Page 22 - Delaware Medical Journal - March/April 2019
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FIGURE 7
AB
FIGURE 8
A
B
A. Left CH coalition, boy, age 2y0m
B. Right CH coalition, boy, age 2y7m. CH, capito- hamate
A. Left CH coalition,
boy, Apert syndrome, age 1y0m
stages correspond to Minnaar types 1 through 3, respectively, suggesting that some individuals do not complete the fusion, but rather arrest at some stage of partial fusion.
radiographically in pre-adolescence, with the “parallel cortex” sign seen from ages 7 to 13 years in our group. Partial bony coalition progressing to complete coalition with “zippering” similar age range suggests the transition between these stages may be rapid. In fact, this transition occurred during a two- month period between sequential radiographs at age 13 in one of our cases.
The four cases of CH coalitions were visible at a much earlier
as 2 years 8 months of age, ranging up to 6 years 2 months before bony bridging. The hamate appeared larger than expected in three cases, being equal to or larger than the capitate, which is the opposite of normal comparison examples in the Greulich
and Pyle atlas.25 In the fourth case, this relationship could not be assessed due to timing of the radiographs. As bony development capitate and hamate cortices were observed, similar to LT coalition. As bony fusion ensued, though, a “zippering” effect was not clearly seen. Notching, when present, was more poorly bilateral CH coalition was seen in both.
Capito-hamate coalition, conversely, occurs at a much earlier age. Hughes and Tanner described four cases with observed evolution of CH coalition, noting bony fusion by approximately 8 years of age. All four cases in our series showed bony fusion by age 6 years. Other signs of developing CH coalition, including larger hamate ossicle size than expected for the child’s age (equal to or larger than the adjacent capitate) as well as the parallel cortex sign, can be seen as early as 1 year 6 months. Capito- hamate coalition appears more closely tied to syndromes than LT coalition, with three of four children in the CH coalition group having an underlying syndrome whereas only two of eight did in the LT coalition group.
This study is limited because of the small sample size, and no
sex differences could be explored because of this limitation. In addition, radiographs were obtained for clinical indications at varied time intervals — some as short as two months and others as long as six years between images. Therefore, we cannot became apparent. Nonetheless, the typical patterns and general age ranges could be gleaned.
C age 5y3m. CH, capito-hamate
DISCUSSION
Carpal coalition is a rare condition affecting wrist bones. In most cases, it is asymptomatic. This study is a summary of 12 children with LT and CH coalitions for whom sequential imaging studies were performed during growth, illustrating the radiographic evolution of this process during development.
Minnaar described four types of LT fusion based on an
adult population. The four types described are as follows:
1) incomplete fusion representing a pseudarthrosis, 2)
fusion with a notch of varying depth found distally, or
distally and proximally, 3) complete fusion of the lunate and triquetrum, and 4) complete LT fusion with other associated anomalies.26 Our cases illustrate the common sequence of
LT fusion in childhood, with close apposition of the lunate
and triquetrum with parallel cortices leading to partial bony progressing distally across the width of the bones. These
B. Left CH coalition, boy, Apert syndrome, 4y9m
C. Left CH coalition, boy, Apert syndrome,
age
70
Del Med J | March/April 2019 | Vol. 91 | No. 2
