Aims: Continuous local antibiotic perfusion (CLAP) has recently attracted attention as a new drug delivery system for orthopaedic infections. CLAP is a direct continuous infusion of high-concentration gentamicin (1,200 μg/ml) into the bone marrow. As it is a new system, its influence on the bone marrow is unknown. This study aimed to examine the effects of high-concentration antibiotics on human bone tissue-derived cells.Methods: Cells were isolated from the bone tissue grafts collected from six patients using the Reamer-Irrigator-Aspirator system, and exposed to different gentamicin concentrations. Live cells rate, apoptosis rate, alkaline phosphatase (ALP) activity, expression of osteoblast-related genes, mineralization potential, and restoration of cell viability and ALP activity were examined by in vitro studies.Results: The live cells rate (the ratio of total number of cells in the well plate to the absorbance-measured number of live cells) was significantly decreased at ≥ 500 μg/ml of gentamicin on day 14; apoptosis rate was significantly increased at ≥ 750 μg/ml, and ALP activity was significantly decreased at ≥ 750 μg/ml. Real-time reverse transcription-polymerase chain reaction results showed no significant decrease in the ALP and activating transcription factor 4 transcript levels at ≥ 1,000 μg/ml on day 7. Mineralization potential was significantly decreased at all concentrations. Restoration of cell viability was significantly decreased at 750 and 1,000 μg/ml on day 21 and at 500 μg/ml on day 28, and ALP activity was significantly decreased at 500 μg/ml on day 28.Conclusion: Our findings suggest that the exposure concentration and duration of antibiotic administration during CLAP could affect cell functions. However, further in vivo studies are needed to determine the optimal dose in a clinical setting.Cite this article: Bone Joint Res 2024;13(3):91–100.

The Masquelet technique is a relatively new method for large bone defect treatment. In this technique, grafted bone tissue is used, and after the cement is removed, the induced membrane (IM; that form around the cement spacers placed in the bone defect region) is thought to play an important role in promoting bone formation. On the other hand, low-intensity pulsed ultrasound (LIPUS) is known to promote fracture healing and angiogenesis through mechanical stimulation. This study aimed to investigate the in vitro effects of LIPUS on the osteogenic differentiation of human induced membrane-derived cells (IMCs). Seven patients who had been treated using the Masquelet technique were enrolled. The IM was harvested during the second stage of the technique. IMCs were isolated, cultured in growth medium, and then divided into two groups: (1) control group, IMCs cultured in osteogenic medium without LIPUS, and (2) LIPUS group, IMCs cultured in osteogenic medium with LIPUS treatment. Adherent cells from the IM samples were harvested after the first passage and evaluated for cell surface protein expression using immunostaining. A cell proliferation assay was used to count the number of IMCs using a hemocytometer. Osteogenic differentiation capability was assessed using an alkaline phosphatase (ALP) activity assay, Alizarin Red S staining, and real-time reverse transcription-polymerase chain reaction. Cell surface antigen profiling revealed that the IMCs contained cells positive for the mesenchymal stem cell-related markers CD73, CD90, and CD105. No significant difference in cell numbers was found between the control and LIPUS groups. The ALP activity of IMCs in the LIPUS group was significantly higher than that in the control group on days 7 and 14. Alizarin red S staining intensity was significantly higher in the LIPUS group than in the control group on day 21. Runx2 and VEGF expression was significantly upregulated on days 7 and 14, respectively, compared with levels in the control group. We demonstrated the significant effect of LIPUS on the osteogenic differentiation of human IMCs. This study indicates that LIPUS can be used as an additional tool for the enhancement of the healing process of the Masquelet technique.

Purpose: The aim of this study was to investigate whether the day of starting oral intake affects the clinical course of patients with aspiration pneumonia. Patients and methods: We conducted a retrospective cohort study of 392 patients who were hospitalized for aspiration pneumonia but tolerated oral intake. Patients were divided into two groups according to the day of starting oral intake: Monday to Friday (midweek group) and Saturday or Sunday (weekend group). Underlying diseases, severity of pneumonia, time to oral intake, hospital duration, discontinuation of oral intake, and death during hospitalization were compared between the groups. Multivariate analysis was performed using hospital duration and discontinuation of oral intake due to aspiration as the dependent variables. Results: The cohort comprised 244 men and 148 women with a mean age of 79.3 ± 13.1 years. The weekend (n = 98) and midweek (n = 294) groups exhibited similar age, sex, and underlying diseases. There were no significant differences in pneumonia-related factors, such as CURB-65 score, A-DROP score, extent of shadow on chest radiograph, incidence of bacteremia, and ventilator use. The weekend group exhibited a significantly shorter time to oral intake and hospital duration, as well as a significantly lower incidence of discontinuation of oral intake than the midweek group. Multivariate analysis revealed that starting oral intake on the weekend was independently associated with a lower incidence of discontinuation of oral intake due to aspiration.
Conclusion: The weekend group exhibited a shorter total hospital duration and a lower incidence of discontinuation of oral intake due to aspiration.

In this study, we examined the proliferation capability and osteogenic and chondrogenic differentiation potential of non-hypertrophic nonunion cells (NHNCs), and the effect of Escherichia coli-derived BMP-2 (E-BMP-2) on them. We enrolled five patients with non-hypertrophic nonunion. NHNCs isolated from nonunion tissue sampled during surgery were cultured, passaged, counted every 14 days, and analyzed. NHNCs were homogenous fibroblastic adherent cells and long-lived through at least 10 passages, with a slight decline. The cells were consistently positive for mesenchymal stem cell-related markers CD73 and CD105, and negative for the hematopoietic markers CD14 and CD45. NHNCs could differentiate into osteoblast lineage cells; however, they did not have strong calcification or sufficient chondrogenic differentiation capability. E-BMP-2 did not affect the proliferative capability of the cells but improved their osteogenic differentiation capability by increasing alkaline phosphatase activity and upregulating the gene expression of osterix, bone sialoprotein, and osteocalcin. E-BMP-2 enhanced their chondrogenic differentiation capability by upregulating the gene expression of aggrecan and collagen type II. We showed, for the first time, that NHNCs have the capacity to differentiate into osteoblast-lineage cells, although the chondrogenic differentiation potential was poor. Local application of E-BMP-2 with preservation of nonunion tissue is a potential treatment option for non-hypertrophic nonunion.

症例1は80歳，女性．嘔吐で受診し，CTでS状結腸と近接した左卵巣に腫大と内部にガス貯留を認めた．注腸で造影剤の腸管外漏出を認め，S状結腸憩室炎による左卵管卵巣膿瘍と診断し，待機的にS状結腸切除，一期的吻合を行った．症例2は65歳，女性．下腹部痛で婦人科を受診した．骨盤腹膜炎の診断で保存加療を行ったが改善せず，CTで腹腔内遊離ガスとS状結腸憩室，右卵巣にガス貯留を伴う膿瘍形成を認めたため，S状結腸憩室炎による結腸穿孔および右卵管卵巣膿瘍と診断し，緊急でHartmann手術と子宮全摘，両側付属器切除術を行った．症例3は76歳，女性．腹痛で受診した．CTで腹腔内遊離ガスとS状結腸と近接した左卵巣に腫大と内部にガス貯留を認め，S状結腸憩室炎による結腸穿孔および左卵管卵巣膿瘍と診断し，緊急でHartmann手術を行った．大腸憩室炎による卵管卵巣膿瘍は稀な病態であり，本邦報告例に自験例を加えた10症例についての検討を加えて報告する．