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Abstract Background Antimicrobial agents are administered via intramedullary antibiotic perfusion (iMAP)/intrasoft tissue antibiotic perfusion (iSAP) to infected lesions to control osteoarticular and soft tissue infections. Continuous local antibiotic perfusion (CLAP) has been reported to be useful. This study aimed to investigate the outcomes of DAIR combined with CLAP for chronic PJI after total knee arthroplasty performed at our hospital. Subjects and methods Six patients (male; one case, female; five cases, mean age 79.5 years (70–94)) underwent CLAP for chronic PJI after TKA at our hospital between July 2020 and June 2022. They were followable for at least one year after surgery. Seven months (17–219), with a mean follow-up of 24.3 months (12–36). In addition to direct debridement and insert exchange, systemic antimicrobial treatment, and CLAP with gentamicin were performed using NPWT. We investigated the organisms causing the inflammation, the duration of iMAP/iSAP implantation, the maximum daily dose of GM, the maximum GM blood concentration, and the presence or absence of GM-induced adverse events. Result Two of six patients had a recurrence of infection at five weeks and five months after initial CLAP and required repeat CLAP treatment, but all patients could preserve their components. The organisms responsible for the flare-ups were MSSA in three cases: ESBL-producing E. coli, mixed MSSA and streptococcal infection, Klebsiella pneumonia in one case each, and unknown pathogens in one case. CLAP therapy for all patients was administered eight times in 6 cases: iMAP, mean: 10.0 days (5–16); iSAP, mean: 19.3 days (15–28); GM dose, mean: 162.5 mg/day (80–240); and GM blood concentration, mean: 1.4 µg/mL (0.2-5.0). Adverse events included one case of reversible acute kidney injury during CLAP in a patient with recurrent infection. Summary DAIR with CLAP for chronic post-TKA infection can be a useful treatment option to preserve components and allow the infection to subside, provided the implant is not markedly loosened.

Objectives: Chronic obstructive pulmonary disease (COPD) is a risk factor for osteoporosis. Nevertheless, much remains unclear regarding the bone metabolism dynamics associated with COPD. The present study focuses on the associations between the COPD severity and serum bone metabolism biomarkers. Methods: We enrolled 40 patients who visited the orthopedics departments at our institutions and underwent dual-energy X-ray absorptiometry between September 2015 and December 2017. Only male osteoporosis patients over 45 years of age were included, and 5 patients were excluded due to disease or use of internal medicines affecting bone metabolism. All subjects underwent lung function testing, spine radiography, and blood tests. We measured percent forced expiratory volume in 1 second (%FEV1), which reflects COPD severity, and we examined the relationships between %FEV1 and serum levels of bone metabolism biomarkers. Results: All subjects were diagnosed with osteoporosis based on T-scores. %FEV1 correlated with body weight, body mass index (BMI), and Z-score/T-scores. %FEV1 moderately correlated with serum levels of alkaline phosphatase (ALP), procollagen type 1 N-terminal propeptide (P1NP), and tartrate-resistant acid phosphatase 5b in the partial correlation analysis adjusted for BMI or T-score in the lumbar vertebrae. We performed a hierarchical multiple regression analysis to identify that serum ALP and P1NP were the independent explanatory variables to %FEV1 independent of other factors. Conclusions: The data suggest that the COPD severity in middle-aged and older men with osteoporosis associates with decreased bone formation. COPD patients may exhibit bone metabolism dynamics characterized by low bone turnover with osteogenesis dysfunction as COPD becomes severe.

This study aimed to clarify whether novel cotton-like composite made of β-tricalcium phosphate (β-TCP) and poly(Dl-lactide-co-glycolide) (PDLGA) has a different effect on in vivo bone regeneration after bone defect than that of granular β-TCP. Five male Beagle dogs served as subjects. Cortical and medullary bone defect as non-through holes were made at the diaphysis of the bilateral femurs. One side was implanted with β-TCP/PDLGA (β-TCP/PDLGA group) and the other side was implanted with granular β-TCP (β-TCP group). At 4 weeks after implantation, we found no significant differences in the percentages of newly formed bone area and fibrous tissue area in the bone defect between the two groups. The β-TCP/PDLGA group showed more uniform filling on the surface and earlier disappearance of the material in the medullary region, and there were fewer inflammatory cells and osteoclasts in the bone defect in the β-TCP/PDLGA group. In conclusion, β-TCP/PDLGA performs better at filling the bone defect uniformly and disappears earlier at the cortical and medullary regions while causing less inflammation and bone resorption. Although bone formation activity of the β-TCP/PDLGA group in the cortical region was lower, the newly formed bone volume in bone defect of the β-TCP/PDLGA group was equal to that of the β-TCP group.

Calcium balance is important in bone homeostasis. The transient receptor potential vanilloid (TRPV) channel is a nonselective cation channel permeable to calcium and is activated by various physiological and pharmacological stimuli. TRPV1 and TRPV4, in particular, have important roles in intracellular Ca2+ signaling and extracellular calcium homeostasis in bone cells. TRPV1 and TRPV4 separately mediate osteoclast and osteoblast differentiation, and deficiency in any of these channels leads to increased bone mass. However, it remains unknown whether bone mass increases in the absence of both TRPV1 and TRPV4. In this study, we used TRPV1 and TRPV4 double knockout (DKO) mice to evaluate their bone mass in vivo, and osteoclast and osteoblast differentiation in vitro. Our results showed that DKO mice and wild type (WT) mice had no significant difference in body weight and femur length. However, the results of dual-energy X-ray absorption, microcomputed tomography, and bone histomorphometry clearly showed that DKO mice had higher bone mass than WT mice. Furthermore, DKO mice had less multinucleated osteoclasts and had lower bone resorption. In addition, the results of cell culture using flushed bone marrow from mouse femurs and tibias showed that osteoclast differentiation was suppressed, whereas osteoblast differentiation was promoted in DKO mice. In conclusion, our results suggest that the increase in bone mass in DKO mice was induced not only by the suppression of osteoclast differentiation and activity but also by the augmentation of osteoblast differentiation and activity. Our findings reveal that both the single deficiency of TRPVs and the concurrent deficiency of TRPVs result in an increase in bone mass. Furthermore, our data showed that DKO mice and single KO mice had varying approaches to osteoclast and osteoblast differentiation in vitro, and therefore, it is important to conduct further studies on TRPVs regarding the increase in bone mass to explore not only individual but also a combination of TRPVs.

Transient osteoporosis of the hip (TOH) is a rare disorder characterized by acute severe coxalgia and temporary osteopenia in the proximal femur. Although most cases were unilateral or staged bilateral TOH, some authors reported that the pregnant patients simultaneously had TOH in their bilateral hips. However, there has been no report of simultaneous bilateral TOH in the patient without pregnancy. A 25-year-old Japanese woman without pregnancy had acute simultaneous bilateral hip pain. Plain X-ray of the bilateral hips did not show a periarticular osteopenia. However, magnetic resonance image obtained one week after the onset demonstrated increased T2-weighted signal intensity and decreased T1-weighted signal intensity in the bilateral femoral heads. She was treated conservatively, and follow-up magnetic resonance image at seven weeks after the onset returned to normal bone marrow signal intensity. Her bilateral coxalgia subsided gradually. At one year after the onset, she had no sign of symptomatic flair. Our experience with this case indicates that recognizing the possibility of simultaneous bilateral TOH is important unless the patient is pregnant, and magnetic resonance image is predictable test to make a diagnosis of TOH, even in the absence of abnormal finding on plain X-ray.