The genial bone advancement trephine system (GBAT™) (Stryker Leibinger Corporation, Kalamazoo, Minnesota, U.S.) attempts to alleviate tongue base obstruction by advancing the genial tubercle. This modality is a modification of the rectangular mandibular osteotomy with genioglossus advancement. The rationale and indications for the GBAT procedure are the same as for traditional genio-glossus advancement.
Identification of the genial tubercle is essential to perform the surgery. A circular osteotomy is created in the mandible with the provided trephine (12 mm or 14 mm). The bone segment with the attached genioglossus muscle is advanced and secured to the anterior mandible with a rigid plate (111). The surgeon must ensure that the mandible has sufficient size to accommodate the osteotomy without violating the apices of the tooth roots and the inferior border of the mandible.
As this technique is a simple modification of existing genioglossus advancement, one would expect similar outcomes. Miller et al. studied 35 patients who underwent the GBAT procedure with simultaneous UPPP for SDB. The RDI and apnea index were reduced by 70%. Furthermore, the lowest oxygen desaturation increased from 80% to 88% and the posterior airway space increased by 4.7 mm. Overall, the cure rate was 67% (111). Studies have demonstrated subjective improvement in SDB with the GBAT procedure (112). However, long-term objective studies have not documented the success rate of the GBAT technique when used as primary treatment for SDB.
GBAT was developed as a device which would allow a one-step osteotomy and advancement of the genial tubercle. The intention is to allow the surgeon to perform the osteotomy with greater ease and speed. While the device is effective in capturing the genial tubercle, there are significant complications (111-113). Major complications have been noted to be as high as 15% (111). These complications include exposure of the hardware, persistent infection and hematoma of the floor of the mouth requiring drainage. The potential for tooth root injury and pathologic fracture of the mandible exists. Other minor complications noted in traditional genioglossus surgery can occur with the GBAT system. However, the most worrisome complication is avulsion of the genioglossus muscle by the trephine. The circular motion of the trephine places the muscle at greater risk of avulsion as compared to the rectangular osteotomy technique.
Although the GBAT system is capable of capturing the genial tubercle and has an acceptable rate of cure, it does not offer a significant advantage versus traditional surgery. Traditional genioglossus osteotomy can be performed in a similar amount of time. Furthermore, the GBAT system lacks the tactile sensation provided by a sagittal saw, which could potentially result in trauma to the floor of the mouth and muscle avulsion. Lastly, once the genioglossus muscle is avulsed, it is exceedingly difficult to salvage the surgery.
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