Evaluation of the Retro-Orbital Fatty Tissue Volume in Delayed Orbital Blow-Out Fractures

Prospective Evaluation of Intraorbital Soft Tissue Atrophy after Posttraumatic Bone Reconstruction: A Risk Factor for Enophthalmos

Orbital fractures are a common finding in facial trauma, and serious complications may arise when orbital reconstruction is not performed properly. The virtual planning can be used to print stereolithographic models or to manufacture patient-specific titanium orbital implants (PSIs) through the process of selective laser melting. This method is currently considered the most accurate technique for orbital reconstruction. Even with the most accurate techniques of bone reconstruction, there are still situations where enophthalmos is present postoperatively, and it may be produced by intraorbital soft tissue atrophy. The aim of this paper was to evaluate the orbital soft tissue after posttraumatic reconstruction of the orbital walls’ fractures. Ten patients diagnosed and treated for unilateral orbital fractures were included in this prospective study. A postoperative CT scan of the head region with thin slices (0.6 mm) and soft and bone tissue windows was performed after at least 6 months. After data processing, the STL files were exported, and the bony volume, intraorbital fat tissue volume, and the muscular tissue volume were measured. The volumes of the reconstructed orbit tissues were compared with the volumes of the healthy orbit tissues for each patient. Our findings conclude that a higher or a lower grade of fat and muscular tissue loss is present in all cases of reconstructed orbital fractures. This can stand as a guide for primary or secondary soft tissue augmentation in orbital reconstruction.

Primary reconstruction of extensive orbital fractures using two-piece patient-specific implants: the Helsinki protocol

PURPOSE

We present our experience of titanium-milled two-piece patient-specific implants (PSIs) for primary reconstructions of extensive orbital floor and medial wall fractures (EOFMFs) and evaluate their postoperative functional and aesthetic outcomes in relation to commercially available implants.

METHODS

We included all patients with primary reconstructions (< 22 days from injury) of EOFMFs treated in our department between January 2011 and October 2020. Extensive orbital floor and medial wall fracture was defined as involvement of orbital floor, medial wall and maxilloethmoidal junction; a fracture defect 5 mm or more; defect size more than a third of both inferior and medial walls; and Jaquiéry classification III or more. Patient characteristics, details of fracture defects and surgeries, postoperative outcomes and implant positions were retrospectively evaluated and compared between study groups.

RESULTS

Nineteen patients were included: 5 with two-piece PSIs and 14 with commercial implants. Implant position was good in 4/5 patients with two-piece PSIs and 2/14 with commercial implants. Revision surgery, globe malposition (GMP) > 2 mm, significant diplopia and poor implant position were more frequent in patients with commercial implants than two-piece PSIs. None of the patients with a good overall implant position had any significant postoperative symptoms.

CONCLUSION

Extensive orbital fracture reconstructions are somewhat rare, and surgical treatment is associated with a high rate of complications and postoperative symptoms. Titanium-milled two-piece PSIs are well suited for primary reconstructions of EOFMFs, as they lead to more precise reconstructions and fewer postoperative symptoms than commercially available implants.

Orbital Volume and Axial Length Development in Individuals Ages 12 to 60 Years With Congenital Microphthalmia: A Retrospective Cohort Study

OBJECTIVE

To analyze the stimulating effect of axial length development on orbital volume development in patients (ages 12-60 years) with congenital microphthalmia.

METHODS

This retrospective cohort study included 43 patients (86 eyes) with congenital microphthalmia. Three-dimensional images of the orbit were generated from past computed tomography scans, and digital orbital volume and axial length measurements were taken. The patients were divided into four age groups for analyses. Paired t tests and one-way analysis of variance tests were used to compare orbital volume and axial length between the affected and unaffected eyes. Pearson correlation analyses and scatter plots were used to investigate the correlations between age, orbital volume, and axial length in the affected and unaffected eyes. Linear regression analysis was used to determine the association between orbital volume and axial length.

RESULTS

The mean orbital volume in the affected and unaffected eyes was 17.08 ± 2.88 and 20.80 ± 2.55 cm3, respectively. The mean axis length in the affected and the unaffected groups was 12.73 ± 3.54 and 23.84 ± 1.43 mm, respectively. Significant differences were observed among orbital (t = 13.538, P < 0.001) volume and axial length (t = 21.339, P < 0.001) in the affected and the unaffected groups. There were no significant differences in affected orbital volume (F = 0.527, P > 0.05), unaffected orbital volume (F = 1.628, P > 0.05), affected axial length (F = 0.946, P > 0.05), and unaffected axial length (F = 2.217, P > 0.05) among the four age groups. According to the Pearson correlations, there were no significant correlations between age and affected volume, unaffected volume, affected axis, and unaffected axis (r = 0.095, 0.097, 0.084, and 0.022, respectively; all P > 0.05). Orbital volume was moderately correlated with axial length in the affected and unaffected groups (r = 0.470 and 0.410, respectively; both P < 0.01). Linear regression analysis revealed that a 1 mm change in axis length was associated with a 0.38 cm3 and 0.73 cm3 change in orbital volume in the affected and unaffected groups, respectively.

CONCLUSIONS

In individuals ages 12 to 60 years old with congenital microphthalmia, the effect of axis length on the orbital volume growth of the affected eye is only half that of the unaffected eye. The eyeball, orbital tissue, and craniofacial development all play an important role in the growth of orbital volume.

An accurate interactive segmentation and volume calculation of orbital soft tissue for orbital reconstruction after enucleation

Background

Accurate measurement and reconstruction of orbital soft tissue is important to diagnosis and treatment of orbital diseases. This study applied an interactive graph cut method to orbital soft tissue precise segmentation and calculation in computerized tomography (CT) images, and to estimate its application in orbital reconstruction.

Methods

The interactive graph cut method was introduced to segment extraocular muscle and intraorbital fat in CT images. Intra- and inter-observer variability of tissue volume measured by graph cut segmentation was validated. Accuracy and reliability of the method was accessed by comparing with manual delineation and commercial medical image software. Intraorbital structure of 10 patients after enucleation surgery was reconstructed based on graph cut segmentation and soft tissue volume were compared within two different surgical techniques.

Results

Both muscle and fat tissue segmentation results of graph cut method showed good consistency with ground truth in phantom data. There were no significant differences in muscle calculations between observers or segmental methods (p > 0.05). Graph cut results of fat tissue had coincidental variable trend with ground truth which could identify 0.1cm³ variation. The mean performance time of graph cut segmentation was significantly shorter than manual delineation and commercial software (p < 0.001). Jaccard similarity and Dice coefficient of graph cut method were 0.767 ± 0.045 and 0.836 ± 0.032 for human normal extraocular muscle segmentation. The measurements of fat tissue were significantly better in graph cut than those in commercial software (p < 0.05). Orbital soft tissue volume was decreased in post-enucleation orbit than that in normal orbit (p < 0.05).

Conclusion

The graph cut method was validated to have good accuracy, reliability and efficiency in orbit soft tissue segmentation. It could discern minor volume changes of soft tissue. The interactive segmenting technique would be a valuable tool for dynamic analysis and prediction of therapeutic effect and orbital reconstruction.

Is there more to the clinical outcome in posttraumatic reconstruction of the inferior and medial orbital walls than accuracy of implant placement and implant surface contouring? A prospective multicenter study to identify predictors of clinical outcome

PURPOSE

Reconstruction of orbital wall fractures is demanding and has improved dramatically with the implementation of new technologies. True-to-original accuracy of reconstruction has been deemed essential for good clinical outcome, and reasons for unfavorable clinical outcome have been researched extensively. However, no detailed analysis on the influence of plate position and surface contour on clinical outcome has yet been published.

MATERIALS AND METHODS

Data from a previous study were used for an ad-hoc analysis to identify predictors for unfavorable outcome, defined as diplopia or differences in globe height and/or globe projection of >2 mm. Presumed predictors were implant surface contour, aberrant implant dimension or position, accuracy of reconstructed orbital volume, and anatomical fracture topography according to the current AO classification.

RESULTS

Neither in univariable nor in multivariable regression models were unfavorable clinical outcomes associated with any of the presumed radiological predictors, and no association of the type of implant, i.e., standard preformed, CAD-based individualized and non-CAD-based individualized with its surface contour could be shown.

CONCLUSION

These data suggest that the influence of accurate mechanical reconstruction on clinical outcomes may be less predictable than previously believed, while the role of soft-tissue-related factors may have been underestimated.