The nasal bone is a prominent feature of the central face and is the most common fracture site in facial bone. Nasal bone fractures account for 40% of facial bone fractures and is the third most common of all skeletal fractures [1]. If reduction is not performed properly, contracture and fibrosis of soft tissue can result in nasal deformity and functional problems, such as septal deviation, nasal obstruction, and temporary hyposmia [2]. Therefore, exact diagnosis and treatment is important to obtain good outcome. Because nasal bone fracture is considered a minor injury, accurate diagnosis and precise reduction tend to be overlooked, and often results in multiple forms of nasal deformities even after the operation [3]. However, we found that nasal deformity from the immediate postoperative period tended to improve with time.

This study analyzes acute bone remodeling or realignment of nasal bone after closed reduction on computed tomography (CT) images taken preoperatively, immediately after the operation, and at one month after the operation. The degree of nasal bone repositioning was analyzed according to fracture types.

Exact diagnosis of nasal bone fracture is difficult when using only simple X-ray imaging [5]. This is because the normal anatomy of the nasal bone is difficult to distinguish in 2-dimensional projections and because soft tissue edema may obscure the fracture line [6]. Because any portion of the X-ray consist of penetration data from multiple layers and thicknesses of tissue, determining the extent and exact location of a fracture is difficult even if it was identified in the first place in comparison, CT images enable a more accurate study of nasal bone fractures, determine the degree and direction of fracture, and the exact position of fracture. It facilitates reduction of the fracture and can also provide information regarding the damages to the surrounding area, including soft tissue and other facial bones [7].

Many studies have reported on the effectiveness of CT examination for diagnosis and postoperative evaluation of nasal bone fracture [8,9,10]. On the other hand, CT scanning is associated with higher radiation dose and its use is to be restrained as much as possible. Therefore, the repeat CT examinations were performed at the request of patients who expressed a desire to personally view the results of operation. Among younger patients who were still going facial bone growth, the parents worried about the possibility of abnormal nasal bone growth or nasal deformity after fracture reduction. In these situations, repeat CT scans offer several advantages including an increased confidence in postoperative outcomes for the patients and parents.

The outcomes was excellent for 10 patients (20%), good for 31 patients (62%), fair for 8 patients (16%), and poor for a singles patient (2%) on immediate postoperative CT studies. At one month after reduction, these outcomes had improved to excellent for 37 patients (74%), good for 12 patients (24%), and fair for one patient (2%). Of all patients, 30 patients (60%) showed immediate postoperative improvement of reduction. While 20 patients (40%) showed no change, none of the closed reduction was associated with any worsening parameters.

Properly reduced nasal bone fragments are placed under self-supporting force and are capable of maintaining the pyramidal configuration. Because nasal bone is membranous, the state of bone stump has an important effect on bone repair, more so when comparing reduction of long bones. The surrounding connective tissue and both layers of periosteum are important for progressive remodeling of reduced nasal bone. Therefore, both recovery of continuity by minimizing bony gap in the fracture segment and prevention of damage to the periosteum are important to obtaining good postoperative outcomes [11,12].

Patient (and parental) evaluation of postoperative outcomes can often be misleading because the external shape of the nose is under the influence of swelling and bone remodeling. Therefore, accurate diagnosis before the operation, precise reduction, careful management preventing of damage to periosteum and mucosa of the nasal bone, and thorough postoperative care are important in obtaining desired outcomes.

In this study, postoperative outcomes continued to improve during the first month after operation: in the FI group, seven patients of 14 patients; in the FII group, three patients of four patients; in the LI group, eight patients of 13 patients; in the LII group, four patients of 14 patients; in the C group, three patients of five patients. As septal fracture or preexisting septal deviation is often accompanied by nasal bone fracture, it is likely to develop complication such as postoperative nasal deformity with a negative effect on facial aesthetics [13]. We attempted to identify the relationship, if it exists, between nasal bone remodeling and the presence of septal deviation. However, no meaningful relationships were identified for nasal bone remodeling with either preoperative septal fracture or preexisting septal deviation. In addition, there were no statistically significant relationship between nasal bone remodeling and the presence of septal deviation at one month after operation.

In conclusion, it seems that reduced nasal segments tend to undergo progressive remodeling and that postoperative outcomes continued to improve over the first month. However, the current study has some limitations. The CT outcomes were not correlated with clinical examination parameters including the overall shape of external nose. Before the result of this study can be generalized, further studies are needed to overcome the small study size due to limited application of CT examination from concerns regarding ionizing radiation.