Biomechanical analysis of dorsal plate fixation in proximal phalangeal fractures

The biomechanical properties of three minifragment plate and screw systems were compared to determine whether plate systems primarily designed for maxillofacial reconstruction are biomechanically sound for use in proximal phalangeal fracture fixation. A middiaphyseal transverse osteotomy was created in each of 30 fresh-frozen human proximal phalanges to simulate an unstable fracture. Each osteotomy was then fixed with four 2.0ml screws through one of three different four-hole minifragment plates in a middorsal position. Plating systems tested included a vitallium plate with self-tapping screws (Luhr), a stainless steel plate with tapped screws (Synthes), and a titanium plate with tapped screws (Synthes). Testing was performed to failure in an apex volar three-point bending mode. The titanium-plated phalanges were the stiffest construct and required the greatest load and total energy absorbed to failure. However, only the load to failure for titanium versus stainless steel was significantly different. Therefore, there is no biomechanical disadvantage to using the titanium or vitallium plate and screw systems in the setting of unstable proximal phalangeal fractures.

Microvascular reconstruction of the upper extremity with the rectus abdominis muscle

Large soft-tissue defects of the upper extremity are difficult to reconstruct. Defects in 21 patients (15-75 years old) were treated by free tissue transfer of the rectus abdominis muscle. The defects were the result of trauma or resection of tumor and measured more than 15 x 15 cm. The muscle was transferred on the inferior epigastric pedicle and covered with a skin graft within 48 hours. All transfers were successful, and early soft-tissue healing occurred. This procedure offers the advantages of easy positioning, large donor vessels, and a highly vascular soft tissue reconstruction. The long-term functional and cosmetic results have been excellent.

Development of a genetic system for Eikenella corrodens: transfer of plasmids pFM739 and pLES2

Eikenella corrodens is a Gram-negative microaerophilic rod which is emerging as an important human pathogen. Elucidation of the mechanisms by which it causes disease require efficient methods for the transfer of DNA to E. corrodens. Plasmids pFM739 and pLES2 have been transferred by conjugation from Escherichia coli S17-1 to E. corrodens ATCC 23834 at frequencies of 2.5 x 10(-7) and 2.42 x 10(-7), respectively. In addition, both plasmids could be transferred to four additional, clinical strains of E. corrodens at a similar frequency. The use of bacteriophage T4 as a counterselecting agent is also described.

Preoperative evaluation of giant cell tumors of the radius with magnetic resonance angiography

We report three clinical cases of giant cell tumor of the distal radius in which reconstructions were performed with vascularized fibular grafts. Magnetic resonance angiography, a newer and noninvasive technique, was used in addition to preoperative magnetic resonance imaging. All patients had routine digital subtraction arteriography, with which magnetic resonance angiography compared favorably, demonstrating the carpal arch anatomy and other major vessels at the tumor site. In two patients the trifurcation vessels of both legs were also studied with magnetic resonance angiography before fibular harvest. In one case, the fibula graft was successfully harvested on the basis of the magnetic resonance angiographic findings. In the other case, digital subtraction arteriography had been done to evaluate suspected peripheral vascular disease. In that case magnetic resonance angiography correlated well with the digital subtraction arteriographic study, showing bilateral anterior tibial artery occlusions and patent posterior tibial and peroneal arteries. Magnetic resonance angiography has the potential to replace conventional angiography in preoperative evaluation of upper-extremity tumors.

Cloning, characterization and sequencing of two haemagglutinin genes from Eikenella corrodens

Eikenella corrodens is emerging as an important human pathogen, in both extra-oral and periodontal infections. From a clone bank of Eikenella corrodens chromosomal DNA produced in Escherichia coli JM109, twenty-two clones expressed Eikenella antigens and of these, two expressed functional haemagglutinins. By virtue of different restriction maps and a lack of homology by Southern hybridization, the two cloned fragments encoding the two haemagglutinins have been shown to be distinct. Maxicell analysis revealed that clone 1, carrying plasmid pVKR201, produces three Eikenella proteins, one of 31.5 kDa and two of approximately 14 kDa each. Expression of each of the proteins appears to be under the control of an Eikenella promoter(s). Clone 2, carrying plasmid pVKR301, produces two proteins, one of 93 kDa and the second of 17 kDa. Expression of both of these proteins in E. coli requires the lac promoter in the vector. By preparing a series of subclones and testing each by maxicell analysis and for haemagglutination activity, a functional map of the insert of clone 1 was deduced and the 31.5 kDa polypeptide identified as the haemagglutinin. Using similar methods, the 17 kDa protein was found to be the haemagglutinin of clone 2. The nucleotide sequences of both haemagglutinin genes were determined and are presented. Computer analysis revealed no homology between the two haemagglutinins, and no homology to any previously sequenced proteins. These are the first genes of this genus to be cloned and sequenced.

Cloning and sequencing of two type 4 (N-methylphenylalanine) pilin genes from Eikenella corrodens

Eikenella corrodens is a Gram-negative microaerophilic rod which is gaining recognition as an important human pathogen. We have previously reported the cloning and expression in Escherichia coli of a 3.6 kb Eik. corrodens genomic DNA fragment which encodes a 31.5 kDa haemagglutinin. Maxicell analysis revealed that this fragment also encodes two proteins of approximately 14 kDa. Nucleotide sequencing of the 2.2 kb fragment upstream of the haemagglutinin gene revealed two open reading frames with strong homology to genes encoding pilin subunit proteins of the type 4 or N-methylphenylalanine class. The two pilin genes, ecpA and ecpB, are complete and are expressed in E. coli. Southern analysis of ten additional Eik. corrodens strains revealed that all possess fragments homologous to ecpA. These data represent the first molecular evidence for pili in E. corrodens.

Immunotherapy for metastatic renal cell cancer: effect on the primary tumor

The traditional approach to immunotherapy for metastatic renal cell cancer, to first reduce the tumor burden by nephrectomy and then offer systemic therapy, has been challenged recently. There is mounting evidence that objective responses in the metastatic disease can be achieved without prior nephrectomy, although responses in the primary tumor are much less frequent. We describe our experience that some patients may, in fact, have significant responses in extensive local disease and become surgical candidates after systemic immunotherapy. A 46-year-old patient who presented with a large renal primary tumor and pulmonary metastases was treated with high-dose interleukin 2 therapy. A complete response in the lung and partial response in the primary tumor was achieved. The patient then underwent resection of his primary tumor, and on histological evaluation only minimal residual cancer was present. He has no evidence of disease at 14 months. This case demonstrates that immunotherapy can achieve not only objective responses at metastatic sites but also in the primary tumor.

Alteration of reactivity of native arteries induced by venous graft placement

Occlusion of aortocoronary venous grafts can be due to thrombosis, atherosclerosis, or vasospasm. Investigations have focused on properties of the graft itself, and little is known about the vascular reactivity and function of the native arteries proximal and distal to the vein graft, although spasm of the native artery distal to the graft site has been observed in patients. We hypothesized that the function of the endothelium of the native arteries may be altered after surgery. Autogenous venous grafts were placed in femoral arteries of rabbits to study the reactivity of the native arteries after grafting. Four weeks after graft implantation, the vein graft, ipsilateral vein, and native artery proximal and distal to the graft were removed for in vitro studies. Morphological evaluation by scanning electron microscopy and fluorescence microscopy after labeling with acetylated low density lipoprotein labeled with 1,1'-dioctadecyl-3,3,3',3'-tetramethyl-indocarbocyanine perchlorate indicated the presence of an intact, metabolically active endothelial layer. There was no alteration in the contractile responses to phenylephrine of the arteries, vein grafts, or veins. Precontracted vein grafts, veins, and arterial segments proximal to the grafts relaxed when exposed to endothelium-dependent vasodilators (acetylcholine, arachidonic acid, and substance P), but the native arteries distal to the grafts did not. In bioassay cascade experiments, the distal artery did not release any measurable relaxing factor when exposed to acetylcholine. We conclude that the endothelium of the distal artery did not function normally. The extent and reversibility of altered endothelial function remain to be determined. This observation may help to explain the occurrence of myocardial infarction after aortocoronary bypass grafting in some patients.

High-pressure injection injuries of the hand

High pressure injection trauma to the upper extremity is a rare but potentially limb-threatening injury. The index finger on the non-dominant hand of young male workers is most commonly involved. Injected materials include paint, grease and diesel oil. Prompt recognition and initiation of treatment is necessary if a disastrous outcome is to be avoided. Primary treatment consists of surgical decompression and debridement. Amputation may be necessary. With early aggressive treatment, satisfactory results can be obtained. The use of high-pressure devices in industry has resulted in an unusual but potentially limb-threatening injury to the upper extremity known as the "high-pressure injection injury." This injury is a surgical emergency that demands prompt diagnosis and treatment if a disastrous outcome is to be avoided. The purpose of this paper is to present our recent experience and review the clinical features, evaluation and treatment principles.

Removal of venous endothelium with air

Much research on the activity and half-life of endothelium-derived substances has entailed the removal of endothelium from arteries by mechanical or enzymatic processes. It has been observed that the technique used for the removal of arterial endothelium may profoundly affect smooth muscle function and release of prostanoids by the vessel wall. The function and patterns of regeneration of arterial endothelium have been extensively described, but there is a relative paucity of information about the venous endothelium, due in part to the difficulty of its removal. We developed a technique for removal of the endothelium of rabbit femoral veins by passing a stream of air through the lumen of the vessel to dry and remove the endothelium. The effectiveness of endothelium removal was verified by the lack of in vitro reactivity to endothelium-dependent relaxing substances, examination of frozen sections of vessels, labeled with fluorescent-tagged acetylated low-density lipoprotein, with fluorescent light microscopy and scanning electron microscopy of vessel segments. Air drying effectively removed the endothelium and abolished mechanical responses to endothelium-dependent vasodilators but did not affect the function of the smooth muscle. We propose the use of air to remove endothelium from veins to be used to study endothelium-derived factors since this method achieves complete removal of endothelium without causing detectable damage (morphological or functional) to the remainder of the vessel wall.

Well-differentiated liposarcoma (atypical lipoma) of deep soft tissue of the extremities, retroperitoneum, and miscellaneous sites. A follow-up study of 92 cases with analysis of the incidence of "dedifferentiation"

Ninety-two cases of well-differentiated liposarcoma of deep soft tissue of the extremity, retroperitoneum, and groin with follow-up information of at least 2 years and no evidence of dedifferentiation at the time of diagnosis were studied to determine their long-term behavior. The tumors occurred most commonly in the muscles of the extremity (46 cases), followed by the retroperitoneum (23 cases), groin (14 cases), and miscellaneous sites (nine cases). Tumors in the retroperitoneum recurred in nearly all cases (21 of 23 cases), occasionally caused patient death, and dedifferentiated in four cases (median time to dedifferentiation, 8 years). Tumors in the groin had a similar high recurrence rate (11 of 14 cases), caused death of patients (two of 14 cases), and dedifferentiated (four of 14 cases). In contrast, those in the extremity recurred less frequently (20 of 46 cases) and had no disease-related mortality. Three of 46, however, underwent dedifferentiation (median time to dedifferentiation, 7 years). Of the 11 cases that underwent dedifferentiation, the interval between diagnosis and dedifferentiation ranged from 2 to 18 years (median time, 9 years; average time, 11 years). Six of the 11 patients showed dedifferentiated foci in the first recurrence, and three died of metastatic disease. Our study indicates that the behavior of well-differentiated liposarcomas is strongly influenced by location. Although the prevailing view is that dedifferentiation is restricted to tumors of the retroperitoneum, our study indicates that it is not a site-specific phenomenon, but is more likely a time-dependent phenomenon seen in situations with a high likelihood for clinical persistence of disease for a long period. Dedifferentiation identifies a tumor that is potentially more aggressive; yet the progression of the disease following dedifferentiation may be highly variable and probably depends on a number of factors, including the amount of dedifferentiation and type of therapy. Although atypical lipoma is an acceptable term for well-differentiated liposarcomas of the subcutis, it fails to convey the potentially life-threatening properties of retroperitoneal tumors. For these lesions as well as those in the deep soft tissues of the extremity, retention of the term well-differentiated liposarcoma is advocated.

Angiomatosis of soft tissue. An analysis of the histologic features and clinical outcome in 51 cases

The clinicopathologic features and clinical behavior of 51 cases of angiomatosis of soft tissue are analyzed. We have defined this lesion as a histologically benign vascular lesion that affects a large segment of the body in a contiguous fashion either by vertically involving multiple tissue types (e.g., subcutis, muscle, bone) or by involving similar tissue types (e.g., multiple muscles). Such lesions usually present in the first two decades of life and have a highly characteristic but not totally specific histologic pattern. The common pattern consists of a haphazard proliferation of vessels of varying sizes, particularly large veins. The latter have irregularly attenuated walls and intimal redundancies. However, the most distinctive feature is the presence of clusters of capillary vessels residing within or just adjacent to the vein walls. A second but uncommon pattern is that of clusters of capillary-sized vessels infiltrating the soft tissues. Both types are typically associated with large amounts of fat, suggesting that these lesions are more generalized mesenchymal proliferations rather than exclusive vascular lesions. This idea is supported by one unique case that included as part of the lesion a diffuse proliferation of glomus cells. Follow-up information in 25 cases (median 5 years; range 1-24) indicated that 22 patients experienced local recurrences. Nine patients developed more than one recurrence. There was no correlation between the age of onset of the lesion and the number of recurrences.(ABSTRACT TRUNCATED AT 250 WORDS)

Intraoral reconstruction with a microvascular peritoneal flap

The microvascular peritoneal flap offers a new reconstructive option for closure of intraoral defects. The flap is easy to raise, and donor-site morbidity is low. Unlike fascial flaps, in which the raw surface may take weeks to "mucosalize," the peritoneal surface heals primarily. Finally, the rectus muscle effectively covers all forms of mandibular reconstruction, and the reliable skin paddle makes possible the closure of substantial cutaneous defects.

Salvage of proximal humeral amputations with a remnant forearm flap

Spare-part surgery of upper extremity avulsions may facilitate primary soft-tissue healing and prosthetic rehabilitation. This procedure also may be applicable to the management of analogous proximal lower extremity avulsions where a short femoral stump and a shortage of soft tissue exist.

Cytotoxic therapy. Role of durable venous access

Aggressive chemotherapy regimens and supportive measures in haemato-oncology patients demand reliable venous access. Experience with this method in India has been limited. During a period of six months, we have used 42 subclavian indwelling catheters and 31 cubital Cavafix long lines. The mean age of patients in the two groups was 32 years and 7 years respectively. Subclavian catheters had a median duration of catheter placement of 46 days (range 4-145) and total 1494 catheter days, while cubital longlines yielded a median duration of insertion of 14 days (range 4-27) and total 508 catheter days. Catheter related complications were infection in 25% of patients, thrombophlebitis in 22%, blockade in 12% and misplacement in 17% in both groups taken together. The patients and families were extremely satisfied with the devices. Our experience supports further use of durable venous access in cancer patients. Implanted central venous catheters should be preferred whenever feasible.

Simultaneous reconstruction of cervical soft tissue and esophagus with a gastro-omental free flap

A microvascular transfer of gastric tube and omentum was used to simultaneously reconstruct cervical soft-tissue and esophageal defects in five patients. All patients had previous high-dose radiation and multiple flap reconstructions. The largest esophageal and soft-tissue defects were 10 cm and 160 cm2, respectively. All wounds healed primarily except for one orocutaneous fistula. There was one death from an intraoperative stroke. The gastro-omental flap is useful in cases where the reconstructive surgeon is faced with both esophageal and soft-tissue defects--particularly in heavily irradiated patients who have few reconstructive options.

Superoxide dismutase and catalase in skin flaps during venous occlusion and reperfusion

We studied the enzymatic concentrations of superoxide dismutase (SOD) and catalase (CAT) in rabbit abdominal island skin flaps during 8 and 10 hours of venous occlusion followed by 4 hours of reperfusion. A correlation between such enzyme activity at the end of ischemia and flap viability was tested. The results show that the accumulation of blood and blood-derived substances cause enzyme activity to increase considerably during venous occlusion. The amount of increase was similar for both 8- and 10-hour venous occlusion. "True tissue enzyme activity" (corrected for the contribution of blood and blood-derived substances) remained constant during venous occlusion, suggesting that the availability of scavenging enzyme does not correlate with ultimate flap viability. During early reperfusion, however, both SOD and CAT activity decreased, suggesting that membrane damage leads to an increase in membrane permeability and to the loss of intracellular enzymes.

A survey of microsurgery training in the United States

The increasing use of clinical and experimental microsurgical techniques has created a need for standardized, high-quality training programs in microsurgery. Toward this end, we conducted a study of the microsurgery instruction available in the United States. The data were collected from responses to surveys mailed to 55 microsurgery training centers across the country. Survey questions asked for a general characterization of each training program and its participants and for a specific description of course content. The results indicated that, even though training programs differed considerably, there were common elements. Total course length ranged from less than 40 hours to 80 hours, with a range of 32-40 hours devoted to basic microsurgery techniques. Forty percent of instructional programs were not certified for continuing medical education (CME) credit. Half of all reported trainees were residents in training. The basic microsurgery techniques common to most programs included instruction in microvascular end-to-end and end-to-side anastomoses of femoral arteries and veins in rats. Instruction in peripheral nerve repair was not offered. We conclude that, although there are merits to a diverse curriculum, it is time to institute a minimum level of standardized basic microsurgery training.

Free flap fricasse: iatrogenic thermal injury to a lateral arm flap

An iatrogenic thermal injury to a lateral-arm free tissue transfer is described. The thermal characteristics of the injurious agent are documented. Free tissue thermal conductivity and reparative potential are discussed.

Coverage of acute vascular injuries of the axilla and groin with transposition muscle flaps: case reports

Acute axillary or groin vascular injuries caused by farm machinery or shotgun blasts are often associated with extensive soft-tissue loss. Coverage of the repaired blood vessels with healthy tissue is necessary to avoid infection, desiccation, pseudoaneurysm, and rupture. Adjacent muscles are not always available to rotate for coverage, due to unacceptable functional loss, or injury to the principal vascular pedicle. We used proximally based trunk musculature with vascular pedicles out of the areas of injury to achieve coverage of four extensive axillary wounds and one extensive groin wound. Arterial repair only was performed in three axillary wounds. Combined arterial and venous repair were performed in one groin wound and one axillary wound. Followup ranging from 9 months to 5 years revealed no vascular failure or soft-tissue complications. We conclude that coverage of vascular repairs and soft-tissue defects with viable muscle is necessary in cases of extensive injury. Adjacent muscle is preferred for coverage, but when this is unavailable, coverage can still be achieved using more proximally pedicled muscles of the trunk.

Rotational muscle flaps: a new technique for covering infected vascular grafts

Twenty-one patients with established localized infection of vascular bypass grafts were treated with aggressive debridement and rotational muscle flap coverage to control graft infection. There were six gram-positive, six gram-negative, four mixed, and three fungal graft infections. Graft material included Dacron, Gore-Tex (registered trademark of W. L. Gore Associates Inc., Elkton, Md.), Dacron and Gore-Tex in combination, and saphenous vein. Twenty of 21 patients had successful preservation of graft function, local wound healing, and control of infection. There were no amputations or deaths. The one failure was caused by incomplete debridement of an infected graft segment. Aggressive debridement and rotational muscle flap coverage is an effective means of treating locally infected vascular bypass grafts.

Extravasation injury to the hand by intravenous phenytoin. Report of three cases

Extravasation of intravenous phenytoin can result in serious soft-tissue complications. Three patients are presented, one of whom lost a hand. Assessment of circulation and early decompression fasciotomies may be necessary in such cases. Caution is recommended in the intravenous administration of phenytoin. Infusions at rates of less than 50 mg/min and education of nursing staff about this potential complication will decrease its incidence.