The frictional engagement of {HEAD ~ each graft ligament} is temporally spaced apart from the frictional engagement of {TAIL ~ at least one other graft ligament} 
The frictional engagement of { HEAD ~ each graft ligament } is temporally spaced apart from the frictional engagement of { TAIL ~ at least one other graft ligament }
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL