Non-structural misalignments of body posture in the sagittal plane

Abstract

Background: The physiological sagittal spinal curvature represents a typical feature of good body posture in the sagittal plane. The cervical and the lumbar spine are curved anteriorly (lordosis), while the thoracic segment is curved posteriorly (kyphosis). The pelvis is inclined anteriorly, and the lower limbs' joints remain in a neutral position. However, there are many deviations from the optimal body alignment.The aim of this paper is to present the most common types of non-structural misalignments of the body posture in the sagittal plane.

Main body of the abstract: The most common types of non-structural misalignments of body posture in the sagittal plane are as follows: (1) lordotic, (2) kyphotic, (3) flat-back, and (4) sway-back postures. Each one may influence both the skeletal and the muscular system leading to the functional disturbance and an increased strain of the supporting structures. Usually, the disturbances localized within the muscles are analyzed in respect to their shortening or lengthening. However, according to suggestions presented in the literature, when the muscles responsible for maintaining good body posture (the so-called stabilizers) are not being stimulated to resist against gravity for an extended period of time, e.g., during prolonged sitting, their stabilizing function is disturbed by the hypoactivity reaction resulting in muscular weakness. The deficit of the locomotor system stability triggers a compensatory mechanism-the stabilizing function is overtaken by the so-called mobilizing muscles. However, as a side effect, such compensation leads to the increased activity of mobilizers (hyperactivity) and decreased flexibility, which may finally lead to the pathological chain of reaction within the musculoskeletal system.

Conclusions: There exist four principal types of non-structural body posture misalignments in the sagittal plane: lordotic posture, kyphotic posture, flat-back posture, and sway-back posture. Each of them can disturb the physiological loading of the musculoskeletal system in a specific way, which may lead to a functional disorder.When planning postural corrective exercises, not only the analysis of muscles in respect to their shortening and lengthening but also their hypoactivity and hyperactivity should be considered.

Keywords: Body posture; Corrective exercises; Faults of body posture; Flat-back posture; Kyphotic posture; Lordotic posture; Sway-back posture.

Fig. 1

Good body posture in a 8-year-old boy—the head line (a) and the base line (b) overlaps each other (c). Note: AM—external auditory meatus; A—acromion; GT—greater trochanter; HF—head of fibula; LM—lateral malleolus

Fig. 2

A 12-year-old boy with non-structural sagittal misalignment of body posture: postural thoracic hyperkyphosis. a Front view. b Back view. c Side view. d Forward bend view

Fig. 3

A 14-year-old boy with structural sagittal misalignment of body posture: structural thoracic hyperkyphosis. a Front view. b Back view. c Side view. d Forward bend view

Fig. 4

A 12-year-old boy with thoracic hyperkyphosis developing in habitual standing position. a Habitual standing position, lateral view. b Prone habitual lying position reveals thoracic hyperkyphosis. c Active trunk extension causes correction—flattening of thoracic hyperkyphosis

Fig. 5

A 14-year-old boy with structural thoracic hyperkyphosis. a Habitual standing position, lateral view. b Lying prone position reveals maintaining thoracic hyperkyphosis. c Active trunk extension does not decrease the thoracic hyperkyphosis

Fig. 6

Lordotic posture in a 9-year-old girl. a Habitual standing, lateral view, note the hyperextension of the knees and plantar flexion of the feet. b Corresponding schematic representation of the shortened (red) and lengthened (blue) skeletal muscles. Note: AM—external auditory meatus; A—acromion; GT—greater trochanter; HF—head of fibula; LM—lateral malleolus

Fig. 7

Kyphotic posture in a 13-year-old boy. a Habitual standing, lateral view. b Corresponding schematic representation of the shortened (red) and lengthened (blue) skeletal muscles. Note: AM—external auditory meatus; A—acromion; GT—greater trochanter; HF—head of fibula; LM—lateral malleolus

Fig. 8

Kyphotic-lordotic posture in a 12-year-old boy. a Habitual standing, lateral view. b Corresponding schematic representation of the shortened (red) and lengthened (blue) skeletal muscles. Note: AM—external auditory meatus; A—acromion; GT—greater trochanter; HF—head of fibula; LM—lateral malleolus

Fig. 9

Flat-back posture in a 9-year-old boy. a Habitual standing, lateral view. b corresponding schematic representation of the shortened (red) and lengthened (blue) skeletal muscles. Note: AM—external auditory meatus; A—acromion; GT—greater trochanter; HF—head of fibula; LM—lateral malleolus

Fig. 10

Sway-back posture in a 11-year-old boy. a Habitual standing, lateral view. b Corresponding schematic representation of the shortened (red) and lengthened (blue) skeletal muscles. Note: AM—external auditory meatus; A—acromion; GT – greater Trochanter; HF—head of fibula; LM—lateral malleolus

Fig. 11

The angle between chest and a head indicates improper head position - protraction. Note: AM—external auditory meatus; A—acromion; GT—greater trochanter; HF—head of fibula; LM—lateral malleolus

Fig. 12

A 10-year-old boy presenting a lordotic posture. Note the following elements: increased lumbar lordosis, increased anterior pelvic tilt

Fig. 13

The maximal active knee extension keeping the hip flexed 90°—decreased flexibility of left hamstrings

Fig. 14

Trunk forward bend test—decreased flexibility of hamstrings and trunk

Fig. 15

Normal trunk flexion in sitting position with knees flexed