Scaphoid

Brief description This species is <1 m tall. Its side branches may be pinnate (paired on opposite sides of the main branches) but often are not pinnate. The distinguishing features of Pseudopterogorgia elisabethae are its short, stout branchlets, large, moderately pointed scaphoids with nearly or quite smooth convex surface, and large anthocodial rods. It is moderately slimy, but not as much as is the case with Pseudopterogorgia americana. The colonies may be either yellow or purple. 

Brief description Pseudopterogorgia kallos is very close to the shrubby examples of P. bipinnata but can, in summary, be recognized by (1) the bushy habit of growth, with steeply ascending twigs not strictly in one plane and not always opposite (2) the scaphoids with the spaces between the crests of the convex side filled in except for the median constriction and (3) the short anthocodial rods with noticeably clubbed ends. 

Brief description Branching planar, pinnate, and plumose. Short and very narrow lateral branches arise from the main stem. The lateral branches do not branch further. Sclerites range in length from 0.05 to 0.16 mm, and are straight or slightly curved spindles with three to six transverse whorls of tubercles. Some scaphoids are distinct and have smooth tubercles on the convex side, while others are less distinct and have ornamented tubercles on both the convex and concave sides. The sclerites are yellow or red. ... 

Studies of the normal biomechanics of the proximal wrist joint have determined that the scaphoid and lunate bones have separate, distinct areas of contact on the distal radius/triangular fibrocartil-age complex surface [Viegas et al., 1987] so that the contact areas were localized and accounted for a relatively small fraction of the joint surface, regardless of wrist position (average of 20.6%). The contact areas shift from a more volar location to a more dorsal location as the wrist moves from flexion to extension. Overall, the scaphoid contact area is 1.47 times greater than that of the lunate. The... 

Linscheid et al. popularized a different concept, the slider/crank theory where the scaphoid was seen as the bone that bridged the proximal and distal carpal row and, by bringing it back into its correct anatomic position, the stability of the wrist could be re-established. 

So, finally we return to the analogy of carpal collapse. Because we could not stabilize the scaphoid, the carpus collapsed. In the lumbar spine, we could not stabilize L5 in its correct position in relationship to the sacrum, and the lumbar spine collapsed and kyphosed. 

These are specialised views to demonstrate the scaphoid hone. The scaphoid hone is not ossified in... 

Oblique view of the scaphoid bone with ulna deviation (the hand and wrist is rotated 45 from the PA position by raising its lateral aspect). 

Ulna deviation is achieved by moving the fingers as far as possible towards the ulna and stretching the thumb towards the radius. The anatomical snuffbox formed at the base of the thumb in this position indicates the position of the scaphoid bone (Fig. 2.27). 

Fig. 2 27a-e. Scaphoid bone, a PA scaphoid with ulna deviation, b Lateral wrist, c 45° Oblique scaphoid with ulna deviation, d 35°angled PA scaphoid view with ulna deviation, e Resultant Radiographs... 

With acute paediatric trauma, standard radiographs remain the predominant imaging modality, with MRI being used as an adjunct. MRI is useful in detecting some acute injuries such as scaphoid fractures. In other circumstances it is of limited value, being relatively insensitive in detecting small os-sific fragments within a joint and when there is a considerable amount of metallic hardware within the bone. 

The use of MRI is not routinely indicated in the acute setting however, it is being increasingly utilised for scaphoid injuries (Johnson et al. 2000). 

Fig. 5.10. Oblique coronal STIR image of the scaphoid. There is extensive marrow oedema with fluid around the carpal bones, features in keeping with a scaphoid fracture. Radiographs were normal.

Avascular necrosis can potentially complicate any fracture but is thankfully relatively rare in the younger child. In the older teenager with a scaphoid or femoral head fracture, dislocation then avascular necrosis is a more significant risk. 

Jaramillo D, Shapiro E et al. (1990) Post-traumatic growth-plate abnormalities MR imaging of bony-bridge formation in rabbits. Radiology 175 767-773 Johnson KJ, Haigh SP et al. (2000) MRI in the management of scaphoid fractures in skeletally immature patients. Pediatr Radiol 30 685-688... 

Fig. 7.24. Normal developmental notch and hook in the scaphoid (arrow)...

Fig. 19.33. Scaphoid views of the wrist performed in a 12-year-old boy show a dorsal buckle fracture of the radius...

The ossific nucleus of the scaphoid appears around 4-6 years of age, and ossification is complete at 13-15 years. As in adults, the scaphoid is the most frequently injured carpal hone. The incidence of fractures is extremely low in the first decade, thereafter rising to a peak in the late teens to mid twenties (Grad 1986). Unlike adults, fractures of the distal pole are more common than of the waist (Fig. 19.34). These fractures represent ligamentous avulsion injuries, with failure through the bone rather than the stronger soft tissues. Middle third fractures occur in older children and adolescents, whilst proximal pole fractures are rare. Many fractures are the result of direct trauma to the wrist rather than a fall on the outstretched hand (Vahvanen and Westerlund 1980). 

Fractures of the other carpals are very rarely seen in children (Goddard 2005). The capitate maybe injured in isolation, or more typically, in conj unction with other carpals, particularlythe scaphoid (Anderson 1987). Rare cases of lunate dislocations have been reported, usually associated with other injuries (Giddins and Shaw 1994) (Fig. 19.35). Open reduction and repair of the intercarpal hgaments is advised. 

A1 Qattan MM (2002) Juxta-epiphyseal fractures of the base of the proximal phalanx of the fingers in children and adolescents. J Hand Surg [Br] 27 24-30 Anderson WJ (1987) Simultaneous fracture of the scaphoid and capitate in a child. J Hand Surg [Am] 12 271-273 Barton NJ (1979) Fractures of the phalanges of the hand in children. Hand 11 134-143... 

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