MARS MRI Characteristics of Adverse Local Tissue Reactions in Taper Corrosion of Metal-On-Polyethylene THA Differ From Metal-On-Metal THA.

BACKGROUND: Metal artifact reduction sequence (MARS) magnetic resonance imaging (MRI) has been recommended as a cross-sectional imaging modality in clinical evaluation of adverse local tissue reactions (ALTRs) in metal-on-metal (MoM) patients and metal-on-polyethylene (MoP) patients with taper corrosion. The aim of the study was to compare MARS MRI characteristics of ALTR in MoM total hip arthroplasty (THA) with ALTR in MoP THA with modular taper corrosion. METHODS: A total of 197 patients with ALTR were evaluated: 86 patients with MoM THA; 37 MoP patients with head-neck taper corrosion; and 74 MoP patients with neck-stem dual taper corrosion. MARS MRI scans were evaluated to identify location, size, type of ALTR (I-III), and associated ALTR synovitis (cystic, solid, and mixed). RESULTS: MARS MRI characteristics of ALTR were significantly different between the MoM and MoP groups (P = .017). The MoP group demonstrated the highest proportion of thick-walled cystic masses type II (56.7% in head-neck taper corrosion MoP and 46.5% in dual taper corrosion MoP vs 28.7% in MoM), whereas the MoM group had the highest proportion of thin-walled cystic masses type I. MoM implants (96.8%) were significantly more likely to have ALTR in multiple locations compared with both MoP groups (P = .001). CONCLUSION: This study demonstrates that MARS MRI characteristics of ALTR differ by bearing type with a significantly higher percentage of mixed type and solid type ALTR in the taper corrosion MoP THA compared with MoM THA. This information provides clinically useful information in evaluation of symptomatic MoP and MoM THA patients for ALTRs.

Outcome of Re-Revision Surgery for Adverse Local Tissue Reaction in Metal-on-Polyethylene and Metal-on-Metal Total Hip Arthroplasty.

BACKGROUND: Adverse local tissue reactions (ALTRs), initially described as a complication of metal-on-metal (MoM) total hip arthroplasty (THA), have also become an important risk factor for implant failure requiring revision surgery in metal-on-polyethylene (MoP) THA due to modular taper corrosion. This study aims to report early complication rates and outcomes as well as potential risk factors for a re-revision. METHODS: A total of 252 consecutive THA patients who underwent revision for ALTR were reviewed. There were 40 patients (16%) who underwent a second revision: (1) 26 MoP patients with modular taper corrosion and (2) 14 MoM patients. Patient demographics as well as clinical information were analyzed. Binary logistic regression was used to test for associations between re-revision surgery and clinical parameters. RESULTS: The overall complication rate following initial revision for ALTR was 21%. Sixteen percent of these revision patients required a re-revision. The most common indication for re-revision was dislocation (45%). The complication rate was 35% following a re-revision which included dislocation (36%), infection (36%), fracture (14%), and implant loosening (14%). The rate of patients requiring a third revision was 23% with the most common indications being dislocation (33%) and infection (33%) (P = .032). CONCLUSION: High rate of early complications (35%) and third revisions (23%) were observed following re-revision of symptomatic ALTR patients with those requiring re-revision associated with extensive intraoperative tissue necrosis. These findings provide clinically useful information that may assist surgeons in clinical decision making and preoperative counseling of both MoM and MoP patients undergoing re-revision surgery for ALTR.

Preoperative Opioid Use Negatively Affects Patient-reported Outcomes After Primary Total Hip Arthroplasty.

BACKGROUND: Opioid use is a public health crisis in the United States and an area of increased focus in orthopaedic surgery. The aim of this study is to investigate whether preoperative opioid use had any effect on patient-reported outcome measures (PROMs) before and after total hip arthroplasty (THA). METHODS: A total of 389 patients with THA with both preoperative and postoperative PROMs were reviewed: (1) 76 patients with preoperative opioid use (24%) and (2) 237 patients without preoperative opioid use (76%). Patient demographics and clinical information including opioid use, length of stay, and implant information. RESULTS: Preoperative opioid users were more likely to stay in the hospital longer (P = 0.004) and be discharged to a rehabilitation facility (P = 0.038). Postoperatively, the Physical Function Short Form 10a (P = 0.021) and Patient-Reported Outcomes Measurement Information System Global-10 (P < 0.001 physical, P = 0.001, mental) were significantly lower in the preoperative opioid users. Within groups, both nonusers and preoperative opioid users saw improvements after THA in Hip Disability and Osteoarthritis Outcome Score-Physical Function Short Form (P < 0.001), Short Form 10a (P < 0.001), and Patient-Reported Outcomes Measurement Information System Global-10 (P < 0.001, physical and P = 0.008, mental). DISCUSSION: Although all patients reported improvements after THA regardless of preoperative opioid use, preoperative opioid users undergoing THA had significantly lower patient-reported outcome scores, longer hospital stays, and a more likely discharge to rehabilitation.

Angiocrine factors from Akt-activated endothelial cells balance self-renewal and differentiation of haematopoietic stem cells.

Endothelial cells establish an instructive vascular niche that reconstitutes haematopoietic stem and progenitor cells (HSPCs) through release of specific paracrine growth factors, known as angiocrine factors. However, the mechanism by which endothelial cells balance the rate of proliferation and lineage-specific differentiation of HSPCs is unknown. Here, we demonstrate that Akt activation in endothelial cells, through recruitment of mTOR, but not the FoxO pathway, upregulates specific angiocrine factors that support expansion of CD34(-)Flt3(-) KLS HSPCs with long-term haematopoietic stem cell (LT-HSC) repopulation capacity. Conversely, co-activation of Akt-stimulated endothelial cells with p42/44 MAPK shifts the balance towards maintenance and differentiation of the HSPCs. Selective activation of Akt1 in the endothelial cells of adult mice increased the number of colony forming units in the spleen and CD34(-)Flt3(-) KLS HSPCs with LT-HSC activity in the bone marrow, accelerating haematopoietic recovery. Therefore, the activation state of endothelial cells modulates reconstitution of HSPCs through the modulation of angiocrine factors, with Akt-mTOR-activated endothelial cells supporting the self-renewal of LT-HSCs and expansion of HSPCs, whereas MAPK co-activation favours maintenance and lineage-specific differentiation of HSPCs.