Three-dimensional architecture of the acetabular labrum in the human hip joint

Structure, composition and anisotropic swelling of the bovine acetabular labrum

The fibro-cartilaginous labrum surrounds the acetabular rim and is important for hip joint stability and sealing. Sealing may be enhanced by swelling pressure within the normal labrum. Swelling of the degenerated or torn labrum might occur and potentially contribute to the development of osteoarthritis, through altered load transmission. This study aimed to characterize the three-dimensional swelling behaviour, the collagen fiber orientation and spatial proteoglycan distribution of the bovine acetabular labrum. Specimens were harvested from bovine donors (192-652 days, male, n = 6 donors). Structure was analyzed by scanning electron microscopy, histology, and dimethylmethylene blue assay. Specimen dimensions were measured before and after incubation in phosphate buffered saline to assess the swelling. Results showed that the articulating surface is composed of a collagen mesh network. Collagen fiber bundles showed a low degree of alignment close to the surface and were circumferentially aligned in the deep tissue. Proteoglycans were identified clustered between the collagen bundles. Glycosaminoglycan content was 10 x lower than that of cartilage (23.1 ± 6.4 compared to 299.5 ± 19.1 μg/mg dry weight) with minor regional differences. Specimens swelled significantly more in the orthogonal direction (swelling ratio 124.7 ± 10.2%) compared to the swelling parallel to the articulating surface (108.8 ± 6.1% and 102.8 ± 4.1%). In the deep tissue, swelling was also restricted in the main collagen fiber bundle direction (circumferentially), with a swelling ratio of 109.5 ± 4.0% in the main fiber bundle direction compared to 126.8 ± 7.3 % and 122.3 ± 5.8% radially. The findings demonstrate that the labrum shows anisotropic swelling properties, which reflect the anisotropy in the tissue structure and inter-fiber localisation of proteoglycans.

Effects of different pelvic osteotomies on acetabular morphology in developmental dysplasia of hip in children

Developmental dysplasia of hip seriously affects the health of children, and pelvic osteotomy is an important part of surgical treatment. Improving the shape of the acetabulum, preventing or delaying the progression of osteoarthritis is the ultimate goal of pelvic osteotomies. Re-directional osteotomies, reshaping osteotomies and salvage osteotomies are the three most common types of pelvic osteotomy. The influence of different pelvic osteotomy on acetabular morphology is different, and the acetabular morphology after osteotomy is closely related to the prognosis of the patients. But there lacks comparison of acetabular morphology between different pelvic osteotomies, on the basis of retrospective analysis and measurable imaging indicators, this study predicted the acetabular shape after developmental dysplasia of the hip pelvic osteotomy in order to help clinicians make reasonable and correct decisions and improve the planning and performance of pelvic osteotomy.

A morphological study of adipose-derived stem cell sheets created with temperature-responsive culture dishes using scanning electron microscopy

Adipose-derived stem cell (ADSC) sheets have potential to be effective in various therapies. In this study, we first demonstrated that a cell sheet composed of human ADSCs could be created using a new temperature-responsive culture dish from the DIC Corporation. The dish can cause detachment of adherent cells due to temperature changes, but a few morphological analyses have evaluated the presence or absence of damage on the detached surface of cell sheet. To characterize our ADSC sheet, we tried to observe the surface of ADSC sheets with scanning electron microscope (SEM) using the ionic liquid, which enables the rapid preparation of samples. No damage was found on the surface of the ADSC sheets on the side that had been in contact with the surface of the culture dishes. In addition, when the transcriptomes of the harvested cell sheets were compared with those of monolayer cultures, no up-regulation of cell death related genes were detected. These results propose that the detachment from temperature-responsive culture dish causes no serious damage on the prepared ADSC sheet. It is also suggested that the SEM with ionic liquids is a useful and rapid method for the analysis of ADSC sheets for therapy.

Microvascular system of hip joint constituents with special reference to ultrastructural findings and early arteriosclerosis

This study aimed to examine the ultrastructure of the arteries of the synovium, acetabular labrum, and ligamentum teres of the hip joint using light, scanning electron, and transmission electron microscopes to identify features of early arteriosclerosis. Tissues collected from three patients (under 40 years of age) with osteonecrosis of the femoral head were immersed in 8 N HCl at 60 °C for 20 min to digest collagen fibers for scanning electron microscopy. Tortuous arterioles and arteries were noted in the joint components, including the synovium, acetabular labrum, and ligamentum teres. The ultrastructure of the arterioles appeared normal; however, intimal thickening was found in most arteries. The thickened intima had abundant elastic fibers and many smooth muscle cells (which were of a synthetic phenotype because they had a few actin filaments and well-developed rough endoplasmic reticulum). This study illustrates that arteriosclerotic changes are present in tortuous arteries in the synovium, acetabular labrum, and ligamentum teres of the hip joint even from a relatively young age and suggests that meandering blood vessels may be the preferred foci of arteriosclerosis.

BMP-2 Modified Electrospun Scaffold for Acetabular Labral Reconstruction Promotes Collagen Fiber Regeneration in a Porcine Model

BACKGROUND

Acetabular labral tear is one of the contributing factors to early hip osteoarthritis. Patients with symptomatic labral tears may require surgical treatment, and labral reconstruction is indicated in cases of irreparable tears.

PURPOSE

The purpose of the study was to construct the bone morphogenic protein 2 (BMP-2) electrospun scaffold for acetabular labral reconstruction and analyze the composition of the labrum and the influence of collagen fiber distribution in regenerated tissue on the biomechanical properties of labrum.

STUDY DESIGN

Controlled laboratory study.

METHODS

Eighteen mature male miniature pigs were selected for labral reconstruction in vivo. The animals were divided into 3 groups, including the autologous tendon group (T group), dopamine/polylactic acid-polyethylene glycol (PELA) electrospun group (DP group), and dopamine/PELA electrospun/BMP-2 group (DPB group), and the native labra were used as the control group. The microstructure of the reconstructed labrum was analyzed by scanning electron microscopy. Histologic and immunohistochemistry sections were used to evaluate the composition and structure of reconstructed labrum. The related gene expression was tested via quantitative reverse transcriptase-polymerase chain reaction test. The compressive and tensile properties of tissues were evaluated using the elasticity test device.

RESULTS

Hematoxylin and eosin staining showed that the DP group and the T group were mainly composed of fibroblasts. The alignment of fibers was irregular. In the DPB group, the reconstructed tissues were composed of fibroblasts and chondrocytes, with parallel fibers and denser structure. The native labrum was composed of a large number of fibroblasts, which were arranged orderly and parallel, and there was almost no vascular proliferation. Under scanning electron microscopy, the reconstructed tissue of the DBP group was more similar to the native labral structure, forming a denser, clear-layered collagen fibrous structure, while the fiber alignment of the DP and T groups was irregular. The contents of type I, II, and III collagen (COL1, COL2, and COL3, respectively) were upregulated in labrum reconstructed with the DPB scaffold, while the gene expressions did not increase in the DP and T groups. The tensile and compressive properties of the implants in the DPB group were significantly enhanced.

CONCLUSION

BMP-2 modified electrospun scaffold promotes collagen regeneration and osteogenic differentiation and is associated with better biomechanical performance of the reconstructed labrum.

CLINICAL RELEVANCE

This study demonstrated that BMP-2 modified electrospun scaffold could induce the regeneration of collagen and osteogenic differentiation and provide better biomechanical performance in labral reconstruction. This scaffold could be used in clinical practice after further improvement.

Acetabular labral reconstruction with medial meniscal allograft: preliminary results of a new surgical technique

PURPOSE

Reconstruction of the acetabular labrum during femoroacetabular impingement (FAI) surgery is accepted when the labrum is deficient and irreparable. Here we describe a novel technique using fresh-frozen medial meniscal allograft for labral reconstruction during surgical hip dislocation for correction of pincer FAI due to acetabular overcoverage.

METHODS

The results from seven hips (six patients) that underwent this procedure with 1 year minimum follow-up, and radiographs are presented.

RESULTS

Six of the seven hips had improvements in pain, hip flexion, hip abduction, and Merle d'Aubigné-Postel scores. Only one patient with pre-existing osteoarthritis underwent reoperation with conversion to total hip arthroplasty. All digastric trochanteric osteotomies healed, and there were no cases of femoral head osteonecrosis or progression of Tönnis grades.

CONCLUSIONS

The medial meniscus is a morphologically and clinically suitable option for labral reconstruction and effectively restores the hip fluid seal.

Histological evaluation of the acetabular labrum after bipolar hip hemiarthroplasty: a case report

We report herein the microstructure of the acetabular labrum obtained from a patient with stem loosening but without bipolar cup migration who had undergone hemiarthroplasty for femoral neck fracture 18 years ago. We used light and scanning electron microscopy to investigate the influence of bipolar cup on acetabular labrum in vivo. Deparaffinized blocks were treated with 2 N NaOH to digest the cell matrix, allowing the collagen fibers, constituting the acetabular labrum, to be observed under scanning electron microscopy. Although chondrocyte atrophy was seen, the basic structure was not different from the normal tissue images of the elderly. However, in the deep part of the acetabular labrum, there was an area that was not stained with Alcian blue observed with light microscopy, and there was an amorphous tissue without type II collagen fibrils observed with scanning electron microscopy. These findings proved that the acetabular labrum has partially degenerated over the long term after bipolar hemiarthroplasty, and that the acetabular labrum can survive in vivo in such a condition. Given that hemiarthroplasty has a possibility to preserve the face-to-face tissue in the long term in vivo, it may be one of the valuable options for modern or future joint reconstruction surgery.