Treatment for ulnar shortening caused by osteochondromatosis

doi:10.21203/rs.3.rs-4283053/v1

Background: This study investigates treatments for ulnar shortening caused by osteochondromatosis.

Methods: A retrospective analysis was conducted on patients diagnosed with osteochondromatosis and admitted to Xiamen University Affiliated First Hospital and Fudan Zhongshan Xiamen Hospital from February 2017 to February 2022. Patients were divided into two groups based on the dislocation status of the radial head: the dislocation group and the non-dislocation group. The effectiveness of treatments was evaluated by comparing wrist movement, forearm rotation function, elbow movement, length discrepancy between the radius and ulna, presence of radial head dislocation, and carrying angle.

Results: A statistically significant difference was observed in the annual length discrepancy between the radius and ulna before and after surgery, in both the dislocation and non-dislocation groups (P < 0.05). A similar statistically significant difference was also observed in the carrying angle between the groups (P < 0.05). However, no statistically significant difference in elbow and wrist function was observed before and after surgery in either of the groups (P > 0.05).

Conclusion: Resection of osteochondroma can reduce further aggravation of ulnar deformity. Ulnar shortening contributes to secondary radial head dislocation, and ulnar lengthening can effectively treat this condition.

osteochondromatosis

ulnar shortening

radial head dislocation

lengthening

Osteochondroma or osteocartilaginous exostosis is the most common bone tumor in children^[1][2]. This condition may present as solitary or multiple lesions, with the latter termed as osteochondromatosis or hereditary multiple exostoses. Osteochondromatosis can cause ulnar shortening, leading to varying degrees of delayed ulnar development, curvature of the ulna and radius, and dislocation of the radial head, among other pathological changes. Such changes may cause forearm shortening, deformity, and joint dysfunction^[3]. At present, there are few reports on this disease both domestically and internationally, and there is no consensus on several treatment aspects, such as the impact of surgery on ulnar growth, management of secondary radial head dislocation, and the degree of joint function impairment. This article studies 32 cases involving 52 sides of the ulna, in order to provide a reasonable reference and basis for the diagnosis and treatment of this condition.

2.1 Materials

Patients with osteochondromatosis who visited Xiamen University Affiliated First Hospital and Fudan Zhongshan Xiamen Hospital from February 2017 to February 2022 were selected for this retrospective study. Patients diagnosed with osteochondromatosis, those aged under 14 years, and those with osteochondroma in the ulna were included. Patients whose epiphysis was already closed at the time of diagnosis; those with concurrent neuromuscular disorders; those whose postoperative pathological diagnosis indicated tumors other than osteochondromas; those with other congenital malformations of the forearm, such as Madelung malformation or upper ulnar radial fusion; and those who were followed up for less than two years were excluded from the study.

This retrospective study included the medical records of 32 patients (20 male and 12 female), accounting for 52 sides of the ulna that met the inclusion criteria. The age initial diagnosis in the cohort ranging from 2 to 10 (average, 4.88 ± 2.10) years, and the follow-up duration ranged from 2 to 6 (average, 1.5 ± 1.8) years. All 52 sides of the ulna underwent osteochondroma resection. In cases where radial osteochondromas were also present, they were surgically resected. Among the patients, 14 underwent ulnar osteotomy and lengthening, and 2 underwent simple ulnar osteotomy and correction.

2.2 Research methodology

At each follow-up, the age, wrist range of motion, forearm rotation function, elbow range of motion, length discrepancy between the radius and ulna, presence of radial head dislocation, and carrying angle were recorded for all patients. Considering that the distal radius and ulna in young children are not fully ossified and thus difficult to identify on X-ray images, the length discrepancy between the radius and ulna was calculated by subtracting the distance between the midpoint of the distal epiphysis and the midpoint of the proximal epiphysis from the distance between the midpoint of the ulnar epiphysis and the midpoint of the coronal process. The method used for these measurements is shown in Figure 1. The sum of the degrees of extension and flexion was recorded as the range of motion of the wrist and elbow joints, and the sum of the degrees of pronation and supination was recorded as the range of motion of the forearm. The carrying angle, which is positive in normal children and negative in cases of cubitus varus, was also measured.

Therapeutic method

After diagnosis, patients aged under 5 years were recommended to be observed by their family members until they completed 5 years, before undergoing surgical treatment. Early surgical treatment was required in two situations: 1. dislocation of the radial head and 2. the necessity of surgery in other areas of osteochondroma, with family members also opting for the removal of ulnar chondroma. Surgical treatment was considered for children aged 5 years and above who experienced the following three conditions: 1. significant appearance abnormalities, such as cubitus varus or significant local swelling; 2. limited joint function; and 3. strong demand for surgery from the parents.

Surgical method

For patients without dislocation of the radial head, only osteochondroma resection surgery was performed. If osteochondroma was also present in the radius, it was removed simultaneously. In cases involving dislocation of the radial head, a single-arm external fixation of the ulna was performed while removing the osteochondroma, followed by osteotomy at the proximal end of the ulna and ulnar lengthening after surgery. The target length for extension aimed to maintain the length discrepancy between the radius and ulna within a range of 0–5 mm. Two patients with dislocation of the radial head, whose length discrepancy between the radius and ulna was already within 5 mm, underwent direct ulnar osteotomy correction along with radial head open reduction surgery.

Data analysis

The data were divided into surgical nodes to compare the annual change in length discrepancy between the radius and ulna to evaluate whether the removal of osteochondromas affects ulnar growth. Increases in discrepancy were recorded as positive values, whereas decreases were recorded as negative values. If ulnar lengthening occurred after surgery, the discrepancy in length at the end of the ulnar lengthening was recorded, and the annual changes in length discrepancy between the radius and ulna were evaluated. Patients were divided into two groups based on the dislocation status of the radial head: the dislocation group and the non-dislocation group. For both groups, the preoperative wrist joint function, forearm rotation range, elbow joint function, length discrepancy between the radius and ulna, and carrying angle were recorded. These data were used to evaluate the impact of concurrent radial head dislocation on limb function in patients. The postoperative wrist joint function, forearm rotation function, elbow joint function, and carrying angle from the last follow-up were used as functional evaluation data. By comparing the preoperative and postoperative data of the two groups separately, the effectiveness of the surgical treatment was evaluated.

2.3 Statistical analysis

Quantitative data were represented by (x ± s) and analyzed using the t-test. Numerical data were presented in a four-grid table and analyzed using the kappa test. The SPSS version 27.0 (IBM, Armonk, NY, USA) software was used to analyze the data, with a P-value <0.05 indicating a statistically significant difference.

The annual change in the length discrepancy between the radius and ulna before and after surgery was significant. Initially, the discrepancy changed by 2.83 ± 1.28 mm annually, which reduced to 0.63 ± 0.35 mm after surgery (P < 0.05). Before surgery, the annual change in length discrepancy was greater in the dislocation group (3.44 ± 1.03 mm) compared to the non-dislocation group (2.56 ± 1.30 mm), with the difference being statistically significant (P < 0.05). After surgery, the discrepancy continued to decrease in both groups, with the dislocation group showing a change of 0.94 ± 0.37 mm and the non-dislocation group showing a change of 0.49 ± 0.25 mm, both of which were statistically significant differences (P < 0.05).

A detailed preoperative comparison between the radial head dislocation group and the non-dislocation group is provided in Table 1. It reveals statistically significant differences in the annual change in length discrepancy between the radius and ulna and the carrying angle. However, no statistically significant differences were found in wrist joint function, forearm rotation function, and elbow joint function between the two groups.

The preoperative and postoperative details of the non-dislocation group are compared in Table 2. It highlights that the annual change in length discrepancy between the radius and ulna was statistically significant. Conversely, no statistically significant differences were observed in the carrying angles, wrist joint function, forearm rotation function, and elbow joint function.

A detailed comparison of the preoperative and postoperative conditions for the dislocation group is provided in Table 3. It indicates that both the annual change in length discrepancy between the radius and ulna and the differences in carrying angle are statistically significant. However, no statistically significant differences were observed in wrist joint function, forearm rotation function, and elbow joint function.

Osteochondromatosis is classified as a congenital skeletal developmental abnormality, mostly showing a positive family history and autosomal dominant inheritance^[4][5]. This condition is usually caused by mutations in the EXT1, EXT2, and EXT3 genes^[6][7]. The main factors that induce osteochondromatosis are congenital embryonic defects, displacement of epiphyseal plates, residual high-quality cells in areas of bone friction, and abnormal plasticity at the metaphyseal ends, resulting in widening and continuous thickening of the metaphyseal ends, and the production of osteophytes^[8]. The lesion begins to grow outward from the metaphysis, connecting the bone marrow cavity to the osteophyte. Osteophytes are mainly composed of cancellous bone, which includes both fat and bone marrow. The surface of osteophytes is covered with cancellous bone caps of different thicknesses, with calcified cartilage present. The tumor moves towards the shaft as the bone grows, and the growth direction is consistent with the direction of muscle traction, typically away from the joint^[9]. The growth process of osteophytes is similar to that of normal bone, halting once growth stops. However, unlike solitary osteochondromas, which usually show dendritic growth and localized masses, lesions of osteochondromatosis often enlarge and may cause limb deformities. This is particularly evident when lesions occur in the ulna, often causing ulnar shortening, a condition that can progressively worsen with growth and development in some patients^[10]. Interestingly, while lesions may occur in both the ulna and radius, there have been no cases with the radius being significantly shorter than the ulna. This could be attributed to the thinner distal epiphysis of the ulna compared to that of the radius, making it more susceptible to the influence of lesions and affecting its growth ability. This study does not further explore these genetic and morphological aspects. Rather, it study focuses on the impact of ulnar shortening on limb function caused by osteochondromatosis and the effective management of this condition.

In normal individuals, owing to the presence of the olecranon of the ulna, the ulna is longer than the radius. However, the olecranon does not contribute to the length of the forearm, which is measured from the elbow joint to the wrist joint. Despite the ulna’s apparent longer length, its distal end is roughly in the same plane as the medial distal end of the radius. However, owing to incomplete ossification of the distal radius and ulna in children, it is difficult to accurately determine the position of the distal radius and ulna through an X-ray. Therefore, this study used the midpoint of the distal epiphyseal line as the measurement point. Similarly, the incomplete ossification of the lateral condyle of the humerus and the radial head makes it difficult to clearly distinguish the position of the proximal articular surface of the radius. Therefore, the midpoint of the epiphyseal line of the radial head and the coronoid process of the ulna were used as measurement points.

In normal children, the distance between the midpoint of the distal and proximal epiphyseal lines of the radius is almost equal to the distance from the midpoint of the distal ulna epiphyseal line to the coronoid process of the ulna, as shown in Figure 1. Therefore, in the study, the length discrepancy between the radius and ulna, defined as the distance between the midpoint of the distal and proximal epiphyseal lines of the radius minus the distance from the midpoint of the distal ulnar epiphyseal line to the coronoid process of the ulna, was used to reflect the impact of osteochondromatosis on the forearm, where the condition often shows growth disorders in the ulna, resulting in a significantly shorter ulna compared to the normal. Such shortening can cause deformation of the distal epiphyseal line of the radius, an increase in the outward curvature of the radial arch, and dislocation of the radial head, with the latter having a significant impact on forearm function and resulting in obvious cubitus varus.

This study demonstrates that untreated lesions affect the growth rate of the ulna, increasing the length discrepancy between the radius and ulna, with an annual growth rate discrepancy of 2.83 ± 1.28 mm. After surgical resection of the lesions, the rate of increase in the length discrepancy between the radius and ulna significantly decreased. In some cases, the discrepancy tended to stabilize, while in others, it continued to grow, although at a slower rate than before. The average annual growth after resection was 0.63 ± 0.35 mm. However, no evidence suggested that the ulnar growth accelerates after resection to a point where the length discrepancy between the radius and ulna decreases. This indicates that the resection of lesions does not restore the growth rate of the ulna to normal levels, and the affected epiphyseal growth function still differs from that of normal epiphyses. Furthermore, the study found no significant difference in the wrist joint function, forearm rotation function, and elbow joint function before and after the simple resection of ulnar lesions.

In this study, a significant difference was found in the length discrepancy between the radius and ulna in individuals with radial head dislocation compared to those without. The principle of radial head dislocation caused by ulnar shortening may be that the interosseous membrane connects the radius and ulna, causing the radius to be pulled toward the proximal side by the shorter ulna, resulting in excessive pressure on the proximal end of the radius relative to the lateral condyle of the humerus, forcing the radial head to dislocate outward to adapt to the increase in radius length. This is different from radial dislocation caused by a Monteggia fracture, where there is no tearing of the annular ligament or compression of the joint capsule into the joint space. Therefore, lengthening the ulna can relieve the traction of the interosseous membrane, allowing the entire radius to move toward the distal end and the dislocated radial head to self reduce. After the reduction of the radial head, the carrying angle of the elbow joint significantly improved, and the cubitus varus was corrected. Figure 2 provides a detailed example of this phenomenon. In this study, ulnar lengthening in all cases resulted in reduction of the radial head.

Multiple studies have supported the therapeutic effect of ulnar lengthening^[11-13]. However, ulnar shortening cannot fully explain the cause of radial dislocation. There have been cases where some patients did not show significant shortening of the ulna but still experienced radial head dislocation. In such instances, dislocation was corrected through osteotomy without the need for lengthening, as detailed in Figure 3. This suggests that radial head dislocation might also be caused by ulnar deformation due to osteochondromatosis, which often manifests as an increase in the curvature of the ulna toward the dorsal and radial sides. Although ulnar lengthening on the longitudinal axis of the forearm may correct some aspects of ulnar morphology, it cannot be entirely assumed that radial head dislocation can be corrected solely by lengthening the ulna. Therefore, ulnar shortening is identified as one of the causes of radial head dislocation.

In this study, the length discrepancy between the ulna and radius in the dislocation group (20.00 ± 3.08 mm) was significant compared to the non-dislocation group (8.06 ± 2.89 mm). This suggests that a length discrepancy of more than 20 mm between the radius and ulna is a high-risk factor for radial head dislocation. Moreover, the annual increase in the length discrepancy in the dislocation group progressed faster than in the non-dislocation group, indicating that ulnar shortening is one of the important factors in radial head dislocation. Postoperative analysis still showed a quicker progression of length discrepancy in the dislocation group, which may be attributed to the fact that osteochondromatosis is a systemic disease, and patients with rapid progression are not only affected by ulnar growth disorders caused by ulnar lesions but also have abnormalities in the epiphysis themselves. Owing to the multiplanar deformation of the ulna, a good quantitative method to evaluate the specific correlation between ulnar deformation and radial head dislocation remains to be investigated.

This study found no statistically significant difference in wrist elbow joint function and forearm rotation function before and after surgery, which could be attributed to two factors. Firstly, the high elasticity of children’s ligaments may offer a compensatory mechanism to counteract the impact of ulnar shortening or radial head dislocation. A previous study suggests that for young children with radial head dislocation, ulnar radial fusion surgery can achieve good therapeutic effects^[14]. Secondly, some deformities in children require a certain time for obvious functional impairment to occur, such as non-union of humeral lateral condyle fractures and Monteggia fractures. Thus, their symptoms and functional limitations could remain unnoticed in the early stages, and may become evident several years later, when obvious functional impairment begins to appear. The proactive treatment of all cases in this study could explain the absence of notable limitations in joint mobility. In clinical practice, although no significant limitations were found in the range of motion of the joints among the affected children, some children, especially those with radial head dislocation, showed significant differences in strength and endurance during heavy load exercises compared to their healthy counterparts. However, it is difficult to get young children to cooperate with complex motor function tests, and simple muscle strength rating systems may not accurately reflect the impact on function. In addition, comparisons with the healthy side are not feasible in children with bilateral conditions. Hence, this study did not further investigate the impact of ulnar shortening on complex motor functions.

Studies have shown that ulnar growth restriction may still occur even after the resection of ulnar lesions^[15], suggesting that multiple ulnar extensions may sometimes be required. Another study suggested that if there are no serious symptoms, surgical treatment can be considered after the individual has reached skeletal maturity^[16]. This perspective is not contradictory to the findings of the current study, which observed a deceleration in the length discrepancy between the displaced radius and ulna after resection of lesions, but no accelerated growth of the ulna. While this study did not record any further shortening of the ulna leading to radial head dislocation or cubitus varus, the lack of follow-up into adulthood indicates that it is currently not possible to conclude that a single surgery alone can prevent the progression of deformities. This study only indicates that the resection of ulnar osteochondromas has a positive effect on preventing further ulnar shortening, and in cases of obvious ulnar shortening, ulnar lengthening surgeries can effectively correct deformities.

In conclusion, for children with osteochondromatosis that results in ulnar shortening, surgical removal of the osteochondroma at the distal end of the ulna can help reduce further aggravation of ulnar deformities. Ulnar shortening is one of the factors causing secondary radial head dislocation. Therefore, ulnar lengthening has a significant therapeutic effect on radial head dislocation and cubitus varus caused by obvious ulnar shortening.

Acknowledgements

None.

Funding

Not applicable.

Availability of data and materials

Not applicable.

Authors’ contributions

SW and AH were the lead authors of this manuscript. SZ, QL, LS, CW, YC and ML were contributing authors. All authors read and approved the final manuscript.

Authors’ information

AH and SZ are members of Zhongshan Hospital (Xiamen) in the Department of Plastic Surgery in Xiamen. The others are menbers of First Affiliated Hospital of Xiamen University in Department of Pediatric Orthopedics in Xiamen.

Competing interests

The authors declare that they have no competing interests.

Consent for publication

Not applicable.

Ethics approval and consent to participate

Not applicable.

Black B, Dooley J, Pyper A, et al. Multiple hereditary exostoses. An epidemiologic study of an isolated community in Manitoba. Clin Orthop Relat Res 1993(287): 212–217.
David R and Lucas M. Dahlin’s bone tumors: general aspects and data on 11,087 cases. Am J Clin Pathol 1996; 106(5): 693.
Beltrami G, Ristori G, Scoccianti G, Tamburini A, Capanna R. Hereditary multiple exostoses: a review of clinical appearance and metabolic pattern. Clin Cases Miner Bone Metab. 2016; 13(2): 110-8.
Cammarata-Scalisi F, Stock F, Avendaño A, Cozar M, Balcells S, Grinberg D. Estudio clínico y molecular en una familia con osteocondromatosis múltiple [Clinical and molecular study in a family with multiple osteochondromatosis]. Acta Ortop Mex. 2018 Mar-Apr;32(2):108-111.
Jesús Santos-Guzmán, Consuelo Cantú-Reyna, Ignacio Cano-Muñoz, Ana Karen Pulido-Ayala, Adrián Garcia. Multiple hereditary osteochondromatosis in a family. Boletín Médico Del Hospital Infantil de México (English Edition), 2016, 73( 2): 111-116.
Cook A, Raskind W, Blanton SH, et al. Genetic heterogeneity in families with hereditary multiple exostoses. Am J Hum Genet 1993; 53(1): 71-79.
Le Merrer M, Legeai-Mallet L, Jeannin PM, et al. A gene for hereditary multiple exostoses maps to chromosome 19p. Hum Mol Genet 1994; 3(5): 717–722.
Schmale GA and Raskind WH. The natural history of hereditary multiple exostoses. J Bone Joint Surg Am 1994; 76(7): 986–992.
Ha TH, Ha TMT, Nguyen Van M, Le TB, Le NTN, et al. Hereditary multiple exostoses: A case report and literature review. SAGE Open Med Case Rep. 2022 Jun 7;10: 2050313X221103732.
Gottschalk HP, Kanauchi Y, Bednar MS, Light TR. Effect of osteochondroma location on forearm deformity in patients with multiple hereditary osteochondromatosis. J Hand Surg Am. 2012 Nov;37(11):2286-93.
Tang Z.W, Cao Y.L, Liu T, Chen T, Zhang X.S. Management of forearm deformities with ulnar shortening more than 15 mm caused by hereditary multiple osteochondromas. Eur. J. Orthop. Surg. Traumatol. 2013, 23,611–618.
Vogt B, Tretow H.L, Daniilidis K, Wacker S, Bulle T.C, 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, 393-401.
Hsu PJ, Wu KW, Lee CC, Kuo KN, Chang JF, et al. Less Is More: Ulnar Lengthening Alone without Radial Corrective Osteotomy in Forearm Deformity Secondary to Hereditary Multiple Exostoses. J Clin Med. 2019 Oct 23;8(11):1765.
Waters PM. Forearm rebalancing in osteochondromatosis by radioulnar fusion. Tech Hand Up Extrem Surg. 2007 Dec;11(4):236-40.
Shin E.K, Jones N.F, Lawrence J.F. Treatment of multiple hereditary osteochondromas of the forearm in children: A study of surgical procedures. J. Bone Jt. Surg. Br. 2006, 88, 255-260.
Arms DM, Strecker WB, Manske PR, Schoenecker PL. Management of forearm deformity in multiple hereditary osteochondromatosis. J Pediatr Orthop. 1997 Jul-Aug;17(4):450-4.

Table 1. Comparison of preoperative conditions between the radial head dislocation group and the non-dislocation group

	Dislocation group	Non-dislocation group	P-value
Male	6	14	0.297
Female	4	8	0.297
Age (year)	4.00±1.79	5.27±2.11	0.110
Length discrepancy between the radius (mm)	20.00±3.08	8.06±2.89	<0.001
Carrying angle (°)	-7.19±5.15	12.22±8.49	<0.001
Extension and flexion range of wrist joint (°)	105.94±9.87	107.08±9.44	0.692
Abduction and adduction range of wrist joint (°)	64.06±8.41	63.06±8.13	0.685
Forearm rotation function (°)	167.81±8.56	169.17±7.88	0.580
Extension and flexion range of elbow joint (°)	154.38±6.55	154.17±6.71	0.918

Table 2. Comparison between preoperative and postoperative outcomes in the non-dislocation group

	Preoperative	Postoperative	P-value
Annual change of length discrepancy between the radius (mm)	2.56±1.30	0.50±0.25	<0.001
Carrying angle (°)	12.22±8.49	13.47±6.95	0.496
Extension and flexion range of wrist joint (°)	107.08±9.44	107.64±9.45	0.804
Abduction and adduction range of wrist joint (°)	64.06±8.13	62.64±8.24	0.830
Forearm rotation function (°)	169.17±7.88	170.00±8.11	0.660
Extension and flexion range of elbow joint (°)	154.17±6.71	154.58±7.11	0.799

Table 3. Comparison between preoperative and postoperative outcomes in the dislocation group

	Preoperative	Postoperative	P-value
Annual change of length discrepancy between the radius (mm)	3.44±1.03	0.94±0.37	<0.001
Carrying angle (°)	-7.19±5.15	9.69±5.62	<0.001
Extension and flexion range of wrist joint (°)	105.94±9.87	108.75±10.57	0.443
Abduction and adduction range of wrist joint (°)	64.06±8.41	65.00±7.53	0.742
Forearm rotation function (°)	167.81±8.56	170.94±6.12	0.244
Extension and flexion range of elbow joint (°)	154.38±6.55	153.75±6.95	0.795

No competing interests reported.

Treatment for ulnar shortening caused by osteochondromatosis

Status:

Version 1

Abstract

Figures

1. Background

2. Materials and Methods

3. Results

4. Discussion

5. Conclusion

Declarations

References

Tables

Additional Declarations

Status:

Version 1