ObjectiveTo explore the mechanism of extracorporeal shock wave (ESW) in treating osteogenic disorders and the ideal energy level. MethodsAfter success in marrow aspiration from patients' iliac crest, hMSCs were isolated by Percoll density gradient centrifugation and cultured in Dulbecco's modified Eagle's medium in a 5% CO2 and 37 ℃ incubator. Optimal ESW dose was determined by MTT of kinase-marked cytobiology. After hMSCs were exposed to ESW, their morphocytologic change, rate of adherence and doubling time were observed with IPCM. Enzyme cytochemistry reaction for the activity of alkaline phosphatase was also examined. ResultsESW of 5 kV and 100 times could increase cells' viability and proliferation (P<0.01), but higher than 7 kV would inhibit them. Rate of adherence of hMSCs in exposure group of passage 5 reached to 61.54%, which was significantly different from control group(P<0.05). Compared with control group, the MSCs' doubling time was short for 1.72 d (P<0.05). The curve of normal alkaline phosphatase activity of hMSCs was like type S, but ESW shortened its latent period, and promoted its peak time, which was significantly different from control group.ConclusionESW of 5 kV and 100 times can optimally promote the proliferation and activity of osteogen of hMSCs in vitro.

BACKGROUND:Due to the mismatch between the design of the proximal femoral nail antirotation Asian version(PFNA-Ⅱ)and Asian population,extrusion of the proximal femoral intertrochanteric nail may occur in the treatment of femoral intertrochanteric fractures.The influence of the protruding length on the curative effect of the operation needs to be further discussed. OBJECTIVE:To quantitatively measure the protruding length of the proximal trochanter of the femur with intramedullary nail after PFNA-Ⅱ,and to analyze the effect of protruding length on the efficacy of PFNA-Ⅱ in the treatment of femoral intertrochanteric fractures. METHODS:Totally 68 patients with femoral intertrochanteric fractures treated with PFNA-Ⅱ internal fixation in the First Affiliated Hospital of Anhui Medical University were selected.The extramedullary process of the proximal trochanter of the femur was quantitatively measured on the anterior and posterior X-ray films of the hip joint within 6 months after operation.According to the existence of extrusion of the proximal trochanter intramedullary nail,the patients were divided into protruding group and non-protruding group.The data of sex,height,fracture type,length and diameter of the intramedullary nail,the position of screw blade in the femoral neck and protruding length of proximal greater trochanter were collected.The postoperative curative effect was judged by visual analog scale pain score and hip joint Harris score at 6 months after operation.The influence of protruding proximal trochanter of the PFNA-Ⅱ intramedullary nail on the operative effect was observed. RESULTS AND CONCLUSION:(1)There were significant differences in sexual characteristics between the protruding group and the non-protruding group(P=0.001).(2)According to AO/OTA classification,there were no significant differences in fracture type between the protruding group and the non-protruding group(P=0.289).(3)There was no significant difference in the length and diameter of the intramedullary nail between the two groups(P=0.067,P=1.000).(4)There was no significant correlation between the height of all patients and the length of the intramedullary nail(P=0.510),but there was a significant correlation between height and protruding length(P=0.034).There was no significant correlation between screw blade position and protruding length(P=0.968).(5)Six months after operation,there was no significant difference in the hip Harris score(P=0.373),but the visual analog scale pain score was significantly higher in the protruding group than that in the non-protruding group(P=0.000).(6)The results suggest that nail extrusion often occurs in the proximal greater trochanter when PFNA-Ⅱ is used in the treatment of intertrochanteric fractures in Asians.When the nail extended into the proximal soft tissue of the greater trochanter,patients complained of proximal greater trochanteric pain and the visual analog scale score of proximal greater trochanter pain in the patient was significantly higher than that in the non-protruding group.To be more suitable for the Asian population,we suggest that the PFNA-Ⅱ should be improved to further shorten the proximal nail end to obtain better clinical results of femoral intertrochanteric fracture fixation.