Pelvic Biomechanics PDF

Pelvic Biomechanics Prof. Olga Hoyos López MSc PT Osteology of the pelvis: Innominate Each innominate (from the Latin innominatum) is the union of three bones: the ilium, pubis, and ischium The right and left innominates connect with each other anteriorly at...

Pelvic Biomechanics Prof. Olga Hoyos López MSc PT Osteology of the pelvis: Innominate Each innominate (from the Latin innominatum) is the union of three bones: the ilium, pubis, and ischium The right and left innominates connect with each other anteriorly at the pubic symphysis and posteriorly at the sacrum. These connections form a complete osteoligamentous ring, referred to as the pelvis (from the Latin, meaning basin or bowl). 2 Basic Anatomy of the Pelvis Pelvis of a 5-year-old child 3  The pelvis: Basic function The pelvis is associated with three important and very different functions. 1)attachment point for many muscles of the lower extremity and the trunk. 2)transmits the weight of the upper body and trunk either to the ischial tuberosities (sitting) or to the lower extremities (standing and walking) 3)with the aid of the muscles and connective tissues of the pelvic floor, the pelvis supports the organs involved with bowel, bladder, and reproductive functions. 4 The pelvis: Basic anatomy 5  Functional Anatomy of the Pelvis Intrinsic Joints of the Pelvis – Sacrococcygeal joint – Pubic symphysis – SacroIliac joint Extrinsic Joints of the Pelvis – Lumbosacral joint – Acetabulofemoral joint 6  1. Intrinsic Joints of the pelvis: 1.a.Sacrococcygeal joint Between the apex of the sacrum and the base of the coccyx It is a symphysis, having the two bones lined by hyaline cartilage and connected by an interposed fibrous disc. Being a symphysis, the sacrococcygeal joint is only slightly mobile. The movements within the joint are entirely passive and are limited to one degree of freedom; flexion-extension. The function of the sacrococcygeal mobility is to increase the anteroposterior diameter of the pelvis during labor and defecation. 7  1. Intrinsic Joints of the pelvis: 1.b. Pubic symphysis/Interpubic-cartilage The two pubic bones articulate in the midline by way of the pubic symphysis joint. Hyaline cartilage lines the surfaces of the articulation. The joint is firmly bound by a fibrocartilaginous interpubic disc and ligaments. The interpubic disc is strengthened by an interlacing of collagen fibers, combined with distal attachments made by the rectus abdominis muscles. Up to 2 mm of translation and very slight rotation occur at the pubic symphysis joint.The pubic symphysis provides stress relief throughout the anterior ring of the pelvis during walking and, in women, during childbirth. 8  1. Intrinsic Joints of the pelvis: 1.c. Sacro-iliac joint (SIJ) - In childhood the sacroiliac joint has all the characteristics of a synovial joint, being relatively mobile and surrounded by a capsule. Between puberty and adulthood, however, the sacroiliac joint gradually transforms to a modified synarthrodial joint. Functions: - Transition of forces from pelvic to caudal region - SIJ is designed primarily for stability, ensuring effective transfer of potentially large loads between the vertebral column, the lower extremities, and ultimately the ground. 9  SI JOINT STABILITY: LIGAMENTS Primary Stabilizers Anterior Sacroiliac anterior Iliolumbar Posterior Sacroiliac posterior Interosseous Secondary Stabilizers Sacrotuberous ligament Sacrospinous ligament 10  Kinematics of the Pelvis: SIJ Mainly small rotational & translational movements of the SI Joints Movements based on the compression of the articular cartilage and sligth movement between joint surfaces Anthropometric measurements 1-4 dg of rotation and 1-2mm for translation (difficult to measure) Combined with another movement of the lower limb or spine. 11 Kinematics of the SIJ- Nutation and Counternutation Sagittal plane. AP- lateral medial axis. They are not pure movements with absolute degrees of freedom and voluntarily executed. Combined movements and kinematic adjustments between the spine and the lower limb. 12 S.I Kinematics 13  Kinematics of the SIJ- Nutation Nutation: It is defined as the relative anterior tilt of the base (top) of the sacrum, relative to the ilium (forward movement of the base of the sacrum) 14  Kinematics of the S.I- Counternutation Counternutation: Counternutation is a reverse motion defined as the relative posterior tilt of the base of the sacrum relative to the ilium. (movement of the base of the sacrum posteriorly) 15 Kinematics of the S.I- Nutation and Counternutation 16  Functional considerations of Nutation and Counternutation 1. Joint stress relief 2. Stability during load changes 17  1. Joint Stress Relief When we walk, run, give birth: very high mechanical stress on the pelvis. Pelvis generates these movements so that when we are in support phases (load), the SI joint releases the pelvis from joint stress. 18  2.Stability during load changes When we make load changes, fast or heavy, we need stability. The more congruence, the more stability Pelvis in retroversion: more congruence: sacrum in nutation.All the forces that go towards nutation will help stabilize the SIJ (close pack position=full nutation) 19 Stability during load changes 20  Stability during load changes: Kinetics Muscles that reinforce and stabilize the SIJ -Erector spinae -Lumbar multifidi -Abdominal muscles Rectus abdominis Obliquus abdominis internus and externus Transversus abdominis -Hip extensor muscles (such as biceps femoris and gluteus maximus) -Latissimus dorsi -Iliacus and piriformis 21  Arhtrokinematics of the Pelvis Anteversion- Anterior pelvic tilt Retroversion- Posterior pelvic tilt Lateral tilt Rotation 22 Lumbopelvic rhythm: combined movements Combined & coordinated movements of:Hip-Pelvis-Lumbar spine to increase overall motion OKC Femur is moving (“ball in socket”): – Flex hip+PPT+lumbar flex – Ext hip+APT+lumbar ext CKC pelvis is moving (“socket in ball”): – APT+hip flex+lumbar ext – PPT+hip ext+lumbar flex 23 Combined Lumbopelvic Movements 24 Ostheokinematics of the hip Closed kinetic Chain (WB). Acetabulum moves on femur – Anterior-posterior pelvic tilt (APT:hip flexion PPT: hip extension) – Abduction-adduction (“hip hike”) – External-internal rotations (R pelvic rotation: R leg IR, L leg ER) 25  Arthrokinematics of the Pelvis Anteversion ANTERIOR TILT. Lateral Axis: lumbosacral and coxal-femur Descent ASIS. Ascent of PSIS SACRUM: COUNTERNUTATION Associated to movements of lumbar hypelordosis. Lumbar Extension Movement 26  Arthrokinematics of the Pelvis Retroversion POSTERIOR TILT. Plane AP Lateral Axis: lumbosacral and coxal-femur Ascent ASIS. Descent of PSIS SACRUM: NUTATION Associated to movements of lumbar kyphosis. Lumbar Flexion Movement 27 Osteokinematics of the Pelvis 28 Osteokinematics of the Pelvis 29  Osteokinematics of the Pelvis Lateral tilt Lateral movement. Frontal Plane AP Axis: between lumbosacral and coxal-femoral. Descent of ASIS from one side. Ascent of contralateral ASIS. Asssociated to movements of abduction and adduction. Associated to movements of contralateral displacement of the pelvis 30  Osteokinematics of the pelvis Lateral tilt 31  Osteokinematics of the Pelvis Rotation Rotational movement. Transversal Plane Superior –Inferior Axis ANT movement of ASIS of one side. POST movement of the contralateral ASIS. Associated to movements during gait When I stride, rotation to the opposite side, to the side I am stepping with. Lumbar Spine rotates on the opposite sense. 32A  Osteokinematics of the Pelvis Rotation of the Pelvis 33A  Kinetics and Stabilizers All the muscles in conjunction with the aforementioned ligaments stabilize the SI joint. Craniocaudal interactions are the ones that will give us movements in the 3 planes. 34  Which muscles will act in pelvic movements? Anteversion Caudal Iliopsoas Rectus Femoris Sartorius Hip Flexors- Anterior Chain 35  Which muscles will act in pelvic movements? Anteversion Craneal Erector Espinae Trunk Extensors Lumbar Extensors- Lumbar posterior chain. 36  Which muscles will act in pelvic movements? Retroversion Caudal Gluteus Maximus Hamstrings Piriformis 37  Which muscles will act in pelvic movements? Retroversion Craneal Rectus Abdominis External Oblique 38 Combined Lumbopelvic Movements 39  Reasoning questions During childbirth, reason why is lying supine is potentially the most difficult position for the baby to go through the pelvic outlet? In the gait cycle, what movements of the pelvis take place? APT/PPT, LT, Rotations… 40