Purpose: The aim of this study was to compare ultimate load, yield load, stiffness, and displacement
after cyclic loading of a cross-pin technique and an interference screw technique
for the fixation of bone-patellar tendon-bone (BPTB) grafts in anterior cruciate ligament
(ACL) reconstruction. Type of Study: Biomechanical in vitro study. Methods: The devices tested were 2 2.7-mm biodegradable pins (RigidFix; Ethicon, Mitek Division,
Norderstedt, Germany) and biodegradable interference screws (Absolute; Innovasive
Devices, Marlborough, MA). Each device was used for the fixation of 10 8-mm, 9-mm,
or 10-mm sized human BPTB grafts in tunnels drilled in bovine knees. Ultimate load,
yield load, stiffness, and displacement after cyclic loading (1,000 cycles between
50 and 250 N) were then evaluated. Results: All 8-mm grafts that were fixed with cross-pins failed after a mean of 124 cycles
of load. The 9-mm and 10-mm grafts survived the cyclic loading protocol. Yield load
and maximum load of the 10-mm groups (cross-pin and interference screw) were significantly
higher than that of the 9-mm groups. There was no significant difference in maximum
load, yield load, and stiffness between the cross-pin and interference screw fixation
technique for 1 graft size. Conclusions: The biomechanical data suggest that femoral fixation of 9-mm and 10-mm BPTB grafts
using 2.7-mm biodegradable cross-pins leads to primary stability that is comparable
to that of biodegradable interference screws. Fixation of 8-mm BPTB grafts using 2.7-mm
biodegradable cross-pins had poor results. Clinical Relevance: The diameter of the bone block is the limiting factor for the final fixation strength
and the cyclical survival when using cross-pins. We strongly recommend not using this
technique for bone blocks smaller than 9 mm in diameter.
Key Words
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© 2005 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.
