Purpose
The purpose of this study was to assess the mechanical performance of biocomposite
knotless lateral row anchors based on both anchor design and the direction of pull.
Methods
Two lateral row greater tuberosity insertion sites (anterior and posterior) were identified
in matched pairs of fresh-frozen human cadaveric shoulders DEXA (dual energy X-ray
absorptiometry) scanned to verify comparability. The humeri were stripped of all soft
tissue and 3 different biocomposite knotless lateral row anchors: HEALIX Knotless
BR (DePuy Mitek, Raynham MA), BioComposite PushLock (Arthrex, Naples, FL), and Bio-SwiveLock
(Arthrex). Fifty-two anchors were distributed among the insertion locations and tested
them with either an anatomic or axial pull. A fixed-gauge loop (15 mm) of 2 high-strength
sutures from each anchor was created. After a 10-Nm preload, anchors were cycled from
10 to 45 Nm at 0.5 Hz for 200 cycles and tested to failure at 4.23 mm/second. The
load to reach 3 mm and 5 mm displacement, ultimate failure load, displacement at ultimate
failure, and failure mode were recorded.
Results
Threaded anchors (Bio-SwiveLock, P = .03; HEALIX Knotless, P = .014) showed less displacement with anatomic testing than did the nonthreaded anchor
(BioComposite PushLock), and the HEALIX Knotless showed less overall displacement
than did the other 2 anchors. The Bio-SwiveLock exhibited greater failure loads than
did the other 2 anchors (P < .05). Comparison of axial and anatomic loading showed no maximum load differences
for all anchors as a whole (P = .1084). Yet, anatomic pulling produced higher failure loads than did axial pulling
for the Bio-SwiveLock but not for the BioComposite PushLock or the HEALIX Knotless.
The nonthreaded anchor (BioComposite PushLock) displayed lower failure loads than
did both threaded anchors with axial pulling.
Conclusions
Threaded biocomposite anchors (HEALIX Knotless BR and Bio-SwiveLock) show less anatomic
loading displacement and higher axial failure loads than do the nonthreaded (BioComposite
PushLock) anchor. The HEALIX Knotless BR anchor showed less displacement than did
the BioComposite PushLock and Bio-SwiveLock anchors. Neither axial nor anatomic loading
had an effect on overall anchor displacement.
Clinical Relevance
Because of the strength profiles exhibited, this study supports the use of biocomposite
anchors, which have definite advantages over polyetheretherketone (PEEK) and metal
products. However, the nonthreaded BioComposite PushLock anchor cannot be recommended.
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Article info
Publication history
Published online: April 11, 2013
Accepted:
February 4,
2013
Received:
February 21,
2012
Footnotes
The authors report the following potential conflict of interest or source of funding in relation to this article: all authors have received consulting fees/honoraria from DePuy Mitek, Ryanham, MA. Study supported by a grant from DePuy Mitek.
Identification
Copyright
© 2013 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.
