The harmfulness of occult intra-articular fracture has drawn attention since the last decade. Due to the application and popularization of CT, MRI and 3D reconstruction techniques, the injury mechanisms and characteristics of occult intra-articular fractures have been gradually understood. Nevertheless, it is often reported that an intra-articular fracture was overlooked in diagnosis and treatment so that the residual intra-articular displacement affected the recovery of joint function and led to such complications as traumatic arthritis in a long term, seriously impairing the function of the affected limb. The author summarized the key points in imaging examinations for occult intra-articular fractures, the rules and characteristics of some of the fractures and the distinction between them and their variant anatomical structures, hoping to help orthopedic surgeons improve their understanding, diagnosis and treatment of these fractures.

Continual discoveries and inventions are the only way for the development of natural science. However, there has been controversy about either of which is more important than the other one. From the perspective of natural science, the present article compares the promoting effects of scientific discoveries versus technical inventions on natural science from four aspects: the definition and relationship of discoveries and inventions, the scientific discoveries and technical inventions view of Nobel Prize, the process from discoveries to inventions in theory, and the ownership of discovery right and invention right. This study focuses on the characteristics of subjects on 334 Nobel Prizes in the field of natural science from 1901 to 2019. Further, most awards are given for the scientific discoveries in Physiology or Medicine field, which account for 90.9%. This outcome indicates that scientific discovery as the source of science is more favored by the natural science community, which is in line with the general goal of the "Thirteenth Five-Year Plan" of the National Natural Science Foundation of China. We hope that the majority of natural science researchers, during the process of promoting the development of natural science in China, should not only pay attention to the original discoveries of the "source of water", but also discover some things with spirit of questioning. The researchers should have the courage to break the inherent thinking and have the courage and patience to to discover the fundamental theory.

BACKGROUND:As a lightweight metal with mechanical properties similar to natural bone, a natural ionic presence with significant functional roles in biological systems, and in vivo degradation via corrosion in the electrolytic environment of the body, magnesium (Mg)-based implants have the potential to serve as biocompatible, osteoconductive, degradable implants for load-bearing applications. On the other hand, Mg, as a critical mediator of cellular growth and activities regulation, is the second most abundant intracellular cation where it plays an important role in enzyme function and trans-membrane ion transport.
OBJECTIVE:To retrospectively summarize the application progress, physiological role and mechanism of Mg, and to review its regulation of bone metabolism.
METHODS:Papers addressing application, physiological and bone metabolism regulation of Mg published in core periodicals were reviewed. Studies in which Mg were used as an assistance materials, or articles regarding cellphysiology in which Mg were not the main research object were excluded. Literatures concerning the regulation of bone turnover by Mg were given special attention.
RESULTS AND CONCLUSION:Mg al oys are cytocompatible materials with adjustable mechanical and corrosion properties and show their potential as biodegradable implant materials. Moreover, Mg is abundantly distributed among the body and essential for maintaining physiological function of the cells. Mg deficiency has been associated with a number of clinical disorders including osteoporosis. But it remains to be determined what specific biochemical process is activated by Mg2+to regulate cellular activity and bone turnover. Further investigations of the precise mechanism are valuable to the clinical application of Mg.

BACKGROUND: The femoral neck fracture is a common skeletal injury, with high mortality and disability rate. Nonunion and avascular necrosis in femoral head are the main problems in treatment of femoral neck fracture. Up to now, the guidelines for its management continue to be unsolved and are stil evolving.
OBJECTIVE:This study aims to summarize the incidence of two femoral neck fracture complications, as wel as the advance in prevention and treatment. This work can help to better understand the mechanism of non-union and avascular necrosis, and to choose the optimal management of this fracture.
METHODS:Papers in terms of femoral neck fracture published in core periodicals were reviewed. Studies which are not directly related to femoral neck fracture or articles regarding poly-trauma were excluded. Literatures concerning non-union and avascular necrosis after femoral neck fracture were preferred.
RESULTS AND CONCLUSION:A total of 241 articles were screened out, and those were mainly published in the last five to ten years. 182 unrelated papers were excluded, and 59 papers were included in the analysis. The femoral neck fracture has a high incidence. Nowadays, there are a variety of treatments for this fracture, but the stability and healing result of fractures depend on many factors, such as age, classification of fracture, general condition of patient, and accompanying diseases. Up to now, the choice of management is stil controversial. Imaging representation and patient’s age are not the main factors for the selection of treatment. Hence, a comprehensive assessment of the risk factors that influence fracture healing is necessary for surgeons to choose an optimal treatment of this fracture. Femoral neck fractures, therefore, represent an enormous socio-economic and medical problem and chal enge surgeons to find the cheapest and most effective way to treat them. Internal fixation of the fracture in combination with the use of osteo-inductive materials may be a new way to further improve the treatment effects of femoral neck fracture.

[Objective]To study the injury mechanism of sacral plexus resulting from sacral zone-Ⅱ fractures of lateral compression.[Method]Six short-term(in a year) embalmed pelves were obtained from anatomic department of Hebei Medical University with preserving sacral plexus and resecting pubic symphysis,the models of sacral zone-Ⅱ fractures of lateral compression were produced.Quantitative analysis for fracture displacement was carried out to observe the characteristic and the mechanism of sacral plexus injury.Sacral plexus were replaced by proportional diameter silica gel pips fulled with contrast medium,experimental procedure was repeated under X-ray.The experimental data were analyzed by SPSS10.0 statistic software and the result was obtained.[Result]In lateral compression type sacral canal was closed and its volume reduced and small free fracture segment resulted in sacral plexus nerves oppressed,especially of L_5,Sland S_2.At the same time,the more overlapping of pubic symphsis,the more serious of compression.[Conclusion]Sacral plexus is conncted with the wall of pelvic cavity and fixed.Zone-Ⅱ sacral fracture is likely to damage sacral plexus.In lateral compression type of sacral fracture nerve injury is mainly compression injury which position is in nerve canal,especially of S_1,S_2.And L_5 can be crushed in fracture interspace to be damaged seriously.

ObjectiveTo observe the effect of continuous passive motion (CPM) on postoperative functional rehabilitation in lower limb.Methods267 patients operated in lower limb were separated to CPM group (162 cases) and control group (105 cases). Patients of the CPM group used CPM device at early period post operation, and cases of the control group received instruction to exercise by themselves. The efficacy of two methods was evaluated.ResultsThe knee activity of affected extremity of CPM group at 10 day and 1 month was better than that of control group, as well as the rate of swelling extinction of affected extremity (P<0.05～0.01).ConclusionIt is propitious to functional rehabilitation of patients operated in lower limb that using CPM early post operation.

Objective To investigate the technique and clinical effects of pedicle screw fixation in treatment of unstable Hangman' s fractures in comparison with the conservative managements. Methods From January 1999 to July 2005, 36 patients with unstable Hangman' s fractures were treated in our department. Based on Levine- Edwards classification, 15 of them were treated with skull traction, and others with internal fixation with posterior pedicle screws (C2,3 fusion in 10 cases and C2- 4 fusion in 11 cases). After a posterior midline incision and clear exposure of posterior structure, the C2 screw was inserted through the center of the posterior aspect of lateral mass, inclining usually 20? to 30? towards the head of the transverse plane and 25? to 35? inwards to the medial incline of the sagittal plane. For C3,C4 screw insertion, the drilling was parallel to the joint plane of the relevant vertebra and inclined 35? to 40? outwards to the medial incline of the sagittal plane. The whole procedure was performed under the monitoring of C- arm screen for safety and accuracy. Results A mean follow- up time was 18 months (5 to 28 months). 6 cases treated by skull traction lost their anatomic reduction. Of the 21 cases treated by the pedicle screw fixation, 2 had loosened internal fixation but 19 experienced no screw loosening and their fractures were cured entirely without limited function of the cervical vertebra. Conclusions In treatment of unstable Hangman' s fractures, C2,3 or C2- 4 pedicle screw fixation is an effective method to achieve rigid reduction and early rehabilitation. However, there is no remarkable difference between C2,3 fusion and C2- 4 fusion

[Objective]To study the imageologic characteristic of pelvic arterial anastomosis and the method of ultraselection arterial embolism for pelvic fracture with hemorrhage.[Method]From 1999.1-2005.6,60 patients were undergone pelvic arteriography.The patient ages ranged from 21 to 52 years of age(mean,34.5),and 42 were male,18 were female.Measure the types and number of pelvic arterial anastomosis.[Result]The types and number of pelvic arterial anastomosis were observed by pelvic arteriography as follows: the lumbar artery with iliolumbal artery 100%;the iliolumbal artery with deep iliac circumflex artery 83.33%;the obturator artery with inferior epigastric artery(or external iliac artery) 36.67%;the lateral sacral artery with coccygeal artery 100%;the inferior gluteal artery with internal pudendal artery 26.67%;the inferior gluteal artery with deep femoral artery 56.67%;the superior gluteal artery with inferior gluteal artery 61.67%.[Conclusion]For pelvic fracture whith hemorrahge,the best treatment of the pelvic arterial disruption is embolization of injured arteries and their anastomosis.

Objective To determine safe zones at the medial and lateral calcaneus for percutaneous pin placement in Chinese patients.Methods Fourteen cadaveric specimens of normal Chinese adult foot and ankle joints were dissected in this study.At the medial calcaneus of each foot, the most medial and posteroinferior point, the most inferior medial malleolus and the navicular tuberosity were identified and labeled as points A, B and C respectively.The medial calcaneal nerve, the most posterior branch of the lateral plantar nerve, the lateral plantar nerve, the medial plantar nerve, the posterior tibial artery, the lateral plantar artery and the medial plantar artery were carefully dissected and identified.A relative safe zone at the medial calcaneus was marked off according to where the neurovascular structures crossed lines AB and AC.At the lateral calcaneus, the most lateral and posteroinferior point and the inferior lateral malleolus were identified and labeled as points D and E respectively.The lateral calcaneal nerve, the sural nerve and the trunk of the small saphenous vein were carefully dissected and identified.A relative safe zone at the lateral calcaneus was marked off in the same way as that at the medial calcaneus.Results At the medial calcaneus, the medial calcaneal nerve, the most posterior branch of the lateral plantar nerve, the lateral plantar nerve, the medial plantar nerve and the posterior tibial artery crossed line AB respectively at posteroinferiorly 22%, 50%,56%, 64% and 58% of the line.The medial calcaneal nerve, the most posterior branch of the lateral plantar nerve, the lateral plantar nerve, the medial plantar nerve, the lateral plantar artery and the medial plantar artery crossed line AC respectively at posteroinferiorly 14%, 39%, 49%, 63%, 41% and 57% of the line.At the lateral calcaneus, the lateral calcaneal nerve, the sural nerve and the trunk of the small saphenous vein crossed line DE respectively at posteroinferiorly 19%, 65% and 61% of the line.Conclusions At the medial calcaneus, the circular region posterior to the 1/2 of line AB and to the 1/3 of line AC may be considered as a relative safe zone for percutaneous pin placement; at the lateral calcaneus, the region posterior to the perpendicular at the midpoint of line DE may be considered as a relative safe zone for percutaneous pin placement.