Biomedical subjects
Publications and source records attributed to B M O'Brien.
Two cases of microvascular great toe transfer for congenital absence of the thumb in children are reported. A rationale and operative details are discussed. A long term follow up is needed, but at this stage the results are most encouraging. There has been no interference with gait.
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An assessment of the results of three techniques of nerve repair. Epineurial repair, Funicular repair with resection of epineurium and Combined Funicular and Epineurial repair. The results were essentially similar.
Two cases are presented in which a severely damaged hand was reconstructed by the simultaneous transfer of two toes using microvascular techniques. A two year evaluation of the functional result is made in both cases. Conventional reconstructive methods have little place in the reconstruction of these severe disabilities.
Microneurovascular flaps from the first web space of the foot offer a solution to upgrade sensibility of the denervated hand. Based on the dorsalis pedis artery, it allows simple dissection and a large vessel for easy and safe anastomosis. Seven cases are presented in which combinations of the first web anatomy for a variety of denervation injuries were used. The technique is ideally suited in those cases where no areas of island flap tissue are available for transfer.
The no-reflow phenomenon was studied following reconstitution of blood flow by microvascular anastomosis in an ischemic and denervated free epigastric flap in the rabbit. Microscopic, histological, angiographic, and hematological studies demonstrated the progressive nature of this obstruction to the peripheral blood flow after increasing periods of ischemia. This obstruction reached a point of irreversibility after 12 hours of ischemia, leading to ultimate death of these flaps. These results are consistent with the hypothesis that an ischemia-induced no-reflow phenomenon is caused by cellular swelling, intravascular aggregation, and the leakage of intravascular fluid into the interstitial space. Similarities between these experimental findings and human observations are made. The clinical importance of early diagnosis and treatment of ischemic tissues is emphasized.
The effects of solution perfusion in the free epigastric flap of the rabbit, after normothermic ischemic periods of 8 hours or 12 hours, have been examined by operative microscopic and histological methods. A smaller group of animals was also studied in which the perfusion was done before the ischemic insult. An ischemia-related obstruction to the peripheral blood flow occurred in the absence of stagnant ischemic blood in this model. Although the 3 perfusion fluids studied were shown to penetrate to all levels of a flap after such an ischemic period, none of them had a beneficial effect on skin survival. However, the solution containing mannitol did have a protective effect on fat survival. Analogies between these experimental findings and the clinical situation are made, and the importance of the early diagnosis and treatment of ischemia in a flap is emphasized.
Microsurgical revascularization in the neck has improved the survival rate of free small-bowel grafts used to replace the cervical oesophagus. Colon vessels are larger than those in the jejunum, and even with naked-eye technique good results have been reported following free colon grafting of the oesophagus. The authors thought it might be possible to achieve even better results using microvascular anastomoses in the neck, and in this way replaced the cervical oesophagus in each of 15 dogs with a free transverse colon autotransplant. Four dogs died during operation and four within three days, two of the latter with graft necrosis. The next seven dogs survived eight days or more, and all their colon grafts were viable. Where patent arteries were demonstrated (three cases) the mucosa and myenteric plexuses of the graft survived. In all four dogs where the arteries were thrombosed or not demonstrated, the mucosa was absent, myenteric plexuses were absent in three, and one graft was grossly stenosed. Among these seven dogs there were three fistulae, one where graft arteries were patent and two where they were not; immediate anastomotic healing was not guaranteed by graft survival or arterial patency.
A segment of tibia 4.5 centimetres long was removed from one hind limb of fifteen dogs. It was then replaced and the main vasculature was restored by a microsurgical technique. In eight controls the segment was replaced without such restoration. In two-thirds of the former cases the microvascular reconstruction was successful; the rate of infection was found to be reduced, bone union was guaranteed and the rate of union accelerated. Success or failure of the reconstruction was clearly demonstrated in five cases by early bone scanning using technetium-labelled polyphosphate.
In this series of 62 free flap transfers, 48 (80%) have been successful. There have been a significant number of vascular complications, 39% of which the majority were arterial thrombosis. Fifty per cent of those which thrombosed were salvaged on exploration and revision of the vessels. The frequency of complications has diminished with experience but they remain significantly high. Free flap surgery demands considerable expertise in both donor site dissection and microvascular technique. Two surgeons with microvascular experience, each with adequate assistance, are preferred and ready availability of operating room is essential. Close postoperative observation and readiness to revise anastomoses are equally important. About 50% of failed free flap sites have been repaired by application of split skin grafts.
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An unsuccessful human fallopian tube transplant is reported. A microsurgical technique is described which initially secured a viable transplant. However, the allograft subsequently died, probably as a result of rejection. Immunosuppression of the patient caused no complications or difficulties, the donor sharing one HL-A haplotype with the patient. The operative procedure, the risks of immunosuppression, and the ethical aspects of the case are discussed in order to present the problems associated with fallopian tube transplantation.
In a series of 130 digital replantations successful revascularization has been obtained in 74% of cases. Arterial thrombosis is the most common cause (65%) of all failures. A useful digit can be obtained following replantation and the surgery is particularly indicated for amputated thumbs and in hands suffering multiple injuries. Precautionary measures against bleeding are absolutely essential. Primary tendon and nerve repairs are advocated. Vascular occlusion may be corrected by revisional surgery and secondary surgery can improve tendon nerve or joint function.
Ninety-two anastomoses of arteries 0.5 mm in diameter have been performed in rats with an 85-90 per cent patency rate in the second postoperative week. The factors of prime importance in the achievement of high patency rates have been atraumatic handing and meticulous suturing technique. At 1 hour and at 8 to 10 days the patency rates were not statistically different whether 20 per cent magnesium sulphate heparin or normal saline were used. Similar results were obtained with 40 repairs of divided veins averaging 0.4 mm in diameter. These results suggest strongly that clinical microvascular surgery in vessels approximately 0.5 mm in diameter, especially in children, should given results comparable to 1 mm vessel surgery.
To identify an anatomically reliable and functionally acceptable neurovascular free flap for use in hand reconstruction, 50 fresh cadaver feet were dissected under the operating microscope, with particular attention paid to the anatomy of the first web area. A distal communicating artery was seen in 100% of dissections, allowing either dorsal or plantar donor artery inflow to nourish the entire flap area. Because of the ease of dissection, the first dorsal metatarsal or dorsalis pedis is suggested as the donor artery, and a dorsal branch of the greater saphenous venous system is suggested as the donor vein. The deep peroneal nerve was seen to consistently innervate the first web and, along with the plantar digital nerves, is suggested as an anatomically identifiable donor nerve. Either part of the foot first web may be used alone or together as a free flap. When indicated further dorsal skin may be incorporated into the web flap to expand its application. Two-point discrimination studies of the lateral plantar surface of the great toe in 50 normal individuals showed an average of 11.2 mm. This was significantly better as a potential donor flap than the medial dorsum of the foot where the average was 32 mm. A single case demonstrating the application of this flap in hand reconstruction is presented.
Microlymphatic surgery appears to have a worthwhile clinical application in the treatment of secondary obstructive lymphedema. We prefer 3 or more lymphaticovenous anastomoses at, or above, the elbow; otherwise ablative procedures are recommended. In the selected cases there are some advantages of anastomoses over surgical reduction procedures: (1) the incidence of postoperative cellulitis is significantly less; (2) the microlymphatic techniques are applicable to both upper and lower limbs and perhaps could be extended to localized cases of obstructive lymphedema following trauma and congenital constriction bands. Considerable experience in microvascular surgery is required for doing this type of work. A long-term evaluation of the results of microlymphatic surgery in obstructive secondary lymphedema is required before judging its potential--especially in view of the fluctuating history of lymphedema--but the results reported are encouraging.
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