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Delayed surgical treatment of orbital trapdoor fracture in paediatric patients
  1. Yun Su1,2,
  2. Qin Shen1,2,
  3. Xiaoping Bi1,2,
  4. Ming Lin1,2,
  5. Xianqun Fan1,2
  1. 1 Department of Ophthalmology, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University, School of Medicine, Shanghai, China
  2. 2 Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Shanghai, China
  1. Correspondence to Dr Xianqun Fan, Department of Ophthalmology, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University, School of Medicine, Shanghai, 200011, China; fanxq{at}; Dr Ming Lin, Department of Ophthalmology, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University, School of Medicine, Shanghai, 200011, China; linmingcn{at}


Background Trapdoor fracture is a special type of orbital blowout fracture. Although early surgery is recommended, there still remain some patients delayed by various reasons. In this study, we analysed the clinical characteristics of delayed paediatric patients, especially those with different levels of ocular motility restriction before surgery.

Methods Thirty patients (3 to 14 years old) who underwent delayed surgery for trapdoor fractures between January 2008 and September 2016 were enrolled. Their demographics, causes of injury and delay, clinical features, imaging data and follow-up information were collected.

Results Muscular entrapment was found in 17 patients (group A) and soft-tissue entrapment in 13 patients (group B). 12 (7 in group A) presented with severe motility restriction and 18 (10 in group A) with mild restriction before surgery. 41.7% with severe restriction recovered after surgery, compared with 83.3% with mild restriction. Four (23.7%) in group A (all with severe restriction) and six (46.2%) in group B (half with severe restriction) presented with persistent diplopia.

Conclusions Long recovery time and a high percentage of persistent diplopia are the main problems of delayed trapdoor fracture in children. A prompt surgery within 48 hours is strongly recommended in patients with muscular entrapment even if an urgent treatment is hard to achieve. So are patients with soft-tissue entrapment and significant motility restriction. In the other patients without such indications, even though some recovery might be possible in the long term, a prompt surgery right after diagnosis is still preferable regardless of the entrapped contents.

  • Orbital fracture
  • trapdoor fracture
  • pediatric
  • entrapment

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Trapdoor fracture is a special type of orbital blowout fracture mainly found in children due to their greater elasticity of facial bones.1 It often includes entrapment of the extraocular muscle and orbital soft tissues, leading to ocular motility restriction, diplopia or, occasionally, severe oculocardiac reflex characterised by nausea, vomiting, bradycardia and syncope.2

A prompt surgery within 48 hours is always recommended in patients with symptomatic diplopia, severe ocular motility restriction, positive forced duction tests and entrapment of the orbital contents confirmed by CT scanning,3 especially the ‘white-eyed fracture’ raised by Jordan et al in 1998.4 It is generally considered that an urgent surgery within 48 hours can lead to better outcomes in children.5 6 In the presence of only soft-tissue entrapment (with mild motility restriction), a 2-week observation is recommended and surgery can be performed if symptomatic diplopia and/or motility restriction still exist after the oedema has mostly resolved.7

An urgent surgery usually demands highly of the triage of the emergency centre, arrangement of operation rooms, and corporation of anaesthetists and surgeons, especially in patients demanding surgeries within hours. However, sometimes this is hard to achieve. In China, especially, an uneven distribution or deficiency of oculoplastics surgeons in some areas, or a lack of knowledge in the management of orbital fracture usually makes urgent orbital surgery nearly impossible. Moreover, misdiagnosis or missed diagnosis of the fracture, or injuries of vital organs accompanied with trauma will also add to the difficulties for prompt surgery.

Most studies have focused on outcomes of prompt (within 48 hours)5 6 or early (within 2–4 days)6–8 surgery in trapdoor fracture patients with muscular entrapment, or early surgery within 2 weeks in patients with soft-tissue entrapment.9–11 In this study, we paid special attention to children with delayed (>4 days in muscular entrapment5–8 or >14 days in soft-tissue entrapment10 12) surgery for orbital trapdoor fracture with regard to clinical presentations, managements and outcomes. Both severe and mild motility restriction can occur in either of these two groups, but their management and outcomes could be quite different.

Materials and methods

This study followed the tenets of the Declaration of Helsinki. Approvals from Ethics Committee of Shanghai Ninth People’s Hospital were obtained to review the medical records for all paediatric patients presenting to the Department of Ophthalmology for orbital fractures between January 2008 and September 2016. Patients less than 18 years old, diagnosed with unilateral orbital trapdoor fracture, underwent delayed surgery (>4 days after injury in muscular entrapment or >14 days in soft-tissue entrapment) with follow-up for at least 1 year were included in the study, and those with incomplete medical records, previous surgery of orbital or facial fracture, visual impairment or anophthalmos were excluded. Ocular motility was evaluated on a numerical system of 0 to −4, with 0 representing no restriction and −4 representing no movement in the field of gaze.13 A severe motility restriction was defined as −3 or −4, and a mild one was defined as −1 or −2.

Altogether, 30 patients, including 18 boys and 12 girls, were enrolled in this study. Their medical records with regard to the causes of injury, causes of delay in surgery, clinical presentations, imaging data, implants and follow-up information were collected. These patients and their parents received informed consents.

The same team, led by XF, performed all surgeries. Implants included Medpor (Porex Surgical, Fairburn, Georgia, USA), Hydroxyapatite Sheet (YHJ Science and Trade, Beijing, China) and RapidSorb (Synthes, West Chester, Pennsylvania, USA).


The mean age was 7.63 years (SD 3.16 years, ranging from 3 to 14 years). According to the CT scan, they were classified into two groups. Extraocular muscle entrapment was found in 17 patients (56.7%) (group A) (figure 1A), and the other 13 patients only had a herniation of orbital soft tissues (group B) (figure 1B).

Figure 1

Coronal CT scans of paediatric patients with trapdoor fractures. (A) Right orbital floor. Yellow arrow indicates entrapment of orbital soft tissues with the inferior rectus muscle still inside the orbit.

The causes of orbital fractures are listed in table 1. Activities in daily life, including falls or crashes into other objects, accounted for over half of the patients in both groups as the most common causes of injury (52.9% and 53.8%, respectively). Fortunately, none of them suffered from assault or violence, which was common in adults.

Table 1

Distribution of patients by causes of injury

All patients in group A had missed the best surgical time and received delayed surgery. Their interval time to surgery ranged from 5 to 60 days with a mean of 16.7 days. The reasons for delay mainly fell into two categories: medical and personal reasons (table 2). Several medical factors played important roles in the delayed surgery in most of the patients (64.7%), leading to delayed admission to the oculoplastics clinics. Four patients (23.5%) were misdiagnosed with craniocerebral injury or under-recognised due to other medical problems elsewhere, and then found to have trapdoor fracture in further consultations. Seven patients (41.2%) were diagnosed with trapdoor fracture and transferred late to our department due to lack of oculoplastics surgeons or equipment. The other six (35.3%) were delayed for treatment because of personal reasons, including four (23.5%) with unstable clinical situations or anaesthetic concerns, which need further investigation, and two (11.8%) with concerns in the healthcare cost. The mean interval time of group B was 24.2 days after injury, ranging from 15 to 60 days, which was relatively longer than group A. Misdiagnosis with other diseases or missed diagnosis was the most frequent cause of delay in surgery (38.5%), followed by clinical instability of patients (30.8%).

Table 2

Reasons for delay in surgical treatment

Twenty-eight patients (93.3%) had orbital floor fractures, including 15 in group A and 13 in group B. Two patients were found to have combined orbital medial wall and floor fractures with inferior rectus muscle entrapment. All patients suffered from symptomatic diplopia within 30 degrees of primary gaze and motility restriction before surgery. Twelve were found to have severe motility restriction (table 3) and nine had periorbital soft-tissue swelling. None of them had nausea, vomiting or bradycardia. The absorbable implants RapidSorb were applied in 3 patients, Medpor in 19 patients and Hydroxyapatite Sheet in 8 patients according to surgeons’ preference, and no implant-related complications were found in the follow-up.

Table 3

Distribution of patients by ocular motility restriction and their outcomes

The mean follow-up time was 16.4 months. There were 20/30 (66.7%) patients who achieved full recovery of diplopia after surgery with an average of 7.4 months. In group A, 13/17 patients (76.5%) totally recovered from diplopia after surgery, compared with 53.8% (7/13) in group B. Table 4 concludes their recovery of diplopia after surgery in two groups. Significant difference was found in the recovery time between two groups with a p value 0.041.

Table 4

Patients with total recovery of diplopia after surgery

Altogether, 10/30 patients (33.3%) had persistent diplopia after surgery. In group A, 4/17 patients (23.5%) still had symptomatic diplopia in the last follow-up visit, and all of them had severe motility restriction before surgery. This percentage in group B, however, seemed to be even higher. There were 6/13 (46.2%) patients who presented with persistent diplopia with four in the primary gaze (within 30 degrees) and two in the peripheral gaze (beyond 30 degrees), and half of them were found with severe motility restriction. Among these eight patients with symptomatic diplopia, muscular surgeries were performed in seven of them 1 year after the orbital surgery with only one still left in observation.


Trapdoor fracture happens particularly in children and usually results in entrapment of the orbital contents. Prompt intervention has always been the main issue regarding the surgical timing, techniques or postoperative outcomes, especially in patients with severe motility restriction.3–6 In the actual clinical practice, however, a prompt surgery within several hours or days is hard to achieve. Some children have already been ‘delayed’ when they were referred to the department. So it is also important to know the clinical characteristics of these delayed patients, especially the impact of motility restriction level on their outcomes, so that we can manage them better.

In this study, we enrolled 30 children with orbital trapdoor fracture who had undergone delayed surgery and divided them into two groups according to their entrapped contents. There existed some differences in their reasons for delay between two groups. Late transfer from other departments or hospitals was the most frequent reason for delay in patients with muscular entrapment, while misdiagnosis/missed diagnosis was most common in patients with soft-tissue entrapment. These findings indicated that young patients might have various or complicated clinical presentations, which added to the difficulties of diagnosis.

However, these symptoms of delayed orbital trapdoor fracture were not unique enough to assist the diagnosis. Symptomatic diplopia and restricted ocular motility mainly in supraduction or infraduction were the most common symptoms, and rarely do patients presented with severe enophthalmos due to a slight decrease of the orbital contents. The triad symptoms of nausea/vomiting, bradycardia and syncope were clues for entrapment of orbital contents.14 The presence of nausea/vomiting was reported to occur in one-fourth of the children with entrapment,3 15 and had a positive predictive value of 83.3% for inferior rectus entrapment, which was an indication for prompt surgery.14 However, in a delayed condition, the proportion of these symptoms was much lower. Yang et al 16 reported only 1/7 (14.3%) patients had vagal symptoms (nausea/vomiting) with an interval of more than 96 hours, compared with 80% in patients operated on within 24 hours. In this study, such symptoms happened in none of our patients with delayed surgery. These subtle positive symptoms might give rise to diagnostic pitfalls in paediatric patients, thus leading to a delayed treatment or even a wait-and-see policy.4

CT scan plays an important role in the detection and definition of trapdoor fractures. However, it sometimes cannot clearly image the subtle herniation of soft tissues into fracture sites, which adds to the possibility of missed diagnosis.17 In the study of Parbhu et al, 18 they enrolled 24 paediatric patients, nearly half of whom were not operated on within 2 days, with orbital floor fracture and found that the concordance between radiographic and intraoperative findings of entrapment in the paediatric population was only 50%. Similar findings were also reported by other authors,4 17 19 which indicated that it is of great importance to perform a thorough ophthalmological assessment with the aids of radiologic results to clarify the diagnosis. In some cases, MRI can also be considered as an alternative to CT scan if entrapment is suspected but CT finding is negative.20 21

As for the surgical timing, it has been a consensus that prompt intervention will result in better postoperative outcomes in patients with muscular entrapment.5 6 8 15 Wei and Durairaj5  recommended a prompt surgery within 48 hours of diagnosis after a review of 25 articles about paediatric orbital trapdoor fracture with muscular entrapment. Chung and Langer2 reviewed the recent literature on paediatric orbital blowout fractures and recommended a surgery within 24 hours from the time of diagnosis. A long-term entrapment of extraocular muscle will cause insufficiency in the blood flow, and the resultant ischaemia will lead to fibrosis and muscular dysfunction, presenting as a high rate of persistent diplopia and restricted ocular mobility.4 Even after surgery to release the entrapment, the affected muscles still need a long time for recovery.16 Gerbino et al 6 included 15 paediatric patients with linear trapdoor fracture and muscular entrapment. After an average follow-up of 36 months, the incidence of persistent diplopia was 12.5% in patients who had undergone surgery within 24 hours, compared with 100.0% in delayed patients (more than 96 hours). In this study, the incidence of persistent diplopia was 23.5%, not as high as that in the study of Gerbino et al, but this rate was still much higher than that in the studies with urgent or early intervention. The average surgical timing was 144.0 days by Gerbino et al, compared with 17.3 days in this study, which might provide clues to the significance of urgent surgery in such patients.

In patients with soft-tissue entrapment, however, surgical timing remains a controversy. Orbital soft tissues usually refer to a complex network of fibrous septa demonstrated by Everhard-Halm e t al 23 including the sheath of the inferior rectus muscle, the fibro-fatty tissues and the periosteum of orbital floor. It will also result in restricted ocular mobility when any of its components is entrapped. An actual incarceration of the muscle belly is no more common than soft-tissue entrapment.5 8 15 In the study of Kim et al,24 only 5/18 (27.8%) cases were found with actual muscular entrapment. In this study of delayed condition, the rate of patients with soft-tissue entrapment is 43.3% (13/30). Several differences were found between the two groups, especially in therecovery time and rate of persistent diplopia after surgery. Therefore, the treatment principles for soft-tissue entrapment could also be different.

Patients with severe motility restriction were found to have a much higher incidence of persistent diplopia than mild ones. Ocular motility restriction level would be a very important factor in the determination of surgical timing in these patients with soft-tissue entrapment. If patients have severe motility restriction, they should be treated the same way as patients with muscular entrapment, even if there are only a few soft tissues entrapped in the fractured site. On the other hand, if patients presented with mild restriction, a prompt surgery within 48 hours might not be a necessity. Some studies also agreed that such patients could be managed expectantly without an increased risk of persistent diplopia.1 7 25 However, if the interval time is too long, the recovery of diplopia will still get worse. In this study, we found that patients with an interval time longer than 30 days suffered from a higher rate of persistent diplopia. In addition, that rate was even higher than that of group A, which was probably caused by a much longer interval time in group B. A delayed surgery may increase the complexity of the reconstruction and also increase the risk of complications, such as sinusitis, hypoglobus and diplopia.9 As a consequence, we assumed that in the absence of indications for prompt surgery (without severe motility restriction), patients with soft-tissue entrapment were still recommended to have surgery once diagnosed, even though some recovery of motility and diplopia might be possible in the long term.

The retrospective nature of this study should be viewed in light of several limitations. Despite the rarity of paediatric trapdoor fracture, the sample size in this study was relatively small. All of the patients in this study have received surgical treatment. The recovery of observational patients was not studied. So we recommend that future studies could focus on more paediatric patients, especially with soft-tissue entrapment, for more evidence to find out the appropriate surgical timing.

In conclusion, long recovery time and a high percentage of persistent diplopia postoperatively are the main problems of delayed trapdoor fracture children. A prompt surgery within 48 hours after diagnosis is strongly recommended in patients with muscular entrapment even if an urgent treatment is hard to achieve. So are patients with soft-tissue entrapment and significant motility restriction. In the other patients without such indications, even though some recovery might be possible in the long term, a prompt surgery after diagnosis is still preferable regardless of the entrapped contents.



  • Contributors Study concept and design: XF, ML. Analysis or interpretation of data: all authors. Drafting of the manuscript: YS. Critical revision of the manuscript for important intellectual content: all authors. Statistical analysis: YS, QS. Obtained funding: YS, XB, XF. Administrative, technical or material support: all authors. Study supervision: XF, ML.

  • Funding This work was supported by the Science and Technology Commission of Shanghai (17DZ2260100), Shanghai Municipal Education Commission–Gaofeng Clinical Medicine Grant Support (20161419) and Shanghai Jiao Tong University Biomedical Engineering Research Fund (YG2016QN03).

  • Disclaimer All authors had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. 

  • Competing interests None declared.

  • Patient consent Guardian consent obtained.

  • Ethics approval Approvals from Ethics Committee of Shanghai Ninth People’s Hospital were obtained.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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