Determination of the Avogadro constant by counting the atoms in a 28Si crystal.

The Avogadro constant links the atomic and the macroscopic properties of matter. Since the molar Planck constant is well known via the measurement of the Rydberg constant, it is also closely related to the Planck constant. In addition, its accurate determination is of paramount importance for a definition of the kilogram in terms of a fundamental constant. We describe a new approach for its determination by counting the atoms in 1 kg single-crystal spheres, which are highly enriched with the 28Si isotope. It enabled isotope dilution mass spectroscopy to determine the molar mass of the silicon crystal with unprecedented accuracy. The value obtained, NA = 6.022,140,78(18) × 10(23) mol(-1), is the most accurate input datum for a new definition of the kilogram.

Craniofacial distraction osteogenesis: a review of 3278 cases.

The nascent field of craniofacial distraction osteogenesis has not yet been subjected to a rigorous evaluation of techniques and outcomes. Consequently, many of the standard approaches to distraction have been borrowed from the experience with long bones in orthopedic surgery. The ideal "latency period" of neutral fixation, rate and rhythm of distraction, and consolidation period have not yet been determined for the human facial skeleton. In addition, because the individual craniofacial surgeon's experience with distraction has generally been small, outcomes and meaningful complication rates have not yet been published. In this study, a four-page questionnaire was sent to 2476 craniofacial and oral/maxillofacial surgeons throughout the world, asking about their experiences with distraction osteogenesis. Information about the types of cases, indications for surgery, surgical techniques, postoperative management, outcomes, and complications were tabulated. Of 274 respondents (response rate, 11.4 percent), 148 indicated that they used distraction in their surgical practice. One hundred forty-five completed surveys were entered into a database that provided information about 3278 craniofacial distraction cases. Statistical analyses were performed comparing the rates of premature consolidation, fibrous nonunion, and nerve injury, on the basis of the use of a latency period and different rates and rhythms of distraction. In addition, the rates of all complications were determined and compared on the basis of the number of distraction cases performed per surgeon. The results of the study clearly show a wide variation in the surgical practice of craniofacial distraction osteogenesis. Although the cumulative complication rate was found to be 35.6 percent, there is a pronounced learning curve, with far fewer complications occurring among more experienced surgeons (p < 0.001). The presence of inferior alveolar nerve injury as a result of mandibular distraction was much lower for respondents whose distraction regimens consisted of no more than 1 mm of distraction per day (19.5 percent versus 2.4 percent; p < 0.001). No evidence was found to support the use of a latency period or to divide the daily distraction regimen into more than one session per day. Conclusions could not be drawn from this study regarding the length of the consolidation period. Overall, the surgeon-reported outcomes are comparable with those published for other craniofacial procedures, despite the higher incidence of complications. Although conclusions made on the basis of a subjective questionnaire need to be interpreted cautiously, this study has strength in the large numbers of cases reviewed. Because of the anonymity of responses, it has been assumed that surgeons who responded to the survey reported accurate numbers of complications and successful outcomes. Finally, additional clinical and animal studies that will be of benefit in advancing the field of craniofacial distraction osteogenesis are outlined.

Management strategies for pyoderma gangrenosum: case studies and review of literature.

Pyoderma gangrenosum (PG) is a systemic disease with cutaneous manifestations consisting of necrotizing ulceration. The etiology of PG is controversial, and optimal management strategies have not been established. Current management is primarily medical to control the systemic inflammatory process, with occasional surgical intervention at the ulcer site. Based on the current literature and on the authors' clinical experience, the optimal outcome depends on early diagnoses and a combination of medical and surgical therapy. Initial management is directed toward medical control of the inflammatory process and local wound care. Surgical strategies involve recipient site preparation via local wound care and serial allograft followed by autologous skin graft or muscle flap coverage when necessary. Long-term wound stabilization is obtained only through control of the systemic and local inflammatory process.

Long-term physical impairment and functional outcomes after complex facial fractures.

To develop an understanding of the expected functional outcomes after facial trauma, a retrospective cohort study of patients with complex facial fractures was conducted. A cohort of adults aged 18 to 55 years who were admitted to the R. Adams Cowley Shock Trauma Center between July of 1986 and July of 1994 for treatment of a Le Fort midface fracture (resulting from blunt force) was retrospectively identified. Outcomes of interest included measures of general health status and psychosocial well being in addition to self-reported somatic symptoms. General health status was ascertained using the Medical Outcomes Study 36-Item Short Form Health Survey (SF-36). The Body Satisfaction Scale was used to define patient concerns about altered body image and shape. To determine whether complex maxillofacial trauma and facial fractures contributed to altered social interactions, the Social Avoidance and Distress scale was used. In addition, information about a patient, his or her injury, and its treatment were ascertained from the medical records. Using the methods described above, 265 patients with Le Fort fractures were identified. These individuals were matched to a similar group of 242 general injury patients. A total of 190 of the Le Fort patients (72 percent of those eligible for the study) and 144 (60 percent) general injury patients were successfully located, and long-term interview data were acquired.Le Fort fracture patients as a group had similar health status outcomes when compared with the group of general injury patients. However, when outcomes were examined by the complexity of the Le Fort fracture, the authors found that study subjects with severe, comminuted Le Fort injuries (group D) had significantly lower SF-36 scores (worse outcomes) for the two dimensions related to role limitations: role limitations due to physical problems and role limitations due to emotional problems (p < 0.05). SF-36 scores for all other dimensions except physical function were also lower for comminuted versus less complex Le Fort fractures, although differences were not statistically significant.Specifically, there was a direct relationship between severity of facial injury and patients reporting work disability. Of group C and D Le Fort patients (severely comminuted fractures) only 55 and 58 percent, respectively, had returned to work at the time of follow-up interview. These figures are significantly lower than the back-to-work percentage of patients with less severe facial injury (70 percent). When study participants were asked if they were experiencing specific somatic symptoms at the time of the interview that they had not experienced before the injury, a significantly larger percent of the Le Fort fracture patients (compared with the general injury patients) responded in the affirmative. Differences between the Le Fort fracture and general injury groups were statistically significant (p < 0.05) for all 11 symptoms. The percentage of patients reporting complaints increased with increasing complexity of facial fracture in the areas of visual problems, alterations in smell, difficulty with mastication, difficulty with breathing, and epiphora, and these differences reached statistical significance. Patients sustaining comminuted Le Fort facial fractures report poorer health outcomes than patients with less severe facial injury and substantially worse outcomes than population norms. It is also this severely injured population that reports the greatest percentage of injury-related disability, preventing employment at long-term follow-up. The long-term goal of centralized tertiary trauma treatment centers must be to return the patient to a productive, active lifestyle.

Traumatic optic neuropathy: a review of 61 patients.

The outcome of traumatic optic neuropathy was evaluated following penetrating and blunt injuries to assess the effect of treatment options, including high-dose steroids, surgical intervention, and observation alone. Factors that affected improvement in visual acuity were identified and quantified. Sixty-one consecutive, nonrandomized patients presenting with visual loss after facial trauma between 1984 and 1996 were assessed for outcome. Pretreatment and posttreatment visual acuities were compared using a standard ophthalmologic conversion from the values of no light perception, light perception, hand motion, finger counting, and 20/800 down to 20/15 to a logarithm of the minimum angle of resolution (log MAR). The percentage of patients showing visual improvement and the degree of improvement were calculated for each patient group and treatment method. Measurements of visual acuity are in log MAR units +/- standard error of the mean. Patients who sustained penetrating facial trauma (n = 21) had worse outcomes than patients with blunt trauma (n = 40). Improvement in visual acuity after treatment was seen in 19 percent of patients with penetrating trauma compared with 45 percent of patients with blunt trauma (p < 0.05). Furthermore, patients with penetrating trauma improved less than those with blunt trauma, with a mean improvement of 0.4 +/- 0.23 log MAR compared with 1.1 +/- 0.24 in blunt-trauma patients (p = 0.03). The patients with blunt trauma underwent further study. There was no significant difference in improvement of visual acuity in patients treated with surgical versus nonsurgical methods; however, 83 percent of patients without orbital fractures had improvement compared with 38 percent of patients with orbital fractures (p < 0.05). The mean improvement in patients without orbital fractures was 1.8 +/- 0.65 log MAR compared with 0.95 +/- 0.26 in patients with orbital fractures (p = 0.1). Twenty-seven percent of patients who had no light perception on presentation experienced improvement in visual acuity after treatment compared with 100 percent of patients who had light perception on admission (p < 0.05). The mean improvement in patients who were initially without light perception was 0.85 +/- 0.29 log MAR compared with 1.77 +/- 0.35 in patients who had light perception (p < 0.05). There were no significant differences in improvement of visual acuity when analyzing the effect of patient age and timing of surgery. Patients who sustain penetrating trauma have a worse prognosis than those with blunt trauma. The presence of no light perception and an orbital fracture are poor prognostic factors in visual loss following blunt facial trauma. It seems that clinical judgment on indication and timing of surgery, and not absolute criteria, should be used in the management of traumatic optic neuropathy.

Cheek reconstruction with laterally based flaps.

Laterally based cervicofacial advancement flaps that follow the borders of facial aesthetic subunits provide a more aesthetic solution to the reconstruction of anterior cheek defects than do standard cervicofacial flaps or skin grafts. The circulation in these laterally and inferiorly based flaps is improved, because the transverse facial artery is spared. These flaps also provide better contour and possess more aesthetic scar placement than do anteriorly and inferiorly based flaps.

Utility of the lateral arm flap in head and neck reconstruction.

Soft-tissue defects of the head and neck are often reconstructed with fasciocutaneous free flaps. The radial forearm flap is used most commonly, however the lateral arm flap may be the flap of choice in certain situations. Advantages include flap elevation with simultaneous tumor ablation, avoidance of intraoperative patient position changes, and primary closure of the donor site. After extirpative procedures of the head and neck region, 4 patients were reconstructed with the lateral arm flap. Flap survival was 100%, a vein graft to supplement the short pedicle length was necessary in 1 patient, all donor sites were closed primarily, and secondary procedures to reduce flap bulk were necessary in 2 patients. The lateral arm flap is an excellent alternative to the radial forearm flap and should be included in the armamentarium of the reconstructive head and neck surgeon.

Improved mandible function after hemimandibulectomy, condylar head preservation, and vascularized fibular reconstruction.

Temporomandibular joint dysfunction after tumor extirpation of the hemimandible is a frequent sequela after condylar head reconstruction. Condylar head resection is often performed because of oncological and vascular considerations. Recent studies have demonstrated that malignancies of the mandibular ramus and body rarely involve the condylar head, and that the vascularity and supportive structures of the condylar head are sufficient to maintain viability and function. This study demonstrates that temporomandibular joint function is preserved after hemimandibulectomy without resection of the condylar head. Fixation of a vascularized fibular flap to the condylar head is performed in situ. Condylar viability and growth is maintained with painless incisal opening. The condylar head is a growth center for the mandible in the pediatric population. Its preservation in these patients will avoid the long-term problems associated with growth center loss such as malocclusion and concomitant maxillary deformity.

Methods and results of rhinophyma treatment.

Rhinophyma is a disfiguring soft-tissue hypertrophy of the nose. It is an uncommon disease that primarily affects Caucasian men in the fifth to seventh decades of life. Nine cases from the authors' series and a comparison of results following various treatment modalities are presented. Eight of the patients were Caucasian and one was African American. Excision of the diseased tissue with a scalpel or Goulian dermatome using loupe magnification provided the safest means of preserving the underlying sebaceous gland fundi that permit spontaneous re-epithelialization with the least scarring.

Multiple-component tissue reconstruction of a complex dorsal foot wound through a single gracilis muscle donor incision.

The authors describe the ability of the gracilis muscle to provide multiple tissue components- skin, muscle, nerve, and tendonin the reconstruction of a complex dorsal foot wound resulting from a sarcoma resection. The deficits of skin, deep peroneal nerve, anterior tibialis tendon, and dorsal extensor retinaculum were all reconstructed with the gracilis component flap through one medial thigh incision. This case illustrates two important points: (1) the gracilis flap is tremendously versatile and can serve as the donor for multiple tissue components in complex reconstructions, and (2) donor site morbidity can and should be minimized even in complex reconstructions.

Prefabrication of combined composite (chimeric) flaps in rats.

The purpose of this study was to prefabricate a new combined composite (chimeric) flap that consists of four different tissues. The tissues were prefabricated around two independent pedicles that ultimately join as a single main pedicle. In the inguinal area of 36 rats, the saphenous and the superficial inferior epigastric (SIE) pedicles were dissected and prepared as vascular carriers. A fascial graft and a local muscle flap were wrapped around the saphenous pedicle. The SIE pedicle was then implanted under the abdominal skin to supply a future skin flap. An ear cartilage graft was also inserted under the abdominal skin and adjacent to the implanted SIE pedicle. After allowing 2-, 4-, 6-, and 12-week prefabrication periods in different groups of nine animals, the prefabricated tissues were raised around two pedicles nourished by the femoral pedicle and then transferred. Flap survival was assessed by observation, microangiography and histology. The skin flaps showed survival rates of 52 +/- 17% (mean +/- standard error of the mean), 64 +/- 16%, 86 +/- 11%, and 100 +/- 0% of the total areas in the 2-, 4-, 6-, and 12-week prefabricated flaps respectively. None of the control grafts that were prepared on the contralateral side survived totally. A significant difference was found between the 12- and 2-week (p < 0.008), 12- and 4-week (p < 0.02), and 6- and 2-week (p < 0.05) prefabrication groups. Histologically, fascial and cartilage grafts, and portions of muscle were viable in the 2- and 4-week groups. Also, noticeable necrosis was found in the skin flaps in these groups. The muscle showed mild (at 2, 4, and 6 weeks) and moderate (at 12 weeks) atrophy. After prefabrication for 6 weeks, all tissues demonstrated good survival. This study shows that a combined composite flap can be prefabricated successfully in rats after a 6-week period of prefabrication.

Recurrent ventral herniation in Ehlers-Danlos syndrome.

Ehlers-Danlos syndrome is an inherited collagen disorder characterized by skin hyperextensibility, joint laxity, and tissue friability. In this study, it was hypothesized that Ehlers-Danlos syndrome is frequently undiagnosed in patients who present for repair of ventral abdominal wall hernias. A retrospective chart review was conducted, and patients who had presented for elective repair of recurrent abdominal wall herniation were identified. In all patients, one or more prior attempts at repair with either mesh or autologous tissues had failed. Patients in whom abdominal wall components were lost secondary to extirpation or trauma, patients who had required acute closure, and patients with less than 2 months of follow-up were excluded. Twenty patients met these criteria. Twenty cases of recurrent ventral hernia repairs were reviewed, with special attention to identification of the preoperative diagnosis of Ehlers-Danlos syndrome. Patients ranged in age from 29 to 75 years, with a mean age of 54 years. Five patients were male (25 percent), and 15 were female (75 percent). The majority (95 percent) were Caucasian. The most common initial procedures were gynecologic in origin (35 percent). A precise closure technique that minimizes recurrence after ventral hernia repairs was used. With use of this technique, there was only one recurrence over a follow-up period that ranged from 2 to 60 months (mean follow-up duration, 25.7 months). Two patients with Ehlers-Danlos syndrome were identified, and their cases are presented in this article. The "components separation" technique with primary component approximation and mesh overlay was used for defect closure in the two cases presented. The identification of these two patients suggests the possibility of underdiagnosis of Ehlers-Danlos syndrome among patients who undergo repeated ventral hernia repair and who have had previous adverse postoperative outcomes. There are no previous reports in the literature that address recurrent ventral abdominal herniation in patients with Ehlers-Danlos syndrome.

Converting to digital photography: a model for a large group or academic practice.

Digital photography has become an economical and efficient substitute for conventional photography. We recently converted our resident clinical photography to a digital format to make archiving more efficient and to save the costs of clinical photography. We present a model that can be applied to a large group or academic practice outlining the conversion of our clinical photography to digital format. We discuss the costs that we have incurred during the past 3 years of conventional photography, the economic benefit and costs for conversion to digital, and a 5-year projection of savings using digital photography. We also discuss the advantages of digital photography and the equipment needed for the conversion.

Correction of frontal bone hypertrophy with setback osteotomy and hydroxyapatite cement.

This case report illustrates a method of correction for severe hypertrophy of the frontal bone. Accurate preoperative assessment including physical examination, photographs, and radiological studies are necessary. The anterior table of the frontal bone is removed, recontoured, and stabilized to the adjacent bone while maintaining the integrity of the frontal sinus mucosa. Hydroxyapatite cement is used to resurface and contour the frontal bone. This method is demonstrated to be safe and well tolerated, and should be considered as the procedure of choice for this condition.

What have we learned about traumatic diaphragmatic hernias in children?

BACKGROUND/PURPOSE: Diaphragmatic injuries have been reported to be a predictor of serious associated injuries in trauma and a marker of severity. The aim of this retrospective study was to identify pitfalls in the diagnosis and treatment of these injuries in children. METHODS: Data were collected from all patients admitted to the trauma service with traumatic diaphragmatic hernias for the period of January 1977 to August 1998. The authors evaluated 15 cases of traumatic diaphragmatic rupture (6 girls and 9 boys). RESULTS: Mean age was 7.5 years (range, 3 weeks to 15 years). Thirteen patients suffered from blunt trauma, and 2 patients suffered from penetrating trauma. The right and left hemidiaphragms were injured equally (7 patients each), with 1 additional patient suffering from bilateral injuries. All but 1 patient had laparotomies for trauma (n = 14). The diagnosis was made preoperatively in 8 patients (53%) with just a chest radiograph. Computed tomography (CT) scan, magnetic resonance imaging (MRI), and oral contrast studies were used as ancillary tests to diagnose traumatic diaphragmatic rupture. There were 3 missed injuries. Associated injuries included liver lacerations (47%), pelvic fractures (47%), major vessels tear (40%), bowel perforations (33%), long bone fractures (20%), renal lacerations (20%), splenic lacerations (13%), and closed head injuries (13%). The mean hospital stay was 20 days (range, 7 to 60 days). Complications were observed most commonly in those patients with multiple injuries and included postoperative ileus (40%), pneumonia (30%), pancreatitis (20%), wound infection (20%), intestinal obstruction (20%), cholestasis (10%), and renal failure (6%). Five deaths (33%) were caused by hemorrhagic shock, respiratory failure, coagulopathy, and refractory acidosis. CONCLUSIONS: Traumatic diaphragmatic hernias usually are associated with serious injuries in children. It is important to combine a high index of suspicion with radiological diagnostic tests in patients at risk. Palpation and/or visualization of both diaphragms at laparotomy is extremely important in detecting these injuries when they are not suspected preoperatively.

Medial pedicle reduction mammaplasty for severe mammary hypertrophy.

Current options in reduction mammaplasty for severe mammary hypertrophy include amputation with free-nipple graft as well as the inferior pedicle and bipedicle techniques. Complications of these procedures include nipple-areola necrosis, insensitivity, and hypopigmentation. The purpose of this study was to determine whether medial pedicle reduction mammaplasty can minimize these complications. Twenty-three patients with severe mammary hypertrophy were studied. The medial pedicle successfully transposed the nipple-areola complex in 44 of 45 breasts (98 percent). Mean change in nipple position was 17.1 cm, and mean weight of tissue removed was 1604 g per breast. Nipple-areola sensation was retained in 43 of 44 breasts (98 percent) using a medial pedicle. Hypopigmentation was not observed, and central breast projection was restored in all patients. This study has demonstrated that medial pedicle reduction mammaplasty is a safe and reliable technique and should be given primary consideration in cases of severe mammary hypertrophy.

Surgeon perspectives on surgical options for early-stage breast cancer.

To evaluate the practice patterns of general and plastic surgeons regarding patients with early-stage breast cancer, all general and plastic surgeons in Quebec and Maryland were mailed self-administered questionnaires evaluating surgeon demographics, practice patterns, treatment preferences, and satisfaction with the results of lumpectomy and radiation therapy or breast reconstruction. Response rates of 38.3 percent and 26.7 percent were obtained for general surgeons in Quebec and Maryland, respectively. The ratio of reported mastectomies to lumpectomies was 1:2 in Maryland and 1:5 in Quebec. All general surgeons considered lumpectomy an important option. Ninety percent of Maryland surgeons versus 44 percent of Quebec surgeons considered mastectomy important. A total of 53.6 percent versus 24.9 percent of general surgeons in Maryland and Quebec, respectively, considered delayed reconstruction an important option. Additionally, 81.3 percent of Maryland surgeons considered immediate reconstruction important, and 79.6 percent discussed it with all stage I or II patients. More than 75 percent of Quebec general surgeons reported discussing immediate or delayed reconstruction with < or =50 percent of these women. Response rates of 53.6 percent and 48.8 percent were obtained for plastic surgeons in Quebec and Maryland, respectively. In one year Quebec plastic surgeons reported that they performed less than half the number of reconstructions performed by Maryland plastic surgeons (7.2 versus 17.3). In Quebec, 82.3 percent of surgeons reported that they frequently discuss delayed reconstruction, 25.1 percent immediate, 62.5 percent pedicled TRAM, and 51.7 percent nonautogenous options. In Maryland, 74.3 percent of plastic surgeons frequently discuss delayed reconstruction, 95.7 percent immediate, 89.9 percent pedicled TRAM, and 85.9 percent nonautogenous options. For women with early-stage breast cancer, regional variations exist in the surgical options discussed and provided.

Surgical options for the early-stage breast cancer: factors associated with patient choice and postoperative quality of life.

Patients with early-stage breast cancer have three surgical options: lumpectomy with radiotherapy, mastectomy alone, and mastectomy with breast reconstruction. Our objective was to compare women in these three groups with respect to demographics, preoperative counseling, postoperative body image, and quality of life. Women having undergone surgery for stage 1 or 2 breast cancer between 1990 and 1995 were selected by random sampling of hospital tumor registries and were mailed a self-administered questionnaire, which included the Medical Outcomes Survey Short Form 36. Patients were stratified into three mutually exclusive groups: lumpectomy with axillary node dissection and radiotherapy, modified radical mastectomy, and modified radical mastectomy with breast reconstruction. In total, 267 of 525 surveys were returned (50.9 percent). Compared with mastectomy patients, breast reconstruction patients were younger (p < 0.001), better educated (p = 0.001), and more likely Caucasian (p = 0.02). Among mastectomy patients, 54.9 percent recalled that lumpectomy had been discussed preoperatively and 39.7 percent recalled discussion of breast reconstruction. Post-operative comfort with appearance was significantly lower for mastectomy patients. The relationship between type of surgery and postoperative quality of life varied with age. Under 55, quality of life was lowest for mastectomy patients on all but two Medical Outcomes Survey Short Form 36 subscales. Over 55, quality of life was lowest for lumpectomy patients on all subscales (p < 0.05 for all subscales except social functioning and role-emotional). Treatment choice may be related to age, race, education, and preoperative counseling. Whereas the effect of breast cancer on a woman's life is complex and individual, the type of surgery performed is a significant variable, whose impact may be related to patient age.