Results of the Anser Clavicle Pin for treatment of Midshaft Clavicle Fractures

Fractures of the clavicle are common, comprising up to 5% of all fractures in
adults [1]. Most clavicle fractures are localized at the level of the
mid-diaphyseal third [2].
Because of the specific sigmoid shaped anatomy and muscle insertions the
majority of these fractures are displaced and/or shortened. These two features
have been found to be poor predictors of outcome concerning non-unions,
persistent posttraumatic symptoms and cosmetics in conservatively treated
mid-shaft clavicle fractures. (MSCF). [3,4,5].
For this reason lately the tendency has been to surgically reduce and fixate
MSCF. Currently the gold standard for these operations is fixation by using a
(angle-stable) plate and screws. This method creates a rigid fixation of the
fracture elements and aims for primary bone healing. It re-establishes and
maintains the normal length and alignment of the clavicle. Patients are able to
quickly start rehabilitating. There have been reports that plate fixation leads
to better rates of union, less mal-unions and increased patient satisfaction in
comparison to conservative therapy [6,7]. The downsides of this procedure are a
large incision with subsequent scarring, neuropathy of the supraclavicular
nerve and increased risk of infection. Hardware irritation necessitating a
secondary operative intervention of 21-80% have been reported [8,9].

Another frequently used technique to reduce and align MSCF is applying
intramedullary devices. These devices are rigid pins (Hagie, Knowles, Rockwood)
(Zimmer Biomet), flexible pins such as titanium elastic nails (TEN)
(Depuy/Synthes) or partially flexible devices such as the CRX Collarbone Pin
(Sonoma Orthopedic Products).
The rigid and partially flexible devices aim for primary bone healing and
require an inside-out open reduction operative technique which means loss of
the fracture hematoma, increased risk of infection and scar over the fracture.
It has produced a variety of results concerning functional outcomes and
complication rates [10-12]. Millet et al. reports nonunion rates up to 8.6%.
All Rockwood Pins are removed during a second intervention [10-12].

The TEN aims for secondary fracture healing by not evacuating the fracture
hematoma with all its bone healing substances. Closed reduction rates are
reported between 29-93% are reported [13,14] but are generally around 50-60%
[15-20]. Good results have been reported using TEN concerning functional
outcomes and nonunion rates [21-23]. TEN is minimally invasive; it requires
smaller incisions. Because of the flexibility of TEN it allows itself to follow
the shape of the clavicle and re-align the fractured clavicle. The downside of
TEN is that they do not protect the MSCF from secondary shortening and
subsequently forming of a, possibly symptomatic, malunion. Secondary shortening
>5mm is reported to be up to 37.5% [17,18,24]. Another negative feature of TEN
is implant migration because the device is not fixated within the clavicle.
This leads to revision rates described between 0-35.3% [16,22]. Hardware
removal, in general, is performed after union in 100% of cases [14,15, 20-24].

The Anser is a novel device for the intramedullary fixation of the fractured
clavicle aiming to combine the pros of both plate and intramedullary devices
into one. Its goal is to reduce the clavicle and preserve its length in a
minimally invasive manner.
An explorative study including 20 patients has been approved by our
institutional review board. An interim analysis after the inclusion of 10
patients shows no intra- or peri-operative complications and adequate callus
formation in all 3 weeks post-operatively. It is hypothesized that due to its
design, in the majority of cases, does not need hardware removal, leading to a
decline in re-operations and costs compared to the current devices used.

The goals of this study are to evaluate the union rate, patient satisfaction
and functional results of the Anser Clavicle Pin in a larger cohort then
approved in the study, Anser; A novel intramedullary device for fixation of
midshaft clavicle fractures. (CMO 2016-2428) Furthermore the indications for
using the Anser Clavicle Pin will be broadened.
The primary outcome measures will be union rate, complication rate and
functional outcome scores.
Secondary outcomes will be closed reduction rate, operative time,
image-intensifier time, hospital stay, incision length, time to radiological
union, pain, re-operation, return to work, health related quality of life and
cosmetic satisfaction.

Prospective case series. Therapeutic study with medical device. A multicenter
trial
with at least 7 Dutch hospitals involved which are Rijnstate Arnhem (RA), UMCG
(UG), Radboudumc (RUMC), Diakonessenhuis Utrecht (DIA) and Zuyderland
Medisch Centrum (ZMC), Haga Ziekenhuis (HAG) and Noordwest Ziekenhuisgroep
(NWZ). UG, RUMC, HAG and NWZ are Level 1 trauma centers. RA, DIA, ZMC are
Level 2 trauma centers. Participating departments will be those of Orthopaedic
and
Trauma Surgery.

The surgical technique for the Anser will be as described in the implant
brochure. Patients are administered prophylactic antibiotics. With a general
anesthetic, the patient is placed in a beach-chair position with the arm draped
freely. The anatomic landmarks of the shoulder will be identified and marked.
The image-intensifier in positioned in such a way that is possible to image the
entire clavicle in two planes. The lateral entry point at the posterior aspect
of the conoid tubercle is identified. A stab incision is made and soft tissues
are spread until the conoid tubercle is in sight. The intramedullary canal
opened using the 4mm Anser Drill Bit and Anser Drill Guide. The Anser Clavicle
Pin is implanted using the Universal Pin Driver or Anser Manual Pin Driver.
Once the Anser Clavicle Pin reaches the fracture site closed reduction is
attempted. The Anser Clavicle Pin is passed through the medial fragment in a
drilling or oscilating manner. The last centimeters towards the
sterno-clavicular joint the Anser Manual Pin Driver is used. Once adequate grip
is obtained the Anser Clavicle Pin is in place. Positioning of the Anser
Clavicle Pin is checked using the image intensifier in two planes. With a
cannulated Anser Tap the lateral cortex is prepared for the Anser Lateral
Fixation Device. Placement of the Anser Lateral Fixation Device. Reduction of
the checked and secured by placement of the Anser Endcap. The Anser Clavicle
Pin is cut flush to the Anser Endcap. Irrigation of the wound followed by
closure of the skin. After coverage of the wound a sling is applied.
Post-operatively the fluoroscopic images will be saved.

During the explorative case series with the Anser we did not identify any
intra- or perioperative complications. Participation in this study can lead to
a decline in complication rates, a higher patient satisfaction than those
reported in literature using current devices and a decline in re-interventions
for hardware removal. One additional outpatient clinic at 1 year
post-operatively is added to the standard of care and two visits (6 weeks and 3
months) will be extended by 10 minutes due to the administration of the outcome
scores.