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