Dorsal dislocation of the ulnar styloid and extensor carpi ulnaris tendon into the distal radioulnar joint: the empty sulcus sign

Imaging Findings of the Distal Radio-Ulnar Joint in Trauma

Traumatic lesions of the distal radio-ulnar joint (DRUJ) occur frequently in conjunction with fractures of the distal radius. They are a common cause of pain and limited range of motion after distal radial fractures. Due to the complex anatomy they are however often ignored or underappreciated. Distal radial fractures and luxations of the DRUJ often disturb the normal curvature of the radial notch and cause damage to the cartilage of this joint. The growth of the radius may be disrupted, resulting in a positive ulnar variance, and possibly give rise to complications such as ulnar abutment and motion restriction.

Ulnar styloid fractures – sometimes barely visible on plain film – may give rise to symptomatic bony pseudarthrosis, dislocation and laceration of the tendon of the m. extensor carpi ulnaris and a rare posttraumatic deformity of the ulnar epiphysis. Also the possibility of lesions at the adjacent triangular fibrocartilage complex and the joint capsule should be kept in mind.

This paper presents a pictorial review of the complex functional anatomy and pathologic conditions of this joint and emphasises why the DRUJ should be evaluated independently and thoroughly. The merit of each imaging modality is mentioned.

A correction article relating to Fig. 2 and Fig. 27 can be found here: http://dx.doi.org/10.5334/jbr-btr.966

Clinical and non-clinical aspects of distal radioulnar joint instability

Untreated distal radioulnar joint (DRUJ) injuries can give rise to long lasting complaints. Although common, diagnosis and treatment of DRUJ injuries remains a challenge. The articulating anatomy of the distal radius and ulna, among others, enables an extensive range of forearm pronosupination movements. Stabilization of this joint is provided by both intrinsic and extrinsic stabilizers and the joint capsule. These structures transmit the load and prevent the DRUJ from luxation during movement. Several clinical tests have been suggested to determine static or dynamic DRUJ stability, but their predictive value is unclear. Radiologic evaluation of DRUJ instability begins with conventional radiographs in anterioposterior and true lateral view. If not conclusive, CT-scan seems to be the best additional modality to evaluate the osseous structures. MRI has proven to be more sensitive and specific for TFCC tears, potentially causing DRUJ instability. DRUJ instability may remain asymptomatic. Symptomatic DRUJ injuries treatment can be conservative or operative. Operative treatment should consist of restoration of osseous and ligamenteous anatomy. If not successful, salvage procedures can be performed to regain stability.

Management of soft-tissue injuries in distal radius fractures

Distal radius fractures account for approximately 15% of all fractures in adults, and are the most common fractures seen in the emergency department. Soft-tissue injuries associated with distal radius fractures may influence strategies for the acute management of the fracture, but also may be a source of persisting pain and/or disability despite fracture healing. This article describes soft-tissue injuries and considerations for treatment associated with distal radius fractures, including injuries to the skin, tendon and muscle, ligaments, the triangular fibrocartilage complex, neurovascular structures, and related conditions such as compartment syndrome and complex regional pain syndrome.

EXTENSOR CARPI ULNARIS SUBLUXATION OR DISLOCATION? ULTRASOUND MEASUREMENT OF TENDON EXCURSION AND NORMAL VALUES

Dislocation or subluxation of the extensor carpi ulnaris (ECU) tendon is one of the differential diagnoses of ulnar-sided wrist pain. No data exists on the degree of subluxation occurring in normal wrists. Retrospective review of surgical cases revealed two patients with dorsal and four with volar instability. Magnetic resonance imaging and ultrasound were not always predictive of the direction of instability. A standardised ultrasound technique was used to evaluate ECU subluxation in 20 asymptomatic wrists. In normal subjects, as a percentage of the width of the osseous groove, the volar edge of extensor carpi ulnaris may displace by up to 40% beyond the volar lip of the osseous groove with wrist flexion and the dorsal edge by 33% beyond the dorsal lip with wrist extension. The effect of gender on normal range and the diagnostic use of the standardised ultrasound technique need further evaluation.

Soft tissue complications of distal radius fractures

Distal radius fractures account for approximately 15% of all fractures in adults. Care of these fractures is associated with a myriad of complications. This review focuses on the soft tissue complications encountered during the management of distal radius fractures, including tendon injury, nerve dysfunction, vascular compromise, skin problems, compartment syndrome, complex regional pain syndrome, and ligament dysfunction. There are many vital soft tissue structures in close proximity to the osseous anatomy around the wrist, and the complications associated with the soft tissues may be more problematic than the bone injury itself.

Ultrasound imaging of normal displacement of the extensor carpi ulnaris tendon within the ulnar groove in 12 forearm-wrist positions

OBJECTIVE

Instability of the extensor carpi ulnaris (ECU) tendon can be a difficult clinical diagnosis because of normal changes in tendon position during wrist motion. Our goal was to determine the normal variation of ECU tendon displacement in 12 forearm-wrist positions.

SUBJECTS AND METHODS

Ultrasound imaging of the ECU tendons of 40 symptom-free wrists of healthy volunteers (13 women, seven men; mean age, 22.3 years; range, 20-25 years) was performed. Each ECU tendon was examined in 12 positions: four wrist positions (ulnar deviation, radial deviation, flexion, and extension) in each of three forearm positions (pronation, supination, and neutral).

RESULTS

ECU tendon displacement in the right hand was not significantly different from that in the left, and displacement in men did not differ significantly from that in women. There was a small but significant difference between displacement in the dominant and that in the nondominant hand (p < 0.02). Mean ECU tendon displacement was greatest in the supinated forearm position (p < 0.001) followed by the neutral position (p < 0.001) and was least in the pronated position (p < 0.001). Both ulnar deviation (p < 0.001) and flexion (p < 0.002) were associated with greater ECU tendon displacement than were radial deviation (p < 0.001) and extension (p < 0.002). Maximum percentage displacement volar to the ulnar border of the groove was 50% in flexed supination and ulnar deviation. The maximum displaced distance volar to the ulnar border of the groove was 5 mm.

CONCLUSION

Sonographic evaluation of the ECU tendon is simple and practical. Knowledge of normal ECU displacement relative to the ulnar groove may help in evaluation of ulnar-sided wrist pain.

Irreducible Galeazzi fracture-dislocation due to intra-articular fracture of the distal ulna

Irreducible Galeazzi fracture-dislocation is a rare injury. Structures that mechanically block the reduction are usually soft tissues. We present an irreducible case due to distal ulnar intra-articular fracture.

Galeazzi fractures in adults

Galeazzi fractures are not uncommon. They frequently result from falls with forced hyperpronation of the forearm. They are potentially unstable because of certain destabilizing factors at the wrist. Early recognition is essential, as is early operative xation of the radius in adults. This paper reviews the English language literature and current knowledge of Galeazzi fractures in adults.

Classification and treatment of ulnar styloid nonunion

Symptomatic nonunion of the ulnar styloid is an uncommon problem that is usually best treated by simple excision of the ulnar styloid fragment. Two types of nonunion of the ulnar styloid are described here on an anatomic basis, and their treatment differs. Type 1 is defined as a nonunion associated with a stable distal radioulnar joint. Type 2 is defined as a nonunion associated with subluxation of the distal radioulnar joint. The postoperative follow-up period for the two types ranged from 4 months to 13 years, with a mean of 5 years 2 months. Eleven type 1 wrists were treated with excision of the fragment, and all patients had satisfactory relief of pain. Nine type 2 wrists required restoration of the anatomy of the traingular fibrocartilage complex. Three of these had large fragments that were treated by open reduction and internal fixation. All three patients were completely relieved of their discomfort. Six other patients underwent excision of the fragment and repair of the triangular fibrocartilage complex to the distal ulna. This group had four excellent, one good, and one fair result. If the distal radioulnar joint is stable on presentation or if its stability is restored, then long-term relief of pain from ulnar styloid nonunion is achieved by treatment of the nonunion.

Effects of radioulnar instability on the radiocarpal joint: a biomechanical study

Five fresh cadaver upper extremities were studied with use of a static positioning frame, pressure-sensitive film and a microcomputer-based videodigitizing system to assess the effect of increasing radioulnar instability on the load distribution within the proximal carpal joint. Three stages of radioulnar instability were studied: (1) an avulsion fracture at the base of the ulna styloid; (2) an avulsion fracture at the base of the ulna styloid plus disruption of the dorsal portion of the distal radioulnar joint capsule; and (3) an avulsion fracture at the base of the ulna styloid, disruption of the dorsal portion of the distal radioulnar joint capsule, and disruption of the radioulnar interosseous membrane. All stages of radioulnar instability demonstrated a decrease in the lunate contact area in positions with the forearm in supination. In stage 3 instability there was also less lunate contact area in positions with the forearm in neutral pronation/supination. In stage 3 instability the lunate high pressure area centroid was abnormally palmar in all positions and the scaphoid high pressure area centroid was abnormally palmar in positions with the forearm in pronation or supination.