Fracture fragment of the condyle determines the ramus height of the mandible in children with intracapsular condylar fractures treated conservatively

ABSTRACT This study aimed to explore and impart understanding of bone remodelling in children with intracapsular fractures treated conservatively. Records of children (less than 12 years),

who sustained intracapsular fractures and treated conservatively, were retrieved consecutively for the period of March 2011 to February 2016. Data about age, gender, date of injury, dates of

admission and discharge, mechanism of trauma, location and pattern of fracture, other mandibular fractures, treatment methods and time of review were recorded and analysed. Image dates of

pre- and post-treatments, including date of review, were also recorded. A total of 22 patients complete their follow-up and show bone remodelling process. During their follow-up, all the

displaced condylar fragments fused with the ramus stump at the displaced position. Regardless of the type of conservative procedure, both treatments cannot promote the spontaneous fracture

reduction in patients with intracapsular condylar fractures. During follow-up, the absorption of the lateral process of the condyle after the closed treatment becomes close to the

‘horizontal absorption’, until the height (or articular surface) of the lateral condylar process dropped and aligned to the articular surface of the medial process. In children with

intracapsular condylar fractures, the fracture fragment of the condyle determines the ramus height of the mandible. Closed treatment cannot restore the fracture fragment. If the height of

the fracture fragments dropped remarkably, then open reduction and rigid internal fixation become more suitable. SIMILAR CONTENT BEING VIEWED BY OTHERS A 2 YEAR FOLLOW-UP SELF-CONTROLLED

STUDY ON MORPHOLOGICAL CHANGES IN THE MUSCULOSKELETAL APPARATUS AFTER CONSERVATIVE TREATMENT OF CONDYLAR HEAD FRACTURE Article Open access 13 May 2025 THE MAGNETIC RESONANCE IMAGING

EVALUATION OF CONDYLAR NEW BONE REMODELING AFTER YANG’S TMJ ARTHROSCOPIC SURGERY Article Open access 04 March 2021 THE INFLUENCE OF WISDOM TOOTH IMPACTION AND OCCLUSAL SUPPORT ON MANDIBULAR

ANGLE AND CONDYLE FRACTURES Article Open access 16 April 2021 INTRODUCTION Mandibular condyle is a fracture that frequently occurs in younger children. It is of special consequence because

the condyle is considered a primary growth centre of the jaw1,2. Intracapsular fractures are found predominantly amongst young children and are generally treated by closed treatment. To

date, many scholars generally hold the viewpoint that the displaced medial fragment could remodel into its original position even when the medial fragment was notably displaced, and the

shortening of the ramus height had been restored according to the capacity for remodelling3. However, other scholars denied this view and considered that the reduction of the fracture does

not generally occur under closed treatment4. However, evidence is insufficient. Our previous research found that the upright position of the fracture fragments of condylar neck or base

originates from the skeleton remodelling, rather than the anatomical reduction of the deviated condylar processes5. Therefore, this study aims to explore and impart understanding of bone

remodelling in children with intracapsular fractures treated conservatively. We hypothesised that the fracture fragment of the condyle determines the ramus height of the mandible. Present

study has found that the ramus height of the mandible is determined by the height of the fracture fragments (or medial process of condyle) in children with intracapsular condylar fractures

treated by conservative treatment. In addition, this study indicates that closed treatment cannot restore the fracture fragment in children with intracapsular condylar fractures. If the

height of the fracture fragments dropped remarkably, then open reduction and rigid internal fixation become more suitable. PATIENTS AND METHODS From March 2011 to February 2016, 22 patients

(less than 12 years) with intracapsular fractures treated conservatively were reviewed retrospectively and consecutively. The institutional review board of Wuhan University approved the

protocol, survey and consent forms (approval number: HGGC-146). The study was conducted in accordance with the Helsinki declaration and national regulation on study involving humans.

Informed consent was obtained from the legal guardian(s) of all children. Records of children (less than 12 years)6,7 who sustained intracapsular fractures and treated conservatively, were

retrieved consecutively for the period of March 2011 to February 2016. Data about age, gender, date of injury, dates of admission and discharge, mechanism of trauma, location and pattern of

fracture, other mandibular fracture, treatment methods and time of review were recorded and analysed. Image dates of pre- and post-treatment, including date of review, were also recorded.

Patients or files were excluded as study subjects based on the following: (1) incomplete information (especially the radiographic data), (2) lack of follow-up data (especially the

radiographic data) and (3) intracapsular condylar fractures treated surgically. The condylar head fractures (intracapsular fractures) were divided into three portions, namely, lateral third

(type A), central third (type B), medial third fractures (type C) and comminuted fracture of condylar head (type M), as proposed by He et al.8. Patients with type A/B/C fractures were

included in the present study, whereas type M fractures were excluded because the ramus height of the mandible decreased seriously during injury. Conservative treatment of intracapsular

condylar fractures was indicated in present cases, as follows: (1) children less than 12 years, (2) intracapsular condylar fracture was not treated surgically before and/or not treated

previously in other hospital, (3) new fracture less than 3 weeks. Conservative treatment included occlusal splint combined with maxillo-mandibular traction (achieved by self-drilling

cortical bone screws) for 4 weeks, patients were asked to eat fluid diet and do functional training (practice active mouth-opening exercises) in this period. After 4 weeks, the occlusal

splint and screws were removed. Based on the exclusion criteria, 22 patients have completed their follow-up and have shown bone remodelling process. STATISTICAL ANALYSES Descriptive analysis

was performed with the SPSS software (version 19.0; SPSS, Chicago, IL). The continuous variables were reported as mean ± SD. RESULTS In the five-year records retrieved during this study, 22

young patients were found to have sustained intracapsular condylar fractures. Amongst them, 14 were boys and eight were girls with a boy/girl ratio of 1.75:1; 15 children were unilateral

and seven were bilateral. Patients with intracapsular condylar fractures ranged from 2.4 to 11 years old, with a mean age of 6.68 ± 2.36 years. The shortest time of absorption in computed

tomography scan, observed in 31st day and the longest time in 415th day (average time of 112.68 ± 82.95 days). Fall-related accidents were the most common mechanism of injury (14 patients,

63.6%), followed by motor vehicle and motorcycle accidents (five patients, 22.7%). Table 1 shows the details of young patients with intracapsular condylar fractures treated by conservative

procedures. During their follow-up, all displaced condylar fragments fused with the ramus stump at the displaced position. Regardless of the type of conservative procedure, both treatments

cannot promote the spontaneous fracture reduction in patients with intracapsular condylar fractures. During follow-up, the absorption of the lateral process of the condyle after the closed

treatment was close to the ‘horizontal absorption’ until the height (or articular surface) of the lateral condylar process dropped and aligned to the articular surface of the medial process.

Sometimes, the simultaneous occurrence of the abduction of condylar head and the displacement of the medial process (fracture fragments) inferiorly lead to the mixed vertical and horizontal

absorption. No children patients presented ankylosis of temporomandibular joint during their follow-up. Figures 1, 2, 3, 4, 5 show the detailed bone remodelling. DISCUSSION Intracapsular

condylar fractures are found predominantly amongst young children and are generally treated by conservative treatment. To date, many scholars generally hold the viewpoint that the displaced

medial fragment could remodel into its original position even when the medial fragment was notably displaced, and the shortening of the ramus height had been restored according to the

remodelling capacity. This study found that the use of any conservative method to promote spontaneous fracture reduction in patients with intracapsular condylar fractures is impossible.

During follow-up, the absorption of the lateral process of the condyle after the conservative treatment was close to the ‘horizontal absorption’, until the height (or articular surface) of

the lateral condylar process dropped and aligned to the articular surface of the medial process. These findings have an important impact on clinical practice. This discovery reminds us that

the ramus height of the mandible is determined by the height of the fracture fragments (or medial process of condyle) in children with intracapsular condylar fractures treated by closed

treatment. If the height of the fracture fragments dropped remarkably, then open reduction and rigid internal fixation may be more suitable. Therefore, further researches are needed in the

future. After the occurrence of intracapsular condylar fractures, the continued traction of the lateral pterygoid muscle results in the anteromedial displacement of the fragment in condylar

head fractures9. A previous study10 revealed that immediately after injury, nearly all intracapsular condylar fractures showed anteromedial displacement of the disc and fractured condylar

fragment. Even at 3 months after injury, all patients continued to exhibit displacement of the disc and the condylar segments. In our previous study, we found that the upright position of

the extracapsular condylar fragments originates from the remodelling of the skeleton rather than the anatomical reduction of the deviated condylar processes5. This study observed that the

use of occlusal splint (or any other conservative methods) to promote the spontaneous fracture reduction in patients with intracapsular condylar fractures is impossible because the

horizontal traction force of the lateral pterygoid muscle cannot be eliminated under those circumstances. Ellis and Throckmorton4 do not use the term ‘closed reduction’, which they believe

is a misnomer, because reduction of the fracture dose not generally occur spontaneously. Nonetheless, the removable occlusal splint11,12 is widely used because it is easy to fabricate and

comfortable for children to wear; it helps re-establish normal occlusion and allows the mandible to maintain appropriate relationship with the maxilla. In addition, it allows early

mobilisation, eating and mandibular exercises and promote haematoma resolution and tissue recovery12. They12 even stated that wearing the occlusal splint followed by regular exercises

resulted in good mandibular function and condylar remodelling in children patients; no patient had TMJ symptoms and ankylosis. In the past, most previous studies claimed successful

remodelling once the condyle head was reconstructed into an arc (or oval) shape. Thorén13 found that incomplete remodelling with a flattened or irregular surface of the condylar head

associated with deformation of the condylar neck was frequently observed after condylar fracture in childhood. However, some authors had observed that the fractured fragments resorbed

completely but with acceptable condylar remodelling14. Other authors12 showed that in children with unilateral fractures, the condyles were incompletely remodelled with relatively short and

flattened condylar heads and flattened glenoid fossa compared with the contralateral normal condyles; most of their patients (children) showed slight difference in length between the

fractured and contralateral ramus. Some patients showed condylar deformity15 and altered mandibular growth16. However, they were usually only judged by visual observation. Previous studies

cannot easily provide direct evidence to answer whether or not condylar head resorption exists. This study presents the detailed process of condylar head resorption, but more studies are

needed in the future. The horizontal absorption of the lateral process of the condyle after the closed treatment is surprising. The absorption of the residual condylar head is different from

the resorption of the lateral condylar head because of the abduction of the condylar process17. Abduction leads to the ‘vertical absorption’ until condylar head located at the concentric

position of the glenoid fossa. In the present study, the absorption of the lateral process of the condyle after the closed treatment was close to the ‘horizontal absorption’, until the

height (or articular surface) of the lateral condylar process dropped and aligned to the articular surface of the medial process. Sometimes, the simultaneous occurrence of the abduction of

condylar head and the displacement of the medial process (fracture fragments) inferiorly lead to the mixed vertical and horizontal absorption. Surprisingly, this absorption only occurs in

children and is rarely found in adults in the above situation. He et al.18 indicated that the combination of an intracapsular fracture with concomitant widening of the mandible caused the

lateral pole of the condyle or the condylar stump to become displaced laterally or superolaterally in relation to the zygomatic arch, where it fused and formed the TMJ ankylosis. Chang et

al.3 found that three of the 23 children developed TMJ ankylosis due to ramus stumps displaced laterally and made contact with the root of the zygoma. In the present study, no TMJ ankylosis

was found. The important reason is that none of our patients’ condylar stump was displaced laterally or superolaterally to the zygomatic arch post-trauma or after intervention. Clinically

over the past decades, we rarely found the occurrence of TMJ ankylosis in children with intracapsular condylar fractures in our department. Zhao et al.12 also found no patient (40 children

with condylar fractures, most children patients suffered high-neck fractures and intracapsular fractures) had TMJ symptoms and ankylosis. Therefore, we also speculate that the presence of

articular cartilage in children prevented them from developing TMJ ankylosis, in spite of the disc displaced anteromedially; whereas in adult, articular cartilage of condyle is generally

degenerated. However in present study, we didn’t use Magnetic Resonance Imaging (MRI). Therefore, we can’t assess disc displacement. Some limitations could be found in this study. First, it

is a retrospective study with small sample size. The small size reduced the power but provided the discovery unreported previously. Second, the cases were only obtained from our own hospital

(maxillofacial trauma service), some paediatric patients could be brought for care in other children’s hospital, and multicentre and more sample studies are necessary in the future.

However, our department was amongst the largest centres for patients with facial trauma in central China, and the children patients were treated consecutively with nearly no omission. Thus,

we consider our findings similar to those other large maxillofacial urban units in China. In conclusion, in children with intracapsular condylar fractures, the fracture fragment of the

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AFFILIATIONS * The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School & Hospital of

Stomatology, Wuhan University, Wuhan, People’s Republic of China Rui-cong Yang, Meng-juan Cui, Hai-Hua Zhou, Kun Lv, Rong-Tao Yang, Zhi Li & Zu-Bing Li * Department of Oral and

Maxillofacial Surgery, College and Hospital of Stomatology, Wuhan University, 237 Luoyu Road, Wuhan, 430079, Hubei, People’s Republic of China Hai-Hua Zhou, Kun Lv, Rong-Tao Yang, Zhi Li 

& Zu-Bing Li Authors * Rui-cong Yang View author publications You can also search for this author inPubMed Google Scholar * Meng-juan Cui View author publications You can also search for

this author inPubMed Google Scholar * Hai-Hua Zhou View author publications You can also search for this author inPubMed Google Scholar * Kun Lv View author publications You can also search

for this author inPubMed Google Scholar * Rong-Tao Yang View author publications You can also search for this author inPubMed Google Scholar * Zhi Li View author publications You can also

search for this author inPubMed Google Scholar * Zu-Bing Li View author publications You can also search for this author inPubMed Google Scholar CONTRIBUTIONS Conceived and designed the

experiments: R.C.Y., M.J.C., H.H.Z. Analysed the data: R.C.Y., M.J.C., H.H.Z. Wrote the paper: R.C.Y., H.H.Z. Substantial contribution to acquisition of data: H.H.Z. Critically revised

article for important intellectual content: R.C.Y., M.J.C., H.H.Z., K.L., R.T.Y., Z.L., Z.B.L. Critically reviewed the manuscript: H.H.Z. Approved the final version of the manuscript: H.H.Z.

CORRESPONDING AUTHOR Correspondence to Hai-Hua Zhou. ETHICS DECLARATIONS COMPETING INTERESTS The authors declare no competing interests. ADDITIONAL INFORMATION PUBLISHER'S NOTE

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this licence, visit http://creativecommons.org/licenses/by/4.0/. Reprints and permissions ABOUT THIS ARTICLE CITE THIS ARTICLE Yang, Rc., Cui, Mj., Zhou, HH. _et al._ Fracture fragment of

the condyle determines the ramus height of the mandible in children with intracapsular condylar fractures treated conservatively. _Sci Rep_ 12, 19924 (2022).

https://doi.org/10.1038/s41598-022-24463-4 Download citation * Received: 21 October 2021 * Accepted: 15 November 2022 * Published: 19 November 2022 * DOI:

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