Quantitative analysis of the mRNA expression levels of BCL2 and BAX genes in human osteoarthritis and normal articular cartilage: An investigation into their differential expression.

Osteoarthritis (OA) is primarily characterized by articular cartilage degeneration and chondrocyte loss. Although the role of apoptosis in cartilage pathobiology remains to be elucidated, the apoptotic B­cell CLL/lymphoma 2 (BCL2) gene family is considered to be involved in OA. The purpose of the present study was to quantitatively analyze the mRNA expression profiles of the BCL2­associated X protein (BAX) and BCL2 genes in human OA and in normal cartilage. Cartilage tissue samples were obtained from 78 patients undergoing total knee arthroplasty for OA (OA group) and orthopedic interventions for causes other than OA (control group). Total RNA was isolated from the cartilage tissue specimens and reverse transcribed into cDNA. A highly sensitive and specific reverse transcription quantitative polymerase chain reaction assay was developed for quantification of the mRNA levels of BAX and BCL2, using beta­2 microglobulin as an endogenous control for normalization purposes. Gene expression analysis was performed using the comparative Ct (2(­ΔΔCt)) method. The mRNA expression of BAX presented an increasing trend in the OA group compared with the control group, although without statistically significace (P=0.099). By contrast, the expression ratio of BCL2/BAX was found to be significantly decreased (2.76­fold) in the OA group compared with the normal cartilage control group (P=0.022). A notable 4.6­fold overexpression of median mRNA levels of BAX was also observed in patients with stage III OA compared with the control (P=0.034), while the BCL2/BAX ratio was markedly (2.5­fold) decreased (P=0.024). A marked positive correlation was observed between the mRNA levels of BAX and BCL2 in the control group (r(s)=0.728; P<0.001), which was also present in the OA group, although to a lesser degree (r(s)=0.532; P<0.001). These results further implicate apoptosis in the pathogenesis of OA, through molecular mechanisms, which include the aberrant expression of the BCL2 gene family. Further investigation may reveal novel prognostic biomarkers and potential targets for therapeutic interventions in the early stages of OA.

Treatment of stage III-A-1 and III-B-1 periprosthetic knee infection with two-stage exchange arthroplasty and articulating spacer.

The incidence of periprosthetic knee infection is generally low, but the economic impact is great. Treatment should take into account the acuteness of the infection, the overall immune/medical status of the patient, and the local factors at the site of the infection. The aim of this study was to evaluate the two-phase exchange arthroplasty with the use of antibiotic-impregnated articulating spacer, as an alternative treatment of chronic periprosthetic knee infection in patients with minimum systemic and no local compromising factors. Staphylococcus aureus was the most common pathogen followed by Staphylococcus epidermidis and Pseudomonas aeruginosa. Twenty-four patients were treated with this regiment. All of them returned to normal everyday activity and no infection recurrence was noted over a 2- to 10-year follow-up. Excellent long-term results can be achieved for patients staged as III-A-1 and III-B-1 according to the Musculoskeletal Infection Society staging system, when treated with the aforementioned protocol and intravenous antibiotics.

Late postoperative infection following spinal instrumentation: stainless steel versus titanium implants.

Late postoperative infection following instrumented spinal surgery is a clinical entity that has emerged in recent years. The extended surface of the spinal instrumentation in combination with hematogenous seeding or intraoperative inoculation is the main predisposing factor. In order to investigate the contribution of the instrumentation material (stainless steel versus titanium implants) and mechanical loosening, two groups of patients are presented. The first group includes 50 idiopathic scoliotic patients who were treated with first-generation posterior stainless steel spinal segmental multihook instrumentation [Texas Scottish Rite Hospital (TSRH) instrumentation system], and the second group includes 45 similar patients who were treated with newer titanium implants (MOSS MIAMI, XIA, and CD). Follow-up ranged from 3 to 13 years. Six patients from the first group and one patient from the second group presented with late infections 1 to 7 years postoperatively. Common intraoperative findings were excessive inflammatory tissue and some degree of instrumentation loosening and corrosion (stainless steel). Removal of instrumentation in combination with appropriate antibiotics was an effective treatment. Further study with long-term follow-up is necessary in order to understand the exact incidence and pathology of such infections.