Patient-Specific Implants in Oculofacial Plastic Surgery

Advances in Midface Reconstruction

The complexity of the midface structure and its importance to a multitude of functions present the reconstructive surgeon with unique challenges. The midface is an area that is crucial both functionally and esthetically. Midface reconstructions can make profound differences in form and function. This review focuses on complex midface and maxillary reconstructions requiring free tissue transfer.

A method for accuracy of placement analysis on radiolucent polyether-ether-keton facial implants: A case series

Facial asymmetry is defined as a bilateral difference between facial components. Correction, often desired by the patient, can be performed with the aim of bone born patient-specific solid implants designed using 3D CAD software. This treatment is embedded in the daily practice of today's healthcare. However, an analysis of the implant's accuracy of placement has not been reported. This case series describes the accuracy analysis of bone born aesthetic facial implants manufactured out of polyether-ether-ketone (PEEK). The accuracy analysis was based on postoperative (cone beam) computed tomography ((CB)CT) data and preoperative 3D planning. The analysis showed a median entry point error of 0.7 mm (min: 0.1, max: 3.3, interquartile range: 0.78). The median maximal orientation error was 5.5° (min: 0.1, max: 36.8, interquartile range: 7.13). Both parameters showed an excellent intraobserver and interobserver agreement with an ICC above 0.84. The described cases show that the analysis method is an objective approach for determining the accuracy of PSI placement and indicates that these implants can be placed accurately on the osseous face.

Patient Specific Implants for Orbital Reconstruction in the Treatment of Silent Sinus Syndrome: Two Case Reports

Silent sinus syndrome is a rare disorder characterized by ipsilateral enophthalmos and hypoglobus following a collapse of the orbital floor, in the presence of asymptomatic long-term maxillary sinusitis. It results in enophthalmos, hypoglobus and deepening of the superior palpebral sulcus. A standardized treatment protocol for this infrequent syndrome has not yet been established. The management includes restoration of maxillary sinus ventilation with functional endoscopic sinus surgery and orbital reconstruction, either concurrently or separately. In this paper, the authors presented two patients successfully treated with patient-specific implants, and intraoperative navigation. These cases highlight the benefit of computer-assisted planning and titanium patient-specific implants in the management of silent sinus syndrome. To the best of our knowledge, this is the first report that described the use of PSI with titanium spacers performed with the aid of intraoperative navigation for SSS treatment. Advantages, drawbacks of this technique and treatment alternatives currently available in the literature were also discussed.

Patient-Specific Orbital Implants Vs. Pre-Formed Implants for Internal Orbital Reconstruction

PURPOSE

To compare the outcome of orbital blowout fracture repair by means of pre-formed porous-polyethylene titanium implants (PFI) vs patient-specific porous-polyethylene implants (PSI).

METHODS

Retrospective cohort study. Baseline characteristics, ophthalmic examination results, ocular motility, fracture type, the timing of surgery, implant type, and final relative enophthalmos of all patients operated on for blow-out fractures in a single center were collected and analyzed.

RESULTS

Twenty-seven patients (mean age 39 years, 9 females) were enrolled. Sixteen underwent fracture repair with PFI and 11 with PSI at 11 months (median) post-trauma. Mean follow-up duration was 1.1 years. Both groups showed significant postoperative improvement in primary or vertical gaze diplopia (P = .03, χ²). Relative enophthalmos improved from -3.2 preoperative PFI to -1.7 mm postoperative PFI, and from -3.0 mm preoperative PSI to -1.1 mm postoperative PSI (P= .1). PSI patients had non-significantly less postoperative enophthalmos and globe asymmetry than PFI patients. The outcome was not influenced by previous surgery, age, sex, number of orbital walls involved in the initial trauma, or medial wall involvement (linear regression). Both groups sustained complications unrelated to implant choice.

CONCLUSION

Both PSI and PFI yielded good outcomes in this study. PSI may be a good alternative to PFI in primary or secondary orbital blowout fracture repair with less enophthalmos and globe asymmetry, in spite of the possible disadvantages of production time, a relatively larger design, and challenging insertion. Since it is a mirror image of the uninjured orbit, it may be beneficial in extensive fractures.

3D Printing in Eye Care

Three-dimensional printing enables precise modeling of anatomical structures and has been employed in a broad range of applications across medicine. Its earliest use in eye care included orbital models for training and surgical planning, which have subsequently enabled the design of custom-fit prostheses in oculoplastic surgery. It has evolved to include the production of surgical instruments, diagnostic tools, spectacles, and devices for delivery of drug and radiation therapy. During the COVID-19 pandemic, increased demand for personal protective equipment and supply chain shortages inspired many institutions to 3D-print their own eye protection. Cataract surgery, the most common procedure performed worldwide, may someday make use of custom-printed intraocular lenses. Perhaps its most alluring potential resides in the possibility of printing tissues at a cellular level to address unmet needs in the world of corneal and retinal diseases. Early models toward this end have shown promise for engineering tissues which, while not quite ready for transplantation, can serve as a useful model for in vitro disease and therapeutic research. As more institutions incorporate in-house or outsourced 3D printing for research models and clinical care, ethical and regulatory concerns will become a greater consideration. This report highlights the uses of 3D printing in eye care by subspecialty and clinical modality, with an aim to provide a useful entry point for anyone seeking to engage with the technology in their area of interest.

Patient specific implants in orbital reconstruction: A pilot study

Purpose

Successful repair of the orbital skeleton restores function and cosmesis by normalizing globe position and allowing full motility of the extraocular muscles. Routine repairs are successful with standard implants. However, defects that are irregular or cause volume deficiency can be challenging to repair. The development of patient specific implants (PSI) offers an additional tool in complex cases. Herein, we report our experience using PSI for orbital reconstruction.

Methods

An IRB-approved review was conducted of consecutive patients who received PSI from 8/2016–9/2018. Demographic and examination findings were recorded. PSI was designed using high-density porous polyethylene or polyetheretherketone (PEEK) and implanted for repair. The postoperative course was reviewed for outcomes and complications.

Results

Eight patients were identified. Two had silent sinus syndrome, 3 were complex facial fracture revisions, and 3 were post-oncologic reconstruction. Seven received porous polyethylene implants, and 1 had a PEEK implant. Mean follow up time was 10.2 months (3.3–28.3). All had an improved functional and aesthetic result. Diplopia and enophthalmos completely resolved in 60% of fracture and silent sinus patients. All fracture and silent sinus patients were orthotropic without diplopia in primary gaze at last follow up. Tumor patients had improvement in symmetry and functionality. There were no complications.

Conclusion and importance

Complex orbital skeleton derangements can be difficult to repair and standard implants may incompletely resolve the anatomic problem. In challenging cases, PSI may better achieve an aesthetically and anatomically successful outcome and improve functionality.