
==== Front
BMC Pediatr
BMC Pediatr
BMC Pediatrics
1471-2431
BioMed Central London

5063
10.1186/s12887-024-05063-9
Research
Ulnar lengthening for children with forearm deformity from hereditary multiple exostoses: a retrospective study from a tertiary medical center
Wang Shuo 1
Herman Bomansaan 1
Wu Yiheng 2
Lei Ming 1
Mutasa Blessing 3
Hong Pan hongpan2013@foxmail.com

1
Li Jin lijinwhxh2003@foxmail.com

1
1 grid.33199.31 0000 0004 0368 7223 Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei Province 430022 China
2 grid.33199.31 0000 0004 0368 7223 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
16 9 2024
16 9 2024
2024
24 58515 11 2023
6 9 2024
© The Author(s) 2024
2024
https://creativecommons.org/licenses/by-nc-nd/4.0/ 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 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 you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. 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://creativecommons.org/licenses/by-nc-nd/4.0/.
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 head dislocation, we found significant improvement in forearm, wrist function and elbow flexion (p < 0.05). For the patients with 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
Surface Project of Technical Innovation Special Project of Hubei Province2021CFB591 2021CFB591 2021CFB591 2021CFB591 2021CFB591 2021CFB591 2021CFB591 issue-copyright-statement© BioMed Central Ltd., part of Springer Nature 2024
==== Body
pmcBackground

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 the metaphysis of the long bone and can cause growth disorders and deformities [1, 3]. Forearm deformities are reported 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 radial bowing [1, 2, 4–6]. Patients with HME usually come to the hospital with local pain, functional limitations and appearance abnormalities.Fig. 1 Masada classification of the forearm osteochondroma

The purpose of surgical intervention is to correct the skeletal deformity, reduce the dislocation of the radial head 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 patients with this condition receiving ulnar osteotomy and lengthening, and patients at different age groups were compared. We aimed to evaluate the effect of ulnar osteotomy lengthening in patients of different ages and provide insights into the optional surgical timing.

Methods

Patients

In all, from July 2014 to September 2020, 52 children with forearm deformities from HME were admitted to our hospital. Finally, 35 patients (40 forearms), including 22 boys and 13 girls, were retrospectively reviewed, see Fig. 2. All patient information was obtained from the hospital database. The study was approved by the Ethics Committee of Tongji Medical College, Huazhong University of Science and Technology.Fig. 2 Flowchart of patient selection

Grouping criteria

The patients were grouped according to the status of radial head dislocation into the dislocation group and the 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 head dislocation (The J-D group), (2) Junior without radial head dislocation (The J-N group), (3) senior with radial head 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 articular angle of > 30 degrees, (3) a carpal slip of > 60% (Fig. 5), (4) dislocation of the radial head, (5) limitation of 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 than exostosis 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 location for osteotomy was the proximal one-third to one-fourth of 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.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)

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 conducted in the second week, 1 month and every 1 month after. The increase in the ulna axis and degree of callus at the osteotomy region could be monitored by X-ray. Radiological presentations of a 7-year-old boy with HME with a 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 (the 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 to maintain the length until the bone union was achieved.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)

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 the younger groups. Functional results include the pronation and supination of the forearm, the flexion and extension of the elbow, wrist ulnar deviation and wrist radial deviation.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 ulnar side of a continuation of the linear axis of the forearm)

Statistical analysis

Statistical analysis was performed with SPSS statistical software (version 25.0; SPSS, Chicago, IL, USA). Continuous variables were summarized as the mean and the standard deviation (SD). The parametric Kolmogorov-Smirnov test was used to check for normal distribution of the data. A matched-sample T-test was used for functional and imaging indicators before surgery and at the last 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 for nominal variables. The level of significance was set at a p-value < 0.05.

Results

Study population

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 head dislocation. 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. Table 1 The demographic characteristics

	Number/Mean(±SD)	Percentage（%）	
Sex	
 Boys	22	62.9	
 Girls	13	37.1	
Side	
 Right	11	31.4	
 Left	19	54.3	
 Bilateral	5	14.3	
The junior group(N/D)	23(12/11)	57.5	
The senior group(N/D)	17(8/9)	42.5	
Modified classification	
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)		
The junior group(y≤10); The senior group(y＞10)

N:without radial head dislocation

D:with radial head dislocation

SD Standard deviation

The junior groups

In the J-N group, the average UV decreased from 0.53±0.23cm to -0.04±0.45cm (p = 0.01). Forearm 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 values of 0.003 and 0.031, respectively, which were statistically significant. 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 from 54.12±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 values of 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).

Compare

The mean UL was significantly improved after surgery in four Groups (P＜0.05). For patients without dislocation, there was no significant difference in imaging and functional improvement between the younger and older groups. For patients with radial head dislocation, the radial 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 preoperative and 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 with radial 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 the younger 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 in groups 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. Table 2 Radiographic outcomes in the patients without radial head dislocation

	Preoperativea	Last Follow-upa	Differencea	P Value	
UL	
 The J-N	12.95（±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		
UV	
 The J-N	0.53（±0.23）	-0.04（±0.45）	0.57（±0.53）	0.019*	
 The S-N	0.47（±025）	0.13（±0.29）	0.34（±0.23）	0.062	
 P’ Value	0.683	0.511	0.434		
%RB	
 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		
RAA	
 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		
CS	
 The J-N					
 The S-N	54.12（22.01）	40.24（±14.12）	15.24（±8.02）	0.039*	
 P’ Value					
The S-N Group consists of patients older than 10 years without radial head dislocation（n=8）

The J-N Group consists of patients aged 10 years or less without radial head dislocation（n=12）

UL Ulnar lengthening, UV Ulnar variance, RB Radial bowing, RAA Radial articular angle, CS Carpal slip, P data between the pre-op and the last follow-up; P’ data between the junior group and the senior group

aThe values are given as the mean and the standard deviation

*denotes P < 0.05

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

Table 3 Radiographic outcomes in the patients with radial head dislocation

	Preoperativea	Last Follow-upa	Differencea	P Value	
UL	
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		
CS	
The J-D					
The S-D	57.15（±18.12）	40.42（±18.07）	17.67（±12.10）	0.003*	
P’ Value					
The J-D Group consists of patients aged 10 years or less with radial head dislocation (n=11)

The S-D Group consists of patients older than 10 years with radial head dislocation (n=9)

aThe values are given as the mean and the standard deviation

*denotes P <0.05

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

Table 4 Functional assessment of forearms without dislocation of radial head

	Preoperative*	Last Follow-up*	Difference*	P Value	
Forearm pronation	
 The J-N	66.00(±4.34)	79.89(±4.99)	-13.87(±6.45)	0.000*	
 The S-N	64.25(±11.29)	78.25(±7.80)	-14.00(±5.48)	0.014*	
 P’ Value	0.699	0.667	0.974		
Forearm supination	
 The J-N	77.50(±5.88)	82.50(±4.31)	-5.00(±6.39)	0.063	
 The S-N	78.50(±3.11)	83.00(±4.97)	-4.50(±3.41)	0.078	
 P’ Value	0.708	0.860	0.888		
Elbow flexion	
 The J-N	130.50(±3.96)	134.00(±5.68)	-3.50(±3.46)	0.064	
 The S-N	131.33(±2.45)	138.75(±6.65)	-7.43(±7.08)	0.127	
 P’ Value	0.714	0.224	0.215		
Elbow extension	
 The J-N	0.13(±8.69)	0.63(±8.23)	-0.50(±3.51)	0.699	
 The S-N	-3.75(±8.18)	0.25(±4.11)	-4.00(±4.55)	0.177	
 P’ Value	0.476	0.934	0.168		
Wrist ulnar deviation	
 The J-N	50.88(±18.15)	34.88(±6.33)	16.00(±13.05)	0.010*	
 The S-N	50.00(±14.05)	35.75(±9.78)	14.25(±4.99)	0.011*	
 P’ Value	0.935	0.853	0.805		
Wrist radial deviation	
 The J-N	2.25(±3.65)	7.38(±4.56)	-5.13(±2.53)	0.001*	
 The S-N	0(±4.08)	8.75(±2.50)	-8.75(±4.79)	0.035*	
 P’ Value	0.355	0.592	0.110		
*denotes P < 0.05

Table 5 Functional assessment of forearms with dislocation of radial head

	Preoperative*	Last Follow-up*	Difference*	P Value	
Forearm pronation	
 The J-D	40.22(±7.72)	68.86(±7.03)	-28.65(±7.33)	0.000*	
 The S-D	37.56(±6.27)	62.44(±4.30)	-24.88(±4.57)	0.000*	
 P’ Value	0.416	0.028*	0.198		
Forearm supination	
 The J-D	65.00(±8.06)	78.96(±5.78)	-13.95(±5.36)	0.000*	
 The S-D	66.22(±6.70)	76.89(±5.01)	-10.67(±4.66)	0.000*	
 P’ Value	0.721	0.410	0.166		
Elbow flexion	
 The J-D	120.00(±10.79)	134.18(±6.57)	-14.18(±11.27)	0.002*	
 The S-D	114.56(±3.97)	131.33(±4.74)	-16.78(±4.15)	0.000*	
 P’ Value	0.170	0.291	0.522		
Elbow extension	
 The J-D	-3.55(±6.33)	2.18(±6.35)	-5.73(±9.02)	0.062	
 The S-D	-4.89(±9.57)	-0.33(±4.95)	-4.56(±6.73)	0.077*	
 P’ Value	0.711	0.345	0.535		
Wrist ulnar deviation	
 The J-D	47.82(±13.95)	33.36(±6.19)	14.46(±9.98)	0.001*	
 The S-D	47.56(±10.88)	33.67(±5.27)	13.89(±7.25)	0.000*	
 P’ Value	0.964	0.909	0.889		
Wrist radial deviation	
 The J-D	-2.45(±6.41)	5.64(±3.93)	-8.09(±4.81)	0.000*	
 The S-D	-3.00(±3.43)	2.00(±3.00)	-5.00(±5.03)	0.017*	
 P’ Value	0.821	0.035*	0.178		
*denotes P <0.05

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 three patients in the J-D group who had relapsed. The main manifestations of recurrence were tumor growth and limited functional activities. One case of ulnar nonunion was also found. No postoperative impingement symptoms were observed in any of the wrists.

Discussion

Gradual ulna lengthening can effectively improve the function and radiographic results of forearm deformity in HME patients. For patients with radial head dislocation, 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 no radial 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 through the distal radioulnar joint and interosseous membrane reduces the radial head and contributes to the improvement in the RB [12–14]. Hsu et al., in their study, observed similar results in patients (≤ 10 years of 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 the deformity [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 radiological and functional results after surgery. Many studies have reported 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 of ulnar 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 the proximal oblique cord [24]. The tension of the interosseous membrane is conducive to reducing the radius head during the elongation process [20]. Subsequently, the ulna 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, many studies have applied unilateral external fixators to treat forearm deformities caused by HME and achieved good results [10, 11, 25, 26]. In this study, we used a unilateral external fixator to extend the ulna. During the follow-up, we found that due to the advantages of small size and easy postoperative care, most patients said the impact on their daily lives was acceptable. Also, when compared with 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 patients in 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 head dislocation, both groups showed significant improvement in motor function except elbow flexion. However, significant improvement in radial malformations was found 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 treatment of forearm deformity to avoid deformity progression and dysfunction [12, 28–30]. Ahmed et al. suggested that early intervention is vital to achieve natural reduction of the radial head [13]. According to Peterson, preventing progressive deformities and dysfunction should be the primary goal [28]. Our findings support early surgery for patients 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-dislocation of 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 their study, 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 correction in younger patients who underwent surgery before bone maturity because of the higher tendency for recurrence 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 the radial head showed reduction or positive ulnar variance reached 5 mm (the ulna was longer than the radius). At the last telephone follow-up, we found three patients with type IIb who had relapsed and had limited forearm functional activity and were all younger than 10 years old at the time of their first surgery. The relapse may be caused 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 is also 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 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 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.

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.

Authors’ contributions

S W, P H and J L designed the review; S W and B H performed the literature searches; 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 the language polishing and the grammar revision. All authors reviewed and approved 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 the corresponding 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 Science and 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.

Publisher’s note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Shuo Wang, Bomansaan Herman and Yiheng Wu contributed equally to this work.
==== Refs
References

1. Schmale GA Conrad EU 3rd Raskind WH The natural history of hereditary multiple exostoses J Bone Joint Surg Am 1994 76 7 986 992 10.2106/00004623-199407000-00005 8027127
Schmale GA, Conrad EU 3rd, Raskind WH. The natural history of hereditary multiple exostoses. J Bone Joint Surg Am. 1994;76(7):986–92.8027127 10.2106/00004623-199407000-00005
2. Zheng C Han H Cao Y Older age and multi-joint external fixator are two risk factors of complications in ulnar lengthening in children with hereditary multiple exostosis J Orthop Surg Res 2020 15 1 555 10.1186/s13018-020-02080-z 33228698
Zheng C, Han H, Cao Y. Older age and multi-joint external fixator are two risk factors of complications in ulnar lengthening in children with hereditary multiple exostosis. J Orthop Surg Res. 2020;15(1):555.33228698 10.1186/s13018-020-02080-z
3. Burgess RC Cates H Deformities of the forearm in patients who have multiple cartilaginous exostosis J Bone Joint Surg Am 1993 75 1 13 18 10.2106/00004623-199301000-00003 8419382
Burgess RC, Cates H. Deformities of the forearm in patients who have multiple cartilaginous exostosis. J Bone Joint Surg Am. 1993;75(1):13–8.8419382 10.2106/00004623-199301000-00003
4. Masada K Operations for forearm deformity caused by multiple osteochondromas J Bone Joint Surg Br 1989 71 1 24 29 10.1302/0301-620X.71B1.2914999 2914999
Masada K, et al. Operations for forearm deformity caused by multiple osteochondromas. J Bone Joint Surg Br. 1989;71(1):24–9.2914999 10.1302/0301-620X.71B1.2914999
5. Canizares MF, Wall LB, Van Heest A, et al. Reliability of the Masada Classification for Forearm Involvement in Patients With Hereditary Multiple Osteochondromas (HMO). J Pediatr Orthop. 2023;43(1):e60–6.
6. Huang P Zhu L Ning B Forearm deformity and radial head dislocation in pediatric patients with hereditary multiple exostoses: a prospective study using proportional ulnar length as a scale to lengthen the shortened Ulna J Bone Joint Surg Am 2020 102 12 1066 1074 10.2106/JBJS.19.01444 32221177
Huang P, Zhu L, Ning B. Forearm deformity and radial head dislocation in pediatric patients with hereditary multiple exostoses: a prospective study using proportional ulnar length as a scale to lengthen the shortened Ulna. J Bone Joint Surg Am. 2020;102(12):1066–74.32221177 10.2106/JBJS.19.01444
7. Li Y Identification of risk factors affecting bone formation in gradual ulnar lengthening in children with hereditary multiple exostoses: a retrospective study Med (Baltim) 2019 98 5 e14280 10.1097/MD.0000000000014280
Li Y, et al. Identification of risk factors affecting bone formation in gradual ulnar lengthening in children with hereditary multiple exostoses: a retrospective study. Med (Baltim). 2019;98(5):e14280.10.1097/MD.0000000000014280
8. Beutel BG Klifto CS Chu A Timing of forearm deformity correction in a child with multiple hereditary exostosis Am J Orthop (Belle Mead NJ) 2014 43 9 422 425 25251529
Beutel BG, Klifto CS, Chu A. Timing of forearm deformity correction in a child with multiple hereditary exostosis. Am J Orthop (Belle Mead NJ). 2014;43(9):422–5.25251529
9. Noonan KJ Evaluation of the forearm in untreated adult subjects with multiple hereditary osteochondromatosis J Bone Joint Surg Am 2002 84 3 397 403 10.2106/00004623-200203000-00010 11886909
Noonan KJ, et al. Evaluation of the forearm in untreated adult subjects with multiple hereditary osteochondromatosis. J Bone Joint Surg Am. 2002;84(3):397–403.11886909 10.2106/00004623-200203000-00010
10. Demir B Single-stage treatment of complete dislocation of radial head and forearm deformity using distraction osteogenesis in paediatric patients having multiple cartilaginous exostosis Arch Orthop Trauma Surg 2011 131 9 1195 1201 10.1007/s00402-011-1261-1 21298437
Demir B, et al. Single-stage treatment of complete dislocation of radial head and forearm deformity using distraction osteogenesis in paediatric patients having multiple cartilaginous exostosis. Arch Orthop Trauma Surg. 2011;131(9):1195–201.21298437 10.1007/s00402-011-1261-1
11. D’Ambrosi R Gradual ulnar lengthening in children with multiple exostoses and radial head dislocation: results at skeletal maturity J Child Orthop 2016 10 2 127 133 10.1007/s11832-016-0718-8 26910403
D’Ambrosi R, et al. Gradual ulnar lengthening in children with multiple exostoses and radial head dislocation: results at skeletal maturity. J Child Orthop. 2016;10(2):127–33.26910403 10.1007/s11832-016-0718-8
12. Vogt B Reconstruction of forearm deformity by distraction osteogenesis in children with relative shortening of the ulna due to multiple cartilaginous exostosis J Pediatr Orthop 2011 31 4 393 401 10.1097/BPO.0b013e31821a5e27 21572277
Vogt B, et al. Reconstruction of forearm deformity by distraction osteogenesis in children with relative shortening of the ulna due to multiple cartilaginous exostosis. J Pediatr Orthop. 2011;31(4):393–401.21572277 10.1097/BPO.0b013e31821a5e27
13. Ahmed A Gradual ulnar lengthening by an Ilizarov ring fixator for correction of Masada IIb forearm deformity without tumor excision in hereditary multiple exostosis: preliminary results J Pediatr Orthop B 2019 28 1 67 72 10.1097/BPB.0000000000000514 29995654
Ahmed A. Gradual ulnar lengthening by an Ilizarov ring fixator for correction of Masada IIb forearm deformity without tumor excision in hereditary multiple exostosis: preliminary results. J Pediatr Orthop B. 2019;28(1):67–72.29995654 10.1097/BPB.0000000000000514
14. Ip D Reconstruction of forearm deformities in multiple cartilaginous exostoses J Pediatr Orthopaedics-Part B 2003 12 1 17 21
Ip D, et al. Reconstruction of forearm deformities in multiple cartilaginous exostoses. J Pediatr Orthopaedics-Part B. 2003;12(1):17–21.
15. Hsu PJ Less is more: ulnar lengthening alone without radial corrective osteotomy in forearm deformity secondary to hereditary multiple exostoses J Clin Med 2019 8 11 1765 10.3390/jcm8111765 31652824
Hsu PJ, et al. Less is more: ulnar lengthening alone without radial corrective osteotomy in forearm deformity secondary to hereditary multiple exostoses. J Clin Med. 2019;8(11):1765.31652824 10.3390/jcm8111765
16. Arms DM Management of forearm deformity in multiple hereditary osteochondromatosis J Pediatr Orthop 1997 17 4 450 454 10.1097/01241398-199707000-00007 9364381
Arms DM, et al. Management of forearm deformity in multiple hereditary osteochondromatosis. J Pediatr Orthop. 1997;17(4):450–4.9364381 10.1097/01241398-199707000-00007
17. Shin EK Jones NF Lawrence JF Treatment of multiple hereditary osteochondromas of the forearm in children: a study of surgical procedures J Bone Joint Surg Br 2006 88 2 255 260 10.1302/0301-620X.88B2.16794 16434534
Shin EK, Jones NF, Lawrence JF. Treatment of multiple hereditary osteochondromas of the forearm in children: a study of surgical procedures. J Bone Joint Surg Br. 2006;88(2):255–60.16434534 10.1302/0301-620X.88B2.16794
18. Akita S Long-term results of surgery for forearm deformities in patients with multiple cartilaginous exostoses J Bone Joint Surg Am 2007 89 9 1993 1999 10.2106/00004623-200709000-00015 17768197
Akita S, et al. Long-term results of surgery for forearm deformities in patients with multiple cartilaginous exostoses. J Bone Joint Surg Am. 2007;89(9):1993–9.17768197 10.2106/00004623-200709000-00015
19. Song SH Modified Ilizarov technique for the treatment of forearm deformities in multiple cartilaginous exostoses: case series and literature review J Hand Surg Eur Vol 2013 38 3 288 296 10.1177/1753193412450651 22719009
Song SH, et al. Modified Ilizarov technique for the treatment of forearm deformities in multiple cartilaginous exostoses: case series and literature review. J Hand Surg Eur Vol. 2013;38(3):288–96.22719009 10.1177/1753193412450651
20. Lu Y Distraction osteogenesis at the proximal third of the ulna for the treatment of Masada type I/IIb deformities in children with hereditary multiple exostoses: a retrospective review of twenty cases Int Orthop 2022 46 12 2877 2885 10.1007/s00264-022-05551-6 36087118
Lu Y, et al. Distraction osteogenesis at the proximal third of the ulna for the treatment of Masada type I/IIb deformities in children with hereditary multiple exostoses: a retrospective review of twenty cases. Int Orthop. 2022;46(12):2877–85.36087118 10.1007/s00264-022-05551-6
21. Ishikawa J Tumor location affects the results of simple excision for multiple osteochondromas in the forearm J Bone Joint Surg Am 2007 89 6 1238 1247 10.2106/00004623-200706000-00012 17545427
Ishikawa J, et al. Tumor location affects the results of simple excision for multiple osteochondromas in the forearm. J Bone Joint Surg Am. 2007;89(6):1238–47.17545427 10.2106/00004623-200706000-00012
22. Hill RA Forearm lengthening by distraction osteogenesis in children: a report of 22 cases J Bone Joint Surg Br 2011 93 11 1550 1555 10.1302/0301-620X.93B11.27538 22058310
Hill RA, et al. Forearm lengthening by distraction osteogenesis in children: a report of 22 cases. J Bone Joint Surg Br. 2011;93(11):1550–5.22058310 10.1302/0301-620X.93B11.27538
23. El-Sobky TA Current paediatric orthopaedic practice in hereditary multiple osteochondromas of the forearm: a systematic review Sicot J 2018 4 10 10.1051/sicotj/2018002 29565244
El-Sobky TA, et al. Current paediatric orthopaedic practice in hereditary multiple osteochondromas of the forearm: a systematic review. Sicot J. 2018;4:10.29565244 10.1051/sicotj/2018002
24. Noda K Interosseous membrane of the forearm: an anatomical study of ligament attachment locations J Hand Surg Am 2009 34 3 415 422 10.1016/j.jhsa.2008.10.025 19211201
Noda K, et al. Interosseous membrane of the forearm: an anatomical study of ligament attachment locations. J Hand Surg Am. 2009;34(3):415–22.19211201 10.1016/j.jhsa.2008.10.025
25. Zhang R Hinge positioning method of Ilizarov apparatus in correcting radial head luxation caused by multiple hereditary exostoses Jt Dis Relat Surg 2022 33 1 40 50 10.52312/jdrs.2022.502 35361079
Zhang R, et al. Hinge positioning method of Ilizarov apparatus in correcting radial head luxation caused by multiple hereditary exostoses. Jt Dis Relat Surg. 2022;33(1):40–50.35361079 10.52312/jdrs.2022.502
26. Li Y Gradual ulnar lengthening in Masada type I/IIb deformity in patients with hereditary multiple osteochondromas: a retrospective study with a mean follow-up of 4.2 years J Orthop Surg Res 2020 15 1 594 10.1186/s13018-020-02137-z 33298090
Li Y, et al. Gradual ulnar lengthening in Masada type I/IIb deformity in patients with hereditary multiple osteochondromas: a retrospective study with a mean follow-up of 4.2 years. J Orthop Surg Res. 2020;15(1):594.33298090 10.1186/s13018-020-02137-z
27. Malot R Role of hybrid monolateral fixators in managing humeral length and deformity correction Acta Orthop 2013 84 3 280 285 10.3109/17453674.2013.786636 23506166
Malot R, et al. Role of hybrid monolateral fixators in managing humeral length and deformity correction. Acta Orthop. 2013;84(3):280–5.23506166 10.3109/17453674.2013.786636
28. Peterson HA Deformities and problems of the forearm in children with multiple hereditary osteochondromata J Pediatr Orthop 1994 14 1 92 100 10.1097/01241398-199401000-00019 8113381
Peterson HA. Deformities and problems of the forearm in children with multiple hereditary osteochondromata. J Pediatr Orthop. 1994;14(1):92–100.8113381 10.1097/01241398-199401000-00019
29. Fogel GR Management of deformities of the forearm in multiple hereditary osteochondromas J Bone Joint Surg Am 1984 66 5 670 680 10.2106/00004623-198466050-00004 6725315
Fogel GR, et al. Management of deformities of the forearm in multiple hereditary osteochondromas. J Bone Joint Surg Am. 1984;66(5):670–80.6725315 10.2106/00004623-198466050-00004
30. Scheider P Ganger R Farr S Age-related outcomes and complications of osteodistraction in the pediatric upper extremity: a large retrospective single-center study of 61 cases J Pediatr Orthop 2022 42 2 e181 7 10.1097/BPO.0000000000002013 34799541
Scheider P, Ganger R, Farr S. Age-related outcomes and complications of osteodistraction in the pediatric upper extremity: a large retrospective single-center study of 61 cases. J Pediatr Orthop. 2022;42(2):e181–7.34799541 10.1097/BPO.0000000000002013
31. Abe M Lengthening of the forearm by callus distraction J Hand Surg (Edinb Scotl) 1996 21 2 151 163 10.1016/S0266-7681(96)80090-8
Abe M, et al. Lengthening of the forearm by callus distraction. J Hand Surg (Edinb Scotl). 1996;21(2):151–63.10.1016/S0266-7681(96)80090-8
32. Ham J Multiple osteochondromas (MO) in the forearm: a 12-year single-centre experience Strategies Trauma Limb Reconstr 2016 11 3 169 175 10.1007/s11751-016-0267-1 27738974
Ham J, et al. Multiple osteochondromas (MO) in the forearm: a 12-year single-centre experience. Strategies Trauma Limb Reconstr. 2016;11(3):169–75.27738974 10.1007/s11751-016-0267-1
33. Pritchett JW Lengthening the ulna in patients with hereditary multiple exostoses J Bone Joint Surg Br 1986 68 4 561 565 10.1302/0301-620X.68B4.3488318 3488318
Pritchett JW. Lengthening the ulna in patients with hereditary multiple exostoses. J Bone Joint Surg Br. 1986;68(4):561–5.3488318 10.1302/0301-620X.68B4.3488318
