Objective To develop a knee joint impact device to produce animal model of subchondral bone micro-fracture in rabbits.Methods A knee joint impact device was designed. 12 New Zealand rabbits were divided into group A (n=6) and Group B (n=6). In the group A, 6 patellar-femoral joints of the 6 rabbits were impacted (1.74 kg from height of 30 cm). In the group B, 6 femoral condyles of the 6 rabbits were impacted (1.14 kg from height of 28 cm). All the rabbits were evaluated with X-ray and MRI post injury. The femora of all the rabbits were observed with HE staining. Results No fracture line was found in all the animals with X-rays. The MRI of the 6 knee joints in the group A showed low signal intensities on T1 weighted, T2 weighted and fat suppression images. Histopathology demonstrated integrated cartilage and sunchondral bone plate, micro-fractures of cancellous and bleeding in marrow. The MRI of the 5 knee joints in the group B showed low signal intensities on T1 weighted images and high signal intensities on T2 weighted and fat suppression images. Histopathology demonstrated integrated cartilage and sunchondral bone plate, micro-fractures of cancellous and bleeding in marrow. No disorder was found with MRI and histology in the contral sides. Conclusion The impact device of the knee joint can produce controllable and reproducible subchondral bone micro-fracture in rabbits.

Objective To observe the interference and influence of sample hemolysis on biochemical test results and to make cor-responding countermeasures based on the research results .Methods There were 58 cases of people who underwent physical exami-nation in the hospital .They were selected as study objects .Sample of venous blood was 5 mL in fasting .After natural coagulation and centrifugation ,K+ ,Na+ in blood were measured ,followed by the TP ,CK ,CK-MB ,AST ,ALB ,TG ,HDL ,LDH ,HBDH and other biochemical indexes .Then all indexes mentioned above were detected again after the sample hemolysis of serum ,and analysis results were compared between them .Results Of biochemical indicators detected before and after the determination of hemolysis , there were of statistical significance in the differences in K + ,Na+ ,TP ,CK ,CK-MB ,AST ,LDH and HBDH(P<0 .05);but there were no significant differences in biochemical indicators like ALB ,HDL and TG(P>0 .05) .Through regression analysis ,biochemi-cal indicators such as K + ,Na+ ,TP ,CK ,CK-MB ,AST ,LDH and HBDH were found to be related to hemolysis .Conclusion Sample hemolysis has certain influences on the results of biochemical test in terms of K + ,Na+ ,TP ,CK ,CK-MB ,AST ,LDH and HBDH , which is of certain application value with the proofreading of serum Hb concentration .

ObjectiveTo investigate the characteristics of knee stiffness and the results of rehabilitation after the fractures of distal femur （DF）, tibial plateau （TP） or patella （PF）. Methods70 cases with knee stiffness after DF, TP or PF were analyzed retrospectively. ResultsNo significant difference was observed in passive range of motion (PROM) among three groups (F=1.671，P=0.196) before rehabilitation. The differences were significantly different (F=19.264, P=0.000) 8 weeks after rehabilitation. Further LSD analysis revealed that there was significant difference between DF and TP (P=0.000) as well as DF and PF (P=0.000), but no significant difference was observed between TP and PF (P=0.114). ConclusionThe outcome of rehabilitation is associated with the locations of fracture, and the distal femoral fractures is the worst.