What Is the Best Treatment for Acute Injuries of the Scapholunate Ligament?

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Chapter 13 What Is the Best Treatment for Acute Injuries of the Scapholunate Ligament?

PAUL. BINHAMMER, MSc, MD, FRCS(C)

The scapholunate (SL) ligament is the fibrous structure that links the scaphoid and lunate bones of the wrist. It is composed of a thick and strong dorsal portion, a more pliable anterior portion, and finally an intervening membranous segment. It is the dorsal portion that plays the most important role for carpal stability.

Injury to the ligament usually occurs as a result of a fall on an outstretched hand resulting in wrist hyperextension, ulnar deviation, and midcarpal supination. Although the ligament can be injured in isolation, and the diagnosis missed, it can also be injured with fractures of the distal radius or scaphoid, which should raise clinical suspicion just as in perilunate dislocations.

Diagnosis of scapholunate dissociation (SLD) can usually be made on physical and radiologic examinations. Physical examination usually demonstrates localized tenderness and a positive scaphoid shift test. If there is a complete tear, radiologic findings may include an increased SL joint space and a “ring” sign where the scaphoid has an overlying ring or circle projection caused by its volar flexion deformity. Other tools that aid in the diagnosis are cineradiography, arthroscopy, and arthrography.

An acute injury to the SL ligament alters the linkage between the two bones resulting in a dissociative carpal instability, also known as an SLD. This can present clinically in a variety of stages depending on the severity of the original injury and the delay to clinical diagnosis. There is no consensus for the nomenclature for the various patterns of severity of SL injuries. Predynamic SLD is a partial injury where the ligament remains intact. Symptoms arise from the associated increase motion, but there is no instability. Dynamic SLD is a complete disruption of the ligament when it is still repairable. No cartilage damage exists, and secondary stabilizers are intact. No permanent malalignment and demonstration of the radiographic gap between the scaphoid exists, and the lunate may require special maneuvers. The third manifestation is static reducible SLD. Secondary stabilizers have become deficient. The radiographic appearance is quite apparent, but the deformity can still be reduced. Eventually, the insufficiency results in static fixed SLD where it cannot be reduced. Finally, there is progression to degenerative arthritis with cartilage loss resulting in scapholunate advanced collapse (SLAC) wrist.¹ The rationale for treatment of acute SL injuries is to prevent the progression to a SLAC wrist.

SURGICAL TREATMENT OPTIONS

Acute injuries to the SL ligament are either predynamic or dynamic. Predynamic injuries may not always present acutely because the ligament is still intact and the time to diagnosis can be delayed. In acute predynamic cases, treatment is directed toward giving the stretched ligaments time to heal. The options indicated in the literature for management are either percutaneous fixation or arthroscopically guided fixation of the SL joint.

Dynamic SL injuries can present a spectrum of injury patterns to the ligament and have a variety of treatment. The ligament injury can be midsubstance, avulsed with or without bone. The quality of the ligament available for repair is also variable. The available options for treatment are closed reduction and cast immobilization, open reduction internal fixation and repair of the dorsal SL ligament, dorsal radioscaphoid capsulodesis, and other forms of acute reconstruction.

EVIDENCE

Predynamic Injuries

For acute predynamic SL injuries, this is primarily a diagnosis based on findings at the time of arthroscopy, and consistent symptoms and physical examination. No series in the literature have examined treatment of these patients conservatively either by observation alone or by casting. The evidence for percutaneous fixation for these injuries is limited to management review articles and book chapters.²^–⁴

The evidence for arthroscopically guided fixation for acute incomplete injuries is also lacking. Studies for chronic symptoms and arthroscopic management of various types of wrist injuries have been reported; however, there are no acute injury case series.⁵^–⁸ Whipple⁹ reported a non–peer-reviewed article on arthroscopically guided pin fixation in a series of 40 patients. In a subgroup of these 40 patients, with less than a 3-mm gap and less than 3 months of symptoms, 83% experienced symptom relief. However, the size of this subgroup and the severity of SL injury are not identified, and neither is the time from injury. Hirsh and colleagues ¹⁰ have reported on arthroscopic electrothermal shrinkage for SL laxity in 10 patients, of which there were 2 that were less than 6 weeks after injury. The outcomes for these two patients are unclear.

Dynamic Injuries

Cast Immobilization.

Two case reports of successful management of an SLD associated with a distal radius fracture (DRF) managed by closed reduction and casting have been reported.^11,¹² However, Tang and coworkers,¹³ in a series of 20 patients with DRF and SLD, found at 1 year that 100% had clinical signs and positive radiographs. Eight patients underwent surgery at 1 year. Laulan and Bismuth,¹⁴ in a radiographic study of DRF in 29 patients with an SL injury treated by casting alone, found at 1 year that progressive carpal collapse occurred in 61% of patients.

K-Wire Fixation.

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