fractures, claw hand and compartment syndromes.

AIM

To note the origin, insertion, pattern of muscle fibres and tendon length of all the dorsal interossei of hand.

MATERIALS AND METHODS

Routinely dissected 30 formalin fixed hand in the Department of Anatomy, KMC, Manipal, were observed for origin, insertion and tendon length and muscle pattern of dorsal interossei.

RESULTS

Out of 30 hands, presence of supernumerary muscle was observed in three hands. Presence of three heads of dorsal interossei was noted in one hand.

CONCLUSION

The finding of present study is of importance to surgeons and orthopaedicians during conservative and surgical management of hand deformity. Adequate knowledge of these muscular variations is also important in treatment of fractures, stiff hand, claw hand or tendon transfer.