Nasal orbital sieve fractures are different from nasal bone fractures, which are fractures that occur jointly in the nasal, septal sinus, and internal orbital regions. Fractures of the nasal orbital sieve region can occur alone or with other fractures of the craniofacial region. Because of the complex anatomy of the naso-orbital sieve region and its proximity to important structures such as the orbit and skull, the treatment of its trauma is a clinical challenge.
Surgical Anatomy
The nasal orbital sieve region, also known as the nasal orbital sieve complex, is located in the central superior part of the midface, and its bony structure consists of nasal bone, lacrimal bone, sieve bone, maxillary bone, and frontal bone, and each bone interlocks with each other to form a matchbox-like structure, which is relatively fragile. When external force acts on the stent in the anterior part of the sieve of the nasal orbit, the stent collapses and shifts backward and outward, resulting in widening of the medial canthal distance and saddle nose deformity, which may also be complicated by frontal sinus fracture, anterior cranial recess fracture, and eye injury.
The septal sinus is separated by very thin bone fragments into a honeycomb-like structure, which is brittle and fragile. The blood supply to the septal sinus is supplied by the anterior and posterior septal arteries, and trauma can result in vascular tearing and intraorbital hemorrhage. The frontal sinus is located behind the arch of the eyebrow between the inner and outer layers of the frontal bone and above the septal sinus, and opens in the middle nasal canal through the nasofrontal canal. Fractures in the septal area of the nasal orbit can involve the nasofrontal canal and lead to poor drainage of the frontal sinus and inflammation.
The medial canthal ligament pulls the upper and lower eyelids, facilitating the collection and excretion of tears and supporting the attachment stability of the orbicularis oculi and the opening and closing of the eyes. Injury to the medial canthal ligament can result in distal medial canthus deformity, rounded medial canthus, and overflow of tears. The lacrimal duct is another important soft tissue structure in the nasal orbital sieve area. Fractures in the nasal orbital sieve area can compress or sever the lacrimal duct, resulting in tear overflow and lacrimal sac infection after injury.
Classification of fractures
Markowitz (1991) classified nasorbital sieve fractures into three types.
Type I: Whole fracture of the central bone segment without displacement or mild displacement, with no detachment of the medial canthal ligament. Treatment is based on resetting the fracture.
Type II: partial comminution and displacement of the central bone segment, but the medial canthal ligament is not detached from the bone fragment, and the fracture can be fixed with a splint after repositioning.
Type III: Comminuted fracture of the central bone segment with detachment of the medial canthal ligament. The central bone segment needs to be reconstructed with bone graft and the medial canthal ligament needs to be reattached.
Cause of fracture
Most nasal orbital sieve fractures are caused by motor vehicle traffic accidents.
Fracture diagnosis
In addition to local injuries, attention should be paid to injuries to other parts of the body, with emphasis on cranial and ocular injuries. If cranial and ocular injuries are suspected, prompt consultation with neurosurgeons and ophthalmologists should be sought.
1, medical history
Ask the patient or family to understand the specific injury, whether there is a history of post-injury coma, etc.
2.Clinical manifestations
The acute phase of fracture shows nasal bleeding, dorsal and periorbital petechiae, periorbital and subconjunctival hemorrhage. After the swelling subsides, deformities such as widening of the canthal distance, rounding of the inner canthus, collapse of the nasal bridge, and upturning of the nasal tip may appear. When accompanied by skull base fracture, cranial pneumatization and cerebrospinal fluid leakage may occur. Some patients present with varying degrees of olfactory loss, ocular entropion, ocular motility disorders and diplopia.
The canthal ligament can be examined by the “eyelid pull test”. If the canthal ligament loses its bowstring-like tautness, the canthal ligament is loose.
3.Imaging
Imaging examinations can help clarify the diagnosis of fracture and serve as evidence for forensic medicine, and can also guide the development of surgical plans.
(1) Plain radiographs such as Fahrenheit, Koch, and nasal bone front and side are used to observe the fracture of the nasal orbital sieve area, which can provide some information but are not subtle and comprehensive.
(2) Two-dimensional CT images such as CT axial and coronal images combined with three-dimensional reconstructed images can clarify the diagnosis of nasorbital septal fracture and observe the details of fracture in the orbit, septal sinus and frontal sinus.
Fracture treatment
When the cranial injury is controlled, surgery should be performed as early as possible. The key elements of early surgery include: repositioning and fixing the central bone segment and the medial canthal ligament; reconstructing the orbital wall to restore the orbital volume; and reconstructing the external nasal scaffold with bone graft to restore the nasal shape.
(1) Resetting and fixation of the central bone segment The reconstruction of the central bone segment is completed by resetting the fracture fragment, repairing the bone defect and sturdy internal fixation.
(2) Suspension of the medial canthal ligament is done by suspending the medial canthal ligament over the posterior aspect of the posterior lacrimal crest. If both ligaments need to be suspended, they can be fixed with a pair of ligatures.
(3) External nasal bony scaffold reconstruction Most nasal orbital sieve fractures require bone graft reconstruction of the nasal bony scaffold. stage I bone graft reconstruction is effective in reducing deformities secondary to soft tissue scarring.
(4) The management of frontal sinus fracture pays particular attention to the injury of the nasofrontal canal, and the procedures of simple fracture repositioning and fixation, frontal sinus filling, and frontal sinus cranialization are chosen according to the specific situation of frontal sinus fracture.
Postoperative precautions
Postoperative antibiotics are applied for about 3 days according to the injury and surgery. The antibiotics can be penicillin, cephalosporin antibiotics or clindamycin, etc. Postoperative observation of visual acuity and the improvement of intraocular sunkenness and diplopia. Postoperative CT examination to clarify the fracture reset. Postoperative patients follow the doctor’s advice for review recommendations and imaging examinations.