The scapholunate ligament (SLL) is a fibrous connective tissue structure within the wrist that connects the scaphoid and lunate carpal bones. It is a component of the intrinsic carpal ligamentous complex and plays a crucial role in maintaining the stability and coordinated motion of the proximal carpal row.
Anatomical location and structure
- The ligament extends radially from the dorsal surface of the scaphoid to the dorsal surface of the lunate, although it also has palmar and interosseous (central) components.
- It consists of dense regular collagen fibers organized into three distinct portions: dorsal, volar (palmar), and central (or interosseous) bands. The dorsal band is the strongest and most clinically significant portion.
- The ligament is approximately 10–12 mm in length and varies in thickness, being thicker dorsally (≈2 mm) than volarly (≈1 mm).
Function
- The scapholunate ligament stabilizes the scaphoid and lunate relative to each other, preventing excessive separation (diastasis) and abnormal rotation of the scaphoid during wrist motion.
- By maintaining the alignment of the scaphoid and lunate, the ligament contributes to the proper transmission of loads across the wrist joint and preserves the “dart‑thrower” motion (combined flexion/extension and radial/ulnar deviation).
Vascular supply and innervation
- Vascularization is derived primarily from branches of the radial and ulnar arteries that penetrate the ligament from surrounding capsular tissue.
- Innervation is provided by small branches of the dorsal and palmar interosseous nerves, which convey proprioceptive information.
Clinical relevance
- Injury: Traumatic rupture of the scapholunate ligament is the most common carpal ligament injury and typically results from a fall onto an outstretched hand or direct compression. Acute tears may present with wrist pain, swelling, and reduced range of motion. Chronic insufficiency can lead to scapholunate dissociation, manifested radiographically as a widened scapholunate gap (>3 mm) and a characteristic “DISI” (dorsal intercalated segment instability) deformity of the lunate.
- Diagnosis: Assessment includes physical examination (e.g., Watson’s test), plain radiography, and advanced imaging such as magnetic resonance imaging (MRI) or wrist arthroscopy for direct visualization.
- Management: Treatment varies with injury severity. Conservative measures (immobilization) are employed for partial tears, whereas complete ruptures often require surgical repair or reconstruction (e.g., dorsal capsulodesis, ligament augmentation, or tendon grafting). Early intervention aims to prevent progressive osteoarthritis of the wrist.
Biomechanical studies
- Cadaveric and in‑vivo investigations have demonstrated that disruption of the dorsal band of the SLL produces the greatest increase in scapholunate gap and loss of carpal stability, underscoring its primary stabilizing role.
Historical context
- The term “scapholunate” combines the Greek “scapho‑” (derived from skaphe meaning “boat,” referencing the boat‑shaped scaphoid bone) and “lunate” (from Latin luna, meaning “moon,” referring to the crescent‑shaped lunate bone). The ligament was first described in detail in early 20th‑century anatomical texts focusing on carpal biomechanics.
References
- Gelberman RH, et al. “Scapholunate Ligament Injuries.” The Journal of Hand Surgery (American Volume), 1992.
- Weiss KE, et al. “Biomechanics of the Scapholunate Ligament.” Hand Clinics, 2003.
- Manske PR, et al. Hand Surgery. 2nd ed., Elsevier, 2015.
This entry reflects current, peer‑reviewed anatomical and clinical knowledge as of 2026.