Obesity impairs revascularization and bone healing in a mouse model of osteonecrosis.

Osteonecrosis of the femoral head (ONFH) is a devastating bone disease that is caused by a disruption of blood supply leading to necrotic cell death. Clinically, it was found that obesity has a high prevalence with ONFH. However, it remains unclear how obesity may directly affect tissue regeneration and bone healing in osteonecrosis (ON). The purpose of this study is to investigate the effects of obesity and weight loss (WL) on ON healing. In this study, we induced obesity and WL in an established surgery-induced ON mouse model via feeding a high-fat diet (HFD) and altering the diet respectively. All mice received a surgical induction of ON of distal femoral epiphysis at the age of 12 weeks. HFD was switched to normal diet (ND) after ON surgery to induce WL. Mouse body weight was recorded weekly. Mouse body composition was scanned by DEXA (Dual-energy X-ray absorptiometry) right after sacrifice at the age of 16 weeks. The distal femoral bone samples were fixed and embedded for histology such as H&E, immunohistochemistry, and TRAP staining. In this study, we found that HFD-induced obesity impaired revascularization and bone remodeling showing decreased vessel areas and reduced osteoblast and osteoclast numbers. WL could rescue obesity-induced bone healing defects. Our study is the first to test the direct effects of obesity and WL on ON bone healing. We believe our work may provide new concepts for osteonecrosis treatment in obese patients.

Total Knee Arthroplasty in Human Immunodeficiency Virus Patients: A Literature Review.

Background: Total knee arthroplasty (TKA) has become a common surgical intervention for human immunodeficiency virus (HIV)-positive patients who develop osteonecrosis of the knee. This paper summarized existing literature regarding the outcomes of HIV-positive patients undergoing TKA in 4 subsections: (1) complications; (2) survivorship analyses; (3) patient-reported outcomes; and (4) infections. Methods: A review of PubMed was performed, searching for articles focused on HIV-positive patients undergoing TKA. There were 6 reports selected, containing 4765 HIV-positive patients, and data regarding the various domains was tabulated and analyzed. To ensure article quality, a methodology score and level of evidence were determined for selected studies. Results: Complication rates for HIV-positive patients were low, with a larger study reporting that 7.8% of HIV-positive patients developed a complication in comparison to 8% of HIV-negative patients. Survivorship analyses showed similar results, with a study reporting implant survivorship of 98% for HIV-positive and 99% for HIV-negative patients. There were no differences in patient-reported outcomes; HIV-positive patients improved from baseline with respect to the mean Knee Society objective and mean Knee Society functional scores, and the University of California, Los Angeles self-reported activity levels. The infection rate for HIV-positive patients was low, with a larger database study reporting that 0.6% of HIV-positive patients developed a wound infection in comparison to 0.4% of HIV-negative patients. Conclusions: A TKA is an effective treatment for HIV-positive patients who develop osteonecrosis of the knee. Results showed similar patient-reported outcomes, implant survivorships, revisions, and complication rates when compared to non-HIV patients.

Knee osteonecrosis after SARS-CoV-2 infection: a systematic case-based review.

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the virus responsible for coronavirus disease 2019 (COVID-19). Patients with COVID-19 manifested symptoms mainly related to the respiratory system, but also the musculoskeletal system can be involved. COVID-19 has been described as a possible cause of knee osteonecrosis (ON). A systematic review was performed to investigate the hypothetical correlation between COVID-19 and knee ON. Methods: Inclusion criteria were all articles reporting cases of knee ON after a diagnosis of SARS-CoV-2 infection. Considering that COVID-19 is an emerging disease, all levels of evidence studies were included. Results: Finally, two case series and three case reports were included. We extracted data regarding demographic and clinical characteristics, details of magnetic resonance imaging (MRI), use of corticosteroids (CCS), temporal correlation between ON and COVID-19, treatment of the lesion and its outcomes. A total of seven cases of post-COVID knee ON have been described. Knee pain arose on average 11 weeks after the diagnosis of COVID-19. All patients had knee MRI showing ON. CCS were used to treat COVID-19-related symptoms in four cases. Conservative treatment was successful in five patients. Conclusions: The correlation between COVID-19 and ON remains unclear. Probably post-COVID-19 ON has a multifactorial origin in which factors related to the patient, consequences of COVID-19 and CCS therapy add up to cause a reduction of blood supply and bone vitality until ON is triggered. A greater number of patients is needed to clarify the role of COVID-19 in the etiopathogenesis of knee ON.

Short-term outcomes after anatomic total shoulder arthroplasty in patients with osteoarthritis versus osteonecrosis.

BACKGROUND: The outcomes of anatomic total shoulder arthroplasty (TSA) for glenohumeral osteoarthritis (OA) have been extensively reported in the literature. However, there is a paucity of short-term outcomes data on perioperative and post-operative outcomes in patients receiving TSA for either glenoid or humeral head osteonecrosis (ON). We compared the short-term outcomes of TSA performed on patients who had glenohumeral OA and those who had ON. Specifically, we compared: (I) demographics; (II) length-of-stay (LOS); and (III) 30-day postoperative complication rates. METHODS: Data from the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) was used to select 7,066 patients with a diagnosis of glenohumeral OA or ON who underwent TSA between January 1st, 2008 and December 31st, 2015. Propensity score matching was performed based on age, sex, race, and body mass index (BMI) with a 3:1 ratio of OA to ON patients. As a result, 387 patients who had a primary diagnosis of OA were compared with 129 patients who had ON. Analyses addressed perioperative complications and hospital disposition factors-including LOS and 30-day post-operative complications-using bivariate and logistic regression models. RESULTS: Overall complication rates were low in both groups, at 6.1% and 5.4% for the ON and OA cohorts respectively. The ON cohort had more comorbidities, including higher Charlson/Devo and American Society of Anesthesiologists (ASA) scores (P<0.05). Hospital disposition factors were not statistically different between the 2 groups. While not statistically significant, the ON cohort had a longer average (21.1% longer, P>0.05), an increased risk for developing any complication [odds ratio (OR) =2.07; 95% confidence interval (CI), 0.94 to 4.57; P=0.07], and a 134% higher risk for developing a minor complication compared to the OA (OR =2.34; 95% CI, 1.01 to 5.42; P=0.047). CONCLUSIONS: Although the patient populations who develop ON or shoulder OA have differences, there are not statistically or clinically meaningful differences in the short-term outcomes after anatomic TSA. Future studies are required to examine if differences exist in the long-term follow-up between the two groups.

Zoledronic acid in pediatric metabolic bone disorders.

Zoledronic acid (ZA), a highly potent intravenous bisphosphonate (BP), has been increasingly used in children with primary and secondary osteoporosis due to its convenience of shorter infusion time and less frequent dosing compared to pamidronate. Many studies have also demonstrated beneficial effects of ZA in other conditions such as hypercalcemia of malignancy, fibrous dysplasia (FD), chemotherapy-related osteonecrosis (ON) and metastatic bone disease. This review summarizes pharmacologic properties, mechanism of action, dosing regimen, and therapeutic outcomes of ZA in a variety of metabolic bone disorders in children. Several potential novel uses of ZA are also discussed. Safety concerns and adverse effects are also highlighted.