In addition to the costovertebral and sternocostal joints, the three-dimensional structural integrity of the central chest wall is usually enhanced with additional connections between the anterior fifth through eighth ribs. These secondary costochondral joints, or bridging cartilages, are formed by an inferior projection of one rib that connects firmly to a superior projection of the rib below it with a thin layer of ligamentous tissue. The ligament can be stretched or disrupted through processes like trauma, skeletal hypermobility disorders, pregnancy, or degenerative change.
When disrupted, the anterior ribs can sublux on each other and irritate the intervening intercostal nerve directly posterior to the joint. This process most commonly occurs at the joint between the fifth and sixth ribs. The resulting pain is commonly felt in the infrapectoral region at the inframammary fold and typically radiates posterolaterally in a dermatomal distribution through the upper axilla and deep to the scapula. The pain can be debilitating and is often confused with pain of cardiac origin. Over time, the damaged joint calcifies in an attempt to heal, which further exacerbates the pain due to bone-on-bone grinding. Focal calcification and separation or fracture of the joint can be discerned on computed tomogram.
Successful temporary pain relief can often be accomplished with ablation of the intervening intercostal nerve. Permanent pain relief, in appropriate cases, can be secured with surgical excision of the damaged bridging cartilage. When considering excision, a surgeon must be aware of the potential chest wall instability it could create. Once excised, the involved anterior ribs and those inferior to them will rely solely on the stability of their sternocostal joints. There is significant variability among patients in the location and strength of each of the fifth through seventh sternocostal joints. Excision is contraindicated if there are inadequate sternocostal joints inferior to the level of the bridging cartilage under consideration for excision.
The Surgery
To begin, single-lumen endotracheal intubation was accomplished, and the patient was positioned supine with a slight elevation of the operative side. Nerve blocks were placed, and the anatomy was marked out and correlated with anatomy on imaging. The bridging cartilage was palpable as a lump within the intercostal space.
Next, a 3–4 cm incision was centered over the bridging cartilage within the inframammary fold if possible. After subcutaneous tissues had been divided, the external oblique fascia and muscle layers were each divided along the course of their fibers. The lateral border of the rectus abdominis muscle was elevated and retracted medially. The periosteum was then cleared from a 2 cm area of the two ribs comprising the bridging cartilage to expose the ligament and fractured osteophyte within the intercostal space. Anatomy may not be immediately clear, so palpation helps to identify structures.
A small rongeur forceps was then used to debride the entire bridging cartilage, leaving flat surfaces at the superior and inferior edges of the upper and lower ribs, respectively. Care was taken to avoid damage to the intercostal neurovascular bundle running along the posteroinferior border of the upper rib. The endothoracic fascia was kept intact to avoid pneumothorax and a 4 mm resulting gap between the involved ribs was deemed adequate to prevent nerve compression. The individual tissue layers were then closed to complete the operation.
References
- Sollender GE, White TW, Pieracci FM. Fracture of the Costal Cartilage: Presentation, Diagnosis, and Management. Ann Thorac Surg. 2019 Apr;107(4):e267-e268. doi: 10.1016/j.athoracsur.2018.08.076. Epub 2018 Oct 22. PMID: 30359588.
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