The optimal sequence of microvascular repair during prolonged clamping in free flap transfer

During free flap transfer, the surgeon may decide to begin with repair of the artery or the vein(s) and to unclamp the first vessel as soon as repair is completed or maintain the clamping of both vessels until completion of all repairs. Complications can lead to prolonged clamping times, potentially increasing the risk of tissue ischemia, vascular damage, and thrombosis. The goals of the present study were to determine whether the sequence of vessel repair and the duration of clamping affect the success of free flap transfer in cases requiring prolonged clamping. Sixty abdominal fasciocutaneous free flaps based on the superficial inferior epigastric vessels were created in Sprague-Dawley rats. To model clinical situations in which prolonged clamping is necessary, the study used a 1-hour delay before the repair of the second vessel. Flaps were randomized into four groups. In group I (n = 15), the artery was repaired first, and the arterial clamp was removed immediately to allow arterial inflow. In group II (n = 15), the arterial repair was first, and the arterial clamp was maintained until completion of venous repair. In group III (n = 15), venous repair was first, with venous clamping maintained until completion of the arterial repair. In group IV (n = 15), initial venous repair was followed by immediate unclamping, before arterial repair. On release of all clamps, the patency of arteries and veins was confirmed immediately and after 1 hour using a "milking" test. On the fifth postoperative day, each flap was assessed for necrosis and for patency of the anastomoses. Of 15 flaps in each group, five (33 percent) failed in group I, four (27 percent) failed in groups II and III, and six (40 percent) failed in group IV. Differences between groups were not statistically significant (p = 0.8). These results demonstrate that in cases requiring prolonged occlusive clamping (2 to 3 hours), factors such as venous congestion, possible clamp injury, and presence of static blood in contact with the new anastomosis have relatively equivalent contributions to the risk of failure. Accordingly, no advantage seems to be gained by beginning with the artery or the vein or by using early or delayed unclamping of the first vessel repaired.     

Thumb reconstruction by free microvascular transfer of an injured index finger

Thumb reconstruction for amputation at the metacarpal phalangeal level was accomplished by microneurovascular transfer of the contralateral damaged index finger ray, including metacarpal phalangeal joint. This transfer accomplished a successful thumb restoration and removed a cumbersome index finger amputation stump, improving function in both hands. This case emphasizes the merits of spare part transfer in hand reconstructive surgery made possible by microneurovascular techniques.     

Microvascular free tissue transfer for treatment of osteoradionecrosis of the maxilla

Head and neck tumors often require radiotherapy as part of the treatment protocol. Although it improves the survival rate in cancer patients, it may cause osteoradionecrosis, especially in the mandible and maxilla. Twelve patients with osteoradionecrosis of the maxilla were treated with microsurgical free tissue transplantations between April of 1996 and August of 2002. There were 10 male and two female patients, with a mean age of 60.2 years. The mean radiotherapy dose was 6674 cGy. The radiation dose could not be traced in three patients because radiotherapy was performed elsewhere. Radical sequestrectomy, soft-tissue debridement, and pathologic proof of no tumor recurrence were performed before microsurgical reconstruction. Free flaps used included the following: anterolateral thigh (n = 7), radial forearm (n = 2), rectus femoris musculocutaneous (n = 2), and supracondylar chimeric (n = 1) flaps. All flaps survived completely and reconstruction succeeded. During a mean 25-month follow-up period, ectropion, plate exposure, and mild infection were encountered in three patients and treated successfully. Radical debridement and obliteration of dead space with well-vascularized tissue are essential for successful treatment of maxillary osteoradionecrosis. The anterolateral thigh flap is most versatile for almost all types of soft-tissue defect reconstruction in the head and neck region.     

Simple maxillary reconstruction using free tissue transfer and prostheses

Prosthetic rehabilitation is essential for maintaining postoperative oral function after maxillary reconstruction. However, the maxillary prosthesis becomes unstable in some patients because of extensive palatomaxillary resection and drooping of the transferred flap. In such patients, maintaining sufficient oral function is difficult, especially if the patient is edentulous. To achieve prosthetic retention, the authors performed microvascular maxillary reconstruction with a slit-shaped fenestration in the midline of the hard palate. Maxillary defects after subtotal or total maxillectomy were reconstructed with rectus abdominis musculocutaneous flaps in five patients. Defects of the nasal lining and palate were reconstructed with the single cutaneous portion of the flap, and a slit-shaped fenestration was left between the cutaneous portion of the flap and the edge of the remaining hard palate. Postoperatively, patients were fitted with maxillary prostheses that had a flat projection for the palatal fenestration. In all patients, the prosthesis was stable enough for mastication and prevented nasal regurgitation. Speech function was rated as excellent on Hirose's scoring system for Japanese speech ability. The authors believe that their method of palatomaxillary reconstruction is both simple and reliable.     

Staged transfer of a free microvascular latissimus dorsi myocutaneous flap using saphenous vein grafts

The use of long vein grafts in the axilla adds a new dimension to the versatility of the latissimus dorsi myocutaneous flap. When suitable recipient vessels are not available for a microvascular anastomosis, long vein grafts can be used in the axilla to double the arc of rotation of the flap, allowing it to cover the buttocks, lower torso, and scalp (Fig. 8). A case is presented in which the latissimus dorsi myocutaneous flap was transferred in stages to cover a large radiation ulcer of the right buttock.     

Prefabrication of composite free flaps through staged microvascular transfer: an experimental and clinical study

The feasibility of prefabricating free flaps by inducing, through the process of staged reconstruction, an arteriovenous bundle and its surrounding fascia to perfuse a selected block of tissue was investigated experimentally and clinically. Sixteen rat knee joints were wrapped with their ipsilateral superficial inferior epigastric (SIE) fascia. In 8 joints, the composite flaps were resected en bloc and were immediately replaced orthotopically pedicled upon the superficial inferior epigastric vessels. In the remaining joints, the resection and orthotopic transfer were performed 2 weeks later. Only the joints in the latter group, which benefited from the staging period, were found to be perfused. The long finger proximal interphalangeal joint of a child was reconstructed by the staged microvascular transfer of his second toe proximal interphalangeal joint. At the first stage, a temporalis fascia flap was wrapped around the toe proximal interphalangeal joint and revascularized to the dorsalis pedis vessels. Six weeks later, the joint and its temporalis fascia envelope were dissected, and the "prefabricated" joint flap was transferred to the hand and revascularized to the wrist vessels. Bony union progressed uneventfully with excellent recovery of the range of motion. We conclude that regardless of the indigenous vascular anatomy, an unlimited array of composite free flaps can be constructed and transferred based on induced large vascular pedicles.     

Flap perfusion after free musculocutaneous tissue transfer: the impact of postoperative complications

In a previous study, the authors found persistence of pedicle blood flow up to 10 years after uncomplicated free latissimus dorsi transfer. In this study, the impact of postoperative complications (hematoma, thrombosis, infection) and successful surgical revision was tested. Since 1982, more than 1200 free tissue transfers have been performed at the authors' institution (Hannover Medical School). Of these, the authors selected two groups of 30 patients each who had received a free latissimus dorsi transfer to the lower leg without microsurgical nerve coaptation for wound coverage. All patients included in this study were carefully selected for clinical homogeneity, with one difference: group I comprised patients who had no postoperative complications after free latissimus dorsi transfer. Group II included only patients with major postoperative complications after the procedure. All flaps in group II survived after successful surgical revision. The arteries, which nourished the lower leg, were visualized and documented by means of a duplex scanner in both groups. Three different time intervals were chosen for measurements of blood flow: 4 to 6 months (groups I.I and II.I), 4 to 6 years (groups I.II and II.II), and 8 to 10 years (groups I.III and II.III). Quantitative measurements of local flap perfusion in milliliters per minute per 100 g tissue were performed by means of the hydrogen clearance technique. In each patient, a total of nine measurements was performed in three phases: phase A, before closing the vascular pedicle by manual compression (n = 3); phase B, with a closed pedicle (n = 3); and phase C, after releasing the vascular pedicle from manual compression (n = 3). Each measurement took approximately 10 minutes. One hundred percent closure of each pedicle in phase B was confirmed by the duplex scanner. Furthermore, all patients were monitored both clinically and by means of the hydrogen clearance technique during phase B for adequate blood supply to the lower leg. Lower leg perfusion showed no statistical differences for phases A, B, and C in all groups of patients. In group I, no statistical differences in local flap perfusion were encountered for phases A and C. In phase B, however, a statistically significant (p < 0.01) complete extinction of local flap perfusion was registered in all patients of group I at the site of the flap's skin paddle. In group II, however, persistent flap perfusion was registered during phase B in up to 50 percent of cases in one subgroup (II.III). No statistically significant alterations of local blood flow were registered in the surrounding tissue of group II during phases A, B, and C. Patients with thrombosis of the venous anastomosis (n = 7) seemed to have the highest incidence of loss of autonomous blood supply through the vascular pedicle (5 out of 11 cases). No inconstant results were found during the repetitive measurements (n = 3) for each patient in each phase. After uncomplicated free tissue transfer, the flap's intact vascular pedicle seems to play an important role in permanent flap survival up to 10 years after the procedure. Postoperative complications after free tissue transfer with successful surgical revision, especially venous thrombosis of the vascular anastomosis, may lead to loss of vascular flap autonomy over time.