02 applied anatomy recipe for safe dissection
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In the name of Allah, The Most In the name of Allah, The Most CompassionateCompassionate, , The Most MercifulThe Most Merciful
Applied anatomy of the orbit. Applied anatomy of the orbit. The recipe for safe dissectionThe recipe for safe dissection
Muhammad Azhar SheikhMuhammad Azhar SheikhProf: Oral & Maxillofacial SurgeonProf: Oral & Maxillofacial Surgeon
Islamic Int’l Dental College & Allied HospitalsIslamic Int’l Dental College & Allied Hospitals
Orbital fracturesOrbital fractures
Orbital fractures are common
Proper repair is key to restoring normal facial appearance and function
Concerns due to critical structures – eye Concerns due to critical structures – eye ball and contents of SOF, IOF and Optic ball and contents of SOF, IOF and Optic NerveNerve
Bony OrbitBony Orbit
Orbital Fracture & EyeOrbital Fracture & Eye
Documentation of the condition of the eye before and after surgery is critical.
Young patients with small floor fractures, particularly when experiencing severe pain or nausea, must be suspected of having an entrapped inferior rectus muscle.
Mean Values of important structuresMean Values of important structuresRontal Rontal et al.et al.
Infra-orbital foramen to midpoint of IOF Infra-orbital foramen to midpoint of IOF - 24mm- 24mm
Ant lacrimal crest to ant ethmoidal foramen Ant lacrimal crest to ant ethmoidal foramen - 24mm- 24mm
Ant lacrimal crest to Medial aspect of optic canal Ant lacrimal crest to Medial aspect of optic canal - 42mm- 42mm
FZ suture to superior Orbital fissure FZ suture to superior Orbital fissure - 35mm- 35mm
Supraorbital notch to SOFSupraorbital notch to SOF - 40mm- 40mm
Supraorbital notch to superior aspt of orbital canal Supraorbital notch to superior aspt of orbital canal - 45mm- 45mm
DissectionDissection
No bone removal behind Post ethmoidal No bone removal behind Post ethmoidal foramen – this is 30 mm from anterior foramen – this is 30 mm from anterior lacrimal crest.lacrimal crest.
Perisoteum elevation – line extending from Perisoteum elevation – line extending from FZS to FES medially upto 30mm from FZS to FES medially upto 30mm from supraorbital rim without risking any supraorbital rim without risking any structure passing through superior orbital structure passing through superior orbital fissure fissure
Summary Summary (Randal et al.)(Randal et al.)
Superiorly & Medially – 30mm from superior Superiorly & Medially – 30mm from superior orbital rim and anterior lacrimal crestorbital rim and anterior lacrimal crest
Inferiorly & laterally – 25mm from outer rimInferiorly & laterally – 25mm from outer rim
Care – medial canthal ligament, lacrimal Care – medial canthal ligament, lacrimal apparatus, pulley of superior oblique muscle, apparatus, pulley of superior oblique muscle, supraorbital NV bundles, Structures attached supraorbital NV bundles, Structures attached to whitnall’s tubercle and origin of IO muscle.to whitnall’s tubercle and origin of IO muscle.
Age & Gender VariationAge & Gender Variation
The orbital floor angle was greater in males than in females, and in children than in adults. That is steeper in males and children
The location of the lowest point of the orbital floor moves postero-inferiorly with increasing age.
NAGASAO et al. Journal of Cranio-Maxillofacial Surgery (2007) 35, 112–119
Deep Orbit Deep Orbit Evans and Webb. BJOMS 2007Evans and Webb. BJOMS 2007
Reliable landmarks are available
that are based on the relations of
anatomical structures within the
orbit rather than absolute
distances.
Evans and Webb. BJOMS 2007Evans and Webb. BJOMS 2007
The anatomical landmarks of the deep orbit are both hard and soft tissue structures: – the infraorbital nerve;
– the inferior orbital fissure;
– the greater wing of the sphenoid; and
– the orbital plate of the palatine bone.
Surgical LandmarksSurgical LandmarksEvans and Webb. BJOMS 2007Evans and Webb. BJOMS 2007
IO nerve run parallel IO nerve run parallel to medial wallto medial wall
It does not go to Optic It does not go to Optic nerve - safenerve - safe
Follow the nerve until Follow the nerve until inferior orbital fissure. inferior orbital fissure.
Orbital plate of palatine boneOrbital plate of palatine bone
The orbital plate of the palatine bone provides a constant and reliable landmark in the medial orbital floor.
Reconstruction of the floor of the orbit does not need to extend beyond this.
PearlsPearls
Muscle entrapment does not occur in large fractures, but muscle herniation does.
Floor implants should be placed far enough posterior to the orbital rim that they are not palpable.
Approximately 1 cm of floor fracture will allow the eye to move posteriorly about 1 mm
SummarySummarySo-called safe distances, and the subperiosteal plane of dissection within the orbit, do have a role, but are best considered as adjuncts to orbital dissection rather than absolutes.
Used in conjunction with the anatomical landmarks of the deep orbit, safe and reproducible dissection within the orbit is possible in every case of non-ballistic injuries to the orbit, no matter the extent of orbital disruption.
Retrobulbar Hemorrhage Retrobulbar Hemorrhage Signs and SymptonsSigns and Symptons
PainPain
Decreasing visual acuityDecreasing visual acuity
Diplopia ( if vision preserved)Diplopia ( if vision preserved)
Proptosis (often acute onset)Proptosis (often acute onset)
Retrobulbar HemorrhageRetrobulbar HemorrhageTreatment - MedicalTreatment - Medical
IV mannitol (200ml of a 20% sol)IV mannitol (200ml of a 20% sol)
IV acetazolamide (Diamox) 500mgIV acetazolamide (Diamox) 500mg
IV papaverine 40mgIV papaverine 40mg
IV hydrocortisone 100mgIV hydrocortisone 100mg
If no improvement within 20 minutes, surgical If no improvement within 20 minutes, surgical
decompression is necessarydecompression is necessary
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