Alveolar bone grafting

It is important to perform a bone grafting operation to insert bone into the alveolar cleft defect in order to:

• Convert the maxilla into one bony structure
• Provide bone into which the permanent maxillary canine tooth can erupt
• Assist in the reconstruction of the nasal floor
• To repair labial and palatal fistulae
• Provide some support to the alar base
• Enable orthodontic alignment of teeth
• Provide a solid maxillary structure if later orthognathic surgery is required
• In older patients, to provide a substructure for the insertion of dental implants or other prosthetic rehabilitation

Note: In the bilateral complete cleft lip and palate case, the bone of the premaxilla will generally be attached only to the inferior aspect of the nasal septum. Its blood supply is therefore precarious. Considerable care has to be exercised therefore in handling the premaxilla.

The majority of cleft teams prefer to bone graft between the ages of 8 to 10 years to provide bone into which the permanent canine can erupt and to support adjacent teeth.

A small number of cleft units practice very early bone grafting in the first year or two of life. This is a controversial area as there is insufficient data on its effect on alveolar bone survival into adolescence or on maxillary growth.

There are many potential donor sites for alveolar bone grafting. The most commonly used site is the anterior iliac crest.

For details on how to harvest the cancellous bone from the anterior iliac crest, please click here.

In the incomplete cleft and in patients with clefts of the lip and the alveolus alone, there is less likely to be a palatal fistula that needs to be repaired. In addition there is usually to some extent a bony palatal shelf. The alveolar bone grafting procedure is exactly the same as for the complete cleft patient but is usually easier.

Most bilateral cleft lip and palate cases require some orthodontic treatment before alveolar bone grafting. The principal aim of such treatment is to ensure that all three alveolar segments are well aligned (the lateral segments are sufficiently expanded and the premaxilla is in a good central position). Following this the alveolar segments need to be stabilized. The orthodontic device however which achieves that stabilization can make it very difficult for the surgeon to access the palate and alveolus. That device should be replaced before surgery with a retaining appliance including:

• Fixed bands on the maxillary first molar teeth
• Bands or brackets on premaxillary teeth if present
• A strong labial arch wire connecting these bands or brackets and the alveolar segments
• Lateral arms to maintain expansion
• A removable transpalatal arch wire (this can be removed at the beginning of surgery and replaced at the end)

A cleft gag is inserted and the palate inspected for fistulae using a large lacrimal probe.

If there is no communication to the nose, it may not be necessary to carry out an anterior palate repair.

Any fistula communicating with the nose ideally requires a two layer closure.

The anterior palate is injected with local anaesthetic with vasoconstrictor for hemostasis.

The nose is gently cleaned with cotton buds soaked in an antiseptic solution.

Note: This description is for the typical bilateral complete cleft case. Depending on the precise original cleft and the surgery carried out, there can be considerable variation in fistulae and the technique has to be modified accordingly.

An incision is made in the marginal oral mucosa around the fistula as shown. The mucoperiosteum is elevated for a couple of mm sufficient to allow the edges to be approximated as a nasal layer.

Two palatal flaps are outlined as shown. Because of the shape and the size of the fistula, it is usually necessary for these flaps to be advanced anteriorly as well as moved medially. This can only be achieved if the flaps are mobilized well and freed as much as possible posteriorly.

The palatal flaps are raised subperiosteally. Over the palatal cleft the oral mucoperiosteal flaps are sharply divided from the nasal mucosa.

The subperiosteal dissection of the palatal flaps is extended posteriorly on either side of the greater palatine arteries. The flaps are then partially divided posteriorly with careful protection of the greater palatine arteries. This allows the flaps to be advanced sufficiently to cover the anterior fistula without tension.

The margins of the fistulae are then sutured to each other to create a nasal layer.

The flaps are then sutured anteriorly both to each other, to the premaxillary mucoperiosteum and to the surrounding anterior palatal tissues over the nasal repair and the fistula.

Although the palatal flaps can be sutured to premaxilla at this time, the final anterior palatal sutures are only placed after the bone grafting has been carried out. The labio buccal flaps are actually sutured to the anterior palatal flaps.

The labio-buccal alveolar soft tissues on the lateral and premaxillary segments are injected with local anaesthetic with vasoconstrictor for hemostasis.

Vertical elliptical incisions are made around the labial fistula as medial as possible close to the premaxilla.

In the absence of a fistula, medially placed vertical incisions are made over the alveolar clefts close to the premaxilla.

The incisions are extended laterally on the lateral segments in the gingival margin around the necks of the teeth as far posteriorly as the anterior part of the permanent first molar teeth. Those incisions are then extended upwards and backwards into the buccal sulcus and brought forwards by about 5 mm to give the appearance of a hockey stick.

It is critically important that no incision is made of the premaxillary gingival margin medially. The mucoperiosteum should be preserved over the premaxilla in order not to compromise its blood supply.

The two lateral mucoperiosteal flaps are then raised to expose the alveolar cleft and floor of nose. It is especially important to separate the oral from the nasal mucosa. This separation is done with a scalpel.

When the flaps have been raised, remaining in the alveolar cleft is scar tissue and nasal mucosa attached to the palate.

The two nasal mucosal layers (medial and lateral) are identified and raised with a periosteal elevator from the medial and lateral margins of each bony cleft.

The scar tissue and nasal mucosa remaining in the alveolar cleft then needs to be separated from the palatal tissues by sharp division with a scalpel.

The scar tissue and excess nasal mucosa within the alveolar clefts is excised.

The nasal floor mucosa is repaired with resorbable sutures at as high a level as possible, which is at the level of what would be a normal nasal floor.

When the scar tissue and excess nasal mucosa within the alveolar cleft have been excised, sometimes the nasal mucosa is intact and at approximately the correct height. Clearly, nasal floor repair is not necessary in such a situation.

Pitfall: If too much nasal mucosa is excised it can be difficult to repair the nasal floor. On the other hand, if the nasal floor is too low, it must be mobilized superiorly or excess nasal mucosa excised and repaired to create space for the bone graft.

Pearl: Occasionally the inferior turbinate above the alveolar cleft defect is large and prevents repair of the nasal floor at the correct level. In such a case, a partial inferior turbinectomy (mainly of soft tissue) should be carried out prior to the repair of the nasal floor.

Pearl: If the surgeon is not confident that he or she has a good nasal floor repair, the repair should be covered with a small piece of an absorbable membrane as a barrier.

Cancellous bone harvested from the anterior iliac crest is then inserted into the alveolar defects. The soft bone fragments are condensed into all of the defect.

Pearl: If there is a complete alveolar defect with no anterior bony palatal shelf, it helps to insert a finger behind the anterior palate to provide posterior support while packing the bone.

Pearl: It helps to insert a fairly large piece of bone first, which will not find its way into the nose.

It is extremely important that the closure of the oral layer over the bone graft is completely free from tension. This requires the mobilization of the lateral flaps so that they can be easily stretched over the bone graft areas. This is achieved by dividing the periosteum horizontally with a scalpel on the inner and superior aspect of the lateral segment mucoperiosteal flaps.

The lateral segment mucoperiosteal flaps are advanced to cover the bone grafts and the soft tissues are repaired.

The advancement of the lateral segment flap leaves a soft tissue defect posteriorly over the alveolar bone. This must not be closed and is allowed to heal by secondary intention.

Pearl: When closing a vertical incision, which overlies the bone graft, it is useful to use horizontal mattress sutures.

The same procedure is then carried out on the contralateral side. These illustrations show the completed repair.

If a palatal fistula repair was carried out earlier in the procedure, the lateral segment flaps are also sutured to the anterior part of the palatal flap(s).

Antibiotics
Intravenous antibiotics are always administered during surgery and are generally continued for one to three days postoperatively. If the patient goes home early the antibiotics are continued orally at home.

Analgesics
Potentially the most painful area is the donor site for bone in the anterior iliac crest. In practice long acting local anaesthetic are administered into the donor site at the end of surgery and postoperatively.

Local anaesthetic which has been administrated at the recipient site also helps with postoperative pain control.

Further oral pain medication should also be made available on a regular basis (eg, paracetamol) and for break-through pain.

When bone is harvested from the iliac crest, the patient should be checked for bowel sounds periodically following surgery. Once sounds of gut motility have been confirmed the patient can start to take oral clear fluids.

A sliding scale of fluids and soft food is prescribed for the few days following surgery.

Normally, patients should start to brush their teeth with a small soft children’s toothbrush and toothpaste from the morning after surgery. This should be followed 30-60 min later by a chlorhexidine mouth wash.

The patient should be mobilized as early as possible and absolutely no later than the morning after surgery. They should be encouraged to weight bear on the operated side until they can walk without any limp.

As soon as the patient is eating and walking well and there are no other complications of surgery they should be able to be discharged from hospital.

The patient is usually seen as necessary in the out patient department for review . The healing of all operation sites is checked. Usually, 6 months after surgery a single oblique occlusal radiograph is taken (two for a bilateral case). In some units this radiograph has been replaced with a cone beam CT. The quality of the result of the alveolar bone graft procedure is assessed and documented. The patient’s ongoing cleft care is mapped out.