An orbital floor implant is a medical device used to repair the thin bone beneath the eyeball, known as the orbital floor. Its primary purpose is to restore the normal structure and volume of the eye socket following a fracture. This intervention helps to reposition the eyeball and support the surrounding soft tissues. The implant provides a stable platform for the eye, aiming to improve both function and appearance after an injury.
Understanding Orbital Floor Fractures
The orbit, or eye socket, is a bony structure that encases and protects the eyeball. Its floor is particularly thin and delicate, making it susceptible to injury. A “blowout fracture” commonly occurs when a blunt force impacts the eye, causing a sudden increase in pressure within the orbit. This leads to the fracture of the orbital floor, pushing the eyeball backward and allowing orbital contents to drop into the maxillary sinus below.
Symptoms indicating a need for surgical repair often include enophthalmos, a sunken appearance of the eye caused by orbital fat herniation. Double vision, known as diplopia, frequently occurs if eye muscles, particularly the inferior rectus, become trapped within the fracture site, restricting eye movement. Swelling and bruising around the eye are also common indicators of this injury.
Types of Orbital Floor Implants
Non-Absorbable (Permanent) Implants
Permanent implants are designed to remain in the body indefinitely, providing long-term structural support. Titanium mesh is a common choice due to its strength and biocompatibility. This material is rigid, maintains its shape well, and is visible on imaging scans, allowing for easy post-operative assessment. While highly stable, titanium mesh does not integrate with surrounding tissues.
Porous polyethylene (Medpor) is another frequently used non-absorbable material. Its porous structure allows for tissue ingrowth, which helps to anchor the implant in place and reduce the risk of migration. This material is also stable and generally well-tolerated by the body. However, it can be more challenging to remove if revision surgery becomes necessary due to the tissue integration.
Absorbable (Resorbable) Implants
Absorbable implants are temporary solutions that dissolve gradually over time, typically several months to a year, after providing initial structural support. Materials like polydioxanone (PDS) plates are used. These implants are chosen when only temporary support is needed for bone healing, or in cases where the defect is smaller and less severe.
The main advantage of absorbable implants is they eventually disappear, leaving no foreign material in the body long-term. A disadvantage is their limited strength and duration of support compared to permanent options. They may not be suitable for larger fractures requiring sustained structural integrity.
Autologous Grafts (Bone Grafts)
Autologous grafts involve using the patient’s own bone tissue to repair the orbital floor defect. Common donor sites include the skull (calvarial bone), a rib, or the hip (iliac crest). This approach minimizes the risk of rejection or adverse reactions because the material is from the patient’s own body.
Bone grafts offer natural integration with surrounding bone, potentially leading to a more complete anatomical restoration. However, using autologous grafts requires an additional surgical site for harvesting the bone, which introduces a separate incision and potential for donor site pain or complications. The availability and shape of suitable bone can also be a limiting factor.
The Surgical Repair Procedure
Orbital floor repair surgery is performed under general anesthesia. The specific surgical approach is chosen based on the fracture’s location and extent, aiming to minimize visible scarring. A common method is the transconjunctival approach, where the incision is made inside the lower eyelid, leaving no external scar. The subciliary approach involves an incision just below the eyelashes, which typically heals very well and is barely noticeable.
The surgeon gently elevates the orbital contents, including the eyeball and surrounding soft tissues, to expose the fractured orbital floor. Any bone fragments or herniated tissue are carefully cleared from the fracture site. The chosen implant is then precisely placed to cover the defect, restoring the orbital floor’s integrity and supporting the eye.
Post-Operative Recovery and Risks
Following orbital floor repair surgery, patients can expect some swelling and bruising around the eye and cheek, which typically subsides over several weeks. Pain is generally managed with prescribed medications, and cool compresses may be applied to help reduce swelling. Visual blurring or double vision may be present initially due to swelling but often resolves as recovery progresses.
Patients are advised to avoid activities that increase pressure in the head, such as blowing their nose forcefully, for several weeks to prevent air from entering the orbit. Heavy lifting, strenuous exercise, and contact sports are also restricted for approximately six to eight weeks to protect the healing area. Regular follow-up appointments are scheduled to monitor healing and assess the eye’s position and movement.
Complications include infection, which may require antibiotic treatment or, in some cases, implant removal. The implant could also shift or become displaced, potentially necessitating revision surgery. Persistent double vision or enophthalmos may occur if the muscle entrapment is not fully resolved or if the orbital volume is not adequately restored. Nerve damage, though uncommon, can lead to temporary or permanent numbness in the cheek, upper teeth, or upper lip due to the infraorbital nerve’s proximity.
Long-Term Outcomes with an Implant
Permanent orbital floor implants, such as those made from titanium or porous polyethylene, are designed to remain in place for the rest of a patient’s life. These implants rarely require removal unless complications like infection or significant displacement arise. They are generally well-integrated and do not degrade over time. The success rate for orbital floor repair surgery in restoring normal eye function and appearance is generally high, with many patients experiencing significant improvement in symptoms like double vision and enophthalmos after full recovery.