Role of CD36 in central nervous system diseases

CD36 is a highly glycosylated integral membrane protein that belongs to the scavenger receptor class B family and regulates the pathological progress of metabolic diseases.CD36 was recently found to be widely expressed in various cell types in the nervous system,including endothelial cells,pericytes,astrocytes,and microglia.CD36 mediates a number of regulatory processes,such as endothelial dysfunction,oxidative stress,mitochondrial dysfunction,and inflammatory responses,which are involved in many central nervous system diseases,such as stroke,Alzheimer’s disease,Parkinson’s disease,and spinal cord injury.CD36 antagonists can suppress CD36 expression or prevent CD36 binding to its ligand,thereby achieving inhibition of CD36-mediated pathways or functions.Here,we reviewed the mechanisms of action of CD36 antagonists,such as Salvianolic acid B,tanshinone IIA,curcumin,sulfosuccinimidyl oleate,antioxidants,and small-molecule compounds.Moreover,we predicted the structures of binding sites between CD36 and antagonists.These sites can provide targets for more efficient and safer CD36 antagonists for the treatment of central nervous system diseases.

Single-cell RNA sequencing in orthopedic research

Although previous RNA sequencing methods have been widely used in orthopedic research and have provided ideas for therapeutic strategies,the specific mechanisms of some orthopedic disorders,including osteoarthritis,lumbar disc herniation,rheumatoid arthritis,fractures,tendon injuries,spinal cord injury,heterotopic ossification,and osteosarcoma,require further elucidation.The emergence of the single-cell RNA sequencing(sc RNA-seq)technique has introduced a new era of research on these topics,as this method provides information regarding cellular heterogeneity,new cell subtypes,functions of novel subclusters,potential molecular mechanisms,cell-fate transitions,and cell-cell interactions that are involved in the development of orthopedic diseases.Here,we summarize the cell subpopulations,genes,and underlying mechanisms involved in the development of orthopedic diseases identified by sc RNA-seq,improving our understanding of the pathology of these diseases and providing new insights into therapeutic approaches.

Erratum to: PHOSPHO1 Serves as a Key Metabolism-Related Biomarker in the Tumorigenesis of Diffuse Large B-cell Lymphoma

Theoriginal vversion of this article unfortunately contained a mistakee.The institution number of the author Huang-ming CAO was incorrect.The corrected one is Huang-ming CAO^(3).

Cyclops syndrome following anterior cruciate ligament reconstruction: Can relapse occur after surgery?

Symptomatic cyclops lesions are complications that can be seen at rates of up to approximately 10%after anterior cruciate ligament reconstruction.However,recurrent cyclops lesions have rarely been documented.There are case rare series in the literature regarding the treatment of recurrent cyclops lesion.Future large studies are needed to investigate factors contributing to the development of cyclops lesions and syndrome and treatment options.

Perioperative rh-endostatin with chemotherapy improves the survival of conventional osteosarcoma patients: a prospective non-randomized controlled study

Objective: Anti-angiogenic drugs are an emerging treatment option against malignant tumors. The aim of this study was to determine whether the addition of perioperative rh-endostatin to chemotherapy could improve the probability of distant metastasis-free survival(DMFS) and overall survival(OS) in patients newly diagnosed with non-metastatic conventional osteosarcoma.Methods: This was a controlled non-randomized clinical study that included 388 patients without clinically detectable metastatic disease enrolled from January 2008 to April 2012. The control treatment group had 272 patients; 180 were male and 92, female,with a median age of 17 years. The treatment group had 58 patients; 36 were male and 22, female, with a median age of 16 years.The control group received preoperative chemotherapy followed by surgery and postoperative chemotherapy. The treatment group received 4 cycles of rh-endostatin perioperatively in addition to chemotherapy as per the control group. Patients were followed up from 6-101 months with a median follow-up period of 50.2 months.Results: The 5-year DMFS of the control group(61%) was significantly lower than that of the rh-endostatin group(79%)(P = 0.013). The 5-year OS of the control group(74%) was significantly lower than that of the rh-endostatin treatment group(87%)(P = 0.029). No difference in adverse drug reactions was found between these 2 groups.Conclusions: The addition of perioperative rh-endostatin to chemotherapy could significantly improve the DMFS and OS of patients with non-metastatic osteosarcoma.

The role of GPCRs in bone diseases and dysfunctions

The superfamily of G protein-coupled receptors (GPCRs) contains immense structural and functional diversity and mediates a myriad of biological processes upon activation by various extracellular signals.Critical roles of GPCRs have been established in bone development,remodeling,and disease.Multiple human GPCR mutations impair bone development or metabolism,resulting in osteopathologies.Here we summarize the disease phenotypes and dysfunctions caused by GPCR gene mutations in humans as well as by deletion in animals.To date,92 receptors (5 glutamate family,67 rhodopsin family,5 adhesion,4 frizzled/taste2 family,5 secretin family,and 6 other 7TM receptors) have been associated with bone diseases and dysfunctions (36 in humans and 72 in animals).By analyzing data from these 92 GPCRs,we found that mutation or deletion of different individual GPCRs could induce similar bone diseases or dysfunctions,and the same individual GPCR mutation or deletion could induce different bone diseases or dysfunctions in different populations or animal models.Data from human diseases or dysfunctions identified 19 genes whose mutation was associated with human BMD:9 genes each for human height and osteoporosis;4 genes each for human osteoarthritis (OA) and fracture risk;and 2 genes each for adolescent idiopathic scoliosis (AIS),periodontitis,osteosarcoma growth,and tooth development.Reports from gene knockout animals found 40 GPCRs whose deficiency reduced bone mass,while deficiency of 22 GPCRs increased bone mass and BMD;deficiency of 8 GPCRs reduced body length,while 5 mice had reduced femur size upon GPCR deletion.Furthermore,deficiency in 6 GPCRs induced osteoporosis;4 induced osteoarthritis;3 delayed fracture healing;3 reduced arthritis severity;and reduced bone strength,increased bone strength,and increased cortical thickness were each observed in 2 GPCR-deficiency models.The ever-expanding number of GPCR mutation-associated diseases warrants accelerated molecular analysis,population studies,and investigation of phenotype correlation with SNPs to elucidate GPCR function in human diseases.

CCNO mutation as a cause of primary ciliary dyskinesia:A case report

BACKGROUND Primary ciliary dyskinesia(PCD)is an uncommon and genetically diverse condition.According to reports,most patients had more than 50 visits before being diagnosed with PCD,and the age at diagnosis was mostly in preschool,with an average age of about(10.9±14.4)years old.CCNO is a pathogenic gene that regulates the cell cycle,and its mutation is linked to the uncommon human genetic disorder PCD.Although the prevalence of the CCNO mutation is regarded to be exceptionally low,new reports of this mutation have increased in comparison to prior ones.PCD patients with CCNO are rare,and the incidence rate is no more than 2%in whole PCD patients.CASE SUMMARY Here,we report a case of a young Chinese woman diagnosed with PCD,who was found to carry the CCNO gene by whole exon gene sequencing.In this case,a young non-smoking Chinese female exhibiting recurrent cough and sputum at birth.Chest computed tomography(CT)showed bronchiectasis with infection,and sinus CT showed chronic sinusitis.However,the patient had no visceral transposition and no history of infertility.Under electron microscope,it was found that cilia were short and reduced in number,and no power arm of cilia was observed.Whole exon sequencing analysis of the genome of the patient showed that the patient carried CCNO pathogenic gene,exon c.303C>A nonsense mutation and c.248_252dup frameshift mutation.Her clinical symptoms and CT images were improved after two months of treatment with aerosol inhalation and oral azithromycin.CONCLUSION The results showed that CCNO is an important cause of PCD.More mutant genes that may contribute to genetically diverse disorders like PCD have been discovered as sequencing technology has advanced.Furthermore,the increase of genetic information makes it easier to diagnose uncommon diseases in clinical practice.

A clinical and mechanistic study of topical bingpian-induced analgesia

OBJECTIVE Bingpian is an almost pure chemical with a chemical composition of(+)-borneol and has been historically used as a topical analgesic in traditional Chinese medicine for millennia.However,the clinical efficacy of topical bingpian lacks stringent evidence-based clinical studies and the underlying molecular mechanisms are unclear.This study verified the analgesic efficacy of topical bingpian in humans,and elucidated the underling mechanisms in animal models of pain.METHODS The analgesic efficacy of topical bingpian was examined in a randomized,double-blind,placebo-controlled clinical study at the Shanghai Changzheng Hospital.Capsaicin,formalin,CFA or thermal caused pain/hyperalgesia were established in different mouse models,and bingpian-induced analgesia and the underlying mechanisms were studied in these models.The molecular targets of bingpian were examined by calcium imaging,patch-clamp recording and enzymatic activity assay in mouse sensory neurons or transfected HEK 293 cells.RESULTS(1)Topical application of bingpian leads to significantly greater pain relief than placebo does in a randomized,double-blind,placebo-controlled clinical study involving 122 patients with postoperative pain.(2)TRPM8 channel is the most sensitive molecular target of bingpian and mediates topical bingpian-induced analgesia in mice.(3)A downstream glutamatergic mechanism in the spinal cord contributes to topical bingpian-induced analgesia.(4)Bingpian shows mechanistic differences and advantages as a topical analgesic when compared with menthol.

PHOSPHO1 Serves as a Key Metabolism-Related Biomarker in the Tumorigenesis of Diffuse Large B-cell Lymphoma

Objective:Diffuse large B-cell lymphoma(DLBCL)is an aggressive type of non-Hodgkin lymphoma.Due to its genetic heterogeneity and abnormal metabolism,many DLBCL patients have a poor prognosis.This study investigated the key metabolism-related genes and potential mechanisms.Methods:Differentially expressed genes,differentially expressed transcription factors(TFs),and differentially expressed metabolism-related genes(DEMRGs)of glucose and lipid metabolic processes were identified using the edgeR package.Key DEMRGs were screened by Lasso regression,and a prediction model was constructed.The cell type identification by estimating relative subsets of RNA transcripts algorithm was utilized to assess the fraction of immune cells,and Gene Set Enrichment Analysis was used to determine immune-related pathways.A regulatory network was constructed with significant co-expression interactions among TFs,DEMRGs,immune cells/pathways,and hallmark pathways.Results:A total of 1551 DEMRGs were identified.A prognostic model with a high applicability(area under the curve=0.921)was constructed with 13 DEMRGs.Tumorigenesis of DLBCL was highly related to the neutrophil count.Four DEMRGs(PRXL2AB,CCN1,DECR2 and PHOSPHO1)with 32 TF-DEMRG,36 DEMRG-pathway,14 DEMRG-immune-cell,9 DEMRG-immune-gene-set,and 67 DEMRG-protein-chip interactions were used to construct the regulatory network.Conclusion:We provided a prognostic prediction model based on 13 DEMRGs for DLBCL.We found that phosphatase,orphan 1(PHOSPHO1)is positively regulated by regulatory factor X5(RFX5)and mediates MYC proto-oncogene(MYC)targeting the V2 pathway and neutrophils.

Racial Disparities in Survival Outcomes of Prostate Cancer Patients after Surgery for Bone Metastases

Introduction: This study reviewed patients’ demographic, clinical and treatment characteristics to identify prognostic factors associated with survival of prostate cancer after developing bone metastases. We explored the racial disparities in these factors and how they relate with survival. Methods: We conducted a retrospective study on 79 men diagnosed with bone metastasis secondary to prostate cancer who underwent surgery at a single institution?from November 1977 to June 2011. Descriptive statistics were used to summarize patients’ characteristics. The Kaplan-Meier method was used to estimate characteristics of the survival distribution using two origination points—diagnosis and surgery. Cox hazard regression explored the relationship between prognostic factors and overall survival. Results: The majority of men were White (n = 63;80%) followed by Black (n = 7;9%), Hispanic (n = 7;9%), and Asian (n = 2;2%). Multivariate factors associated with poorer survival after bone metastasis surgery included race (Black), Gleason score > 8, and radiation treatment. Patients not receiving radiation had a longer survival experience relative to patients who received radiation before or after surgery (10.3 vs 6.5 months;P = 0.030). There was an association of PSA level at the time of bone metastasis diagnosis with survival following diagnosis but prior to surgery. The median time interval (Tm in months) between prostate cancer diagnosis and bone metastasis diagnosis was 39.1 (White), 31.2 (Hispanic), 15 (Blacks) and 43 (Asians). Patients with Tm m > 35 months (HR = 3.22;P Conclusion: The median survival and time interval from prostate cancer diagnosis to bone metastasis diagnosis was shorter in Blacks with respect to other races. The more aggressive nature of the disease in Blacks is likely due to the biology of the disease rather than access to treatment.

A novel molecular classification method for osteosarcoma based on tumor cell differentiation trajectories

Subclassification of tumors based on molecular features may facilitate therapeutic choice and increase the response rate of cancer patients.However,the highly complex cell origin involved in osteosarcoma(OS)limits the utility of traditional bulk RNA sequencing for OS subclassification.Single-cell RNA sequencing(sc RNA-seq)holds great promise for identifying cell heterogeneity.However,this technique has rarely been used in the study of tumor subclassification.By analyzing sc RNA-seq data for six conventional OS and nine cancellous bone(CB)samples,we identified 29 clusters in OS and CB samples and discovered three differentiation trajectories from the cancer stem cell(CSC)-like subset,which allowed us to classify OS samples into three groups.The classification model was further examined using the TARGET dataset.Each subgroup of OS had different prognoses and possible drug sensitivities,and OS cells in the three differentiation branches showed distinct interactions with other clusters in the OS microenvironment.In addition,we verified the classification model through IHC staining in 138 OS samples,revealing a worse prognosis for Group B patients.Furthermore,we describe the novel transcriptional program of CSCs and highlight the activation of EZH2 in CSCs of OS.These findings provide a novel subclassification method based on sc RNA-seq and shed new light on the molecular features of CSCs in OS and may serve as valuable references for precision treatment for and therapeutic development in OS.

四肢软组织高度恶性血肿样肉瘤15例临床病理研究

目的:探讨血肿样高度恶性肉瘤(hematoma鄄likehigh鄄gradesarcoma,HLHGS)的临床病理特点及预后。方法:分析15例HLHGS患者的临床、磁共振成像(MRI)和病理资料。标本经10%中性甲醛固定,石蜡包埋,苏木精鄄伊红染色和免疫组织化学ABC标记。结果:15例HLHGS临床均诊断为“血肿”。肿瘤位于大腿6例,小腿2例,上臂2例,踝部、腋窝、前臂、腹股沟和臀部各1例。MRI检查示:①病变长径与短径比为2∶1;②对比增强时显示“血肿壁”上肿瘤结节;③T1水平病变中间带强度同骨骼肌,T2水平中度增强,但强度低于液体。病理检查示病变中出血成分>85%,肿瘤组织学类型为恶性纤维组织细胞瘤7例,平滑肌肉瘤4例,滑膜肉瘤、恶性周围神经鞘膜瘤、横纹肌肉瘤和软组织黏液性软骨肉瘤各1例。按美国癌症联合会肿瘤分期Ⅲb12例,Ⅳb3例。术后随访6～60个月,其中无瘤生存6例,带瘤生存5例,死于肿瘤4例。复发率为13.3%,转移率为53.3%,2年生存率为73.3%。结论:血肿样肉瘤是高度侵袭性的软组织肉瘤,但其临床表现、超声波检查和CT扫描及细针抽吸活检易误诊为良性血肿。MRI检查可显示肿瘤性结节。CT引导下穿刺能明确诊断。

Intraosseous Lipoma with Subsequent Esophageal Carcinoma Metastasis

Background: This case report describes a well documented proximal femoral metadiaphysis intraosseous lipoma which later developed metastasis from a new esophageal cancer. Metastatic disease to benign conditions is a rare finding. To the best of our knowledge, this is the first reported case of metastatic disease to an intraosseous lipoma. Case Description: The metastatic deposit was initially detected by plain-film radiography, performed to evaluate new onset right hip pain, as possible new cortical breakthrough with irregularity in the site of previously known proximal right femur intraosseous lipoma. Concurrent follow-up PET/CT study showed a new hypermetabolic focus within the known intraosseous lipoma indicating a new metastasis that was confirmed with an MRI as a new enhancing mass within the preexisting intraosseous lipoma. Subsequently, an MRI-guided biopsy and eventually surgical excision was performed providing the histological samples for radiologic-pathologic correlation. Purpose and Clinical Relevance: Clinicians need to be aware that unusual, complex patterns within benign lesions may be a reflection of unexpected conditions, such as insufficiency injury, malignant transformation and secondary metastatic disease, as exemplified by our case report.

A multifunctional biomimetic nanoplatform for image-guideded photothermal-ferroptotic synergistic osteosarcoma therapy

Much effort has been devoted to improving treatment efficiency for osteosarcoma(OS).However,most current approaches result in poor therapeutic responses,thus indicating the need for the development of other therapeutic options.This study developed a multifunctional nanoparticle,PDA-MOF-E-M,an aggregation of OS targeting,programmed death targeting,and near-infrared(NIR)-aided targeting.At the same time,a multifunctional nanoparticle that utilises Fe-MOFs to create a cellular iron-rich environment and erastin as a ferroptosis inducer while ensuring targeted delivery to OS cells through cell membrane encapsulation is presented.The combination of PDA-MOF-E-M and PTT increased intracellular ROS and LPO levels and induced ferroptosis-related protein expression.A PDA-based PTT combined with erastin showed significant synergistic therapeutic improvement in the anti-tumour efficiency of the nanoparticle in vitro and vivo.The multifunctional nanoparticle efficiently prevents the osteoclasia progression of OS xenograft bone tumors in vivo.Finally,this study provides guidance and a point of reference for clinical approaches to treating OS.

Diagnosis and Differential Diagnosis of Desmoplastic Fibroblastoma by Clinical, Radiological, and Histopathological Analyses

Background： Desmoplastic fibroblastoma （collagenous fibroma） is an uncommon benign soft-tissue tumor, rarely involving bone. It shares some overlapping features with other infiltrate tumors, such as desmoid-type fibromatosis, neurofibroma, and low-grade fibromyxoid sarcoma. The misdiagnosis may cause unnecessary surgical overtreatment, especially for those involving bone. In order to deepen the understanding of the diagnosis and differential diagnosis of desmoplastic fibroblastoma, we planned to analyze the clinical, radiological, and histopathological features and the outcome of desmoplastic fibroblastoma on the basis of case analysis and literature review. Methods： Sixteen cases were retrieved from the surgical pathology records from May 2011 to April 2016 in the Department of Pathology in Beijing Jishuitan Hospital. Formalin-fixed, paraffin-embedded specimens of 16 cases of desmoplastic fibroblastoma were collected. Hematoxylin and eosin stain and immunohistochemistry were used to observe the histological features of desmoplastic fibroblastoma of soft tissue and bone. The images for diagnosis obtained from the ultrasonic examination, X-ray, magnetic resonance imaging, and computed tomography were used to observe the radiological features. Related literatures were retrieved from the PubMed and CNKI databases. Results： Sixteen cases of desmoplastic fibroblastoma of soft tissue were located in the hand （n = 7）, loot （n = 4）, upper arm （n = 1）, shoulder （n = 1）, forearm （n = 2）, and one case occurred in the proximal femur. Age ranged from 32 to 82 years （median age： 58 years）. There were six females and ten males. Histologically, the lesions of soft tissue appeared as well-circumscribed masses with abundant collagenous matrix and low vascularity. Tumor cells were stellate- or spindle-shaped and uniformly distributed within the extracellular matrix. In five cases, the desmoplastic fibroblastoma were found to have infiltrated into the skeletal muscle tissue. In one case ofdesmoplastic fibroblastoma of bone, radiographs revealed osteolytically well-defined lesion, lmmunohistochemistry stain showed that vimentin and smooth muscle actin were positive in all cases of desmoplastic fibroblastoma. Conclusions： Desmoplastic fibroblastoma （collagenous fibroma） has prominent clinical, histopathological, and radiological features. Before the differential diagnosis from other tumors is obtained by thorough analysis and comparison of the similar and different characteristics, the appropriate surgical management and accurate prognosis evaluation could not be delivered to the patient.

Analysis of soft tissue sarcomas in 1118 cases

Background It is important to analyze and compare soft tissue sarcomas periodically so as to update the incidence, the clinical diagnosis, the treatment, and the ongoing research. The present study was conducted to determine the relative frequency of each type of soft tissue sarcoma.Methods A total of 1118 cases of primary soft tissue sarcomas treated between January 1993 and December 2006 were evaluated in a retrospective analysis.Results According to the pathologic grouping, the diseases with the highest proportion were malignant fibrous histiocytomas （35.24%）, synovial sarcomas （17.08%）, liposarcomas （16.28%）, and rhabdomyosarcomas （12.61%）. Soft tissue sarcomas were detected in every age group and occurred in all parts of the body. The number of cases increased gradually over the years.Conclusions Malignant fibrous histiocytomas had the highest frequency among the soft tissue sarcomas. The number of cases increased gradually over the years.

Subchondral bone grafting reduces degenerative change of knee joint in patients of giant cell tumor of bone

Background Giant cell tumors （GCTs） most commonly occur around the knee.The most beneficial procedure for this disease has been extensive curettage with reconstruction.However,since many GCTs may compromise the subchondral bone,surgery can further jeopardize the articular cartilage and result in secondary osteoarthritis.In this study,we aimed to determine the factors associated with the development of degenerative arthritis and the effect of bone grafting on the prevention of secondary osteoarthritis.Methods We retrospectively analyzed 76 patients with GCT around the knee.The mean age at first diagnosis was 31.1 years.Surgical treatments included extensive curettage and cementation with or without bone grafting in the subchondral bone.Patient follow-up was a median duration of 35 months,ranging from 18 to 113 months.Results The local recurrence rate was 5.3％ （4/76）.Secondary degenerative changes occurred in 30.3％ （23/76） of the patients.Less than 10 mm of the residual thickness of the remaining subchondral bone was correlated with secondary degenerative changes in 57 patients （P ＜0.001）.Of these 57 patients,56.5％ （13/23） treated with bone cement reconstruction alone developed secondary degenerative changes; following bone grafting,the rate decreased to 29.4％（10/34）,with a statistically significant difference （P=0.041）.Conclusions GCT patients with less residual thickness of the subchondral bone are more likely to develop degenerative arthritis after curettage.Bone grafting in the subchondral bone area is recommended when the residual thickness of the subchondral bone is less than 10 mm.

A comparative study of calcium sulfate artificial bone graft versus allograft in the reconstruction of bone defect after tumor curettage

Background Cavity reconstruction after benign bone tumor removal is varied and controversial.AIIograft is widely used but is associated with complications.New bone substitutes,such as calcium sulfate artificial bone,have been introduced for bone tumor operation.However,the bone healing response of artificial bone has not been compared with allograft bone.We therefore compared calcium sulfate grafts （study group） with bone allografts （control group） for the treatment of benign bone tumors.Methods We retrospectively reviewed 50 patients who underwent calcium sulfate reconstruction and 50 patients who underwent allograft cancellous bone reconstruction.The two groups were well matched.The mean follow-up time of the study group was 19.9 （12-55） months.We investigated bone healing response,complications,and factors affecting bone healing.Results At the last follow-up,84％ （42/50） of cases in the study group and 62％ （31/50） of cases in the control group had achieved clinical healing （P=0.013）.The initial healing rate showed no significant difference between the two groups （100％ vs.96％,P=0.153）.The mean healing times for calcium sulfate and allograft bone were 9.6 （3-42） months and 13.8 （3-36） months,respectively （P ＜0.01）.Complications in the study group were minor and resolved.Implant volume was a significant factor affecting bone healing.Conclusion The calcium sulfate bone substitute showed a satisfactory healing outcome and safety profile in reconstruction of bone defects after benign bone tumor curettage,especially in smaller cavities.

Computer Navigation-aided Resection of Sacral Chordomas

Background： Resection of sacral chordomas is challenging. The anatomy is complex, and there are often no bony landmarks to guide the resection. Achieving adequate surgical margins is, therefore, difficult, and the recurrence rate is high. Use of computer navigation may allow optimal preoperative planning and improve precision in tumor resection. The purpose of this study was to evaluate the safety and feasibility of computer navigation-aided resection of sacral chordomas. Methods： Between 2007 and 2013, a total of 26 patients with sacral chordoma underwent computer navigation-aided surgery were included and followed for a minimum of 18 months. There were 21 primary cases and 5 recurrent cases, with a mean age of 55.8 years old （range： 35 84 years old）. Tumors were located above the level of the $3 neural foramen in 23 patients and below the level of the $3 neural foramen in 3 patients. Three-dimensional images were reconstructed with a computed tomography-based navigation system combined with the magnetic resonance images using the navigation software. Tumors were resected via a posterior approach assisted by the computer navigation. Mean follow-up was 38.6 months （range： 18-84 months）. Results： Mean operative time was 307 min. Mean intraoperative blood loss was 3065 ml. For computer navigation, the mean registration deviation during surgery was 1.7 ram. There were 18 wide resections, 4 marginal resections, and 4 intralesional resections. All patients were alive at the final follow-up, with 2 （7.7%） exhibiting tumor recurrence. The other 24 patients were tumor-free. The mean Musculoskeletal Tumor Society Score was 27.3 （range： 19-30）. Conclusions： Computer-assisted navigation can be safely applied to the resection of the sacral chordomas, allowing execution of preoperative plans, and achieving good oncological outcomes. Nevertheless, this needs to be accomplished by surgeons with adequate experience and skill.

Osteoid osteoma of the patella： report of two cases

Osteoid osteoma is very rarely located in the patella, and can represent a significant diagnostic challenge, resulting in a delay of treatment. Patients with osteoid osteoma of the patella often present with knee pain that is also a typical symptom of trauma or of other diseases such as arthritis, which are much more common than osteoid osteoma. We present two young male patients diagnosed with osteoid osteoma of the patella. Each of these patients had a history of intense knee pain; however, accurate diagnosis of osteoid osteoma in the patella had been delayed for more than one year. Computed tomography （CT） scans or magnetic resonance imaging （MRI） showed a circumscribed lesion of the patella in both patients, whereas X-ray examination （posteroantedor projection） was not able to detect the tumor. Different surgical procedures were performed in these patients for resection of the tumors, and the pathology findings confirmed the diagnosis of osteoid osteoma. Both patients recovered completely from surgery.