The innervation of the triangular fibrocartilage complex: Nitric acid maceration rediscovered

Injury to the triangular fibrocartilage complex (TFCC) is frequently implic ated in the etiology of ulnar-sided wrist pain. This study examines the ner vous anatomy of the TFCC using a nitric acid maceration technique and attem pts to correlate this information with known tear patterns. Ten fresh froze n cadaveric specimens were studied in detail. Cross dissection of each uppe r-extremity specimen included removal of all flexor and extensor tendons. A fter identification and labeling with permanent color of the ulnar nerve, d orsal sensory branch of the ulnar nerve, posterior interosseous nerve, ante rior interosseous nerve, and median nerve, an en bloc excision of the dista l radioulnar region was performed. Digestion of the soft tissue was perform ed with nitric acid at sequential concentrations of 50% and 33% for 9 of 10 specimens. The digestion was halted by immersing the specimen in a mixture of 10% formaldehyde and 1% glycerine. After removal of bone, the specimens were fixed in paraffin, sectioned, and stained with hematoxylin and eosin. Nine of the 10 specimens were studied microscopically to determine the con tribution of the grossly identified ner? es to each zone of the triangular fibrocartilage complex as defined by Palmer's classification of acute TFCC tears. The anterior interosseous, median, and superficial radial nerves did not contribute to the innervation of the TFCC. The intraarticular course o f the peripheral nerves could not be defined in the one specimen that was n ot digested with nitric acid. Nitric acid maceration is a rediscovered tech nique for identifying the nervous anatomy of soft tissues. The study showed that the triangular fibrocartilage complex is innervated by branches of th e posterior interosseous, ulnar, and dorsal sensory ulnar nerves in a fairl y consistent manner. Implored treatment of TFCC tears may result from an en hanced understanding of the supporting structures' innervation and mechanic al function.