PATIENT EVALUATION

Diagnostic Imaging

Standard posteroanterior, oblique, and lateral radiographs are obtained when the patient sustains a displaced intra-articular fracture of the distal radius. Radiographs of the patient’s forearm should be included to assess additional injuries proximal to the radius that may involve the operative joint.

Displaced intra-articular fractures of the distal radius are a unique subset of distal radius fractures. These fractures are traditionally unstable and not amenable to traditional methods of closed manipulation and casting. It is important when evaluating a radiograph of a distal radius fracture to understand fracture patterns that may be unstable and require internal fixation. Lafontaine describes several radiographic features that signify unstable fractures of the distal radius.¹ They include dorsal comminution with more than 20 degrees of dorsal tilt, extensive dorsal comminution, an associated ulnar styloid fracture, and significant intra-articular involvement in patients older than 60 years. Additional radiographic parameters include extensive dorsal comminution volar to the midaxle line of the distal radius and initial shortening greater than 4 mm of the distal radius compared with the ulna.

Displaced intra-articular fractures of the distal radius that involve the distal radioulnar joint significantly affect the final prognosis. It is important to reconstruct the bony anatomy of the lesser sigmoid notch of the distal radius to decrease the patient’s symptoms with pronation and supination of the forearm. Evaluation with computed tomography (CT) may help to identify any fracture lines that involve the distal radioulnar joint and may be helpful in surgical planning.

Arthroscopic management can further delineate these fracture lines and any associated soft tissue injuries that may involve the distal radioulnar joint and particularly the pathology of the triangular fibrocartilage complex.

Assessment of Associated Soft Tissue Injuries

Several studies have found a high incidence of intra-articular soft tissue injuries associated with displaced intra-articular fractures of the distal radius. Mohanti and Kar ² and Fontes and colleagues,³ in two separate wrist arthrography studies, identified a high incidence of injury to the triangular fibrocartilage complex associated with fractures of the distal radius.²^,³ Mohanti and Kar reported a 45% incidence of tears to the triangular fibrocartilage complex in 60 patients.² In a similar study, Fontes and coworkers found a 66% incidence of tears of the triangular fibrocartilage complex among 58 patients.³

Other arthroscopic studies have demonstrated a high incidence of injury to the triangular fibrocartilage complex. Geissler and colleagues reported their experience with 60 patients with displaced intra-articular fractures of the distal radius.⁴ In the series, 49% of the patients had a tear of the triangular fibrocartilage complex, most of which were peripheral and reparable. Injury to the scapholunate interosseous ligament was identified in 32%, and tears of the lunotriquetral interosseous ligament were reported in 15% of the patients.⁴ Landau and coworkers, in a similar arthroscopic study of 50 patients, found tears of the triangular fibrocartilage complex were the most common type and occurred in 78% of patients.⁵ Tears of the scapholunate interosseous ligament were identified in 54%, and tears of the lunotriquetral interosseous ligament were found in only 16% of the patients. In an arthroscopic study, Hanker reported that tears of the triangular fibrocartilage complex were present in 55% of the 65 patients in his series.⁶ Common in all three studies were injuries of the triangular fibrocartilage complex in which ulnar-sided pathology was most commonly associated with displaced intra-articular fractures of the distal radius.

Geissler and associates described an arthroscopic classification of interosseus ligament injuries based on their experience with the arthroscopic management of intra-articular distal radius fractures.⁴ They observed that a spectrum of interosseous ligament injury occurred. The interosseous ligament stretches and attenuates, and it eventually tears from a volar to dorsal direction from increased rotation between the carpal bones. The classification of carpal instability is based arthroscopic observation of the interosseous ligament from the radiocarpal and midcarpal spaces, and it evaluates injuries to the scapholunate and lunotriquetral interosseous ligaments (Table 26-1).

TABLE 26-1 Geissler Arthroscopic Classification of Carpal Instability

Grade	Description	Management
I	Attenuation or hemorrhage of the interosseous ligament is seen from the radiocarpal joint. There is no incongruence of carpal alignment in the midcarpal space.	Immobilization
II	Attenuation or hemorrhage of interosseous ligament is seen from the radiocarpal joint. Incongruence or step-off is seen from the midcarpal space. A slight gap (less than width of a probe) between the carpal bones may be present.	Arthroscopic reduction and pinning
III	Incongruence or step-off of carpal alignment is seen in the radiocarpal and midcarpal spaces. The probe may be passed through the gap between the carpal bones.	Arthroscopic or open reduction and pinning
IV	Incongruence or step-off of carpal alignment is seen in the radiocarpal and midcarpal spaces. Gross instability with manipulation is identified. A 2.7-mm arthroscope may be passed through the gap between the carpal bones.	Open reduction and repair

In the Geissler classification, grade I injuries have a loss of the normal concave appearance between the carpal bones as the interosseous ligament attenuates and becomes convex, which can be seen with the arthroscope in the radiocarpal space. Hemorrhage may be seen within the ligament in acute injuries, such as a fracture. In the midcarpal space, the interval between the carpal bones is congruent, and there is no step-off.

In Geissler grade II injuries, the interosseous ligament continues to attenuate and becomes convex as seen from the radiocarpal space. There is no gap between the carpal bones when viewed with the arthroscope in the radiocarpal space. In the midcarpal space, an interval between the carpal bones is no longer congruent, and a step-off exists. In scapholunate instability, palmar flexion of the scaphoid, compared with the lunate, can be seen arthroscopically. The dorsal lip of the lunate is distal in relation to the lunate. In lunotriquetral instability, increased translation is seen through the triquetrum and lunate when palpated with a probe.

In Geissler grade III injuries, the interosseous ligament starts to tear, usually in a volar to dorsal direction, and a gap is seen between the involved carpal bones and the radiocarpal space. The probe can be used to separate the involved carpal bones in the radiocarpal space. In the midcarpal space, a 2-mm probe may be placed between the carpal bones and twisted. A portion of the interosseous ligament is still intact, and complete disruption of the interosseous ligament is not observed.

In Geissler grade IV injuries, the interosseous ligament is completely detached and disrupted. The drive-through sign occurs when the arthroscope may be freely passed through the radiocarpal space and the torn interosseous ligament into the midcarpal space.

TREATMENT

Management of Carpal Instability

Geissler grade I injuries are consistent with a typical wrist sprain, and these tears respond to a short period of immobilization. Geissler grade II and III injuries may be easily arthroscopically reduced and stabilized in an acute situation. Anatomic reduction of the carpal interval is best viewed with the arthroscope in the midcarpal space opposite to the tear. For example, correction of the rotation to scapholunate instability is best viewed with the arthroscope in the ulnar midcarpal portal. For lunotriquetral instability, the reduction is best viewed with the arthroscope in the radial midcarpal portal. The carpal interval is reduced, and Kirschner wires are placed across the involved interval in oscillation mode to protect the cutaneous nerves. Geissler grade IV injuries have complete detachment of the interosseous ligament, and open repair is recommended for the best prognosis in acute situations.

Arthroscopic Techniques

A patient who sustains a fracture of the distal radius usually presents with a swollen wrist. Because of the swelling, it is usually difficult to palpate the extensor tendon landmarks traditionally used for arthroscopy. However, the bony landmarks are usually easily palpated, and they include the bases of the metacarpals, the ulnar head, and the dorsal lip of the radius.⁷

The wrist is suspended in a traditional traction tower. The standard 3-4 portal is made between the third and fourth dorsal extensor compartments. The 3-4 portal is made in line with the radial border of the long finger when the extensor tendons cannot be palpated. I recommend placing an 18-gauge needle into the proposed location of the 3-4 portal before committing to a skin incision. The arthroscope may be placed within the fracture itself if the portal is placed too proximal or can injure the articular cartilage of the carpus if the portal is placed too distally. After the precise location of the portal is determined, the portal is made on the skin against the surgeon’s thumb with the tip of a no. 11 blade. In this manner, the possibility of injury to the dorsal sensory cutaneous branches is decreased. Blunt dissection is continued with a hemostat to the level of the joint capsule, and the arthroscope is then reduced with a blunt trocar inserted into the 3-4 portal.

Intra-articular fractures of the distal radius are usually associated with abundant fracture hematoma and debris.⁸ Thorough irrigation of the fracture hematoma is required to evaluate the fracture fragments and to improve the field of view to judge rotation to the fracture fragments. Inflow may be provided through the wrist arthroscopic cannula or through a 14-gauge needle inserted into the 6-U portal. The small cannula used in wrist arthroscopy does not allow much space between the cannula itself and the arthroscope to allow fluid irrigation into the wrist joint. Because of this, separate inflow through the 6-U portal is recommended. Outflow is provided through the arthroscopic cannula with, intervenous extension tubing that drains into a basin on the hand table so the fluid does not go into the surgeon’s lap or onto the floor. Separate inflow and outflow cannulas limit fluid extravasation into the soft tissues.

The 4-5 or 6-R working portal may be used to remove debris and hematoma to improve visualization. The 4-5 working portal is made in line with the midaxis of the ring metacarpal when the extensor tendons cannot be palpated. The 6-R portal may be made just radial to the extensor carpi radialis tendon. Similarly to making the 3-4 portal, an 18-gauge needle should be inserted into the proposed location and viewed arthroscopically before committing to a skin incision.

The ideal timing for arthroscopically assisted reduction of intra-articular distal radius fractures is usually between 3 and 10 days.⁹ Other attempts at arthroscopic fixation may result in troublesome bleeding, which may obscure visualization. Fractures more than 10 days old may be difficult to disimpact and mobilized percutaneously.