Purpose
To analyze the failure mechanism, stiffness, and pullout strength of acetabular knotless
suture anchors.
Methods
Seven suture anchors were tested in high-density (0.48 g/cc) synthetic blocks. The
anchors were implanted perpendicular to the bone block. The anchor's suture(s) were
tied around a loop of 8 high-strength nonabsorbable sutures and pulled in line with
the anchor at a rate of 1 mm/s until failure. The following knotless anchors were
tested: Stryker Knotilus 3.5, Arthrex Pushlock 2.9, Linvatec PopLok 2.8, Linvatec
PopLok 3.3, ArthroCare SpeedLock HIP (3.4-mm), and Smith & Nephew Bioraptor Knotless
2.9. The standard knot tying Smith & Nephew Bioraptor 2.9 mm served as a baseline
for comparison.
Results
Stiffness was highest in the Pushlock, the SpeedLock HIP, and Knotilus. At 1 mm displacement,
the SpeedLock HIP exhibited significantly higher load than all other anchors, excluding
the Pushlock and PopLok 3.3 (P ≤ .012 for all comparisons). Excluding the SpeedLock HIP and Knotilus, the Pushlock
displayed significantly higher load than all other anchors at 2-mm displacement (P ≤ .015 for all comparisons). Maximum load was the highest for the Knotilus and Bioraptor
knotted anchor (P < .001 compared with all other anchors).
Conclusions
All knotless suture anchors used in hip arthroscopy, except for the Knotilus 3.5,
failed by suture pullout from the anchor. The 2 anchors with the highest maximum load,
the Knotilus 3.5 and knotted Bioraptor 2.9, failed by suture failure; however, these
anchors displayed the lowest stiffness and load at 1 mm displacement among all anchors
tested. Stiffness and loads at clinically relevant displacements, not maximum load
alone, may be most important in predicting anchor clinical performance during the
early phases of labral healing.
Clinical Relevance
Knotless suture anchors tend to fail by suture pullout from the anchor, yet the stiffness
of these constructs suggests that minimal displacement of the repair will occur under
physiologic loads.
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Article info
Publication history
Published online: November 22, 2018
Accepted:
July 20,
2018
Received:
April 16,
2017
Footnotes
See commentary on page 77
The study was performed at Stanford University Orthopaedic Surgery Biomechanics Laboratory.
The authors report the following potential conflicts of interest or sources of funding: M.R.S. receives fellowship funding support from Breg, Ossur, Smith & Nephew, and ConMed Linvatec, as well as a research grant from ISAKOS; is an unpaid board member of the International Society of Hip Arthroscopy (ISHA) and the International Society for Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine (ISAKOS); is a consultant for Medacta, Cradle Medical (stock), and Biomimedica (stock options); received paid reimbursement for a lecture by Smith & Nephew and Medacta (not on current topic); has a patent pending for a hip brace and one pending with the university on a hip distraction device; receives book royalties from Elsevier and Wolters Kluwer/Lippincott, shoulder anchor royalties from Howmedica and Stryker, royalties for a hip anchor (Q Fix, suture anchor) from Smith & Nephew, and royalties for a shoulder brace from SJ Ortho; has stock options in Biomimedica and Cradle Medical; and received travel reimbursement from Medacta for a hip meeting. R.M. is a board member of ISHA (no money paid); is a consultant for Smith & Nephew (fees paid to self and institution); and receives personal and institutional grants from Smith & Nephew. All companies provided their anchors free of charge for this study. Full ICMJE author disclosure forms are available for this article online, as supplementary material.
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© 2018 by the Arthroscopy Association of North America
ScienceDirect
Access this article on ScienceDirectLinked Article
- Editorial Commentary: Acetabular Labral Repair—Is A Knotless Anchor Better?ArthroscopyVol. 35Issue 1
- PreviewKnotless anchors have an important role in arthroscopic acetabular labral repair. Different anchors show 2 primary failure modes: suture breakage and suture pullout from the anchor (“eyelet failure”). Knotless anchors show minimal displacement at physiological loads and should perform well for arthroscopic labral repair. Surgeons should consider the suture-passing device size and use a device that creates as small of a labral hole as possible.
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