Angioimmunoblastic T-cell lymphoma is a peripheral T-cell lymphoma derived from follicular T-helper cells. Highthroughput genomic sequencing studies have shown that angioimmunoblastic T-cell lymphoma carries frequent mutations in RHOA G17V and IDH2 R172 genes. The clinico-pathological features of angioimmunoblastic T-cell lymphoma cases with RHOA G17V mutations have been addressed; however, similar studies for IDH2 mutated cases are lacking. Therefore, the aim of the present study was to evaluate the pathological features of angioimmunoblastic T-cell lymphoma with IDH2 mutations. In order to identify cases with IDH2 mutations, 50 cases previously diagnosed as angioimmunoblastic T-cell lymphoma were subjected to next-generation sequencing analysis using a custom panel covering four genes frequently mutated in angioimmunoblastic T-cell lymphoma including DNMT3A, TET2, IDH2 and RHOA. All cases were analyzed for PD1, ICOS, CXCL13, CD10, BCL6, CD21, CD23 and EBER in situ hybridization. Mutational analysis recognized three groups. Group 1: IDH2 R172 mutations were identified in 20 cases (40%). All cases carried RHOA G17V mutations. Group 2: RHOA G17V mutations without IDH2 R172 mutation were identified in 16 cases (32%), and Group 3: 14 cases (28%) without RHOA G17V or IDH2 R172 mutations. Morphologically, angioimmunoblastic T-cell lymphoma cases with IDH2 R172 mutations were characterized by the presence of medium to large clear cells (p = 0.00001), and a follicular T-helper phenotype with the particular feature of strong CD10 (p = 0.0268) and CXCL13 expression (p = 0.0346). Interestingly, TET2 mutations were identified in 32 of 33 (97%) cases with IDH2 R172 and/or RHOA G17V mutations whereas only 55% of angioimmunoblastic Tcell lymphoma cases wild-type for these two genes carried TET2 mutations (p = 0.0022). In contrast, DNMT3A mutations were found in 48% of the cases and were equally distributed in the three groups. In conclusion, our results support the results of gene expression profiling studies suggesting that IDH2 R172 mutations define a unique subgroup within angioimmunoblastic T-cell lymphoma with strong follicular T-helper-like phenotype and characteristic morphological features.

Introduction The modified Broström operation (MBO) has found widespread use in the therapy of lateral chronic ankle instability (CAI). However, alternative surgical techniques like the open reconstruction using a periosteal flap (RPF) are still an important part of the surgical treatment of lateral CAI. Both procedures differ in terms of the reconstruction material used and the surgical procedure. Comparative studies on the surgical therapy of CAI are limited and generally refer to similar surgical procedures. Aim of this study was to compare the arthroscopic MBO and the RPF. Materials and methods We retrospectively analysed 25 patients with lateral CAI after a tear of the anterior talofibular ligament (ATFL). 14 patients received arthroscopic MBO and 11 patients received RPF. We compared the postoperative outcome between both groups with respect to subjective instability, the number of ankle sprains, pain, complications and follow-up operations as well as the American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score. Results Both surgical procedures resulted in a significant improvement in pain, in subjective instability, in the reduction in the frequency of ankle sprains and improvement in the AOFAS ankle-hindfoot score one year postoperatively. Three months postoperatively, the values for pain and instability of the MBO group were significantly better compared to the RPF. One year after the operation, these differences were evened out. Also in terms of complications and follow-up operations, no significant difference was found between the two procedures. Conclusions Both surgical procedures give very good results one year postoperatively in terms of pain, instability, function and complication rate. With significantly better results regarding pain and instability three months postoperatively, the MBO allows a faster recovery in patients operated with this technique.

Background Cartilage is a mechanically highly stressed tissue in the human body and an important part of synovial joints. The joint cartilage is lubricated by synovial fluid with hyaluronic acid (HA) as main component. However, in joints with osteoarthritis HA has a lower concentration and molecular weight compared to healthy joints. In recent years, the intra-articular injection of therapeutic HA lubricant, has become a popular therapy. The effect of HA application on the friction of a complete joint with physiological movement needs to be further determined. Methods The aim of the present study was to evaluate the lubrication effect of the joint by three lubricants (NaCl, fetal calf serum (FCS) and HA) and their effect on the friction in nine complete ovine carpo-metacarpal joints. The joints were mounted on a material testing machine and a physiological movement with 10° rotation was simulated with ascending axial load (100 – 400 N). Specimens were tested native, with cartilage damage caused by drying out and relubricated. Dissipated energy (DE) as a measure of friction was recorded and compared. Results Investigating the effect of axial load, we found significant differences in DE between all axial load steps (p < .001), however, only for the defect cartilage. Furthermore, we could document an increase in DE from native (Mean: 15.0 mJ/cycle, SD: 8.98) to cartilage damage (M: 74.4 mJ/cycle, SD: 79.02) and a decrease after relubrication to 23.6 mJ/cycle (SD: 18.47). Finally, we compared the DE values for NaCl, FCS and HA. The highest values were detected for NaCl (MNorm = 16.4 mJ/cycle, SD: 19.14). HA achieved the lowest value (MNorm = 4.3 mJ/cycle, SD: 4.31), although the gap to FCS (MNorm = 5.1 mJ/cycle, SD: 7.07) was small. Conclusions We were able to elucidate three effects in joints with cartilage damage. First, the friction in damaged joints increases significantly compared to native joints. Second, especially in damaged joints, the friction increases significantly more with increased axial load compared to native or relubricated joints. Third, lubricants can achieve an enormous decrease in friction. Comparing different lubricants, our results indicate the highest decrease in friction for HA.

The choice of spacer in the interim phase of two-stage revision hip arthroplasty is crucial. Conventional concepts like a Girdlestone situation, handformed or preformed bone cement spacers show complications like soft-tissue contractions, abrasion of bone cement particles, dislocation, breakage and a low level of mobility in the interim phase. To address these disadvantages, the senior author developed a new technique for custom-made spacers in septic two-stage revision of total hip arthroplasties using prosthetic implants with individualized antibiotic mixture in the cement applying a mechanical inferior cementation method. The aim of this study was to evaluate the results of these spacers with respect to their non-inferiority in terms of reinfection and survival-rate of the new implant and to describe the complications associated with this procedure. Our collective consisted of 130 patients with a median follow-up of nearly five years. With a reinfect-free rate of 92% and a spacer-related complication rate of 10% (8% articular dislocation, 1% periprosthetic joint fracture, 1% breakage), this procedure seems to be safe and superior regarding complications compared to conventional concepts. Further studies are necessary to show the clinical benefit of this procedure.