OBJECTIVE: In this study, the effects of sex and birth type on growth performance, withers height (WH), radiographic measurements and selected hormone profiles in Gurcu goat kids were investigated.
METHODS: Twenty kids (single female = 5, single male = 5, twin female = 5, twin male = 5) were included in the study. Body weight (BW), WH, radiographic measurements (humerus length [HL], radius length [RL], proximal humerus epiphyseal plate width [HEP] and distal ulna epiphyseal plate width [UEP]) and biochemical analysis (for serum calcitonin, free triiodothyronine [FT3], free thyroxine [FT4], growth hormone [GH] and insulin-like growth factor-I [IGF-I]) were performed at 1, 3, 5, 7, 9 and 12 months of age.
RESULTS: BW was significantly higher in males starting from the seventh month compared to females (p < 0.05). HL was higher in males at seventh (p = 0.009) and ninth (p = 0.033) months, whereas RL was lower in twins at the third month (p = 0.021). UEP was wider in males at seventh (p = 0.008) and ninth (p = 0.036) months. Closure of HEP was observed in 65% of kids by the 12th month. Calcitonin was lower in twins at third (p = 0.045) and fifth (p = 0.006) months, with changes observed due to group and time effects (p < 0.05), whereas other hormones only changed with time (p < 0.05). Positive correlations were observed between BW, WH, HL, RL and IGF-I. There was a negative correlation between BW, WH, HL, RL, IGF-I and HEP, UEP, calcitonin, FT3, FT4, GH.
CONCLUSIONS: Sex and birth type in Gurcu goat kids may have an impact on growth performance, radiographic measurements and certain hormonal profiles.

Slipped capital femoral epiphysis is a shearing injury through the growth plate of the proximal femur and is the most common hip disorder in adolescence. Delays in diagnosis persist across practice settings despite ongoing innovations in imaging. Recent insights into pathomechanics highlight the importance of femoral head surface morphology and rotational microinstability centered at the epiphyseal tubercle in causing early physeal changes, which can be detected on imaging prior to frank slip. Scrutiny of physeal morphology and comparison to the contralateral hip is critical at all stages of disease progression, and improper technique may result in undue diagnostic delay. Selective use of cross-sectional imaging can be helpful for troubleshooting equivocal early slips and can inform operative technique and adjuvant therapy candidacy in more severe cases. This review provides a comprehensive approach to imaging suspected slipped capital femoral epiphysis, with an emphasis on early detection and potential pitfalls.

The cartilage growth plate is essential for maintaining skeletal growth; however, the mechanisms governing postnatal growth plate homeostasis are still poorly understood. Using approaches of molecular mouse genetics and spatial transcriptomics applied to formalin-fixed, paraffin-embedded (FFPE) tissues, we show that ADGRG6/GPR126, a cartilage-enriched adhesion G protein-coupled receptor (GPCR), is essential for maintaining slow-cycling resting zone cells, appropriate chondrocyte proliferation and differentiation, and growth plate homeostasis in mice. Constitutive ablation of Adgrg6 in osteochondral progenitor cells with Col2a1Cre leads to a shortened resting zone, formation of cell clusters within the proliferative zone, and an elongated hypertrophic growth plate, marked by limited expression of PTHrP but increased IHH signaling throughout the growth plate. Attenuation of Smoothened (SMO)-dependent hedgehog signaling restored the Adgrg6 deficiency-induced expansion of hypertrophic chondrocytes, confirming that IHH signaling can promote chondrocyte hypertrophy in a PTHrP-independent manner. In contrast, postnatal ablation of Adgrg6 in mature chondrocytes with AcanCreERT2, induced after the formation of the resting zone, does not affect PTHrP expression but causes an overall reduction of growth plate thickness marked by increased cell death specifically in the resting zone cells and a general reduction of chondrocyte proliferation and differentiation. Spatial transcriptomics reveals that ADGRG6 is essential for maintaining chondrocyte homeostasis by regulating osteogenic and catabolic genes in all the zones of the postnatal growth plates, potentially through positive regulation of SOX9 expression. Our findings elucidate the essential role of a cartilage-enriched adhesion GPCR in regulating cell proliferation and hypertrophic differentiation by regulation of PTHrP/IHH signaling, maintenance of slow-cycle resting zone chondrocytes, and safeguarding chondrocyte homeostasis in postnatal mouse growth plates.
The cartilage growth plate is an essential structure for skeletal growth, however, the mechanisms that govern growth plate homeostasis are still poorly understood. In this study, we showed that an adhesion G protein-coupled receptor (GPCR) named ADGRG6 plays an essential role in maintaining the slow-cycling cells in the resting zone of the growth plate and directing appropriate proliferation and differentiation of the growth plate chondrocytes. Using a technique called spatial transcriptomics, we compared the gene expression profiles in control and Adgrg6 mutant growth plates and found that ADGRG6 prevents premature hypertrophic differentiation of the growth plate chondrocytes by negatively regulating Indian Hedgehog (IHH) signaling. In summary, our findings highlighted the essential role of a cartilage-enriched GPCR in maintaining growth plate homeostasis through IHH signaling.

Insulin-like growth factor (IGF) signaling is required for proper growth and skeletal development in vertebrates. Consequently, its dysregulation may lead to abnormalities of growth or skeletal structures. IGF is involved in the regulation of cell proliferation and differentiation of chondrocytes. However, the availability of bioactive IGF may be controlled by antagonizing IGF binding proteins (IGFBPs) in the circulation and tissues. As the metalloproteinase PAPP-A specifically cleaves members of the IGFBP family, we hypothesized that PAPP-A activity liberates bioactive IGF in cartilage. In PAPP-A knockout mice, the femur length was reduced and the mice showed a disorganized columnar organization of growth plate chondrocytes. Similarly, zebrafish lacking pappaa showed reduced length of Meckel\'s cartilage and disorganized chondrocytes, reminiscent of the mouse knockout phenotype. Expression of chondrocyte differentiation markers (sox9a, ihha, and col10a1) was markedly affected in Meckel\'s cartilage of pappaa knockout zebrafish, indicating that differentiation of chondrocytes was compromised. Additionally, the zebrafish pappaa knockout phenotype was mimicked by pharmacological inhibition of IGF signaling, and it could be rescued by treatment with exogenous recombinant IGF-I. In conclusion, our data suggests that IGF activity in the growing cartilage, and hence IGF signaling in chondrocytes, requires the presence of PAPP-A. The absence of PAPP-A causes aberrant chondrocyte organization and compromised growth in both mice and zebrafish.

Pregestational diabetes mellitus (PGDM) has an impact on fetal bone formation, but the underlying mechanism is still obscure. Although miRNAs have been extensively investigated throughout bone formation, their effects on fetal bone development caused by PGDM still need clarification. This study intends to examine the mechanism by which hyperglycemia impairs the bone formation of offspring via miR-322-5p (miR-322). In this study, miR-322 was selected by systemically screening utilizing bioinformatics and subsequent validation experiments. Using streptozotocin (STZ)-induced diabetic mice and ATDC5 cell lines, we found that miR-322 was abundantly expressed in the proliferative and hypertrophic zones of the growth plate, and its expression pattern was disturbed in the presence of hyperglycemia, suggesting that miR-322 is involved in the chondrocyte proliferation and differentiation in absence/presence of hyperglycemia. This observation was proved by manipulating miR-322 expression in ATDC5 cells by transfecting mimic and inhibitor of miR-322. Furthermore, Adamts5, Col12a1, and Cbx6 were identified as the potential target genes of miR-322, verified by the co-transfection of miR-322 inhibitor and the siRNAs, respectively. The evaluation criteria are the chondrocyte proliferation and differentiation and their relevant key gene expressions (proliferation: Sox9 and PthIh; differentiation: Runx2 and Col10a1) after manipulating the gene expressions in ATDC5 cells. This study revealed the regulative role miR-322 on chondrocyte proliferation and differentiation of growth plate by targeting Adamts5, Col12a1, and Cbx6 in hyperglycemia during pregnancy. This translational potential represents a promising avenue for advancing our understanding of bone-related complications in diabetic pregnancy and mitigating bone deficiencies in diabetic pregnant individuals, improving maternal and fetal outcomes.

BACKGROUND: The incidence of anterior cruciate ligament (ACL) injuries in children is on the rise. Despite this trend, the optimal management of these injuries remains a matter of ongoing debate. In this light, our study seeks to assess the clinical, radiological, and functional outcomes of transphyseal ACL reconstruction in preadolescent patients in the medium-term.
METHODS: This prospective study included preadolescent patients aged up to 12 years who underwent ACL transphyseal reconstruction between 2010 and 2020 and had a minimum follow-up of 2 years. Clinical assessments encompassed joint stability and range of motion. Furthermore, leg length discrepancy (LLD) and femorotibial alignment were evaluated both clinically and radiologically using full-length lower limb standing radiographs. Pre- and postoperative functional outcomes were assessed using the International Knee Documentation Committee (IKDC) and Lysholm scales, and the return to normal sports activity was evaluated using the ACL-Return to Sport after Injury (ACL-RSI) scale. Complications and relevant follow-up data were also recorded. Statistical analyses were conducted to evaluate these outcomes.
RESULTS: A total of 35 preadolescent patients, consisting of 24 males and 11 females, with a mean age at surgery of 11.2 ± 0.7 years (8.7-12), were included in the study. The mean follow-up was 52.3 ± 20.7 months (24.1-95.9). No significant growth disturbances or clinically relevant LLD were evidenced. All patients demonstrated clinically stable knees with full range of motion at the 2-year follow-up. There were statistically significant improvements in pre- and postoperative IKDC (39.3 ± 13.5 vs. 99.7 ± 0.8, p < 0.005) and Lysholm scores (48.2 ± 15.1 vs. 99.6 ± 1.4, p < 0.005). All but two patients were able to return to their pre-injury level of sports activity, with a mean ACL-RSI score of 93.5 ± 1.3. The analysis revealed an 8.6% rerupture rate and an 11.4% rate of contralateral ACL injuries, with 5-year survival rates of 92.3% and 88.8%, respectively. Subgroup analyses based on age, gender, surgical delay, or associated meniscal lesions did not reveal any significant differences in functional outcomes. Additionally, there was no discernible relationship between age or timing of ACL reconstruction and the risk of meniscal injuries.
CONCLUSIONS: Our study reinforces the value of ACL reconstruction in skeletally immature preadolescent patients, with transphyseal technique proven to be a safe, effective, and technically simpler option, even for children under the age of 12. The findings indicate excellent functional outcomes, a high rate of successful return to sporting activities, and minimal to no incidence of growth-related complications in the medium-term.
METHODS: Level II, prospective comparative cohort study, before and after intervention.

Fibronectin (FN) is a ubiquitous extracellular matrix glycoprotein essential for the development of various tissues. Mutations in FN cause a unique form of spondylometaphyseal dysplasia, emphasizing its importance in cartilage and bone development. However, the relevance and functional role of FN during skeletal development has remained elusive. To address these aspects, we have generated conditional knockout mouse models targeting the cellular FN isoform in cartilage (cFNKO), the plasma FN isoform in hepatocytes (pFNKO), and both isoforms together in a double knockout (FNdKO). We used these mice to determine the relevance of the two principal FN isoforms in skeletal development from P1 to the adult stage at two months. We identified a distinct topological FN deposition pattern in the mouse limb during different gestational and postnatal skeletal development phases, with prominent levels at the resting and hypertrophic chondrocyte zones and in the trabecular bone. Cartilage-specific cFN emerged as the predominant isoform in the growth plate, whereas circulating pFN remained excluded from the growth plate and confined to the primary and secondary ossification centers. Deleting either isoform independently (cFNKO or pFNKO) yielded only relatively subtle changes in the analyzed skeletal parameters. However, the double knockout of cFN in the growth plate and pFN in the circulation of the FNdKO mice significantly reduced postnatal body weight, body length, and bone length. Micro-CT analysis of the adult bone microarchitecture in FNdKO mice exposed substantial reductions in trabecular bone parameters and bone mineral density. The mice also showed elevated bone marrow adiposity. Analysis of chondrogenesis in FNdKO mice demonstrated changes in the resting, proliferating and hypertrophic growth plate zones, consistent alterations in chondrogenic markers such as collagen type II and X, decreased apoptosis of hypertrophic chondrocytes, and downregulation of bone formation markers. Transforming growth factor-β1 and downstream phospho-AKT levels were significantly lower in the FNdKO than in the control mice, revealing a crucial FN-mediated regulatory pathway in chondrogenesis and bone formation. In conclusion, the data demonstrate that FN is essential for chondrogenesis and bone development. Even though cFN and pFN act in different regions of the bone, both FN isoforms are required for the regulation of chondrogenesis, cartilage maturation, trabecular bone formation, and overall skeletal growth.

The growth plate is a cartilage structure at the end of long bones which mediates growth in children. When fractured, the formation of bony repair tissue known as a \"bony bar\" can occur and cause limb deformities. There are currently no effective clinical solutions for the prevention of the bony bar formation or regeneration of healthy growth plate cartilage after a fracture. This study employs previously developed alginate/chitosan polyelectrolyte complex (PEC) hydrogels as a sustained release vehicle for the delivery of short-interfering RNA (siRNA). Specifically, the siRNA targets the p38-MAPK pathway in mesenchymal stem cells (MSCs) to prevent their osteogenic differentiation. In vitro experimental findings show sustained release of siRNA from the hydrogels for 6 months. Flow cytometry and confocal imaging indicate that the hydrogels release siRNA to effectively knockdown GFP expression over a sustained period. MAPK-14 targeting siRNA was used to knockdown the expression of MAPK-14 and correspondingly decrease the expression of other osteogenic genes in MSCs in vitro over the span of 21 days. These hydrogels were used in a rat model of growth plate injury to determine whether siMAPK-14 released from the gels could inhibit bony bar formation. No significant reduction of bony bar formation was seen in vivo at the one concentration of siRNA examined. This PEC hydrogel represents a significant advancement for siRNA sustained delivery, and presents an interesting potential therapeutic delivery system for growth plate injuries and other regenerative medicine applications.

Tibial dyschondroplasia (TD) is a severe bone disease that affects fast-growing broiler chickens and causes economic loss. Despite previous studies, the regulatory mechanism of TD remains unclear and is thought to be primarily based on thiram induction, which may differ from that of naturally occurring diseases. To better understand TD, a digital X-ray machine was used in the present study to determine its incidence in four hundred yellow-feathered broiler chickens. The results showed that the incidence of TD was 22% after 6 weeks and gradually decreased after 8 and 10 weeks. The body weight of broilers with TD decreased significantly compared to that of NTD broilers. In addition, the length and density of the tibia were reduced after eight and 10 weeks, and the density of the tibia was reduced after 6 weeks compared with the NTD chickens. This study also examined tibial quality parameters from TD (n = 12) and NTD broilers (n = 12) and found that bone mineral content, bone mineral density, bone ash content, calcium content, and phosphorus content were significantly reduced in TD broilers. Transcriptome analysis revealed 849 differentially expressed genes (DEGs) in the growth plate between TD (n = 6) and NTD groups (n = 6). These genes were enriched in ECM-receptor interaction, cytokine-cytokine receptor interaction, calcium signaling pathway, and TGF-β signaling. Genes encoding the alpha chain of type XII collagen, that is, COL1A1, COL5A1, and COL8A1) were identified as critical in the regulatory network of TD. Gene set enrichment analysis (GSEA) revealed that the pathways of cartilage development, circulatory system development, and nervous system development were changed in the growth plates of TD birds. In the blood transcriptome, 12 DEGs were found in TD (n = 4) and NTD chickens (n = 4), and GSEA revealed that the pathways from TD broilers\' blood related to the phagosome, linoleic acid metabolism, monoatomic ion homeostasis, and calcium ion transport were downregulated. This study provides a comprehensive understanding of TD, including its effects on tibial quality, tibial changes, and the circulatory system, along with identifying important genes that may lead to the development of TD.

Tartrate-resistant acid phosphatase (TRAP) serum levels reflect osteoclast number, bone remodeling activity, and fracture risk. Deletion or loss of function of TRAP results in short stature in mice and man. Yet, the impact and mechanisms of TRAP for the site- and sex-specific development of bone and cartilage is not well understood. Here, we use a global TRAP knockout (TRAPKO) and wildtype littermate control (WT) mice of both sexes to investigate TRAP as a possible sex- and site-specific regulator of bone and growth plate development. TRAPKO mice of both sexes weighed less and had shorter tibial length than their WT, features that were more accentuated in male than female TRAPKO mice. These changes were not associated with a general reduction in growth as not all organs displayed a proportionally lower mass, and serum IGF-1 was unchanged. Using μCT and site-specificity analysis of the cortical bone revealed wider proximal tibia, a higher trabecular thickness, and lower trabecular separation in male TRAPKO compared to WT mice, an effect not seen in female mice. Histomorphometric analysis revealed that the growth plate height as well as height of terminal hypertrophic chondrocytes were markedly increased, and the number of columns was decreased in TRAPKO mice of both sexes. These effects were more accentuated in female mice. Proliferation and differentiation of bone marrow derived macrophages into osteoclasts, as well as C-terminal cross links were normal in TRAPKO mice of both sexes. Collectively, our results show that TRAP regulates bone and cartilage development in a sex-and site-specific manner in mice.