Elsevier

Clinical Biomechanics

Volume 19, Issue 5, June 2004, Pages 456-464
Clinical Biomechanics

Altered patterns of pelvic bone motion determined in subjects with posterior pelvic pain using skin markers

https://doi.org/10.1016/j.clinbiomech.2004.02.004Get rights and content

Abstract

Objective. To determine whether the pattern of pelvic bone motion, determined by skin markers, differs between control subjects and subjects with posterior pelvic pain.

Design. Cross-sectional study of three-dimensional angular and translational motion of the innominates relative to the sacrum in two subject groups.

Background. Comparative in vivo analysis of the 3D patterning of pelvic motion in subjects with posterior pelvic pain and controls is limited.

Methods. Fourteen males with posterior pelvic pain and healthy age and height matched controls were studied. A 6-camera motion analysis system was used to determine 3D angular and translational motion of pelvic skin markers during standing hip flexion.

Results. Posterior rotation of the innominate occurred with hip flexion in control subjects and pelvic pain subjects as previously reported in the literature. On the supporting leg, the innominate rotated posteriorly in controls and anteriorly in symptomatic subjects.

Conclusion. Posterior rotation of the innominate, as measured using skin markers during weight bearing in controls may reflect activation of optimal lumbo-pelvic stabilisation strategies for load transfer. Anterior rotation occurred in symptomatic subjects, suggesting failure to stabilise intra-pelvic motion for load transfer.
Relevance

This study found that posterior rotation of the innominate occurred during weight bearing in controls. This movement pattern is thought to optimise stability of the pelvic girdle during increased loading. Conversely, anterior rotation occurred in symptomatic subjects during weight bearing. This is a non-optimal pattern and may indicate abnormal articular or neuromyofascial function during increased vertical loading through the pelvis.

Introduction

A primary function of the lumbar spine and pelvis is to transfer the loads generated by body weight and gravity during standing, walking and sitting (Snijders et al., 1993). How well this load is managed dictates the efficacy of function. A small amount of motion occurs at the sacroiliac joints (SIJ) and the pubic symphysis during movements of the trunk and lower limbs (Jacob and Kissling, 1995; Walheim and Selvik, 1984). Consequently, during weight bearing activities, control (stabilisation) of intra-pelvic motion is required for transference of loads between the spine and the lower limbs (Snijders et al., 1993; Vleeming et al., 1990). According to Panjabi (1992) stability is achieved when the passive, active and control systems work together. Snijders et al. (1993) suggests that the passive, active and control systems produce approximation of the joint surfaces, essential if stability is to be insured. The amount of approximation required is variable and difficult to quantify as it is dependent on an individual's structure (form closure) and the forces they need to control (force closure). The ability to effectively transfer load through the pelvis is dynamic and therefore depends on: (1) optimal function of the bones, joints and ligaments (Vleeming et al., 1989, Vleeming et al., 1990); (2) optimal function of the muscles and fascia (Hungerford et al., 2003; Richardson et al., 2002; Snijders et al., 1998; Vleeming et al., 1995a, Vleeming et al., 1995b); (3) appropriate neural function (Hodges and Richardson, 1997; Hungerford et al., 2003).

For every joint, there is a position called the self-braced (close-packed) position in which there is maximum congruence of the articular surfaces and maximum tension on major ligaments. In this position, the joint is under significant compression and the ability to resist shear forces is enhanced by tensioning of the passive structures and increased friction between the articular surfaces (Snijders et al., 1993; Vleeming et al., 1990). The self-braced position of the SIJ is nutation of the sacrum or posterior rotation of the innominate (Vleeming et al., 1989). Studies have shown (Sturesson et al., 2000) that nutation of the sacrum relative to posterior rotation of the innominate occurs bilaterally whenever the lumbo-pelvic spine is loaded vertically (sitting, standing). Counternutation of the sacrum, or anterior rotation of the innominate, is thought to be a relatively less stable position for the SIJ (Vleeming et al., 1995b). The long dorsal ligament becomes taut during this motion, however tension in other ligaments such as sacrotuberous and interosseous ligaments decreases (Vleeming et al., 1996).

At present there is only limited research comparing the in vivo pattern of pelvic motion during weight bearing and non-weight bearing activities. This is due to the invasiveness of the most reliable and valid methods of analysis, consequential ethical considerations for using invasive procedures to evaluate large number of subjects and difficulty in evaluating the small amplitude of in vivo SIJ motion. When an individual stands on one leg and flexes the contralateral hip, the non-weight bearing innominate posteriorly rotates relative to the sacrum (range of motion 0.1–5.0°) (Jacob and Kissling, 1995; Sturesson et al., 2000). Side flexion and axial rotation of the innominate occur concurrently about sagittal and vertical axes respectively. Translation (motion along the sagittal, vertical and/or coronal axes) also occurs (Jacob and Kissling, 1995; Sturesson et al., 2000), although the specific direction of translation that occurs with angular motion is not fully understood. It has been hypothesised (Lee, 1999) that anterior and superior translation of the innominate, relative to the sacrum, will occur with posterior rotation of the innominate.

Buyruk et al. (1995) and Damen et al. (2002) established that a Doppler imaging system was able to measure stiffness of the SIJ. This research showed that stiffness of the SIJ is variable between subjects and therefore the range of motion is potentially variable. It also revealed that stiffness of right and left SIJs is symmetric in subjects without pelvic pain. The results support putting less emphasis on amplitude of motion and more on the pattern or symmetry of SIJ, or pelvic motion, as range of motion varies between subjects, however within one subject joint stiffness remains symmetric between sides.

The SIJs and the posterior SIJ ligaments are a known source of posterior pelvic pain (Fortin et al., 1994; Vleeming et al., 2002). Jacob and Kissling (1995) noted that in the presence of SIJ symptoms, the amplitude of SIJ motion about a coronal axis increased during hip flexion in one subject. Mens et al. (1999) determined increased amplitude of anterior rotation of the innominate in posterior pelvic pain patients. Sturesson et al. (2000) reported no difference in the amplitude or pattern of either angular or translational motion of the innominates when the left and right SIJs were compared in subjects with posterior pelvic pain. No comparison was made with an asymptomatic group. Hungerford et al. (2003) showed that posterior pelvic pain alters the pattern of lumbo-pelvic muscle recruitment, while Buyruk et al. (1999) and Damen et al. (2002) showed that stiffness of the SIJ is asymmetric in subjects with pelvic pain and that asymmetrical stiffness of the SIJs is prognostic for pelvic impairment and pain. It is presently unknown if posterior pelvic pain alters the patterning of bone motion within the pelvis for single leg stance.

The supine active straight leg raise test (ASLR) (Mens et al., 2001) has been validated as a clinical test for measuring effective load transfer between the trunk and lower limbs. When the lumbo-pelvic region is functioning optimally, the leg should rise effortlessly from the table (effort graded from 0 to 5) (Mens et al., 1999). A correlation has been shown between positive ASLR findings and posterior pelvic pain (Mens et al., 1999; O'Sullivan et al., 2002). Similarly, Damen et al. (2001) and Buyruk et al. (1999) showed that the ASLR is positive in the presence of asymmetric stiffness of the SIJ. This suggests that altered pelvic stabilisation strategies may affect pelvic mobility (Buyruk et al., 1999; Damen et al., 2001).

A non-invasive motion analysis system using skin mounted markers was chosen to acquire the kinematic data of pelvic bone motion during a standing hip flexion movement for ethical reasons. Errors in determining the range of motion are likely to occur with an optoelectronic system due to skin marker motion relative to underlying bony landmarks (Maslen and Ackland, 1994). A high resolution motion analysis system has however been reported to provide reliable and consistent in vivo data of lumbar segmental motion patterns (Gracovetsky et al., 1995). In this study, the authors recognise that the movements noted reflect motion of the innominates, sacrum, and femurs in conjunction with overlying skin, and therefore the main emphasis of this study was to investigate the patterns of bone motion rather than the range of motion.

The aim of this study was to determine the three-dimensional pattern of innominate bone motion occurring in subjects determined to have posterior pelvic pain and impaired pelvic stabilisation strategies during weight bearing and non-weight bearing components of a standing hip flexion movement. These results were compared to age and height matched controls with clinically assessed normal pelvic stabilisation and pelvic motion patterns. It was hypothesised that the pattern of innominate bone motion would alter in subjects with posterior pelvic pain during both components of the movement trial.

Section snippets

Impaired pelvic stabilisation and posterior pelvic pain group

Fourteen male subjects with SIJ pain and a mean (range) age, height and weight of 32.7 (24–47) years, 176.8 (168–184) cm, and 77.0 (71–90) kg respectively, volunteered for the study. The criteria for inclusion in this study were:

  • 1.

    Each subject in the posterior pelvic pain group reported unilateral pain over the posterior pelvic/SI region (Fortin et al., 1994) for greater than two months, and no pain above the lumbo-sacral junction. The pain was consistently and predictably aggravated by

Results

The pattern of angular and translational motion of each innominate segment, relative to the sacral segment, was measured during a standing hip flexion movement using a non-invasive method. Possible errors in determining the magnitude of pelvic bone motion may have occurred due to the movement of skin markers over bony landmarks, therefore the emphasis of this study was on changes to the patterns of pelvic bone motion as reflected by the measured skin marker movement.

Discussion

Significant differences were found in the pattern of pelvic bone motion that occurred during standing hip flexion when intra-subject (between weight bearing and non-weight bearing sides) and inter-subject (between the control group and posterior pelvic pain group) comparisons were made. The range of motion reported between the innominate and sacral segments, as determined using motion analysis, was generally larger than the range of motion determined during analysis of SIJ motion using

Conclusions

The most significant alteration to the pattern of bone motion between controls and subjects with posterior pelvic pain occurred on the side of single leg support. In the control subjects, the weight bearing innominate posteriorly rotated and translated superiorly, posteriorly and medial relative to the sacral segment. In the subjects with posterior pelvic pain, the weight bearing innominate anteriorly rotated and translated inferiorly. The results of this study suggest that posterior rotation

Acknowledgements

The technical assistance of Ray Patton and Dr. Richard Smith from the School of Exercise and Sports Science, University of Sydney is acknowledged.

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