Scapholunate Ligament Disruption is an injury involving the ligaments attaching the scaphoid to the lunate. There is a dorsal and volar ligament as well as proximal ligament which connect these two carpal bones.
Mechanism of Injury:
Traumatic injury of wrist while in extension resulting in disruption, most commonly, of the dorsal scapholunate ligament. This is also known as a DISI (Dorsal Intercalated Segmental Instability) injury. (1,2)
Inspection – may notice some edema
Palpation – swelling, or occasionally ganglion cyst in older injuries.
AROM – reduced extension and extension may be present in acute and chronic injury
PROM – may have restriction and pain at end range extension and flexion
Special Tests – Anterior-posterior translation of lunate-scaphoid will be increased on affected side. Watson’s Test – volar-sided pressure on the scaphoid while moving wrist from ulnar to radial deviation reveals a clunk in the location of the scapholunate joint.
Xray – AP, Lateral – can assess scapholunate angle (see Xray example) (3), Clenched fist
CT – Will allow viewing of the scaphoid and lunate as well as gapping if present.
MRI – Will demonstrate ligamentous injury as well as gapping between scaphoid and lunate.
Case: 32 year old male left wrist – pain and clunking in radial side of wrist
See Imaging below:
Figure 1 – AP SL no widening Figure 2 – Lateral (normal Scapholunate angle 30-60 deg)2
Figure 2 – Clenched fist view: Allows clinician to assess
scapholunate stability. Widening
of Scapho-Lunate interval.
Figure 4 – Scapholunate angle between lines A and B (Line A – through midline of proximal end of scaphoid through midline of distal end of scaphoid, Line B – through midline of proximal lunate through midline of distal lunate )
MRI Left Wrist: Axial, Sagital, Coronal, Coronal, Coronal
Management: Acute injuries initially treated with immobilization with fixed splint. While awaiting referral to hand and upper limb clinic or equivalent. If injury persists with pain as well as instability despite conservative measures the patient will require surgical intervention. Left untreated, the scapholunate instability can lead to scapholunate advance collapse (SLAC wrist).
(1) Review of orthopaedics. 5th ed. ed. Philadelphia: Saunders / Elsevier; 2008.
(2) Phillips B, Gest T. Wrist Joint Anatomy. 2013; Available at: http://emedicine.medscape.com/article/1899456-overview#aw2aab6b3.
(3) Rispoli DM. Tarascon pocket orthopaedica. 3rd ed. ed. Sudbury, Mass.: Jones and Bartlett Publishers; 2010.
(April 23, 2014) Dr. Neil Dilworth CCFP Dip Sport Med (PR WC)