Lattice parameters as revealed by electron microscopy and a comparison between lipoprotein crystals from cyclostome eggs formed in vivo and in vitro.

Electron diffraction of in vitro-grown lipoprotein crystals from cyclostome eggs (Ichthyomyzon unicuspis) has revealed lattice parameters (a = 19.4 nm, b = 8.9 nm, c = 8.9 nm, beta = 103.4 degrees; apparent symmetry C2 at 3 nm resolution) that were very close to those determined by X-ray diffraction in the same specimen and to others determined by the same electron microscope method in five cyclostome species (in-vivo crystals). Electron imaging has shown all investigated lipoprotein crystals to present similar views projected down the principal crystal axes. Electron diffraction of embedded and heavy-metal-treated lipoprotein crystals is a rapid procedure and a useful low-angle extension to X-ray diffraction.

Distribution of molecule numbers per secretion granule. A study of crystals in glucagon secreting cells.

The occurrence of a crystalline component in secretion granules of teleost A-cells (islets of Langerhans) has been used to derive, in Xi-phophorus helleri, the size distribution of secretion granules in terms of (glucagon) molecule numbers. The distribution is asymmetric with the arithmetical mean = 7.1 x 10(5), the median Q0.5 = 4.7 x 10(5), and the range from 8.5 x 10(4) to 4.5 x 10(6) molecules, as determined in a sample of 203 crystals from 9 specimens. This result is based on the following assumptions: The crystals are rhombic dodecahedra with a greater than 4.2 nm and space group P213, thus much resembling cubic porcine glucagon; they are teleost glucagon and contain the whole glucagon content of the granule. If the latter assumptions are rejected, the above molecule numbers become minimum numbers of protein molecules. A change to other space groups also compatible with the diffraction patterns observed would only double the above values. The values are compared with corresponding ones from other species and also from other types of endocrine cells and errors are discussed.

Correlative radiographic, scintigraphic, and histological evaluation of exostoses.

We reviewed the cases of twenty-four patients with solitary or multiple exostoses to correlate their radiographic, scintigraphic, and histological evaluations. We studied twenty-five excised lesions, two of them exostotic chondrosarcomas, from twenty-two patients. There were two patterns of bone-scan activity and there was a direct correlation between enchondral bone formation and radionuclide uptake in all patients, both skeletally immature and mature. So-called quiescent lesions--those with inactive scans--were those that lacked histological evidence of enchondral bone formation. Those with increased uptake--active exostoses--all demonstrated active formation of enchondral bone. Evidence of active exostotic growth could be demonstrated on bone scans well beyond the time of skeletal maturity. The bone scan did not qualitatively differentiate the benign active exostoses from the two lesions with malignant degeneration. Increased uptake related to enchondral bone formation was a feature of both. An inactive scan, however, seemed to exclude the possibility of malignant degeneration in the exostosis.

Results of knee manipulations after anterior cruciate ligament reconstructions.

We analyzed the results of knee manipulations in 42 knees that had persistent flexion or extension deficits after intraarticular ACL reconstructions. All manipulations were done under a spinal or general anesthetic and, in 10 cases, arthroscopic debridement of adhesions also was performed. The average time from reconstruction to manipulation was 7 months (range, 3 to 14 months) and the average followup was 26 months (range, 6 to 56 months). At manipulation, average flexion was increased from 95 degrees to 136 degrees and average extension from 11 degrees to 3 degrees. In no case was motion gained at the expense of joint stability and, at final followup, average flexion and extension were 127 degrees and 4 degrees, respectively. The final range of motion achieved was not affected by the time to manipulation, severity of premanipulation flexion deficit, or concomitant arthroscopic debridement of adhesions. However, knees with premanipulation extension deficits of greater than or equal to 15 degrees achieved significantly less final extension than knees with lesser premanipulation deficits. Overall, manipulations were a safe and effective method for improving both flexion and extension in 86% of the knees that had restricted motion after ACL reconstructions.

Anterior cruciate ligament reconstruction. The effect of tibial tunnel placement on range of motion.

In 111 patients who had anterior cruciate ligament reconstructions, postoperative radiographic measurements of anterior to posterior and medial to lateral location of the tibial tunnels were correlated with the final range of motion achieved. In the 25 patients with extension deficits of 10 degrees or more, placement of the tibial tunnel was more anterior (average, anterior 23% of the tibia) than in the remaining 86 patients with extension deficits of < 10 degrees (average, anterior 29% of tibia). This difference was statistically significant with P < 0.001. Logistic regression analysis revealed that the more anterior the placement of the tibial tunnel, the greater the loss of both flexion (P = 0.01) and extension (P = 0.002). In the 21 patients with full extension but flexion < 130 degrees, placement of the tibial tunnel tended to be more medial (average, medial 40% of the tibia) than in the 65 patients without flexion deficit (average, medial 45% of the tibia). We conclude that placement of the tibial tunnel in the "eccentric," anteromedial position may contribute to the development of flexion and extension deficits after anterior cruciate ligament reconstruction.

Similarity in yolk-platelet structure of an ancient bony fish (Acipenser) and an ancient reptile (Sphenodon).

Lipovitellin-phosvitin crystals from oocytes of the sturgeon (Acipenser boeri L.) and the tuatara (Sphenodon punctatus [Gray]) have been shown to he orthorhombic like all such known crystals from vertebrates higher than cyclostomes. Lattice parameters and projected crystal views also resembled closely the hitherto known cases. The high evolutionary conservation of this crystal structure probably reflects a cell-biological significance of the tertiary structure of crystal constituents, especially of the lipovitellines. A comparative consideration of crystallographic data from cyclostomes and higher vertebrates suggests that cyclostomes started with one species and all higher vertebrates with two species of lipovitellin molecules.

Immunohistological demonstration of insulin and glucagon in islet tissue of reptiles, amphibians and teleosts using epoxy-embedded material and antiporcine hormone sera.

Islet tissue from 2 reptilian, 5 amphibian and 7 teleost species was fixed in glutaraldehyde, embedded in epoxy-resin, stored for up to 3 years, cut in ultrathin sections and stained with the indirect immunofluorescent technique for insulin and glucagon following removal of the plastic. The antisera were directed against porcine insulin and glucagon, or FITC labeled and directed against the globulin fraction of the producer species. Positive results were obtained in species from all vertebrate classes investigated. Insulin demonstration in teleosts was particularly difficult.

Traumatic lateral scapular displacement: an expanded spectrum of associated neurovascular injury.

The clinical entity of "scapulothoracic dissociation" has been reported as an uncommon but devastating shoulder girdle disruption. All previously identified closed injuries have been associated with arterial and brachial plexus compromise; therefore, neurovascular disruption has been presented as an essential diagnostic clinical finding of scapulothoracic dissociation. We have identified and managed four patients who satisfy all the radiographic criteria for scapulothoracic dissociation but who have presented with a spectrum of neurovascular conditions ranging from entirely normal to complete disruption. These patients illustrate a previously unrecognized, or at least unreported, continuum of potential neurovascular compromise associated with disruption of the scapulothoracic articulation. An expanded and more descriptive classification scheme for "traumatic lateral scapular displacement" is proposed to emphasize the spectrum of possible presentations of this injury.

Biomechanical and histological evaluation of the Herbert screw.

The Herbert screw has been demonstrated to have widespread clinical applicability. A biomechanical and histological evaluation of the Herbert screw was conducted to better define its applications. When subjected to pull-out, toggle, and compression testing, in a cancellous bone calf model, it was demonstrated to be biomechanically inferior to the 4.0 mm ASIF cancellous screw. The use of two Herbert screws minimized but did not eliminate this difference. Articular cartilage healing in a rabbit model was consistently demonstrated if the Herbert screw was buried deep to the osteochondral junction. However, toluidine blue histochemical staining showed that the hyaline-like repair cartilage differed qualitatively from normal cartilage. Utilization of the Herbert screw should include an understanding of the limitations of its fixation potential and a recognition of the repair response after intraarticular applications.

Results in patients with craniocerebral trauma and an operatively managed acetabular fracture.

Results in 23 patients with significant craniocerebral trauma (Glasgow Coma Scale less than or equal to 10) and displaced acetabular fracture requiring surgery were reviewed after a minimum follow-up of 1 year. Despite a postoperative anatomic reduction in all but one case, clinical outcome for these hips was poor, with an average Harris hip rating of 59. Patients older than 40 years had a significantly poorer outcome than did younger patients (p = 0.004). Postoperative problems occurred in 70% of patients (n = 16); the largest portion of these represented symptomatic heterotopic bone, which occurred in 61%. None of the four patients who had an anterior ilioinguinal surgical approach had symptomatic heterotopic ossification. The average Glasgow outcome score was 3.9 out of 5, and 20 of the 23 patients, despite a prolonged convalescence, were able to return to independence and self-care. The authors conclude that patients with combined significant craniocerebral trauma and an operatively managed displaced acetabular fracture are likely to have compromised hip function despite a well-executed osteosynthesis. This was especially true for those patients over age 40 in this series. The authors suggest that if the fracture pattern permits it, the operative management of the acetabular fracture in these patients be by an anterior ilioinguinal approach, so as to minimize the formation of heterotopic bone.

Hyperextension mallet finger.

Mallet finger injury of the distal extensor mechanism of a digit represents a spectrum of pathology. The hyperextension variant, characterized by a major intraarticular fracture fragment and volar subluxation of the distal phalanx, requires specific recognition. Its distinctive mechanism of injury requires modification of routine mallet finger management, whether open or closed. Persistent volar subluxation, in our experience, has been associated with consistently unsatisfactory results.

Expanding applications for the Herbert scaphoid screw.

A distinctive new bone screw developed for the management of scaphoid fractures and nonunions promises to have expanding applicability. Its utilization for osteochondral fractures, small joint arthrodeses, osteochondritic lesions, and fractures involving small bones is described. Its unique design affords significant advantages over more conventional management techniques of these problems.

Risk factors for restricted motion after anterior cruciate reconstruction.

A retrospective review of 373 patients who had undergone anterior cruciate ligament (ACL) reconstruction utilizing the central third of the patellar tendon was undertaken to identify those factors that placed a patient at risk for restricted postoperative motion (flexion < or = 125 degrees or flexion contracture > or = 10 degrees). Stepwise logistic regression analysis determined that the variables most strongly correlated with restricted final range of motion (ROM) were open surgery (P = .0008) and reconstruction performed < or = 7 days after the initial injury (P = .004). Age, associated meniscal repair, or associated collateral ligament injuries did not significantly affect the ROM. A subgroup of 204 patients arthroscopically reconstructed more than 7 days post-injury were significantly less likely to have limited motion when ROM exercises were begun within 2 days of surgery (P = .008). These data support delayed, arthroscopic ACL reconstruction followed by early ROM exercises as useful techniques for avoiding postoperative motion problems.

The vascular system of principal islets: semithin-section studies in teleosts fixed by perfusion.

The angioarchitecture of clearly zonated principal islets (central B-cell and peripheral A-cell region) from teleosts has been analyzed in five islets following perfusion fixation and serial sectioning. In contrast to the similar cell-type distribution in the species studied (Gadus morrhua , Myoxocephalus scorpius , Agonus cataphractus , Limanda limanda ) there were three different types of vasculature characterized by centripetal blood flow, centrifugal blood flow, or an intermediate type. The vascular pattern (and the development of the organ capsule) showed inter- and even intraspecies differences. It is suggested that differences in angioarchitecture reflect individually variable interactions of exocrine and endocrine tissue during organogenesis rather than mutual cell-type control via the vascular system.

Limb reconstruction versus amputation decision making in massive lower extremity trauma.

Massive lower extremity trauma, in particular open tibial fractures with associated vascular injuries, presents an immediate and complex decision-making challenge between a limb salvage attempt and primary amputation. Unfortunately, the literature to date is deficient in providing sound and defensible guidelines for primary amputation. Individual patient variables, specific extremity injury characteristics, and associated injuries must all be weighed before a decision can be reached. Further prospective studies are necessary before a well-defined protocol for primary amputation can be properly developed.

Highly conserved lipoprotein assembly in teleost and amphibian yolk-platelet crystals.

Ohlendorf et al. have reported that yolk-platelet crystals in the frog, Xenopus laevis, were orthorhombic (space group P21221) and consisted of elongated asymmetric units (approximately 5.5 x 11.5 x 25 nm). The presence of an orthorhombic lattice in amphibian yolk platelets fulfilling the symmetry requirements of crystals had been missed in earlier structural interpretations. A comparative study of teleost, urodele and anuran yolk-platelet crystals performed in our laboratory has shown the widespread occurrence among equatic vertebrates of an orthorhombic lattice with unit-cell sides similar to those of Xenopus. However, we report here that the space group (P212121) and certain features of the macromolecular complex are at variance with those reported for Xenopus.

Lipoprotein crystals in the yolk platelet of a teleost, Pelvicachromis pulcher (Cichlidae).

Yolk-platelt crystals in the oocytes of the teleost Pelvicachromis pulcher (Cichlidae) were shown, using electron diffraction and tilting of thin-sectioned specimens, to possess an orthorhombic lattice with unit-cells sides a = 8.3 nm, b = 16.6 nm and c = 18.0 nm. They thus closely resemble the crystals known for a newt (Triturus sp.) and a frog (Xenopus laevis).

Diagnostic dilemmas in foot and ankle injuries.

Differential diagnosis of foot and ankle injuries should include stress fractures of the great toe sesamoids, the shaft of the fifth metatarsal, and the tarsal navicular bone; transchondral talar-dome fractures; fractures of the os trigonum; and dislocating peroneal tendons. Diagnosis of these injuries is challenging because the initial roentgenograms often are normal, and special clinical tests and ancillary studies are required.