Preferably, the invention relates to {TAIL ~ a device} wherein {HEAD ~ the distraction} screw is replaceable 
Preferably , the invention relates to { TAIL ~ a device } wherein { HEAD ~ the distraction } screw is replaceable
OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH