Navigation for lower limb alignment during internal fixation of complex tibial-plateau fractures.

In complex fractures of the proximal tibial metaphysis and epiphysis, possible adverse outcomes after internal fixation include not only joint surface incongruity, but also lower limb malalignment requiring revision surgery. Navigation has been proven effective for the intraoperative control of lower limb alignment during osteotomy and knee arthroplasty. In complex traumatic fractures, temporary fixation by a locking screw plate allows sensor positioning followed by navigation maneuvers to adjust lower limb alignment. If malalignment is found, the construct can be modified economically by altering the diaphyseal fixation without modifying the metaphyseal screws. The objective of this study was to describe the use of navigation in three patients who required internal fixation of tibial-plateau fractures.

Gender differences in knee angle when landing from a drop-jump.

Twenty (10 men and 10 women) healthy, height-matched patients (mean patient age: 28+/-5 years) participated in a study testing the (null) hypothesis that no significant gender differences would be found in the knee flexion angle upon impact from a drop-landing. Patients performed three unconstrained jumps from three vertical heights (20, 40, and 60 cm) onto a concrete floor. Reflective markers were placed on the right side of the body at six sites: the head of the fifth metatarsal, the lateral malleolus, the lateral femoral condyle, the greater trochanter, the posterosuperior iliac spine, and the anterosuperior iliac spine. Ankle, knee, and hip angles in the sagittal plane were then measured at 120 Hz using a two-dimensional motion analysis system. Significant gender differences in knee flexion angles were found at ground impact during the drop-landing (P<.05). The largest gender difference in knee angle occurred when landing from a height of 60 cm: men landed with 16 degrees of knee flexion, whereas women landed with a significantly straighter knee flexion angle of 7 degrees (P<.05). A similar gender difference was found when landing from the medium jump height (40 cm). In this sample, women landed with a straighter knee than did age- and height-matched men.

Asymmetry of methylation with FMR-1 full mutation in two 45,X/46,XX mosaic females associated with normal intellect.

The full FMR-1 mutation is known to cause the fragile X syndrome [Fra(X)], but variable expression in females, including normal to deficient intellect, may be related to random X-inactivation (lyonization). We have evaluated 2 mosaic 45,X/46,XX females who are cytogenetically fra(X) positive, have an FMR-1 full mutation, and are of normal intellect. There were 50% fra(X) chromosomes in the 45,X cells of one of the females; this has not been reported previously. In both patients, there was a strong asymmetry of FMR-1 methylation with the normal allele being totally or 90% unmethylated and the mutant allele being similarly methylated. Thus, the apparent selective inactivation of the full mutant FMR-1 allele appears to have resulted in limited expression with normal intellect. The presence of the fra(X) chromosome in 45,X cells is unique; however, there may be no relationship to the asymmetric inactivation of the mutant allele which could be due to chance or a mechanism yet to be delineated.

Kallmann syndrome associated with complex chromosome rearrangement.

We report on a male with Kallmann syndrome (KS) and an apparently balanced complex chromosome rearrangement (CCR): 46,XY,t(3; 9)(9;12)(q13.2;q21.2p13;q15). This is the first known report of a CCR in the KS and the second reported case of a definitive autosomal chromosome abnormality with KS. Possible relationships between the cytogenetic abnormality and KS are discussed.

Three-generation dominant transmission of the Silver-Russell syndrome.

We report on 7 patients with the Silver-Russell syndrome (SRS) in two 3-generation families. Three patients in each of the families had an undergrowth of the left side of the body when compared with the normal right side. The clinical courses were mild as compared to the severity sometimes described in sporadic cases. These patients and a review of 190 SRS cases from the literature showed that there were 23 families in which 38 patients had completely expressed SRS. In 17 of the families, multiple maternal relatives had complete or partial expressions of the SRS. Most SRS patients have been reported to occur sporadically; however, of the 197 propositi analyzed, 19% had more than one affected individual in a family and several different modes of inheritance could have been responsible. Two families (8.7%) had spontaneous dominant mutations (twins) and possible autosomal recessive transmission was present in 4 families (17.4%). Because no male-to-male transmission has yet been documented in the 21 families in the literature and the two families reported here, X-linked dominant inheritance is a possibility in 17 families (74%). Thus, although sporadic occurrences and genetic heterogeneity appear to be involved in the SRS, dominant inheritance may be a major causal factor.