Late intraprosthetic dislocation of a monoblock dual-mobility cup cemented into a well-fixed cementless acetabular shell. A case report.

Intraprosthetic dislocation (IPD) is a specific implant-related complication of dual mobility (DM) implants, which is defined as a dissociation of polyethylene (PE) liner from the femoral head. We report a unique case of  late IPD of a monoblock DM cup cemented into a well-fixed cementless acetabular shell for recurrent dislocation of total hip arthroplasty (THA). A 77-year-old woman was admitted to our department for acute right hip pain, functional impairment and inability to bear weight without any trauma. Three years earlier, she underwent revision THA for recurrent dislocation with a monoblock DM cup cemented into a well-fixed cementless acetabular shell according to the "double-socket" technique. Three months after that revision the patient experienced an anterior THA dislocation, which was managed by closed reduction under sedation in the emergency room. No additional episodes of prosthesis instability occurred. Upon admission, radiographic evaluation showed  right THA dislocation. X-rays performed  after closed reduction revealed eccentric positioning of the head inside the cup, and a direct contact between the metal head and the cup was revealed by subsequent CT scan, confirming the suspicion of IPD. The patient underwent revision surgery, during which the PE liner was found lodged within the cup in a subluxated position, disassembled from the inner head. Both the acetabular cup and modular femoral stem proved well-fixed and impossible to remove, therefore they were retained. The explanted DM components were replaced with new ones of the same size and, thanks to the femoral neck's modular nature, it was substituted with a longer one, which resulted in improved stability against intraoperative stress maneuvers. The postoperative course was uncomplicated. At 1-year follow-up, the patient had a good functional recovery.

Correlation between hip osteoarthritis and proximal femoral fracture site: could it be protective for intracapsular neck fractures? A retrospective study on 320 cases.

Proximal femoral fractures affect elderly people, showing high morbidity and mortality incidence resulting in a major economic burden on national healthcare systems. Understanding the causes of these injuries is of paramount importance to prevent the serious consequences of these fractures. INTRODUCTION: Hip osteoarthritis and proximal femoral fractures mainly affect elderly patients. Several authors, in their studies, tried to document a correlation between these conditions, but the results are conflicting. The aim of this study was to evaluate the relationship between hip osteoarthritis and the fracture site. Secondly, to evaluate if the grade of osteoarthritis could influence the fracture pattern. METHODS: A retrospective study on 320 patients admitted for hip fracture between June 2015 and December 2016 was carried on. Radiographic images were evaluated, assessing the type of fracture, presence and grade of osteoarthritis according to Kellgren-Lawrence and Tönnis classifications, and their correlations. RESULTS: Osteoarthritis was found to affect the fracture site showing a higher prevalence among subjects with extracapsular than those with intracapsular fractures (p < 0.00001). Patients with radiographic signs of arthritis had mainly trochanteric fracture. Conversely, patients without arthritis more frequently presented a femoral neck fracture. This correlation was even more significant as the severity of the OA increased. CONCLUSIONS: Results support the hypothesis that hip osteoarthritis could represent a protective factor for intracapsular fractures and a risk factor for trochanteric ones. The severity of arthritis is also associated with the fracture pattern.

Conditioned media from human osteoarthritic synovium induces inflammation in a synoviocyte cell line.

AIM: Osteoarthritis (OA) is a whole joint pathology involving cartilage, synovial membrane, meniscus, subchondral bone, and infrapatellar fat pad (IFP). Synovitis has been widely documented in OA suggesting its important role in pathogenesis. The aim of this study was to investigate the role of different joint tissues in promoting synovitis. MATERIALS AND METHODS: Conditioned media (CM) from cartilage, synovial membrane, meniscus, and IFP were generated from tissues of five patients undergoing total knee replacement and used to stimulate a human fibroblast-like synoviocytes cell line (K4IM). Cytokines, chemokines, and metalloproteases release was analyzed in all CM by Bio-Plex Assay and sulfated glycosaminoglycan (GAG) content by dimethylmethylene blue assay. Gene expression of several markers was evaluated by real-time PCR in K4IM cells stimulated with the CM obtained from joint tissues. RESULTS: CM from all tissues produced high levels of IL-6, IL-8, and CCL2. CCL21, MMP-3, and -13 levels were detected in all CM except IFP. MMP-10 was present only in CM of cartilage and synovial tissues. IL-1ß, IL-15, TNF-α, CCL5, and CCL19 were undetectable. However, only K4IM cells stimulated by the CM from OA synovium showed an increase of IL-6, CXCL-8, CCL21, MMP10, and IL-1ß expression. CONCLUSION: Our study showed that K4IM might be a suitable in vitro model for evaluating different cellular pathways in OA studies. Importantly, we demonstrated that in OA, all joint tissues might be involved in the progression of synovitis with a predominant role of synovial membrane itself compared to the other joint tissues.