Rib Dysfunction Syndrome is an often overlooked condition that has identifiable signs and symptoms and usually responds to manipulative techniques. A review of the anatomy and proper function of the rib joint is essential to the understanding of this syndrome. The rib joint from the second to the tenth thoracic vertebra is a functional complex that is comprised of several distinct joints, the costotransverse and costovertebral joints posteriorly and the costosternal and costochondral joints anteriorly. The costotransverse joint describes the articulation between the rib tubercle and the transverse process of the thoracic vertebra while the costovertebral joint describes the articulation between the rib head and the vertebral body. The sternocostal joints describe the articulations between the anterior end of the rib and the sternum for ribs one through five while the costochondral joints describe articulations between the lower six to seven ribs and the lowermost aspect of the sternal articulation. These joints are anatomically distinct however since they originate on a single rib they function as a single unit and are therefore assessed clinically as such. These joints are diarthrodial (synovial) composed of a fibrous outer capsule that limits their excursion and surrounds articular cartilage that is lubricated by synovial fluid. The first, eleventh, and, twelfth thoracic vertebra articulate with the rib head solely. Not surprisingly Nathan et al. have described osteoarthritis changes occurring to the first, eleventh, and, twelfth ribs a disproportionate amount of time. The costovertebral articulations are paired which provides an easily assessable comparison when examining patient with suspected rib dysfunction. The costotransverse joint besides its joint capsule is strengthened by three costotransverse ligaments:

1. The interosseous costotransverse ligament is a short, stout structure spanning the distance between the transverse process and the posterior surface of the neck of the rib.

2.The posterior costotransverse ligament is a rectangular shaped structure approximately 1.0xl.5cm in area spanning the space between the tip of the transverse process and the lateral border of the costar tubercle.

3. The superior costotransverse ligament is a strong ,thick, flat structure that tethers the inferior border of the transverse process to the superior border of the adjacent rib below.

The costovertebral joint is divided into superior and inferior portions each with its own facet. This is due to the intervertebral location of the articulation. Its ligamentous support includes an interosseous ligament which joins the head of the rib to the intervertebral disc separating the two facets and a radiate ligamentous complex composed of three distinct bands superior, inferior, and intermediate.

The innervation of the joints unlike the nearby apophyseal joints; which receive their innervation from the dorsal ramus receive a branch from the ventral ramus of the spinal nerve. Despite these anatomically distinct innervations apophyseal joint dysfunctions are clinically similar to rib dysfunctions. Unfortunately the treatments are not interchangeable. Common symptoms include arm pain, pain in the back and between the ribs and generalized thoracic area discomfort. Additionally there is a close relationship between the somatic and the autonomic nervous systems in the thoracic area. This results in symptoms of the thoracic spine and thoracic wall being influenced by internal organs such as the heart, vessels and lungs. The literature is replete with case reports of patients admitted to coronary care units for presumed myocardial infarctions only to be treated for rib dysfunction syndrome. Many internists have discovered that primary pulmonary pathology can manifest clinically as vague thoracic area discomfort or pinpoint thoracic or chest wall pain. Greenman classifies rib dysfunctions as structural and respiratory.

Structural rib dysfunctions result from subluxations, torsions, or damage to the rib articulations. This effectively causes nonphysiologic motion patterns that stimulate the ventral ramus of the segmental nerve root producing localized discomfort. The respiratory apparatus necessitates constant movement of the ribs which results in near constant stimulus of the dysfunctional level. This in part explains why patients with rib dysfunctions may appear so disabled.

Anterior subluxations manifest clinically with tenderness when tension is applied to the iliocostalis muscle. The rib is less prominent in the posterior rib cage and more prominent in the anterior rib cage. Patients frequently complain of intercostal neuralgia at adjacent segments.

Posterior subluxations also result in tenderness when tension is exerted over the iliocostalis muscle however the dysfunctional rib is more prominent posteriorly and less prominent anteriorly.

Superior first rib subluxations clinically result in marked tenderness over the superior aspect of the first rib and hypertonicity of the ipsilateral scalene muscles. Palpation of the first rib in contrast to the contralateral side will be noted to be approximately 5mm higher.

External rib torsions are diagnosed by demonstrating that the superior border of the dysfunctional rib is more prominent and likewise the inferior border is less prominent. Again the iliocostalis muscle is tender when palpated at the rib angle.

Internal rib torsions have opposite findings as external torsions and are usually found on the contralateral side, of an external rib torsion. External rib torsional dysfunctions are more common than internal rib torsions.

Rib compression dysfunctions result from trauma to the thoracic cavity and although rare are easily diagnosed. The involved rib is flattened anteriorly and posteriorly resulting in prominence in the midaxillary line. The trauma required to produce such a distortion results in painful intercostal spaces above and below the involved rib.

Lateral flexed rib (bucketbail) dysfunctions also results in prominence of the rib in the midaxillary line however the interspaces above and below the involved rib are asymmetrical when palpated. Although this dysfunction may initially appear difficult to diagnose it fortunately has a tendency to occur in ribs two, three and, four and the rib is usually flexed upwards narrowing the interspace in the midaxillary line superiorly and widening the interspace in the midaxillary line inferiorly.

Respiratory rib dysfunctions occur either singly or in groups and are marked by restriction of either inhalation or exhalation movement. The importance of recognizing group respiratory rib dysfunctions lies in identifying the so called key rib. The key rib as its name indicates is the major restrictor of the group's ability to move into inhalation or exhalation. It is the inferior most rib of the dysfunctional group in exhalation rib dysfunctions or the superior most rib in inhalation rib dysfunctions. The key rib always leads the dysfunctional movement dragging successive ribs behind. It is identified by palpating the ribs and determining the inferior most rib that ceases to move first during forced exhalation and vice versa for inhalation. Multiple key ribs can occur in noncontiguous respiratory rib dysfunctions.