Reconstruction of an orbital fracture in a mare using a 3D-printed patient-specific implant.

Overview

• This study reports the successful surgical repair of a complex orbital fracture in a horse using a custom 3D-printed implant designed specifically for the patient’s unique anatomy.

Background and Purpose

• Orbital fractures in horses, especially those involving communication with sinuses, pose a challenge for surgical repair due to complicated anatomy and the need to restore both function and cosmetic appearance.
• The researchers aimed to describe the surgical technique and outcomes using a three-dimensional (3D)-printed patient-specific implant (PSI) to reconstruct the orbital wall and seal the communication with the sinus.

Subject and Clinical Presentation

• The patient was a 25-year-old Haflinger mare weighing approximately 370 kg.
• She presented with severe chemosis (swelling of the conjunctiva) and emphysema (air trapped under the skin) of the left upper and lower eyelids that had persisted for two weeks.
• The underlying cause was identified as a fracture of the ventral floor and inner wall of the left orbit, which communicated with the caudal maxillary sinus.

Diagnostic Approach and Implant Design

• Computed tomography (CT) scans were performed to capture detailed 3D images of the fractured orbital structures.
• CT data from the unaffected side’s orbit were used to digitally replicate the inner surface anatomy of the orbit in a computer-aided design program.
• The resulting implant model was converted into an STL (stereolithography) file format suitable for 3D printing.
• A patient-specific implant (PSI) was fabricated using a 3D printer with polylactic acid (PLA) filament, a biocompatible plastic material.

Surgical Procedure

• Surgical access to the orbit was gained via a concho-frontal sinus flap, a technique that provides visibility and access to the orbit and associated sinuses.
• Additionally, sinoscopy (endoscopic examination of the sinus) was used to assist in visualization and assessment.
• The PSI was lined with porcine small intestinal submucosa, a biological material commonly used to support tissue healing and encourage integration.
• The implant was secured to the inner orbital wall using two 3.0 mm titanium locking screws, providing rigid fixation.
• Further stabilization was achieved with synthetic, non-absorbable transosseous fiber loops passing through bone tunnels to firmly anchor the implant.

Postoperative Outcomes and Complications

• The emphysema resolved following the surgery, indicating effective sealing between the orbit and the sinus.
• Ocular function was restored without impairment from the implant, suggesting successful anatomical and functional reconstruction.
• A subcutaneous infection occurred near the site of transosseous suture fixation on the maxillary bone, possibly due to the fixation method or materials used.
• The infection was managed non-surgically with conservative treatment (e.g., antibiotics, wound care) and resolved without further complication.

Follow-up and Long-Term Outcome

• Follow-up CT scans performed 11 weeks after surgery demonstrated stable positioning of the implant and healing of the fracture.
• The horse’s owner reported favorable cosmetic and functional outcomes 18 months postoperatively.
• The only noticeable residual problem was minimal ptosis (drooping) of the left upper eyelid, which did not affect overall function significantly.

Conclusions and Clinical Implications

• This case demonstrates that 3D-printed, patient-specific implants can successfully reconstruct complex orbital wall fractures in horses, including those with sinus communication.
• The application of PSI allowed for precise anatomical restoration and durable fixation, enabling symptom resolution and functional recovery.
• Patient-specific implants offer a novel, tailored surgical option in equine orbital trauma, potentially improving outcomes in difficult cases.
• Future considerations include monitoring for infection at fixation sites and evaluating material choices to minimize complications.