18.2.1 Ulnar Styloid Fractures/Nonunions

It is critical to evaluate the DRUJ for stability in these injuries as an unstable joint affects the outcomes. Fractures could be avulsion fractures which often do not influence the stability of the DRUJ or ulnar base fractures which are more likely to affect stability. If the radioulnar ligament is attached to the fragment then the joint will demonstrate instability. If fractures through the base of the ulnar styloid are displaced more than 2 mm, then operative intervention may be necessary whereas fractures through the tip are more likely to be stable. ¹ Radial translation of the fractured ulna indicates detachment of the radioulnar ligament which often causes instability of the DRUJ.

Indications for repair of nonunions include reattachment of the nonunited fragment if the fragment is large and instability is present. If the fragment is small, it may be excised and the radioulnar ligament may be reattached directly to the fovea. If pain is the main complaint and there is no concomitant instability, then the fragment may be removed with the assistance of wrist arthroscopy to evaluate the TFCC and ligamentous structures.

Fractures of the ulnar head involve the articular surface. They may be seen in isolation or may occur concomitantly with ulnar styloid fractures and ulnar shaft fractures. Distal ulnar neck/shaft fractures occur within 4 cm of the articular surface of the ulnar head. Often occurring with distal radius fractures, these fractures can be treated nonoperatively if reducible and stable after correction of the distal radius fracture, but may require stabilization due to instability.

Malunited distal radius fractures or distal ulna fractures may cause degeneration at the DRUJ. Indications for salvage procedures include pain with forearm rotation, swelling, decreased grip strength, stiffness, and failure of conservative treatment which includes injections and bracing. Salvage procedures are designed to eliminate the articulation between the distal ulna and radius by resecting the distal ulna, fusing the joint, or replacing the ulna.

Indications for distal ulna arthroplasty include highly comminuted fractures of the distal ulna that are not amenable to repair. Posttraumatic indications include symptomatic DRUJ arthritis. Arthroplasty should only be indicated after failure of conservative treatment such as physical therapy which includes a splinting program for at least 4 to 6 months before considering surgery for posttraumatic arthritis.

18.3.1 Approach

Most distal ulna pathology can be addressed through the same approach. The distal ulna is approached through a dorsal zig zag incision centered over the DRUJ. The dorsal sensory branches of the ulnar nerve should be identified and protected. The extensor retinaculum of the fifth compartment is identified and incised. Next, an ulnar based interval is developed between the extensor retinaculum and the separate dorsal sheet of the extensor carpi ulnaris (ECU) tendon without compromising the ECU tendon sheath. Next, the dorsal capsule is opened by creating a ulnar based flap raised from the 4–5 septum. The capsular incision begins at the neck of the ulna and is extend to the 4,5 intercompartmental artery. The incision is continued along the radiocarpal joint where it extends distally and ulnarly along the dorsal radiotriquetral ligament to the triquetrum while preserving the dorsal ligaments. The TFCC is identified next and the ulnar styloid, ulnocarpal joint, and ulnar neck can be visualized.

18.3.2 Ulnar Styloid Fractures Technique

There are multiple options to fix ulnar styloid base fractures which include conservative management in a supination brace, Kirschner wires (K-wires), tension band wiring, suture or screw fixation, and radial lengthening. Patients may be treated in a supination brace for 6 weeks if intraoperative assessment reveals instability when the forearm is in the neutral or pronated position but stability with forearm supination. The above arm supination brace is often customized by occupational therapy and is worn full time for 6 weeks. K-wires may be placed percutaneously or with a small incision to protect the dorsal sensory branch of the of the ulnar nerve. They are typically left outside of the skin and are removed after 6 weeks. Tension band fixation uses one or two oblique K-wires which are passed through the tip of the ulnar styloid. A 24-gauge stainless steel wire or suture is passed around the tip of the wire and through a drill hole in the ulnar neck in a figure of eight fashion. A suture anchor may be used in a similar fashion. The suture anchor is placed in the defect created by the ulnar styloid fracture and looped around the ulnar styloid or through the styloid if the fragment is large enough to pass a suture though without fragmenting the styloid. A subsequent drill hole is placed through the ulna proximally and the suture is passed through the hole and tied (▶Fig. 18.1).

The styloid may be also be secured with a headless compression screw. The styloid may be reduced percutaneously with a K-wire or a mini open incision may be made for protecting the dorsal ulnar sensory branch. The screw is then inserted over the K-wire stabilizing the fracture fragment (▶Fig. 18.2).

Radius lengthening is a newer technique for instability that involves a standard volar Henry approach with provisional fixation of the distal radius first distal to the fracture. The radius is then lengthened and fixed proximally distracting it and tightening the TFCC.