Purpose This study aimed to find the safe zone of two-dimensional (2D) fluoroscopy images in open reduction and internal fixation (ORIF) with long screws for Ogawa type I coracoid process fractures through three-dimensional (3D) simulation operations performed. Preliminary verification was carried out in cadaveric bone and clinical operations. Methods Shoulder computed tomography data of 100 adult participants were collected and reconstructed into 3D models. Virtual screws were created and placed to simulate long screw fixation. 3D models were adjusted to the Y-view of the scapula to be observed for 2D fluoroscopy, and quadrants were established with the centre of the glenoid of the shoulder as the origin. The positions of the screw tips were recorded, and the screw lengths (L1 and L2) and angles (α1, α2, β1, and β2) were measured. A scatter diagram was used to record the position of the screw tips and screw positions. Then the scatter diagram was switched to a thermal diagram to find the safe zone. Verification was carried out in both cadaveric bone and clinical operation. Results A fan-liked arc was obtained in the Y-view of the scapula of the 3D simulation. Most of the screw tips were located in the inferior posterior quadrant. According to the density of screw tips in the quadrant, the safe zone for screw placement was obtained. The screw lengths L1 and L2 were 53.44 ± 5.37 mm and 40.74 ± 6.02 mm, and the angles α1, α2, β1 and β2 were 30.43°±8.04°, 42.43°±6.44°, 65.14°±14.07° and − 1.7°±26.41°, respectively. Sex-dependent differences were found in L1, L2, and β1, P < 0.05. There was no statistical difference between the sexes in α1, α2, and β2, P > 0.05. Excellent results were obtained both in cadaveric bone and clinical operation based on this safe zone. Conclusions In this study, the safety zone of long screws in Ogawa type I coracoid process fracture was obtained, helps reduce iatrogenic injuries caused by screw penetration. For the best placement of screws, personalised simulated placement of screws was recommended before surgery.

Adipose derived stem cells (ADSCs) have the potential to attenuate osteoarthritis (OA); however, complications such as immune rejection and tumour formation limit their application. Exosomes (Exos)-mediated acellular therapy is promising in alleviating OA. This study aims to confirm whether ADSC-exos derived from infrapatellar fat pad (IPFP, ExosIPFP) are more suitable for ameliorating OA than ADSC-exos derived from subcutaneous fat (ScAT, ExoScAT) in vitro and in DMM models. Then, we investigated the regulatory mechanism by which the two kinds of Exos inhibit extracellular matrix (ECM) degradation in OA. ADSCs were successfully isolated and Exos were then obtained. ExosIPFP exhibited better attenuated effects on osteoarthritic chondrocytes in vitro and in vivo than ExoScAT. Small RNA sequencing was performed and the results shown that miR-99b-3p was upregulated in ExosIPFP. In vitro experiments confirmed that ADAMTS4 is a direct downstream target of miR-99b-3p. Over-expression miR-99b-3p in ExosScAT (ExosScAT-99b-3p) indicated that miR-99b-3p serves a positive role for OA treatment by inhibiting ADAMTS4 expression both in vitro and in vivo. In addition, hydrogel microparticles (HMPs) system was prepared by microfluidic technology, and confirmed the beneficial results for long-term therapeutic by continuous release of Exos. Take together, these results suggest that the therapeutic effects of ADSC-Exos may vary according to differential expression of miRNAs. Exosomal miR-99b-3p may act as a promising therapeutic strategy for OA, in addition, the injectable HMPs act as a sustained local drug release system, therefore representing great potential for treating OA and other diseases.