Bone scintigraphy in evaluating the viability of composite bone grafts revascularized by microvascular anastomoses, conventional autogenous bone grafts, and free non-revascularized periosteal grafts.

We studied the value of bone scintigraphy in the assessment of anastomotic patency and bone-cell viability in free bone grafts revascularized by microvascular anastomoses in twenty-seven dogs. The dogs were divided into three different groups, and scintigraphy was carried out using technetium-labeled methylene diphosphonate in composite bone grafts revascularized by microvascular anastomoses, conventional autogenous bone grafts, and periosteal grafts placed in different recipient beds. The viability of the grafts was evaluated by histological examination and fluorescence microscopy after triple labeling with oxytetracycline on the first postoperative day, alizarin complexone on the fourth postoperative day, and DCAF on the eleventh postoperative day. A positive scintiscan within the first week following surgery indicated patent microvascular anastomoses, and histological study and fluorescence microscopy confirmed that bone throughout the graft was viable. A positive scintiscan one week after surgery or later does not necessarily indicate microvascular patency or bone-cell survival, because new bone formed by creeping substitution on the surface of a dead bone graft can result in this finding.

Microvascular free bone transfer with revascularization of the medullary and periosteal circulation or the periosteal circulation alone. A comparative experimental study.

UNLABELLED: Two different types of vascularized rib grafts presently are used in clinical practice and as experimental models for investigations on free microvascular bone transfer: the posterior rib graft, including both medullary and periosteal blood supply to the bone; and the posterolateral segmental rib graft, supplied by periosteal vessels alone, Complete survival of bone after successful revascularization of the posterior type of graft is well established, but this graft has the disadvantage of a complicated dorsal dissection which has limited its clinical use. Instead, many microsurgeons have utilized the posterolateral rib segment, which is easy and safe to excise although its viability and adequate microcirculation have not yet been confirmed. In nine large dogs, we compared the viability and vascularity of bone after transfer of the two types of bone grafts by histological methods, fluorochrome bone-labeling, microangiography, and technetium scintigraphy. The grafts were transferred to the subcutaneous fat tissue in the groin, where blood supply was reconstituted by microvascular anastomoses to local donor vessels. The results suggest that a bone transplant with revascularization of periosteal only established a collateral circulation to medullary vessels, and that there is no difference in viability of the two kinds of grafts. CLINICAL RELEVANCE: The technique of transferring whole bone segments by microvascular anastomoses of their vascular pedicles has been employed clinically either by preserving the periosteal blood supply alone or by preserving the medullary and the periosteal blood supply. This study demonstrates that the preservation of the periosteal blood supply alone can result in complete bone-graft survival even when the graft is placed in a poorly vascularized tissue bed.

Reconstruction of mandibular defects after radiation, using a free, living bone graft transferred by microvascular anastomose. An experimental study.

In a previous publication we described the replacement of a mandibular defect by a free, composite rib graft, transferred by microvascular anastomoses of the posterior intercostal vessels to donor vessels in the neck. We now present data which demonstrate that successful results can be achieved even after radical mandibular radiation. This technique, done in dogs, has obvious implications in the management of oral cancer in man.

Mechanical anastomosis of small arteries and veins with the unilink apparatus: a histologic and scanning electron microscopic study.

A new method for mechanical anastomosis of small vessels--the Unilink device--has been tested in 23 rabbits. A total of 81 arterial and venous anastomoses were performed. One of the arterial anastomoses were thrombotized, while the remaining 80 anastomoses were fully patent at 2 or 16 weeks. The repair process at the anastomotic site was very rapid both in arteries and veins. The endothelialization was complete at 2 weeks, but a marked atrophy of the media was noted in the arterial anastomoses. The same phenomenon was observed in the venous anastomosis, but to a much lesser degree. Thrombus formation was extremely rare, and the atrophy of the media did not seem to affect the patency rate. The experiment has confirmed that the Unilink method provides a very safe, fast, and simple way to perform microvascular anastomoses.

Molded vascularized osteoneogenesis: a preliminary study in rabbits.

The clinical application of free vascularized bone grafting techniques in reconstructive surgery has limitations with respect to available donor sites and configuration of the graft. In this study, we were able to produce a vascularized bone graft with a predetermined size and shape by the use of titanium chambers implanted into the groins of rabbits. Forty adult New Zealand white rabbits were included in this study. In all animals, bone fragments were harvested from the iliac crests and placed within a titanium chamber. The chamber was positioned in the groin with the saphenous vessels passing through the chamber longitudinally in contact with the bony fragments. In half the animals, a segment of periosteum was harvested from the tibia and sutured around the vessels with the cambium layer facing the bone fragments. Sacrifices were performed at 4, 8, 12, and 16 weeks to examine the chamber contents. At all time periods, the contents completely filled the chamber, and the saphenous vessels remained patent. Histologic evaluation showed remodeling of the bone fragments as early as 4 weeks concomitant with a sprouting vascular network demonstrable with microangiography. Fluorochrome bone labels documented new bone formation within the chamber. These changes were progressive to week 12, but the 16-week specimens appeared to be undergoing resorption.

Long term evaluation of the unilink anastomotic system. A study with light and scanning electron microscopy.

The long term effects of the Unilink mechanical microvascular anastomosis in terms of anastomotic patency and histological changes in the vessel wall were evaluated in 10 rabbits. Both carotid arteries and facial veins were divided and reanastomosed with the Unilink device. At death two years later all 40 anastomoses were fully patent, with histological changes similar to those described previously after 16 weeks, that is, normal endothelial lining, but almost total atrophy of the media at the anastomotic site. The thinning of the vessel wall at the anastomosis caused neither occlusions nor aneurysms during the observation period.

The "bottle brush": a new concept for uncemented anchorage of bone implants. Preliminary mechanical and biomechanical studies.

We present a new concept for bone of implants, the "bottle brush". It may be suitable for joint prostheses, dental or percutaneous implants, or other devices fixed into bone. Mechanical pullout studies in artificial brass cavities of different sizes and shapes and implantation studies in 20 rabbits, have been successfully carried out. Further experimental and clinical studies are in progress.

Clinical experience with the Unilink/3M Precise microvascular anastomotic device.

The Unilink/3M Precise anastomotic device for microvascular anastomoses has been evaluated in 38 critical anastomoses in 26 selected patients. The microvascular anastomosis was usually completed within three minutes by a single surgeon. There was only one failure, when an arterial anastomosis clotted because of a technical error. In all patients tissue survival was dependent on patent mechanical anastomoses (critical anastomoses) and the follow-up period was more than three years.

Microvascular anastomosis of interpositional vein grafts with the UNILINK system. A comparative experimental study.

Vein segments from the posterior facial vein of the rabbit were surgically isolated and re-anastomosed, either by manual suture technique or by the use of a new mechanical anastomotic device, the UNILINK apparatus. The purpose of the study was to compare anastomotic patency and time required for an orthotopic vein grafting procedure, when the two techniques were used. In the grafts anastomosed with the UNILINK technique, both clinical and histological evaluation showed 100% patency, while 20% of the sutured grafts showed impaired flow as a result of occlusive thrombosis. When the mechanical device was used, the full procedure was completed within one third of the time, as compared to suture anastomoses.

Anastomosis of small veins with suture or Nakayama's apparatus. A comparative study.

In controlled experiments, the posterior facial veins in the rabbits neck (diameter 1.5-2.0 mm) were repaired, either by manual suture with 10-0 nylon or by the use of Nakayama's ring pin stapler. The so-called Nakayama "animal" rings, made from metal alloy, as well as the "human" rings, made from tantalum, were employed. A Nakayama anastomosis was performed in only one-third of the time required to complete a suture anastomosis. Evaluation of anastomotic patency was carried out after 7 days, and the vessels were examined histologically in serial sections. Veins anastomosed by the Nakayama technique had a statistically significant lower rate of early thrombosis than the sutured veins, while no difference was found in the occurrence of late thrombosis. The histological analysis showed a perfect endothelium-to-endothelium coaptation in the Nakayama anastomoses, and endothelium covered the anastomotic site in one week. In suture anastomoses the histological picture was more complex, with disintegration of the layers of the vessel wall and hyaline degeneration betweeen sutures. The "animal" rings almost constantly caused local phlebitis, but these changes were not reflected in the patency rates at one week.

The importance of a maintained medullary blood supply for the survival of revascularized free bone grafts. Preliminary studies.

The importance of an intact medullary blood supply for bone cell survival in free microvascular bone transfers was investigated in 8 beagle dogs. Through a total osteotomy and incision of the surrounding soft tissues, the posterior part of the ninth rib was completely isolated on the intercostal artery and vein. In four of the dogs medullary blood supply to this rib segment was blocked by a semitotal osteotomy near the proximal end of the rib. At sacrifice (one day and 1, 2 and 4 weeks after the operation) bone survival in the isolated rib segment was evaluated by fluorochrome bone labeling, histology and microangiography. The results suggest that the bone segment can survive on the periosteal blood supply alone, with eliminated medullary supply, but further studies are necessary.

Blood flow and scanning electron microscope study on venous microvascular anastomoses with Nakayamas apparatus and manual suture.

Endothelium repair and blood flow changes after microvascular anastomoses in rabbit neck veins (diameter 1.5-2.5 mm) with either Nakayamas apparatus or manual suture were studied with scanning electron microscope and electromagnetical flowmeter. The healing process, which was very rapid, was examined at varying intervals from the day of surgery to four weeks postoperatively. Complete endothelialization was evident after one week. The blood flow was unimpaired by anastomosis with Nakayama rings, whereas in the suture group reduction in blood flow followed immediately after surgery. This reduction was however transient and blood flow was normalized two hours postoperatively.

Normal and retrograde blood supply to the body of the mandible in the dog. I. A new method for selective multicolor arterial perfusion, combined with microangiography and histology.

An experimental study was performed to evaluate a method for selective, multicolor arterial perfusion. In seven adult beagle dogs the lingual, facial and mandibular arteries on one side were cannulated and perfused selectively with different colored perfusates (Microfil and Colorpaque). Identification of the perfusates was achieved using a clearing technique combined with microradiography and histology. With this method, the vascular territories of the body of the mandible and its adjacent tissue could then be identified separately.

Normal and retrograde blood supply to the body of the mandible in the dog. II. The role played by periosteo-medullary and symphyseal anastomoses.

An experimental study was carried out in 8 dogs to delineate the blood supply to the body of the mandible under normal conditions and when the central (medullary) circulation was blocked. A vascular blocking technique combined with selective arterial perfusion using different colored perfusates was used. The results were based on an evaluation of cleared specimens, microradiography and histology. Under normal conditions, the inferior alveolar artery was shown to be the sole source of perfusate to the entire mandibular body, marginal gingiva and the subperiosteal layer, without any contribution from facial artery branches. Several perfused symphyseal anastomoses were found. When the medullary circulation was blocked, retrograde perfusion was evident only in the medullary bone of the frontal region 30 min. after blocking. Marked periosteal and symphyseal vascularity and an increased medullary perfusion were seen 3 days later. 30 days after vascular blocking, perfusion was demonstrated throughout the entire bone including dental pulps. The facial artery was found to be the source of the retrograde perfusion through symphyseal and periosteo-medullary anastomoses in cases with blocked central (medullary) circulation.

Reconstructive microsurgery--a review.

We present some important current applications of reconstructive microsurgery. This field is expanding rapidly and the techniques are finding application in many branches of surgery. There is a pressing need for educational programs and training in microsurgery, as well as for continued research. Many of the procedures reviewed here have already been shown to substantially reduce costs, shorten hospitalization, and lessen patient disability; and as a result, several conventional procedures have been out-dated. We have stressed the concept that this is team surgery. To cover the needs of replantation and emergency free flaps around the clock, several microsurgeons must work together in established centers, and the team must possess expertise from all the involved surgical specialities. This may imply revision of many organizational aspects of patient care. Replantation centers would provide the necessary educational bases and give an impetus to the development of microsurgery.

The UNILINK instrument system for fast and safe microvascular anastomosis.

A new instrument system for fast and safe mechanical microvascular anastomosis is presented. It can be used for both end-to-end and end-to-side anastomosis of small arteries and veins and has the potential for use in other small tubular structures. With moderate training, the surgeon can perform the full microvascular anastomosis within 2 to 3 minutes. The device has proved successful in animal studies and in the clinic, with overall patency rates of about 98% in both arteries and veins.

Microvascular surgery. Techniques and applications in plastic surgery.

Methods of anastomosing small blood vessels are presented, together with an account of the authors' own experiences in the field of microvascular surgery. Practical suggestions are made to avoid pitfalls. The modern literature on experimental and clinical applications of microvascular technique in plastic and reconstructive surgery is reviewed. An extensive bibliography is offered as an aid to the interested reader.

Bone formation in a free, living bone graft transferred by microvascular anastomoses. A quantitative microscopic study using fluorochrome markers.

Bone labeling studies with fluorochrome markers (oxytetracycline and DCAF) were carried out in fifteen dogs in which the posterior portion of the ninth rib was transferred, by means of microvascular anastomoses, to a defect fashioned in the mandible. Seven of the dogs received preoperative radiation of the mandible in order to study the performance of the revascularized graft in radiated tissue. In nine animals the bone grafts were labeled in the subperiosteal, the cortical and the endosteal parts, as opposed to the non-labeling of conventional free bone grafts. Determination of the linear bone formation rate in seven dogs (five non-radiated and two radiated), with the use of a scanning microscope photometer, showed no significant difference between the growth rate in the grafts and that in three other skeletal sites studied.