Purpose
To evaluate, using magnetic resonance (MR), the biological efficacy of anchors made
of 30% β-tricalcium phosphate and 70% poly-lactic co-glycolide (PLGA) used for the
repair of Bankart lesions after shoulder instability.
Methods
Twenty consecutive patients who were candidates for surgical treatment for unidirectional,
post-traumatic shoulder instability were treated arthroscopically with anchors made
of 70% PLGA plus 30% β-tricalcium phosphate preloaded with OrthoCord suture (DePuy
Mitek, Raynham, MA). Fifteen of them were evaluated by MR at least 16 months after
the intervention. A second evaluation was performed at least 12 months after the first
evaluation in the patients in whom implanted anchors were still visible at the first
evaluation (n = 5) with a low-intensity signal in all sequences. Two radiologists,
with different amounts of experience (15 and 3 years), separately evaluated the MR
patterns of the trabecular glenoid bone, the walls of the bone tunnel, and the signal
from the anchors. The following parameters were considered in the MR evaluation: integrity
of the tunnel edge (grade 0 to 2), intensity of the signal from the anchor site (grade
1 to 3), and presence of cystic lesions. The normal signal from the glenoid trabecular
bone has been used as the reference parameter. The anchors were considered independent
variables, and thus each one was analyzed individually, even in the same patient.
At the final clinical follow-up, a Rowe questionnaire was filled out for each patient.
Results
Overall, 44 anchors were evaluated (33 anchors at the first follow-up and 11 anchors
at the second follow-up). The mean follow-up period was 28.6 months. With the exception
of 2 patients (10%), none of the patients had any episodes of dislocation, having
satisfactory postoperative results. No cystic lesions were detected by MR imaging.
The interobserver concordance between the 2 radiologists calculated with the Cohen
κ was substantial (κ = 0.780 and κ = 0.791 for integrity of tunnel edge and for intensity
of signal from anchor site, respectively). Both the integrity of the tunnel border
and the intensity of the signal at the site of the anchors that had been implanted
more than 24 months before the evaluation were significantly different from those
of anchors implanted less than 24 months before the evaluation (tunnel border grade
of 0 in 41%, 1 in 50%, and 2 in 9% v 0 in 4.5%, 1 in 50%, and 2 in 45.5% [P = .003]; anchor signal grade of 1 in 41%, 2 in 45.5%, and 3 in 13.5% v 1 in 13.5%, 2 in 41%, and 3 in 45.5% [P = .03]). Analysis of the linear contrasts (analysis of variance) showed a linear
increase in the mean values for time to increased tunnel border grade (grade 0, 22
± 4 months; grade 1, 27 ± 8 months; and grade 2, 29 ± 5 months [P = .02]) and grade of intensity of the signal in the anchor site (grade 1, 24 ± 6
months; grade 2, 26 ± 7 months; and grade 3, 29 ± 7 months [P = .05]).
Conclusions
Anchors made of 30% β-tricalcium phosphate and 70% PLGA showed excellent biological
efficacy, without causing significant cystic lesions, producing gradual changes in
the MR signal that seems to become equivalent to that of the glenoid trabecular bone
at a mean of 29 months after implantation.
Level of Evidence
Level IV, therapeutic case series.
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Article info
Publication history
Published online: December 19, 2013
Accepted:
September 23,
2013
Received:
December 14,
2012
Footnotes
The authors report that they have no conflicts of interest in the authorship and publication of this article.
Identification
Copyright
© 2014 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.
