Carpal coalition the fifth to eighth weeks. The lunate and triquetral bones are the most common carpal bones to fuse together, resulting in a lunotriquetral coalition in 1% of people. 60% of patients with a lunotriquetral coalition will have it bilaterally. Among isolated incidents the capitate and hamate bones are the next most common to fuse followed by the pisiform-triquetrum, trapezium-trapezoid, scaphoid-capitate, and triquetrum-hamate. Carpal coalitions may further be divided into four subtypes: Generally since carpal-carpal fusions do not cause unease or discomfort for the patient, and do not impair wrist function, treatment is not needed. However, in the minority of cases
Carpal bones proximal row (comprising scaphoid, lunate, and triquetrum) articulates with the surfaces of the radius and distal carpal row, and thus constantly adapts to these mobile surfaces. Within the proximal row, each carpal bone has slight independent mobility. For example, the scaphoid contributes to midcarpal stability by articulating distally with the trapezium and the trapezoid. In contrast, the distal row is more rigid as its transverse arch moves with the metacarpals. Biomechanically and clinically, the carpal bones are better conceptualized as three longitudinal columns: In this context the pisiform is regarded as a sesamoid bone embedded in the tendon of the