A tribute to Emile Letournel, MD (1927-1994).
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Acetabulum↗
Biomedical subjects
E E Johnson
Publications and source records attributed to E E Johnson.
Psychosocial approach to medical practice.
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Education, Medical, Undergraduate↗
The use of the unreamed nail in tibial fractures with concomitant preoperative or intraoperative elevated compartment pressure or compartment syndrome.
Twelve patients with tibial shaft fractures and evidence of compartment syndrome or with documented elevated compartment pressures were treated with an unreamed locked intramedullary nail and a single-incision lateral four-compartment fasciotomy. There were six closed fractures and three grade I and three grade II open fractures. Ten fractures have achieved a solid union without shortening or significant angulation at an average follow-up of 8.1 months (range 4-26). Two patients were lost to follow-up. There were two delayed unions and one nonunion, all of which healed after additional treatment. Average time to tibial union was 5.8 months (range 2-24), with six fractures healing in < or = 4 months. One patient whose treatment was delayed > 12 h after his injury has a persistent neurologic deficit with a claw toe deformity. There were no superficial or deep infections. All patients obtained an excellent range of motion of the knee and ankle. Unreamed nailing of diaphyseal tibial fractures with an associated compartment syndrome provides optimal internal fixation while allowing excellent access for soft tissue care. We believe that the unreamed tibial nail, when combined with a single-incision, lateral, four-compartment fasciotomy, offers substantial advantage in the treatment of this injury, permitting optimal treatment of a difficult fracture and soft tissue injury.
Adult↗
Catheter based atrial defibrillation.
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Animals↗
Acute lengthening of shortened lower extremities after malunion or non-union of a fracture.
Forty-nine skeletally mature patients who had either a non-union or a malunion of a fracture of the tibia or the femur had correction of the deformity and acute axial lengthening of the fractured bone. Distraction was provided by the short AO/ASIF fracture distractor applied directly to the site of the osteotomy or non-union. At an average of sixty-three months (range, twenty-six to 105 months), the average increase in the tibial and femoral length was 1.7 and 3.2 centimeters, respectively. There were no compartment syndromes or ischemia secondary to any of the procedures. One patient had a transient sensory-nerve loss. Fatigue fractures were seen in two tibial plates, two femoral plates, and one femoral intramedullary nail used for osteosynthesis. A non-union developed after four other femoral intramedullary nailing procedures. One infection developed after lengthening of a tibia. Restoration of normal length by acute lengthening and internal fixation was achieved in twenty-seven patients. One patient had overlengthening of one centimeter. Fifteen patients had residual shortening of approximately one centimeter, three had shortening of more than one to 2.5 centimeters, and three patients had more than 2.5 centimeters of shortening. The patients in this series had acute restoration of limb length after traumatic shortening with a low prevalence of complications of neurovascular compromise. Three of the thirty tibial lengthenings and seven of the nineteen femoral lengthenings had to be followed by at least one additional procedure to obtain union.
Adult↗
True three dimensional stereographic display of 3D reconstructed CT scans of the pelvis and acetabulum.
Fractures of the acetabulum can cause the pelvis to shatter into a wide array of complex configurations which can be difficult to fully delineate preoperatively. In addition to plain radiography and standard computed tomography, technology now allows the reconstruction of magnetic resonance imaging (MRI) and computed tomography (CT) data into virtual objects; three dimensional (3D) representations of anatomy which exist only within the computer memory. Printouts and photographs of 3D reconstructions provide another level of anatomic information to the orthopaedic surgeon. However, current standard displays such as computer and video screens and photographic and radiographic film are all two dimensional (2D) modalities. Displaying 3D reconstructions in this standard 2D fashion, inescapably robs the images of up to one third of the information contained within them--all the true depth information which is the essence of 3D. Shading techniques and perspective have both been utilized to simulate depth, but true depth is still lacking. Recently, the authors have begun using a technique of computerized 3D reconstruction and recording which provides a true 3D display of the reconstructed images. The resultant gain in image realism is profound, somewhat similar to hearing full stereo audiophonic recording compared to monophonic, or to seeing in color rather than black and white. The image generation and display process is a computerized mathematical adaptation of the photographic technique of stereophotography. Once in place, the technique is relatively simple to use and can be achieved in several ways with a minimum of additional hardware. Potential benefits lie in the method's ability to convey, in one 3D display, the true 3D, spatial anatomic configuration of the imaged pelvis. The methods described are common to those forming the fundamental basis for virtual reality imaging. Current users of some 3D reconstruction systems can now easily generate images which can be viewed with all of the depth information restored, into a true 3D display.
Acetabulum↗
Delayed reconstruction of acetabular fractures 21-120 days following injury.
A retrospective review was performed of 207 patients treated by delayed reconstruction of acetabular fracture between 21 and 120 days following injury. Nineteen patients were lost to followup. One hundred eighty seven patients had 188 fractures classified as follows; 35 posterior wall, 9 posterior column, 5 anterior wall, 4 anterior column, 13 transverse, 49 transverse/posterior wall, 21 T shape, 8 posterior column/posterior wall, 8 anterior column posterior hemitransverse, and 34 both column fractures. The average preoperative delay was 43 days. Followup averaged 6.5 years (range, 9 months-30 years). Overall good to excellent results were achieved in 65% of patients, fair in 9%, and poor in 26%. Good to excellent results by fracture type were; posterior wall (51%), posterior column (89%), anterior wall (60%), anterior column (100%), transverse (69%), transverse/posterior wall (59%), T shape (62%), posterior column/posterior wall (88%), anterior column/posterior hemitransverse (75%), and both column (72%). Heterotopic ossification developed in 49 of 168 patients without prophylactic treatment, in 6 of 12 treated prophylactically with diphosphonate, and in 2 of 27 receiving prophylactic indomethacin therapy. There were 20 postoperative sciatic nerve palsies, 3 immediate and 5 delayed infections, 5 cases of pulmonary embolism, and 26 cases of avascular necrosis. Delayed management of acetabular fractures increases the difficulty of operative treatment and may result in a significant reduction in good to excellent results. Simple anterior or posterior wall fractures, associated transverse + posterior wall fractures, and T shape fractures have an increased risk of failure when treated within this time period.
Acetabulum↗
Surgical revision of malreduced acetabular fractures.
Early failure of open reduction and internal fixation of fractures of the acetabulum presents a treatment challenge even more difficult than that of the primary injury. This study evaluates the success of reoperation for 64 patients with surgical malreduction or secondary loss of reduction. In 36 patients (56%) the reconstruction achieved was within 2 mm of being anatomic as judged by plain radiography. Overall, 27 patients (42%) had excellent or good outcomes at an average 4.2 year followup. Delay to reoperation appeared to have an adverse affect on the result of surgery. At followup 57% of patients reoperated on within 3 weeks of injury were rated good or excellent. This figure dropped to 29% when the delay exceeded 12 weeks. These data do not compare favorably with results obtained in large series of singly operated fractures; however, they do indicate that it is possible to salvage a significant number of failed open reductions by reoperation.
Acetabulum↗
Heterotopic ossification prophylaxis following operative treatment of acetabular fracture.
Eighty seven patients with 88 fractures were retrospectively reviewed to assess the effect of postoperative prophylaxis on the formation of heterotopic ossification (HO). Sixty eight patients with 69 acetabular fractures were followed for an average of 21 months (range, 3-98 months). The grade of HO was assessed using the Brooker classification system. Thirty four fractures had no prophylactic treatment, 30 were treated prophylactically with indomethacin, two with radiation therapy, and three with both indomethacin and radiation. Twenty (59%) of 34 untreated fractures developed HO, of which nine (26%) were Grade III or IV. Thirteen (43%) of 30 fractures treated with indomethacin developed HO, of which 5 (16%) were Grade III and none were Grade IV. Twenty one of 24 fractures were stabilized through the extended iliofemoral approach; 13 of these had no prophylaxis. Eleven of the 13 developed HO; eight were Grade III or IV (62%). Seven of eight fractures treated with indomethacin following the extended iliofemoral approach developed HO; one was Grade III (13%) and non Grade IV. There was no significant difference between 13 patients who were not treated prophylactically and 18 indomethacin treated patients stabilized through the Kocher-Langenbeck approach. Only one of 11 patients had HO (Grade I) following an ilioinguinal approach. Postoperative radiation therapy, with or without indomethacin, resulted in three patients with Grade 0 HO (all radiated 1-4 days post surgery), one with Grade II (radiated postoperative Day 8), and one with Grade III HO (significant delay in surgery with preoperative Grade III HO of the hip).(ABSTRACT TRUNCATED AT 250 WORDS)
Acetabulum↗
Genomic structure and chromosomal localization of the human deoxycytidine kinase gene.
Deoxycytidine kinase (NTP:deoxycytidine 5'-phosphotransferase, EC 2.7.1.74) is an enzyme that catalyzes phosphorylation of deoxyribonucleosides and a number of nucleoside analogs that are important in antiviral and cancer chemotherapy. Deficiency of this enzyme activity is associated with resistance to these agents, whereas increased enzyme activity is associated with increased activation of such compounds to cytotoxic nucleoside triphosphate derivatives. To characterize the regulation of expression of this gene, we have isolated genomic clones encompassing its entire coding and 5' flanking regions and delineated all the exon/intron boundaries. The gene extends over more than 34 kilobases on chromosome 4 and the coding region is composed of 7 exons ranging in size from 90 to 1544 base pairs (bp). The 5' flanking region is highly G+C-rich and contains four regions that are potential Sp1 binding sites. A 697-bp fragment encompassing 386 bp of 5' upstream region, the 250-bp first exon, and 61 bp of the first intron was demonstrated to promote chloramphenicol acetyltransferase activity in a T-lymphoblast cell line and to have > 6-fold greater activity in a Jurkat T-lymphoblast than in a Raji B-lymphoblast cell line. Our data suggest that these 5' sequences may contain elements that are important for the tissue-specific differences in deoxycytidine kinase expression.
Base Sequence↗
Regulation of human deoxycytidine kinase expression.
The human deoxycytidine kinase gene is a single copy gene and is comprised of seven exons that are spread over more than 34 kb of the genome. The 5'-flanking region is highly G/C rich and does not contain CAAT or TATA boxes. This region, when cloned into a recorder gene construct containing the chloramphenicol acetyltransferase gene, is capable of mediating CAT activity in human lymphoid cell lines and appears to have greater activity in human T, as compared to B, lymphoblast cell lines. The expression of the gene at the mRNA level does not appear to be cell-cycle regulated in that the levels of mRNA in human peripheral blood T lymphocytes remain constant as the cells progress from a resting to a proliferating state. Since this enzyme catalyzes the conversion of a number of chemotherapeutic agents to their corresponding monophosphate form and is thus essential for their activation, it will be important to define further the genetic elements which regulate the expression of this gene.
Cell Division↗
Synovial metallosis resulting from intraarticular intramedullary nailing of a distal femoral nonunion.
An 80-year-old man sustained a T-shaped supracondylar fracture of the femur associated with distal one-third shaft comminution. Initial failure of a 95 degrees angle blade plate was followed by insertion of an intraarticular intramedullary nail stabilized with static locking-screw fixation. A second failure of the implant was treated by extraarticular tension band condylar buttress plate osteosynthesis. Severe knee synovial metallosis was found at the time of removal of the intraarticular nail device.
Aged↗
Estimating the 95% effective defibrillation dose.
Minimum squared error (MinSE) testing protocols and a MinSE estimator are presented which accurately estimate the voltage that defibrillates 95% of the time (the ED95). The MinSE experimental procedures, presented in the form of lookup tables, detail the response to successful and unsuccessful trials. The lookup tables also show the ED95 estimates calculated from the observed results using the MinSE estimator. Two assumptions are required to develop the look-up tables: 1) the dose-response curve, chosen using a statistical analysis of a retrospective sample, and 2) the distribution of the ED95's in the population. The MinSE estimator and experimental procedure are examined in a prospective study of five dogs (19-25 kg, heart weights 139.3-236.9 gm) using nonthoracotomy implantable defibrillator electrodes and a biphasic defibrillation waveform (3.5 ms first phase, 2.0 ms second phase). Employing an ED95 population distribution assumption applicable to most implantable defibrillator electrodes and waveforms, e.g., the ED95 is between 0.0 and 800.0 V, the measured rms error was 15% of the mean measured ED95 for the MinSE, four test shock, ED95 estimates. If the protocols are designed with an ED95 population distribution assumption for animals of the same species and size, and defibrillation is constrained to one electrode configuration and waveform, the estimates improve by 3.8%. Using techniques from the Bayesian statistics literature, the MinSE approach can be extended to a variety of defibrillation parameter estimation problems.
Algorithms↗
Efficient electrode spacing for examining spatial organization during ventricular fibrillation.
Spatial organization has been observed during episodes of ventricular fibrillation (VF) by recording epicardial unipolar electrograms on a grid of electrodes. In such studies, the choice of spacing between electrodes is an important decision, affecting the resolution and the size of the domain to be studied. A basic tenet of sampling theory, the Nyquist criterion, states that an electrode spacing smaller than half the smallest significant wavelength is required to capture the important details of a spatially sampled process. In this paper, we suggest a method to choose a practical interelectrode spacing by examining wavenumber power spectra of high-resolution VF data recorded from a square 11 x 11 array of electrodes spaced 0.28 mm apart. The plaque was sutured on the epicardium near the left ventricular apex in seven anesthetized pigs. VF was induced with ac simulation. Unipolar extracellular electrograms were simultaneously recorded from each channel for 2 s after the induction of VF. Each signal was sampled in time at 1000 Hz. Wavenumber power spectra were calculated for 100 ms segments using the zero-delay wavenumber spectrum method, for a total of 140 power spectra. All spectra had dominant peaks at the origin and fell off rapidly with increasing wavenumber (decreasing wavelength). In all the spectra, every wavelength shorter than 1.4 mm contributed insignificant power. Furthermore, in 134 of 140 spectra (96%), insignificant power levels were associated with every wavelength shorter than 2.8 mm. These results suggest that, for unipolar extracellular electrodes, an intersensor spacing on the order of 1 mm is appropriate to study organization during early VF.
Animals↗
A quantitative measurement of spatial order in ventricular fibrillation.
INTRODUCTION: The degree of organization in ventricular fibrillation (VF) is not known. As an objective measurement of spatial order, spatial correlation functions and their characteristic lengths were estimated from epicardial electrograms of pigs in VF. METHODS AND RESULTS: VF was induced by premature stimulation in five pigs. Electrograms were simultaneously recorded with a 22 x 23 array of unipolar electrodes spaced 1.12 mm apart. Data were obtained by sampling the signals at 2000 Hz for 20 minutes immediately after the initiation of FV. Correlations between all pairs of signals were computed at various times. Correlation lengths were estimated from the decay of average correlation as a function of electrode separation. The correlation length of the VF in pigs was found to be approximately 4 to 10 mm, varying as fibrillation progressed. The degree of correlation decreased in the first 4 seconds after fibrillation then increased over the next minute. CONCLUSION: The correlation length is much smaller than the scale of the heart, suggesting that many independent regions of activity exist on the epicardium at any one time. On the other hand, the correlation length is 4 to 10 times the interelectrode spacing, indicating that some coherence is present. These results imply that the heart behaves during VF as a high dimensional, but not random, system involving many spatial degrees of freedom, which may explain the lack of convergence of fractal dimension estimates reported in the literature. Changes in the correlation length also suggest that VF reorganizes slightly in the first minute after an initial breakdown in structure.
Animals↗
Ipecac myopathy and cardiomyopathy.
Two cases of ipecac myopathy, one with associated cardiomyopathy are reported. Both patients were young women with eating disorders who came to medical attention because of diffuse muscle weakness. Clinical and electromyographic data suggested ipecac myopathy and muscle biopsies confirmed this diagnosis. One patient had associated clinical and echocardiographic evidence of significant cardiomyopathy. The myopathy resolved and the echocardiogram returned to normal after discontinuing the use of ipecac.
Adult↗
Using a conceptual model for practice in a nursing wellness centre for seniors.
The use of a conceptual model to guide practice is critical to the maturation of the profession. Distinguishing between nursing and other health care professions rests, in part, on nursing's ability to articulate what it offers to clients. The nursing paradigm, comprising the essential components of the individual (client), health, environment, and nursing, provides general rules of thumb for the profession (Fawcett, 1984). Selecting a nursing model for a practice setting contributes to theory development: clinical questions generated from the model can be formulated as testable hypotheses. The Wellness Centre offers a unique opportunity for use of a conceptual model in a nurse-managed practice setting serving seniors. If conceptual models are to be useful, they need to be tested in the settings where nurses practise and for the roles that comprise nursing. Use of the crisis model, in this setting provides reality testing of the model which has evolved to a higher level of internal consistency and external validity as a direct result of practice.
Aged↗
Avulsion fracture of the coracoid associated with acromioclavicular dislocation.
A case report of an avulsion fracture of the coracoid process associated with a type III acromioclavicular dislocation is presented. The mechanism of injury and results of treatment in eighteen previously reported cases in the English-language literature are reviewed. Both operative and nonoperative treatment appear to offer equally favorable results. The treatment of this rare combined injury may follow the same guidelines used for treating isolated type III acromioclavicular dislocations.
Acromioclavicular Joint↗