Introduction

Cell-based therapies become more and more prominent for the treatment of intervertebral disc (IVD) injuries. Different strategies are under current development and address the restoration of either annulus fibrosus (AF) or nucleus pulposus (NP). Application of such Advanced Therapy Medicinal Products (ATMPs) is strictly regulated. One requirement is to show the identity of the cells, to make sure the cells are indeed AF or NP cells and retained their IVD cell character during manufacturing process before injection to the site of injury. Therefore, we recently identified novel marker genes that discriminate AF and NP cells on tissue level. However, expression of these AF and NP tissue markers has not been investigated in cultured cells, yet. The aim of this study was to proof the tissue marker”s specificity to discriminate cultured AF and NP cells. Furthermore, we evaluated the tissue markers robustness to different cell culture conditions.

Introduction. The increased prevalence of osteoporosis in the patient population undergoing reverse shoulder arthroplasty (RSA) results in significantly increased complication rates. Mainly demographic and clinical predictors are currently taken into the preoperative assessment for risk stratification without quantification of preoperative computed tomography (CT) data (e.g. bone density). It was hypothesized that preoperative CT bone density measures would provide objective quantification with subsequent classification of the patients’ humeral bone quality. Methods. Thirteen bone density parameters from 345 preoperative CT scans of a clinical RSA cohort represented the data set in this study. The data set was divided into testing (30%) and training data (70%), latter included an 8-fold cross validation. Variable selection was performed by choosing the variables with the highest descriptive value for each correlation clustered variables. Machine learning models were used to improve the clustering (Hierarchical Ward) and classification (Support Vector Machine (SVM)) of bone densities at risk for complications and were compared to a conventional statistical model (Logistic Regression (LR)). Results. Clustering partitioned this cohort (training data set) into a high bone density subgroup consisting of 96 patients and a low bone density subgroup consisting of 146 patients. The optimal number of clusters (n = 2) was determined based on optimization metrics. Discrimination of the cross validated classification model showed comparable performance for the training (accuracy=91.2%; AUC=0.967) and testing data (accuracy=90.5 %; AUC=0.958) while outperforming the conventional statistical model (Logistic Regression (LR)). Local interpretable model-agnostic explanations (LIME) were created for each patient to explain how the predicted output was achieved. Conclusion. The trained and tested model provides preoperative information for surgeons treating patients with potentially poor bone quality. The use of machine learning and patient-specific calibration showed that multiple 3D bone density scores improved accuracy for objective preoperative bone quality assessment

Quantitative ultrasound (QUS) is a promising tool to estimate bone structure characteristics and predict fragile fracture. The aim of this pilot cross-sectional study was to evaluate the performance of a multi-channel residual network (MResNet) based on ultrasonic radiofrequency (RF) signal to discriminate fragile fractures retrospectively in postmenopausal women. Methods. RF signal and speed of sound (SOS) were obtained using an axial transmission QUS at one‐third distal radius for 246 postmenopausal women. Based on the involved RF signal, we conducted a MResNet, which combines multi-channel training with original ResNet, to classify the high risk of fragility fractures patients from all subjects. The bone mineral density (BMD) at lumber, hip and femoral neck acquired with DXA was recorded on the same day. The fracture history of all subjects in adulthood were collected. To assess the ability of the different methods in the discrimination of fragile fracture, the odds ratios (OR) calculated using binomial logistic regression analysis and the area under the receiver operator characteristic curves (AUC) were analyzed. Results. Among the 246 postmenopausal women, 170 belonged to the non-fracture group, 50 to the vertebral group, and 26 to the non-vertebral fracture group. MResNet was discriminant for all fragile fractures (OR = 2.64; AUC = 0.74), for Vertebral fracture (OR = 3.02; AUC = 0.77), for non-vertebral fracture (OR = 2.01; AUC = 0.69). MResNet showed comparable performance to that of BMD of hip and lumbar with all types of fractures, and significantly better performance than SOS all types of fractures. Conclusions. the MResNet model based on the ultrasonic RF signal can significantly improve the ability of QUS device to recognize previous fragile fractures. Moreover, the performance of the proposed model modified by age, weight, and height is further optimized. These results open perspectives to evaluate the risk of fragile fracture applying a deep learning model to analyze ultrasonic RF signal

The postoperative course of median nerve decompression in the carpal tunnel syndrome may sometimes be complicated by postoperative pain, paresthesias, and other unpleasant symptoms, or be characterized by a slow recovery of nerve function due to prolonged preoperative injury causing extensive nerve damage. The aim of this study is to explore any possible effects of alpha lipoic acid (ALA) in the postoperative period after surgical decompression of the median nerve at the wrist. Patients were enrolled with proven carpal tunnel syndrome and randomly assigned into one of two groups: Group A: surgical decompression of the median nerve followed by ALA for 40 days. Group P: surgical decompression followed by placebo. The primary endpoint of the study was nerve conduction velocity at 3 months post surgery, Other endpoints were static 2 point discrimination, the Boston score for hand function, pillar pain and use of pain killers beyond the second postoperative day. ALA did not show to significantly improve nerve conduction velocity or Boston score. However, a statistically significant reduction in the postoperative incidence of pillar pain was noted in Group A. In addition, static 2 point discrimination showed to be significantly improved by ALA. Administration of ALA following decompression of the median nerve for carpal tunnel release is effective on nerve recovery, although this is not detectable through nerve conduction studies but in terms of accelerated and improved static two-point discrimination. The use of ALA as a supplementation for nerve recovery after surgical decompression may be extended to all types of compression syndromes or conditions where a nerve is freed from a mechanical insult. Furthermore, ALA limits post-decompression pain, including late pericicatricial pain at the base of the palm, the so called pillar pain, which seems to be associated with a reversible damage to the superfical sensitive small nerve fibers. In conclusion postoperative administration of ALA for 40 days post-median nerve decompression was positively associated with nerve recovery, induced a lower incidence of postoperative pillar pain and was associated with a more rapid improvement of static two-point discrimination. This treatment is well tolerated and associated with high levels of satisfaction and compliance, supporting its value as a standard postoperative supplementation after carpal tunnel decompression

Objectives. The objective of this study was to develop a test for the rapid (within 25 minutes) intraoperative detection of bacteria from synovial fluid to diagnose periprosthetic joint infection (PJI). Methods. The 16s rDNA test combines a polymerase chain reaction (PCR) for amplification of 16s rDNA with a lateral flow immunoassay in one fully automated system. The synovial fluid of 77 patients undergoing joint aspiration or primary or revision total hip or knee surgery was prospectively collected. The cohort was divided into a proof-of-principle cohort (n = 17) and a validation cohort (n = 60). Using the proof-of-principle cohort, an optimal cut-off for the discrimination between PJI and non-PJI samples was determined. PJI was defined as detection of the same bacterial species in a minimum of two microbiological samples, positive histology, and presence of a sinus tract or intra-articular pus. Results. The 16s rDNA test proved to be very robust and was able to provide a result in 97% of all samples within 25 minutes. The 16s rDNA test was able to diagnose PJI with a sensitivity of 87.5% and 82%, and a specificity of 100% and 89%, in the proof-of-principle and validation cohorts, respectively. The microbiological culture of synovial fluid achieved a sensitivity of 80% and a specificity of 93% in the validation cohort. Conclusion. The 16s rDNA test offers reliable intraoperative detection of all bacterial species within 25 minutes with a sensitivity and specificity comparable with those of conventional microbiological culture of synovial fluid for the detection of PJI. The 16s rDNA test performance is independent of possible blood contamination, culture time and bacterial species. Cite this article: V. Janz, J. Schoon, C. Morgenstern, B. Preininger, S. Reinke, G. Duda, A. Breitbach, C. F. Perka, S. Geissler. Rapid detection of periprosthetic joint infection using a combination of 16s rDNA polymerase chain reaction and lateral flow immunoassay: A Pilot Study. Bone Joint Res 2018;7:12–19. DOI: 10.1302/2046-3758.71.BJR-2017-0103.R2

Introduction. Human bone marrow-derived mesenchymal stem cells (hBMSCs) can adopt either an immune suppressive or stimulative phenotype in response to cytokines and pathogen-associated molecular patterns (PAMPs). It is known that the glycoprotein CD24 allows for the discrimination between PAMPs and DAMPs in dendritic cells. We were able to show previously that CD24 is expressed by hBMSCs and found that its overexpression leads to the downregulation of NF-kB-regulated genes, as well as induction of the anti-inflammatory TGF beta. In the present study the influence of various PAMPs and cytokines on the expression of CD24 in hBMSCs was analysed. Furthermore, it was tested whether in vivo-CD24-positive (CD24+) and in vivo-CD24-negative (CD24-) hBMSCs differ in regard to classical hBMSC or immune-associated surface antigens. Methods. hBMSCs were enriched by density gradient centrifugation, cultured in vitro until passage 3 and subsequently stimulated with PAMPs or cytokines (IFN gamma, TGF beta) before analysing the expression of CD24 via qRT-PCR. Cells expressing CD24 in vivo (CD24+ hBMSCs) were enriched from bone marrow aspirates after density gradient centrifugation by the use of magnetic-associated cell sorting (MACS). Successful enrichment was evaluated by flow cytometric analysis. The enriched cells were subsequently cultured in comparison to the CD24-depleted cell population (CD24- hBMSCs) under identical conditions. The expression of various cell surface markers was compared between these two populations using flow cytometry. Results. All tested PAMPs, as well as IFN gamma led to the downregulation of CD24 in comparison to non-stimulated control cells. In contrast, stimulation with TGF beta resulted in an increased CD24 expression. CD24-positive hBMSCs were successfully enriched via MACS and cultured in vitro. While there was no difference between the expression of classical hBMSC surface antigens between the two cell populations, the CD24+ population had a significantly higher expression of PD-L1 than the CD24- population. Discussion. hBMSCs are capable of ameliorating autoimmune processes by inducing T-cell anergy. Polymorphisms in CD24 are associated with the development of autoimmune diseases. In this context it is worth of note that CD24+ hBMSCs show an elevated expression of PD-L1. PD-L1 is a molecule that can induce anergy in T cells by binding to PD-1 thereby dampening the immune response to self antigens. Therefore, hBMSCs with strong CD24-expression might be beneficial in treating autoimmune diseases such as rheumatoid arthritis. PAMPs and IFN-gamma lead to the downregulation of CD24, which may strip hBMSCs of their ability to induce T cell anergy and to dampen immune responses to self antigens

The evaluation of knee stability is fundamental for the clinical discrimination between healthy and pathological joints, for the design and evaluation of prostheses and for the definition of articular models. Knee stability can be quantified by measuring the relation between applied single-axis constant loads and corresponding tibio-femoral displacements (i.e., translations and rotations), namely the joint stiffness, at a given flexion angle. No many studies are available in the literature on this topic [1–3]. In particular, the translations/rotations along/about directions different from the loaded one were not deeply investigated. A fresh frozen lower-limb specimen (female, 63 years old, weight 68 Kg, height 158 cm) was considered. The forefoot and all soft tissues outside the knee were removed by a surgeon, keeping the knee joint capsule intact. A stereophotogrammetric system (Vicon Motion Systems Ltd.) was used to measure the femoro-tibial relative motion by two trackers fixed to the bones, thus introducing no soft-tissue artifact. The specimen was then mounted on a test rig capable to exert general loading conditions [4], and constant loads were applied to the tibia: ±100 N in antero-posterior (AP) and medio-lateral (ML) direction; ±10 Nm about abb-adduction (AA) and in-external (IE) rotations. Loads were applied approximately at the mid-point between the lateral and medial epicondyles, and were kept constant while the femur was flexed over a 135° range. Displacements were defined with respect to the joint natural motion (RTNM), also registered with the same rig. The relative motion of the bones was expressed by a standard joint coordinate system [5]. Considerable translations/rotations appeared also on different directions than the loaded one. At 90° of flexion, an anterior load of +100 N produced 5.5 mm of anterior translation, 10.9 mm of medial translation and 12° of external rotation of the tibia (RTNM). When not directly loaded in ML and IE directions, the tibia translated medially and rotated externally, independently from the sign of the applied load: at 90° of flexion, an AA torque of +10 Nm and −10 Nm produced respectively 5 mm and 8.9 mm of medial translation, and 5.5° and 7.5° of external rotation of the tibia (RTNM). The load/displacement relation was highly non linear also for the loading direction. At 90° of flexion, IE torques of +10 Nm and −10 Nm produced respectively 3.6° of internal and 14.2° of external rotation of the tibia (RTNM). The knee joint structures make the relation between applied loads and bone displacements highly non linear. As a result, a load acting on one direction produces a complex three-dimensional joint motion. Future work will extend the presented analysis on several specimens, also increasing the magnitude and the number of loading conditions

Objectives

Given the function of adiponectin (ADIPOQ) on the inflammatory condition of obesity and osteoarthritis (OA), we hypothesized that the ADIPOQ gene might be a candidate gene for a marker of susceptibility to OA.

Impaction allograft is an established method of securing initial stability of an implant in arthroplasty. Subsequent bone integration can be prolonged, and the volume of allograft may not be maintained. Intermittent administration of parathyroid hormone has an anabolic effect on bone and may therefore improve integration of an implant.

Using a canine implant model we tested the hypothesis that administration of parathyroid hormone may improve osseointegration of implants surrounded by bone graft. In 20 dogs a cylindrical porous-coated titanium alloy implant was inserted into normal cancellous bone in the proximal humerus and surrounded by a circumferential gap of 2.5 mm. Morsellised allograft was impacted around the implant. Half of the animals were given daily injections of human parathyroid hormone (1–34) 5 μg/kg for four weeks and half received control injections. The two groups were compared by mechanical testing and histomorphometry. We observed a significant increase in new bone formation within the bone graft in the parathyroid hormone group. There were no significant differences in the volume of allograft, bone-implant contact or in the mechanical parameters.

These findings suggest that parathyroid hormone improves new bone formation in impacted morsellised allograft around an implant and retains the graft volume without significant resorption. Fixation of the implant was neither improved nor compromised at the final follow-up of four weeks.

The understanding of rotational alignment of the distal femur is essential in total knee replacement to ensure that there is correct placement of the femoral component. Many reference axes have been described, but there is still disagreement about their value and mutual angular relationship. Our aim was to validate a geometrically-defined reference axis against which the surface-derived axes could be compared in the axial plane. A total of 12 cadaver specimens underwent CT after rigid fixation of optical tracking devices to the femur and the tibia. Three-dimensional reconstructions were made to determine the anatomical surface points and geometrical references. The spatial relationships between the femur and tibia in full extension and in 90° of flexion were examined by an optical infrared tracking system.

After co-ordinate transformation of the described anatomical points and geometrical references, the projection of the relevant axes in the axial plane of the femur were mathematically achieved. Inter- and intra-observer variability in the three-dimensional CT reconstructions revealed angular errors ranging from 0.16° to 1.15° for all axes except for the trochlear axis which had an interobserver error of 2°. With the knees in full extension, the femoral transverse axis, connecting the centres of the best matching spheres of the femoral condyles, almost coincided with the tibial transverse axis (mean difference −0.8°, sd 2.05). At 90° of flexion, this femoral transverse axis was orthogonal to the tibial mechanical axis (mean difference −0.77°, sd 4.08). Of all the surface-derived axes, the surgical transepicondylar axis had the closest relationship to the femoral transverse axis after projection on to the axial plane of the femur (mean difference 0.21°, sd 1.77). The posterior condylar line was the most consistent axis (range −2.96° to −0.28°, sd 0.77) and the trochlear anteroposterior axis the least consistent axis (range −10.62° to +11.67°, sd 6.12). The orientation of both the posterior condylar line and the trochlear anteroposterior axis (p = 0.001) showed a trend towards internal rotation with valgus coronal alignment.

To clarify the pathomechanisms of discogenic low back pain, the sympathetic afferent discharge originating from the L5-L6 disc via the L2 root were investigated neurophysiologically in 31 Lewis rats. Sympathetic afferent units were recorded from the L2 root connected to the lumbar sympathetic trunk by rami communicantes. The L5-L6 discs were mechanically probed, stimulated electrically to evoke action potentials and, finally, treated with chemicals to produce an inflammatory reaction. We could not obtain a response from any units in the L5-L6 discs using mechanical stimulation, but with electrical stimulation we identified 42 units consisting mostly of A-delta fibres. In some experiments a response to mechanical probing of the L5-L6 disc was recognised after producing an inflammatory reaction. This study suggests that mechanical stimulation of the lumbar discs may not always produce pain, whereas inflammatory changes may cause the disc to become sensitive to mechanical stimuli, resulting in nociceptive information being transmitted as discogenic low back pain to the spinal cord through the lumbar sympathetic trunk. This may partly explain the variation in human symptoms of degenerate discs.

We investigated several factors which affect the stability of cortical screws in osteoporotic bone using 18 femora from cadavers of women aged between 45 and 96 years (mean 76). We performed bone densitometry to measure the bone mineral density of the cortical and cancellous bone of the shaft and head of the femur, respectively. The thickness and overall bone mass of the cortical layer of the shaft of the femur were measured using a microCT scanner. The force required to pull-out a 3.5 mm titanium cortical bone screw was determined after standardised insertion into specimens of the cortex of the femoral shaft.

A significant correlation was found between the pull-out strength and the overall bone mass of the cortical layer (r² = 0.867, p < 0.01) and also between its thickness (r² = 0.826, p < 0.01) and bone mineral density (r² = 0.861, p < 0.01). There was no statistically significant correlation between the age of the donor and the pull-out force (p = 0.246), the cortical thickness (p = 0.199), the bone mineral density (p = 0.697) or the level of osteoporosis (p = 0.378).

We conclude that the overall bone mass, the thickness and the bone mineral density of the cortical layer, are the main factors which affect the stability of a screw in human female osteoporotic cortical bone.

The effect of zoledronic acid on bone ingrowth was examined in an animal model in which porous tantalum implants were placed bilaterally within the ulnae of seven dogs. Zoledronic acid in saline was administered via a single post-operative intravenous injection at a dose of 0.1 mg/kg. The ulnae were harvested six weeks after surgery. Undecalcified transverse histological sections of the implant-bone interfaces were imaged with backscattered scanning electron microscopy and the percentage of available pore space that was filled with new bone was calculated. The mean extent of bone ingrowth was 6.6% for the control implants and 12.2% for the zoledronic acid-treated implants, an absolute difference of 5.6% (95% confidence interval, 1.2 to 10.1) and a relative difference of 85% which was statistically significant. Individual islands of new bone formation within the implant pores were similar in number in both groups but were 69% larger in the zoledronic acid-treated group. The bisphosphonate zoledronic acid should be further investigated for use in accelerating or enhancing the biological fixation of implants to bone.