Abstract
BackgroundMany studies suggest that impairment of motor control is the mechanical component of the pathogenesis of painful disorders in the lumbo-sacral region; however, this theory is still unproven and the results and recommendations for intervention remain questionable. The need for a force to compress both innominate bones against the sacrum is the basis for treatment of pregnancy-related pelvic girdle pain (PGP). Therefore, it is advised to use a pelvic belt and do exercises to enhance contraction of the muscles which provide this compression. However, our clinical experience is that contraction of those muscles appears to be excessive in PGP. Therefore, in patients with long-lasting pregnancy-related posterior PGP, there is a need to investigate the contraction pattern of an important muscle that provides a compressive force, i.e. the transverse abdominal muscle (TrA), during a load transfer test, such as active straight leg raising (ASLR).MethodsTrA thickness was measured by means of ultrasound imaging at rest and during ASLR in 43 non-pregnant women with ongoing posterior PGP that started during a pregnancy or delivery, and in 39 women of the same age group who had delivered at least once and had no current PGP (healthy controls).ResultsIn participants with PGP, the median TrA thickness increase with respect to rest during ipsilateral and contralateral ASLR was 31% (SD 46%) and 31% (SD 57%), respectively. In healthy controls, these values were 11% (SD 25%) and 13% (SD 22%), respectively.ConclusionsSignificant excessive contraction of the TrA is present during ASLR in patients with long-lasting pregnancy-related posterior PGP. The present findings do not support the idea that contraction of the TrA is decreased in long-lasting pregnancy-related PGP. This implies that there is no rationale for the prescription of exercises to enhance contraction of TrA in patients with long-lasting pregnancy-related PGP.
Highlights
Many studies suggest that impairment of motor control is the mechanical component of the pathogenesis of painful disorders in the lumbo-sacral region; this theory is still unproven and the results and recommendations for intervention remain questionable
Biomechanical and anatomical studies have shown that transversely-oriented muscles of the abdominal wall, especially the transverse abdominal muscle (TrA), in cocontraction with the pelvic floor, are the most suitable muscles to achieve compression of both innominate bones against the sacrum (‘force closure’ of the sacroiliac joints) and could, theoretically, reduce movement in the sacroiliac joints and the strain on the engaged ligaments [3,4,5,6]
Patients with pelvic girdle pain (PGP) were about 4 years younger than controls, and duration since postpartum was shorter by about 4 years
Summary
Many studies suggest that impairment of motor control is the mechanical component of the pathogenesis of painful disorders in the lumbo-sacral region; this theory is still unproven and the results and recommendations for intervention remain questionable. The need for a force to compress both innominate bones against the sacrum is the basis for treatment of pregnancy-related pelvic girdle pain (PGP). The theory of compromised motor control to explain the development of LPP proposes that many activities create (small) movements in the lumbopelvic region, which subsequently induce strain on the ligaments and pain. The theory implies that the more efficiently individuals contract those muscles, the better they protect themselves against the strain on the ligaments in the pelvic ring, resulting in a lower risk to develop PGP and a greater chance to recover from it. Some studies published after that review (e.g. Beazell et al, 2011; Himes et al, 2012; Pinto et al, 2011) found no significant difference in TrA contraction between patients with LPP and controls [8,9,10,11]. In most studies, maximal voluntary muscle contraction was investigated instead of spontaneous, automatic recruitment of muscles during a well-defined task
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