A model of dynamic sacro–iliac joint instability from malrecruitment of gluteus maximus and biceps femoris muscles resulting in low back pain

https://doi.org/10.1016/j.mehy.2005.02.035Get rights and content

Summary

The objective of this work is to propose a biomechanical model of sacro–iliac joint dysfunction as a cause of low back pain. Sacro–iliac joint is known to be a source of low back pain. We also know that it is a very stable joint with little mobility. Surrounding lower limb and back muscles contribute a major part of this stability. Gait analysis studies have revealed an orderly sequence of muscle activation when we walk – that contributes to efficient stabilisation of the joint and effective weight transfer to the lower limb. Gluteus maximus fibres-lying almost perpendicular to the joint surfaces are ideally oriented for this purpose. Biceps femoris is another important muscle that can also influence joint stability by its proximal attachment to sacrotuberous ligament. Altered pattern of muscle recruitment has been observed in patients with low back pain. But we do not know the exact cause–effect relationship. Because of its position as a key linkage in transmission of weight from the upper limbs to the lower, poor joint stability could have major consequences on weight bearing. It is proposed that sacro–iliac joint dysfunction can result from malrecruitment of gluteus maximus motor units during weight bearing. This results in compensatory biceps over activation. The resulting soft tissue strain and joint instability may manifest itself in low back pain. If our hypothesis holds true, it may have positive implications for patients with sacro–iliac joint dysfunction – who could be offered a definite diagnosis and targeted physiotherapy. It may be possible to identify patients early in a primary care setting and offer direct physio referral. They could benefit from exercises to improve strengthening and recruitment of the affected muscles.

Section snippets

Background

A vast majority of patients with low back pain (LBP) are known to suffer from “Mechanical back pain” – where no clear diagnosis is established. Yet LBP affects up to 70% of the population in developed countries, accounting for an important cause of time off work [1]. The term “sacro–iliac (SI) joint dysfunction” is reserved for cases where no demonstrable pathology is found in the joint, but the joint is presumed to be biomechanically incompetent in effectively transmitting load to the lower

The hypothesis

It is proposed that abnormal force closure of the SI joint results from inappropriate activation of gluteus maximus during gait resulting in LBP. Gluteus contraction stabilises the SI joint. Gluteus is strongly active when we experience abrupt limb loading and need a stable sacro–iliac joint. Sub-optimal gluteus activity would disrupt weight transference. The resulting disruption in force closure would rob the supporting limb of an important shock absorbing mechanism at the SI joint during

Evaluation of the hypothesis

Comparing muscle activation pattern between a group of symptomatic volunteers and a control group can test the hypothesis. The design of the project should involve identification of the timing of onset of electromyographic (EMG) activity of gluteus maximus and biceps femoris muscles in association with different events of the gait cycle. The hypothesis would be validated if there were a significant difference in recruitment pattern of these two muscles between the two groups.

Relevance to clinical practice

It is difficult to state how many of the patients suffering from low back pain have sacro–iliac joint dysfunction. Estimates vary from 2% to 20% [11]. Conservative management is the keystone of treatment in low back pain [12]. But is there a clear margin of benefit? Low back pain patients represent a heterogeneous population group. It has been argued that in order to derive positive outcome from physiotherapy we need further research into subgroups of patients who might respond best from

Discussions

The role SI joint dysfunction as a cause of low back pain is a subject of lively debate [14]. But double block joint injection technique has confirmed that the joint is indeed a source of posterior pelvic pain [11]. The hypothesis is built on known observations that confirm a stable joint with little mobility, the biomechanical reasons behind the need for great stability of the joint, and the ability of certain muscles surrounding the joint to influence stability. We also take into account the

References (14)

There are more references available in the full text version of this article.

Cited by (53)

  • Modifying the hip abduction angle during bridging exercise can facilitate gluteus maximus activity

    2016, Manual Therapy
    Citation Excerpt :

    Hip flexor stiffness, weakness of the GM, deficits in abdominal muscle control, and dominance of ES muscle activity are possible contributing factors for the unwanted excessive lumbar lordosis and anterior pelvic tilts that can occur during bridging (Sahrmann, 2002). GM weakness is one of the common characteristics of patients with low back pain (LBP) (Hossain and Nokes, 2005). Therefore, when bridging exercise are provided to LBP patients with GM weakness, bridging with 30° of hip abduction would be appropriate of preventing unwanted excessive lumbar and pelvic motion (Sahrmann, 2002; Massoud Arab et al., 2011).

  • Isometric hip abduction using a Thera-Band alters gluteus maximus muscle activity and the anterior pelvic tilt angle during bridging exercise

    2015, Journal of Electromyography and Kinesiology
    Citation Excerpt :

    Hip extensors, especially the GM, are important for many functional activities of daily living such as moving from sitting to standing, climbing stairs, and maintaining an upright posture during walking (Winter, 1991). Because the direction of the GM muscle fibers, especially deep sacral fibers of the GM, are perpendicular to the sacroiliac (SI) joint, GM contraction improves SI joint stability and plays a part in force transmission from the lower extremity to the pelvis during ambulation (Hossain and Nokes, 2005; Leinonen et al., 2000; Mooney et al., 2001). However, the GM is frequently weak and lengthened because many people spend a great amount of time remaining seated (Sahrmann, 2002).

View all citing articles on Scopus
View full text