In addition, many carpal coalitions are familial. The most common site of coalition is between the lunate and triquetrum. It occurs most frequently in black males. The coalition may not be easily identifiable owing to the fact that many are incomplete. The majority, however, will demonstrate osseous fusions.
Carpal coalition is secondary to a developmental abnormality.
It is believed to be due to a delay in the natural programmed cell death leading to joint cavitation. Resnick C. Incomplete Carpal Coalition. Resnick D. Diagnosis of Bone and Joint Disorders.