SLAC wrist in the absence of recognised trauma and CPPD

Area of Science:

• Orthopedic surgery
• Biomechanics
• Radiology

Background:

• Scaphoid, lunate, advanced collapse (SLAC) wrist is typically associated with trauma.
• The existence and etiology of non-traumatic SLAC wrist remain unclear.

Purpose of the Study:

• To investigate the existence of non-traumatic SLAC wrist.
• To determine if non-traumatic SLAC wrist is associated with abnormal carpal bone kinematics, specifically reduced lunate flexion.

Main Methods:

• A prospective comparative cohort study.
• Non-traumatic SLAC wrist patients were compared with an age-matched control group.
• Radiographic kinematic analysis was performed.

Main Results:

• Thirty-three non-traumatic SLAC wrists and 36 control wrists were analyzed.
• Non-traumatic SLAC wrists exhibited significantly different radiographic kinematics compared to controls.
• In non-traumatic SLAC wrists, 70% of flexion occurred through the lunocapitate (LC) joint and 30% through the radiolunate (RL) joint, versus 48% LC and 52% RL in controls.

Conclusions:

• Non-traumatic SLAC wrist appears to exist.
• Abnormal wrist kinematics, potentially due to dorsal radiolunate ligament restriction of lunate flexion, may initiate non-traumatic SLAC wrist development.
• This can lead to increased scapholunate angles and eventual scapholunate ligament degeneration.