Due to our increased sedentary lifestyle and increased time spent sitting our postures have been affected, most particularly affecting our our mid-thoracic region which has become more kyphotic.
The thoracic spine tends not to be a direct producer of pain due to it’s stability from the rib cage however there are functional and biomechanical deficits in the thoracic spine that have secondary consequences affecting our posture. An increased thoracic kyphosis may lead to a forward head posture, chin protrusion, round shoulders, increased lumbo-sacral lordosis and approximation of the sternum and symphysis.
Mid-Thoracic Dysfunction –
Increased kyphosis of the thoracic spine from T4 – T8 as a result of prolonged sitting in constrained postures can lead to changes in the thoracic, lumbo-pelvic and cervico-cranial posture. Due to an increased thoracic kyphosis biomechanical overload and functional adaptations can occur.
Brugger’s Sternosymphyseal Syndrome is a collection of pain syndromes, functional limitations and performance deficits as a result of postural disorders.
Increased mid-thoracic kyphosis pitches the shoulders forward into a rounded and internally rotated position causing the pectorals, internal rotators, subscapularis, pectorals, and latissmus dorsi to habituate to a shortened length. In addition there can be increased stress on the glenohumeral joint anteriorly and superiorly which can alter the scapulohumeral rhythm, reducing mobility in arm elevation and predisposing to mechanical impingement of the subacromial space, anterior labrum instability and rotator cuff tendonitis.
Relationship of Functional Adaptatioins to Areas of Biomechanical Overload:
Functional Adaptation –
- Round shoulders and upper trapezius over-activity
- Head forward posture
- Chin protrusion
- Sternal-symphyseal approximation
- Increased lumbar lordosis
Areas of Biomechanical Overload –
- Glenohumeral joint (impingement)
- Cervico-cranial junction (hyperextension)
- TMJ (decreased mouth opening)
- Diaphragm (faulty respiration)
- T/L erector spinae (hypertrophy)
When the shoulders are rolled forward the upper trapezius adapt by tensing this upper trapezius tension is usually mistaken and treated as a patient’s primary problem when it may be secondary to other biomechanical factors such as faulty posture. Other areas affected with mid thoracic dysfunction, include the lower cervical spine which tends to loses its normal lordosis and the cervico-cranial junction (C0-C1) begins to compensate by hyper-extending to keep the visual gaze in the horizontal plane. Thus treatments tends to be focused on the compensatory C0-C1 hyperextension overlooking the source of the functional adaptation.
With hyperextension of the cervical spine there tends to be chin protrusion which can alter the temperomandibular joint (TMJ). Chin protrusion tends to decrease the extensibility in mouth opening further altering the biomechanics of the TMJ and increasing stress on the disc. Also due to mid-thoracic dysfunction there tends to be changes in respiration secondary to sternosymphyseal syndrome which occurs due to lower rib compression on the diaphragm. The accessory muscles of respiration – scalenes and shoulder girdle elevators substitute for the inhibited diaphragm resulting in upper chest breathing over belly breathing – i.e. the chest rises vertically rather than widening of rib cage in the horizontal plane.
When thoracic kyphosis is increased compensations occur in an attempt to stabilize the body’s center of mass and restore equilibrium. As well in an attempt to compensate for the forward drawn posture there tends to be over-activity of the thoracolumbar erector spinae. This then may lead to an increased anterior pelvic tilt and shortened psoas or an increased lumbar lordosis may be present as a result of a secondary compensation or functional adaptation due to the decreased thoracic mobility in extension.
Myofascial Pain and Muscle Imbalance with Mid-Thoracic Dysfunction T4-T8 –
Postural change due to an increased kyphosis tends to cause muscle imbalances leading to change in joint positions of the agonist and antagonist muscles surrounding joints. Therefore a functional adaptation to thoracic kyphosis leads to other tissues becoming overloaded thus generating pain.
Shortened Muscles – Suboccipitals, Pectorals, Masseters and lateral pterygoids
Overactive Muscles – SCM, Upper trapezius, Scalenes
Inhibited Muscles – Deep neck flexors, Lower trapezius, Diaphragm, Digastrics
Treatment of mid-thoracic dysfunction should be directed at both pain generating tissues plus the functional-biomechanical deficits responsible for the overload. Treatment should involve mobilizations and strengthening of mid-thoracic extensor joints and muscles in addition – advice and manipulation (joints and soft tissue) and exercises should be prescribed. However perpetuating factors which can lead to recurrence and should be addressed for prevention and recurrence.
Liebenson, C. Self-treatment of Mid-Thoracic Dysfunction: A Key Link in the Body Axis Part I Overview and Assessment. Journal of Bodywork and Movement Therapies. 2001; 5 (2): 90-98.
Libenson, C. Self-treatment of Mid-Thoracic Dysfunction: A Key Link in the Body Axis Part II: Treatment. Journal of Bodywork and Movement Therapies. 2001; 5 (3): 191-195.