Ultrasound-Guided Injection Technique for Xiphisternal Joint Pain
The xiphisternal joint is susceptible to injury from acute blunt trauma from motor vehicle accidents and contact sports such as football and rugby as well as repetitive microtrauma from chronic coughing and activities that require repeated stooping. Left untreated, the acute inflammation associated with the injury may result in arthritis with its associated pain and functional disability.
Patients suffering from xiphisternal joint dysfunction or inflammation will complain of a pain when overeating, stooping, bending inspiring deeply, or coughing. A clicking sensation with joint movement is often noted, and the patient frequently is unable to sleep on the abdomen or side. Patients with xiphisternal joint dysfunction and inflammation will exhibit pain with any movement of the xiphisternal joint. Palpation of the xiphisternal joint often reveals swelling or enlargement of the joint secondary to joint inflammation. If there is disruption of the supporting ligaments of the joint, it may sublux or dislocate and joint instability and a cosmetic defect may be evident on physical examination (Fig. 85.1).
Plain radiographs are indicated in patients suffering from xiphisternal joint pain. They may reveal psoriatic arthritis, ankylosing spondylitis, Reiter syndrome, or widening of the joint consistent with joint injury (Fig. 85.2). They may also reveal occult fractures or primary or metastatic tumors of the joint as the joint is susceptible to invasion by tumors of the mediastinum including thymoma. If joint instability, infection, or tumor is suspected or detected on physical examination, magnetic resonance imaging, computerized tomography, and/or ultrasound scanning is a reasonable next step (Fig. 85.3). Ultrasound-guided xiphisternal joint injection can aid the clinician in both the diagnosis and treatment of xiphisternal joint pain and dysfunction.
CLINICALLY RELEVANT ANATOMY
The xiphisternal joint is the fibrocartilaginous articulation at the apex of the infrasternal angle between the body of the sternum and the xiphoid (Fig. 85.4). The joint lies at the level of the T9 vertebral body and is easily identifiable by palpation. The joint lies at the level of the second costal cartilage. Posterior to the xiphisternal joint are the structures of the mediastinum including the heart. These structures are susceptible to needle-induced trauma if the needle is placed too deeply. The xiphisternal joint allows protraction and retraction of the thorax. Above, the manubrium articulates with the sternal end of the clavicle and the cartilage of the first rib. Below, the body of the sternum articulates with the xiphoid process. Posterior to the xiphisternal joint are the structures of the mediastinum including the arch of the aorta. The xiphisternal joint is strengthened by ligaments but can be subluxed or dislocated by blunt trauma to the anterior chest. The xiphisternal joint is innervated by the T4-T7 intercostal nerves as well as by the phrenic nerve. It is thought that this innervation by the phrenic nerve is responsible for the referred pain associated with xiphodynia syndrome.