Orbital Reconstruction Basics
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Direct answer
After an orbital fracture, the surgeon's scoreboard has two entries — orbital volume and ocular motility. Volume: herniated fat and muscle into the maxillary sinus enlarge the orbit and pull the globe back, producing enophthalmos (a difference of 2 mm or more from the normal side matters). Motility: entrapment of the inferior rectus or connective tissue septa restricts upgaze and causes diplopia, confirmed intraoperatively by a positive forced duction test. Reconstruction restores the floor (and medial wall if involved) with autogenous bone, titanium mesh or porous polyethylene, approached through a subciliary, subtarsal or transconjunctival incision, ideally within about two weeks before fat fibroses in the sinus.
What you must remember
- Surgical anatomy: the orbital floor is the shortest wall; the medial wall (lamina papyracea) is the thinnest; the lateral wall is the strongest — fracture patterns follow this hierarchy.
- Indications for reconstruction: floor defect involving roughly half the floor or extending posterior to the equator of the globe, enophthalmos of 2 mm or more, diplopia that persists beyond observation with a positive forced duction test, and large herniation on computed tomography.
- Approaches: subciliary (excellent access, ectropion risk), subtarsal/midlid (balances scar and access), transconjunctival with or without lateral canthotomy (no skin scar, the modern default), and transcaruncular extension for the medial wall.
- Implant materials: autogenous bone (iliac crest, rib, calvarium, maxillary wall), titanium mesh, porous polyethylene (Medpor) which allows tissue ingrowth, and resorbable sheets for small defects.
- The volume arithmetic: roughly 1 cubic centimetre of orbital volume increase produces about 0.8-1 mm of enophthalmos — the reason small residual defects still cause measurable globe position change.
- Timing: early repair, commonly within the first two weeks, before herniated fat fibroses and enophthalmos becomes fixed; pure paediatric trap fractures with marked restriction are emergencies.
- Feared complication: retrobulbar haemorrhage — pain, tense proptosis, vision loss — treated urgently by wound release and lateral canthotomy with cantholysis, the one true orbital emergency after surgery.
Working through a blowout fracture case
A 30-year-old punched under the eye presents with periorbital ecchymosis, diplopia on upgaze and slight enophthalmos. Computed tomography (coronal and axial) shows a 60 percent floor defect with fat herniating into the maxillary sinus and the inferior rectus hanging into the defect. Forced duction testing under anaesthesia before repair confirms restriction on the affected side. Planning proceeds: transconjunctival approach with lateral canthotomy for access, subperiosteal dissection along the orbital floor back to a stable posterior ledge — the posterior and medial ledges are the keystones, since an implant resting on unstable or missing ledges will migrate into the sinus. A titanium mesh is cut to overlap the ledges by a few millimetres without touching the infraorbital nerve or impinging on the muscle cone, and is fixed to the infraorbital rim. Forced duction is repeated: free. Volume is restored enough that the globe sits level. Postoperative care includes ice, elevation, nasal decongestants, instructions not to blow the nose, and — above all — ophthalmological review of vision in the first hours, because retrobulbar haemorrhage announces itself as pain plus a hard, proptosed globe with falling vision.
Where students slip
Three slips recur. First, treating the radiology report as the indication: a small defect with no diplopia, no enophthalmos and free motility is managed conservatively — surgery is driven by function and measurements, not the picture alone. Second, forgetting the medial wall: floor-only repair in a combined floor-medial blowout leaves the volume deficit uncorrected, and enophthalmos persists. Third, underestimating timing — the student who writes "operate electively at convenience" loses the mark, because fat fibroses in the sinus within weeks and late correction of enophthalmos is far harder. Indian exam pattern favours "indications of orbital floor repair" and "approaches to the orbit" as short notes, and the viva trap is naming the orbital emergency: not enophthalmos, not diplopia, but retrobulbar haemorrhage threatening vision, with canthotomy-cantholysis as the answer.
Frequently asked questions
When does an orbital floor fracture need surgical reconstruction?
Large defects (about half the floor or more), persistent diplopia with positive forced duction, enophthalmos of 2 mm or greater, or early enophthalmos with a medially based fracture.
Which approach avoids an external scar and how is access widened?
The transconjunctival approach; access increases with a lateral canthotomy, and a transcaruncular extension reaches the medial wall.
Why repair within about two weeks?
Herniated fat and muscle fibrose inside the sinus as healing proceeds, fixing enophthalmos and making late dissection difficult and results poorer.
What is the forced duction test?
Intraoperative grasping of the inferior rectus insertion and rotation of the globe to test restriction; positive before repair and free after indicates released entrapment.
How is postoperative retrobulbar haemorrhage managed?
As an emergency: open the wound, evacuate clot, and perform lateral canthotomy with inferior cantholysis, with urgent ophthalmological support to save vision.