Pocket Orthopaedic Surgery by Boughanem Jay (Jamal) & Shah Ritesh R

Author:Boughanem, Jay (Jamal) & Shah, Ritesh R.
Language: eng
Format: epub
ISBN: 978-1-4698-8488-2
Publisher: LWW
Published: 2015-07-28T16:00:00+00:00

CARPAL INSTABILITY AND WRIST ARTHROSCOPY

MICHAEL D. SMITH • CLAUDE D. JARRETT

CARPAL INSTABILITY

The loss of synchronous balance and alignment of the carpal bones that can result in altered wrist kinematics producing pain, weakness, and premature arthritis.

Anatomy and Kinematics

• Carpal bones: Wrist is composed of 8 carpal bones arranged in 2 rows.

• Proximal row: Scaphoid, lunate, triquetrum, pisiform

• Distal row: Trapezium, trapezoid, capitate, hamate

• Intrinsic ligaments: Ligaments, which attach directly between carpal bones.

• Primary intrinsic ligaments of the proximal row are the scapholunate (SL) and lunotriquetral (LT) ligaments.

• SL is thicker dorsally; LT is thicker volarly.

• Ligaments help stabilize and balance the lunate against the opposing forces of scaphoid flexion and triquetral extension.

• Extrinsic ligaments: Between radius/ulna and carpal bones (radiocarpal ligament, ulnolunate ligament, etc.)

• Kinematics

• Distal row bones are rigidly connected to the metacarpal base by stout ligaments.

• This allows the distal row to be controlled by the extrinsic wrist extensor and flexor tendons.

• Proximal row carpal bones do not have any direct attachments to the extrinsic wrist tendons.

• They are relatively freely positioned between the distal radius and the distal row and the row is commonly referred to as an “intercalated segment.”

• Thus, its movement is controlled by the action of the distal row.

• The scaphoid and the triquetrum are thought to be the important links between the distal row and the proximal row.

• Their motion is controlled secondary to the forces placed on them and the articulations with the distal row.

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