Individuals with sacroiliac joint dysfunction display asymmetrical gait and a depressed synergy between muscles providing sacroiliac joint force closure when walking

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Abstract

Walking is often compromised in individuals with low back and hip disorders, such as sacroiliac joint dysfunction (SIJD). The disorder involves reduced coactivation of the gluteus maximus and contralateral latissimus dorsi, which together provide joint stability during walking. The purpose of our study was to compare the kinematics and contributions of selected muscles to identified synergies during walking between healthy individuals and those with SIJD. Six women with unilateral SIJD and six age-matched healthy controls walked on a force-measuring treadmill at 1 m/s while we recorded kinematics and the activity of 16 muscles with surface EMG. Non-negative matrix factorization was used to identify patterns of EMG activity (muscle synergies). Individuals with SIJD exhibited less hip extension and lower peak vertical ground reaction forces on the affected side than the unaffected side. In contrast to controls, the SIJD group also displayed a depressed muscle synergy between gluteus maximus on the affected side and the contralateral latissimus dorsi. The results indicate that individuals with SIJD exhibited both reduced activation of gluteus maximus during a loading synergy present in walking and greater asymmetry between legs when walking compared with age-matched controls.

Introduction

The sacroiliac joint (SIJ) assists in load transfer from the spine to the lower extremities (Sturesson et al., 1988). As such, it must provide the necessary stability for this force transfer while maintaining a degree of mobility that does not constrain activities of daily living. The joint experiences up to 4800 N of shear force, translates 1.6 mm in the anterior-posterior plane, and may rotate up to 4 degrees while ambulating (Sturesson et al., 1988). When laying supine and performing a straight leg raise, the ilium of the rested leg rotates 0.8 degrees backwards and 0.3 degrees inward (Kibsgård et al., 2017).

To describe the functional stability of this unique joint, Vleeming and colleagues (2012) introduced the principles of form and force closure. Form closure refers to the stability provided by the complimentary convex and concave surfaces of the iliac and sacral joint surfaces. Force closure describes the function of ligaments and muscles acting across the joint to provide joint mobility and stability. A notable component of force closure is the connection from the gluteus maximus to the contralateral latissimus dorsi through the thoracolumbar fascia. This concept suggests that it may be advantageous to have a muscle synergy between these muscles to provide additional stability for the SIJ.

Load transfer through the pelvis with an unstable SIJ, due to compromised form or force closure, can produce excessive loads on surrounding tissues that results in pain (Pool-Goudzwaard et al., 1998). Additionally, SIJ pain can lead to ineffective muscle recruitment, preventing necessary force closure of the joint to maintain stability (Agarwal et al., 2014). The consequence of these changes may result in abnormal joint loading, which influences the control of muscle forces and limb coordination, and is associated with joint degeneration (Herzog et al., 2003, McCrory et al., 2001).

Sacroiliac joint dysfunction (SIJD) causes debilitating pain that impairs mobility (Cher et al., 2014) and is thought to be the etiology of 15–30% of lower back pain (Bernard and Kirkaldy-Willis, 1987, Sembrano and Polly, 2009). In addition to pain at the actual joint, symptoms of SIJD often include pain in the low back and hip, which can reduce muscle strength and endurance, disrupt muscle coordination, and compromise gait patterns (Falla and Hodges, 2017, Graven-Nielsen et al., 1997).

Previous studies have shown that individuals with SIJD preferentially load their unaffected leg and exhibit lower peak hip moments and joint angles on their affected side when standing up from a chair (Capobianco et al., 2018). These altered movement patterns may be an attempt to reduce the amplitude and velocity of a painful movement, or to avoid it altogether (Hodges and Smeets, 2015). To date, no studies have evaluated how SIJD affects kinematics and muscle activation patterns during walking.

We applied a muscle synergy analysis to quantify the relative activities of selected trunk and leg muscles in individuals with SIJD during walking. A muscle synergy comprises a group of muscles that perform complimentary actions and can be activated with simple control strategies (Clark et al., 2010, Lee and Seung, 2001, Lee, 1984, Olree and Vaughan, 1995, Tresch and Jarc, 2009). Muscle synergies can be quantified by applying a factorization analysis, such as non-negative matrix factorization (NMF) (Lee and Seung, 2001, Lee and Seung, 1999), to electromyographic (EMG) data recorded during a cyclic task and identifying muscles with similar activation patterns (Cappellini, 2006, Clark et al., 2010, Oliveira et al., 2014, Ting and Macpherson, 2005, Tresch and Jarc, 2009). The NMF algorithm factors the original EMG signals into two vectors: timing and muscle weighting. Muscles that are activated with similar spatiotemporal patterns are grouped into a synergy with the relative contribution of each muscle indicated by its weight.

Locomotion studies have found that three to five muscle synergies can account for 90% of the variance in EMG signals from many limb and trunk muscles during walking and running (Cappellini, 2006, Olree and Vaughan, 1995). For example, Olree and Vaughan (1995) characterized the muscle synergies required to reconstruct the original EMG signals as contributing to either a propulsion or loading function during walking. In this way, the neural control of locomotion can be reduced to activating groups of muscles rather than individual muscles. Muscle synergy analysis has proven useful in clinical studies to understand how individuals improve their walking performance while recovering from a stroke (Clark et al., 2010) and how persons with spinal cord injury can recover reaching movements (Milosevic et al., 2017, Seelen et al., 1998). Although multiple studies suggest low back pain alters muscle activation patterns (Falla and Hodges, 2017, Hanada et al., 2011, van den Hoorn et al., 2015, van Dieën et al., 2017), no studies to date have examined muscle activation strategies of individuals with SIJD during gait. This information could provide clinicians with insight into how individuals with SIJD adapt to the pain and could inform future treatment plans.

The purpose of our study was to compare the kinematics and contributions of selected muscles to identified synergies during walking between healthy individuals and those with SIJD. We hypothesized that individuals with SIJD would present with a depressed muscle synergy involving gluteus maximus on the affected side and contralateral latissimus dorsi when walking and that the timing of this muscle synergy would be more variable than that in control subjects. Moreover, we hypothesized individuals with SIJD would exhibit greater asymmetry in joint angles and ground reaction forces between legs.

Section snippets

Materials and methods

Six women (age = 37.2 ± 5.9 yrs, BMI = 29.5 ± 5.0) who were diagnosed with unilateral SIJD (2 left side, 4 right side) and six healthy age-matched women (age: 38.8 ± 7.0 yrs, BMI = 21.3 ± 5.9) agreed to participate in the study. The individuals in the SIJD group were free of neurological disorders, without surgery to the lower limbs or back, and were not currently pregnant or pregnant within the past two years. None of the participants indicated that their pain began in the peri-partum period.

Results

All comparisons were made using data collected at 1 m/s as each group had significantly different preferred walking speeds (SIJD group = 0.8 m/s, control group = 1.3 m/s; p = 3.8 × 10^−5). Representative vertical ground reaction force (VGRF) and hip angles during a single stride on each side are shown in Fig. 2. Individuals with SIJD exhibited lower peak VGRF and lower peak hip extension angles on their affected side compared with the unaffected side (Table 1). On average, differences between

Discussion

Similar to previous findings, a muscle synergy between the gluteus maximus and contralateral latissimus dorsi was present on both sides during the loading response in control participants (Olree and Vaughan, 1995). However, consistent with our hypothesis, the gluteus maximus and latissimus dorsi contribution to this synergy was significantly depressed in women with SIJD. In contrast to our second hypothesis, however, the timing of this synergy was not more variable in individuals with SIJD than

Conclusion

Women with SIJD walk with greater asymmetries and exhibit a reduced contribution from the muscle synergy involving gluteus maximus on their affected side. Although women with SIJD exhibit the same number of synergies as healthy women when walking at the same speed, the results of our study are consistent with the hypothesis that the synergy between gluteus maximus on the affected side and the contralateral latissimus dorsi is compromised in individuals with SIJD. Moreover, differences in

Conflict of interest

No authors report a conflict of interest for this work.

Daniel Feeney graduated the University of Colorado Boulder with his Ph.D. in Integrative Physiology and his research interests are the neuromechanical basis of human movement.

References (44)

  • M. Milosevic et al.

    Muscle synergies reveal impaired trunk muscle coordination strategies in individuals with thoracic spinal cord injury

    J. Electromyogr. Kinesiol.

    (2017)
  • A.L. Pool-Goudzwaard et al.

    Insufficient lumbopelvic stability: a clinical, anatomical and biomechanical approach to “a-specific” low back pain

    Man. Ther.

    (1998)
  • H.A. Seelen et al.

    Development of new muscle synergies in postural control in spinal cord injured subjects

    J. Electromyogr. Kinesiol.

    (1998)
  • F. Sibella et al.

    Biomechanical analysis of sit-to-stand movement in normal and obese subjects

    Clin. Biomech. Bristol Avon

    (2003)
  • K.M. Szadek et al.

    Diagnostic validity of criteria for sacroiliac joint pain: a systematic review

    J. Pain

    (2009)
  • M.C. Tresch et al.

    The case for and against muscle synergies

    Curr. Opin. Neurobiol.

    (2009)
  • H. Tsao et al.

    Driving plasticity in the motor cortex in recurrent low back pain

    Eur. J. Pain

    (2010)
  • P.J. Barker et al.

    Anatomy and biomechanics of gluteus maximus and the thoracolumbar fascia at the sacroiliac joint: Anatomy & Biomechanics of Gluteus Maximus

    Clin. Anat.

    (2014)
  • T.N. Bernard et al.

    Recognizing specific characteristics of nonspecific low back pain

    Clin. Orthop.

    (1987)
  • R.A. Capobianco et al.

    Sacroiliac joint dysfunction patients exhibit altered movement strategies when performing a sit-to-stand task

    Spine J. Off. J. North Am. Spine Soc.

    (2018)
  • G. Cappellini

    Motor patterns in human walking and running

    J. Neurophysiol.

    (2006)
  • D. Cher et al.

    Sacroiliac joint pain: burden of disease

    Med. Devices Auckl. NZ

    (2014)
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    Daniel Feeney graduated the University of Colorado Boulder with his Ph.D. in Integrative Physiology and his research interests are the neuromechanical basis of human movement.

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