Reliability and reproducibility of radiographic interpretation of proximal humeral fracture pathoanatomy.

Recent studies have demonstrated inconsistencies in the use of certain images for classifying proximal humerus fractures. Our purpose was to determine whether three-dimensional computed tomography or the level of expertise of the observers would improve the reliability and reproducibility of identifying specific anatomic fragments in proximal humerus fractures. Two groups of observers, nonexperts and experts in shoulder surgery, were asked to review the radiographs and three-dimensional computed tomography scans of 12 patients with proximal humerus fractures. Observers were asked to identify displaced fracture fragments, dislocation, and articular surface fractures. Both groups of observers displayed suboptimal reliability for the identification of displaced fracture fragments. The addition of three-dimensional computed tomography scans did not improve the reliability or reproducibility. Poor agreement for the purpose of classification seems to occur at the most fundamental level, the pathoanatomic description of the fracture. Inconsistencies may have been due to imprecise identification and measurement of individual fracture fragments, differing interpretations of the pathoanatomy, or both.

Elucidation of the centromere involvement in an inversion (13) by fluorescent in situ hybridisation.

A newborn infant with phenotypic features of trisomy for distal 13q was found to have recombinant inversion duplication involving the (13)(q22-->qter) region. Parental karyotypes showed that the mother had a normal 46,XX complement and the father had an apparently balanced pericentric inversion of a chromosome 13. Because of the unusual nature of the inversion, the exact position of the centromere on the father's inverted chromosome 13 was difficult to assign by GTG banding, even on prometaphase chromosomes. CBG and NOR banding were not informative in determining the location of the centromere. Fluorescent in situ hybridisation with an alpha satellite DNA probe for D13Z1/D21Z1 helped in confirming the exact position of the centromere in the rearranged paternal chromosome. Thus, the origin of the proband's abnormal chromosome 13 was clarified.

Experimental muscle strain injury. Early functional and structural deficits and the increased risk for reinjury.

The structural and functional strength of a muscle immediately after an experimentally created strain injury was examined to provide clinically relevant information for the early treatment of muscle strain injuries. The extensor digitorum longus muscles of 12 adult male rabbits were studied. Contractile force and shortening, and peak load were determined for control muscles. A nondisruptive strain injury was created by stretching the experimental muscles just short of complete rupture. Contractile force generation and shortening, and peak load were determined after the experimental strain injury. Peak load was 63% and elongation to rupture was 79% for the experimental muscles relative to the controls. Statistically significant lower values for contractile force generation and shortening were also seen in the experimental muscles. Histologic and gross examinations revealed that incomplete disruptions occurred near the distal muscle-tendon junction. These experimental data suggest clinical implications, such as 1) a muscle-tendon unit is significantly more susceptible to injury following a strain injury than normal muscle, 2) early return to the uncontrolled environment of athletic competition may place the injured muscle at risk for further injury, and 3) therapeutic regimens designed to achieve an early return to competition may further increase the risk for additional injury by eliminating protective pain mechanisms. Although the decrements in peak load and elongation to failure are less than normal muscle, the values seem high enough to allow mobilization of the injured extremity and functional rehabilitation.

Deletion of chromosome 15pter-->q11.2 due to t(Y;15) in a boy with Prader-Willi syndrome.

Chromosome analysis of lymphocytes from a patient with the clinical presentation of Prader-Willi syndrome showed the presence of 45 chromosomes, including a der(Y) resulting from an unbalanced t(Y;15)(q12;q11.2). In situ hybridization using DYZ3 and DYZ2 showed positive signals at the paracentromeric region on the short arm and at the heterochromatic region of the long arm of the Y chromosome, respectively. The Prader-Willi syndrome in this patient is caused by the deficiency of a very small region involving 15cen-->q11.2.

A randomized prospective study to assess the effect of the use of home urinary luteinizing hormone detection on the efficiency of donor insemination.

A study was carried out to establish whether the use of home urinary luteinizing hormone (LH) detection to predict ovulation could decrease the number of clinic visits required for the management of a donor insemination (DI) cycle, and thus optimize use of clinic resources without adversely affecting pregnancy rates. This was a randomized prospective study carried out at a donor insemination clinic in Oxford, England. Fifty-six patients participated in the trial; 27 used home urinary ovulation detection for a total of 111 cycles and 29 had a total of 123 DI cycles managed by routine clinical methods. There was a significant reduction in the number of visits per cycle (P less than 0.001) if home kits for detection of ovulation were used. There was no significant difference in the monthly fecundity or cumulative conception rates. We conclude that the use of home urinary LH detection in donor insemination can reduce patient attendance at the clinic and optimize the use of medical resources without adversely affecting pregnancy rates.

Identification of the origin of centromeres in whole-arm translocations using fluorescent in situ hybridization with alpha-satellite DNA probes.

We detected 2 patients with whole-arm translocations resulting in a derivative chromosome consisting of 18q and 21q. Because the breakpoints were near the centromere, classical cytogenetic techniques could not determine the centromeric origin of the derivative chromosomes. Using nonradioactive in situ hybridization with a chromosome 18 alpha-satellite DNA probe (D18Z1), the centromeres in the abnormal chromosomes were determined to be from chromosome 18. The abnormality in one patient resulted in monosomy 18p with a karyotype 45,XX, -18, -21, + der(18)t(18;21) (p11;q11)mat complement. The second patient with a 46,XX, -21, + der(18)t(18;21)(p11;q11) de novo karyotype had complete trisomy of 18q. In both cases the appropriate phenotype was observed.

Viscoelastic properties of muscle-tendon units. The biomechanical effects of stretching.

Most muscle stretching studies have focused on defining the biomechanical properties of isolated elements of the muscle-tendon unit or on comparing different stretching techniques. We developed an experimental model that was designed to evaluate clinically relevant biomechanical stretching properties in an entire muscle-tendon unit. Our objectives were to characterize the viscoelastic behavior of the muscle-tendon unit and to consider the clinical applications of these viscoelastic properties. Rabbit extensor digitorum longus and tibialis anterior muscle-tendon units were evaluated using methods designed to simulate widely used stretching techniques. Additionally, the effects of varying stretch rates and of reflex influences were evaluated. We found that muscle-tendon units respond viscoelastically to tensile loads. Reflex activity did not influence the biomechanical characteristics of the muscle-tendon unit in this model. Experimental techniques simulating cyclic stretching and static stretching resulted in sustained muscle-tendon unit elongations, suggesting that greater flexibility can result if these techniques are used in the clinical setting. With repetitive stretching, we found that after four stretches there was little alteration of the muscle-tendon unit, implying that a minimum number of stretches will lead to most of the elongation in repetitive stretching. Also, greater peak tensions and greater energy absorptions occurred at faster stretch rates, suggesting that the risk of injury in a stretching regimen may be related to the stretch rate, and not to the actual technique. All of these clinically important considerations can be related to the viscoelastic characteristics of the muscle-tendon unit.