Assistant
Definition
By Gregory R. Waryasz, MD
The triquetrum of the musculoskeletal system is characterized by being three-cornered. It is located on the ulnar side of the hand but does not articulate with the ulna.
It is part of the upper limb. The triquetrum articulates with the lunate, pisiform, hamate, and the articular disc of the distal radioulnar joint. It consists of bone and cartilage tissue once mature.
Its unique structural features include its being shaped like a pyramid. It is an ulnarly located bone of the proximal carpal row.
The superior surface has a rough non-articular surface and a convex articular portion to articulate with the triangular articular disc of the wrist.
The inferior surface is concave and articulates with the hamate.
There is an oval shaped facet on the volar surface where the pisiform bone articulates.
The articulation surface with the lunate is flat with a quadrilateral facet.
The attachment for the ulnar collateral ligament is at the summit of the pyramid. The attachment surface is pointed and rough.
The triquetrum ossifies at age 3. The triquetrum as well as all other bones, muscles, and ligaments of the body are derived of mesodermal origin in embryo.
The function of the triquetrum is to extend with compressive loads. It helps to move the lunate into extension. The triquetrum articulates with the articular disc of the distal radioulnar joint.
Common diseases of the triquetrum include arthritis, fracture, and dislocation.
Arthritis can occur at any of the articulations. Common arthritis types that can occur at these locations include osteoarthritis and rheumatoid arthritis.
Fracture of the triquetrum can occur with trauma. It is the third most common carpal bone fracture after the scaphoid and lunate.
Dislocation of the triquetrum can occur with trauma.
Commonly used diagnostic procedures include clinical history, physical exam, x-ray, MRI, bone scan, and CT scan.
It is usually treated with non-operative or operative approaches for fractures. Dislocations are usually treated operatively. Arthritis is treated initially with physical therapy, NSAIDs, and steroid injections.
References
Elstrom J, Virkus W, Pankovich (eds), Handbook of Fractures (3rd edition), McGraw Hill, New York, NY, 2006.
Koval K, Zuckerman J (eds), Handbook of Fractures (3rd edition), Lippincott Williams & Wilkins, Philadelphia, PA, 2006.
Lieberman J (ed), AAOS Comprehensive Orthopaedic Review, American Academy of Orthopaedic Surgeons, 2008.
Moore K, Dalley A (eds), Clinically Oriented Anatomy (5th edition), Lippincott Williams & Wilkins, Philadelphia, PA, 2006.