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Oral and Maxillofacial Surgery - NEETMDS- courses
Oral and Maxillofacial Surgery

Rigid Fixation

Rigid fixation is a surgical technique used to stabilize fractured bones.

Types of Rigid Fixation

Rigid fixation can be achieved using various types of plates and devices, including:

  1. Simple Non-Compression Bone Plates:

    • These plates provide stability without applying compressive forces across the fracture site.
  2. Mini Bone Plates:

    • Smaller plates designed for use in areas where space is limited, providing adequate stabilization for smaller fractures.
  3. Compression Plates:

    • These plates apply compressive forces across the fracture site, promoting bone healing by encouraging contact between the fracture fragments.
  4. Reconstruction Plates:

    • Used for complex fractures or reconstructions, these plates can be contoured to fit the specific anatomy of the fractured bone.

Transosseous Wiring (Intraosseous Wiring)

Transosseous wiring is a traditional and effective method for the fixation of jaw bone fractures. It involves the following steps:

  1. Technique:

    • Holes are drilled in the bony fragments on either side of the fracture line.
    • A length of 26-gauge stainless steel wire is passed through the holes and across the fracture.
  2. Reduction:

    • The fracture must be reduced independently, ensuring that the teeth are in occlusion before securing the wire.
  3. Twisting the Wire:

    • After achieving proper alignment, the free ends of the wire are twisted to secure the fracture.
    • The twisted ends are cut short and tucked into the nearest drill hole to prevent irritation to surrounding tissues.
  4. Variations:

    • The single strand wire fixation in a horizontal manner is the simplest form of intraosseous wiring, but it can be modified in various ways depending on the specific needs of the fracture and the patient.

Other fixation techniques

Open reduction and internal fixation (ORIF):
Surgical exposure of the fracture site, followed by reduction and fixation with plates, screws, or nails

Closed reduction and immobilization (CRII):
Manipulation of the bone fragments into alignment without surgical exposure, followed by cast or splint immobilization

Intramedullary nailing:
Insertion of a metal rod (nail) into the medullary canal of the bone to stabilize long bone fractures

External fixation:
A device with pins inserted through the bone fragments and connected to an external frame to provide stability
 
Tension band wiring:
A technique using wires to apply tension across a fracture site, particularly useful for avulsion fractures

 

 

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Microvascular Trigeminal Decompression (The Jannetta Procedure)

Microvascular decompression (MVD), commonly known as the Jannetta procedure, is a surgical intervention designed to relieve the symptoms of classic trigeminal neuralgia by addressing the underlying vascular compression of the trigeminal nerve. This procedure is particularly effective for patients who have not responded to medical management or who experience significant side effects from medications.

Overview of the Procedure

  1. Indication:

    • MVD is indicated for patients with classic trigeminal neuralgia, characterized by recurrent episodes of severe facial pain, often triggered by light touch or specific activities.
  2. Anesthesia:

    • The procedure is performed under general anesthesia to ensure the patient is completely unconscious and pain-free during the surgery.
  3. Surgical Approach:

    • The surgery is conducted using an intraoperative microscope for enhanced visualization of the delicate structures involved.
    • The arachnoid membrane surrounding the trigeminal nerve is carefully opened to access the nerve.
  4. Exploration:

    • The trigeminal nerve is explored from its entry point at the brainstem to the entrance of Meckel’s cave, where the trigeminal ganglion (Gasserian ganglion) is located.
  5. Microdissection:

    • Under microscopic and endoscopic visualization, the surgeon performs microdissection to identify and mobilize any arteries or veins that are compressing the trigeminal nerve.
    • The most common offending vessel is a branch of the superior cerebellar artery, but venous compression or a combination of arterial and venous compression may also be present.
  6. Decompression:

    • Once the offending vessels are identified, they are decompressed. This may involve:
      • Cauterization and division of veins that are compressing the nerve.
      • Placement of Teflon sponges between the dissected blood vessels and the trigeminal nerve to prevent further vascular compression.

Outcomes and Efficacy

  • Immediate Pain Relief:

    • Most patients experience immediate relief from facial pain following the decompression of the offending vessels.
    • Reports indicate rates of immediate pain relief as high as 90% to 98% after the procedure.
  • Long-Term Relief:

    • Many patients enjoy long-term relief from trigeminal neuralgia symptoms, although some may experience recurrence of pain over time.
  • Complications:

    • As with any surgical procedure, there are potential risks and complications, including infection, cerebrospinal fluid leaks, and neurological deficits. However, MVD is generally considered safe and effective.

Classes of Hemorrhagic Shock (ATLS Classification)

Hemorrhagic shock is a critical condition resulting from significant blood loss, leading to inadequate tissue perfusion and oxygenation. The Advanced Trauma Life Support (ATLS) course classifies hemorrhagic shock into four classes based on various physiological parameters. Understanding these classes helps guide the management and treatment of patients experiencing hemorrhagic shock.

Class Descriptions

  1. Class I Hemorrhagic Shock:

    • Blood Loss: 0-15% (up to 750 mL)
    • CNS Status: Slightly anxious; the patient may be alert and oriented.
    • Pulse: Heart rate <100 beats/min.
    • Blood Pressure: Normal.
    • Pulse Pressure: Normal.
    • Respiratory Rate: 14-20 breaths/min.
    • Urine Output: >30 mL/hr, indicating adequate renal perfusion.
    • Fluid Resuscitation: Crystalloid fluids are typically sufficient.
  2. Class II Hemorrhagic Shock:

    • Blood Loss: 15-30% (750-1500 mL)
    • CNS Status: Mildly anxious; the patient may show signs of distress.
    • Pulse: Heart rate >100 beats/min.
    • Blood Pressure: Still normal, but compensatory mechanisms are activated.
    • Pulse Pressure: Decreased due to increased heart rate and peripheral vasoconstriction.
    • Respiratory Rate: 20-30 breaths/min.
    • Urine Output: 20-30 mL/hr, indicating reduced renal perfusion.
    • Fluid Resuscitation: Crystalloid fluids are still appropriate.
  3. Class III Hemorrhagic Shock:

    • Blood Loss: 30-40% (1500-2000 mL)
    • CNS Status: Anxious or confused; the patient may have altered mental status.
    • Pulse: Heart rate >120 beats/min.
    • Blood Pressure: Decreased; signs of hypotension may be present.
    • Pulse Pressure: Decreased.
    • Respiratory Rate: 30-40 breaths/min.
    • Urine Output: 5-15 mL/hr, indicating significant renal impairment.
    • Fluid Resuscitation: Crystalloid fluids plus blood products may be necessary.
  4. Class IV Hemorrhagic Shock:

    • Blood Loss: >40% (>2000 mL)
    • CNS Status: Confused or lethargic; the patient may be unresponsive.
    • Pulse: Heart rate >140 beats/min.
    • Blood Pressure: Decreased; severe hypotension is likely.
    • Pulse Pressure: Decreased.
    • Respiratory Rate: >35 breaths/min.
    • Urine Output: Negligible, indicating severe renal failure.
    • Fluid Resuscitation: Immediate crystalloid and blood products are critical.

Osteomyelitis of the Jaw (OML)

Osteomyelitis of the jaw (OML) is a serious infection of the bone that can lead to significant morbidity if not properly diagnosed and treated. Understanding the etiology and microbiological profile of OML is crucial for effective management. Here’s a detailed overview based on the information provided.

Historical Perspective on Etiology

  • Traditional View: In the past, the etiology of OML was primarily associated with skin surface bacteria, particularly Staphylococcus aureus. Other bacteria, such as Staphylococcus epidermidis and hemolytic streptococci, were also implicated.
  • Reevaluation: Recent findings indicate that S. aureus is not the primary pathogen in cases of OML affecting tooth-bearing bone. This shift in understanding highlights the complexity of the microbial landscape in jaw infections.

Microbiological Profile

  1. Common Pathogens:

    • Aerobic Streptococci:
      • α-Hemolytic Streptococci: Particularly Streptococcus viridans, which are part of the normal oral flora and can become pathogenic under certain conditions.
    • Anaerobic Streptococci: These bacteria thrive in low-oxygen environments and are significant contributors to OML.
    • Other Anaerobes:
      • Peptostreptococcus: A genus of anaerobic bacteria commonly found in the oral cavity.
      • Fusobacterium: Another group of anaerobic bacteria that can be involved in polymicrobial infections.
      • Bacteroides: These bacteria are also part of the normal flora but can cause infections when the balance is disrupted.
  2. Additional Organisms:

    • Gram-Negative Organisms:
      • KlebsiellaPseudomonas, and Proteus species may also be isolated in some cases, particularly in chronic or complicated infections.
    • Specific Pathogens:
      • Mycobacterium tuberculosis: Can cause osteomyelitis in the jaw, particularly in immunocompromised individuals.
      • Treponema pallidum: The causative agent of syphilis, which can lead to specific forms of osteomyelitis.
      • Actinomyces species: Known for causing actinomycosis, these bacteria can also be involved in jaw infections.

Polymicrobial Nature of OML

  • Polymicrobial Disease: Established acute OML is typically a polymicrobial infection, meaning it involves multiple types of bacteria. The common bacterial constituents include:
    • Streptococci (both aerobic and anaerobic)
    • Bacteroides
    • Peptostreptococci
    • Fusobacteria
    • Other opportunistic bacteria that may contribute to the infection.

Clinical Implications

  • Sinus Tract Cultures: Cultures obtained from sinus tracts in the jaw may often be misleading. They can be contaminated with skin flora, such as Staphylococcus species, which do not accurately represent the pathogens responsible for the underlying osteomyelitis.
  • Diagnosis and Treatment: Understanding the polymicrobial nature of OML is essential for effective diagnosis and treatment. Empirical antibiotic therapy should consider the range of potential pathogens, and cultures should be interpreted with caution.

Osteogenesis in Oral Surgery

Osteogenesis refers to the process of bone formation, which is crucial in various aspects of oral and maxillofacial surgery. This process is particularly important in procedures such as dental implant placement, bone grafting, and the treatment of bone defects or deformities.

Mechanisms of Osteogenesis

Osteogenesis occurs through two primary processes:

  1. Intramembranous Ossification:

    • This process involves the direct formation of bone from mesenchymal tissue without a cartilage intermediate. It is primarily responsible for the formation of flat bones, such as the bones of the skull and the mandible.
    • Steps:
      • Mesenchymal cells differentiate into osteoblasts (bone-forming cells).
      • Osteoblasts secrete osteoid, which is the unmineralized bone matrix.
      • The osteoid becomes mineralized, leading to the formation of bone.
      • As osteoblasts become trapped in the matrix, they differentiate into osteocytes (mature bone cells).
  2. Endochondral Ossification:

    • This process involves the formation of bone from a cartilage model. It is responsible for the development of long bones and the growth of bones in length.
    • Steps:
      • Mesenchymal cells differentiate into chondrocytes (cartilage cells) to form a cartilage model.
      • The cartilage model undergoes hypertrophy and calcification.
      • Blood vessels invade the calcified cartilage, bringing osteoblasts that replace the cartilage with bone.
      • This process continues until the cartilage is fully replaced by bone.

Types of Osteogenesis in Oral Surgery

In the context of oral surgery, osteogenesis can be classified into several types based on the source of the bone and the method of bone formation:

  1. Autogenous Osteogenesis:

    • Definition: Bone formation that occurs from the patient’s own bone grafts.
    • Source: Bone is harvested from a donor site in the same patient (e.g., the iliac crest, chin, or ramus of the mandible).
    • Advantages:
      • High biocompatibility and low risk of rejection.
      • Contains living cells and growth factors that promote healing and bone formation.
    • Applications: Commonly used in bone grafting procedures, such as sinus lifts, ridge augmentation, and implant placement.
  2. Allogeneic Osteogenesis:

    • Definition: Bone formation that occurs from bone grafts taken from a different individual (cadaveric bone).
    • Source: Bone is obtained from a bone bank, where it is processed and sterilized.
    • Advantages:
      • Reduces the need for a second surgical site for harvesting bone.
      • Can provide a larger volume of bone compared to autogenous grafts.
    • Applications: Used in cases where significant bone volume is required, such as large defects or reconstructions.
  3. Xenogeneic Osteogenesis:

    • Definition: Bone formation that occurs from bone grafts taken from a different species (e.g., bovine or porcine bone).
    • Source: Processed animal bone is used as a graft material.
    • Advantages:
      • Readily available and can provide a scaffold for new bone formation.
      • Often used in combination with autogenous bone to enhance healing.
    • Applications: Commonly used in dental implant procedures and bone augmentation.
  4. Synthetic Osteogenesis:

    • Definition: Bone formation that occurs from synthetic materials designed to mimic natural bone.
    • Source: Materials such as hydroxyapatite, calcium phosphate, or bioactive glass.
    • Advantages:
      • No risk of disease transmission or rejection.
      • Can be engineered to have specific properties that promote bone growth.
    • Applications: Used in various bone grafting procedures, particularly in cases where autogenous or allogeneic grafts are not feasible.

Factors Influencing Osteogenesis

Several factors can influence the process of osteogenesis in oral surgery:

  1. Biological Factors:

    • Growth Factors: Proteins such as bone morphogenetic proteins (BMPs) play a crucial role in promoting osteogenesis.
    • Cellular Activity: The presence of osteoblasts, osteoclasts, and mesenchymal stem cells is essential for bone formation and remodeling.
  2. Mechanical Factors:

    • Stability: The stability of the graft site is critical for successful osteogenesis. Rigid fixation can enhance bone healing.
    • Loading: Mechanical loading can stimulate bone formation and remodeling.
  3. Environmental Factors:

    • Oxygen Supply: Adequate blood supply is essential for delivering nutrients and oxygen to the bone healing site.
    • pH and Temperature: The local environment can affect cellular activity and the healing process.

Fixation of Condylar Fractures

Condylar fractures of the mandible can be challenging to manage due to their location and the functional demands placed on the condylar region. Various fixation techniques have been developed to achieve stable fixation and promote healing. Below is an overview of the different methods of fixation for condylar fractures, including their advantages, disadvantages, and indications.

1. Miniplate Osteosynthesis

  • Overview:

    • Miniplate osteosynthesis involves the use of condylar plates and screw systems designed to withstand biochemical forces, minimizing micromotion at the fracture site.
  • Primary Bone Healing:

    • Under optimal conditions of stability and fracture reduction, primary bone healing can occur, allowing new bone to form along the fracture surface without the formation of fibrous tissue.
  • Plate Placement:

    • High condylar fractures may accommodate only one plate with two screws above and below the fracture line, parallel to the posterior border, providing adequate stability in most cases.
    • For low condylar fractures, two plates may be required. The posterior plate should parallel the posterior ascending ramus, while the anterior plate can be angulated across the fracture line.
  • Mechanical Advantage:

    • The use of two miniplates at the anterior and posterior borders of the condylar neck restores tension and compression trajectories, neutralizing functional stresses in the condylar neck.
  • Research Findings:

    • Studies have shown that the double mini plate method is the only system able to withstand normal loading forces in cadaver mandibles.

2. Dynamic Compression Plating

  • Overview:

    • Dynamic compression plating is generally not recommended for condylar fractures due to the oblique nature of the fractures, which can lead to overlap of fragment ends and loss of ramus height.
  • Current Practice:

    • The consensus is that treatment is adequate with miniplates placed in a neutral mode, avoiding the complications associated with dynamic compression plating.

3. Lag Screw Osteosynthesis

  • Overview:

    • First described for condylar fractures by Wackerbauer in 1962, lag screws provide a biomechanically advantageous method of fixation.
  • Mechanism:

    • A true lag screw has threads only on the distal end, allowing for compression when tightened against the near cortex. This central placement of the screw enhances stability.
  • Advantages:

    • Rapid application of rigid fixation and close approximation of fractured parts due to significant compression generated.
    • Less traumatic than miniplates, as there is no need to open the joint capsule.
  • Disadvantages:

    • Risk of lateralization and rotation of the condylar head if the screw is not placed centrally.
    • Requires a steep learning curve for proper application.
  • Contraindications:

    • Not suitable for cases with loss of bone in the fracture gap or comminution that could lead to displacement when compression is applied.
  • Popular Options:

    • The Eckelt screw is one of the most widely used lag screws in current practice.

4. Pin Fixation

  • Overview:

    • Pin fixation involves the use of 1.3 mm Kirschner wires (K-wires) placed into the condyle under direct vision.
  • Technique:

    • This method requires an open approach to the condylar head and traction applied to the lower border of the mandible. A minimum of three convergent K-wires is typically needed to ensure stability.

5. Resorbable Pins and Plates

  • Overview:

    • Resorbable fixation devices may take more than two years to fully resorb. Materials used include self-reinforced poly-L-lactide screws (SR-PLLA), polyglycolide pins, and absorbable alpha-hydroxy polyesters.
  • Indications:

    • These materials are particularly useful in pediatric patients or in situations where permanent hardware may not be desirable.

Nasogastric Tube (Ryles Tube)

nasogastric tube (NG tube), commonly referred to as a Ryles tube, is a medical device used for various purposes, primarily involving the stomach. It is a long, hollow tube made of polyvinyl chloride (PVC) with one blunt end and multiple openings along its length. The tube is designed to be inserted through the nostril, down the esophagus, and into the stomach.

Description and Insertion

  • Structure: The NG tube has a blunt end that is inserted into the nostril, and it features multiple openings to allow for the passage of fluids and air. The open end of the tube is used for feeding or drainage.

  • Insertion Technique:

    1. The tube is gently passed through one of the nostrils and advanced through the nasopharynx and into the esophagus.
    2. Care is taken to ensure that the tube follows the natural curvature of the nasal passages and esophagus.
    3. Once the tube is in place, its position must be confirmed before any feeds or medications are administered.
  • Position Confirmation:

    • To check the position of the tube, air is pushed into the tube using a syringe.
    • The presence of air in the stomach is confirmed by auscultation with a stethoscope, listening for the characteristic "whoosh" sound of air entering the stomach.
    • Only after confirming that the tube is correctly positioned in the stomach should feeding or medication administration begin.
  • Securing the Tube: The tube is fixed to the nose using sticking plaster or adhesive tape to prevent displacement.

Uses of Nasogastric Tube

  1. Nutritional Support:

    • Enteral Feeding: The primary use of a nasogastric tube is to provide nutritional support to patients who are unable to take oral feeds due to various reasons, such as:
      • Neurological conditions (e.g., stroke, coma)
      • Surgical procedures affecting the gastrointestinal tract
      • Severe dysphagia (difficulty swallowing)
  2. Gastric Lavage:

    • Postoperative Care: NG tubes can be used for gastric lavage to flush out blood, fluids, or other contents from the stomach after surgery. This is particularly important in cases where there is a risk of aspiration or when the stomach needs to be emptied.
    • Poisoning: In cases of poisoning or overdose, gastric lavage may be performed using an NG tube to remove toxic substances from the stomach. This procedure should be done promptly and under medical supervision.
  3. Decompression:

    • Relieving Distension: The NG tube can also be used to decompress the stomach in cases of bowel obstruction or ileus, allowing for the removal of excess gas and fluid.
  4. Medication Administration:

    • The tube can be used to administer medications directly into the stomach for patients who cannot take oral medications.

Considerations and Complications

  • Patient Comfort: Insertion of the NG tube can be uncomfortable for patients, and proper technique should be used to minimize discomfort.

  • Complications: Potential complications include:

    • Nasal and esophageal irritation or injury
    • Misplacement of the tube into the lungs, leading to aspiration
    • Sinusitis or nasal ulceration with prolonged use
    • Gastrointestinal complications, such as gastric erosion or ulceration

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