Comparison of two types of fixation for proximal tibial epiphysiodesis: An experimental study in a rabbit model

Objectives: In this study, we describe a novel hemiepiphysiodesis technique to prevent implant-related perichondrial ring injury in a rabbit model. Materials and methods: Proximal tibial epiphyseal plates of a total of 16 white New Zealand rabbits were used for this animal model. The subjects were divided into three equal groups as follows: Group 1 (Kirschner wire [K-wire]/cerclage), Group 2 (8-plate) right-hind legs, Group 3 (Control) left hind legs. Using anteroposterior radiography, the medial slope angle (MSA), articular line-diaphyseal angle (ALDA), and the angle between screws of 8-plate in lateral X-ray tibial slope angle (TSA) were measured. The radiographs were taken early postoperative (Day 1) and on sacrification day (Week 8). The histological evaluation of the perichondrial ring was made on a 7-mm axial section that stained with Safranin O/fast green at X10 magnification. Results: In both K-wire and 8-plate groups, the early postoperative ALDA and TSA were greater than the sacrification ALDA and TSA (p=0.028 and p<0.001, respectively). The early postoperative MSA was lower than the sacrification MSA in groups, (p<0.001). The MSA in the control group was lower than the K-wire and 8-plate groups (p<0.001 and p=0.009; respectively). The perichondrial ring thickness of the K-wire group was greater than the 8-plate group in histological evaluation (p<0.001). Conclusion: Both of the K-wire and 8-plate groups showed similar angulation effects in the proximal tibia, although histologically less damage to the perichondrial ring was observed in the K-wire group, compared to the 8-plate group.

Abnormalities of the rib growth plate and the periphysis of previously healthy infants and toddlers dying suddenly and unexpectedly

AimsHistological examination of the rib is of critical value in perinatal pathology and points to the health of the child preceding death. The rib is considered ideal because it is the most rapidly growing long bone in infants and demonstrates growth arrest at onset of the insult. We aimed to identify: 1: changes in the perichondrial ring in the rib of infants and children up to 16 months of age dying suddenly at our institution and 2: any association with presence of histological changes of vitamin D deficiency (VDD) /metabolic bone disease (MBD) in the growth plate.MethodsRetrospective review of the perichondrial rib histology and comparison with the presence or absence of histological features of VDD in the growth plate of 167 cases. The cases were anonymised and divided in six age/sex categories.ResultsPeriphyseal abnormalities were only seen in 38% of the cases; of whom 33% had established and 67% had mild changes. Only 14.5% of cases with established histological appearance of VDD at the growth plate had significant PR abnormality; of whom majority (83%) were ≤3 months of age and none ≥9 months old, reflecting a temporal relation with birth and beyond the perinatal period.ConclusionThe histological changes in the perichondrial ring are significantly associated with histological changes of VDD /MBD at the rib growth plate with an Odds Ratio of 3.04.

Visualization of early intramembranous ossification by electron microscopic and spectroscopic imaging.

We present electron microscopic and electron spectroscopic images of putative nucleation sites and early mineral deposits during intramembranous ossification of the murine perichondrial ring. Electron spectroscopic imaging (ESI) permits the quantitative determination and direct visualization of spatial distribution of atomic elements within specimens at high spatial resolution. In this study ESI was used to determine the elemental distributions of phosphorus, sulfur, and calcium. Nucleation and subsequent mineralization in the perichondrial ring occurred sequentially along the longitudinal axis. Proximal regions of the ring contained a matrix with only a few nucleation sites that are characterized in conventional electron micrographs as small loci of low-density material in which dense particles are located. Elemental maps of these sites that we obtained by ESI reveal a sulfur-containing matrix in which localized concentrations of phosphorus occur. With further maturation the loci became centers for the genesis of numerous dense rods or crystals. These mineral deposits contained increased concentrations of P, S, and Ca, compared with the surrounding matrix. The appearance of S at nucleation sites and its persistence in developing mineral deposits suggests that a sulfur-containing moiety may serve as a locus within the osteoid matrix to attain high local concentrations of Ca and P, which leads to the controlled local formation of calcium phosphates. Calcification of the perichondrial ring has been found to occur in the absence of matrix vesicles, which illustrates that these membrane-bounded organelles are not obligatory sites for nucleation in this matrix.