This video demonstrates hemiresection and interposition of the distal ulna as described by William Bowers in 1985. Bowers recommended this procedure for the management of rheumatoid, posttraumatic, or degenerative arthritis of the distal radioulnar joint, with the goal of preserving the ulnocarpal ligamentous complex and the triangular fibrocartilage complex. Bowers thought that the preservation of these structures would improve stability between the distal radius and the ulna and help mitigate ulnar translation of the carpus. Hemiresection and interposition of the distal ulna can be performed via two approaches. If the procedure is performed in combination with additional procedures, such as wrist arthrodesis or tenosynovectomy, a dorsal, longitudinal incision is centered over the base of the third metacarpal and extended proximally, ulnar to the Lister tubercle. If the procedure is performed independently, an oblique or chevron incision is made over the fifth dorsal compartment. If a chevron incision is used, the distal limb of the incision should be made parallel to the course of the dorsal sensory branch of the ulnar nerve to decrease the risk of ulnar nerve injury. After division of the extensor retinaculum, sufficient proximal and distal exposure is ensured to permit mobilization of the tendons within the fourth and fifth compartments. Access to the distal radioulnar joint is achieved by incising the capsule at the base of the fifth compartment. This should be extended carefully to prevent injury to the triangular fibrocartilage complex and proximally enough to permit adequate exposure of the distal ulna. After hemiresection of the ulnar head, radiographs should be obtained to confirm adequate removal of bone and articular surface. An anchovy may be placed between the radius and the remaining ulna. The palmaris longus or a tendon allograft may be used and should be secured to the volar capsular tissues with the use of a nonabsorbable suture. Alternatively, Bain described developing an ulnar-based flap that includes the dorsal retinaculum and capsule. Bain used these structures as interposition material by advancing and suturing them to the volar capsule, as we have performed in this video.