1. Evolution of hook design for fixation of the titanium Greenfield filter 
Lazar J. Greenfield, MD, Kyung J. Cho, MD, John R. Tauscher, MD 
Journal of Vascular Surgery 
Volume 12, Issue 3, Pages (September 1990)
DOI: / (90)
Copyright © 1990 Society for Vascular Surgery and International Society for Cardiovascular Surgery, North American Chapter Terms and Conditions

2. Fig. 1
Comparison of the stainless steel standard Greenfield filter (left) with the titanium model of the Greenfield filter (right).
Journal of Vascular Surgery  , DOI: ( / (90) )
Copyright © 1990 Society for Vascular Surgery and International Society for Cardiovascular Surgery, North American Chapter Terms and Conditions

3. Fig. 2
A, Modification (type I) of the titanium Greenfield filter reducing the base diameter to 33 mm and changing hook angle from 38 degrees to 22 degrees. B, Type II modification of the titanium Greenfield filter demonstrating a 38 mm base diameter, 22 degree hook angle, and absence of limb flare. C, Type IV modification of the titanium Greenfield filter demonstrating an expanded hook angle to 80 degrees, 38 mm base diameter, and flared limbs. D, Type VI modification of the titanium Greenfield filter demonstrating a recurved hook design with a twist to 80 degrees, 38 mm base diameter, and flared limbs.
Journal of Vascular Surgery  , DOI: ( / (90) )
Copyright © 1990 Society for Vascular Surgery and International Society for Cardiovascular Surgery, North American Chapter Terms and Conditions

4. Fig. 3
Anteroposterior view of control titanium Greenfield filter (left, below) and type I modification (left, above) 4 weeks after insertion with obvious slippage, tilting, and suspected penetration of the vena cava seen best on the lateral view (right). At autopsy the distracted limb was not penetrating but found within a renal vein.
Journal of Vascular Surgery  , DOI: ( / (90) )
Copyright © 1990 Society for Vascular Surgery and International Society for Cardiovascular Surgery, North American Chapter Terms and Conditions

5. Fig. 4
Example of progressive increase in base diameter from the time of insertion (left) to termination at 4 weeks (right) of both type II (below) and control titanium Greenfield filters (above). Penetration of the caval wall was confirmed at autopsy.
Journal of Vascular Surgery  , DOI: ( / (90) )
Copyright © 1990 Society for Vascular Surgery and International Society for Cardiovascular Surgery, North American Chapter Terms and Conditions

6. Fig. 5
Sequential radiographs at 2-week intervals from the time of insertion (left) to termination at 4 weeks after cavogram (right). The type IV titanium Greenfield filter (above) shows broadening of the base at 2 weeks (center) and penetration of the cava was confirmed at autopsy. The type VI titanium Greenfield filter (below) shows minimal expansion and migration with no penetration at autopsy.
Journal of Vascular Surgery  , DOI: ( / (90) )
Copyright © 1990 Society for Vascular Surgery and International Society for Cardiovascular Surgery, North American Chapter Terms and Conditions

7. Fig. 6
A, Contrast anteroposterior cavogram (left) and lateral view (right) after experimental embolism into the type IV filter outlined by contrast medium flowing around it (arrows). B, After 4 weeks, contrast venacavogram shows residual of thrombus on both anteroposterior (left) and lateral views (right). Abdomen shows retained stool but thrombus is outlined by contrast medium (arrows).
Journal of Vascular Surgery  , DOI: ( / (90) )
Copyright © 1990 Society for Vascular Surgery and International Society for Cardiovascular Surgery, North American Chapter Terms and Conditions