(2024) 24:585
Wang et al. BMC Pediatrics
https://doi.org/10.1186/s12887-024-05063-9

BMC Pediatrics

RESEARCH

Open Access

Ulnar lengthening for children with forearm
deformity from hereditary multiple exostoses:
a retrospective study from a tertiary medical
center
Shuo Wang1†, Bomansaan Herman1†, Yiheng Wu2†, Ming Lei1, Blessing Mutasa3, Pan Hong1* and Jin Li1*

Abstract
Background Patients with hereditary multiple exostosis (HME) usually present with forearm deformity with or without radial head dislocation. Ulna lengthening has been proposed to address this condition. Exostosis resection
plus ulna lengthening has been adopted in our hospital since 2008, and patients with this condition were retrospectively reviewed. Herein, we aimed to investigate the optimal timing and clinical outcomes of this surgical approach.
Methods In all, thirty-five patients (40 forearms), including 22 boys and 13 girls, were enrolled in our study from July
2014 to September 2020. We divided the patients into 4 groups based on the age when they received surgery
and the status of the radial head. Pronation and supination of the forearm, flexion and extension of the elbow, wrist
ulnar deviation and wrist radial deviation, and radiological parameters including ulnar length (UL), ulnar variance (UV),
the percentage of radial bowing (RB/RL), radio articular angle (RAA) and carpal slip (CS), were assessed and recorded.
Results The mean UL was significantly improved after surgery in four Groups (P<0.05). In patients with radial headdislocation, we found significant improvement in forearm, wrist function and elbow flexion (p < 0.05). For the patientswith radial head dislocation, the juniors demonstrated better improvement in % RB and RAA (p<0.05, p = 0.003
and 0.031).
Conclusion Exostosis resection and ulna lengthening with unilateral external fixation can effectively improve
the function and radiological parameters of forearm deformity in HME children. For patients with radial head dislocation, early surgery can achieve better results. For patients not associated with radial head dislocation, we recommend
regular follow-up and surgical treatment after 10 years of age.
Keywords Hereditary multiple exostosis, Radial head dislocation, Forearm deformities, Ulnar lengthening†

Shuo Wang, Bomansaan Herman and Yiheng Wu contributed equally to thiswork.
*Correspondence:
Pan Hong
hongpan2013@foxmail.com
Jin Lilijinwhxh2003@foxmail.com
Full list of author information is available at the end of the article© The Author(s) 2024. Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0
International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as longas you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if
you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article orparts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicatedotherwise 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
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view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/.

Wang et al. BMC Pediatrics(2024) 24:585

Background
Hereditary multiple exostosis (HME) is a type of skeletal dysplasia, with approximately 1/50,000 incidence
in the population [1, 2]. Exostosis often grow in themetaphysis of the long bone and can cause growth disorders and deformities [1, 3]. Forearm deformities arereported in 30–60% of patients with HME. According
to Masada’s classification system [4], forearm deformities can be divided into four types, see Fig. 1. Clinically,
HME presents with deformities such as wrist ulnar deviation, radial head dislocation, ulnar shortening, and radialbowing [1, 2, 4–6]. Patients with HME usually come tothe hospital with local pain, functional limitations andappearance abnormalities.
The purpose of surgical intervention is to correct theskeletal deformity, reduce the dislocation of the radialhead and improve the forearm function. Ulnar osteotomy
combined with lengthening, simple radial head resection,and distal radial hemiepiphysiodesis has been reported
to address this deformity [2, 6, 7]. However, the optimal treatment algorithm for patients with this condition
remains controversial [2, 6–9].
In this study, we retrospectively reviewed 36 patientswith this condition receiving ulnar osteotomy andlengthening, and patients at different age groups werecompared. We aimed to evaluate the effect of ulnar osteotomy lengthening in patients of different ages and provide insights into the optional surgical timing.

Page 2 of 10

22 boys and 13 girls, were retrospectively reviewed, seeFig. 2. All patient information was obtained from thehospital database. The study was approved by the Ethics
Committee of Tongji Medical College, Huazhong University of Science and Technology.
Grouping criteria

The patients were grouped according to the status ofradial head dislocation into the dislocation group andthe non-dislocation group. Then they were subdivided
into 4 groups according to their ages receiving surgery(age ≤ 10 years or > 10 years): (1) Junior with radial headdislocation (The J-D group), (2) Junior without radialhead dislocation (The J-N group), (3) senior with radialhead dislocation (The S-D group), and (4) senior without
radial head dislocation (The S-N group).
Inclusion criteria

The patients had a diagnosis of HME and at least one of
the following radiographic or functional parameters: (1)the ulna is shorter than the radius by > 5 mm, (2) a radial

Methods
Patients

In all, from July 2014 to September 2020, 52 children
with forearm deformities from HME were admitted toour hospital. Finally, 35 patients (40 forearms), including

Fig. 1 Masada classification of the forearm osteochondroma

Fig. 2 Flowchart of patient selection

Wang et al. BMC Pediatrics(2024) 24:585

Page 3 of 10

Fig. 3 Flowchart of patient selection. Osteochondroma resection(a), ulna osteotomy(b), ulna extension using a unilateral external fixator (c, d),remove the external fixator(e)Fig. 4 Radiological presentations of a 7-year-old boy with HME with a forearm deformity. Preoperative radiographs of the patient showed distal
ulnar exostosis, ulnar shortening, and radial head dislocation (Masada IIb type) (a). Postoperative radiography of ulnar osteotomy and lengthening
surgery (b). Radiological presentation of one, two and six months after surgery (c, d and e). Radiographic picture of fourteen months after surgery
showing correction of the deformity and radial head reduction (f)Wang et al. BMC Pediatrics(2024) 24:585

Page 4 of 10

Fig. 5 Radiographic parameters. (1) RB, radial bowing (the maximum distance from the ulnar border of the radius to the long axis of the forearm
was measured and then divided by the radial length). (2) UL, ulnar length (the length of the ulna was measured); UV, ulnar variance (the distal
ulnar shortening from the most distal ossified point of the ulna to the plane of the distal radial surface); RAA, radio articular angle (the angle
of inclination of the distal articular surface of the radius to the long axis of the forearm). (3) carpal slip (the percentage of the lunate on the ulnarside of a continuation of the linear axis of the forearm)

articular angle of > 30 degrees, (3) a carpal slip of > 60%(Fig. 5), (4) dislocation of the radial head, (5) limitationof forearm movement that interferes with daily activities.
Patients who meet one or more of the 5 inclusion criteria
are selected for the first time. Among all patients undergoing surgery, we excluded cases with the following conditions: (1) patients with metabolic diseases, (2) previous
surgery on the same limb, (3) patients with incomplete
data, (4) additional surgery for this treatment (other thanexostosis resection and ulna lengthening) (Fig. 2).
Surgical methods

Three senior surgeons performed surgeries. The treatment procedure is described in Fig. 3. All procedures
were performed under general anaesthesia and tourniquet control (180-200 mmHg for a maximum of 60 min).
According to the location of the exostosis, a longitudinal
incision was made on the forearm. The preferred locationfor osteotomy was the proximal one-third to one-fourthof the ulna. The osteotomy was performed using a sharp
drill and a chisel. Four Schanz pins (diameter 3 or 4 mm)
were placed on the ulna in parallel. The external fixator(YIJIABAO, China) was then connected between these
Schanz screws. All patients underwent ulnar or radius
exostosis resection and ulnar lengthening using a unilateral external fixator.
One week after surgery, the ulna was extended in
0.25 mm increments 3 to 4 times daily to achieve a traction rate of 0.75 to 1 mm/ day. Follow-up was conductedin the second week, 1 month and every 1 month after.
The increase in the ulna axis and degree of callus at theosteotomy region could be monitored by X-ray. Radiological presentations of a 7-year-old boy with HME witha forearm deformity were showed in Fig. 4. Parents should
pay attention to their child’s forearm sensation, range of
motion, and peripheral circulation. Parents could contact
us by phone or visit the hospital whenever the children
experience discomfort during the extension process. The
distraction was discontinued when the radial head showed
reduction or positive ulnar variance reached 5 mm (theTable 1 The demographic characteristics
Number/Mean(±SD)

Percentage（%）

Boys

22

62.9

Girls

13

37.1

Right

11

31.4

Left

19

54.3

Bilateral5

14.3

The junior group(N/D)

23(12/11)

57.5

The senior group(N/D)

17(8/9)

42.5

I

16

40.0

IIa

9

22.5

IIb

15

37.5

Age

9.04(±3.49)

During of follow-up

21.22(±14.06)

Sex

Side

Modified classification

The junior group(y≤10); The senior group(y＞10)
N:without radial head dislocation
D:with radial head dislocation
SD Standard deviation

Wang et al. BMC Pediatrics(2024) 24:585

ulna was longer than the radius). The external fixator was
kept in place until the distracted region demonstrated
consolidation on the X-ray, or a plate could be inserted tomaintain the length until the bone union was achieved.
We performed a retrospective study in which two doctors measured and collected all data. Before and after
surgery, we evaluated imaging and functional outcomes.
Based on the radiographic imaging, the following parameters for each forearm were assessed in Fig. 5: (1) the percentage of radial bowing( radial bowing divided by radial
length; RB/RL) (2) ulnar length, ulnar variance, radio
articular angle (3) carpal slip; Considering that some of
the younger children had incomplete metacarpal development, carpal slip was not included as a reference in theyounger groups. Functional results include the pronationand supination of the forearm, the flexion and extension of
the elbow, wrist ulnar deviation and wrist radial deviation.
Statistical analysis

Statistical analysis was performed with SPSS statisticalsoftware (version 25.0; SPSS, Chicago, IL, USA). Continuous variables were summarized as the mean and thestandard deviation (SD). The parametric KolmogorovSmirnov test was used to check for normal distributionof the data. A matched-sample T-test was used for functional and imaging indicators before surgery and at thelast follow-up visit. Two independent sample T-tests
were used to compare the imaging and functional indicators of the J-N and S-N groups. The J-D and S-D groups
used the same method. The Fisher exact test was used fornominal variables. The level of significance was set at a
p-value < 0.05.

Page 5 of 10

pronation increased significantly from 66.0±4.34°to
79.89±4.99°(p＜0.001). In the J-D group, the %RB and
RAA of preoperative and last follow-up recorded p valuesof 0.003 and 0.031, respectively, which were statisticallysignificant. Also, the forearm rotation function, Wrist
ulnar deviation, and Wrist radial deviation were significantly improved (p<0.05).
The senior groups

In the S-N group, the average CS decreased from54.12±22.01% to 40.24±14.12% (p = 0.039). Forearm
pronation increased significantly from 64.25°±11.29°to
78.25°±7.80°(p＝0.014). In the S-D group, the % RB and
RAA of preoperative and last follow-up recorded p valuesof 0.083 and 0.069, respectively, which were statistically
non-significant. However, the forearm rotation function,
wrist ulnar deviation and wrist radial deviation were significantly improved (p<0.05).
CompareThe mean UL was significantly improved after surgery infour Groups (P＜0.05). For patients without dislocation,
Table 2 Radiographic outcomes in the patients without radialhead dislocation

In the J-N group, the average UV decreased from0.53±0.23cm to -0.04±0.45cm (p = 0.01). Forearm

Differencea

P Value

The J-N12.95（±2.08）

15.89（±2.31）-2.94（±2.05)

0.005*The S-N

16.88（±2.83）

18.96（±3.53）-2.08（±1.09）

0.032*

P’ Value

0.021

0.097

0.459

The J-N

0.53（±0.23）-0.04（±0.45）

0.57（±0.53）

0.019*The S-N0.47（±025）0.13（±0.29）

0.34（±0.23）

0.062

P’ Value

0.683

0.511

0.434

The J-N

9.40（±2.47）

9.24（±2.90）

0.17（±1.26）

0.720

The S-N

9.48（±2.53）

8.31（±2.57）

1.17（±1.82）

0.288

P’ Value

0.960

0.602

0.285

The J-N

24.18（±3.09）

22.46（±2.22）

1.72（±3.14）

0.165

The S-N

29.26（±4.07）

26.80（±4.01）

2.47（±3.52）

0.256

P’ Value

0.036

0.034

0.717

54.12（22.01）

40.24（±14.12）

15.24（±8.02） 0.039*

UV

Study population

The junior groups

Last Follow-upa

UL

Results
This study included 35 pediatric patients with HME(40 forearms). Twenty-two patients were boys, and 13
were girls. The mean age receiving the surgery was 9.04(±3.49) years (range, 3.5 to 15.2 y; median= 8.3 y). The
junior group included 20 patients (age range,3.5 to 9.8 y;median=7.5 y) and 23 forearms, including 11 forearms
with radial head dislocation. The senior group included
15 patients (age range,10.2 to 15.2 y; median=12.5 y)and 17 forearms, including 9 forearms with radial headdislocation. The mean follow-up time was 21.22(±14.06)
months. According to the Masada classification system,
16 forearms (40.0%) were classed as Type I; 9 (22.5%), as
Type IIA; and 15 (37.5%), as Type IIB. The patient demographics are shown in Table 1.

Preoperativea

%RB

RAA​

CS
The J-NThe S-N
P’ Value
The S-N Group consists of patients older than 10 years without radial headdislocation（n=8）
The J-N Group consists of patients aged 10 years or less without radial headdislocation（n=12）
UL Ulnar lengthening, UV Ulnar variance, RB Radial bowing, RAA​Radial articularangle, CS Carpal slip, P data between the pre-op and the last follow-up; P’ data
between the junior group and the senior groupa

The values are given as the mean and the standard deviation*

denotes P < 0.05

Wang et al. BMC Pediatrics(2024) 24:585

there was no significant difference in imaging and functional improvement between the younger and older
groups. For patients with radial head dislocation, theradial head was reduced at the last follow-up. The difference in radiographic indexes was mainly %RB and RAA.
In the J-D group, the %RB and RAA of preoperativeand last follow-up recorded p values of 0.003 and 0.031,
respectively, which were statistically significant. The S-D
group recorded P values of 0.083 and 0.069, respectively,
which are statistically non-significant. In patients withradial head dislocation, we found significant improvement
in forearm, wrist function and elbow flexion. However,there was no difference in the improvement of functional parameters before and after operation between theyounger group and the older group. Table 2 and Fig. 6
compare the radiographic parameters between groups
J-N and S-N. The radiographic results of patients inPage 6 of 10groups J-D and S-D are shown in Table 3 and Fig. 7. The
functional results in patients are shown in Tables 4 and 5.
Radial head reduction was not achieved in 4 patients at
the end of the lengthening in the S-D group, and additional surgery of radial head reduction or resection was
performed. Of all the patients, only one in the S-D group
underwent a radial head resection. At the end of ulna
lengthening, the head of the radius was excised, considering that the patient was older than 10 years and had
severe deformation of the head that affected reduction.
At the last telephone follow-up, none of the patients had
further dislocation of the radial head. We found threepatients in the J-D group who had relapsed. The main
manifestations of recurrence were tumor growth andlimited functional activities. One case of ulnar nonunion
was also found. No postoperative impingement symptoms were observed in any of the wrists.

Fig. 6 Comparisons between preoperative and follow-up radiographic measurements in patients without dislocation of radial head. * p < 0.05

Wang et al. BMC Pediatrics(2024) 24:585

Page 7 of 10

Table 3 Radiographic outcomes in the patients with radial headdislocation
Preoperativea

Last Follow-upa

Differencea

P ValueUL
The J-D

10.96（±1.72）

14.30（±2.11）-3.34（±1.51)

0.000*The S-D

14.45（±2.09）

17.34（±3.57）-2.89（±1.94）

0.002*

P’ Value

0.001*

0.029*0.573

UV
The J-D

0.91（±0.39）

0.08（±0.43）

0.82（±0.51）

0.000*The S-D

0.46（±0.51）-0.08（±0.29）

0.54（±0.70）

0.049*

P’ Value

0.039*

0.340

0.310

%RB
The J-D

8.84（±1.99）

7.12（±1.36）

1.72（±1.45）

0.003*The S-D

10.21（±2.31）

7.65（±1.88）

2.56（±3.86）

0.083*

P’ Value

0.173

0.473

0.516

RAA​
The J-D

27.64（±4.24）

24.86（±3.57）

2.78（±3.69）

0.031*The S-D

29.11（±5.87）

28.23（±3.58）

0.88（±5.43）

0.639

P’ Value

0.522

0.050

0.366

57.15（±18.12）

40.42（±18.07）

17.67（±12.10）

CS
The J-DThe S-D

0.003*

P’ Value
The J-D Group consists of patients aged 10 years or less with radial headdislocation (n=11)
The S-D Group consists of patients older than 10 years with radial headdislocation (n=9)
aThe values are given as the mean and the standard deviation*

denotes P <0.05

Discussion
Gradual ulna lengthening can effectively improve thefunction and radiographic results of forearm deformity in HME patients. For patients with radial headdislocation, the improvement in function is more significant. Radiographic parameters showed that the
improvement of radial deformities was more significant in younger patients with dislocation. Although noradial deformity correction was performed, % RB was
improved during ulna lengthening, and the improvement of % RB and RAA was more pronounced in the
J-D group (P = 0.003; P = 0.031), which is consistent
with some studies [10–14]. Ulna lengthening facilitates
the correction of radial deformities due to spontaneous bone remodeling in pediatric patients [10, 11]. The
traction force in the ulnar against the radius throughthe distal radioulnar joint and interosseous membrane reduces the radial head and contributes to theimprovement in the RB [12–14]. Hsu et al., in theirstudy, observed similar results in patients (≤ 10 yearsof age) who did not undergo corrective radial osteotomy [15].

An essential goal of surgical intervention for forearm
deformities is to disrupt the progression of deformities
and dysfunction, especially radial head dislocation [12].
Some scholars believe that resection of osteochondroma alone can effectively improve the functional
activities of the forearm and delay the progression of thedeformity [16, 17]. However, resection of osteochondroma alone did not improve the radiographic parameters [17, 18]. In our study, all patients underwent ulna
and radius osteochondroma resection and gradual ulnar
lengthening, and the patients achieved good radiologicaland functional results after surgery. Many studies havereported good radiographical and functional results after
osteochondroma resection and gradual ulnar lengthening [10, 15, 19]. In addition, the recurrence of ulnar
shortening and radial head dislocation can be reduced by
the resection of osteochondroma before the correction ofulnar shortening and deformity [20, 21].
In recent years, gradual ulnar lengthening has been
considered by most scholars as a crucial surgical step
to correct forearm deformities [11, 22, 23]. However,
the exact procedure and timing of surgical intervention
remains controversial. First of all, the choice of osteotomy point is significant. The proximal third of the ulna
for the osteotomy does not damage critical anatomical
structures such as the interosseous membrane and theproximal oblique cord [24]. The tension of the interosseous membrane is conducive to reducing the radius head
during the elongation process [20]. Subsequently, theulna was gradually lengthened using an external fixator,
which allows controlled lengthening and possible reduction of the radial head without significant soft tissue
damage [25].
Regarding the selection of external fixators, manystudies have applied unilateral external fixators to treat
forearm deformities caused by HME and achieved goodresults [10, 11, 25, 26]. In this study, we used a unilateralexternal fixator to extend the ulna. During the follow-up,
we found that due to the advantages of small size andeasy postoperative care, most patients said the impact
on their daily lives was acceptable. Also, when comparedwith other lengthening devices, the complication rates
appear to be lower with unilateral fixators [27].
There is debate as to whether the outcome of early corrective surgery is superior to that of untreated patientsin all patients [11, 18]. In this study, for type I patients,
both age groups obtained good postoperative radiographical results. There was no significant difference
between the two groups. For patients with radial headdislocation, both groups showed significant improvement in motor function except elbow flexion. However,Wang et al. BMC Pediatrics(2024) 24:585

Page 8 of 10

Fig. 7 Comparisons between preoperative and follow-up radiographic measurements in patients with dislocation of radial head. * p < 0.05

significant improvement in radial malformations wasfound in the younger group on imaging (The % RB and
RAA of preoperative and last follow-up in the J-D group
recorded p values of 0.003 and 0.031). Hsu et al. reported
that postoperative radial deformities were also significantly improved in the younger group of patients who
underwent only gradual ulnar lengthening (The average
RAA decreased from 35.8°± 5.2°to22.9°± 4.7°(p = 0.028))[15]. Some studies suggest early and aggressive treatmentof forearm deformity to avoid deformity progression anddysfunction [12, 28–30]. Ahmed et al. suggested thatearly intervention is vital to achieve natural reduction of
the radial head [13]. According to Peterson, preventing
progressive deformities and dysfunction should be theprimary goal [28]. Our findings support early surgery forpatients with radial head dislocation, and surgery before

the age of 10 can better correct the forearm deformity,
probably due to robust bone remodeling.
Some studies have shown a high risk of re-dislocationof the radial head in younger patients [12, 16, 31]. Recurrence of ulnar shortening was also found in younger
patients with MHE [29]. Some authors recommend
delaying surgery to avoid recurrence [8, 31, 32]. Akita
et al. considered that forearm deformities are unrelated to function and no longer recommend corrective
procedures to prevent functional impairment. In theirstudy, long-term follow-up (13 years) showed that children who had early surgery continued to relapse [18].
Some authors recommend overcorrection of the ulna by
5 to 10 mm in patients with skeletal immaturity to prevent recurrence. Pritchett reported the results of ulna
lengthening in 10 forearms. He recommended excessive

Wang et al. BMC Pediatrics(2024) 24:585

Page 9 of 10

Table 4 Functional assessment of forearms without dislocationof radial head

Table 5 Functional assessment of forearms with dislocation ofradial head

Preoperative* Last Follow-up* Difference*

Preoperative* Last Follow-up* Difference*

P Value

Forearm pronation
The J-N

Forearm pronation

66.00(±4.34)

79.89(±4.99)-13.87(±6.45)

0.000*The J-D

40.22(±7.72)

68.86(±7.03)-28.65(±7.33)

0.000*The S-N 64.25(±11.29)

78.25(±7.80)-14.00(±5.48)

0.014*The S-D 37.56(±6.27)

62.44(±4.30)-24.88(±4.57)

0.000*

P’ Value

0.667

0.974

P’ Value

0.028*

0.198

77.50(±5.88)

82.50(±4.31)-5.00(±6.39)

0.063

The J-D

65.00(±8.06)

78.96(±5.78)-13.95(±5.36)

0.000*The S-N 78.50(±3.11)

83.00(±4.97)-4.50(±3.41)

0.078

The S-D 66.22(±6.70)

76.89(±5.01)-10.67(±4.66)

0.000*

P’ Value

0.860

0.888

P’ Value

0.410

0.166

130.50(±3.96)

134.00(±5.68)-3.50(±3.46)

0.064

The J-D

120.00(±10.79)

134.18(±6.57)-14.18(±11.27) 0.002*

The S-N 131.33(±2.45)

138.75(±6.65)-7.43(±7.08)

0.127

The S-D 114.56(±3.97)

131.33(±4.74)-16.78(±4.15)

P’ Value

0.224

0.215

P’ Value

0.291

0.522

0.13(±8.69)

0.63(±8.23)-0.50(±3.51)

0.699

The J-D-3.55(±6.33)

2.18(±6.35)-5.73(±9.02)

0.062

The S-N -3.75(±8.18)

0.25(±4.11)-4.00(±4.55)

0.177

The S-D -4.89(±9.57)-0.33(±4.95)-4.56(±6.73)

0.077*

P’ Value

0.934

0.168

P’ Value

0.345

0.535

50.88(±18.15)

34.88(±6.33)

16.00(±13.05) 0.010*

The J-D

47.82(±13.95)

33.36(±6.19)

14.46(±9.98)

0.001*The S-N 50.00(±14.05)

35.75(±9.78)

14.25(±4.99)

The S-D 47.56(±10.88)

33.67(±5.27)

13.89(±7.25)

0.000*

P’ Value

0.853

0.805

P’ Value

0.909

0.889

7.38(±4.56)-5.13(±2.53)

0.001*The J-D-2.45(±6.41)

5.64(±3.93)-8.09(±4.81)

0.000*The S-N 0(±4.08)

8.75(±2.50)-8.75(±4.79)

0.035*The S-D -3.00(±3.43)

2.00(±3.00)-5.00(±5.03)

0.017*

P’ Value

0.592

0.110

P’ Value

0.035*

0.178

0.699

Forearm supination
The J-N

0.708

The J-N

0.714

0.476

0.935
2.25(±3.65)
0.355

0.000*

0.711

Wrist ulnar deviation
0.011*

Wrist radial deviation
The J-N

0.170

Elbow extension

Wrist ulnar deviation
The J-N

0.721

Elbow flexion

Elbow extension
The J-N

0.416

Forearm supination

Elbow flexion*

P Value

0.964

Wrist radial deviation

denotes P < 0.05

correction in younger patients who underwent surgery
before bone maturity because of the higher tendency forrecurrence in younger patients [33]. However, complications of excessive prolongation, such as wrist impingement and ulnocarpal impaction syndrome, have also
been observed [12].
In this study, the distraction was stopped when theradial head showed reduction or positive ulnar variancereached 5 mm (the ulna was longer than the radius). At
the last telephone follow-up, we found three patientswith type IIb who had relapsed and had limited forearmfunctional activity and were all younger than 10 years
old at the time of their first surgery. The relapse may becaused by the insufficient lengthening of the ulna [27].
One patient in our study had functional activity limitations due to poor exercise after surgery. Therefore, it isalso important to encourage patients to perform proper
functional exercises after removing the external fixator.
There were certain limitations in our study. It was a retrospective case review, and the sample size was relatively
small. A control group of non-operative patients is not

*

0.821

denotes P <0.05

included in this study. In addition, follow-up until skeletal maturity is not available.

Conclusions
In conclusion, gradual ulna lengthening can effectively
improve the function and radiographic results of forearm
deformity in HME patients. For patients with radial headdislocation, early surgery can achieve better results. For
patients not associated with radial head dislocation, we
recommend regular follow-up and surgical treatment after
10 years of age.
Abbreviations
HME	Hereditary multiple exostosis
UL	Ulnar length
UV	Ulnar variance
RB/RL	The percentage of radial bowing
RAA​	Radio articular angle
CS	Carpal slip
Acknowledgements
Not applicable.

Wang et al. BMC Pediatrics(2024) 24:585

Authors’ contributions
S W, P H and J L designed the review; S W and B H performed the literaturesearches; S W, P H, J L and ML acquired the data; S W performed the data
analysis; SW, B H and YHW prepared and finished the manuscript; P H and J
L reviewed the manuscript; S W, P H, J L, B H and BM supervised manuscript
drafting and determined the final draft. PH and YHW are in charge of thelanguage polishing and the grammar revision. All authors reviewed andapproved the final version of the manuscript.
Funding
This work was supported by the Surface Project of Technical Innovation Special Project of Hubei Province (Project number [2021CFB591]).
Availability of data and materials
The datasets used and/or analyzed during the current study available from thecorresponding author on reasonable request.

Declarations
Ethics approval and consent to participate
The studies involving human participants were reviewed and approved by the
Ethics Committee of Tongji Medical College, Huazhong University of Scienceand Technology (ORG No: IORG0003571). Written informed consent was
obtained from individual or guardian participants.
Consent for publication
Not applicable.
Competing interests
The authors declare no competing interests.
Author details
1
Department of Orthopaedics, Union Hospital, Tongji Medical College,
Huazhong University of Science and Technology, Wuhan, Hubei Province
430022, China. 2 Department of Obstetrics and Gynecology, Tongji Hospital,
Huazhong University of Science and Technology, Wuhan 430022, Hubei
Province, China. 3 Chitungwiza Central Hospital, P.O BOX CZA 245, Zengeza,
Chitungwiza, Zimbabwe.
Received: 15 November 2023 Accepted: 6 September 2024

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