Purpose
A sheep study was conducted to test a press-fit technique using microporous pure β–tricalcium
phosphate (β-TCP) dowels for fixation of the anterior cruciate ligament (ACL) graft.
Methods
Microporous (5 μm) cylindrical plugs of β-TCP (diameter, 7 mm; length, 25 mm) with
interconnecting pores were used. The material featured a novel configuration of structure
and surface geometry. Implants were tested by use of press-fit fixation of ACL grafts
with and without bone blocks in 42 sheep over a period of 24 weeks. Biomechanical,
radiologic, histologic, and immunohistochemical evaluations were performed.
Results
In load-to-failure tests at 6, 12, and 24 weeks after surgery, the intra-articular
graft always failed, not the fixation. Grafts showed bony fixation in the tunnel at
6 weeks and primary healing at the junction of the tunnel and joint after 24 weeks.
Tricalcium phosphate was resorbed and simultaneously replaced by bone. Remodeling
was still incomplete at 24 weeks.
Conclusions
In the sheep model microporous β-TCP implants used with press-fit fixation of ACL
grafts permit early functional rehabilitation. After 6 weeks, the graft is fixed by
woven bone or bony integration. Implanted microporous tricalcium phosphate is resorbed
and replaced by bone.
Clinical Relevance
In a sheep model we showed that primary healing of ACL grafts with resorption and
bony replacement of the fixating implant can be achieved by means of press-fit fixation
with pure β-TCP.
Key Words
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Article info
Publication history
Published online: July 27, 2009
Accepted:
February 25,
2009
Received:
October 13,
2008
Footnotes
Supported by Synthes, Oberdorf, Switzerland. The authors report no conflict of interest.
Identification
Copyright
© 2009 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.
