The Lysosomal Protein Arylsulfatase B Is a Key Enzyme Involved in Skeletal Turnover.

Skeletal pathologies are frequently observed in lysosomal storage disorders, yet the relevance of specific lysosomal enzymes in bone remodeling cell types is poorly defined. Two lysosomal enzymes, ie, cathepsin K (Ctsk) and Acp5 (also known as tartrate-resistant acid phosphatase), have long been known as molecular marker proteins of differentiated osteoclasts. However, whereas the cysteine protease Ctsk is directly involved in the degradation of bone matrix proteins, the molecular function of Acp5 in osteoclasts is still unknown.

Arthroscopic patellar release allows timely return to performance in professional and amateur athletes with chronic patellar tendinopathy.

Purpose: Return to sports rates in amateur and professional athletes with chronic patellar tendinopathy following arthroscopic patellar release are unpredictable. The present study aims to analyse the effectiveness of arthroscopic patellar release in professional compared to amateur athletes.

Methods: A total of 34 amateur and 20 professional athletes with chronic patellar tendinopathy, refractory to conservative treatment, were studied prospectively and underwent arthroscopic tendon release at the inferior patellar pole.

Impaired proteoglycan glycosylation, elevated TGF-β signaling, and abnormal osteoblast differentiation as the basis for bone fragility in a mouse model for gerodermia osteodysplastica.

Gerodermia osteodysplastica (GO) is characterized by skin laxity and early-onset osteoporosis. GORAB, the responsible disease gene, encodes a small Golgi protein of poorly characterized function. To circumvent neonatal lethality of the GorabNull full knockout, Gorab was conditionally inactivated in mesenchymal progenitor cells (Prx1-cre), pre-osteoblasts (Runx2-cre), and late osteoblasts/osteocytes (Dmp1-cre), respectively.

Revision Surgery After Cartilage Repair: Data From the German Cartilage Registry (KnorpelRegister DGOU).

Background: Various operative strategies have been introduced to restore the integrity of articular cartilage when injured. The frequency of revision surgery after cartilage regenerative surgery remains incompletely understood.

Purpose/hypothesis: The purpose of this study was to identify the reasons for revision surgery after cartilage regenerative surgery of the knee.

Arthroscopic patellar release for treatment of chronic symptomatic patellar tendinopathy: long-term outcome and influential factors in an athletic population.

Background: Arthroscopic patellar release (APR) is utilized for minimally invasive surgical treatment of patellar tendinopathy. Evidence regarding long-term success following the procedure is limited. Also, the influence of age and preoperative performance level, are incompletely understood.

Prospective Clinical Trial for Septic Arthritis: Cartilage Degradation and Inflammation Are Associated with Upregulation of Cartilage Metabolites.

. Intra-articular infections can rapidly lead to osteoarthritic degradation. The aim of this clinical biomarker analysis was to investigate the influence of inflammation on cartilage destruction and metabolism.

Return to Sports Activity and Work After Autologous Chondrocyte Implantation of the Knee: Which Factors Influence Outcomes?

Background: Autologous chondrocyte implantation (ACI) has been associated with satisfying results in everyday activities. Clinical results after ACI treatment of femorotibial lesions are superior in comparison with patellofemoral lesions. There is limited information regarding at which level recreational, amateur, and professional athletes can resume sports and physical activities as well as work after ACI and what parameters influence return to work and sports.

Impaired bone remodeling and its correction by combination therapy in a mouse model of mucopolysaccharidosis-I.

Mucopolysaccharidosis-I (MPS-I) is a lysosomal storage disease (LSD) caused by inactivating mutations of IDUA, encoding the glycosaminoglycan-degrading enzyme α-l-iduronidase. Although MPS-I is associated with skeletal abnormalities, the impact of IDUA deficiency on bone remodeling is poorly defined. Here we report that Idua-deficient mice progressively develop a high bone mass phenotype with pathological lysosomal storage in cells of the osteoblast lineage.

Clinical outcome and return to work following single-stage combined autologous chondrocyte implantation and high tibial osteotomy.

Purpose: Concomitant unloading procedures, such as high tibial osteotomy (HTO), are increasingly recognized as an important part of cartilage repair. This study presents survival rate, functional outcome, complication rate, and return to work following combined single-stage autologous chondrocyte implantation (ACI) and HTO.

Methods: Forty patients with a mean follow-up of 60 months with isolated full thickness cartilage defects of the medial femoral condyle (MFC) and concomitant varus deformity were included in this retrospective case series.

First-generation versus second-generation autologous chondrocyte implantation for treatment of cartilage defects of the knee: a matched-pair analysis on long-term clinical outcome.

Purpose: Since the introduction of autologous chondrocyte implantation (ACI) for the treatment of cartilage defects, the initial technique has undergone several modifications. Whereas an autologous periosteum flap was used for defect coverage in first generation ACI, a standardized collagen membrane was utilized in second generation ACI. To date, however, no study has proven the superiority of this modification in terms of long-term clinical outcome.

Correlation of synovial cytokine expression with quality of cells used for autologous chondrocyte implantation in human knees.

The cell quality plays a decisive role in autologous chondrocyte implantation (ACI). Aim of the study was the analysis of in vivo interactions between synovial concentrations of cytokines and cell quality used for ACI. Knee lavage fluids of patients undergoing an ACI were examined for total protein content (TPC) and by ELISA for levels of basic fibroblast growth factor (bFGF), insulin-like growth factor 1, bone morphogenetic proteins 2 and 7 (BMP-2 and BMP-7).

Posterior root tears of the lateral meniscus.

Purpose: To summarize and discuss the current knowledge on posterior lateral meniscus root tears.

Methods: A comprehensive review of the MEDLINE database was carried out to identify relevant articles using different keywords (e.g.

Simultaneous avulsion fracture of the posterior medial and posterior lateral meniscus root: a case report and review of the literature.

Injuries of the meniscus roots are increasingly recognized as a serious knee joint pathology. An avulsion fracture of the meniscus root is a rare variant of this injury pattern. In this article, a case of a traumatic simultaneous avulsion fracture of both the posterior medial and posterior lateral meniscus root associated with a tear of the anterior cruciate ligament is presented.

Prospective 5-year survival rate data following open-wedge valgus high tibial osteotomy.

Purpose: Open-wedge high tibial osteotomy using internal plate fixation is a well-established and frequently performed treatment option for the management of medial compartment osteoarthritis (OA) in the young and active patients. The present study provides survival rate and functional outcome preoperatively and after 6, 12, 24, 36 and 60 months following open-wedge high tibial osteotomy. Hypothesis of the authors was high survival rates after 5 years with still remaining satisfying functional results.

Clinical outcomes after cell-seeded autologous chondrocyte implantation of the knee: when can success or failure be predicted?

Background: Autologous chondrocyte implantation (ACI) has been associated with satisfying results. Still, it remains unclear when success or failure after ACI can be estimated.

Purpose: To evaluate the clinical outcomes of cell-seeded collagen matrix-supported ACI (ACI-Cs) for the treatment of cartilage defects of the knee at 36 months and to determine a time point after ACI-Cs at which success or failure can be estimated.

Decreased bone formation and increased osteoclastogenesis cause bone loss in mucolipidosis II.

Mucolipidosis type II (MLII) is a severe multi-systemic genetic disorder caused by missorting of lysosomal proteins and the subsequent lysosomal storage of undegraded macromolecules. Although affected children develop disabling skeletal abnormalities, their pathogenesis is not understood. Here we report that MLII knock-in mice, recapitulating the human storage disease, are runted with accompanying growth plate widening, low trabecular bone mass and cortical porosity.

CLCN7 and TCIRG1 mutations differentially affect bone matrix mineralization in osteopetrotic individuals.

Osteopetrosis is an inherited disorder of impaired bone resorption, with the most commonly affected genes being CLCN7 and TCIRG1, encoding the Cl(-) /H(+) exchanger CLC-7 and the a3 subunit of the vacuolar H(+) -ATPase, respectively. We and others have previously shown that the disease is frequently accompanied by osteomalacia, and that this additional pathology is also found in Tcirg1-deficient oc/oc mice. The remaining question was whether osteoid enrichment is specifically associated with TCIRG1 inactivation, or whether CLCN7 mutations would also cause skeletal mineralization defects.

Metaphyseal bone formation induced by a new injectable β-TCP-based bone substitute: a controlled study in rabbits.

Purpose: Adequate filling of bone defects still poses a challenge in every day clinical work. As many bone defects are irregularly shaped the need for appropriate scaffolds reaching the complete defect surface are great. The purpose of this pre-clinical pilot study was to investigate the handling, biocompatibility, biodegradation and osteoconductivity of a new pasty bone substitute (pure phase β-TCP, hyaluronic acid, methylcellulose) in bone tissue.

Bioreactor-Induced Chondrocyte Maturation Is Dependent on Cell Passage and Onset of Loading.

Objective: To explore the effect of shifting in vitro culture conditions regarding cellular passage and onset of loading within matrix-associated bovine articular chondrocytes cultured under free-swelling and/or dynamical loading conditions on general chondrocyte maturation.

Methods: Primary or passage 3 bovine chondrocytes were seeded in fibrin-polyurethane scaffolds. Constructs were cultured either free-swelling for 2 or 4 weeks, under direct mechanical loading for 2 or 4 weeks, or free swelling for 2 weeks followed by 2 weeks of loading.

A non-randomized controlled clinical trial on autologous chondrocyte implantation (ACI) in cartilage defects of the medial femoral condyle with or without high tibial osteotomy in patients with varus deformity of less than 5°.

Purpose: High tibial osteotomy (HTO) is a recommended concomitant surgery when treating cartilage lesions of the medial femoral condyle (MFC). Varus deformities of 5° and more were considered an indication for HTO in patients with cartilage defects. This study compares clinical outcome in patients with ACI and concomitant varus deformity of <5° with or without additional HTO.

Low turnover osteoporosis in sheep induced by hypothalamic-pituitary disconnection.

The hypothalamus is of critical importance in regulating bone remodeling. This is underscored by the fact that intracerebroventricular-application of leptin in ewe leads to osteopenia. As a large animal model of osteoporosis, this approach has some limitations, such as high technical expenditure and running costs.

Paget disease of the spine: an evaluation of 101 patients with a histomorphometric analysis of 29 cases.

Introduction: Paget's disease of bone (PDB) is the second most frequent metabolic bone disease with the spine being a common site of manifestation. Still, neither the disease's etiology nor reasons for its manifestation at preferred skeletal sites are understood. The aim of the current study was therefore to perform a histologic and histomorphometric analysis of PBD biopsies of the spine to achieve a more detailed understanding concerning PDB activity and characteristics.

Influence of cell quality on clinical outcome after autologous chondrocyte implantation.

Background: Several factors influence clinical outcome after autologous chondrocyte implantation (ACI) for the treatment of cartilage defects of the knee joint.

Hypothesis/purpose: The aim of the present study was to investigate the influence of cell quality on clinical outcome after ACI. The hypothesis of the authors was that cell quality at the time of transplantation influences clinical outcome after ACI for cartilage defects.

Clinical outcome of autologous chondrocyte implantation for failed microfracture treatment of full-thickness cartilage defects of the knee joint.

Background: Although various factors have been identified that influence outcome after autologous chondrocyte implantation (ACI), the relevance of prior treatment of the cartilage defect and its effect concerning the outcome of second-line ACI have not been evaluated to a full extent.

Hypothesis: Autologous chondrocyte implantation used as a second-line treatment after failed arthroscopic microfracturing is associated with a higher failure rate and inferior clinical results compared with ACI as a first-line treatment.

Study Design: Cohort study; Level of evidence, 3.

Autologous chondrocyte implantation for treatment of cartilage defects of the knee: what predicts the need for reintervention?

Background: Autologous chondrocyte implantation (ACI) is a well-established treatment option for isolated cartilage defects of the knee joint, providing satisfying outcome. However, cases of treatment failure with the need for surgical reintervention are reported; typical patient's individual and environmental risk factors have previously not been described.

Hypothesis: The need for reintervention after ACI is associated with specific preoperative detectable individual risk factors.