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Core Set of Radiographic Parameters for Shoulder
Arthroplasty Monitoring
Criteria Defined by an International Delphi Consensus Process
Holger Durchholz, MD, Bj¨
orn Salomonsson, MD, Philipp Moroder, MD, Simon Lambert, FRCS(Ed&Orth), Richard Page, FRACS,
and Laurent Audig´
e, PhD, on behalf of the Shoulder Arthroplasty (SA) Monitoring Steering Group*
Background: Some unfavorable local events following shoulder arthroplasty occur without the patient experiencing
symptoms and yet may be detected on diagnostic imaging, thereby serving as indicators of complications that may require
revision. Our aim was to create a standardized protocol for an image-based monitoring process for assessing patients who
are asymptomatic following shoulder arthroplasty.
Methods: A Delphi exercise was implemented with the participation of an international panel of experienced
shoulder surgeons. On the basis of expert opinion from a core steering group, an initial list of imaging parameters for
shoulder arthroplasty monitoring of asymptomatic patients was developed and reviewed by panel members. The
most appropriate imaging modality was identified. Between each survey, all feedback was considered in order to
revise the proposed core set with its definitions and specifications. Consensus was reached upon a two-thirds
agreement.
Results: Three online surveys were administered, with 98 surgeons responding to the first and/or the second survey. The
response rate for the final survey was 74%. Final parameter definitions were organized in 7 categories (implant migration,
radiolucency around implant and implant loosening, signs of shoulder displacement, bone resorption and formation, wear
of implant articular surfaces, fractures around the implant, and implant breakage and disassembly) and approved with
85% to 100% agreement. Seventy-eight percent of the panel members agreed on a minimum radiographic imaging
schedule: standard anteroposterior and axial (alternatively, Y) views made within 6 weeks after implantation and between
3 and 6 months as well as at 12 months post-surgery.
Conclusions: Our work presents a monitoring tool developed with international consensus for the assessment of
asymptomatic patients after shoulder arthroplasty and including a structured core set of radiographic parameters. Clinical
application and scientific evaluation of the monitoring process are needed.
Clinical Relevance: This represents a major step toward the standardization of shoulder arthroplasty radiographic
monitoring for routine quality controls and research investigations.
Image-based monitoring plays an important role in
decision-making processes associated with shoulder
arthroplasty and long-term prosthesis survival
1,2
. Shoulder
arthroplasty is one of the most successful procedures for
treating end-stage arthritis of the glenohumeral joint
3
,
among other indications, including rotator cuff arthropathy,
trauma, osteonecrosis, and rheumatoid arthritis
4
. However,
some shoulder arthroplasties fail and implant revision is
required. The reasons for failure are multifactorial
5
and
generally caused by an intrinsic factor, or a combination of
factors, associated with the soft tissue, bone, and/or
implant
6
. Common types of failure, including loosening,
bone loss, or instability, can be diagnosed using standard
radiographs.
*A list of the Shoulder Arthroplasty (SA) Monitoring Steering Group members is included as a note at the end of the article.
Disclosure: The authors indicated that no external funding was received for any aspect of this work. On the Disclosure of Potential Conflicts of Interest
forms, which are provided with the online version of the arti cle, one or more of the authors checked “yes”to indicate that the author had a relevant financial
relationship in the biomedical arena outside the submitted work and “yes”to indicate that the author had a patent and/or copyright, planned, pending, or
issued, broadly relevant to this work (http://links.lww.com/JBJSOA/A118).
Copyright Ó2019 The Authors. Published by The Journal of Bone and Joint Surgery, Incorporated. All rights reserved. This is an open-access article
distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to
download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the
journal.
JBJS Open Access d2019:e0025. http://dx.doi.org/10.2106/JBJS.OA.19.00025 openaccess.jbjs.org 1
The systematic assessment of radiographs for catego-
rizing shoulder arthroplasty failure type is complicated by a
lack of consensus on the most relevant radiographic param-
eters. Furthermore, a clear and accepted minimum radio-
graphic follow-up procedure including the types and quality
of radiographic views and a time schedule is missing. A
minimum radiographic monitoring regimen is warranted for
assessing the progression of parameters in shoulder arthro-
plasty and should be applicable to all types of shoulder
arthroplasty.
This project was implemented to develop a standardized
protocol for an image-based monitoring process in the assess-
ment of patients who are asymptomatic following shoulder
arthroplasty, including a defined core set of radiographic
parameters as well as minimum requirements governing the
radiograph type, views, and schedule. A structured assessment
tool was achieved by consensus with the participation of an
international panel of experienced shoulder surgeons.
Materials and Methods
Delphi Process
For the identification of a core set of imaging parameters for
shoulder arthroplasty monitoring, we applied a methodo-
logical process
7
used for core outcome set (COS) development.
Following a systematic literature review of terms and defini-
tions of shoulder arthroplasty complications, a Delphi tech-
nique
8
was implemented after the selection of a consensus
panel of experienced surgeons (see Appendix File 1). In short,
supported by a steering group with worldwide representation,
we conducted 3 successive online surveys using REDCap
(Research Electronic Data Capture)
9
. In the first online sur-
vey, we asked participants about routinely used imaging
technique(s) and timing for monitoring shoulder arthroplasty
as well as relevant imaging parameters that may be considered
(see Appendix File 2). From the initial responses, the steering
group agreed that shoulder arthroplasty monitoring would be
performed using radiographs. A second survey was prepared
considering 6 groups of radiographic parameters (see Appen-
dix File 3) as well as 4 additional parameters proposed by the
panel members. A minimum set of radiographic views was
suggested to be made within the first week and at 3 and
12 months after implantation. Responses from the second
survey were reviewed, and amendments were implemented in a
revised proposal that was presented to consensus panel mem-
bers in a third survey (see see Appendix File 4).
Data Analysis and Final Adjudication
Survey data were transferred to Intercooled Stata version 14
(StataCorp) for standard descriptive analyses. Consensus was
achieved upon a two-thirds agreement among the respondents.
Final amendments and decisions were made by the steering
committee following a review of all reported comments.
Results
Of 182 surgeons who were invited to participate, 98 re-
sponded to the first and/or the second survey (Table I;
see also Appendix File 5). The response rate to the third and
final survey was 74%. The panel had international represen-
tation: 74 (76%) of the surgeons were from 13 countries in
Europe, 13 were from North America (U.S. and Canada), and
11 other members were from Chile, Brazil, Israel, and
Australia.
In the initial survey, 88 respondents unanimously sup-
ported radiographs as the standard routine imaging technique
for monitoring shoulder status in asymptomatic patients fol-
lowing shoulder arthroplasty (see Appendix File 6). A pre-
liminary list of imaging parameters was agreed on, and
respondents provided numerous comments and suggestions
for definitions, allowing for the drafting of a consolidated
proposal. The parameters “arthritis,”“stress shielding,”and
“integrity of the rotator cuff ”were excluded from further
consideration. Suggested minimum time points for systematic
image monitoring within and after the first 5 years were het-
erogeneous. Radiographic monitoring at 3, 6, and 12 months
was supported by 55%, 39%, and 78% of 88 respondents,
respectively; 64% agreed on a 5-year check (Table II).
Proposed parameter definitions and their specifications
were widely accepted by >90% of the 68 participants in the
TABLE I Consensus Panel Skills*
Experience†
Total1-5 yr >5-10 yr >10-20 yr >20 yr
Average no. of SAs/yr‡
1-20 —45312
>20-50 1 7 14 15 37
>50-100 —3161534
>100 —17715
Total 1 15 42 40 98
*The values are given as the number of surgeon respondents. †Survey question: “How many years of surgical experience do you have in
orthopaedics?”‡Survey question: “On average, how many shoulder arthroplasties (SAs) do you perform annually?”
Core Set of Radiographic Parameters for Shoulder Arthroplasty Monitoring
JBJS Open Access d2019:e0025. openaccess.jbjs.org 2
second survey (see Appendix File 7). Consensus agreement was
reached for additional parameters: osteochondral glenoid
erosion in hemiarthroplasty (70% agreement), fractures around
the implant (humeral or scapular side, 83%), and implant
breakage and dissociation (87%). Consensus (75% agreement)
was also attained regarding our proposed minimum radiographic
view set and schedule, but comments suggested that the 3-month
time point be extended to 6 months to offer some flexibility
without losing relevance.
During the third survey, 85% to 100% of the respondents
agreed to the definitions and specifications of the final radio-
graphic parameters organized into 7 groups (Table III; see also
Appendix File 8). The minimum radiographic view set and
schedule for monitoring asymptomatic patients following
shoulder arthroplasty included a true anteroposterior view in
0°of abduction and neutral position, and an axillary view in
90°of abduction or a Y-view made within 6 weeks, between 3
and 6 months, and at 12 months post-surgery, which was
approved with 78% agreement among 64 respondents. Upon
final adjudication of all survey-related comments, some minor
amendments were made to the parameter set; for example, we
changed the term “signs of shoulder instability”to “signs of
shoulder joint displacement.”
Discussion
Using a Delphi technique
8
, we achieved consensus among an
expert panel of specialized shoulder surgeons regarding a
standardized core set of parameters for radiographic moni-
toring after shoulder arthroplasty. The present core set is in-
tended for monitoring asymptomatic patients. This work can
be applied for the routine monitoring of all types of shoulder
prostheses in clinical practice as well as for registries providing
Level-IV data
10
, with a standardized overview regarding the
most relevant problems after shoulder arthroplasty. Additional
parameters and monitoring time points may be considered,
notably in the context of scientific studies requiring more in-
depth investigations.
Implant Migration
Implant migration is relevant in shoulder arthroplasty moni-
toring, mainly as an indicator of potential implant loosening,
which may require subsequent and extended monitoring.
However, subtle implant migration without any clinical
symptom or restriction of function is not necessarily clinically
relevant. Implant migration, whether it occurs in the form of
subsidence, tilt, or shift, occurs over a period of time between
radiographic examinations. It is not malposition noted directly
post-surgery.
Subsequent radiographic examination may produce differ-
ent patterns of implant migration. Early migration during the first
months followed by a stable situation is normal for some implants;
uncemented implants are reported to settle before fixation is sta-
ble
11
. Continuous migration on subsequent examinations, how-
ever, is considered the result of an implant without stable fixation
and a risk factor for the progression to loosening
12,13
.
The current and most precise method of detecting implant
migration involves radiostereometric analysis
14,15
.Onradio-
graphs, the ability to detect migration ishighly dependent on the
accuracy of measurement and the quality of radiographic
images. The panel suggested that migration should be >5 mm in
order to be considered “definite.”Atiltof>10°could also be
considered migration if radiographs are made in the same plane
as in previous views, although the amount of both implant and
humeral rotation is generally difficult to assess. Our definition of
“implant migration”provides the option to report “definite
migration”when an undisputed, noticeable change is detected.
Additional examinations should otherwise be considered.
Radiolucency Around the Implant and Implant Loosening
Radiolucent lines at the bone-implant, bone-cement, or cement-
implant interface are a risk factor for implant loosening
16-18
.
Many systems for documenting radiolucent lines exist
19
and are adapted to consider varying implant designs. The
presence of radiolucent lines on the humeral side is classically
defined by zones
16,20,21
, depending on the stem length or fix-
ation technique; a similar organization exists for glenoid
TABLE II Suggested Time Points for Radiographic Monitoring
After Shoulder Arthroplasty
Time Point No. of Respondents %
£5yr
Never 0 —
3mo 48 55
6mo 34 39
12 mo 69 78
2yr 46 52
3yr 24 27
4yr 14 16
5yr 56 64
Other time points* 5 6
>5 yr
Never 8 9
Every year 9 11
Every 2 yr 23 27
Every 3 yr 7 8
Every 5 yr 28 33
Every 10 yr 1 1
Other frequency†911
*Suggestions up to 5 years included: “immediate post-surgery
images”;“whenever patients have new symptoms related to the
joint or if symptoms change”; and “1 year, then if all is well, more
than 2 years—I wonder if it could be next left until 5 years.”
†Suggestions after 5 years included: “only if clinically indicated or
the patient presents with a problem”;“4, 7, 10 years, then every 2”;
“on development of new symptoms”;“whenever patients have
symptoms related to the joint or if symptoms change”;“only when
symptomatic, as decision for intervention not dictated by radio-
logical appearances”;“if patient has symptom about 7 to 8 years, I
think it should be every 2 years and then if anything untoward is
seen, then more frequently”; and “at 10 then every 10 [years]”.
Core Set of Radiographic Parameters for Shoulder Arthroplasty Monitoring
JBJS Open Access d2019:e0025. openaccess.jbjs.org 3
TABLE III Definitions and Specifications of Postoperative Radiographic Monitoring Parameters
Parameters Definitions and Specifications Agreement
Implant migration
(subsidence, tilt, shift)
Implant migration is a noticeable change in the position of the implant, relative to
the bone it is intended to be fixed to (either cemented or uncemented). Implant
migration is documented separately for the humeral and glenoid components
94% (65/69)
- Subsidence: migration of the implant along a linear axis compared with the
immediate post-implantation position. Documented as 1 of 3 classes:
None = no sign of subsidence
Suspicion = subsidence is suspected but with no more than 5 mm of migration
Definite = subsidence is noted with >5 mm of migration
- Tilt: migration of the implant resulting in an angulation of its main axis compared
with the immediate post-implantation position. Documented as 1 of 3 classes:
None = no sign of tilt
Suspicion = tilt is suspected but with no more than 10°of angulation
Definite = tilt is noted with >10°of angulation
- Shift: migration as a combination of subsidence and tilt. Shift is suspected when
both subsidence and tilt are suspected or 1 is suspected and the other is definite.
Shift is definite when both subsidence and tilt are definite
Radiolucency around
the implant and implant
loosening
Radiolucency relates to the occurrence or observation of radiolucent lines (RLLs)
at the bone-implant, bone-cement, or cement-implant interface. RLLs are
documented according to their presence or absence, location, and thickness,
separately for the humeral and glenoid components. The humeral component is
further divided into metaphysis and diaphysis according to the surgical neck of the
humerus. Within each of these locations (as appropriate for various prosthesis
types), the severity of RLL occurrence is graded as follows:
99% (67/68)
Grade 0 = none (no clear sign of RLLs)
Grade 1 = incomplete RLLs (radiolucency not all around the implant)
a. no line reaching 1.5 mm in width
b. at least 1 RLL reaching ‡1.5 mm in width
Grade 2 = complete radiolucency around the implant
a. not reaching 1.5 mm in width
b. reaching ‡1.5 mm in width (loosening)
Implant loosening is considered when respective components are identified with
Grade-2b lucency or a shift in position (see above parameter) between
postoperative radiographs (implant at risk of failure on the basis of radiographic
outcome)
Signs of shoulder joint
displacement
Shoulder joint displacement refers to a loss of alignment of the articulating surface
of the humeral component with the articulating surface of its joint partner; not
dependent on positioning of the arm
85% (57/67)
- Subluxation: eccentric misalignment of the articulating surfaces with residual
contact visible on standard radiographs
- Dislocation: complete loss of contact of the articulating surfaces visible on
standard radiographs
When present, the direction of subluxation or dislocation is noted on the
anteroposterior view (superior/inferior) as well as the axillary view or Y-view
(anterior/posterior)
Bone resorption and
formation
Bone resorption: the progressive disappearance of bone from the humerus and/or
scapula following shoulder arthroplasty (SA) when compared with the immediate
postoperative condition. Bone resorption includes scapular notching and
osteochondral erosions (described below)
100% (65/65)
Bone formation: the progressive apposition of bone on or in the humerus and/or
scapula following SA when compared with the immediate postoperative condition,
more than that required for stable integration of the prosthesis
continued
Core Set of Radiographic Parameters for Shoulder Arthroplasty Monitoring
JBJS Open Access d2019:e0025. openaccess.jbjs.org 4
TABLE III (continued)
Parameters Definitions and Specifications Agreement
- Orthotopic bone formation (ossification): bone formation within the confines of the
bone including the periosteum; bone is formed within tissue that is destined to be or
become bone under normal healing or loading conditions
- Heterotopic bone formation (ossification): a subset of excess bone formation
within or between tissues that is not destined to become bone under normal healing
or loading conditions
Specifications include a bone region-based description of periprosthetic
occurrence/extent of bone resorption/formation:
- Humeral side: further divided into metaphysis and diaphysis according to the
surgical neck of the humerus. When bone resorption is located proximal to the
surgical neck, the involvement of the calcar region and/or the tuberosities is
documented
- Glenoid side (without further division)
Heterotopic bone formation is graded according to a modified Brooker
classification
28
:
Grade 1 = islands of bone within the soft tissues around the shoulder
Grade 2 = bone spurs from the proximal humerus or scapula, leaving at least 1 cm
between opposing bone surfaces
Grade 3 = bone spurs from the proximal humerus or scapula, reducing the space
between opposing bone surfaces to <1 cm
Grade 4 = apparent osseous ankylosis of the shoulder
Scapular notching (specific to reverse SA): bone resorption with disruption of the
normal contour (= notch) near the glenoid base plate. Graded according to the Nerot-
Sirveaux classification
43,44
:
Grade 1 = notch limited to the scapular pillar
Grade 2 = notch reaching the inferior screw of the base plate
Grade 3 = notch extending beyond the inferior screw of the base plate
Grade 4 = notch reaching the central peg of the base plate
Osteochondral erosions (as another form of bone resorption): abrasion of bone
and/or cartilage caused by friction with a prosthetic component
- Glenoid erosion (only for hemiarthroplasty)
Eccentric: occurrence of localized glenoid rim erosion
Concentric: humeral head centered without localized glenoid rim erosion
- Erosion of the acromion (only for anatomical hemi- and total arthroplasty): concave
deformity of the acromion undersurface (“acetabularization”)
Wear of the implant
articular surfaces
Damage, erosion, or loss of the articular surface material over time, identified by a
reduction of joint space observed on serial radiographs
97% (62/64)
- Eccentric: the wear location is noted on the anteroposterior view (superior/inferior)
as well as the axillary view or Y-view (anterior/posterior)
- Concentric
Fractures around the
implant
Humeral fracture: 98% (63/64)*
- Tubercula
- Subcapital, at the surgical neck (stemless prosthesis)
- Diaphysis spiral/transverse (stemmed shaft prosthesis)
- Distal (below the shaft)
Scapular fracture
31
:
- Body
- Processes (spine, acromion, coracoid)
continued
Core Set of Radiographic Parameters for Shoulder Arthroplasty Monitoring
JBJS Open Access d2019:e0025. openaccess.jbjs.org 5
components
16,22,23
. The differentiation in systems makes it very
difficult to compare several designs and studies. Our suggested
grading system for radiolucency was simplified for applicability
to all shoulder arthroplasty types, fixation techniques, and
glenoid components. The presence of radiolucent lines or
actual asymptomatic implant loosening does not always lead
to a shoulder functional deficit
2,12,24,25
. For clinical practice, we
believe that there is no need for a more detailed description of
radiolucent lines. In symptomatic cases of radiolucent lines or
in a research setting, other imaging examinations, such as
computed tomography (CT) scanning
2
, may be performed.
Signs of Shoulder Joint Displacement
Shoulder joint displacement can vary in terms of type and
severity, and yet a distinction is made between misalignment
with residual contact of the articulating surfaces (subluxation)
and a complete loss of contact (dislocation) of these surfaces.
While dislocation can easily be detected on standard radio-
graphs, subluxation can be more difficult to identify, depending
on its severity. Radiographic signs of displacement are docu-
mented as a proxy for the occurrence of shoulder instability.
Instability in anatomical or reverse shoulder arthroplasty is not
uncommon
26,27
, although the presence or absence of symptoms
is dependent on the chronicity and the cause of instability. For
example, while patients with acute dislocation occurring
within a few weeks after shoulder arthroplasty are likely to
demonstrate symptoms, patients with some chronic instability
caused by soft-tissue deficiency may remain asymptomatic, and
the instability is suspected only from signs of joint displacement
on postoperative radiographs, requiring further investigation.
The monitoring set of radiographs is appropriate for
identifying possible static instability. The misalignment of
shoulder arthroplasty components (displacement) is perma-
nent, regardless of arm position. In contrast, dynamic insta-
bility refers to a condition in which the components are either
aligned or misaligned depending on the arm position; this can
be detected using functional imaging by means of fluoroscopy
or a series of radiographs with the arm in varying positions.
Dynamic instability is therefore an unfavorable event that
cannot be monitored through signs of joint displacement when
using a minimum set of radiographs required for all patients.
Bone Resorption and Formation
Bone resorption and formation may be considered physiological
or non-physiological events. An appropriate physiological
response may result as a direct effect of loading through the
prosthesis or as an indirect effect modulated through usual
loading of the related soft tissues. For instance, homotopic bone
formation occurs around humeral prostheses following shoulder
arthroplasty with uncemented components as a response (via
callus) to microfracturing of trabecular bone during implanta-
tion. In contrast, an inappropriate bone response may be trig-
gered, for example, following capsular release from the humerus.
Bone formation in excess to that required for stable integration
of a shoulder arthroplasty prosthesis is usually undesirable.
Resorption, mostly of cortical bone or the periosteal
surface, manifests on radiographs as the absence or hypoden-
sity of bone previously present or of normal quality. Bone
formation manifests as the appearance of bone that was pre-
viously absent. Observations of either resorption or formation
should be interpreted with caution, notably with regard to the
indication for shoulder arthroplasty as well as the implant
design used: different periprosthetic bone behaviors and pat-
terns of bone resorption are exhibited following shoulder
arthroplasty performed with uncemented compared with ce-
mented implants. The classification of heterotopic bone for-
mation based on that used for the lower extremity
28
has been
applied to shoulder arthroplasty, whether cemented or un-
cemented, but requires further validation using radiographs.
Implant Articular-Surface Wear
Implant wear is defined as the damage, erosion, or loss of
surface material of an implant over time, usually due to fric-
tion. Implant wear creates biologically active particles gener-
ating an inflammatory response that may result in loss of
implant fixation, detected indirectly as bone resorption or
implant migration. True wear without lysis is more difficult to
detect and requires well-aligned serial radiographs made in the
same plane to visualize articular joint-space loss. Monitoring
for wear enables the early identification of a prosthesis at risk
for loosening and (potentially catastrophic) failure or peri-
prosthetic fracture that might increase the complexity of revi-
sion surgery.
TABLE III (continued)
Parameters Definitions and Specifications Agreement
- Glenoid neck
- Articular (glenoid rim, fossa)
Implant breakage and
disassembly
Implant breakage: ‡1 part of the prosthesis is broken
Implant disassembly: noticeable change of the relative position of the various parts
of a humeral or glenoid implant component
Humeral side and scapular side
*This percentage of agreement applies to both parameter groups “Fractures around the implant”and “Implant breakage and disassembly.”
Core Set of Radiographic Parameters for Shoulder Arthroplasty Monitoring
JBJS Open Access d2019:e0025. openaccess.jbjs.org 6
Fractures Around the Implant
Patients with implant fractures following shoulder arthroplasty
usually present with symptoms, but in some cases, the patient
can be, or may become, asymptomatic
29
. The consensus panel
agreed almost unanimously (98%) to include fractures around
the implant in the radiographic monitoring set. Classification
systems for periprosthetic fractures have been developed and
included in treatment algorithms
30
that are beyond the aim of
this monitoring process to primarily document the occurrence
of fractures and their localization. For our purposes, we
adapted a proposed system for scapular fractures
31
.
Implant Breakage and Disassembly
Implant breakage and, especially, disassembly has been
described for several implant designs
32-35
. It was therefore
essential to include this parameter in the radiographic moni-
toring set for both humeral and scapular sides, even if most of
these events would be accompanied by symptoms.
Radiographic View Set and Schedule
Adequate imaging is necessary for an accurate preoperative and
postoperative assessment of shoulder arthroplasty
1
. For post-
operative imaging, radiographs seem to be the standard. Post-
operative CT has a greater ability to detect radiolucent lines
36,37
than do radiographs
4
. Magnetic resonance imaging (MRI), with
suitable software, or ultrasound would be necessary if the
integrity of soft tissue such as the rotator cuff needed exami-
nation in symptomatic patients. However, for this postoperative
monitoring set for patients who are asymptomatic following
shoulder arthroplasty, it became clear after our initial survey that
radiographs alone would be appropriate at this current time.
A minimum radiographic view set of at least 2 orthogonal
views were widely accepted for monitoring. Shoulder arthro-
plasty was considered best assessed postoperatively with anter-
oposterior and axial views of the shoulder
6
or with true
anteroposterior views in internal and external rotation and an
axial view
4
. These views allow the verification of correct implant
positioning and provide reference images for prescribing the
subsequent follow-up for the patient: any new entity appearing
on follow-up images can be compared with previous images
2
.
We acknowledge that some patients may not tolerate holding
their shoulder in the required positions to produce the necessary
views in the initial postoperative period
6
; therefore, a Y-view
(lateral projection) isan accepted alternative. Other radiographic
views are considered in a diagnostic context.
There were considerable debate and divergent opinions
regarding the monitoring schedule. Our recommendation is
to obtain the first set of radiographs within the first 6 weeks
after implantation, especially considering the difficulty in
obtaining a reproducible series of radiographs shortly after
surgery because of pain and the need to protect the re-
constructed soft tissue
38
. Furthermore, delayed radiographs
would result in substantial cost savings without compromising
the quality of patient care, as already seen for noncomplicated
primary knee arthroplasty
39,40
. We further recommend that
radiograph sets be made between 3 and 6 months and at
12 months post-surgery, to allow the assessment of short-term
parameter progression (i.e., migration, bone formation, bone
resorption, notching, implant articular-surface wear) and the
documentation of implant status as a reference for later
examinations. There is no evidence that we are aware of sug-
gesting that long-term radiographic monitoring is more cost-
effective than performing clinical and radiographic check-up
examinations only for patients reporting symptoms
41
.
Application in Practice
Only widespread application of the present consensus in a
documentation system as well as clinical studies will foster
scientific comparability and transparency of reporting in
shoulder arthroplasty monitoring. We therefore developed a
printable form (see Appendix [Supplementary Data 2]) as well
as an electronic version available for REDCap
9
.Inafirst phase
of implementation, all parameters should be actively reported
without any documentation hierarchy; some parameters (e.g.,
migration) might have little to no relevance depending on the
observations made (e.g., loosening or fracture). However, an
option is provided to explain why a parameter cannot be
documented in specific circumstances. Finally, although this
monitoring system was developed for asymptomatic patients,
we recommend its systematic use when investigating the cause
of any symptoms that may occur.
Strengths and Limitations
We used a Delphi consensus process that favored the partici-
pation of a large international expert panel and achieved a high
response rate of 74% for the final survey. Although we had a
preconceived idea about which parameters should be consid-
ered, the initial survey was implemented mostly with open
questions to ensure that important parameters would not be
overlooked. Comments and suggestions were evaluated equally
without knowing the respondents’identity so as to avoid biased
judgments. Steering group members met informally during
professional meetings, notably in the context of the Interna-
tional Shoulder Arthroplasty Consortium
42
. Their individual
contributions were important to thoroughly address all
selected parameters and allow the formulation of a proposal
with an increased chance of support by the whole panel. While
we cannot exclude that another panel would have selected
other parameters or defined them differently, we believe that
the present proposal has face validity.
In large national and international registries, defined
radiographic parameters may well complement the commonly
used outcome of implant revision to identify problematic
implants sufficiently early after market introduction. These
issues cannot be resolved without wide multicenter application
of this monitoring tool and the centralization of standardized
data. Field application will almost certainly lead to the con-
tinuous evaluation and revision of our tool.
Conclusions
Through international consensus, we developed a radio-
graphic monitoring tool for asymptomatic patients after
Core Set of Radiographic Parameters for Shoulder Arthroplasty Monitoring
JBJS Open Access d2019:e0025. openaccess.jbjs.org 7
shoulder arthroplasty (SA), entitled “SA Radiological Mon-
itoring v1.0,”which includes a structured core set of
radiographic parameters. This work represents an impor-
tant step toward the standardization of documentation and
evaluation in shoulder arthroplasty. Clinical application
and scientific evaluation of the monitoring process are
needed.
Appendix
Supporting material provided by the authors is posted
with the online version of this article as data supplements
at jbjs.org (http://links.lww.com/JBJSOA/A119)(http://links.
lww.com/JBJSOA/A120). n
NOTE: Shoulder Arthroplasty (SA) Monitoring Steering Group members also include John Sperling,
MD, Mayo Clinic, Rochester, Minnesota; and Hans-Kaspar Schwyzer, MD, Shoulder and Elbow
Surgery, Schulthess Klinik, Zurich, Switzerland.
Clinical Investigators
Shoulder Arthroplasty Monitoring Consensus Panel members, who are listed alphabetically in
Appendix File 5, served as clinical advisors and participants in the Delphi process.
Participating Investigators
Melissa Wilhelmi, PhD (medical writer at Schulthess Klinik, Zurich, Switzerland), assisted with the
technical editing, language editing, and proofreading of the manuscript as well as provided
general administrative support during the submission process.
Holger Durchholz, MD
1,2
Bj¨
orn Salomonsson, MD
3
Philipp Moroder, MD
4
Simon Lambert, FRCS(Ed&Orth)
5
Richard Page, FRACS
6
Laurent Audig´
e, PhD
1
1
Research and Development (H.D. and L.A.) and Shoulder and Elbow
Surgery (L.A.), Schulthess Klinik, Zurich, Switzerland
2
Klinik Gut, St. Moritz, Switzerland
3
Karolinska Institutet Danderyds Sjukhus AB, Stockholm, Sweden
4
Charit´
e Universit¨
atsmedizin, Berlin, Germany
5
University College London Hospital, London, United Kingdom
6
Barwon Centre for Orthopaedic Research and Education, School of
Medicine, Deakin, University, Geelong, Victoria, Australia
Email address for L. Audig´
e: laurent.audige@kws.ch
ORCID iD for H. Durchholz: 0000-0001-8455-8703
ORCID iD for B. Salomonsson: 0000-0002-3437-7290
ORCID iD for P. Moroder: 0000-0002-0987-9926
ORCID iD for S. Lambert: 0000-0002-5823-1261
ORCID iD for R. Page: 0000-0002-2225-7144
ORCID iD for L. Audig´
e: 0000-0003-3962-3996
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