A 46-year-old male presented with left wrist pain after falling on an outstretched hand on ice. Examination revealed clicking in the wrist with movement and pain with wrist rotation. X-rays showed signs suggestive of scapholunate dissociation, a ligament injury between the scaphoid and lunate bones that if left untreated can lead to wrist instability and arthritis. The patient was referred to orthopedics for surgical repair of the injured ligament.

2.  46yo male presents with  T 98.4 P 74 BP 138/80
chief complaint of left O2 100%
wrist pain. Patient  Gen NAD
slipped on side walk on  MSK pain to dorsum of
sheet of ice and fell left wrist just proximal to
forward, landing on 3rd metacarpal. 2+ distal
outstretched hand. Pain pulses. Pain with wrist
has been lingering for rotation
past two days, and pt
endorses “clicking”  Neuro: motor 5/5 nl
sound with certain wrist sensation
movements

4.  scapholunate dissociation
 scaphoid impaction syndrome (SIS)
 occult ganglion cyst
 posterior interosseous nerve neuroma
 physiologic scapholunate (compare to other hand)
 perilunate dislocation
 non-displaced scaphoid fx

5. White arrow: "Terry Thomas"sign gap between scaphoid and lunate, normal 1-2 mm
(abnormal 3mm) Progressive flexion and foreshortening of the scaphoid leads to the scaphoid
ring sign, seeing scaphoid end on.
Black arrow: Signet Ring sign- seen with abnormal palmar flexion of scaphoid.
Right Image: Scapholunate angle nl 30-60 degrees, >80 degrees diagnostic of DISI (dorsal
intercalated segment instability) signifying carpal instability

6.  Orthopedic follow up, for most cases will need
operative repair of interosseous ligament.
 Can place patient in thumb spica splint and have
patient f/u with ortho within one week.
 Untreated, SLD can lead to DISI, defined by SL angle
>80 degrees due to abnormal flexion of
scaphoid, indicating wrist instability, and if further
untreated, can lead to severe arthritis; thus prompt
ortho f/u necessary

7.  MCC of carpal instability
 Assoc. injuries: simultaneous radial styloid fx is relatively
common w/ carpal dislocation; also always consider non-
displaced scaphoid fx.
 Mechanism is similar to that of scaphoid fx, w/ stress
loading of extended carpus, except it is usually in ulnar
rather than radial deviation
 SL angle greater than 80 degrees indicative of DISI, which
can occur with SLD left untreated, and is indicative of
worsened carpal instability.
 DISI can lead to scapholunate advance collapse (SLAC), a
specific pattern of osteoarthritis and subluxation which
results from untreated chronic SLD.

9.  http://www.wheelessonline.com/ortho/scapholunate_
instability
 http://fhs.mcmaster.ca/surgery/documents/scapholu
nate_dissociation.pdf
 http://www.rcsed.ac.uk/fellows/lvanrensburg/classific
ation/hand/scapholunate_diss.htm
 http://emedicine.medscape.com/article/1244215-
overview
 http://www.radsource.us/clinic/0906
 http://www.wheelessonline.com/ortho/x_ray_findings
_in_sld