Posture & Mechanics
 

Pelvic Instability Network Support (PINS)
 
Changing Posture & Pelvic Instability back
The body's posture changes as the pregnancy progresses. The pelvis tilts and the back arches to help keep balance. Poor posture occurs naturally from your abdominal muscles becoming stretched as the baby grows. These muscles are less able to contract and keep your lower back in proper alignment. Try to avoid upper body twists, squatting and heavy lifting. Avoid any activity that might put more strain on your pelvis especially for those suffering from pelvic girdle pain.
 
Changes in Posture with PGP back
  • Difficulty finding a comfortable posture for your back.
  • Unable to stand without bending the knees.
  • Having trouble standing and putting your weight forward.
  • Supporting yourself by other means.
  • The back leans forward.
  • The hips and knees, feet and ankles rotate and turn slightly.
  • The feet point more towards each other.

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    Common Mobility Changes with Pelvic Girdle Pain back
    It is common to have mobility issues associated with pelvic girdle pain. Below is a list of some of these changes.
  • Struggle or be unable to lift the foot off the ground.  
  • Struggle to walk up or down stairs.  
  • Struggle to walk up or down a slope.  
  • Struggle to walk on uneven surfaces.
  • Struggle to lift the leg.
  • You may also shuffle your feet and walk with a limp.
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    To Compensate the Posture Could Change as Follows  back
  • The back leans forward.
  • The hips rotate.
  • The legs bend at the knees more.
  • The knees turn slightly.
  • The feet point more towards each other.
  • The position and angle of the ankle changes.
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    Unstable Pelvis and Walking (another term for walking is gait) back
    Abnormality of gait is usually a consequence of pain, weakness, a difference in the lengths of the limbs or an unsuccessful ability to transfer weight through the pelvic joints.  Normal gait tends to minimize displacement of centre of gravity through actions such as pelvic rotation and pelvic tilt.
     
    As you walk the pelvic the pelvis goes through these 4 motions. back
       1. Anterior tilt: pelvis moves anteriorly and inferiorly.
       2. Posterior tilt: pelvis moves posteriorly and superiorly.
       3. Lateral tilt to the left/right: one iliac wing is higher than the other.
       4. Rotation to the left/right: one iliac wing anterior to the other.
     
    Unstable Pelvis and Walking During Pregnancy back
    During pregnancy there may be an increased demand placed on hip abductor, hip extensor, and ankle plantar flexor muscles during walking. During the motion of walking, an upward movement of the pelvis, one side then the other, is required to let the leg follow through. The faster or longer each step the pelvis adjusts accordingly. The flexibility within the knees, ankles and hips are stabilized by the pelvis. A strong network of the connecting ligaments and muscles limit movement in the pelvic joints. The pelvic joints cannot function properly without the support of the ligaments and muscles. Both are needed to maintain normal function.
     
    Normal gait tends to minimize displacement of centre of gravity whereas abnormal gait through pelvic instability tends to amplify displacement. To avoid pain on weight-bearing structures a very short stance phase and limp occurs on the injured side(s), this is called "Antalgic Gait".
     
    Length of Step & Pelvic Instability back 
    The pregnant woman has a different pattern of gait. The step lengthens as the pregnancy progresses. This is due weight gain and changes in posture. Both the length and height of the footstep shortens with pelvic girdle pain. Sometimes the foot can turn inwards due to the rotation of the hips when the pelvic joints are unstable. On average, a woman's foot can grow by a half size or more during pregnancy. Pregnancy hormones that are released to adapt the bodily changes also affect the ligaments in the foot. In addition, the increased body weight of pregnancy, fluid retention and weight gain lowers the arches, further adding to the foot's length and width. There is an increase of load on the lateral side of the foot and the hind foot. These changes may be responsible for the musculoskeletal complaints of lower limb pain in pregnant women.  
     
     

    		 
     

    Footsteps representing normal and unstable pelvis and gait 

    		 
     
    Motions & Functions of the Symphysis Pubis back
    Analysis of the pelvis shows that the boney regions function as arches, transferring the weight of the up-right trunk from the sacrum to the hips. The symphysis pubis connects these two weight-bearing arches and the ligaments that surround this pelvic region maintain the mechanical integrity.
     
    The Main Motions of the Symphysis Pubis are:
  • Superior/ inferior glide.
  • Separation/ compression.
    • The Functions of the Joint are to:
  • Absorb shock absorption during walking.
  • Delivery of baby.
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    Problems Resulting from Pelvic Malalignment back
    When a pelvis is out of alignment, the spine is out of alignment. When the spine is out of alignment, there are adverse effects on the neurological system. For example - nerves entering and exiting the spine may be compressed and thus unable to perform their function to the full extent. Circulation and metabolism will be affected, and digestion and elimination can suffer. Legs will be thrown out of alignment, potentially causing knee and ankle problems. More weight will be placed on one hip than the other, causing more 'wear and tear'.
     
    Types of Malalignment back
    1.Rotational malalignment of the pelvis - resulting from excessive anterior or posterior rotation of an innominate bone (pelvic bone) relative to the sacrum and upslip of the sacroiliac joint .
    2. Vertebral mal-rotation - malalignment of the pelvis because of rotation or upslip, and sacral torsion can occur in isolation or in various combinations with each other.
    3. Rotation of vertebrae - anywhere along the spine can cause malalignment of the pelvis or vice versa. In the lumbosacral region, for example, this may be because of the direct connections between the lower vertebrae and the pelvis by way of the disc, facet joints and ligaments.
    4. Rotation of the upper vertebrae of the spinal column, namely C1 and C2, can also cause pelvic malalignment and vice versa.
     
     

    		 
     

    Anterior & vertical displacement | Normal load transfer in pelvis

    		  
     
    Muscles Used for Pelvic Movement back
    Muscles for Pelvic Anterior Tilt
    Hip flexors, iliopsoas, rectus femoris, lumbar extensors, erector spinae.
    Muscles for Pelvic Posterior Tilt
    Abdominal muscles, rectus abdominis, hip extensors, hamstrings, gluteus maximus.
    Muscles for Pelvic Rotation
    For right rotation:  Left lumbar rotators, left hip external rotators, right hip internal rotators.
    For left rotation: Right lumbar rotators, right hip external rotators,  left hip internal rotators.
    Muscles for Pelvic Lateral Tilt
    For lateral tilt to the right:  Left quadratus lumborum, right hip abductors muscles.
    For lateral tilt to the left right: Quadratus lumborum, left hip abductors.
     
     
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