Intra-Articular Distal Ulnar Sliding Osteotomy for Ulnar Shortening.

Background: Ulnocarpal impaction is the most common reason to perform ulnar shortening osteotomy. There are 3 osteotomy techniques for ulnar shortening: transverse, step-cut, and oblique cut.First described by Milch in 1941, extra-articular diaphyseal oblique or transverse shortening is the most frequently performed type of shortening. However, it is associated with a nonunion rate of up to 10%, and irritation by implants requiring removal occurs in up to 28% of cases. Intra-articular procedures such as the wafer procedure affect the distal ulnar joint surface, which can lead to stiffness of the distal radioulnar joint (DRUJ) due to scar tissue formation and adhesion of the triangular fibrocartilage complex (TFCC). Lapner et al. described increased pressure in the DRUJ after the wafer procedure, which may lead to an early onset of osteoarthritis. Complication rates between 8% for open wafer procedures and 21% for arthroscopic wafer procedures have been described.Intra-articular shortening has also been described by Slade and Gillon in 2007 and Hammert et al. in 2012 and was tested in cadavers by Greenberg et al. in 2013. This closing wedge technique preserves the distal joint surface of the ulna and also allows for easy correction of the inclination of the hub joint surface of the ulna.In contrast to the technique of Slade, our described osteotomy is steeper and longer proximally, which allows for fixation with >2 screws. Rapid healing of the metaphyseal bone compared with diaphyseal bone is described, and implant removal is necessary less often.With the described procedure, the interosseous membrane remains untouched, especially the distal oblique bundle, which additionally provides stability of the DRUJ in 40% of patients.

Description: A dorso-ulnar approach through the fifth extensor sheath is performed. The ulnocarpal joint and the DRUJ are accessed through an arthrotomy distal and proximal to the TFCC. The foveal attachment of the TFCC and the subsheath of the sixth extensor sheath are visualized. The osteotomy is intra-articular oblique from distal ulnar to proximal radial. Sliding the head of the ulna proximally achieves the desired shortening of up to 5 mm, and the head is fixed using 2, 3, or 4 cannulated headless screws. A slight correction of the axis of the ulnar head is also possible.

Alternatives: An alternative to this procedure is extra-articular osteotomy using a palmar or dorsal ulnar approach. If necessary, additional ulnocarpal procedures can be performed in an open or arthroscopically assisted manner.

Rationale: The shortening takes place only in the articular part of the distal aspect of the ulna. This procedure can easily be combined with TFCC repair, synovectomy of the DRUJ, or repair or reconstruction of the lunotriquetral ligament if needed. Shortening of up to 5 mm is possible.