1. Ideal alignment:
The following is an overview of ideal alignment:[4]
Head and neck the ideal position for the head and neck is one in which the head is well balanced and supported with a minimal amount of muscular effort. From the side view plumb line, the line should intersect through the ear canal and there should be a slight anterior curvature to the cervical spine. The head position should not be too far anterior or turned up or down.
Upper back alignment of the upper back is maintained by the lumbar spine and the pelvis and should have a minimal curve in the posterior direction. If there is excessive lordosis of the lumbar spine, the thoracic spine compensates and takes on a more flat back appearance straightening out the thoracic spine.
Chest the chest position should be up and slightly forward. This is somewhere between full inspiration and forced expiration.
Abdomen In adults the abdomen should be flat, however in children younger than 10 years old it is normal for the abdomen to protrude slightly.
Shoulders and arms In a neutral posture the scapulas should lie flat on the back between the 2nd and 7th thoracic vertebrae and the scapulas should sit approximately 4 inches apart. When examining from the side view plumb line, the line should intersect the middle of the shoulder joint, or glenohumeral joint. The arms should lie beside the trunk with a slight bend in the elbow and palms facing the body.
Pelvis and low back a neutral pelvis occurs when there is balance between each anterior superior iliac spine, which is the bony projections on the front of the hips. These two bony projections should be in the same horizontal plane and be pointing forward. When there is a neutral pelvis there is a natural lordotic curve and neutral lumbar spine. When looking at the side view plumb line, the line should intersect the centre of the acetabulum (hip socket). Using solely the side view does not give sufficient information about the position of the pelvis as it can shift side to side. Therefore it is important to note the level of the anterior superior iliac spine in a horizontal plane as well.
Hips and Knees When evaluating these joints from the side view the line should pass slightly posterior to the centre of the hip joint and slightly anterior to the centre of the patella. There should be even weight distribution between left and right side and knee caps should point anteriorly.
Ankles in side view, the plumb line should intersect slightly anterior to the lateral malleolus, the large bone at the side of the ankle. In a neutral position when the knee is straight, the ankle is held at 10 degrees of dorsiflexion (decreasing the angle between the top of the foot and the shin). This angle is greatly decreased when heel height is altered through footwear.
Feet and toes In a neutral position the feet should be separated approximately 3 inches and the feet turning outward about 8 degrees from each other and toes straight.