Objective To evaluate the application effect of the problem based learning in clinical teaching of orthopedics. Methods We chose sixty five-year program students of Peking univ-ersity health science center as research object. All students were randomly divided into experimental and control groups, with thirty students in each group. Experimental group was given PBL teaching combined with lecture based learning (section-based learning, LBL), while the control group only received the LBL teaching. Two groups were given 8 hours of teaching experiments. After the end of the study, the teaching effect of the two groups was evaluated by the theory course and clinical skills. The questionnaire was distributed to the 2 groups. The scores of both experimental group students and control group students in theory courses and clinical skills were analyzed using SPSS 19.0 software using t-test and x2 test. Result The score of the experimental group was (53.7 ±3.2) in the knowl-edge-based grades exam, while the control group was (52.3±2.2), showing no obvious difference when compared to the control group's grades (P>0.05). The score of the experimental group was (24.0±1.5) in the hands-on technique grades exam, while the control group was (22.3±1.6). The difference in grades showed statistical significance (P<0.05). Feedback survey results showed that the experimental group's teaching satisfaction degree was also significantly higher than the control group, and the dif-ference was statistically significant (P<0.05). Conclusions The application of PBL in clinical teach-ing in orthopedic clinical teaching can improve students' learning interest and self-study ability, and helps to develop students' clinical thinking ability. But the role of PBL teaching in improving students' medical knowledge level is not obvious.

Objective To explore the localization diagnosis method of lumbar intervertebral foramen stenosis by multi-di-mensional MRI scans of lumbar nerve roots. Methods Twenty-one patients with lumbar intervertebral foramen stenosis were fol-lowed up from June 2006 to June 2011 postoperatively, 10 cases of male, 11 cases of female;36 to 65 years old, average 45.6 years. The medical history is six to thirty six months, an average of 9.4 years;5 cases have low back pain with unilateral leg pain and 16 cases showed unilateral leg pain only. The height of intervertebral space and foramen intervertebrale were measured on the X-rays of lumbar lateral position. Lumbar nerve roots MR imaging at the position of axial, coronal and sagittal scan were performed separately to the patients who were clinically suspected to suffer from lumbar intervertebral foramen stenosis. A definitive diagno-sis of the location of nerve root compression and structural changes surrounding the nerve root can be obtained. Surgical operation was performed to confirm the accuracy of the MRI imaging diagnosis. Results There were 9 cases of lumbar intervertebral fora-men stenosis caused by lumbar disc herniation. The other 12 cases are caused by zygapophyseal joint hyperplasia. All cases of lumbar intervertebral foramen stenosis located at the low back. By comparing MR images of lumbar intervertebral foramen stenosis with surgical procedure,the surgical observation of 21 patients completely coincided with the preoperative localization diagnosis, coincidence rate was 100%(21/21). After surgical treatment, 20 cases achieved a complete remission of leg pain and 1 case was not satisfactory. Conclusion MRI imaging at the position of axial, coronal and sagittal scan for lumbar nerve roots were useful to rigorous localization diagnosis of lumbar intervertebral foramen stenosis, and can provide accurate radiological evidence for sur-gery program.