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Fixation of Vascularized Bone Flaps

last modified on: Tue, 12/12/2023 - 16:58

return to: Microvascular Surgery Protocols

see also: Case example - Anterior mandibular reconstruction with osteocutaneous fibula free flap

Note: last updated before 2017

GENERAL CONSIDERATIONS

  1. Indications
    1. Most osseous free tissue transfer flaps will require some contouring and subsequent fixation of the bone in place at the recipient site. In certain cases, contouring of the bone will be all that is required; in other cases, the bone will need to be contoured with osteotomies that will have to be fixated in addition to fixing the bone into the recipient site.
  2. Contraindications
    1. See Microvascular Surgery General Considerations
  3. Pertinent Anatomy
    1. It is important to be aware of the anatomic pattern through which blood reaches a particular bone when manipulating a vascularized bone flap. This information for a specific flap may suggest a more favorable location or orientation for the periosteal cuts and osteotomies.
    2. Blood supply to bone
      1. Nutrient artery of the diaphysis
      2. Perforating arteries of the metaphyses
      3. Periosteal plexus of vessels (supplies the outer one-third of the cortex, adequate for bone survival; the major source of blood supply to most vascularized bone flaps)
    3. The periosteal plexus may have 1 or more of 3 different types of configurations. Note that these are roughly similar to the blood supply of cutaneous flaps.
      1. Axial periosteal, running parallel to the harvested bone
      2. Musculoperiosteal perforators
      3. Fascioperiosteal vessels
    4. There are 2 donor sites for every flap, the right and left. This is frequently important in selecting the bone best configured for a given reconstruction. The right or left handedness of the patient and the recipient vessel location are also variables that need to be considered in planning the reconstruction.

PREOPERATIVE EVALUATION

  1. Evaluation
    1. See Individual flap protocols.
  2. Potential Complications
    1. Postoperative occlusal disharmony in the dentate patient
    2. Poor aesthetic facial contour
    3. Nonunion or delayed union of the flap to native bone
    4. Local infection around hardware requiring removal of the hardware

NURSING CONSIDERATIONS

  1. Room Setup
    1. See Basic Soft Tissue Room Setup
      1. Back table x 2
  2. Instrumentation and Equipment
    1. Standard
      1. Major Instrument Tray 1, Otolaryngology
      2. Major Instrument Tray 2, Otolaryngology
      3. Bipolar Forceps Trays
      4. Hall Micro Sagittal Saw Tray (Pneumatic)
      5. Nerve stimulator control unit and instrument
    2. Special
      1. KLS Free Flap Implant - Instrument Tray
      2. KLS Locking Reconstruction Threadlock Instrument Tray
      3. KLS Oto Trauma Implant - Instrument Tray
      4. Bien Otologic Electric Drill Tray
      5. Varidyne vacuum suction controller
      6. Cummings retractor, large and medium
      7. McKesson mouth prop, adult, large
      8. Molt mouth gag, adult
      9. Minnesota retractor
      10. Shearer retractor
      11. Bone wax
  3. Medications (specific to nursing)
    1. 1% lidocaine with 1:100,000 epinephrine
    2. Antibiotic ointment
  4. Prep and Drape
    1. Standard prep, 10% providone iodine
    2. Drape
      1. Head drape
      2. Towels to square off around incision line
      3. Split sheet
  5. Drains and Dressings
    1. Varidyne vacuum suction drain, 7 mm to 10 mm
  6. Special Considerations
    1. If mental nerve divided, order Microsurgery Instrument Tray, Otolaryngology to reanastomose with nylon 9-0
    2. Tracheotomy may be performed either initially or as part of the procedure
    3. Specific
      1. Appropriate bone cutting tool; this can be an oscillating saw or Midas Rex bone cutting tool, frequently rongeurs are useful.
      2. A hand-held drill is useful for smoothing rough edges if the Midas-Rex is not used.
      3. The particular method used is a matter of personal preference and may depend on the dental status of the patient (see below). The appropriate plating system should be available. The most frequent methods used are listed below. On occasion a combination of the techniques listed below are used (eg, miniplates and lag screws).
        1. Interosseous wires
        2. 2.0 mm mandibular plates or 2.0 mm miniplates
        3. 2.4 mm mandibular plate
        4. Locking screw reconstruction plates.
      4. It is frequently useful to have template material available in the operating room.
    4. The donor site should be prepped at the same time as the head and neck.
    5. See Individual flap protocols

OPERATIVE PROCEDURE

  1. It is sometimes possible to perform as much contouring and plate application as possible while the flap remains in the donor site perfusing. This is frequently dependent on the complexity of the reconstruction.
  2. The bone contouring and stabilization should be done prior to microvascular anastomosis of the flap (see exception below). A back table should be set up where this work can be done.
  3. In cases with a dentate patient, establishing pre-resection occlusion of the remaining dentition is crucial. In these cases, a 2.4 mm mandibular plate or locking screw reconstruction plate is used. The plate is contoured to span the segmental defect prior to making the bone cuts; this is not possible if the buccal cortex cannot be exposed for oncologic reasons. The screw holes in the mandible are drilled, and screws are temporarily inserted. The plate is removed during the segmental resection, and the positions of the bone cuts are marked on the plate. The flap bone is contoured to reestablish the mandibular continuity and fixed to the plate. This may require 1 or more osteotomies in the flap bone. The plate with fixated flap bone is then fixed to the mandible. It is ideal to have at least 2 screws in each segment of flap fixed to the plate. For 2.4 mm mandibular plates, 4 screws in the native mandible at each end of the plate are ideal, but 3 may be adequate. For the locking screw systems, 3 or 4 screw holes at either end of the plate in native mandible is ideal, but 2 may be all that is possible if only the condyle remains.
  4. In edentulous patients, the bone geometry is not as crucial, and a template is used to contour a segment of flap bone that replaces the segmental defect. In these cases, the flap bone osteotomies are fixated with miniplates and lag screws. The flap is fixated to the native mandible with miniplates as well. When using miniplates to fixate the mandible, it is crucial for stability that at least 2 plates be placed across each bone junction. The orientation of these plates should be such that the screws placed in the 2 plates are at 90° to one another. This provides stability in 2 planes and significantly increases the strength of the construct. When miniplates and lag screws are used, it is also crucial that the bone junctions fit together with maximal bone contact. This requires closing osteotomies when creating a curved neomandible from a straight flap bone.
  5. When reconstructing the mandible, the native mandible may also be notched at the inferior border the receive the bone flap in a lock-and-key fashion in order to increase bone surface contact and add further stabilization.
  6. If a reconstruction plate is used, the plate is fixated on top of the flap periosteum. When miniplates are used, they are fixated under the periosteum, and the periosteum is draped back over the plates
  7. Wedge ostectomies are made on the concave side of the bone if the arch of the maxilla or mandible is being reconstructed. This allows maximum bone contact at the ostectomy site. However, this is not possible for scapular bone flaps. Opening osteotomies are created in the convex side of the scapular bone.
  8. An extra 1 cm of bone length should be harvested for each planned ostectomy, and an extra 1 cm should be harvested to allow any needed contouring of the flap bone at the flap-mandible junction. As indicated above, we frequently notch the native mandible to allow greater bone contact and added stability; when this is done, an additional 1 cm is always required.
  9. In the edentulous patient, precise bone cuts utilizing lock-and-key configurations or closing ostectomies that are in effect miter cuts may facilitate the use of lag screws. If lag screws alone are used to fixate a bone-bone junction, a minimum of 2 screws should be used, or 1 screw may be used in combination with a miniplate.
  10. Once the mandible has been contoured and is ready to be fixated to the native mandible flap, soft tissue that will be inset posterior to the mandible may be sutured. This is often much easier to do if the bone has not been plated in position.
  11. In selected cases when the recipient vessels are high in the neck, it may be easier to delay final fixation of the flap in place until after the anastomoses are complete.

POSTOPERATIVE CARE

  1. See Microvascular Surgery General Considerations
  2. Patients are NPO for 7 days if they have had no previous XRT and for 2 weeks if they have had previous radiation.
  3. Liquid diet may be advanced to soft diet as tolerated. Soft diet is maintained for 6 weeks.
  4. Follow up orthopantomogram at 10 to 12 weeks.

REFERENCES

Funk GF. Scapula and parascapular free flaps. Facial Plast Surg. 1996;12:57-63.

Hidalgo DA. Fibula free flap: a new method of mandible reconstruction. Plast Reconst Surg. 1989;84:71-79.

Urken ML, Vickery C, Weinberg H, Buchbinder D, Biller HF. Geometry of the vascular pedicle in free tissue transfers to the head and neck. Arch Otolaryngol Head Neck Surg. 1989;115:954-960.