Rob Stoeckart

The posterior layer of the thoracolumbar fascia : its function in load transfer from spine to legs

Study Design The superficial and deep lamina of the posterior layer of the thoracolumbar fascia have been studied anatomically and biomechanically. In embalmed human specimens, the posterior layer has been loaded by simulating the action of various muscles. The effect has been studied using raster photography. Objectives To study the role of the posterior layer of the thoracolumbar fascia in load transfer between spine, pelvis, legs, and arms. Summary of Background Data It has been determined whether muscles such as the gluteus maximus, latissimus dorsi, erector muscle, and biceps femoris are functionally coupled via the thoracolumbar fascia. The caudal relations of the posterior layer of the thoracolumbar fascia have not been previously studied. Methods Dissection was directed to the bilaminar posterior layer of the thoracolumbar fascia of 10 human specimens. The superficial and deep lamina were studied using visual inspection and raster photography. Tension to the posterior layer of the fascia was simulated by traction to various muscles and measured by studying the displacement in the posterior layer. Results Traction to a variety of muscles caused displacement of the posterior layer. This implies that in vivo, the superficial lamina will be tensed by contraction of various muscles, such as the latissimus dorsi, gluteus maximus and erector muscle, and the deep lamina by contraction of the biceps femoris. Caudal to the level of L4 (in some specimens, L2-L3), tension in the posterior layer was transmitted to the contralateral side. Conclusions Anatomic structures normally described as hip, pelvic, and leg muscles interact with socalled arm and spinal muscles via the thoracolumbar fascia. This allows for effective load transfer between spine, pelvis, legs, and arms-an integrated system. Specific electromyographic studies should reveal whether the gluteus maximus muscle and contralateral latissimus dorsi muscle are functionally coupled, especially during rotation of the trunk. In that case, the combined action of these muscles assists in rotating the trunk, while simultaneously stabilizing the lower lumbar spine and sacroiliac joints.

Understanding peripartum pelvic pain. Implications of a patient survey.

Study Design. An analysis was made of the self‐reported medical histories of patients with peripartum pelvic pain. Objectives. To compile an inventory of the disabilities of patients with peripartum pelvic pain, analyze factors associated with the risk for development of the disease, and to formulate a hypothesis on pathogenesis and specific preventive and therapeutic measures. Summary of Background Data. Pregnancy is an important risk factor for development of chronic low back pain. Understanding the pathogenesis of pelvic and low back pain during pregnancy and delivery could be useful in understanding and managing nonspecific low back pain. Methods. By means of a questionnaire, background data were collected among patients of the Dutch Association for Patients With Pelvic Complaints in Relation to Symphysiolysis. Results were compared with the general population. Subgroups were compared with each other. Results. Peripartum pelvic pain seriously interferes with many activities of daily living such us standing, walking, sitting, and all other activities in which the pelvis is involved. Most patients experience a relapse around menstruation and during a subsequent pregnancy. Occurrence of peripartum pelvic pain was associated with twin pregnancy, first pregnancy, higher age at first pregnancy, larger weight of the baby, forceps or vacuum extraction, fundus expression, and a flexed position of the woman during childbirth; a negative association was observed with cesarean section. Conclusions. It is hypothesized that peripartum pelvic pain is caused by strain of ligaments in the pelvis and lower spine resulting from a combination of damage to ligaments (recently or in the past), hormonal effects, muscle weakness, and the weight of the fetus.

Relation Between Form and Function in the Sacroiliac Joint: Part I: Clinical Anatomical Aspects

Observations on sectioned and opened preparations of human sacroiliac joints (SI joints) show the presence of cartilage-covered ridges and depressions, which are complementary on the auricular surfaces. These macroscopically visible features of the joints, which become visible relatively early in life, are more pronounced in men than in women. This type of roughening, as well as that by increased coarseness of the auricular surface, is viewed as a nonpathologic adaptation to the forces exerted at the SI joints, leading to increased stability. Differences between men and women may be attributed to childbearing and to a difference in the center of gravity. It is emphasized that intra-articular ridges and depressions can be misinterpreted roentgenologically as osteophytes.

Relation between form and function in the sacroiliac joint. Part II: Biomechanical aspects.

The amount of friction between the articular surfaces of sacroiliac (SI) joints was determined and related to the degree of macroscopic roughening. Results show that articular surfaces with both coarse texture and ridges and depressions have high friction coefficients. The influence of ridges and depressions appears to be greater than that of coarse texture. The data are compatible with the view that roughening of the SI joint concerns a physiologic process.

The function of the long dorsal sacroiliac ligament: Its implication for understanding low back pain

Study Design In embalmed human bodies the tension of the long dorsal sacroiliac ligament was measured during incremental loading of anatomical structures that are biomechanically relevant. Objectives To assess the function of the long dorsal sacroiliac ligament. Summary of Background Data In many patients with aspecific low back pain or peripartum pelvic pain, pain is experienced in the region in which the long dorsal sacroiliac ligament is located. It is not well known that the ligament can be easily palpated in the area directly caudal to the posterior superior iliac spine. Data on the functional and clinical importance of this ligament are lacking. Methods A dissection study was performed on the sacral and lumbar regions. The tension of the long dorsal sacroiliac ligament (n = 12) was tested under loading. Tension was measured with a buckle transducer. Several structures, including the erector spinae muscle, the posterior layer of the thoracolumbar fascia, the sacrotuberous ligament, and the sacrum, were incrementally loaded (with forces of 0‐50 newtons). The sacrum was loaded in two directions, causing nutation (ventral rotation of the sacrum relative to the iliac bones) and counternutation (the reverse). Results Forced nutation in the sacroiliac joints diminished the tension and forced counternutation increased the tension. Tension in the long dorsal sacroiliac ligament increased during loading of the ipsilateral sacrotuberous ligament and erector spinae muscle. The tension decreased during traction to the gluteus maximus muscle. Tension also decreased during traction to the ipsilateral and contralateral posterior layer of the thoracolumbar fascia in a direction simulating contraction of the latissimus dorsi muscle. Conclusions The long dorsal sacroiliac ligament has close anatomical relations with the erector spinae muscle, the posterior layer of the thoracolumbar fascia, and a specific part of the sacrotuberous ligament (tuberoiliac ligament). Functionally, it is an important link between legs, spine, and arms. The ligament is tensed when the sacroiliac joints are counternutated and slackened when nutated. The reverse holds for the sacrotuberous ligament. Slackening of the long dorsal sacroiliac ligament can be counterbalanced by both the sacrotuberous ligament and the erector muscle. Pain localized within the boundaries of the long ligament could indicate among other things a spinal condition with sustained counternutation of the sacroiliac joints. In diagnosing patients with aspecific low back pain or peripartum pelvic pain, the long dorsal sacroiliac ligament should not be neglected. Even in cases of arthrodesis of the sacroiliac joints, tension in the long ligament can still be altered by different structures.

An integrated therapy for peripartum pelvic instability: A study of the biomechanical effects of pelvic belts

OBJECTIVES The objectives of this study were to investigate the influence of pelvic belts on the stability of the pelvis and to discuss the treatment of peripartum pelvic instability. STUDY DESIGN In six human pelvis-spine preparations, sagittal rotation in the sacroiliac joints was induced by bidirectional forces directed at the acetabula. Weight-bearing was mimicked by the application of a compressive force to the spine. The biomechanical effect of a pelvic belt was measured in 12 sacroiliac joints. RESULTS The pelvic belt caused a significant decrease in the sagittal rotation in the sacroiliac joints. The effect of a 100 N belt did not differ significantly from that of a 50 N belt. CONCLUSION The combination of a pelvic belt and muscle training enhances pelvic stability. The load of the belt can be relatively small; location is more important. The risk of symphysiodesis, especially as a result of the insertion of bone grafts, is emphasized.

Upper limb tension tests as tools in the diagnosis of nerve and plexus lesions. Anatomical and biomechanical aspects.

OBJECTIVE To analyse the validity of nerve tension tests used in the diagnosis of nerve (root) and plexus lesions of the upper extremity. DESIGN In six arms of embalmed human bodies, in situ measurements were performed to assess the effect of nerve tension tests on the median, ulnar and radial nerves and the cords of the brachial plexus. BACKGROUND In clinical practice it is useful to have fast, easy and cheap tests for the diagnosis of nerve (root) lesions of the upper extremity, analogous to Lasègues Straight Leg Raising test.Methods. The Upper Limb Tension Tests for the median, ulnar and radial nerves, as well as the Upper Limb Tension Tests combined with contralateral rotation and lateral bend of the cervical spine (Upper Limb Tension Test+) were used to generate tension to these nerves. Buckle force transducers were used to assess tensile forces in the nerves and in the medial, lateral and posterior cords of the brachial plexus. RESULTS Nerve tension introduced in the distal part of the median, ulnar and radial nerves was transmitted upward to the cords of the brachial plexus. Exclusively the median nerve Upper Limb Tension Test and Upper Limb Tension Test+ turned out to be sensitive and specific tension tests. Mechanical tension caused by the Upper Limb Tension Test+ was not significantly higher than that caused by the Upper Limb Tension Tests. The Upper Limb Tension Tests cannot be used to selectively stress cervical nerve roots. The findings justify investigation of exclusively the median nerve Upper Limb Tension Test and Upper Limb Tension Test+ on their clinical validity. RELEVANCE Before nerve tension tests for the median, ulnar and radial nerves can be introduced to clinical practice it is necessary to assess their validity quantitatively.

EMG recordings of abdominal and back muscles in various standing postures: validation of a biomechanical model on sacroiliac joint stability

In a biomechanical model we described that for stability of the flat sacroiliac joints (SIJ) muscle forces are required which press the sacrum between the two hip bones (self-bracing). Shear loading of these joints is caused by gravity and longitudinally oriented muscles. Protection against shearing can come from transversely oriented muscles like the internal oblique (OI) abdominal muscles. For validation we used standing postures with significantly more or less OI activity compared to activity in a standardized erect standing reference posture. OI activity decreased significantly when (a) resting on one leg (the contralateral), as can be observed at bus stops, (b) tilting the pelvic backward and (c) applying a pelvic belt. We explain this decrease of OI activity by, respectively, decrease of gravity load, decrease of load from the psoas major muscles, and a substitute of self-bracing. The outcome of this study is in line with the biomechanical model on SIJ stability. Clinical relevance of this study regards aspecific low back pain and is found in the effect of the use of a pelvic belt, of a trunk position as adopted when wearing a small rucksack and of the benefit of exercising trunk muscles in extension and torsion.

The sacrotuberous ligament: a conceptual approach to its dynamic role in stabilizing the sacroiliac joint

Abstract Based on studies of embalmed specimens, the sacrotuberous ligaments are considered to be important structures in the kinematic chain between the pelvis and vertebral column. Muscles attached to these ligaments, such as the gluteus maximus, and in some individuals the piriformis and long head of the biceps femoris, may influence movement in the sacroiliac joints.

Transfer of lumbosacral load to iliac bones and legs Part 2: Loading of the sacroiliac joints when lifting in a stooped posture

We developed a biomechanical model of load transfer by the sacroiliac joints in relation to posture. A description is given of two ways in which the transfer of lumbar load to the pelvis in a stooped posture can take place. One way concerns ligament and muscle forces that act on the sacrum, raising the tendency of the sacrum to flex in relation to the hip bones. The other refers to ligament and muscle forces acting on the iliac crests, raising the tendency of the sacrum to shift in caudal direction in relation to the hip bones. Both loading modes deal with the self-bracing mechanism that comes into action to prevent shear in the sacroiliac joints. When a person is lifting a load while in a stooped posture, the force raised by gravity acting in a plane perpendicular to the spine and the sacrum becomes of interest. In this situation a belt such as used by weight lifters may contribute to the stability of the sacroiliac joints. Verification of the biomechanical model is based on anatomical studies and on load application to human specimens. Magnetic resonance imaging pictures have been taken to verify geometry in vivo.