Introducing the forearm fracture index to define the diametaphyseal junction zone through clinical evaluation in a cohort of 366 diametaphyseal radius fractures

Abstract

Background
Unstable diametaphyseal radius fractures (DMRFs) can be prone to complications, and treatment strategies are heterogeneous. Studies are difficult to interpret as definitions of the diametaphyseal junction zone (DMJZ) are impractical for clinical use, imprecise, or prone to error.

Methods
We introduce the forearm fracture index (FFI) to define DMRFs in radiographs and ultrasound. The FFI is calculated by the ratio of the fracture’s distance to the distal radius growth plate over the width of the radius growth plate. The higher the FFI, the more proximal the fracture is. We define DMRFs to have an FFI between 1 and 2. All DMRFs treated at our institution between 2010 and 2020 were identified, and demographic data, fracture characteristics, and therapeutic strategies were assessed retrospectively. Comparative sub-analysis was performed between DMRFs(−) as defined in previous publications (Lieber in Unfallchirurg 114:292–299, 2011) and DMRFs( +) that were more proximal but still met our criteria.

Results
516 DMRFs were identified, representing 13.0% of all screened radius fractures. Excluding buckle fractures and patients lost to follow-up, 366 DMRFs were eligible for further analysis. Conservatively managed DMRFs were more distal than those managed operatively, represented by a lower FFI (1.28 vs. 1.34, p = 0.0051). 21 (5.7%) of all DMRFs were identified as DMRFs( +). These were significantly more dislocated and necessitated surgery more often than DMRFs(−) (52.4 vs. 24.6%, p = 0.009).

Conclusions
The FFI may be a good tool to identify and describe DMRFs. It can help guiding treatment decisions and make future studies on this entity more comparable.

Level of evidence
Study of Diagnostic Test, Level II.

Full text

Vol.:(0123456789)
Archives of Orthopaedic and Trauma Surgery (2025) 145:115
https://doi.org/10.1007/s00402-024-05664-0
RESEARCH
Introducing theforearm fracture index todefine thediametaphyseal
junction zone throughclinical evaluation inacohort of366
diametaphyseal radius fractures
ChristophvonSchrottenberg1 · RicardoBeck1· SusannMarieBeck1· ChristianKruppa1· MatthiasKuhn2·
PhilippSchwerk1· GuidoFitze1· JurekSchultz1
Received: 15 June 2024 / Accepted: 17 October 2024
© The Author(s) 2025
Abstract
Background Unstable diametaphyseal radius fractures (DMRFs) can be prone to complications, and treatment strategies are
heterogeneous. Studies are difficult to interpret as definitions of the diametaphyseal junction zone (DMJZ) are impractical
for clinical use, imprecise, or prone to error.
Methods We introduce the forearm fracture index (FFI) to define DMRFs in radiographs and ultrasound. The FFI is
calculated by the ratio of the fracture’s distance to the distal radius growth plate over the width of the radius growth plate.
The higher the FFI, the more proximal the fracture is. We define DMRFs to have an FFI between 1 and 2. All DMRFs treated
at our institution between 2010 and 2020 were identified, and demographic data, fracture characteristics, and therapeutic
strategies were assessed retrospectively. Comparative sub-analysis was performed between DMRFs(−) as defined in previous
publications (Lieber in Unfallchirurg 114:292–299, 2011) and DMRFs( +) that were more proximal but still met our criteria.
Results 516 DMRFs were identified, representing 13.0% of all screened radius fractures. Excluding buckle fractures and
patients lost to follow-up, 366 DMRFs were eligible for further analysis. Conservatively managed DMRFs were more
distal than those managed operatively, represented by a lower FFI (1.28 vs. 1.34, p = 0.0051). 21 (5.7%) of all DMRFs were
identified as DMRFs( +). These were significantly more dislocated and necessitated surgery more often than DMRFs(−)
(52.4 vs. 24.6%, p = 0.009).
Conclusions The FFI may be a good tool to identify and describe DMRFs. It can help guiding treatment decisions and make
future studies on this entity more comparable.
Level of evidence Study of Diagnostic Test, Level II.
Keywords Diametaphyseal junction zone· Distal radius fracture· Diametaphyseal radius fracture· Metadiaphyseal·
TEPIK
Abbreviations
a.p. Anterior–posterior
DMJZ Diametaphyseal junction zone
DMRF Diametaphyseal radius fractures
ESIN Elastic stable intramedullary nailing
FFI Forearm fracture index
IQR Interquartile range
K-wire Kirschner-wire
PCCF AO pediatric comprehensive classification of
long bone fractures
TEPIK Transepiphyseal percutaneous intramedullary
Kirschner-wire
Introduction
Most pediatric fractures affect the upper limb, with 36–40%
involving the radius or the ulna [2–5]. The distal forearm
is the most frequent location of injury, with 19–33% of
all fractures occurring there [2, 5]. However, literature on
* Christoph von Schrottenberg
Christoph.vonschrottenberg@ukdd.de
1 Department ofPediatric Surgery, Faculty ofMedicine
andUniversity Hospital Carl Gustav Carus, TUD
Dresden University ofTechnology, Fetscherstraße,
74,01307Dresden, Germany
2 Institute forMedical Informatics andBiometry, Faculty
ofMedicine, Technical University Carl Gustav Carus,
Dresden, Germany
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Archives of Orthopaedic and Trauma Surgery (2025) 145:115 115 Page 2 of 9
the incidence of fractures in the diametaphyseal junction
zone (DMJZ) is scarce [6]. Unstable diametaphyseal radius
fractures (DMRFs) are a matter of great interest to pediatric
surgeons. Loss of reduction, refractures, and limited
remodeling can make the treatment challenging [7–10]. The
AO Pediatric Comprehensive Classification of Long Bone
Fractures (PCCF) disregards fractures within the DMJZ as
an own entity. It defines the metaphysis as a square over
the growth plates of the radius and ulna (Fig.1a). The
area proximal to this square is the diaphysis. The PCCF
follows anatomical structures and has little predictive value
concerning treatment strategies or prognosis [11–14].
Existing definitions of the DMJZ are inconsistent, making
it difficult to compare studies and surgical techniques.
Lieber et al. defined the DMJZ as the part of the
metaphysis proximal to the square over the radius growth
plate alone (Fig.1, a) [1]. Another definition by Kim
etal. requires multiple variables as DMRFs are defined as
“fracture[s] with (1) the distance between the fracture line
and the distal articular surface between 35 and 60mm; (2)
the ratio of the length of distal fragment to the total length
of radius within 25%; and (3) the ratio of the maximal
diameter at 2cm proximal to the fracture line to that at
2cm distal to the fracture line within 70%” [15]. A third
definition characterizes the DMJZ as the distal third of the
radius minus the square of the width of the radius growth
plate [16]. It is difficult to use the latter two definitions in
clinical practice as most radiographs do not show the entire
forearm to reduce radiation exposure; hence, the distal third
of the radius cannot be defined in many cases. Moreover,
these classifications provide little prognostic information. To
provide help in selecting a therapeutic strategy for DMRFs,
a recent study advocates dividing the DMJZ as defined by
Lieber etal. into a proximal, an intermediate, and a distal
third [1, 17].
To take this idea further and to overcome the
aforementioned difficulties, we introduce the forearm
fracture index (FFI), a measure to define and further
locate DMRFs on radiographs and ultrasound. Advantages
and disadvantages of this classification will be outlined,
including its applicability to ultrasound which has become
increasingly important in diagnosing distal radius fractures
[18–21]. Finally, fracture characteristics and therapy
strategies in a cohort of 366 patients with DMRFs will be
assessed, and subgroup analysis will be performed between
DMRFs(-) defined according to Lieber etal. and fractures
that were located more proximally but still considered
DMRFs( +) as defined by our group.
Materials andmethods
Introducing theforearm fracture index anddefining
thediametaphyseal junction zone
The FFI was calculated as follows: the ratio of the fracture’s
distance to the radius growth plate (D) in the lateral
Fig. 1 a Anterior–posterior radiograph (a.p.) of the right distal
forearm of a 12-year-old patient with a complete diametaphyseal
radius fracture (DMRF); A marks the width of the growth plate of the
radius; B marks the combined width of the growth plate of radius and
ulna; C marks the diametaphyseal junction zone (DMJZ) as defined
by Lieber et al.; b a.p. radiograph of the right distal forearm of a
12-year-old patient with a complete DMRF; A’’ marks the DMJZ as
defined by our group; DMRFs as defined by Lieber etal. are located
within the red rectangle and marked DMRF(-); DMRFs as defined
by our group but proximal to DMRF(-) are located within the orange
rectangle and are marked DMRF( +); c Lateral radiograph of the right
distal forearm of a 12-year-old patient with a complete DMRF; D
marks the distance from the fracture line to the growth plate; the ratio
of D over A defines the forearm fracture index (FFI). DMRFs have an
FFI > 1 and ≤ 2
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Archives of Orthopaedic and Trauma Surgery (2025) 145:115 Page 3 of 9 115
radiograph over the radius growth plate’s width (A) in the
anterior–posterior (a.p.) radiograph (Fig.1c).
FFI = D/A
If this ratio is between 1 (distal limit) and 2 (proximal
limit), the fracture is termed a DMRF. Fractures of the radius
could hence be categorized as:
• Epiphyseal—for these fractures, the FFI does not apply;
• Metaphyseal—these fractures have an FFI of < 1;
• Diametaphyseal—these fractures have an FFI of > 1
and ≤ 2;
• Diaphyseal—these fractures have an FFI of > 2;
• Proximal—for these fractures, the FFI does not apply;
Clinical evaluation ofthenew definition oftheDMJZ
We retrospectively analyzed all forearm fractures in patients
aged 16years or younger treated at our institution from
2010 to 2020. This study was approved by our local ethics
committee (EK 433102016). Data was retrieved using
ICD-Codes S52.0–S52.9. Duplicates were eliminated.
Further exclusion criteria were falsely coded fractures,
solitary fractures of the ulna, pathological fractures, and
closed growth plates in the initial radiograph. Buckle
fractures and fractures lost to follow-up were included in
the categorization of radius fractures but were excluded from
further analysis. A patient flow diagram is provided in the
Supplementary Material (FigureS1) [22].
The FFI was calculated as described above and all DMRFs
(FFI > 1 and ≤ 2) were further analyzed. Demographic and
clinical data were collected and, using IMPAX EE Version
R20 XIX (AGFA HealthCare, Mortsel, Belgium), the
following geometric parameters and variables were assessed
in initial radiographs and during follow-up: the angulation
in degree, the translation in percentage of the shaft’s width
at the level of the fracture, the angle of the fracture line
in degree and whether a shortened fracture was present.
A comparative sub-analysis of fracture characteristics and
therapy strategies was performed between fractures that met
Lieber etal.’s criteria, termed DMRFs(−), and those that
were defined as diaphyseal fractures by Lieber etal. but still
considered a DMRF by our definition, termed DMRFs( +)
[1].
Comparison of metric data was performed using the t-test
with Welch’s correction, and results were displayed as mean
values with standard deviation when data was normally
distributed. The Mann–Whitney-U-test was used when data
was not normally distributed, and results were displayed
as median values with interquartile ranges. Categoric data
was compared using the Fisher exact test or the Chi-Square
test when applicable. Data curation and statistical analysis
were performed using GraphPad Prism version 8.4.3 for
Windows, GraphPad Software, San Diego, California, USA
(www. graph pad. com).
Results
Categorization ofall radius fractures using
theforearm fracture index
3956 radius fractures were identified. Of these, 59.5%
affected the distal metaphysis, 15.1% the diaphysis, 7.5%
the distal epiphysis and 4.8% were proximal, the majority
of which were fractures of the radial neck. The remaining
516 (13.0%) were fractures of the DMJZ (Fig.2). Of these,
132 (25.6%) were buckle fractures and 18 (3.5%) patients
were lost to follow-up. After exclusions, 366 DMRFs in 366
patients (262 male, 104 female; p < 0.0001) were available
for further analysis. The median age at the time of the
accident was 8years (IQR, 6–11years).
Applicability oftheforearm fracture index
inultrasound
To define the DMJZ using ultrasound, an assessment of the
radius growth plate’s width is necessary. This can be done
by holding a linear transducer orthogonally to the patient’s
palmar forearm perpendicular to the radius axis. Sliding
towards the wrist joint, the radius shaft must be in the center
of the screen. Towards the growth plate, the diameter of the
radius shaft increases continuously until the growth plate
appears and the echogenic cortex disappears. The width
of the radius metaphysis just proximal to where the cortex
disappears approximates the width of the radius growth plate
(Fig.3). The growth plate itself is hypoechogenic, lacking
Fig. 2 Distribution of localization of 3956 radius fractures in
patients ≤ 16 years of age admitted to our tertiary pediatric trauma
center from 2010 to 2020
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Archives of Orthopaedic and Trauma Surgery (2025) 145:115 115 Page 4 of 9
the clear soft-tissue-to-bone interface that characterizes
skeletal ultrasound.
Fracture characteristics of366 diametaphyseal
radius fractures andcomparison betweenDMRFs(‑)
andDMRFs( +)
Median radiologic follow-up lasted 38 days (IQR,
29.4–60days). The mean FFI of the cohort was 1.29 ± 0.22
(range, 1.01–1.97). Of the 366 DMRFs included, 345
were identified as DMRFs(−) [23]. 21 fractures were
identified as DMRFs( +), as their FFI was between 1 and
2 but proximal to the area defined by Lieber etal. The FFI
differed significantly between DMRFs(−) and DMRFs( +)
(1.26 ± 0.19, [range, 1.01–1.87] vs. 1.77 ± 0.15, [range,
1.42–1.97]; p < 0.0001). Dividing our cohort into distal,
intermediate, and proximal DMRFs using the FFI resulted
in 65.8% distal, 26.5% intermediate, and 7.7% proximal
DMRFs [17]. 220 (60%) of all DMRFs were complete,
while 40% were greenstick fractures. This rate did not
differ between DMRFs(−) and DMRFs( +). Median
angulation in the a.p. radiograph was 6° (IQR, 2–11°) and
was significantly increased in DMRFs( +) compared to
DMRFs(−) (12 vs. 6°, p = 0.0003). Median angulation in
the lateral radiograph was 17° and did not differ between the
two groups (17 vs. 20°, p = 0.309).
132 fractures (36.1%) presented with a translation in the
a.p. radiograph with a median dislocation of 25% of the
shaft’s width (IQR, 17–46%). There was no statistically
significant difference in the incidence (36.2 vs. 33.3%,
p > 0.9999) or the severity (25% [IQR, 17–44%] vs.
40% [IQR, 18–55%]; p = 0.389) of translation in the a.p.
radiograph between DMRFs(−) and DMRFs( +). 107
fractures (29.2%) presented with a translation in the lateral
radiograph with a median dislocation of 100% (IQR,
40–100%) of the shaft’s width. There was no significant
difference in the incidence (30.1 vs 14.3%, p = 0.1434) or the
severity (100% [IQR, 36–100%] vs. 100% [IQR, 100–100%];
p = 0.2055) of translation in the lateral radiograph
between patients with DMRFs(−) and DMRFs( +). The
overall median angles of the fracture line in the a.p. and
lateral radiographs were 8° and 14°, respectively. These
angles differed significantly between DMRFs(-) and
DMRFs( +) (a.p.: 7 vs. 17°, p = 0.0112; lateral: 13 vs. 33°,
p < 0.0001). 24 DMRFs (6.6%) were oblique fractures
with a fracture line angle in the a.p. radiograph of > 30°.
The rate of oblique fractures was significantly increased
in the group of DMRFs( +) compared to DMRFs(-) (33.3
vs. 4.9%, p = 0.0001). The rate of shortened fractures
was 20.2% and did not differ between the two groups. All
fracture characteristics are displayed in TableS1 of the
Supplementary Materials.
Therapy strategies inDMRFs(−) andDMRFs( +)
withregard totheFFI
In this study’s cohort of 366 DMRFs, 270 fractures
(73.8%) were managed conservatively, 215 of which
required reduction initially, which was performed under
analgosedation in the outpatient clinic/emergency ward. 9
conservatively managed fractures (3.3%) were immobilized
in a forearm cast; all others were immobilized in an upper
arm cast. 96 patients (26.2%) underwent surgery under
general anesthesia. The preferred osteosynthesis was
transepiphyseal percutaneous intramedullary Kirschner-
wire fixation (TEPIK) as described by our group
previously and was performed in 56 patients (58.3%) [24].
Bicortical Kirschner-wire (K-wire) fixation via the radial
styloidprocess or the radial metaphysis proximal to the zone
of Ranvier was performed in 16 patients (16.7%) [25, 26].
Fig. 3 a Transverse ultrasound of the palmar distal forearm; A
marks the width of the radius at the level immediately proximal to
the growth plate which approximates the width of the radius growth
plate; b Longitudinal ultrasound of the lateral distal radius; A’ marks
the width of the radius growth plate as determined in the transverse
ultrasound and is applied twice to determine the diametaphyseal
junction zone A’’
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Archives of Orthopaedic and Trauma Surgery (2025) 145:115 Page 5 of 9 115
Elastic stable intramedullary nailing (ESIN) was used in
19 patients (19.8%), and 5 patients (5.2%) received plate
osteosynthesis [27–31].
Osteosynthesis was performed significantly more
often in DMRFs( +) than in DMRFs(−) (52.4 vs. 24.6%,
p = 0.009). The preferred osteosynthesis for DMRFs(−)
was TEPIK (61.2%), while for DMRFs( +), ESIN
osteosynthesis was performed more frequently (63.6%).
Table 1 gives an overview of the different therapy
strategies.
Conservatively treated DMRFs had a significantly
smaller FFI than operatively treated DMRFs (1.27 ± 0.22
[range, 1.01–1.89] vs. 1.34 ± 0.28 [range, 1.01–1.97]).
Figure4 visualizes treatment strategies (operative vs.
conservative) in co-occurrence with the FFI.
DMRFs managed with TEPIK had an FFI of 1.30 ± 0.27
(range, 1.01–1.97), bicortical K-wire fixated DMRFs
had an FFI of 1.22 ± 0.22 (range, 1.02–1.76), while
those managed with ESIN had an FFI of 1.61 ± 0.22
(range, 1.18–1.92). Finally, DMRFs managed with
plate osteosynthesis had an FFI of 1.24 ± 0.13 (range,
1.03–1.38). The co-occurrence between the FFI and the
different surgical techniques is displayed in Fig.5.
Table 1 Different therapeutic
approaches for diametaphyseal
radius fractures
Frequencies of the different therapeutic approaches for diametaphyseal radius fractures (DMRFs) in
our cohort of 366 patients and comparison between DMRFs(-) and DMRFs( +); *percentages refer to
all patients treated conservatively in the respective column; **percentages refer to all patients treated
operatively in the respective column; FFI, forearm fracture index; TEPIK, transepiphyseal percutaneous
intramedullary Kirschner-wire osteosynthesis; ESIN, elastic stable intramedullary nailing
cohort
(n = 366)
DMRF(-)
(n = 345)
DMRF( +)
(n = 21)
p
Conservative 270 (73.8%) 260 (75.4%) 10 (47.6%) 0.009
*Forearm cast 9 (3.3%) 9 (3.5%) – –
*Upper arm cast 261 (96.7%) 251 (96.5%) 10 (100%) > 0.9999
Operative 96 (26.2%) 85 (24.6%) 11 (52.4%) 0.009
**TEPIK-osteosynthesis 56 (58.3%) 52 (61.2%) 4 (36.4%) 0.192
**Bicortical Kirschner-wire fixation 16 (16.7%) 16 (18.8%) – –
**ESIN-osteosynthesis 18 (18.8%) 11 (12.9%) 7 (63.6%) 0.0006
**Plate-osteosynthesis 5 (5.2%) 5 (5.9%) – –
Outpatient treatment 254 (69.4%) 244 (70.7%) 10 (47.6%) 0.0476
Fig. 4 Conditional density plot shows percentages of operatively
and conservatively treated diametaphyseal radius fractures (DMRFs)
depending on the forearm fracture index (FFI) in 366 patients
admitted to our tertiary pediatric trauma center between 2010 and
2020
Fig. 5 Conditional density plot shows percentages of various
techniques of osteosynthesis depending on the forearm fracture
index (FFI) in 96 surgically managed diametaphyseal radius fractures
(DMRFs) admitted to our tertiary pediatric trauma center between
2010 and 2020; ESIN, elastic stable intramedullary nailing; TEPIK,
transepiphyseal percutaneous intramedullary Kirschner-wire fixation
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Archives of Orthopaedic and Trauma Surgery (2025) 145:115 115 Page 6 of 9
Discussion
Introducing theforearm fracture index anddefining
thediametaphyseal junction zone
Applying the FFI to identify DMRFs, we have found an
incidence for DMRFs of 13.0% of all radius fractures.
This is in line with the recent literature reporting 16.1%
of all forearm fractures to be DMRFs [17]. These results
indicate that DMRFs are not rare and might represent
a relevant challenge for pediatric traumatologists. As
mentioned above, existing definitions of DMRFs bear
several weaknesses. For some, radiographs of the entire
forearm are necessary, which conflicts with the principle
of limited radiation exposure [15, 16]. Anatomic variants
such as ulna minor variants or twisted radiographs may
lead to imprecise values when the growth plate’s width
of radius and ulna combined need to be measured [1].
Furthermore, applying this distance to the radius in the
a.p. radiograph to define the DMJZ may lead to false
results in the case of a shortened fracture or an angulation
in the lateral radiograph, which represent the most
common displacements. In these cases, the distance from
the fracture line to the radius growth plate will appear
shorter than it actually is. This may lead to fractures
being misinterpreted as metaphyseal [1]. An example is
visualized in Figure S2 of the Supplementary Material.
Another disadvantage of existing definitions is their
limited value in describing the exact location of the fracture,
which is essential for choosing the right therapy strategy.
Stark etal. tried to overcome this by categorizing DMRFs
as defined by Lieber etal. into proximal, intermediate,
and distal ones [17, 23]. Instead, we present the FFI as a
continuous, quantitative variable that clearly distinguishes
between diaphyseal and diametaphyseal radius fractures
while unambiguously describing the exact fracture location
within the DMJZ. Using the FFI to define the DMJZ
may eliminate some sources of error. Measuring only
the width of the radius growth plate might be easier than
measuring the radius and ulna growth plates together. As
the fracture’s distance to the growth plate is assessed in the
lateral radiograph or with sonography, it is independent
of angulation in the lateral radiograph and any potential
shortening of the fracture. In case of angulation in the
a.p. radiograph, the distance can be assessed in the a.p.
radiograph or with ultrasound.
Nevertheless, in the rare case of severe angulation both
in the a.p. and the lateral radiograph, the FFI cannot be
determined reliably. In cases of severe displacement, it may
seem reasonable to take only one radiograph to indicate
surgery. Consequently, the radiograph of the second plane
can be spared in the emergency ward, which might hinder
determining the FFI preoperatively as well.
Our definition of the DMJZ (FFI > 1 and ≤ 2) includes
a slightly longer part of the radius than the definition
offered by Lieber etal., thus including 21 of 366 (5.7%)
fractures that would have been formerly classified as
diaphyseal [1]. Even though this is a small percentage,
this group of proximal DMRFs( +) is particularly
important to be accounted for. DMRFs( +) present with
an increased angulation in the a.p. radiograph (12 vs.
6°, p = 0.0003), which is the direction of dislocation less
likely to correct spontaneously [7, 9, 10]. Interestingly, in
our cohort, the overall incidence of oblique DMRFs with
a fracture line angle of > 30° in the a.p. radiograph was
6.6%, notably more than in the cohort analyzed by Stark
etal., who described this in only one patient (1.1%) [17].
Furthermore, the angles of the fracture line both in the a.p.
and the lateral radiographs were significantly increased
in DMRFs( +) (a.p.: 17 vs. 7°, p < 0.0112; lateral: 33 vs
13°, p < 0.0001), possibly making them more prone to
secondary dislocation. Consequently, DMRFs( +) were
treated operatively significantly more often (52.4 vs.
24.6%, p = 0.009).
Correlating thechoice ofosteosynthesis
withtheexact localization oftheDMRF
Among various techniques, the optimal therapeutic
strategy for DMRFs might depend on their exact
localization within the DMJZ [1, 17]. Accordingly,
conservatively treated DMRFs in our cohort had a
lower FFI than those treated operatively (1.27 vs. 1.34;
p = 0.005). Stark etal. divided their retrospectively
analyzed cohort of 88 DMRFs into distal (47.7%),
intermediate (29.5%), and proximal (22.7%) DMRFs and
found proximal DMRFs to be treated mainly with ESIN
or intramedullary K-wire-osteosynthesis. This tendency
is also found in our cohort since ESIN osteosynthesis
was most frequent in proximal DMRFs with a mean
FFI of 1.61 compared to the overall average of 1.27
(p < 0.0001). DMRFs managed with TEPIK (FFI = 1.30)
or bicortical K-wire fixation (FFI = 1.22) were rather
distal. In comparison, the preferred surgical technique
for distal DMRFs in the cohort analyzed by Stark etal.
was bicortical K-wire fixation. However, in our cohort
the variability of surgical techniques decreased over the
study period as TEPIK became the favored technique in
all unstable DMRFs after its establishment in 2010. While
Lieber etal. describe the styloid process as the preferred
entry point for TEPIK osteosynthesis, our entry point
for the K-wire lies distally to Lister’s tubercle, which
offers excellent results with no secondary dislocation.
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Archives of Orthopaedic and Trauma Surgery (2025) 145:115 Page 7 of 9 115
Metal removal was performed after 4weeks without any
anesthesia [23, 24].
Multiple surgical approaches for DMRFs, including
various techniques for intramedullary K-wire or ESIN
osteosynthesis such as the antegrade intramedullary nailing
of the radius, have been published as of today [8, 23, 24,
32, 33]. While most of these techniques have not been
universally accepted, antegrade intramedullary nailing of
the radius seems to become more and more popular due to
its good results and low risk of complications [15, 34–36].
One disadvantage of ESIN osteosynthesis still remains as
metal removal must be performed under a second general
anesthesia. Still, immobilization in a plaster cast until
metal removal poses a disadvantage of TEPIK against
ESIN osteosynthesis.
The FFI could be used to compare different surgical
techniques better, as it clearly categorizes and specifies
DMRFs, thus helping future trials.
Assessing theFFI withultrasound
Ultrasound has become an invaluable tool in diagnosing
distal radius fractures in children as it is free of radiation,
can be learned quickly, has a high degree of specificity
and sensitivity, and may increase the comfort for pediatric
patients as the diagnostic setting can be framed child-
friendly more easily [18–21]. Unfortunately, previously
published definitions of the DMJZ cannot be used in
ultrasound as it is not feasible to determine the length of the
entire radius [15, 16]. Also, the definition provided by Lieber
etal. can be challenging to apply to ultrasound images since
the limited width of many linear transducers hinders the
correct visualization of the ulna and radius growth plates
simultaneously. To determine the FFI in ultrasound, one
only needs to depict the radius growth plate, which can be
assessed quickly.
In some cases, the applicability of ultrasound to
diagnose distal radius fractures may not be feasible due to
severe dislocation [37]. In these cases, the FFI cannot be
determined via ultrasound.
Limitations
This study's limitations include its retrospective, single-
center design. With regard to the rate of surgically managed
DMRFs, a certain bias cannot be excluded as our institution
is a tertiary pediatric trauma center, hence complex fractures
necessitating surgery are often referred to us from peripheral
institutions. However, to our knowledge, this is the largest
cohort of patients with DMRFs systematically analyzed.
Furthermore, no standardized protocol for the choice of
the osteosynthesis was followed. During the study period,
the likelihood of choosing TEPIK osteosynthesis increased
because of the good results that were observed by our group
using this technique [24].
Conclusion
With a cohort of 366 patients, this is an extensive
retrospective analysis of DMRFs in children and adolescents.
We have introduced the FFI, a simple tool to define DMRFs
with an FFI between 1 and 2. It was shown that the choice
of various surgical approaches for DMRFs depends on their
localization, which can be expressed precisely using the
FFI. We propose that the FFI can be assessed by ultrasound
as measuring the width of the radius growth plate can be
learned quickly. The FFI may help make future studies
on DMRFs more comparable as it offers an objective,
quantifiable tool to define DMRFs and to differentiate within
the group of DMRFs. Prospective, randomized controlled
multi-center trials are needed to determine a standardized
surgical approach for various DMRFs stratified using the
FFI.
Supplementary Information The online version contains
supplementary material available at https:// doi. org/ 10. 1007/
s00402- 024- 05664-0.
Funding Open Access funding enabled and organized by Projekt
DEAL.
Data availability The data presented in this study are available on
request from the corresponding author.
Open Access This article is licensed under a Creative Commons
Attribution 4.0 International License, which permits use, sharing,
adaptation, distribution and reproduction in any medium or format,
as long as you give appropriate credit to the original author(s) and the
source, provide a link to the Creative Commons licence, and indicate
if changes were made. The images or other third party material in this
article are included in the article's Creative Commons licence, unless
indicated otherwise in a credit line to the material. If material is not
included in the article's Creative Commons licence and your intended
use is not permitted by statutory regulation or exceeds the permitted
use, you will need to obtain permission directly from the copyright
holder. To view a copy of this licence, visit http:// creat iveco mmons.
org/ licen ses/ by/4. 0/.
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