Abstract
Microvascular couplers have been introduced as an alternative method for anastomosis in mandibular reconstruction. This study included 64 patients who had undergone free flap reconstruction for mandibular defects and had been scheduled for follow-up at 1, 3, 6, and 12 months. After completion of the tumour resection and harvesting of the osteomyocutaneous flap, appropriate preparation of both ends of the vessels was performed for microsurgery. Single-vein anastomoses were performed in 35 patients and double-vein anastomoses in 29 patients. Except for 75 couplers used for venous anastomosis only, both arterial and venous anastomoses were performed using the coupler in seven flaps. No flap failures occurred in these cases, resulting in an overall flap success rate of 100%. As expected, anastomoses were completed successfully using the coupler in 78 out of 80 attempted cases (97.5%). Additional large and randomized studies are needed to compare the outcomes of coupler anastomoses to those of traditional sutured anastomoses, and to define to what extent this would present cost-savings per procedure.
Functional mandibular reconstruction remains a great challenge for oral and maxillofacial surgeons. Currently, vascularized fibula and iliac crest flaps are the most common choices for mandibular reconstruction. Hand-sewn anastomosis has been the traditional and standard technique for these microsurgical reconstructions. However, this intimal-penetrating technique poses a risk for intravascular thrombosis, which can lead to eventual flap loss in some patients.
In recent years, microvascular couplers have been introduced as an alternative method for anastomosis in free flap head and neck reconstruction. The use of microvascular couplers has been proven to be a safe, time-saving, and reliable non-suture technique with a high patency rate. Despite many reports of the successful use of these devices for venous anastomosis in soft tissue reconstruction, there have been no large reports focusing on the efficacy of arterial microanastomosis with couplers in mandibular reconstruction.
Here, we present our experiences with the successful use of 80 couplers for microsurgical venous and arterial anastomoses in 64 patients who underwent mandibular reconstruction with free fibula or iliac crest flaps, highlighting the surgical procedure, its role in flap survival, the advantages and disadvantages, and the functional results.
Materials and methods
Patients
The present study included 64 patients who underwent free flap reconstruction for mandibular defects at the Department of Oral and Maxillofacial – Head and Neck Oncology, Hospital Of Stomatology, Wuhan University from September 2013 to October 2014. Upon institutional review board approval, a retrospective review was conducted based on patient age, gender, tumour location, pathological diagnosis of the tumour, flap type, recipient vessels, method of vascular anastomosis, coupler size, arteries and veins associated with the coupler, operation time, the results of reconstruction, complications encountered, and the survival rate.
Surgical procedure
All surgical procedures were performed using a ‘two-team’ approach: an extirpative surgery team and a reconstructive surgery team. After completion of the tumour resection and harvesting of the osteomyocutaneous flap, appropriate preparation of both ends of the vessels was performed for microsurgery. The Microvascular Anastomotic Coupler System (Synovis Micro Companies Alliance Inc., Birmingham, AL, USA) was used for the microanastomoses, in the standard fashion and in accordance with the manufacturer’s instructions. In brief, the anastomosis was performed in the following five steps: (1) placement of vessels in proximity to the recipient vessels occluded using vascular clamps; (2) determination of the coupler size using a coupler measuring gauge; (3) pulling and pinning of the vessels to the coupler; (4) rotation of the instrument knob to mate the vessel ends, and (5) securing the two rings in opposition using a fine haemostat before separation of the instrument from the rings. During the vascular coupling, the vessels were rinsed repeatedly with heparinized saline (2 ml of heparin and 10 ml of lidocaine mixed into 200 ml of normal saline). After a careful inspection of patency and appropriate drainage placement, autograft fixation and subsequent suture of the incision were finally performed ( Fig. 1 ).
Postoperatively, flap monitoring was performed by clinical examination and bedside external Doppler every 30 min for the first 24 h, every 1 h for the next 24 h, and every 4 h in the following days. If necessary, low-dose low molecular weight heparin was used as postoperative anticoagulation therapy. Patients were usually discharged home between postoperative days 7 and 10, and scheduled for follow-up at 1, 3, 6, and 12 months.
Results
Clinical data of the 64 consecutive patients are given in Table 1 .
| Characteristics | Cases (percentage %) |
|---|---|
| Gender | |
| Male | 28 (43.8) |
| Female | 36 (56.2) |
| Diagnosis | |
| Squamous cell carcinoma (SCC) | 20 (31.3) |
| Ameloblastoma | 24 (37.5) |
| Keratocystic odontogenic tumour (KCOT) | 6 (9.4) |
| Ossifying fibroma | 2 (3.1) |
| Adenoid cystic carcinoma (ACC) | 2 (3.1) |
| Complex odontoma | 1 (1.6) |
| Vascular malformation | 1 (1.6) |
| Neurinoma | 1 (1.6) |
| Dentinogenic ghost cell tumour | 1 (1.6) |
| Epithelioid haemangioendothelioma | 1 (1.6) |
| Mucoepidermoid carcinoma | 2 (3.1) |
| Secondary reconstruction | 3 (4.7) |
| Flap usage | |
| Fibula flap | 35 (54.7) |
| Iliac flap | 29 (45.3) |
Eighty mechanical anastomoses using the Microvascular Anastomotic Coupler System and 74 hand-sewn anastomoses were performed in 64 free osteomyocutaneous flaps. All microanastomoses were performed in an end-to-end fashion. Single-vein anastomoses were performed in 35 patients and double-vein anastomoses in 29 patients. Except for 75 couplers used for venous anastomosis only, both arterial and venous anastomoses were performed using the coupler in seven flaps.
For the 75 venous anastomoses using the coupler, the most common recipient veins were the external jugular veins and anterior facial vein, but the branch of the internal jugular vein, common facial vein, superior thyroid vein, posterior facial vein, anterior jugular vein, and lingual vein were also used. Six arterial couplings were performed for deep circumflex iliac artery (DCIA) flaps ( Fig. 2 ) and only one for a fibula flap ( Fig. 3 ) because the peroneal arteries had atherosclerotic plaques and a thicker vascular wall in most of the patients ( Table 2 ). In seven arterial anastomoses with the coupler, the recipient arteries were the facial artery or the superior thyroid artery. The coupler size used for venous anastomosis varied from 1.5 to 4.0 mm, and for arterial anastomosis from 1.5 to 2.5 mm ( Table 3 ).
| Microvascular anastomosis | Vein only | Both vein and artery |
|---|---|---|
| Flap used | ||
| Fibula flap | 30 (39) | 2 (6) |
| Iliac flap | 29 (29) | 3 (6) |
| Number of anastomosed veins | ||
| Single | 35 | |
| Double | 29 | |
| Coupler size | Number (percentage %) |
|---|---|
| Veins | |
| 1.5 mm | 8 (10) |
| 2.0 mm | 15 (18.8) |
| 2.5 mm | 20 (25) |
| 3.0 mm | 20 (25) |
| 3.5 mm | 6 (7.5) |
| 4.0 mm | 4 (5) |
| Artery | |
| 1.5 mm | 2 (2.5) |
| 2.0 mm | 4 (5) |
| 2.5 mm | 1 (1.2) |
Intraoperative and postoperative complications are summarized in Table 4 . No flap failures occurred in these cases, resulting in an overall flap success rate of 100%. The anastomosis was completed within 5 min following vascular preparation for veins and within 8 min for arteries. Anastomoses were completed successfully using the coupler in 78 out of 80 attempted cases (97.5%). None of the patients developed a venous thrombosis. There was no coupler abandonment due to the device being broken, but two couplers were abandoned due to the ring falling off the instrument. However, two couplers were discarded intraoperatively and sutured anastomoses were performed because of a twist in the vein. One venous anastomosis was redone intraoperatively using the coupler for the second anastomosis because of an anastomotic leak. There was one intraoperative arteriospasm that was revised without further flap complications. Three patients developed postoperative neck haematomas (2–3 h postoperatively), which required immediate explorative operations without affecting the flap survival.
