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neurosurgery, maxillofacial surgery, and orthopedic surgery.7
The ability of this technology to enhance osseous integration
through an amorphous liquid phase that molds a positive form
fit with cancellous bone, while minimizing cortical defects due
to a smaller diameter, has made this system an attractive option
to orthopedic surgeons.7,10
In a cadaveric study, ultrasound-assisted suture anchors
demonstrated a similar pullout strength and less system displacement when compared with a benchmark bioabsorbable
anchor system.7 However, the failure and complication
rates of ultrasound-assisted bioabsorbable anchors have
never been demonstrated in a clinical setting. Stryker
(Kalamazoo, MI) has recently developed an ultrasoundassisted suture anchor system, SonicAnchor, which uses
ultrasound technology to liquefy the tip of the anchor and
allow the bioresorbable polymer poly(l-lactide-co-d,l-lactide) (PLDLLA) to interdigitate and integrate into the surrounding cancellous bone. The anchor itself is 2.5 mm,
allowing for a minimal footprint and risk of cortical defect.17
With the increasing popularity of bioabsorbable suture
anchors, and specifically ultrasound-assisted systems, we
believe it was imperative to ensure the safety of these devices
in a clinical setting. The primary purpose of this study was to
assess the safety of this suture anchor by examining complication rates in foot and ankle procedures. A secondary goal
was to determine the efficacy by evaluating the clinical outcomes of soft tissue surgeries using this anchor system.

Methods
This study was approved by the senior author's (SGP)
Institutional Review Board. A retrospective analysis was
performed on all patients that were surgically treated by the
primary investigator (SGP) using the Stryker SonicAnchor
system between the dates of May 26, 2016, and February
20, 2018. We included all patients who underwent a surgery
to their foot or ankle involving the use of this anchor system
with at least 24 months of follow-up. Exclusion criteria
included insufficient follow-up or data. Preoperative data
gathered from the patient charts included age at time of surgery, sex, height, weight, primary indication for surgery,
tobacco use, comorbidities, VAS score, and FAOS.
Postoperative data included adverse events documented,
final VAS score, and final FAOS. The primary endpoint of
the study was to evaluate adverse event rates following
operative treatment with this device, and the secondary endpoint was to evaluate the clinical outcome of these patients
using the Foot and Ankle Outcome Score (FAOS) and
visual analog scale (VAS) score. A paired sample t test was
used to detect any significance between preoperative and
postoperative clinical scores with alpha set to 0.05. We
divided adverse events into minor complications and major
complications depending on whether a return to the operating room or long-term morbidity occurred.

Foot & Ankle International 41(9)
Table 1. Types of Operative Cases Analyzed.
Type of case
Lateral ligament reconstruction
Insertional Achilles repair
Lateral ligament reconstruction with total
ankle replacement
Plantar plate repair
Lateral ligament reconstruction and
deltoid ligament repair
Peroneus brevis reattachment
Tibialis posterior tendon reattachment
after accessory navicular excision
Deltoid ligament repair

Number of cases
19
15
6
3
2
2
2
1

We initially identified 118 patients who underwent surgery in the selected time period with the anchor. Of these
patients, 23 were excluded due to insufficient follow-up
data. Of the remaining 95 patients, 45 were excluded
because the length of follow-up was less than 24 months.
Therefore, we identified 50 subjects who met inclusion and
exclusion criteria. The mean age of the patients at the time
of surgery was 51 (range, 15-82) years. The average body
mass index (BMI) was 30.5 (range, 18.4-50.2) kg/m2. There
were 22 males and 28 females. The average follow-up was
33.4 months. There were 12 former smokers, 3 current
smokers, and 35 never smokers. Four patients had a diagnosis of diabetes mellitus. One patient had a diagnosis of
osteoporosis. There were 19 procedures performed for lateral ligament reconstruction, 15 procedures for insertional
Achilles repair, 6 procedures for lateral ligament repair in
conjunction with a total ankle arthroplasty, 3 procedures for
plantar plate repair, 2 procedures for concurrent lateral ligament and deltoid ligament repair, 2 procedures for peroneus
brevis reattachment, 2 Kidner procedures, and 1 isolated
deltoid repair (Table 1).
In all cases, the suture anchor was utilized according to
standard technique.18 A start-up test was performed in all
cases to ensure proper functioning of the equipment. Next,
the bone was prepared with the provided drill (Figure 1).
The anchor was mounted onto the handpiece tip with the
nonabsorbable suture pulled taut inside the recess of the
anchor. The anchor was placed into the drill hole and axial
force was applied while the suture strands were pulled longitudinally, and the footswitch was held down for approximately 5 seconds until the audible beeping signal was heard
from the ultrasound generator. The strands were then pulled
to ensure secure fixation, which was present in all cases.

Results
Of these 50 procedures, there were 8 complications (Table 2).
Five were cases of superficial soft tissue infections or skin
irritation that resolved with wound care and/or 2 weeks of

Foot & Ankle International - September 2020

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