Jens O Anders

First metatarsophalangeal joint replacement: the method of choice for end-stage hallux rigidus?

Replacement of the first metatarsophalangeal (MTP) joint remains critical because of complex biomechanical conditions and implant fixation. After a 3-year follow-up, most patients who experienced an MTP joint replacement were extremely satisfied with the outcome. Plantar pressure distribution revealed a marked improvement. Nevertheless, recovery of MTP dorsiflexion was limited and joint stability worsened. Radiologically, one-third of the prostheses showed radiolucent lines as a sign of implant loosening. MTP replacement offers distinct advantages in the treatment of end-stage hallux rigidus, but requires further research on implant design and osseous fixation.

Solitary fibrous tumor in the thigh: review of the literature

Solitary fibrous tumors (SFT) of extremities, especially the thighs are very rare. Despite SFTs are generally benign, well-circumscribed soft tissue tumors new cases should be presented and followed up carefully to monitor their biological behavior. In general for tumor classification a biopsy is state of the art. Histological including immunohistochemical patterns for SFTs are defined. MRI and ultrasound are not sufficient for differential diagnosis. Once property identified and defined by size and location, resection with intact tumor capsule may result in full recovery of the patient. Reviewing the literature there are no validated reasons for a wider resection. The current patient was a 41-year-old male. Four years after an arthroscopy of the left knee the patient has been suffering an ongoing swelling of the lateral thigh. Because MRI scan data suggested a synovial sarcoma a biopsy was performed. The tumor was classified as a benign SFT. The diagnosis based on histological findings and the presence of the positive immunohistochemical markers Vimentin, CD34, and CD99. The complete tumor resection with intact capsule was achieved in a final operation. Clinical and in MRI after 54-month outcome period there were no local recurrences.

Histological and cell biological characterization of dissected cartilage fragments in human osteochondritis dissecans of the femoral condyle

Introduction: Osteochondritis dissecans (OCD) within the weight-bearing femoral condyle carries a high risk of osteoarthritis. The definitive pathogenetic cause is unclear. Therefore biochemical and cellular features of OCD were analyzed and compared to macroscopically normal cartilage of the same joint surface. Materials and methods: Dissected fragments from 14 patients and biopsies of normal cartilage from the intercondylar notch as controls were harvested at arthroscopy. Staining with safranin O to monitor proteoglycan content, alkaline phosphatase activity, and immunohistochemistry with mouse monoclonal antibodies to collagen types I, II, and X. Chondrocytes were isolated for RT-PCR to detect GAPDH, collagen types I, II, X, aggrecan, TGF-β, BMP-7, bFGF, VEGF and IL-1. Results: The dissected cartilage displayed significant variability. Apart from normal cartilage matrix components also atypical molecules such as collagen type X and alkaline phosphatase were detected at the tidemark but also across the entire dissecate, suggesting chondrocyte hypertrophy. Extended fibrous degeneration associated with collagen type I deposition was observed at the surface and may indicate chondrocyte dedifferentiation. Viable cells could be extracted from OCD and notch. Both expressed similar mRNA levels for matrix molecules, growth factors, and interleukin-1 (IL-1), however significantly more Col X mRNA was detected in dissecates. Conclusion: Histology suggests focal alteration of cartilage matrix originating from the basis of the joint cartilage, potentially the mineralized layer or subchondral bone. The molecular analysis indicates a disorganization of cartilage homeostasis across the joint accompanied by embryogenetic processes. The surprisingly high viability and quality of the extracted cells suggests a still preserved intrinsic repair capacity of those vital dissecates.

Acetylcholinesterase assay for cerebrospinal fluid using bupivacaine to inhibit butyrylcholinesterase

BackgroundMost test systems for acetylcholinesterase activity (E.C.3.1.1.7.) are using toxic inhibitors (BW284c51 and iso-OMPA) to distinguish the enzyme from butyrylcholinesterase (E.C.3.1.1.8.) which occurs simultaneously in the cerebrospinal fluid. Applying Ellmans colorimetric method, we were looking for a non-toxic inhibitor to restrain butyrylcholinesterase activity. Based on results of previous in vitro studies bupivacaine emerged to be a suitable inhibitor.ResultsPharmacokinetic investigations with purified cholinesterases have shown maximum inhibition of butyrylcholinesterase activity and minimal interference with acetylcholinesterase activity at bupivacaine final concentrations between 0.1 and 0.5 mmol/l. Based on detailed analysis of pharmacokinetic data we developed three equations representing enzyme inhibition at bupivacaine concentrations of 0.1, 0.2 and 0.5 mmol/l. These equations allow us to calculate the acetylcholinesterase activity in solutions containing both cholinesterases utilizing the extinction differences measured spectrophotometrically in samples with and without bupivacaine. The accuracy of the bupivacaine-inhibition test could be confirmed by investigations on solutions of both purified cholinesterases and on samples of human cerebrospinal fluid. If butyrylcholinesterase activity has to be assessed simultaneously an independent test using butyrylthiocholine iodide as substrate (final concentration 5 mmol/l) has to be conducted.ConclusionsThe bupivacaine-inhibition test is a reliable method using spectrophotometrical techniques to measure acetylcholinesterase activity in cerebrospinal fluid. It avoids the use of toxic inhibitors for differentiation of acetylcholinesterase from butyrylcholinesterase in fluids containing both enzymes. Our investigations suggest that bupivacaine concentrations of 0.1, 0.2 or 0.5 mmol/l can be applied with the same effect using 1 mmol/l acetylthiocholine iodide as substrate.

Myofibroblastic bone tumor of the toe: case report.

Level of Evidence: V, Expert Opinion