The immunologic factors have been implicated in the pathogenesis of osteonecrosis. We aimed to investigate the potential role of immune regulatory cells in the development of osteonecrosis of femoral head (ONFH). Sixty-seven patients diagnosed with ONFH and fifty-eight age-, height-, and weight-matched healthy subjects were included in this retrospective study between September 2015 and September 2018. The flow cytometry was used to test the count, percentage, and ratio of T and B lymphocyte subsets in peripheral blood. The T and B lymphocyte levels were compared among different ARCO stages, CJFH types, and etiology groups. The total lymphocyte count, CD3⁺T cells, Ts cells (CD3⁺CD8⁺), B-1 cell count, and B-1 cells (CD5⁺CD19⁺) were significantly higher in the patients with ONFH than those in the control subjects. The percentage of T lymphocytes in the patients with ARCO IV stage was significantly smaller than that in the ONFH patients with ARCO II and III stages. The percentage of inhibitory T lymphocytes in patients with CJFH type L3 was significantly smaller than that in the patients with types L1 and L2. In terms of the different ONFH etiologies, the total lymphocyte count and Ts cells (CD3⁺CD8⁺) were significantly lower in the ONFH patients induced by excessive alcohol intake than those in the idiopathic ONFH patients. Our results seem to indicate that immune regulatory cells, such as T and B lymphocytes, play an important role in the pathogenesis of ONFH. The development and progression of ONFH may be associated with immune system imbalance.

Efficacy and safety of platelet-rich plasma (PRP) compared with control for preventing postoperative bleeding after total knee arthroplasty (TKA) is controversial. We performed a meta-analysis of randomized controlled trials (RCTs) to determine whether PRP might reduce blood loss and improve function following TKA. PubMed, Medline, Embase, Web of Science, and the Cochrane Library were searched to identify RCTs comparing PRP with control for patients undergoing unilateral TKA. The mean difference (MD) of total blood loss, hemoglobin (Hb) level, Hb drop, drain volume, range of motion (ROM), Western Ontario and McMaster Osteoarthritis Index (WOMAC) scores, length of hospital stay (LOS), and odds ratios of transfusion rate and postoperative complications in the PRP and control groups were pooled throughout the study. Relevant data were meta-analyzed using RevMan v5.3. Six RCTs involving 529 patients were included (208 PRP vs. 321 controls). The application of PRP in TKA had a significantly less calculated total blood loss (MD = −98.11; 95% confidence interval [CI]: −153.63 to −42.59, P = .0005) and lower Hb drop (MD = −0.34; 95% CI: −0.59 to −0.09, P = .008) than the control in the early postoperative period while decreasing the LOS (MD = −2.12; 95% CI: −3.47 to −0.76, P = .002). No significant differences were seen in drain volume, Hb level, transfusion rate, ROM, WOMAC scores, and complications between the 2 groups (P > .05). Our meta-analysis suggests that PRP appears to be effective in reducing postoperative blood loss and lowering Hb drop without increasing the risks of postoperative complications after TKA. However, owing to the variation of included studies, no firm conclusions can be drawn.

Osteonecrosis of the femoral head (ONFH) is a severe disease characterized by bone tissue necrosis due to vascular impairment, often leading to joint collapse and requiring surgical intervention. Extracellular vesicles (EVs) serve as crucial mediators of intercellular communication, influencing osteogenesis, angiogenesis, and immune regulation. This review summarizes the dual role of EVs in both the pathogenesis of ONFH and post-necrosis bone repair, highlighting the impact of various EV-mediated signaling pathways on bone regeneration and the potential crosstalk among these pathways. Additionally, EVs hold promise as diagnostic biomarkers or contrast agents to complement conventional imaging techniques for ONFH detection. By elucidating the role of EVs in osteonecrosis and addressing the current challenges, we aspire to establish a foundation for the timely identification and treatment of ONFH. The translational potential of this article: This review comprehensively discusses the role of EVs in ONFH, providing innovative and promising insights for its diagnosis and treatment, which also establishes a theoretical foundation for the future clinical application of EVs in ONFH.

Only a few studies exist that have assessed the efficacy of autologous osteochondral transplantation (AOT) treatment of osteonecrosis (ON) of the knee. The purpose of this study was to clarify the clinical and radiographic results of AOT performed on young patients with postcollapse ON of the knee. This retrospective study included 14 young patients (6 men, 8 women, mean age 34.71 ± 5.41 years) with stage III knee ON undergoing AOT surgery. Mean follow-up time was 87 ± 10.23 months. The postoperative clinical and radiological evaluations were based on Hospital for Special Surgery (HSS) scores and plain x-rays. Paired t tests were used for the statistical analysis by SPSS software. Preoperative HSS (mean 66.86 ± 7.49 points) was significantly improved at mean 7 years to a postoperative HSS (mean 87.36 ± 8.63 points) (P < 0.001). The postoperative rangeof motion (ROM; 125.71° ± 4.74°) was not significantly different from the preoperative ROM (126.86° ± 7.13°) (P = 0.626). There was no progression of collapse observed in any knees at the last follow-up. No knees required any reoperations during the follow-up period. Fourteen young patients with local ON of the knee were treated by AOT. No progression of bone collapse was seen and clinical improvement sustained at mean 7 years postsurgery. AOT seems to be a safe technique that can give long-term improvement and durability in young ON patients. However, large-sample and high-quality clinical trials are still needed in the future.

Knee osteoarthritis often leads to varus deformity, disrupting lower limb alignment and potentially causing ankle osteoarthritis. While total knee arthroplasty (TKA) can correct knee alignment and improve ankle alignment, the impact of different alignment strategies on the ankle remains unclear. This study investigates whether robot-assisted functional alignment (RA-FA) offers advantages over conventional mechanical alignment (CM-MA) in correcting ankle alignment, addressing the paucity of evidence on the impact of alignment strategies on distal joint biomechanics. A retrospective analysis was conducted on radiographic data from 202 patients with primary knee osteoarthritis who underwent TKA. Patients were divided into two groups based on the surgical approach: CM-MA group and RA-FA group, with 101 patients in each group. Using preoperative and postoperative full-length lower limb X-rays, multiple coronal radiographic parameters of the knee and ankle joints were measured. The correlation between knee and ankle alignments was assessed. Patients were further subgrouped based on the type of knee varus deformity, and differences in alignment correction between CM-MA and RA-FA within these subgroups were analyzed. Preoperatively, there were no significant differences in radiographic parameters of the knee and ankle between the two groups. Postoperatively, the RA-FA group showed superior correction in HKA and mLDFA compared to the CM-MA group. However, no statistically significant differences were observed between the two groups regarding ankle alignment correction. Subgroup analysis revealed that RA-FA was more effective in correcting knee alignment in specific subgroups. Nevertheless, even in these subgroups, RA-FA did not demonstrate a significant advantage over CM-MA in correcting ankle alignment. This study highlights the close relationship between knee and ankle alignments and confirms that TKA can improve ankle alignment. While RA-FA allows for more precise adjustments in femoral osteotomy and implant positioning, it does not significantly improve ankle alignment compared to CM-MA. Future studies should investigate the long-term effects of TKA on ankle alignment and evaluate whether other alignment strategies or different types of prostheses may influence the prognosis of the ankle or more distal joints such as the subtalar joint.