The Influence of Acetabular Morphologic Variations on the Cup Position in Total Hip Arthroplasty for Crowe type III Dysplastic Hip

Background: We aimed to (1) evaluate the acetabular morphologic variations of Crowe III hips; (2) study the influence of different morphologies on the cup position in total hip arthroplasty.Methods: From November 2008 to February 2019, we retrospectively evaluated 101 patients (110 hips) with Crowe III developmental dysplasia of the hip. We classified Crowe III hips into two subtypes, the IIIA when the acetabular roof was extensively deficient and the junction between the false and the true acetabulum was indistinct, and the IIIB when there is a significant crest between the false and the true acetabulum. Based on the radiographs, we measured the morphological characteristic of the acetabulum and the postoperative cup position.Results: The false acetabulum of IIIB hips had larger Tonnis angle and smaller center-edge angle than the IIIA hips. The width of true acetabular roof in the IIIB hips was thicker than the IIIA group. Fifty-one (100%) IIIA hips and 48 (81.4%) IIIB hips were reconstructed using high hip center while 11 (18.6%) IIIB hips were reconstructed anatomically. The mean vertical distance of center of rotation in the IIIA group was 33.5±4.5 mm while it was 31.2±6.3 mm in the IIIB group (p=0.040). The vertical distance of the hip center was positively correlated with the height of dislocation in the IIIA group (r=0.493, p<0.001). According to the four-zone system, in the IIIA group, 5 hips were located in the inferomedial zone, 23 hips in the superomedial zone, 22 hips in the superolateral zone and 1 hip in the inferolateral zone. In the IIIB group, the corresponding numbers were respectively 15, 17, 1 and 5. Compared with the IIIA group, there were more IIIB hips located in the inferomedial zone (p=0.008) and less in the superolateral zone (p=0.033).Conclusions: There are distinct morphologic subtypes based on the relationship between the false and the true acetabulum. More bone stock located in the superior wall of the true acetabulum can bring more possibilities for anatomical reconstruction, and lower the height of center of rotation when using high hip center.

Downregulation of miR-1-3p expression inhibits the hypertrophy and mineralization of chondrocytes in DDH

Background Developmental dysplasia of the hip (DDH) is a highly prevalent hip disease among children. However, its pathogenesis remains unclear. MicroRNAs (miRNA) are important regulators of cartilage development. In a previous study, high-throughput miRNA sequencing of tissue samples from an animal model of DDH showed a low level of miR-1-3p in the cartilage of the acetabular roof (ARC), but its role in DDH pathogenesis was not addressed. Therefore, our aim here was to investigate the effects of miR-1-3p in the ARC. Methods The diagnosis of acetabular dysplasia was confirmed with X-ray examination, while imaging and HE staining were conducted to further evaluate the ARC thickness in each animal model. FISH was employed to verify miR-1-3p expression in the ARC and chondrocytes. The miR-1-3p target genes were predicted by a bioinformatics database. A dual-luciferase reporter assay was used to confirm the targeting relationship between miR-1-3p and SOX9. The gene expression of miR-1-3p, SOX9, RUNX2 and collagen type X was evaluated by qPCR analysis. The protein expression of SOX9, RUNX2 and collagen type X was detected by western blot analysis. The levels of SOX9, RUNX2, and collagen type X in the ARC were further assessed via immunohistochemistry analysis. Finally, Alizarin Red S staining was used to observe the mineralized nodules produced by the chondrocytes. Results We observed low expression of miR-1-3p in the ARC of animals with DDH. SOX9 is a miR-1-3p target gene. Using miR-1-3p silencing technology in vitro, we demonstrated significantly reduced chondrocyte-generated mineralized nodules compared to those of the control. We also confirmed that with miR-1-3p silencing, SOX9 expression was upregulated, whereas the expression of genes associated with endochondral osteogenesis such as RUNX2 and collagen type X was downregulated. To confirm the involvement of miR-1-3p silencing in abnormal ossification through SOX9, we also performed a rescue experiment in which SOX9 silencing restored the low expression of RUNX2 and collagen type X produced by downregulated miR-1-3p expression. Finally, the elevated SOX9 levels and reduced RUNX2 and collagen type X levels in the ARC of rabbits with DDH were also verified using immunohistochemistry, RT-PCR, and western blots. Conclusion The relatively low expression of miR-1-3p in the ARC may be the cause of abnormal endochondral ossification in the acetabular roof of animals with DDH.

Investigation of the effect of porous titanium cups on stress distribution in bone tissue (mathematical modeling)

Introduction. During arthroplasty in patients with altered anatomy and osteoporosis of the acetabulum, stable fixation of the acetabular component of the endoprosthesis is a very difficult task. There are studies on the bone tissue bonding to titanium, tantalum and ceramic coatings of endoprostheses. However, there are insufficient data on the influence of the strength characteristics of modern surfaces of the cups for hip endoprostheses on the distribution of mechanical stresses in the bone tissue around the implanted components. The purpose was to study on a mathematical model the changes in the stress-strain state of the endoprosthesis-bone system as a result of using porous tantalum cup. Materials and methods. A mathematical modeling has been carried out of the stress-strain state of the human hip joint in arthroplasty with porous cup. Du-ring the study, a defect in the acetabular roof filled with a bone implant fixed with two screws was simulated, as well as a defect in the acetabular floor filled with bone “chips”. Endoprosthesis cups were modeled in two versions: from solid titanium with a spray coating of porous titanium, and those entirely made of porous titanium. A distributed load of 540 N was applied to the sacrum. A load was applied between the iliac wing and the greater trochanter of the femur simulating the action of the gluteus medius — 1150 N and the gluteus minimus — 50 N. Results. The use of a cup with a coating of porous titanium in the normal state of the acetabulum leads to the occurrence of maximum stresses (15.9 MPa) in its posterior-upper part. Minimum stresses of 4.6 MPa are observed in the center of the acetabulum. The use of an endoprosthesis with porous titanium cup allows reducing the level of stresses in the bone tissue around the cup. If there is a defect in the acetabular roof, a hip endoprosthesis with porous titanium cup causes less stress than a solid titanium cup with coating of porous titanium. But on the graft, the stress level remains practically unchanged, regardless of the type of cup. The use of porous tantalum cup in the presence of a defect in the acetabular floor causes significantly less stress in the bone tissue around it, compared to an all-metal cup with coating. Conclusions. The cup of the hip endoprosthesis made of porous titanium causes significantly less stress in all control points of the model, compared to a cup made of solid titanium with coating of porous titanium, both with defects in the acetabular roof and floor, and without bone defects.

Cryoablation of osteoid osteoma with hip traction

Benign tumors of the acetabular roof are a therapeutic challenge. Percutaneous ablations avoid complicated surgery. These tumors are close to the cartilage and therefore there is a risk of damaging and causing chondropathy. We propose here the case of an osteoid osteoma treated by cryobablation associated with a hip traction with arthro-CT with warmed serum. Keywords: Cryoablation; Hip-traction; Osteoid osteoma; Mini-invasive; Interventional radiology

The acetabular roof reinforcement plate for the treatment of displaced acetabular fractures in the elderly: results in 59 patients

Introduction Open reduction and internal fixation is considered the gold standard of treatment for displaced acetabular fractures in younger patients. For elderly patients with osteoporotic bone quality, however, primary total hip arthroplasty (THA) with the advantage of immediate postoperative mobilization might be an option. The purpose of this study was to evaluate the clinical and radiological outcomes of surgical treatment of displaced osteoporotic acetabular fractures using the acetabular roof reinforcement plate (ARRP) combined with THA. Materials and methods Between 2009 and 2019, 84 patients were operated using the ARRP combined with THA. Inclusion criteria were displaced osteoporotic fractures of the acetabulum with or without previous hemi- or total hip arthroplasty, age above 65 years, and pre-injury ability to walk at least with use of a walking frame. Of the 84 patients, 59 could be followed up after 6 months clinically and radiographically. Forty-nine (83%) were primary fractures and 10 (17%) periprosthetic acetabular fractures. Results The mean age was 80.5 years (range 65–98 years). The average time from injury to surgery was 8.5 days (range 1–28). Mean time of surgery was 167 min (range 100–303 min). Immediate postoperative full weight bearing (FWB) was allowed for 51 patients (86%). At the 6-month follow-up, all 59 patients except one showed bony healing and incorporation of the ARRP. One case developed a non-union of the anterior column. No disruption, breakage or loosening of the ARRP was seen. Additional CT scans performed in 18 patients confirmed bony healing. Twenty-six patients (44%) had regained their pre-injury level of mobility. Complications requiring revision surgery occurred in 8 patients. Five of them were suffering from a prosthetic head dislocation, one from infection, one from hematoma and one from a heterotopic ossification. Conclusions The ARRP has proven to provide sufficient primary stability to allow for immediate FWB in most cases and represents a valuable option for the surgical management of displaced acetabular fractures in this challenging patient group.

MiR-1-3p Downregulation Delays Endochondral Ossification of the Acetabular Roof in DDH

Background: Developmental dysplasia of the hip (DDH) is a highly prevalent hip disease among children. However, its pathogenesis remains unclear. MiRNAs are important regulators in cartilage development. In previous study, miRNA high-throughput sequencing on an animal model of DDH showed a low level of miR-1-3p in the cartilage of acetabular roof (ARC), but its role in DDH pathogenesis was not addressed. Therefore, our aim was to investigate the effects of miR-1-3p in the ARC.Methods: The X-ray examination was performed to confirm acetabular dysplasia, MRI imaging and HE staining was conducted to further evaluate the ARC thickness in each animal model. The FISH was used to confirm the expression of miR-1-3p in the ARC and chondrocytes. The target gene of miR-1-3p was predicted by bioinformatics database. The dual-luciferase reporter gene assay was used to confirm the targeting relationship between miR-1-3p and SOX9. The gene expression of miR-1-3p, SOX9, RUNX2 and collagen type X by QPCR analysis. The relative proteins level was detected by western blot analysis. The level of SOX9, RUNX2 and collagen type X in the ARC through immunohistochemistry analysis. Alizarin Red S staining was used to observe the mineralized nodules produced by chondrocytes.Results: The low expression of miR-1-3p in the ARC of DDH. SOX9 is miR-1-3p target gene. Downregulation the expression of miR-1-3p in vitro and demonstrated significantly reduced chondrocytes generated mineralized nodules, as opposed to the control. We also confirmed that, with miR-1-3p silencing, SOX9 expression was upregulated, whereas expression of genes associated with endochondral osteogenesis RUNX2 and collagen type X were downregulated. To confirm the involvement of miR-1-3p silencing in abnormal ossification through SOX9, we also performed a rescue experiment where SOX9 silencing restored the low expression of RUNX2 and collagen type X, produced by miR-1-3p downregulation. Lastly, the elevated SOX9 levels and reduced RUNX2 and collagen type X levels in the ARC of DDH rabbits were also verified, using immunohistochemistry, RT-PCR, and western blot. Conclusion: The low expression of mir-1-3p in the ARC of DDH, which may be the cause of the acetabular roof abnormal endochondral ossification in DDH.

Central Acetabular Roof Defect- More than Just a Normal Variant?

Central acetabular defects are rare, and have been described using various terminologies (notches, fossae, pits). They are generally regarded as normal variants and often overlooked. This case series reviews five cases (age range 9-14 years) where presentation included hip pain and no alternative pathology was found. The defects tend to be bilateral but not symmetrical, and often just the side with the largest defect is symptomatic. The aetiology is unknown but there was no recollection of prior trauma. The literature suggests they are developmental in nature. The cases series highlights that these anatomical variants should not be entirely disregarded when imaging is reviewed.