Ultrasound-guided injection technique for slipping rib syndrome is utilized to help diagnose and treat this uncommon cause of anterior chest wall and upper abdominal pain. Slipping rib syndrome, which is also known as rib tip syndrome, is a painful condition due to hypermobility of the anterior portion of the lower costal cartilages. Most often involving the 10th rib, and sometimes the 8th and 9th ribs, slipping rib syndrome is almost always the result of trauma to the anterior costal cartilages. Patients suffering from slipping rib syndrome complain of sharp, knife-like pain with any movement of the lower anterior cartilages. The patient may also note a clicking, snapping, or catching sensation with movement of the anterior costal cartilages or with deep inspiration.

On physical exam, the patient suffering from slipping rib syndrome will often exhibit splinting of the affected cartilages by forward flexing the thoracolumbar spine. Palpation of the affected anterior costal cartilages will cause pain as will the hooking maneuver test (Fig. 95.1). The hooking maneuver test is performed by having the patient lie in the supine position with the abdominal muscles relaxed while the clinician hooks his or her fingers under the lower rib cage and pulls gently outward. Pain and a clicking or snapping sensation of the affected ribs and cartilage indicate a positive test. Patients suffering from slipping rib syndrome will also exhibit a positive ultrasound slipping rib test on transverse ultrasound imaging of the affected rib. The ultrasound slipping rib test is performed by imaging the rib and associated anterior costal cartilage suspected of slipping with the patient’s abdominal wall completely relaxed and then having the patient perform a vigorous Valsalva maneuver. The test is positive if the affected rib moves cranially and overlaps the rib above it (Fig. 95.2A-F). If the anterior costal cartilage and adjacent ribs are intact, under ultrasound imaging, with vigorous Valsalva maneuver, the adjacent ribs will be seen to move in concert downward (Fig. 95.3A-F).

Plain radiographs are indicated for all patients who present with pain thought to be emanating from the lower costal cartilage and ribs to rule out occult bony pathology, including rib fracture and tumor. Based on the patient’s clinical presentation, additional testing may be indicated, including complete blood cell count, prostate-specific antigen, sedimentation rate, and antinuclear antibody testing. Computerized tomographic, magnetic resonance, or ultrasound imaging of the affected ribs and cartilage is indicated to help confirm the diagnosis of slipping rib syndrome and to help identify occult mass and/or lower intrathoracic or upper intra-abdominal or tumor (see Figs. 95.2 and 95.4).

The cartilage of the true ribs articulates with the sternum via the costosternal joints (Fig. 95.5). The cartilage of the first rib articulates directly with the manubrium of the sternum and is a synarthrodial joint that allows a limited gliding movement. The cartilage of the 2nd through 6th ribs articulates with the body of the sternum via true arthrodial joints. These joints are surrounded by a thin articular capsule. The costosternal joints are strengthened by ligaments. The 8th, 9th, and 10th ribs attach to the costal cartilage of the rib directly above. The cartilages of the 11th and 12th ribs are called floating ribs because they end in the abdominal musculature (see Fig. 95.5). Anatomic variations of the costal cartilage such as false ribs may predispose to the development of slipping rib syndrome (Fig. 95.6). The pleural space and peritoneal cavity may be entered when performing the following injection technique, and if the needle is placed too deeply and laterally, pneumothorax or damage to the abdominal viscera may result.

Ultrasound-guided injection technique for slipping rib syndrome can be carried out by placing the patient in the supine position with the patient’s arms resting comfortably at the patient’s side (Fig. 95.7). A total of 5 mL of local anesthetic is drawn up in a 10-mL sterile syringe. If the painful condition being treated is thought to have an inflammatory component, 40 to 80 mg of depot steroid is added to the local anesthetic. The anterior costal cartilage and associated ribs at the level to be blocked are then identified by palpation (Fig. 95.8). A linear high-frequency ultrasound transducer is
then placed in the transverse plane with the superior aspect of the ultrasound transducer rotated ˜15 degrees laterally over the affected costal cartilage and rib, and an ultrasound survey scan is obtained (Figs. 95.9 and 95.10). The rib will be identified as a slightly hyperechoic ovoid structure with a hypoechoic center. The rectus muscle will be seen just caudad to the ribs. The affected costal cartilages and associated ribs are then identified by the ultrasound slipping rib test (see Figs. 95.2 and 95.3).