There is a distinct lack of specific literature related to mechanical thoracic pain and this is all of a poor quality. Non-specific or mechanical thoracic pain can be defined as pain, tension, soreness and/or stiffness in the mid back or thoracic region. It is evoked by noxious stimulation of structures in the thoracic spine (Bogduk, 2009).
The mid back or thoracic region extends from the prominence of the C7 spinous process to the bottom of the rib cage. Some individuals may also feel pain around their chest wall, or isolated patches of pain, but spinal pain usually predominates (Appendix 2).
Cause
In approximately 90% of patients with low back pain (LBP) no specific patho-anatomic cause can be found (CSAG, 1994). It is likely to be the same for the thoracic spine.
Several structures in the thoracic spine including the joints, discs, muscles, nerves, vascular and connective tissues may be responsible for the pain symptoms but it is often not possible to identify a specific cause (Bogduk, 2009). Other structural causes may also be relevant e.g. Scheuermann's disease, osteoporotic collapse, thoracolumbar or cervicothoracic scoliosis, ankylosing spondylitis, chronic pain.
Mechanical thoracic pain can often be mistaken for visceral-originating symptoms (Appendix 3) (McKenzie and May, 2006). Pain around the scapular region and upper thoracic spine may also be from cervical origin (Cloward, 1959) and therefore any combination of neck and scapular or shoulder pain is probably referred from the cervical spine (McKenzie and May, 2006).
Prevalence
It has been estimated that there is a 3% population prevalence for thoracic pain (Linton et al, 1998). In a population study of 35 – 45 year olds, 66% had reported spinal pain in the previous year. Of this, 15% was in the thoracic area, 56% reported LBP and 44% reported cervical pain (Linton et al, 1998). It has also been reported that patients with thoracic pain represent 2.6% of the musculoskeletal physiotherapy caseload within the UK (McKenzie and May, 2006).
Presentation
Pain presentation is usually in a local area but symptoms are variable within the thoracic spine with or without referred symptoms or isolated patches to anterior chest or trunk (Appendix 2)
- Upper thoracic refers around the scapulae and upper chest wall
- Mid thoracic refers below the scapulae and around chest wall
- Lower thoracic refers into lumbar and pelvic area below the ribs (McKenzie and May, 2006)
- Postural changes due to accommodation of the pain may be present
- Larger breast size
- Restricted and painful back movements
- Mechanical thoracic pain may be associated with kyphotic or scoliotic deformity