A device for fixation of the skull (15) to adjacent bones (18A . . . 18E) of the spine (19) comprises a loop (11) of substantially circular form connecting a pair of legs (12) generally perpendicular to the loop, outward kinks (14) being provided adjacent the junction of the loop and legs, whereby, with the loop secured to the skull by wires (16) and the legs secured to the spine by sublaminae wires (20), wires (20', 20") at both sides of the kinks (14) effect fixation of the skull in relation to the adjacent bones of the spine.

This invention relates to a device for fixation of the skull to adjacent 
bones of the spine for stabilisation of the occipito-cervical area, mainly 
to stabilise the base of the skull in relation to the neck, e.g., after 
odontoidectomy with removal of part of the anterior arch of the atlas, 
which decompression is sometimes required in the rheumatoid patient, in 
trauma to the occipito-atlantal joints, for fixation of Jefferson 
fractures (burst fracture of the atlas), after excision of "benign" 
disease of the cervical vertebrae, (i.e., after vertebrectomy for 
chordoma, osteoclastoma and hydatid disease, etc.), or in cervical 
stabilisation for disseminated metastatic disease (i.e., after anterior 
decompression of the neuraxis). 
According to the present invention, a device for fixation of the skull to 
adjacent bones of the spine comprises biocompatible rod-like material 
formed in the slope of a loop of substantially circular form connecting a 
pair of generally parallel legs, with the loop and the legs at their 
junction lying in planes that are generally perpendicular to each other, 
and the legs being provided adjacent that junction with outward kinks, 
whereby, when the loop has been secured to the base of the skull by means 
of wires (or other strands) passing through holes in the skull and the 
legs have been secured to adjacent bones of the spine by sublaminate wires 
(or other strands), wires (or strands) engaged round the legs at both 
sides of the kinks effect fixation of the skull in relation to the 
adjacent bones of the spine. 
The loop may need a superior concavity to fit the base of the skull; this 
concavity can be provided and/or modified by the surgeon by means of 
suitable bending tools, and then the sites of the holes in the skull can 
be marked. Conveniently, the loop is formed in a flat plane and bent by 
the surgeon. The neck should be extended to a normal alignment before 
testing the loop for a good fit. 
A normal cervical lordosis is essential and so the legs are preferably 
formed towards their free ends in a plane curving to the same side as that 
to which the loop extends from the other ends of the legs. The legs may be 
elongated so as to be able to continue the fixation segmentally into the 
dorsal spine if this is indicated as desirable, i.e., for multiple 
metastaces, and appropriate lordosing and/or kyphosing of the legs can be 
carried out by the surgeon by means of suitable bending tools. If 
necessary, the legs may be cut so that the cut ends (which are then the 
free ends) overlie the next most caudal laminae below the fixation. 
Elongated legs may be long enough to extend all the way or most of the way 
along the spine, and may be provided at or (preferably) near their ends 
remote from the loop with a crossbar (e.g., welded thereto) to maintain 
the legs parallel. 
Three similar forms of device in accordance with the invention are 
preferably available, the only difference being the distance (or "waist") 
from the junction between the loop and the legs (or the "occipito-cervical 
angle") to the kinks (or the "hips"). With vertical migration of the 
odontoid peg the "high hips" device fits best, but one or other of the 
other two devices ("mid hips" or "low hips") usually fits all other 
patients. By tightening the sublaminae wires caudal to the "hips" a 
distraction can be obtained if this is indicated as desirable. 
However, alternatively--or in addition--further kinks may be provided along 
the legs, whereby the legs can be secured to bones of the spine by 
sublaminae wires (or other strands) engaged with the further kinks. 
The device (or devices) according to the invention may consist of stainless 
steel or titanium round rod e.g., of 3/16" or 4.7625 mm. diameter, bent to 
shape, but it may be feasible to mould similar devices using fibre 
reinforced plastics material, e.g., carbon-fibre reinforced polyester.

The device 10 shown in FIGS. 1 to 4 is intended for use in fixation of the 
skull to adjacent bones of the spine and comprises biocompatible rod-like 
material formed in a loop 11 of substantially circular form connecting a 
pair of generally parallel legs 12, with the loop and the legs at their 
junction 13 lying in planes that are generally perpendicular to each 
other, and the legs being provided adjacent that junction with outward 
kinks (or "hips") 14 whereby, when the loop 11 has been secured to the 
base of the skull 15 (see FIG. 7) by means of wires 16 through holes 17 in 
the skull and the legs 12 have been secured to adjacent bones 18A....18E 
of the spine 19 by sublaminae wires 20, wires 20' and 20" round the legs 
12 at both sides of the "hips" 14 effect fixation of the skull in relation 
to the adjacent bones of the spine. 
The loop 11 is formed in a flat plane, but can be bent by the surgeon, by 
means of suitable tools, to give it a superior concavity to fit the base 
of the skull 15. The neck should be extended to a normal alignment before 
testing the loop 11 for a good fit. 
The legs 12 are formed towards their free ends 21 in a plane curving to the 
same side as that to which the loop 11 extends from the other ends of the 
legs, and appropriate lordosing and/or kyphosing of the legs can be 
carried out by the surgeon, by means of suitable bending tools, to achieve 
a normal cervical lordosis, which is essential for successful treatment. 
The legs 12 are elongated so as to be able to continue the fixation 
segmentally into the dorsal spine, and, if necessary, the legs are cut so 
that the cut ends (which are then the free ends 21) overlie the next most 
caudal laminae 22 below the fixation. 
FIGS. 5 and 6 illustrate alternative forms of the device 10 in which the 
only difference is the distance (or "waist") 23 from the junction 13 (or 
the "occipito-cervical angle") to the "hips" 14. The device of FIG. 1 is 
the "high hips" device which fits best when there has been vertical 
migration of the odontoid peg 24, see FIG. 7, but bear in mind that this 
illustrates use of the "mid hips" device of FIG. 5, the device of FIG. 6 
being the "low hips" embodiment. 
In FIG. 8 further kinks 14' and 14" are provided in both legs 12, whereby 
the legs can be secured to bones of the spine by sublaminae wires (or 
other strands) engaged with the further kinks. 
The further form of device shown in FIG. 9 has very elongated legs 12 long 
enough to extend all the way or most of the way along the spine, and the 
legs are provided near their ends 25 remote from the loop 11 with a 
crossbar 26 welded thereto to maintain the legs parallel.