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

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.

Orthodontic expansion of a collapsed lesser segment should be performed before alveolar bone grafting. The orthodontic device which achieves that expansion will also reduce the surgeon’s access to the palate and alveolus. That device should be replaced before surgery with a retaining appliance including:

• Fixed bands on the maxillary first molar teeth
• 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.

When no residual palatal fistula is identified, the operation proceeds with the bone graft from the labial side. The same is the case if there is an opening but no actual communication to the nose (a blind ended sinus).

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.

In the presence of a narrow palatal fistula from front to back, the margins of the fistula are incised.

If possible the mucosa is then turned inwards and the edges are sutured to each other to create a nasal layer. Sometimes this is done after raising palatal flaps because of the improved access.

In order to achieve closure of the oral layer, the incisions around the fistula are extended to create one or two palatal mucoperiosteal flaps which are raised and approximated.

The flaps are then sutured to each other and to the surrounding palatal tissues over the nasal repair and the fistula.

The final anterior sutures are only placed after the alveolar bone grafting has been carried out. The labial flap is actually sutured to the anterior palatal flaps.

When the fistula is large, two palatal flaps are normally used. It is usually necessary for the flaps to be advanced as well as moved medially. This can only be achieved if the flaps are mobilized well and freed to some extent posteriorly.

In this situation the palatal flaps are raised as described above, but the subperiosteal dissection is extended posteriorly on either side of the greater palatine neurovascular bundle.

The palatal flaps are then partially divided posteriorly with careful protection of the greater palatine vessels. This allows the flaps to be advanced sufficiently to cover the fistula without tension.

The nasal layer is now repaired.

The flaps are then sutured anteriorly both to each other and to the surrounding anterior palatal tissues over the nasal repair and the fistula. This is best effected using 3.0 and 4.0 resorbable sutures mostly as horizontal mattress sutures.

The final anterior sutures are only placed after the bone grafting has been carried out. The labial flap is actually sutured to the anterior palatal flaps.

The labio-buccal alveolar soft tissues on the lesser and medial segments are injected with loca anaesthetic for vasoconstrictor for hemostasis.

A vertical elliptical incision is performed around the labial fistula if present.

In the absence of a fistula, a vertical incision over the alveolar cleft, or a marginal incision with vertical release away from the cleft is performed.

The incision is extended laterally on the lesser segment in the gingival margin around the necks of the teeth posteriorly to the anterior part of the permanent first molar tooth. That incision is then extended upwards and backwards into the buccal sulcus and brought forwards by about 5 mm to give the appearance of a hockey stick.

On the medial side of the cleft, the incision proceeds also around the gingival margin of the erupted teeth on the greater segment including the two permanent central incisors.

The two 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 the 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 cleft is excised.

Pearl: Sometimes there has been an attempt at bony bridging across the alveolar cleft. Such bone is usually quite thin and serves little function. However, it does limit access to the alveolar cleft. It is usually best to remove such bony bridges in order to proceed as described.

The nasal floor mucosa is repaired with resorbable sutures. It is important to try to achieve this repair at the same vertical level as the nasal floor on the non-cleft side.

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 of oxidized cellulose as a barrier.

Cancellous bone harvested from the anterior iliac crest is then inserted into the alveolar defect. The soft bone fragments are condensed into the entire 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 lesser segment flap so that it can be easily stretched over the bone graft area. This is achieved by dividing the periosteum horizontally with a scalpel on the inner and superior aspect of the lesser segment mucoperiosteal flap.

The lesser segment mucoperiosteal flap is advanced to cover the bone grafts and the soft tissues are repaired.

The advancement of the lesser 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.

If a palatal fistula repair was carried out earlier in the procedure, the lesser segment flap is 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.