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For patients who have anterior hip pain evaluated by Patrick's test and tenderness at Scarpa's triangle, we perform periarticular debridement based on the hypothesis that extra-articular pathologies are responsible for the hip pain. The purpose of this study was to categorize the endoscopic extra-articular findings and to evaluate the clinical significance of periarticular pathologies in anterior hip pain. Arthroscopic findings of 77 patients who underwent periarthritic debridement were evaluated. As extra-articular pathologies, injuries of the direct head and reflective head of the rectus femoris muscle were evaluated. A thin layer of fat tissue normally exists on the anterior inferior iliac spine (AIIS), the attachment site of the direct head of the rectus femoris muscle. The macroscopic appearance of the fat pad on the AIIS was categorized as normal, blood vessel-rich adipose tissue or adipose tissue with fibrosis or scar formation and histologically confirmed. Adhesion of gluteal muscles to the joint capsule was also evaluated. Of the 77 patients, 75 had rupture of the direct head of the rectus femoris. In contrast, rupture of the reflective head was extremely rare. Seven patients had a normal fat pad on the AIIS, 11 had blood vessel-rich adipose tissue and 55 had adipose tissue with fibrosis. Fat tissue was completely replaced by fibrous scar tissue in another 4 patients. In 64 patients, adhesion between the anterior joint capsule and gluteus muscles was marked. Groin pain disappeared soon after the operation even when labral tears were not repaired and all patients returned to daily life and sports activities within 2 weeks after operation. Rectus femoris tendinosis, fibrosis of the AIIS fat pad, and adhesion of gluteal and rectus femoris muscles are common extra-articular pathologies in patients with anterior hip pain. Management of only these lesions induces rapid relief of anterior hip pain even in the absence of labral tear repair. My observations suggest that it is desirable to be aware of the presence of periarticular pathologies as a cause of groin pain.

Purpose The aim of this study was to obtain data on chondral damage and compare the damage patterns of various hip disorders. Methods Data were collected at 100 consecutive arthroscopies, and chondral lesions were recorded on anatomic articular maps divided into different anatomical zones. This geographic zone method made it possible to analyze the ICRS grade and location in relation to the hip morphology. Results The distribution and degree of the chondral defects showed a hip morphology-specific pattern. On the acetabular side, there were high incidences of full-thickness defects in the anterior–superior zone and the middle superior zone in patients with femoroacetabular impingement (FAI) (zone 2: 25.4 % grade 3, 35.5 % grade 4; zone 3: 20.3 % grade 3, 37.2 % grade 4) and borderline dysplasia (zone 2: 31.2 % grade 3, 12.5 % grade 4; zone 3: 18.7 % grade 3, 25 % grade 4). However, in patients with joint laxity, partial-thickness defects were dominant (zone 2: 50 % grade 1, 15 % grade 2; zone 3: 40 % grade 1). In patients with acetabular dysplasia, full-thickness defects extended even to the posterior superior zone (zone 4: 80 % grade 4). On the femoral head side, the incidence of full-thickness cartilage injuries was high in patients with FAI and borderline dysplasia compared to those with joint laxity and acetabular dysplasia. Conclusion Evaluation of chondral damage using the geographic zone method showed that the pattern of cartilage damage was influenced by hip morphology. Understanding of hip disorder-specific chondral damage patterns may be useful for the development of arthroscopic classification of hip disorders and may lead to the establishment of treatment guidelines. Level of evidence Diagnostic study, Level III.

Osteosarcoma (OS) is a highly malignant bone tumor and the prognosis for non‐responders to chemotherapy remains poor. Previous studies have shown that human sarcomas contain sarcoma‐initiating cells (SIC), which have the characteristics of high tumorigenesis and resistance to chemotherapy. In the present study, we characterized SIC of a novel OS cell line, screened for SIC‐related genes, and tried to regulate the proliferation of OS by metabolic interference. Initially, we established a new human OS cell line (OS13) and isolated clones showing higher tumorigenesis as SIC (OSHIGH) and counterpart clones. OSHIGH cells showed chemoresistance and their metabolism highly depended on aerobic glycolysis and suppressed oxidative phosphorylation. Using RNA‐sequencing, we identified LIN28B as a SIC‐related gene highly expressed in OSHIGH cells. mRNA of LIN28B was expressed in sarcoma cell lines including OS13, but its expression was not detectable in normal organs other than the testis and placenta. LIN28B protein was also detected in various sarcoma tissues. Knockdown of LIN28B in OS13 cells reduced tumorigenesis, decreased chemoresistance, and reversed oxidative phosphorylation function. Combination therapy consisting of a glycolysis inhibitor and low‐dose chemotherapy had antitumor effects. In conclusion, manipulation of glycolysis combined with chemotherapy might be a good adjuvant treatment for OS. Development of immunotherapy targeting LIN28B, a so‐called cancer/testis antigen, might be a good approach. Osteosarcoma‐initiating cell antigen LIN28B was expressed in sarcoma tissues. ES, epithelioid sarcoma; MFS, myxofibrosarcoma; OS, osteosarcoma; SS, synovial sarcoma.

With the goal of establishing efficacious peptide‐based immunotherapy for patients with bone and soft tissue sarcomas, we previously identified the cytotoxic T lymphocyte‐defined osteosarcoma antigenic gene Papillomavirus binding factor. The present study was designed to determine the status of HLA class I expression in osteosarcoma and other bone and soft tissue sarcomas. Seventy‐four formalin‐fixed paraffin‐embedded specimens of various bone and soft tissue sarcomas, including 33 osteosarcomas, were stained with the anti‐HLA class I monoclonal antibody EMR8‐5, which we recently generated. The expression of HLA class I was lost or downregulated in 46 of these specimens (62%). With respect to osteosarcoma, loss or downregulation of HLA class I expression was seen in 13 (52%) of 25 primary tumors and seven (88%) of eight metastatic tumors. In six of 11 HLA class I‐negative osteosarcoma specimens, the expression of β‐2 microglobulin was also lost. Subsequently the prognostic significance of HLA class I expression was analyzed in 21 patients with osteosarcoma who had completed multidrug neoadjuvant chemotherapy and undergone adequate surgery. Patients with osteosarcoma highly expressing HLA class I showed significantly better overall and event‐free survival than those with HLA class I‐negative osteosarcoma. In contrast, such prognostic significance of HLA class I expression was not found in 15 patients with malignant fibrous histiocytoma of soft tissue. These findings suggest that the class I‐restricted cytotoxic T lymphocyte pathway plays a major role in immune surveillance of patients with osteosarcoma. (Cancer Sci 2006; 97: 1374–1380)

Iliopectineal bursitis usually develops subsequent to other hip pathologies and can often be treated conservatively. However, when conservative treatment fails or the enlarged bursa causes pain or compression of the surrounding neurovascular structures, surgery may be required. Most previous studies have described open surgeries, and reports on endoscopy are very limited. We present a case of iliopectineal bursitis associated with developmental dysplasia of the hip (DDH) that was successfully treated endoscopically. A 16-year-old female with a one-year history of right inguinal pain was referred to our department. She was diagnosed with a hip ganglion and treated with needle aspiration nine times by her previous doctor. Radiographs revealed bilateral DDH without narrowing of the joint space. Magnetic resonance imaging revealed a distinct mass in the deep layer of the iliopsoas muscle, and communication between the mass and the hip joint was observed on ultrasonography. Endoscopic debridement and resection were performed based on the diagnosis of iliopectineal bursitis. We partially debrided the medial side of the rectus femoris muscle toward the deep layer and resected the bursa. We observed a burst of concentrated content from the bursa and confirmed the disappearance of the mass by intraoperative ultrasonography. The postoperative course was good, and there were no functional restrictions or symptom recurrence at two-year postoperatively. Endoscopic resection for repetitive iliopectineal bursitis without an intraarticular procedure does not induce hip instability in patients with DDH and is a minimally invasive cosmetic procedure, and superior to open surgery, especially in young women.

Epithelioid sarcoma (ES) is a relatively rare, highly malignant soft tissue sarcoma. The mainstay of treatment is resection or amputation. Currently other therapeutic options available for this disease are limited. Therefore, a novel therapeutic option needs to be developed. In the present study, we established a new human ES cell line (ESX) and analyzed the characteristics of its cancer stem-like cells/cancer-initiating cells (CSCs/CICs) based on ALDH1 activity. We demonstrated that a subpopulation of ESX cells with high ALDH1 activity (ALDH(high) cells) correlated with enhanced clonogenic ability, sphere-formation ability, and invasiveness in vitro and showed higher tumorigenicity in vivo. Next, using gene expression profiling, we identified CD109, a GPI-anchored protein upregulated in the ALDH(high) cells. CD109 mRNA was highly expressed in various sarcoma cell lines, but weakly expressed in normal adult tissues. CD109-positive cells in ESX predominantly formed spheres in culture, whereas siCD109 reduced ALDH1 expression and inhibited the cell proliferation in vitro. Subsequently, we evaluated the expression of CD109 protein in 80 clinical specimens of soft tissue sarcoma. We found a strong correlation between CD109 protein expression and the prognosis (P = 0.009). In conclusion, CD109 might be a CSC/CIC marker in epithelioid sarcoma. Moreover, CD109 is a promising prognostic biomarker and a molecular target of cancer therapy for sarcomas including ES.

In the present study, we evaluated the safety and effectiveness of SYT‐SSX‐derived peptide vaccines in patients with advanced synovial sarcoma. A 9‐mer peptide spanning the SYT‐SSX fusion region (B peptide) and its HLA‐A*2402 anchor substitute (K9I) were synthesized. In Protocols A1 and A2, vaccines with peptide alone were administered subcutaneously six times at 14‐day intervals. The B peptide was used in Protocol A1, whereas the K9I peptide was used in Protocol A2. In Protocols B1 and B2, the peptide was mixed with incomplete Freund's adjuvant and then administered subcutaneously six times at 14‐day intervals. In addition, interferon‐α was injected subcutaneously on the same day and again 3 days after the vaccination. The B peptide and K9I peptide were used in Protocols B1 and B2, respectively. In total, 21 patients (12 men, nine women; mean age 43.6 years) were enrolled in the present study. Each patient had multiple metastatic lesions of the lung. Thirteen patients completed the six‐injection vaccination schedule. One patient developed intracerebral hemorrhage after the second vaccination. Delayed‐type hypersensitivity skin tests were negative in all patients. Nine patients showed a greater than twofold increase in the frequency of CTLs in tetramer analysis. Recognized disease progression occurred in all but one of the nine patients in Protocols A1 and A2. In contrast, half the 12 patients had stable disease during the vaccination period in Protocols B1 and B2. Of note, one patient showed transient shrinkage of a metastatic lesion. The response of the patients to the B protocols is encouraging and warrants further investigation.

Purpose: A clinical feature of myxofibrosarcoma is local recurrence, but knowledge about distant metastasis is sparse. We evaluated the tendency of clinical and histological features of metastasis in myxofibrosarcoma patients. Methods: Fifty-eight patients with myxofibrosarcoma were treated in our hospitals, and a total of 16 consecutive patients with distant metastases were included in this retrospective study (9 males and 7 females, with a mean age of 77 years). Because there was no patient complicated by both lung and lymph node metastases, we compared the age, sex, tumor size and location, French Federation of Cancer Centers Sarcoma Group (FNCLCC) grade, American Joint Committee on Cancer (AJCC) stage, and times of the first metastasis from the initial examination between the lung and lymph node groups. In addition, we examined factors affecting the prognosis. Results: The median follow-up period was 42.9 months (range 8-142). Eleven of 16 patients developed pulmonary metastases. The sites of extra pulmonary metastases were the lymph nodes in 5 patients, bone in 1, subcutaneous in 1, intramuscular in 1, and peritoneum in 1. The median time for patients to develop distant metastases was 17.4 months (range 0-59). The time until the onset of the first metastasis in the lung metastasis group was significantly shorter than in the lymph node group (p < 0.05). Also, the survival rate in the lymph node metastasis group was better than in the lung metastasis group (p < 0.05). Conclusions: Not only lung metastasis but also lymph node metastasis occurs frequently in myxofibrosarcoma patients. Myxofibrosarcoma with lung metastasis is more aggressive than the type with lymph node metastasis.

Objective Myxofibrosarcoma often shows abnormal signal infiltration along the fascial plane on magnetic resonance imaging (MRI). The objective was to describe this MRI characteristic of myxofibrosarcoma with pathologic findings for comparison. Materials and methods Clinical, histological, and imaging data for 21 patients with myxofibrosarcoma were reviewed retrospectively. Results Seventeen tumors showed a diffuse infiltrative pattern on MRI. All tumors with diffuse infiltrative growth pattern showed borderless extension of atypical cells with moderate nuclear atypia to the muscle fascia. Notably, the remaining four patients with focal growth pattern on MRI also demonstrated infiltrative growth pattern histologically suggesting that myxofibrosarcoma shows an infiltrative growth property even in the lack of infiltrative growth pattern on MRI. Conclusion Most myxofibrosarcoma show an infiltrative growth pattern histologically. Orthopedic oncologist should pay careful attention to accurately assess tumor extension. It seems prudent to resect the entire area of abnormal signal extension seen on MRI whenever possible to obtain an adequate surgical margin of myxofibrosarcoma.

Myxofibrosarcoma is characterized by a high local recurrence rate despite optimal surgical treatment. The definition of prognostic factors for recurrence offers high-risk patients a closer follow-up and a multi-disciplinary therapeutic approach. A cohort of 23 patients treated for primary myxofibrosarcoma was retrospectively analyzed. The patients (sex and age), tumors (size, stage, tumor location, bone and/or joint attachment), radiological findings (abnormal signal extension in MRI), histological findings (FNCLCC grade and microscopic extension along the muscle fascia), and treatment (surgical margin) characteristics were included in univariate prognostic factor analysis. After a median follow-up of 63.3 months (range 15–191), the overall recurrence rate was 34.7%. Median time between initial surgery and recurrence was 24.8 months (range 8–52). Inadequate surgical margins (p = 0.026) and bone and/or joint attachment (p = 0.001) were associated with an increased recurrence rate. For the further improvement of local recurrence-free survival of patients with myxofibrosarcoma, accurate diagnosis of the tumor extension and adequate planning for the surgical margin should be focused on in cases with bone and/or joint attachment.