Incomplete left-hand and complete right-hand pisiform and hamate coalition: multidetector computed tomography findings

Abstract

Pisiform-hamate coalition is a rare form of carpal coalition. Only 14 cases of pisiform-hamate coalition have been reported in the English-language literature. We present a case of asymptomatic bilateral pisiform-hamate coalition in a 16-year-old boy. We also review the embryology, pathogenesis, and clinical features of pisiform and hamate coalition, along with the associated multidetector computed tomography findings.

A case of a painful coalition between pisiform and hamate

“…Most of the reported symptomatic cases were type 1 or 2 coalition because minor movement between the pisiform and hamate can cause cartilage degeneration and pain. In contrast, most asymptomatic pisiform-hamate coalitions previously reported were types 3 and 4 [6].…”

“…As a sesamoid, the pisiform forms no cartilaginous connection to the hamate throughout its entire period of ossification [5]. This rare anomaly is considered to result from the metaplastic conversion of ligament into bone [6]. As first devised by Minaar in 1952 [7] to categorise the lunate-triquetrum fusions based on radiographs, Minaar's classification has been used to categorise all carpal coalitions.…”

Hook of the Hamate: The Spectrum of Often Missed Pathologic Findings

“…However, pisiform-hamate coalition does not develop in this way. The pisiform is a sesamoid bone related to the flexor carpi ulnaris tendon and arises from its own endochondral ossification center [27, 32, 33]. The mechanism of pisiform-hamate coalition has been posited to result from metaplasia of the pisohamate ligament or ossification of the distal flexor carpi ulnaris [32].…”

“…Several cases of asymptomatic pisiform-hamate coalition have been described [27, 33, 35]. Symptomatic pisiform-hamate coalition has been reported to occur with or without associated trauma.…”

Case report: Co-existent of lunotriquetral coalition with pisiform-hook of hamate coalition in the same wrist joint: An incidental radiographic finding

“…As a sesamoid, the pisiform has no cartilaginous connection to the hamate throughout its period of ossification [4] . This rare anomaly is suggested to be the result of metaplastic conversion of ligament into bone [5] . Acquired carpal coalition could be a result of multiple inflammatory arthropathies including rheumatoid arthritis, juvenile arthritis, psoriatic arthritis, and Reiter's syndrome and others [1] .…”