[Supracondylar humeral fractures in childhood]. / Suprakondyläre Humerusfraktur im Kindesalter.

The classification of supracondylar humeral fractures in German-speaking areas is carried out according to von Laer, which has been appropriated from the AO system and has the advantage that it can be used to derive the treatment. When indicated immediate surgery is given preference over a delayed treatment. The result is controlled by functional tests directly during the operation. Instability of the fracture and correct placement of the Kirschner (K) wires are challenging. Alternatives are an external fixator and elastically stable intramedullary nailing (ESIN). Concomitant injuries initially affect the median nerve and the brachial artery and secondarily the radial nerve. Lesions of the ulnar nerve are mostly a postoperative complication. The bony consolidation is achieved after 3-4 weeks and afterwards implant removal can be safely carried out. Embedded K­wires and ESIN are removed after 3-6 months, depending on the surgical capacity and complaints of the patient.

Assessment of pharmacokinetics for microvessel proliferation by DCE-MRI for early detection of physeal bone bridge formation in an animal model.

OBJECTIVES: Bone bridge formation occurs after physeal lesions and can lead to growth arrest if not reversed. Previous investigations on the underlying mechanisms of this formation used histological methods. Therefore, this study aimed to apply a minimally invasive method using dynamic contrast-enhanced MRI (DCE-MRI). MATERIALS AND METHODS: Changes in functional parameters related to the microvessel system were assessed in a longitudinal study of a cohort of an animal model applying a reference region model. The development of morphology of the injured physis was investigated with 3D high-resolution MRI. To acquire complementary information for MRI-related findings qRT-PCR and immunohistochemical data were acquired for a second cohort of the animal model. RESULTS: The evaluation of the pharmacokinetic parameters showed a first rise of the transfer coefficient 7 days post-lesion and a maximum 42 days after operation. The analysis of the complementary data showed a connection of the first rise to microvessel proliferation while the maximum value was linked to bone remodeling. CONCLUSION: The pharmacokinetic analysis of DCE-MRI provides information on a proliferation of microvessels during the healing process as a sign for bone bridge formation. Thereby, DCE-MRI could identify details, which up to now required analyses of highly invasive methods.

The origin points of the knee collateral ligaments: an MRI study on paediatric patients during growth.

PURPOSE: Different femoral origins for both the medial collateral ligament (MCL) and the lateral collateral ligament (LCL) have been reported in the growing skeleton (epiphyseal and metaphyseal). Knowledge about the exact attachment sites is mandatory for anatomically correct reconstruction. This study assesses the femoral origins of the knee collateral ligaments in skeletally immature individuals using magnetic resonance imaging (MRI). METHODS: MRIs of 336 knee joints (median age 15 years (range 2-18 years), m = 209 and f = 127) were retrospectively analysed to assess the distances between the femoral origins of the MCL and LCL to the distal femoral growth plate. In 175 patients, the body sizes were additionally retrieved from medical records. RESULTS: Both MCL and LCL ligament origins were invariably located on the epiphysis. Mean MCL origin-growth plate distance was 9.6 mm (SD 2.1 mm; range 2.2-13.6 mm) in boys and 8.6 mm (SD 1.5 mm; range 3.4-12.0 mm) in girls. Mean LCL origin-growth plate distance was 9.3 mm (SD 1.8 mm; range 4.3-13.0 mm) in boys and 8.2 mm (SD 1.5 mm; range 3.4-11.8 mm) in girls. The distance between the growth plate and both collateral ligaments as well as the length of the LCL correlated positively with patients' age and body size (MCL R(2) = 0.673 and 0.556, LCL R (2) = 0.734 and 0.645, LCL length R(2) = 0.589 and 0.741; all p < 0.001). CONCLUSIONS: During growth, the femoral origins of the MCL and the LCL are constantly located on the distal femoral epiphysis. There is a linear increase in the distances from the ligaments' origins to the growth plate according to age and body size. This new information may be of clinical importance for reconstructive surgery of the knee's collateral ligaments.

Biomarkers of Chondrocyte Apoptosis and Autophagy in Osteoarthritis.

Cell death with morphological and molecular features of apoptosis has been detected in osteoarthritic (OA) cartilage, which suggests a key role for chondrocyte death/survival in the pathogenesis of OA. Identification of biomarkers of chondrocyte apoptosis may facilitate the development of novel therapies that may eliminate the cause or, at least, slow down the degenerative processes in OA. The aim of this review was to explore the molecular markers and signals that induce chondrocyte apoptosis in OA. A literature search was conducted in PubMed, Scopus, Web of Science and Google Scholar using the keywords chondrocyte death, apoptosis, osteoarthritis, autophagy and biomarker. Several molecules considered to be markers of chondrocyte apoptosis will be discussed in this brief review. Molecular markers and signalling pathways associated with chondroycte apoptosis may turn out to be therapeutic targets in OA and approaches aimed at neutralizing apoptosis-inducing molecules may at least delay the progression of cartilage degeneration in OA.

Towards a better understanding of bone bridge formation in the growth plate - an immunohistochemical approach.

The growth plate at the end of long bones is the cartilaginous organ responsible for longitudinal bone growth in children. Trauma to the growth plate, i.e. fractures, can severely impair longitudinal bone growth, leading to growth disorders due to destruction of the epiphyseal circulation and formation of a bone bridge. From the clinical experience it is known that in some patients this bone bridge eventually disappears during the growth process. However, the molecular mechanisms involved in bone bridge formation and dissolution have not been clarified yet. The aim of this study was to investigate the spatial and temporal protein level of molecules potentially involved in these processes, i.e. RANKL, OPG, DKK-1, Coll 10, BMP-2 and IL-6, in an experimental rat model using an immunohistochemical approach. The results from our study suggest that bone bridge formation might be an early event starting immediately after growth plate injury and involving several pro-osteoblastic molecules, i.e. IL-6, BMP-2 as well as OPG and Coll X. In the late studied time points 3- and 9-month post-injury expression of anti-osteoblastic proteins, i.e. DKK1 and RANKL, was increased. This indicates that bone bridge dissolution might be a late event and potentially linked to Wnt signaling inhibition and RANK/RANKL signaling activation.

The effects of physical activity on apoptosis and lubricin expression in articular cartilage in rats with glucocorticoid-induced osteoporosis.

Glucocorticoids are considered the most powerful anti-inflammatory and immunomodulating drugs. However, a number of side-effects are well documented in different diseases, including articular cartilage, where increases or decreases in the synthesis of hormone-dependent extracellular matrix components are seen. The objective of this study has been to test the effects of procedures or drugs affecting bone metabolism on articular cartilage in rats with prednisolone-induced osteoporosis and to evaluate the outcomes of physical activity with treadmill and vibration platform training on articular cartilage. The animals were divided into 5 groups, and bone and cartilage evaluations were performed using whole-body scans and histomorphometric analysis. Lubricin and caspase-3 expression were evaluated by immunohistochemistry, Western blot analysis and biochemical analysis. These results confirm the beneficial effect of physical activity on the articular cartilage. The effects of drug therapy with glucocorticoids decrease the expression of lubricin and increase the expression of caspase-3 in the rats, while after physical activity the values return to normal compared to the control group. Our findings suggest that it might be possible that mechanical stimulation in the articular cartilage could induce the expression of lubricin, which is capable of inhibiting caspase-3 activity, preventing chondrocyte death. We can assume that the physiologic balance between lubricin and caspase-3 could maintain the integrity of cartilage. Therefore, in certain diseases such as osteoporosis, mechanical stimulation could be a possible therapeutic treatment. With our results we can propose the hypothesis that physical activity could also be used as a therapeutic treatment for cartilage disease such as osteoarthritis.

Post-traumatic caspase-3 expression in the adjacent areas of growth plate injury site: a morphological study.

The epiphyseal plate is a hyaline cartilage plate that sits between the diaphysis and the epiphysis. The objective of this study was to determine the impact of an injury in the growth plate chondrocytes through the study of histological morphology, immunohistochemistry, histomorphometry and Western Blot analyses of the caspase-3 and cleaved PARP-1, and levels of the inflammatory cytokines, Interleukin-6 (IL-6) and Tumor Necrosis Factor alpha (TNF-α), in order to acquire more information about post-injury reactions of physeal cell turnover. In our results, morphological analysis showed that in experimental bones, neo-formed bone trabeculae-resulting from bone formation repair-invaded the growth plate and reached the metaphyseal bone tissue (bone bridge), and this could result in some growth arrest. We demonstrated, by ELISA, increased expression levels of the inflammatory cytokines IL-6 and TNF-α. Immunohistochemistry, histomorphometry and Western Blot analyses of the caspase-3 and cleaved PARP-1 showed that the physeal apoptosis rate of the experimental bones was significantly higher than that of the control ones. In conclusion, we could assume that the inflammation process causes stress to chondrocytes that will die as a biological defense mechanism, and will also increase the survival of new chondrocytes for maintaining cell homeostasis. Nevertheless, the exact stimulus leading to the increased apoptosis rate, observed after injury, needs additional research to understand the possible contribution of chondrocyte apoptosis to growth disturbance.

Newly Developed Resorbable Magnesium Biomaterials for Orbital Floor Reconstruction in Caprine and Ovine Animal Models-A Prototype Design and Proof-of-Principle Study.

BACKGROUND: orbital floor fractures have not been reconstructed using magnesium biomaterials. METHODS: To test technical feasibility, ex vivo caprine and ovine heads (n = 5) were used. Head tissues were harvested from pubescent animals (n = 5; mean age: 3.2 years; mean mass: 26.3 kg) and stored below 11 degrees for 7-10 days. All procedures were performed in a university animal resource facility. Two experienced maxillofacial surgeons performed orbital floor procedures in both orbits of all animals in a step-by-step preplanned dissection. A transconjunctival approach was chosen to repair the orbital floor with three different implants (i.e., magnesium implants; titanium mesh; and polydioxanone or PDO sheets). The position of each implant was evaluated by Cone-beam computed tomography (CBCT). RESULTS: Axial, coronal, and sagittal plane images showed good positioning of the magnesium plates. The magnesium plates had a radiographic visibility similar to that of the PDO sheets but lower than that of the titanium mesh. CONCLUSIONS: The prototype design study showed a novel indication for magnesium biomaterials. Further testing of this new biomaterial may lead to the first resorbable biomaterial with good mechanical properties for extensive orbital wall defects.

Degradation behavior and osseointegration of Mg-Zn-Ca screws in different bone regions of growing sheep: a pilot study.

Magnesium (Mg)-based implants are highly attractive for the orthopedic field and may replace titanium (Ti) as support for fracture healing. To determine the implant-bone interaction in different bony regions, we implanted Mg-based alloy ZX00 (Mg < 0.5 Zn < 0.5 Ca, in wt%) and Ti-screws into the distal epiphysis and distal metaphysis of sheep tibiae. The implant degradation and osseointegration were assessed in vivo and ex vivo after 4, 6 and 12 weeks, using a combination of clinical computed tomography, medium-resolution micro computed tomography (µCT) and high-resolution synchrotron radiation µCT (SRµCT). Implant volume loss, gas formation and bone growth were evaluated for both implantation sites and each bone region independently. Additionally, histological analysis of bone growth was performed on embedded hard-tissue samples. We demonstrate that in all cases, the degradation rate of ZX00-implants ranges between 0.23 and 0.75 mm/year. The highest degradation rates were found in the epiphysis. Bone-to-implant contact varied between the time points and bone types for both materials. Mostly, bone-volume-to-total-volume was higher around Ti-implants. However, we found an increased cortical thickness around the ZX00-screws when compared with the Ti-screws. Our results showed the suitability of ZX00-screws for implantation into the distal meta- and epiphysis.

The influence of ultrasound guidance in the rate of success of acromioclavicular joint injection: an experimental study on human cadavers.

BACKGROUND: Injections of the acromioclavicular joint (ACJ) are performed routinely in patients with ACJ arthritis, both diagnostically and therapeutically. The aim of this prospective controlled study was to estimate the frequency of successful intra-articular ACJ injections with the aid of sonographic guidance versus non-guided ACJ injections. MATERIALS AND METHODS: A total of 80 cadaveric ACJs were injected with a solution containing methylene blue and subsequently dissected to distinguish intra- from peri-articular injections. In 40 cases the joint was punctured with sonographic guidance, whereas 40 joints were injected in the control group without the aid of ultrasound. RESULTS: The rate of successful intra-articular ACJ injection was 90% (36 of 40) in the guided group and 70% (28 of 40) in the non-guided group. Ultrasound was significantly more accurate for correct intra-articular needle placement (P = .025). DISCUSSION: The use of ultrasound significantly improves the accuracy of ACJ injection.

Accuracy of anterolateral versus posterolateral subtalar injection.

INTRODUCTION: Injections into the subtalar joint may be performed for diagnostic or therapeutic reasons. The anterolateral approach is most commonly utilised for this purpose. We evaluated the success of an intra-articular puncture by using the anterolateral in comparison to the posterolateral approach. METHODS: Sixty-eight cadaver adult feet were used for performing injections into the subtalar joint without fluoroscopic or ultrasound guidance. Methylene blue dye was infiltrated into 34 of the 68 subtalar joints through an anterolateral approach and into 34 through an posterolateral approach. An arthrotomy was then performed to confirm the placement of the dye within the joint. RESULTS: Twenty-three of the anterolateral injections (67.6%) were successful as were 31 of 34 (91.2%) of the posterolateral. The posterolateral approach showed a greater accuracy with a statistically significance (p = 0.016). CONCLUSION: Unintended peri-articular injection can cause complications and an unsuccessful aspiration can delay diagnosis. Comparing the anterolateral to the posterolateral approach with regards to the rate of successful intra-articular puncture of the subtalar joint without the use of imaging there is a greater accuracy with the PL with statistically significance.

A 3-Dimensional In Vitro Model of Zonally Organized Extracellular Matrix.

OBJECTIVE: Functional cartilage repair requires the new formation of organized hyaline cartilaginous matrix to avoid the generation of fibrous repair tissue. The potential of mesenchymal progenitors was used to assemble a 3-dimensional structure in vitro, reflecting the zonation of collagen matrix in hyaline articular cartilage. DESIGN: The 3-dimensional architecture of collagen alignment in pellet cultures of chondroprogenitors (CPs) was assessed with Picrosirius red staining analyzed under polarized light. In parallel assays, the trilineage capability was confirmed by calcium deposition during osteogenesis by alizarin S staining and alkaline phosphatase staining. Using reverse transcription-quantitative polymerase chain reaction (RT-qPCR), mRNA levels of ALP, RUNX2, and BGLAP were assessed after 21 days of osteoinduction. Lipid droplets were stained with oil red O and adipogenic differentiation was confirmed by RT-qPCR analysis of PPARG and LPL gene expression. RESULTS: Under conditions promoting the chondrogenic signature in self-assembling constructs, CPs formed an aligned extracellular matrix, positive for glycosaminoglycans and collagen type II, showing developing zonation of birefringent collagen fibers along the cross section of pellets, which reflect the distribution of collagen fibers in hyaline cartilage. Induced osteogenic and adipogenic differentiation confirmed the trilineage potential of CPs. CONCLUSION: This model promotes the differentiation and self-organization of postnatal chondroprogenitors, resulting in the formation of zonally organized engineered hyaline cartilage comparable to the 3 zones of native cartilage.

Influence of high-pressure torsion deformation on the corrosion behaviour of a bioresorbable Mg-based alloy studied by positron annihilation.

The effect of high-pressure torsion (HPT) on the corrosion behavior of extruded ZX00 (Mg-0.45wt%Zn-0.45wt%Ca) in phosphate buffered saline solution is investigated. MgCaZn alloys are promising candidates for the use as bioresorbable implant materials and, therefore, are in the focus of current research. To improve their strength, severe plastic deformation, e.g. via the technique of HPT, can be used. Positron lifetime spectroscopy (PLS) is applied as sensitive tool for studying open-volume defects which evolve during HPT processing and subsequent corrosion. The studies were complemented by electrochemical impedance spectroscopy (EIS). In the uncorroded state, grain boundaries are the major type of positron trap as quantitatively analysed by means of diffusion-reaction models for positron trapping and annihilation in fine-grained alloys. Upon corrosion, positronium formation and annihilation indicate larger open-volume structures, such as pores and cracks, in the emerging corrosion product and oxide layers. Both PLS and EIS clearly show that HPT-deformation strongly reduces the resistance against corrosion. Evidence is found for corrosion-induced open-volume defects, presumably related to hydrogen, in deeper parts of the material below the corrosion layer.

[Quality improvement of postoperative pain management in infants QUIPSI) - A pilot study]. / QUIPSI - Qualitätsverbesserung der postoperativen Schmerztherapie bei Kindern.

Outcome-focussed benchmarking has been shown to be a successful tool in adult quality improvement of postoperative pain management in adults. We report on feasibility and first results of a similar project in operated children (quality improvement of postoperative pain management in infants, QUIPSI). Our results show that outcomes in postoperative pain management can be measured and compared in routine clinical practice. QUIPSI (Quality Improvement in Postoperative Pain Management in Infants) represents a new tool for outcome evaluation, consisting of standardized data acquisition of outcome and process quality indicators. In the currently starting second phase of the project, a multicenter evaluation will take place in ten medical centres.

A lean magnesium-zinc-calcium alloy ZX00 used for bone fracture stabilization in a large growing-animal model.

Over the last decade, demand has increased for developing new, alternative materials in pediatric trauma care to overcome the disadvantages associated with conventional implant materials. Magnesium (Mg)-based alloys seem to adequately fulfill the vision of a homogeneously resorbable, biocompatible, load-bearing and functionally supportive implant. The aim of the present study is to introduce the high-strength, lean alloy Mg‒0.45Zn‒0.45Ca, in wt% (ZX00), and for the first time investigate the clinical applicability of screw osteosynthesis using this alloy that contains no rare-earth elements. The alloy was applied in a growing sheep model with osteotomized bone (simulating a fracture) and compared to a non-osteotomy control group regarding degradation behavior and fracture healing. The alloy exhibits an ultimate tensile strength of 285.7 ± 3.1 MPa, an elongation at fracture of 18.2 ± 2.1%, and a reduced in vitro degradation rate compared to alloys containing higher amounts of Zn. In vivo, no significant difference between the osteotomized bone and the control group was found regarding the change in screw volume over implantation time. Therefore, it can be concluded that the fracture healing process, including its effects on the surrounding area, has no significant influence on degradation behavior. There was also no negative influence from hydrogen-gas formation on fracture healing. Despite the proximal and distal screws showing chronologically different gas release, the osteotomy showed complete consolidation. STATEMENT OF SIGNIFICANCE: Conventional implants involve several disadvantages in pediatric trauma care. Magnesium-based alloys seem to overcome these issues as discussed in the recent literature. This study evaluates the clinical applicability of high-strength lean Mg‒0.45Zn‒0.45Ca (ZX00) screws in a growing-sheep model. Two groups, one including a simulated fracture and one group without fracture, underwent implantation of the alloy and were compared to each other. No significant difference regarding screw volume was observed between the groups. There was no negative influence of hydrogen-gas formation on fracture healing and a complete fracture consolidation was found after 12 weeks for all animals investigated.

Chondrocyte apoptosis enhanced at the growth plate: a physeal response to a diaphyseal fracture.

Post-traumatic overgrowth of growing long bones is a common clinical phenomenon in paediatric traumatology and is the result of an enhanced stimulation of the nearby growth plate after fracture. To date, the exact post-fractural reactions of the growth plate are poorly understood. The aim of this study has been to determine the impact of fracture on the frequency of chondrocyte apoptosis of the growth plate. Rats sustained a mid-diaphyseal closed fracture of the left tibia or were left untreated. All animals were killed 3, 10, 14 or 29 days after trauma. The left and right tibiae were harvested and apoptotic chondrocytes of the proximal tibial growth plate were detected by TUNEL staining. The apoptosis percentage of physeal chondrocytes was statistically compared among fractured bones, intact contra-lateral bones and control bones. The physeal apoptosis rate of the fractured bone was significantly higher than that of the contra-lateral intact bone (valid for all evaluated days) and the control bone (valid from day 10 onwards). Contra-lateral intact tibiae never showed significantly higher apoptosis rates compared with control tibiae. Thus, mid-diaphyseal fracture influences the nearby growth plate by stimulating chondrocyte programmed cell death, which is associated with cartilage resorption and bone replacement. The lack of a significant difference between the intact contra-lateral and the intact control bone suggests that fracture only has a local effect that contributes to the greater apoptosis rate of the adjacent physis.

Transitional fractures of the distal tibia: a minimal access approach for osteosynthesis.

BACKGROUND: Transitional fractures typically occur in patients with partially closed growth plates. In case of displacements >2 mm, osteosynthesis is recommended. Open reduction and stabilization with lag screws is the most common approach. Infection and paraesthesia are common complications of this method. This study describes an alternative approach by closed reduction and cannulated screw fixation. METHODS: All patients with transitional fractures treated by closed reduction and cannulated screw fixation were identified. All patients with >1 year after implant removal were included in this investigation. Of 27 patients treated by this technique, 21 met the inclusion criteria and were sent a standardized questionnaire including the Foot Function Index (FFI). All cases with impairments in the FFI were invited for a follow-up examination. RESULTS: Postoperative complications occurred in two patients (8.3%): one reported paraesthesia of the hallux and one showed skin irritations above the screw insertion. Average follow-up time was 3.8 years after implant removal. Of 21 patients who returned the questionnaire, three patients (14.3%) had impairment in the FFI and were invited for clinical follow-up: one patient showed mild signs of osteoarthritis without visible gaps of the joint surface, one patient had minimally restricted pronation, and one had neither clinical nor radiologic correlates for the impairment reported. Sports activity was reduced in one patient. CONCLUSION: If closed reduction can be achieved fixation with cannulated screws proved to be a satisfactory method with little scars and good clinical results.

A 300 µm Organotypic Bone Slice Culture Model for Temporal Investigation of Endochondral Osteogenesis.

Translational studies to elucidate the response of immature bone to biologic and physical stimuli have been held back by the lack of a viable long-term functional bone explant model. This study attempts to bridge this gap between cell culture and animal model studies. In this study, we describe a methodology to derive a 300 µm organotypic femur slice comprising physiological zones (epiphysis and meta-diaphysis) essential for endochondral bone development. The unique capability of slice culture model incorporating enhanced nutrient access to distinct bone tissue components associated with linear bone growth facilitates the investigation of the orchestrated cellular transition of chondrogenic and osteogenic cells involved in endochondral bone development in an ex vivo setup. Bone slices of 300 µm were prepared from 4-day-old postnatal rats and were viable in culture up to 21 days. On days 7 and 15, an increase in chondrogenic and osteogenic modulations was confirmed in epiphysis, metaphysis, and diaphysis. An increase in osteocytes, osteoblasts, and hypertrophic cells were found at these time points, as well as a noticeable increased expression of chondrogenic and osteogenic markers (collagen II, Runx2, and osteocalcin) confirmed endochondral progression. Osteoclast-mediated bone resorption was demonstrated on day 15 by tartrate-resistant acid phosphatase staining. Attenuated total reflection infrared spectroscopic analyses, furthermore, confirmed a time-dependent increase in phosphate levels, bone minerals, and hydroxyapatite for 15 days. Our establishment of a bone slice culture model closely mimicking the in vivo cellular transitions and endochondral microenvironment of a mineralizing bone provides a vital new tool for the elucidation of cellular and endochondral mechanisms of bone development, maturation, and growth plate modulations. The presented model has the potential to be utilized in implementation of preclinical, toxicological, and therapeutic investigations.