Synonyms in a broader sense
Scapholunary dissociation, scaphoid dislocation, ligament injury of the carpus, distal radius fracture, hand injury
Definition
In scapholunar dissociationSLD, external force is used to injure the ligaments in the carpal area between the scaphoid bone (Os scaphoideum, formerly Os naviculare) and the lunate bone (Os lunatum).
Cause
Scapholunar dissociationSLD is the second most common accidental carpal disorder after scaphoid fracture. Scapholunar dissociationSLD can only occur as a result of an accident and can occur in combination with a distal radius fracture. Typical accidental events are a fall on the extended wrist.
Grade 3: Complete rupture of the ligamentous apparatus between the scaphoid and the lunate bone with visible malposition and dissociation of the lunate bone (Os lunatum) and scaphoid (Os scaphoideum, formerly Os naviculare). Compare the healthy wrist below, there is no distance between the scaphoid bone (1.) and the lunate bone (2. ).
Symptoms
Typical symptoms of scapholunar dissociationSLD are pain in the wrist area, and especially pain in the scaphoid. These cannot be distinguished from a scaphoid fracture or wrist fracture without further examination by the physician. In some cases, so-called clicking noises are audible and snap phenomena are visible and palpable, which are caused by cartilage damage.
Wrist mobility is significantly restricted due to the lack of movement of the first row of wrists. Due to the incorrect position of the carpal bones scaphoid bone (Os scaphoideum) and lunate bone (Os lunatum), the strength in the wrist is reduced. If this injury persists over a longer period of time, a swelling can be felt above the back of the hand, which is caused by a proliferation of the joint mucosa (synovitis), can be palpated.
Classification
Scapholunar dissociations are classified into three degrees of severity. Grade 1: Partial rupture of the ligamentous apparatus between the scaphoid and the lunar bone without detectable instability Grade 2: Partial rupture of the ligamentous apparatus between the scaphoid and the lunar bone with provocative instability
- Scaphoid bone (Os scaphoideum)
- Moon leg (Os lunatum)
- Pea leg (Os pisiforme)
- Triangular leg (Os triquetum)
- Hooked leg (Os hamatum)
- Capitate bone (Os capitatum)
- Small polygon bone (Os trapezoidum)
- Large polygonal bone (Os trapezium)
