[Objective]To design a method of in vitro preparation and seperation for metallic wear particles around joint prosthesis and evaluate its feasibility in medical experiments.[Method]Ti-6Al-4V and Co-Gr-Mo alloys were used to make two friction jars respectirely. National inventive patent applied number 03142073.7.Lots of quadrate blocks made of the same materials are put into the jars respectively,which were then.lubri cated by man-made body fluid and vibrated on a bottle shaker.After 21 days the fluid was harvested and centrifuged to get the produced wear particles.The collected particles were studied by using element trace analysis,laser countersizer and scanning electron microscopy.The J774.A1 macrophages cultured together with these particles for 24 hours were observed under inverted phase contrast microscopy and transmission electron microscopy.[Result]A got great amounts of metallic particles with 1?m diameter coned beproduce using this method.The aver age diameter of titanium alloys(Dv90) is 1.011 and that of Co-Gr-Mo is 1.010.Particle size distribution had good consistency in different materials.Under scanning electron microscopy ,the particles had irregular shapes just like those got from revision operations.The particles taken into the J774.A1 macrophages could be seen under inverted p hase contrast microscopy and transmission electron microscopy.[Conclusion]This method is good enough to producl lots of metallic wear particles mosth like those around total joint prosthesis and can be used in further in vivo and in vitro studies about joint prosthesis loosening.

Objective To evaluate the clinical efficacy of total hip arthroplasty (THA) with no femoral shortening oste?otomy for unilateral CroweⅣ developmental dysplasia of hip. Methods From October 2007 to January 2010, 32 patients with CroweⅣdevelopmental dysplasia of hip in one side underwent THA, including 20 females and 12 males, with an average age of 49.4 ± 9.7 years (range, 23-60 years). There were 15 cases as normal and 17 as mild developmental dysplasia of hip in the other side. The THA were performed with requisite soft tissue release and direct leverage using an elevator but with no femoral shorten?ing osteotomy. The patients' satisfaction, Harris hip score, bilateral leg?length discrepancy and pelvic obliquity was used to assess the clinical results. Results All of patient were followed up for 1-6 years, average 4.0 ± 1.5 years. No loosening or failure of component occurred by the end of follow?up. The Harris hip score was improved from preoperative 36.5±10.3 (20-63) to 89.8± 4.9 (80-97), and the excellent and good rate was 100% (excellent 16 cases, good 16 cases). The satisfactory rate was 93.8%(30/32). The leg?length discrepancy of the bilateral sides and the pelvic obliquity was corrected gradually and the gait returns to normal. Nine cases have valgus knee after THA and 4 cases of them felt uncomfortable after long?distance walk. Femoral nerve injury occurred in 2 cases. All of cases recovered after 1 and 3 months respectively. No infection and dislocation oc?curred. Conclusion THA with no femoral shortening osteotomy can achieve good clinical results in patients with unilateral CroweⅣdevelopmental dysplasia of hip. The discrepancy of leg?length will be diminished with the correction for pelvic obliquity.

Abnormal mechanical loading is the main risk factor for the development of osteoarthritis (OA), and it can lead to collagen degradation, glycosaminoglycan loss and chondrocyte apoptosis, as well as damage to articular cartilage and subchondral bone. However, due to the lack of understanding in chondrocytes mechanotransduction pathway and invalid method of cartilage repair and regeneration, there is an urgent need for understanding chondrocytes mechanotransduction pathway and mechanism of cartilage damage induced by mechanical loading. In this review, how chondrocytes sense and transmit mechanical signals from cell membrane to cecullar mechanosensors is introduced in detail, and the role of chondrocytes mechanotransduction in OA development is discussed with emphasis.

Objective To study the relationship of the tibial plateau subchondral trabecular bone (STB) microstructure and the cartilage degeneration with the lower limb alignment based on individual trabecula segmentation (ITS) and histology analysis in knee osteoarthritis (OA). Methods Hip-knee-ankle (HKA) angles were measured on the full-length lower extremity films of patients before total knee arthroplasty (TKA). The tibial plateau excised from the TKA were collected for micro-CT scanning and ITS analysis. The cartilage degeneration was evaluated by histology. The relationship between the HKA angle and the changes in microstructural parameters of STB and cartilage degeneration were analyzed. ResultsThe plate, rod and axial bone trabecular volume fraction (BV/TV, pBV/TV, pBV/TV), ratio of trabecular plate versus rod (P/R), plate trabecular number density (pTb.N), plate trabecular thickness (pTb.Th), trabecular plate surface area (pTb.S), trabecular rod length (rTb.L), and plate-plate and plate-rod junction density (P-P Junc.D, P-R Junc.D) of the subchondral bone of the tibial plateau were significantly related to the cartilage degeneration OARSI score and the HKA angle. The greater the deviation of the lower limb alignment, the greater the number of subchondral trabeculae, the thicker the trabeculae, the greater the bone mass, the stronger the connectivity, especially the plate trabeculae on the affected side of tibial plateau, and the higher the OARSI score of cartilage degeneration. Conclusions Abnormal lower limb alignment may cause abnormal microstructure of the plate and rod STB of the tibial plateau by changing the stress distribution of the knee, especially the significant increase and thickening of the plate trabecular and axial trabecular bone, which may be an important risk factor that further aggravates the degeneration of articular cartilage and the progress of OA. Therefore, lower limb alignment correction with surgical intervention and improving STB with bone metabolism agents may efficiently contribute to preventing cartilage damage and mitigate OA progression.

Objective To investigate the difference of matrix stiffness in different regions of tibial plateau in osteoarthritis (OA) and its effects on morphology of the cartilage and mitochondria. Methods The tibial plateau cartilage specimens of OA were obtained for nanoindentation test, transmission electron microscopy and histological analysis. The stiffness of cartilage matrix in different regions of OA tibial plateau was detected by nano-indentation. The morphology of cartilage mitochondria in different regions was observed by transmission electron microscopy, and the changes of mitochondrial plane area, shape and ridge volume density were quantitatively analyzed. Cartilage injury in different regions of OA tibial plateau was observed by histological staining. Results The cartilage of OA tibial plateau showed regional heterogeneity, and the cartilage and mitochondria on medial side of varus knee OA were more severe, and the matrix stiffness was higher. The OA scores were positively correlated with matrix stiffness. There was also a significant correlation between OA scores and mitochondrial morphology: the higher OA scores, the larger and rounder mitochondrial plane area, and the lower cristae volume density. Conclusions The differences of tibial plateau revealed the correlation between cartilage matrix stiffness, OA scores and mitochondrial morphological parameters. The increased cartilage matrix stiffness may be the main cause of chondrocyte mitochondrial injury, and further aggravate the progression of OA.