Authors' response to the letter to the <scp>E</scp>ditors by <scp>P</scp>rofessor <scp>M</scp>. <scp>T</scp>. <scp>C</scp>ibulka: a critical interpretation of sacroiliac joint movement studies

Vleeming, Adriaan; Schuenke, Mark D.; Sturesson, Bengt; Willard, Frank H.

doi:10.1111/joa.12018

Cited by 4 publications

(6 citation statements)

References 37 publications

(43 reference statements)

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“…The supposingly shorter lever arm of the COG to the SIJs in girls at pre-PHV age, conversely, may allow more mobility in the female SIJs. The increased SIJ mobility in postpubescent females over males (Sturesson et al, 1989;Vleeming et al, 2012Vleeming et al, , 2013 can be considered functional in allowing passage for a child during labor. However, an increased mobility may also lead to complaints of pelvic pain if it is not compensated for by adequate force closure and/or neuromuscular control (Vleeming et al, 2008;Arumugam et al, 2012).…”

Section: Discussionmentioning

confidence: 99%

“…A third compensatory mechanism to (increased) biomechanical loading is the potential of bone and joints to adapt to the mechanical forces they are exposed to in life during normal function (Masharawi et al., ; Vleeming et al., ). Highly relevant in this regard is the tenet that morphological traits and biomechanics are linked by causal morphogenesis (‘Wolff's law’) and the interplay of mutations and selection (Masi et al., ; Preuschoft, ; Whitcome et al., ; Vleeming et al., , ). Although our data concerning gender‐specificity in sagittal standing alignment in healthy subjects before pubertal peak growth do not allow definitive conclusions to be made as to which of the known sexual dimorphisms in the spinal‐pelvic region should be considered functional adaptations to cope with the mechanical stresses of daily life or which rather would have an evolutionary selective cause (e.g.…”

Section: Discussionmentioning

confidence: 99%

“…Consequently, the larger distance between the assumed rotational point of the SIJ and the vertical through the COG in pre‐PHV boys that was found in the present study, may argue that male SIJ development is likely to be a functional adaptation to cope with major forces and increased biomechanical loading. While the proposed functional adaptation in the male SIJ may enhance form closure in men, it may limit the joint mobility as well (Schuncke, ; Vleeming et al., , , ). Accordingly, the mean SIJ mobility in men with a longer lever arm and stronger SIJs was shown to be on average 30–40% smaller compared with women (Sturesson et al., ; Vleeming et al., , ).…”

Section: Discussionmentioning

confidence: 99%

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Gender differences in sagittal standing alignment before pubertal peak growth: the importance of subclassification and implications for spinopelvic loading

et al. 2013

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The aim of this study was to analyze gender differences in sagittal standing alignment at pre-peak height velocity age thereby applying a scientifically sound and practically oriented classification scheme for overall standing balance. The study population consisted of healthy boys (n = 639) and girls (n = 557) before pubertal peak growth. During subjects' habitual standing, sagittal plane measures of the spine, pelvis and lower limbs were collected using a clinical screening protocol. With each subject classified as one of three postural types (neutral, sway-back, or leaning-forward), differences in sagittal plane alignment were analyzed between sexes. The results revealed clear differences between genders in each of the postural types. Within the neutral and sway-back postural subgroups, boys presented more forward inclination of the trunk, more thoracic kyphosis and more pelvis backtilt compared with girls. Within the leaning-forward category, girls displayed more forward trunk lean, less thoracic kyphosis and more pelvic anteversion. A state of lumbar segmental hyperextension appeared to exist in female leaning-forward subjects. Our results reveal for the first time that sagittal standing alignment is different between prepubescent boys and girls when subjects are appropriately subclassified, and conversely represent a 'wash-out effect' when pooled. When the classification system is applied, gender-specificity in gravity line position is suggested, implying gender-related differences in lever arms and thus load. Present findings may add to our understanding of gender-specific biomechanical challenges posed by habitual posture, and may shed new light on sagittal standing alignment as a possible contributory factor in developmental spinal-pelvic disorders.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Gender differences in sagittal standing alignment before pubertal peak growth: the importance of subclassification and implications for spinopelvic loading

et al. 2013

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“…Biomechanical studies have shown that the TrA and oblique abdominal muscles pull the anterior portion of the anterior superior iliac spine (ASIS) toward each other, which results in increased pressure in the SIJ and pubic symphysis. In turn, this contributes to increased force closure of the pelvis in upright posture . The active straight leg test is a physical examination test that assesses, in part, this mechanism.…”

Section: A Biomechanical Model For Force Closing the Pelvic Joints Inmentioning

confidence: 99%

“…While in the supine position the patient reports the ability to actively raise each leg in a straightened position and then self‐reports a grade of 0 (normal ability) to grade 5 (unable to lift the leg). The examiner then applies anterior compression to the ASIS to assist with the self‐bracing mechanism of the pelvis and, in most cases, the patient will report an improved ability to lift the leg …”

Section: A Biomechanical Model For Force Closing the Pelvic Joints Inmentioning

confidence: 99%

Form and Force Closure of the Sacroiliac Joints

Vleeming

Schuenke

2019

PM&R

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The principles of form and force closure were introduced to describe the complex mechanism of sacroiliac joint (SIJ) stability. Form closure refers to a theoretical stable state of a joint with close fitting articular surfaces, where no extra forces are needed to maintain the stable state of the system during loading and unloading situations. If the sacrum would fit in the pelvis with perfect form closure, no lateral compressional forces would be needed to maintain stability. However, such a construction would make mobility practically impossible. Force closure is the theoretical state where lateral force and friction resulting in joint compression, are required for the joint to withstand a vertical load. Structures that contribute to SIJ stability via “form closure” include (1) the configuration of the interfacing joint surfaces, along with dorsocranial “wedging” of the sacrum into the ilia; (2) the corresponding ridges and grooves of the articular surfaces of the SIJs and resultant high coefficient of friction; and (3) the integrity of the binding ligaments, which are among the strongest in the body. Shearing forces absorbed in the SIJ occur because of a combination of person‐specific anatomical features. This results in unique form and force closure situations that provide effective and tailored joint accommodation that balance both friction and compression in the joint. Force closure occurs because of altered joint reaction force via taut ligaments, fascia, muscles, and the ground reaction force they are reacting to at the moment. In the ideal state, force closure creates a perpendicular compressive reaction force to the SIJ to adapt and overcome the forces of gravity. In order for force closure to be effective, sacral nutation must occur and is considered to be anticipatory for joint loading. Sacral nutation results in tensing all of the dorsal SIJ ligaments (interosseous, dorsal sacroiliac) with the exception of one, the long dorsal ligament (LDL). This prepares the pelvis to absorb and increase in load. As a result, the posterior ilium are pressed together causing an increase in SIJ compression. This review will discuss the importance of understanding form and force closure principles because they are related to understanding the relationship of anatomy and function of the SIJ.

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Two-leg alternate loading model – A different approach to biomechanical investigations of fixation methods of the injured pelvic ring with focus on the pubic symphysis

Agarwal¹,

Doebele²,

Windolf³

et al. 2014

Journal of Biomechanics

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Authors' response to the letter to the Editors by Professor M. T. Cibulka: a critical interpretation of sacroiliac joint movement studies

Cited by 4 publications

References 37 publications

Gender differences in sagittal standing alignment before pubertal peak growth: the importance of subclassification and implications for spinopelvic loading

Gender differences in sagittal standing alignment before pubertal peak growth: the importance of subclassification and implications for spinopelvic loading

Form and Force Closure of the Sacroiliac Joints

Two-leg alternate loading model – A different approach to biomechanical investigations of fixation methods of the injured pelvic ring with focus on the pubic symphysis

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