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)

A 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

Basic Principles of Treatment of a Fracture

The treatment of fractures involves a systematic approach to restore the normal anatomy and function of the affected bone. The basic principles of fracture treatment can be summarized in three key steps: reduction, fixation, and immobilization.

1. Reduction

Definition: Reduction is the process of restoring the fractured bone fragments to their original anatomical position.

• Methods of Reduction:

  • Closed Reduction: This technique involves realigning the bone fragments without direct visualization of the fracture line. It can be achieved through:
    • Reduction by Manipulation: The physician uses manual techniques to manipulate the bone fragments into alignment.
    • Reduction by Traction: Gentle pulling forces are applied to align the fragments, often used in conjunction with other methods.

• Open Reduction: In some cases, if closed reduction is not successful or if the fracture is complex, an open reduction may be necessary. This involves surgical exposure of the fracture site to directly visualize and align the fragments.

2. Fixation

Definition: After reduction, fixation is the process of stabilizing the fractured fragments in their normal anatomical relationship to prevent displacement and ensure proper healing.

• Types of Fixation:

  • Internal Fixation: This involves the use of devices such as plates, screws, or intramedullary nails that are placed inside the body to stabilize the fracture.
  • External Fixation: This method uses external devices, such as pins or frames, that are attached to the bone through the skin. External fixation is often used in cases of open fractures or when internal fixation is not feasible.

• Goals of Fixation: The primary goals are to maintain the alignment of the bone fragments, prevent movement at the fracture site, and facilitate healing.

3. Immobilization

Definition: Immobilization is the phase during which the fixation device is retained to stabilize the reduced fragments until clinical bony union occurs.

• Duration of Immobilization: The length of the immobilization period varies depending on the type of fracture and the bone involved:

  • Maxillary Fractures: Typically require 3 to 4 weeks of immobilization.
  • Mandibular Fractures: Generally require 4 to 6 weeks of immobilization.
  • Condylar Fractures: Recommended immobilization period is 2 to 3 weeks to prevent temporomandibular joint (TMJ) ankylosis.

•  

Distoangular Impaction

Distoangular impaction refers to the position of a tooth, typically a third molar (wisdom tooth), that is angled towards the back of the mouth and the distal aspect of the mandible. This type of impaction is often considered one of the most challenging to manage surgically due to its orientation and the anatomical considerations involved in its removal.

Characteristics of Distoangular Impaction

1. Pathway of Delivery:

   • The distoangular position of the tooth means that it is situated in a way that complicates its removal. The pathway for extraction often requires significant manipulation and access through the ascending ramus of the mandible.

2. Bone Removal:

   • A substantial amount of distal bone removal is necessary to access the tooth adequately. This may involve the use of surgical instruments to contour the bone and create sufficient space for extraction.

3. Crown Sectioning:

   • Once adequate bone removal has been achieved, the crown of the tooth is typically sectioned from the roots just above the cervical line. This step is crucial for improving visibility and access to the roots, which can be difficult to see and manipulate in their impacted position.

4. Removal of the Crown:

   • The entire crown is removed to facilitate better access to the roots. This step is essential for ensuring that the roots can be addressed without obstruction from the crown.

5. Root Management:

   • Divergent Roots: If the roots of the tooth are divergent (spreading apart), they may need to be further sectioned into two pieces. This allows for easier removal of each root individually, reducing the risk of fracture or complications during extraction.
   • Convergent Roots: If the roots are convergent (closer together), a straight elevator can often be used to remove the roots without the need for additional sectioning. The elevator is inserted between the roots to gently lift and dislodge them from the surrounding bone.

Surgical Technique Overview

1. Anesthesia: Local anesthesia is administered to ensure patient comfort during the procedure.

2. Incision and Flap Reflection: An incision is made in the mucosa, and a flap is reflected to expose the underlying bone and the impacted tooth.

3. Bone Removal: Using a surgical bur or chisel, the distal bone is carefully removed to create access to the tooth.

4. Crown Sectioning: The crown is sectioned from the roots using a surgical handpiece or bur, allowing for improved visibility.

5. Root Extraction:

   • For divergent roots, each root is sectioned and removed individually.
   • For convergent roots, a straight elevator is used to extract the roots.

6. Closure: After the tooth is removed, the surgical site is irrigated, and the flap is repositioned and sutured to promote healing.

Considerations and Complications

• Complications: Distoangular impactions can lead to complications such as nerve injury (especially to the inferior alveolar nerve), infection, and prolonged recovery time.
• Postoperative Care: Patients should be advised on postoperative care, including pain management, oral hygiene, and signs of complications such as swelling or infection.

Axial Compression in Bone Fixation

Axial compression refers to a surgical technique used in the fixation of fractured bones, where the bony ends are brought into close proximity, minimizing the inter-fragmentary gap. This technique is crucial for achieving stable fixation and promoting optimal healing of fractures, particularly in the context of internal fixation using plates and screws.

Key Concepts of Axial Compression

1. Close Proximity of Bony Ends:

   • In axial compression, the fractured ends of the bone are aligned closely together, which is essential for effective healing. The minimal inter-fragmentary gap allows for direct contact between the bone surfaces, facilitating the healing process.

2. Functional Dynamic Forces:

   • During normal activities, such as chewing (masticatory function), dynamic forces are generated. These forces can create stress at the fracture site, which must be countered by the static forces provided by the fixation devices (plates and screws).

3. Static Forces from Plates and Screws:

   • The stability of the fracture fixation relies on the ability of the plates and screws to provide sufficient static forces to counteract the dynamic forces generated during function. This is critical for maintaining the alignment of the fracture and preventing displacement.

4. Plate and Screw Specifications:

   • Plate Thickness: Plates with a thickness of 2 mm are commonly used, as they provide adequate strength and stability while minimizing soft tissue irritation.
   • Screw Specifications: Bi-cortical screws with a diameter of 2.7 mm are typically employed. These screws engage both cortices of the bone, enhancing stability and fixation strength.

5. Principle of Inclined Plane:

   • The design of the holes in the plate and the head of the screws operates on the principle of an inclined plane. This design allows for the application of compressive forces when the screws are tightened, effectively drawing the bony fragments together.
   • As the screws are tightened, they create a compressive force that helps to stabilize the fracture and maintain the alignment of the bone fragments.

Advantages of Axial Compression

• Enhanced Stability: By minimizing the inter-fragmentary gap and providing strong static forces, axial compression enhances the stability of the fracture fixation.
• Promotes Healing: Close approximation of the bony ends facilitates the healing process by allowing for direct contact and reducing the risk of non-union or malunion.
• Functional Restoration: Effective axial compression allows patients to regain function more quickly, as the fixation can withstand the dynamic forces generated during normal activities.

Surgical Considerations for the Submandibular and Parotid Glands

When performing surgery on the submandibular and parotid glands, it is crucial to be aware of the anatomical structures and nerves at risk to minimize complications. Below is an overview of the key nerves and anatomical landmarks relevant to these surgical procedures.

Major Nerves at Risk During Submandibular Gland Surgery

1. Hypoglossal Nerve (CN XII):

   • This nerve is responsible for motor innervation to the muscles of the tongue. It lies deep to the submandibular gland and is at risk during surgical manipulation in this area.

2. Marginal Mandibular Nerve:

   • A branch of the facial nerve (CN VII), the marginal mandibular nerve innervates the muscles of the lower lip and chin. It runs just deep to the superficial layer of the deep cervical fascia, below the platysma muscle, making it vulnerable during submandibular gland surgery.

3. Lingual Nerve:

   • The lingual nerve provides sensory innervation to the anterior two-thirds of the tongue and carries parasympathetic fibers to the submandibular gland via the submandibular ganglion. It is located in close proximity to the submandibular gland and is at risk during dissection.

Anatomical Considerations for Parotid Gland Surgery

• Parotid Fascia:

  • The parotid gland is encased in a capsule of parotid fascia, which provides a protective layer during surgical procedures.

• Facial Nerve (CN VII):

  • The facial nerve is a critical structure to identify during parotid gland surgery to prevent injury. Key landmarks for locating the facial nerve include:
    • Tympanomastoid Suture Line: This is a reliable landmark for identifying the main trunk of the facial nerve, which lies just deep and medial to this suture.
    • Tragal Pointer: The nerve is located about 1 cm deep and inferior to the tragal pointer, although this landmark is less reliable.
    • Posterior Belly of the Digastric Muscle: This muscle provides a reference for the approximate depth of the facial nerve.
    • Peripheral Buccal Branches: While following these branches can help identify the nerve, this should not be the standard approach due to the risk of injury.

Submandibular Gland Anatomy

• Location:

  • The submandibular gland is situated in the submandibular triangle of the neck, which is bordered by the mandible and the digastric muscles.

• Mylohyoid Muscle:

  • The gland wraps around the mylohyoid muscle, which is typically retracted anteriorly during surgery to provide better exposure of the gland.

• CN XII:

  • The hypoglossal nerve lies deep to the submandibular gland, making it important to identify and protect during surgical procedures.