Numerical Values to Remember

• Implant torque: 10 – 20 N/cm
• Lateral force test: 5 lb
• Failed implant mobility: >1mm horizontal or <500gm force
• CO₂ laser necrosis zone: ~500 microns (continuous) vs <100 microns (pulsed)
• Scar revision wait: 6 – 12 months minimum
• Scar maturation: 4 – 24 months

Key Diagnostic Tests

• Bowstring test: NOE fractures (medial canthal ligament)
• Torque testing: Implant osseointegration
• Percussion test: Implant stability

Most Common/Frequent

• Most frequent orbital fracture: Floor medial to infraorbital canal
• Most useful implant failure sign: Loss of crestal bone
• Greatest ectropion risk: Subciliary incision
• Most recent laser delivery: Hollow wave guide technology

Treatment Hierarchies

Parotid Duct Injury: Location determines treatment Scar Management: Timing is crucial Laser Parameters: Pulse manipulation reduces tissue damage

Memory Aids:

• RSTA: Reflection, Scatter, Transmission, Absorption (laser interactions)
• 4 P's: Photothermal, Photoablative, Photochemical, Photoacoustic (tissue reactions)
• Implant Forces: "10 – 20 torque, 5 lb lateral, < 500gm = fail"

Champy Technique of Fracture Stabilization

The Champy technique, developed by Champy et al. in the mid-1970s, is a method of fracture stabilization that utilizes non-compression monocortical miniplates applied as tension bands. This technique is particularly relevant in the context of mandibular fractures and is based on biomechanical principles that optimize the stability and healing of the bone.

Key Principles of the Champy Technique

1. Biomechanical Considerations:

   • Tensile and Compressive Stresses: Biomechanical studies have shown that tensile stresses occur in the upper border of the mandible, while compressive stresses are found in the lower border. This understanding is crucial for the placement of plates.
   • Bending and Torsional Forces: The forces acting on the mandible primarily produce bending movements. In the symphysis and parasymphysis regions, torsional forces are more significant than bending moments.

2. Ideal Osteosynthesis Line:

   • Champy et al. established the "ideal osteosynthesis line" at the base of the alveolar process. This line is critical for the effective placement of plates to ensure stability during the healing process.
   • Plate Placement:
     • Anterior Region: In the area between the mental foramina, a subapical plate is placed, and an additional plate is positioned near the lower border of the mandible to counteract torsional forces.
     • Posterior Region: Behind the mental foramen, the plate is applied just below the dental roots and above the inferior alveolar nerve.
     • Angle of Mandible: The plate is placed on the broad surface of the external oblique ridge.

3. Tension Band Principle:

   • The use of miniplates as tension bands allows for the distribution of forces across the fracture site, enhancing stability and promoting healing.

Treatment Steps

1. Reduction:

   • The first step in fracture treatment is the accurate reduction of the fracture fragments to restore normal anatomy.

2. Stabilization:

   • Following reduction, stabilization is achieved using the Champy technique, which involves the application of miniplates in accordance with the biomechanical principles outlined above.

3. Maxillomandibular Fixation (MMF):

   • MMF is often used as a standard method for both reduction and stabilization, particularly in cases where additional support is needed.

4. External Fixation:

   • In cases of atrophic edentulous mandibular fractures, extensive soft tissue injuries, severe communication, or infected fractures, external fixation may be considered.

Classification of Internal Fixation Techniques

• Absolute Stability:

  • Rigid internal fixation methods, such as compression plates, lag screws, and the tension band principle, fall under this category. These techniques provide strong stabilization but may compromise blood supply to the bone.

• Relative Stability:

  • Techniques such as bridging, biologic (flexible) fixation, and the Champy technique are classified as relative stability methods. These techniques allow for some movement at the fracture site, which can promote healing by maintaining blood supply to the cortical bone.

Biologic Fixation

• New Paradigm:
  • Biologic fixation represents a shift in fracture treatment philosophy, emphasizing that absolute stability is not always beneficial. Allowing for some movement at the fracture site can enhance blood supply and promote healing.
• Improved Blood Supply:
  • Not pressing the plate against the bone helps maintain blood supply to the cortical bone and prevents the formation of early temporary porosity, which can be detrimental to healing.

• Normal clotting time: 8 – 15 minutes.
• Platelet – rich plasma (1 unit): Raises platelet count by 7,000 – 10,000/μL.
• Fresh frozen plasma (150 mL): Contains 200 μ factors VIII & IX, 400 mg fibrinogen.
• Cryoprecipitate: Contains factors VIII, XIII, vWF, fibrinogen.
• DIC marker: Elevated D – dimers.
• Hemophilia factor levels: Majority have < 5%.
• Surgery in hemophilia: Raise factor levels to 50 – 75%.

Joint Lubrication Mechanisms

Weeping Lubrication

• Occurs at high loads
• Hydrostatic pressure > osmotic pressure
• Water squeezed from extracellular matrix
• Contributes to joint surface lubrication

Boundary Lubrication

• Occurs under low loads

Cartilage Loading Physiology

• Joint movement → increased internal hydrostatic pressure
• When hydrostatic pressure exceeds proteoglycan osmotic pressure
• Water expulsion from extracellular matrix occurs

Postoperative Airway Obstruction

Causes

• Hematoma: Expanding neck hematoma
• Edema: Laryngeal or facial swelling
• Vocal cord paralysis: Recurrent laryngeal nerve injury
• Foreign body: Gauze, blood clots

Management

• Assessment: Rapid evaluation of obstruction level
• Position: Sitting up if conscious, stable
• Suction: Remove blood/debris if visible
• Medications: Steroids for edema, epinephrine for anaphylaxis
• Definitive: Secure airway if conservative measures fail

Anaphylaxis

Recognition

• Rapid onset: Minutes after exposure
• Skin: Urticaria, angioedema
• Respiratory: Bronchospasm, laryngeal edema
• Cardiovascular: Hypotension, tachycardia

Treatment

• Epinephrine: 0.3-0.5mg IM (1:1000)
• Airway: May need emergency surgical airway
• Fluids: Aggressive IV resuscitation
• Antihistamines: H1 and H2 blockers
• Steroids: Prevent biphasic reaction

Laryngospasm

Triggers

• Stimulation: Light anesthesia, secretions
• Irritants: Blood, gastric contents
• Medications: Propofol, succinylcholine

Treatment

• Positive pressure: Gentle bag-mask ventilation
• Larson's maneuver: Pressure at laryngospasm notch
• Succinylcholine: 0.25-0.5 mg/kg if severe
• Intubation: May be necessary if persistent

• Facial nerve location: Below SMAS and parotidomasseteric fascia.
• Jaw angle pressure: Damages 7th cranial nerve.
• Temporal bone transverse fracture: Commonly involves facial nerve.
• Nerve of pterygoid canal: Formed by greater & deep petrosal nerves.
• Tympanomastoid fissure: Stable landmark for locating facial nerve trunk.