[Arthroscopic suspension fixation with Endobutton in treatment of tibial insertion avulsion fractures of posterior cruciate ligament]

Objective

To investigate the effectiveness of arthroscopic suspension fixation with Endobutton in the treatment of tibial insertion avulsion fractures of posterior cruciate ligament (PCL).

Methods

A retrospective analysis was conducted on the clinical data of 52 patients (52 knees) with tibial insertion avulsion fractures of PCL, who were treated by arthroscopic suspension fixation with Endobutton between June 2017 and October 2022. There were 29 males and 23 females, with an average age of 40.6 years (range, 19-66 years). There were 24 cases of traffic accident injuries, 17 cases of sports injuries, and 11 cases of fall injuries. The time from injury to operation ranged from 6 to 19 days (mean, 13.3 days). According to the Meyers-McKeever classification, there were 30 cases of type Ⅱ and 22 cases of type Ⅲ fractures. All patients exhibited positive posterior drawer test results. Preoperative knee joint function was assessed with Lysholm score (21.3±6.7), International Knee Documentation Committee (IKDC) score (20.7±5.8), and visual analogue scale (VAS) score (5.3±0.7); and knee joint range of motion was (41.73±3.17)°. Based on preoperative CT three-dimensional reconstruction measurements, the longitudinal diameter of the avulsed bone fragment ranged from 13 to 25 mm (mean, 18.1 mm). Operation time and occurrence of complications were recorded, and postoperative imaging was used to assess fracture healing. Knee joint function and pain severity were evaluated using knee joint range of motion, Lysholm score, IKDC score, and VAS score.

Results

The operation time ranged from 46 to 81 minutes (mean, 56.2 minutes). All patients were followed up 12-28 months (mean, 20.1 months). The iatrogenic fractures of bone fragments occurred during operation in 4 cases; and knee effusion occurred in 2 cases and anterior knee pain in 1 case after operation. All incisions healed by first intention. Imaging evaluations at 3 months after operation showed the fracture healing and no internal fixation failure. All patients demonstrated good knee function and had returned to normal activities at 12 months after operation. At last follow-up, the knee joint range of motion was (133.44±4.17)°, Lysholm score 93.6±3.1, IKDC score 93.4±2.5, and VAS score 1.0±0.6, with significant differences compared to preoperative scores ( P<0.05).

Conclusion

Arthroscopic suspension fixation with Endobutton in the treatment of tibial insertion avulsion fractures of PCL is simple to operate, and the knee joint function recovers well.

[Preparation of Antibiotic-Loaded Copper-Doped Hydroxyapatite Microspheres and Evaluation of Their Antibacterial and Osteogenic Effect]

OBJECTIVE

To explore the preparation method of copper (Cu)-doped hydroxyapatite (HA) microspheres loaded with vancomycin (Van), and evaluate their antibacterial and osteogenic effects in vitro.

METHODS

The Cu doped HA microspheres (Cu-HA) with molar doping ratios of 1%, 5%, 10%, and 20% were prepared by hydrothermal synthesis. The microscopic morphology changes were observe with scanning electron microscope. X-ray diffractometer (XRD) was used to study the phase composition and analyze the crystallinity of the sample. Cu-HA with a molar doping ratio of 10% was selected for analysis of the elemental composition of the sample with energy dispersive X-ray spectroscopy (EDS), and was then coated with polydopamine (PDA) as the medium to prepare Cu-HA-PDA. XRD and Fourier infrared spectrometer were used to examine the coating effect of the sample. Van was load on Cu-HA-PDA to prepare Cu-HA-PDA-Van. HA, Cu-HA, HA-PDA, and Cu-HA-PDA-Van were added to α medium at 10 mg/mL to prepare different groups of extract solutions.The main components of the extract solutions were examined, and the Van concentration was checked. We examined the toxic effect of material extract solutions on osteogenic precursor cells and the proliferation and differentiation of bone marrow mesenchymal stem cells, and checked the expression of osteocalcin ( OCN), runt-related transcription factor 2 ( RUNX-2), and alkaline phosphatase ( ALP), the osteogenic related genes. Sterilized HA, Cu-HA, HA-PDA, Cu-HA-PDA, Cu-HA-DPA-Van microsphere materials were prepared, and the colony counting method was used to evaluate the antibacterial effect of the materials for Staphylococcus aureus.

RESULTS

Various types of Cu-doped HA (Cu-HA) were successfully synthesized. As the proportion of Cu increased, the morphology gradually changed from being strip or belt-shaped to a uniform spherical shape. Cu-HA of 10% molar doping ratio showed a clearly microspherical shape and a petal-like porous micro-nano morphology on the surface. EDS and XRD analyses showed that the main structure of the material was still made up of hydroxyapatite crystals and Cu was successfully doped with HA. The infrared spectrometer showed that the PDA was successfully coated on the surface of the material. Examination of the main components of the extract solution once again verified that the Cu element had successfully entered and replaced part of the Ca element in the HA. The 10 mg/mL Cu-HA-PDA-Van extract solution contained 0.27 mg/mL of Van. In vitro cell experiments and bone-formation-related gene testing showed that Cu-HA-Van had good biological activity and promoted bone differentiation. The minimum inhibitory concentration (MIC) of Cu-HA-PDA-Van microspheres was 16 μg/mL. Compared with Cu-HA, HA-PDA and pure HA, Cu-HA-Van microspheres had significant and long-lasting antibacterial effects.

CONCLUSION

Cu element was used to control the microscopic morphology of HA, and the Cu-HA-PDA-Van microspheres prepared by successfully coating of PDA and loading of Van had good antibacterial properties and biological activity.

[Changes in expressions of sRNA SpR19 and its potential target GroEL in Streptococcus mutans strains with different cariogenicity cultured under different pH conditions]

OBJECTIVE

To investigate the changes in the expression level of sRNA SpR19 and its potential target protein GroEL in clinical isolates of Streptococcus mutans with different cariogenicity exposed to different pH conditions and explore the possibility of using these molecules as biomarkers for assessing the cariogenicity of the bacteria.

METHODS

The total RNAs were extracted from the clinical isolates of Streptococcus mutans with high (strain 17) and low cariogenicity (strain 5) for high-throughput sequencing for profiling of the differentially expressed sRNAs. The candidate sRNA, SpR19, was selected for further study on the basis of bioinformatics analysis considering the role of its potential target in the cariogenic process. The differential expression levels of SpR19 in the strains exposed to both pH5.5 and pH7 culture conditions were verified by quantitative real-time PCR. The expression of the potential target of SpR19, GroEL, was also investigated at both the protein and mRNA level using Western blotting and quantitative real-time PCR.

RESULTS

Bioinformatic analysis suggested multiple potential target sites of SpR19 both in GroEL mRNA and in the upstream and downstream inter-genic regions. Under different pH conditions, the highly cariogenic strain 17 expressed consistently low levels of SpR19 as compared with the strain 5 with a low cariogenicity; GroEL showed a reverse expression pattern in the 2 strains. An inverse correlation was found between the expressions of SpR19 and GroEL.

CONCLUSION

The highly cariogenic strain 17 expressed low levels of SpR19 and high levels of GroEL in both acidic and neutral culture conditions. SpR19 may negatively regulate the cariogenicity of Streptococcus mutants by targeting at GroEL.