Gas-phase production and photoelectron spectroscopy of the smallest fullerene, C20

Fullerenes are graphitic cage structures incorporating exactly twelve pentagons. The smallest possible fullerene is thus C20, which consists solely of pentagons. But the extreme curvature and reactivity of this structure have led to doubts about its existence and stability. Although theoretical calculations have identified, besides this cage, a bowl and a monocyclic ring isomer as low-energy members of the C20 cluster family, only ring isomers of C20 have been observed so far. Here we show that the cage-structured fullerene C20 can be produced from its perhydrogenated form (dodecahedrane C20H20) by replacing the hydrogen atoms with relatively weakly bound bromine atoms, followed by gas-phase debromination. For comparison we have also produced the bowl isomer of C20 using the same procedure. We characterize the generated C20 clusters using mass-selective anion photoelectron spectroscopy; the observed electron affinities and vibrational structures of these two C20 isomers differ significantly from each other, as well as from those of the known monocyclic isomer. We expect that these unique C20 species will serve as a benchmark test for further theoretical studies.

On the challenge of estimating diphoton backgrounds at large invariant mass.

We examine, using the analyses of the 750 GeV diphoton resonance as a case study, the methodology for estimating the dominant backgrounds to diphoton resonance searches. We show that close to the high energy tails of the distributions, where background estimates rely on functional extrapolations or Monte Carlo predictions, large uncertainties are introduced, in particular by the challenging photon-jet background. Analyses with loose photon and low photon [Formula: see text] cuts and those susceptible to high photon rapidity regions are especially affected. Given that diphoton-based searches beyond 1 TeV are highly motivated as discovery modes, these considerations are relevant for future analyses. We first consider a physics-driven deformation of the photon-jet spectrum by next-to-leading order effects and a phase space dependent fake rate and show that this reduces the local significance of the excess. Using a simple but more general ansatz, we demonstrate that the originally reported local significances of the 750 GeV excess could have been overestimated by more than one standard deviation. We furthermore cross-check our analysis by comparing fit results based on the 2015 and 2016 LHC data sets. Finally we employ our methodology on the available 13 TeV LHC data set assessing the systematics involved in the current diphoton searches beyond the TeV region.

Systemic application of growth hormone enhances the early healing phase of osteochondral defects--a preliminary study in micropigs.

Healing of osteochondral defects following trauma remains a significant clinical problem, often leading to osteoarthritis. Growth hormone (GH) has been shown to accelerate formation of bone and cartilage tissue in the growth plates and in cell cultures. To investigate the influence of systemically administered recombinant porcine growth hormone (r-pGH) on the healing of osteochondral defects we performed a histomorphometrical analysis of full-thickness cartilage defects in the femoral condyle of micropigs. Forty-eight mature female Yucatan micropigs were divided into two groups, one receiving a daily injection of r-pGH (100 microg/kg), the other receiving sodium chloride as placebo. A circular 6-mm-diameter full-thickness defect of the cartilage was created, extending 1.5 mm into the subchondral bone. The animals were sacrificed after 4 (n = 24) and 6 (n = 24) weeks. The von-Kossa stain was used to visualise the calcified structures; cartilage and the fibrous tissue were marked with a combined Safranin-O/light-green stain. The defect filling and the percentage of bone, cartilage, and fibrous tissue into the defect were evaluated using an image analysis system. Furthermore, histological grading was performed using the modified Wakitani score. After 4 weeks no differences were observed between both groups. The defect filling after 6 weeks with newly formed bone was significantly higher in the r-pGH-treated group. The formation of cartilage and fibrous tissue showed a trend towards better healing in the GH-treated group; however, there was no significant difference. In the r-pGH-treated group, the percentage of total defect filling was significantly higher. The evaluation of the vascularity showed a significantly lower number of vessels in the GH-treated group after 6 weeks. Histomorphological grading revealed a significantly lower total Wakitani score in the GH-treated group, which represents a better healing result compared to the controls. The results of the present study suggest that circulating r-pGH or one of its mediators may accelerate osteochondral defect healing by stimulating the formation of osseous and chondral tissue. The analysis of the vascularity leads to the assumption of an advanced maturation of the osteochondral defects under the influence of GH.

Recombinant growth hormone accelerates bone regenerate consolidation in distraction osteogenesis.

The purpose of the present study was to prove whether homologous GH has a stimulating effect on bone healing. Therefore, left tibiae of 30 micropigs were osteomized and distracted over an external fixator at the rate of 2 mm/day on each of 10 consecutive days. Animals were killed after a healing period of another 10 days. The treatment group received 100 microg of recombinant porcine growth hormone (rpGH) per kilogram of body weight per day. Serial torsional nondestructive biomechanical tests were performed in vivo using a newly developed measurement device. After killing, destructive torsional strength testing of the sites of distraction was performed. To determine the endocrine response to the administration of rpGH, serum levels of insulin-like growth factor-I (IGF-I) were determined. Nondestructive in vivo testing showed that torsional stiffness of the regenerate was significantly higher in the treatment group than in the control group. Final regenerate torsional failure load was 131% higher and ultimate torsional stiffness was 231% higher in the treatment group than in the control group. The mean serum level of IGF-I increased to 440% of preoperative basal level in the treatment group and remained unchanged in the control group. Our data indicate that systemic administration of recombinant homologous growth hormone greatly accelerates ossification of bone regenerate in distraction osteogenesis.

Recombinant species-specific growth hormone increases hard callus formation in distraction osteogenesis.

The effect of growth hormone (GH) on secondary fracture healing and callus formation has been demonstrated in several previously investigated animal models. The aim of this study was to investigate and quantify the effects of GH on bone regenerates in a distraction osteogenesis model. In 20 mature female Yucatan micropigs, the tibia and fibula were osteotomized, stabilized with an external fixator, and distracted at 2 mm/day for 10 days after a 4 day latency period. The regenerates were allowed to consolidate for 10 days. Micropigs in the study group (ten animals) received a daily injection of 100 microg per kilogram body weight of recombinant porcine growth hormone (r-pGH). Micropigs in the control group (ten animals) received sodium chloride as placebo. After killing on day 25, a quantitative histomorphometrical analysis of the formed callus and the adjacent cortical bone was performed and the results of polychrome in vivo labeling were assessed. The regenerates of the r-pGH-treated animals showed a significantly larger callus area but no change in callus structure. We found islands of cartilage tissue in the regenerates of both groups; the calli from the control group exhibited a higher fraction of cartilage compared with the r-pGH group, but this was not significant. Quantification of the fluorescent in vivo labeling revealed that the distraction gap in GH-treated group showed significant ossification even during distraction. These results demonstrate that growth hormone can accelerate the maturation of the regenerate in distraction osteogenesis without changing the callus microstructure. This may prove to be a useful clinical tool for shortening the healing time in limb lengthening and bone segment transport.

A Plasmodium falciparum-specific reverse target capture assay.

Plasmodium falciparum DNA is detected with an assay modeled according to the reverse target capture assay described by Morrissey et al. [19] for the detection of Listeria cells. A poly(A)-tailed oligonucleotide (pWZ34), derived from the partial sequence of a 4-kb repetitive unit of P. falciparum, functions as a capture probe and the labelled 21-bp repetitive units specific for P. falciparum serve as a reporter probe. Both probes are complementary to non-overlapping regions of the target DNA and in the presence of high concentration of chaotropic salts, hybridization efficiently takes place at relatively low temperatures (15 min. 37 degrees C). The addition of poly(dT)-derivatized ferromagnetic beads allows the formation of A:T base pairing between the tailed beads and the tailed capture probe. Upon applying magnetic force, the target-capture-reporter-probe complex attached to the beads is removed from the reaction mixture, leaving the bulk of unreacted reporter molecules behind. Subsequent washings of the immobilized complex reduces the amount of non-specifically bound reporter probe. After elution of the complex from the beads a new cycle of capture, washing and release of the target-capture-reporter-probe complex is initiated by the additions of unused (dT)-tailed beads. After 3 cycles, the signal-to-noise ratio with 0.1 pg of P. falciparum DNA as a target was as high as 21-27, with a background of 8-10 cpm. The assay is unique in its speed, well suited for large sample numbers, and allows the manipulation of the background at will by simply increasing the number of capture rounds.

The immune-enhancing effect of perioperative thymopentin administration in elderly patients undergoing major surgery.

The effects of perioperative administration of thymopentin (TP-5) on in vivo and in vitro measurements of cell-mediated immunity in elderly patients undergoing major surgery were investigated. A placebo-controlled study was conducted in 25 patients (mean age, 67 years) with congenital or acquired heart disease undergoing surgery with cardiopulmonary bypass. Patients were divided into three groups: Group 1 patients were given 50 mg of TP-5 subcutaneously two hours preoperatively. Group 2 patients were given 50 mg of TP-5 subcutaneously two hours preoperatively and 48 hours postoperatively. Group 3 patients were given placebo at corresponding times. Cell-mediated immunity measurements were the in vivo delayed-type hypersensitivity (DTH) response on day 0 and on day 7 to an antigen skin test battery. The in vitro studies included antigen cocktail-induced lymphocyte proliferation of peripheral blood mononuclear cells. The DTH response on day 7 after surgery was significantly suppressed in group 3 patients compared with the preoperative baseline value, while it remained unaltered in group 1 and 2 patients. There was a considerable difference of DTH measurements (number of positive antigen responses and sum of their mean diameters) between group 2 and 3 patients. Antigen cocktail-induced lymphocyte proliferation, following initial suppression in the majority of patients, was significantly different between the placebo group and patients in group 2 on day 7 after surgery. The data indicate that perioperative administration of TP-5 might be of considerable clinical utility in preventing a defective cellular immune response.

The effect of growth hormone on insulin-like growth factor I and bone metabolism in distraction osteogenesis.

Limb lengthening in the left tibia of 30 mature female Yucatan micropigs was performed using distraction osteogenesis. A treatment group of 15 animals received recombinant porcine growth hormone (r-pGH) (100 microg/kg/day) while the others served as controls. Serial serum measurements of total insulin-like growth factor I (IGF-I), free IGF-I, IGF binding proteins -1, -2, -3 and -4 (IGFBP-1 to -4) were performed. Bone-specific alkaline phosphatase (bone-ALP) and the serum carboxyl-terminal telopeptide of type I collagen (ICTP) were measured as bone turnover markers. The GH-treated animals showed a significant increase in total IGF-I, free IGF-I and IGFBP-3 after surgery (P<0.001). Similarly, the treated animals showed a significantly higher level of bone-ALP (P<0.001) throughout the experiment compared to the controls. There was a significant correlation between bone-ALP and total IGF-I (r=0.76) in the GH-treated group and an even higher correlation for free IGF-I (r=0.90). There was no difference in the ICTP serum levels between the two groups. These data indicate that the application of species-specific growth hormone results in a stimulation of bone formation in distraction osteogenesis which may be mediated by IGF-I. The stronger correlation between free IGF-I and bone-ALP indicates that the anabolic effect of IGF-I may be regulated through the IGFBPs by binding and inactivating IGF-I.

Capillary electrophoresis, a rapid and sensitive method for routine analysis of apolipoprotein A-I in clinical samples.

A method for the determination of apolipoprotein A-I, the major protein compartment of HDL, in human serum is described. Rapid and easy serum sample preparation, well separated Apo A-I peaks in the human serum electropherogram and good linearity of the peak area vs. concentration plot, covering the range of the clinically relevant Apo A-I serum contents, suggest the introduction of this method routinely in clinical laboratories.

Capillary electrophoresis in biochemical and clinical laboratoriesp selected attractive examples.

As demonstrated by selected examples from our laboratories, CE is a unique methodology for purity control of synthetic as well as natural tissue-isolated biopolymers, a prerequisite before reliable biotestings should be performed. A combination of rapid matrix-assisted laser desorption ionization mass and CE electrophoretic mobility determinations facilitates primary sequence determinations of enzymatic peptide digest mixtures often making costly Edman degradations unnecessary. The enormous separation efficiency and large variety of different possible separation modes in CE, allow detection of single components in complex mixtures which is demonstrated by the apolipoprotein A-I determination in human blood serum in this communication.

Photodynamic action of uroporphyrin on the complement system in porphyria cutanea tarda.

We investigated the effect of UV light (320-460 nm) on total hemolytic CH50 activity and C3 cleavage in sera obtained from 14 patients with porphyria cutanea tarda. Irradiation with 5, 10, or 50 J/cm2 resulted in a 12%-60% loss of CH50 and a 5%-30% cleavage of native C3 as estimated by planimetric evaluation of the immunoelectrophoretic C3 pattern. The complement changes were most pronounced in sera from patients with active disease and were minimal or absent in patients who were in remission. In all cases, the decrease of CH50 and C3 cleavage was proportional to the plasma-porphyrin concentration and the dose of radiation. After exposure to 320- to 460-nm light, similar changes were seen in normal human serum (NHS) to which exogenous uroporphyrin had been added. Beta-carotene and chloroquine had no inhibitory effect on the photodynamic complement activation. The C3 cleavage in irradiated NHS containing uroporphyrin was not affected by 10 mM EGTA, but was partially inhibited in the presence of 30 mM EDTA, thus indicating that the interaction of photoexcited uroporphyrin with the complement system differs from classical-pathway complement activation.

A new device to quantify regenerate torsional stiffness in distraction osteogenesis.

We present a newly developed torsional stiffness measurement device with the potential to quantitatively assess the in vivo torsional stiffness of bone regenerate during distraction osteogenesis. We describe the form and function of this device and its application in a model of regenerate consolidation. The device was able to produce data to assess stiffness of the regenerate with an accuracy between +/- 3 and +/- 9% for material stiffness ranging between 0.1 and 2.4 Nm/o and with a precision of +/- 3.6%. This method provides advantages over similar methods of bone fracture healing assessment with guaranteed maintenance of bone axis, minimized risk of bone misalignment during the bone healing process and a close relation to the functional loading pattern in torsion of bones such as tibia and femora.

Bisegmental rotational fracture dislocation of the pediatric cervical spine. A case report.

STUDY DESIGN: A case of a bisegmental rotational fracture dislocation in the pediatric cervical spine is presented. OBJECTIVES: To highlight the problems in the diagnostics and surgical management of this rare type of injury. SUMMARY OF BACKGROUND DATA: Fractures of the cervical spine are relatively uncommon in childhood. To the authors' knowledge, this is the first reported case of a bisegmental rotational fracture dislocation in the pediatric cervical spine managed by a combined anteroposterior approach. METHODS: A 6-year-old girl was hit by a car as a pedestrian. In addition to an open fracture dislocation of the Lisfranc joint in the right foot, she sustained a bisegmental fracture dislocation at the lower cervical spine (C3-C5) with no neurologic deficit. The complete diagnosis of a locked rotational fracture dislocation could be established only by using computed tomography scans with three-dimensional reconstructions. The injury was managed with a combined anteroposterior open reduction and a bisegmental anterior fusion. RESULTS: Implant removal was performed after bony fusion 6 months after surgery. At follow-up assessment 2.5 years later, the girl had a good radiologic result and a full and pain-free functional recovery. CONCLUSIONS: Bisegmental rotational fracture dislocations in pediatric cervical spines are not easily diagnosed and may require three-dimensional computed tomography scan reconstructions for complete assessment. In such rare cases, a combined anteroposterior surgical procedure may be indicated, with a bisegmental anterior fusion providing a good functional result.

Graft fixation in cruciate ligament reconstruction.

Cruciate ligament reconstruction has progressed dramatically in the last 20 years. Anatomic placement of ligament substitutes has fostered rehabilitation efforts that stress immediate and full range of motion, immediate weightbearing, neuromuscular strength and coordination, and early return to athletic competition (3 months). This has placed extreme importance on secure graft fixation at the time of ligament reconstruction. Current ligament substitutes require a bony or soft tissue component to be fixed within a bone tunnel or on the periosteum at a distance from the normal ligament attachment site. Fixation devices have progressed from metal to biodegradable and from far to near-normal native ligament attachment sites. Ideally, the biomechanical properties of the entire graft construct would approach those of the native ligament and facilitate biologic incorporation of the graft. Fixation should be done at the normal anatomic attachment site of the native ligament (aperture fixation) and, over time, allow the biologic return of the histologic transition zone from ligament to fibrocartilage, to calcified fibrocartilage, to bone. The purpose of this article is to review current fixation devices and techniques in cruciate ligament surgery.

The influence of screw geometry on hamstring tendon interference fit fixation.

We used a standardized model of calf tibial bone to investigate the influence of screw diameter and length on interference fit fixation of a three-stranded semitendinosus tendon graft for anterior cruciate ligament reconstruction. Biodegradable poly-(L-lactide) interference screws with a diameter of 7, 8, and 9 mm and a length of 23 and 28 mm were used. We examined results in three groups of 10 specimens each: group 1, screw diameter equaled graft diameter and screw length was 23 mm; group 2, screw diameter equaled graft diameter plus 1 mm and screw length was 23 mm; group 3, screw diameter equaled graft diameter and screw length was 28 mm. The mean pull-out forces in groups 1, 2, and 3 were 367.2+/-78 N, 479.1+/-111.1 N, and 537.4+/-139.1 N, respectively. The force data from groups 2 and 3 were significantly higher than those from group 1. These results indicate that screw geometry has a significant influence on hamstring tendon interference fit fixation. Increasing screw length improves fixation strength more than oversizing the screw diameter. This is important, especially for increasing tibial fixation strength because the tibial graft fixation site has been considered to be the weak link of such a reconstruction.

Biodegradable interference screw fixation exhibits pull-out force and stiffness similar to titanium screws.

Recently, increased interest in biodegradable interference screws for bone-tendon-bone graft fixation has led to numerous screws becoming available. The implants are made from different polymers and have different designs, which might influence their mechanical properties. Several studies have reported a wide range of mechanical results for these screws using different biomechanical models. The aim of the present study is to compare reliable biomechanical data for six different biodegradable interference screws, consisting of five different polymers, with a conventional titanium screw in a standardized model. Seventy proximal calf tibias were used to determine maximal pull-out force, stiffness of fixation, and insertion torque for interference screw fixation of bone-tendon-bone grafts. Additionally, maximal torque at failure was determined. Data were analyzed with respect to aspects of screw design, such as drive and thread shape. Five of the six biodegradable screws provided initial pull-out force and stiffness of fixation comparable with that of a conventional titanium screw. Torque at failure can be greatly increased by adapting the drive design to the mechanical properties of the polymeric raw material. A correlation between pull-out force and thread height indicates that fixation rigidity depends on screw design, even in a biodegradable implant.

Biomechanical properties and vascularity of an anterior cruciate ligament graft can be predicted by contrast-enhanced magnetic resonance imaging. A two-year study in sheep.

Magnetic resonance imaging has been used to determine graft integrity and study the remodeling process of anterior cruciate ligament grafts morphologically in humans. The goal of the present study was to compare graft signal intensity and morphologic characteristics on magnetic resonance imaging with biomechanical and histologic parameters in a long-term animal model. Thirty sheep underwent anterior cruciate ligament reconstruction with an autologous Achilles tendon split graft and were sacrificed after 6, 12, 24, 52, or 104 weeks. Before sacrifice, all animals underwent plain and contrast-enhanced (gadolinium-diethylenetriamine pentacetic acid) magnetic resonance imaging (1.5 T, proton density weighted, 2-mm sections) of their operated knees. The signal/noise quotient was calculated and data were correlated to the maximum load to failure, tensile strength, and stiffness of the grafts. The vascularity of the grafts was determined immunohistochemically by staining for endothelial cells (factor VIII). We found that high signal intensity on magnetic resonance imaging reflects a decrease of mechanical properties of the graft during early remodeling. Correlation analyses revealed significant negative linear correlations between the signal/noise quotient and the load to failure, stiffness, and tensile strength. In general, correlations for contrast-enhanced measurements of signal intensity were stronger than those for plain magnetic resonance imaging. Immunohistochemistry confirmed that contrast medium enhancement reflects the vascular status of the graft tissue during remodeling. We conclude that quantitatively determined magnetic resonance imaging signal intensity may be a useful tool for following the graft remodeling process in a noninvasive manner.

[Value of various MR sequences using 1.5 and 3.0 Tesla in analyzing cartilaginous defects of the patella in an animal model]. / Wertigkeit verschiedener MR-Sequenzen bei einer Feldstärke von 1.5- und 3.0 Tesla für die Analyse von Knorpeldefekten der Patella im Tiermodell.

PURPOSE: Comparison of MRI and macropathologic evaluation using various sequences and field strengths in the detection, localization and measurement of cartilage defects in an animal model. MATERIALS AND METHODS: After open creation of retropatellar cartilage defects of various widths, depths and locations in 8 cadaveric sheep knee joints, the knees were examined using a fat-suppressed (FS), proton density-weighted (PD) fast spin echo (FSE), and 2D and 3D gradient echo (GE) sequences on 1.5 T and 3.0 T MR scanners. The images were analyzed by two independent radiologists in a blinded manner, by dividing the patella into 15 virtual segments. The results were correlated with the macropathologic findings with regards to location, width, and depth of the defects. RESULTS: The highest sensitivity (67.1 %), diagnostic accuracy (85.4 %), positive (87.3 %), and negative (84.7 %) predictive values in detecting defects were obtained using the 3.0 T FS-3D-GE sequence. The highest specificity (95.6 %) yielded the 3.0 T FS-2D-GE sequence, with the other sequences inferior by no more than 2.6 %. In general, FS-3D-GE sequences were superior to FS-2D-GE (3.0 T: p < 0.05; 1.5 T: p < 0.05) and especially to FS-PD-FSE sequences (3.0 T: p < 0.01; 1.5 T: p < 0.05). In determining the defects' widths, the 3.0 T FS-3D-GE sequence was superior to all other sequences (correct measurements: 50.0 %), with only slight superiority to the 1.5 T FS-3D-GE sequence (46.9 %, p > 0.05) but clear superiority to the other sequences (28.1 - 40.6 %, vs. 1.5 T FS-PD-FSE: p < 0.05, vs. other sequences: p > 0.05). To determine the defects' depths, the 1.5 T FS-3D-GE sequence was most reliable (correct measurements: 53.1 %), followed by the 3.0 T FS-3D-GE sequence (50.0 %, significance of difference: p > 0.05). CONCLUSION: In detecting cartilage defects, the field strength of 3.0 Tesla was only superior to 1.5 T MRI using fat-saturated 3D- or 2D-GE-sequences but not in fat-saturated proton density-weighted SE-sequences. In determination of depth and length of the defects, the higher field strength was not advantageous.

[Computed tomography of the patellofemoral alignment after arthroscopic reconstruction following patella dislocation]. / Postoperative Bestimmung des patellofemoralen Alignements nach Patellaluxation--eine computertomographische Analyse.

PURPOSE: To evaluate the diagnostic impact of different CT-based measurements to analyze the patellofemoral alignment after arthroscopic reconstruction in patients with patella dislocation. MATERIALS AND METHODS: In 18 patients with dislocation of the patella, CT of the patellofemoral joint was performed after arthroscopic reconstruction. Various methods recommended in the literature were used to analyze the structure and the alignment of the patellofemoral joint with a relaxed quadriceps muscle. Axial CT scans were taken in four different knee flexion angles (15 degrees, 30 degrees, 45 degrees, 60 degrees ). RESULTS: After arthroscopic stabilization in patients with patella dislocation, only the lateral patellofemoral angle (15 degrees and 30 degrees knee flexion) and the congruence angle (15 degrees knee flexion) showed significant differences between the CT-measurements in the normal and the operated group. The differences of the remaining mean values were not significant due to a high standard deviation. With increasing flexion of the knee, the differences between the normal and the dislocation group almost disappeared. Only the lateral patellofemoral angle, the patella tilt and the lateral patella shift revealed differences between the normal and the group with recurrent dislocation in every degree of knee flexion. With increasing knee flexion above 30 degrees and especially at 60 degrees, the majority of the measured values returned to the normal range. CONCLUSIONS: For CT-measurements of the patellofemoral joint after arthroscopic stabilization, the patellofemoral angle and the congruence angle seemed to be most useful. The measurements of the patellofemoral joint should be taken in various degrees of knee flexion.

Foreign-body reaction and the course of osteolysis after polyglycolide implants for fracture fixation: experimental study in sheep.

Foreign-body reaction to polyglycolide (PGA) implants has been described in man. Many animal experiments have verified the mechanical properties of fixation devices made from PGA, but a significant foreign-body reaction has not been described. We studied the effect of PGA rods in 12 sheep with standardised osteochondral fractures of the medial femoral condyle fixed with uncoloured, self-reinforced PGA rods (Biofix). Radiographs were taken at intervals ranging from two weeks to two years, and the sheep were killed at intervals ranging from six to 24 months. All knees were examined histologically. Eleven of the 12 fractures healed radiologically and histologically. Moderate to severe osteolysis was seen at four to six weeks with maximum changes at 12 weeks in ten animals. Six knees showed fistula-like connections between the implant site and the joint space. Three developed synovitis, one with inflammatory changes involving the whole cartilage and one with destruction of the medial condyle. Although in our study osteochondral fractures fixed with PGA rods healed reliably, there were frequent, significant foreign-body reactions. Caution is needed when considering the use of PGA fixation devices in vulnerable regions such as the knee.