Distances and angles in standing long-leg radiographs: comparing conventional radiography, digital radiography, and EOS.

OBJECTIVE: Distances and angles measured from long-leg radiographs (LLR) are important for surgical decision-making. However, projectional radiography suffers from distortion, potentially generating differences between measurement and true anatomical dimension. These phenomena are not uniform between conventional radiography (CR) digital radiography (DR) and fan-beam technology (EOS). We aimed to identify differences between these modalities in an experimental setup. MATERIALS AND METHODS: A hemiskeleton was stabilized using an external fixator in neutral, valgus and varus knee alignment. Ten images were acquired for each alignment and each modality: one CR setup, two different DR systems, and an EOS. A total of 1680 measurements were acquired and analyzed. RESULTS: We observed great differences for dimensions and angles between the 4 modalities. Femoral head diameter measurements varied in the range of > 5 mm depending on the modality, with EOS being the closest to the true anatomical dimension. With functional leg length, a difference of 8.7% was observed between CR and EOS and with the EOS system being precise in the vertical dimension on physical-technical grounds, this demonstrates significant projectional magnification with CR-LLR. The horizontal distance between the medial malleoli varied by 20 mm between CR and DR, equating to 21% of the mean. CONCLUSIONS: Projectional distortion resulting in variations approaching 21% of the mean indicate, that our confidence on measurements from standing LLR may not be justified. It appears likely that among the tested equipment, EOS-generated images are closest to the true anatomical situation most of the time.

One-year follow-up-case report of secondary tension pneumothorax in a COVID-19 pneumonia patient.

PURPOSE: The Coronavirus Disease 2019 (COVID-19) may result not only in acute symptoms such as severe pneumonia, but also in persisting symptoms after months. Here we present a 1 year follow-up of a patient with a secondary tension pneumothorax due to COVID-19 pneumonia. CASE PRESENTATION: In May 2020, a 47-year-old male was admitted to the emergency department with fever, dry cough, and sore throat as well as acute chest pain and shortness of breath. Sputum testing (polymerase chain reaction, PCR) and computed tomography (CT) confirmed infection with the severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2). Eleven days after discharge, the patient returned to the emergency department with pronounced dyspnoea after coughing. CT showed a right-sided tension pneumothorax, which was relieved by a chest drain (Buelau) via mini open thoracotomy. For a period of 3 months following resolution of the pneumothorax the patient complained of fatigue with mild joint pain and dyspnoea. After 1 year, the patient did not suffer from any persisting symptoms. The pulmonary function and blood parameters were normal, with the exception of slightly increased levels of D-Dimer. The CT scan revealed only discrete ground glass opacities (GGO) and subpleural linear opacities. CONCLUSION: Tension pneumothorax is a rare, severe complication of a SARS-CoV-2 infection but may resolve after treatment without negative long-term sequelae. LEVEL OF EVIDENCE: V.

Atrophy patterns in isolated subscapularis lesions.

BACKGROUND: While supraspinatus atrophy can be described according to the system of Zanetti or Thomazeau there is still a lack of characterization of isolated subscapularis muscle atrophy. The aim of this study was to describe patterns of muscle atrophy following repair of isolated subscapularis (SSC) tendon. METHODS: Forty-nine control shoulder MRI scans, without rotator cuff pathology, atrophy or fatty infiltration, were prospectively evaluated and subscapularis diameters as well as cross sectional areas (complete and upper half) were assessed in a standardized oblique sagittal plane. Calculation of the ratio between the upper half of the cross sectional area (CSA) and the total CSA was performed. Eleven MRI scans of patients with subscapularis atrophy following isolated subscapularis tendon tears were analysed and cross sectional area ratio (upper half /total) determined. To guarantee reliable measurement of the CSA and its ratio, bony landmarks were also defined. All parameters were statistically compared for inter-rater reliability, reproducibility and capacity to quantify subscapularis atrophy. RESULTS: The mean age in the control group was 49.7 years (± 15.0). The mean cross sectional area (CSA) was 2367.0 mm2 (± 741.4) for the complete subscapularis muscle and 1048.2 mm2 (± 313.3) for the upper half, giving a mean ratio of 0.446 (± 0.046). In the subscapularis repair group the mean age was 56.7 years (± 9.3). With a mean cross sectional area of 1554.7 mm2 (± 419.9) for the complete and of 422.9 mm2 (± 173.6) for the upper half of the subscapularis muscle, giving a mean CSA ratio of 0.269 (± 0.065) which was seen to be significantly lower than that of the control group (p < 0.05). CONCLUSION: Analysis of typical atrophy patterns of the subscapularis muscle demonstrates that the CSA ratio represents a reliable and reproducible assessment tool in quantifying subscapularis atrophy. We propose the classification of subscapularis atrophy as Stage I (mild atrophy) in case of reduction of the cross sectional area ratio < 0.4, Stage II (moderate atrophy) in case of < 0.35 and Stage III (severe atrophy) if < 0.3.

In vitro evaluation of antibacterial efficacy of vancomycin-loaded suture tapes and cerclage wires.

Usage of implants containing antibiotic agents has been a common strategy to prevent implant related infections in orthopedic surgery. Unfortunately, most implants with microbial repellent properties are characterized by accessibility limitations during daily clinical practice. Aim of this in vitro study was to investigate whether suture tapes and cerclage wires, which were treated with vancomycin, show a sustainable antibacterial activity. For this purpose, we used 24 stainless steel wire cerclages and 24 ultra-high molecular weight polyethylene and polyester suture tape test bodies. The test bodies were incubated for 30 min. in 100 mg/ml vancomycin solution or equivalent volumes of 0.9% NaCl. After measuring the initial solution uptake of the test bodies, antibacterial efficacy via agar diffusion test with Staphylococcus aureus and vancomycin elution tests were performed 1, 2, 3, and 6 days after incubation. Vancomycin-loaded tapes as well as vancomycin-loaded cerclage wires demonstrated increased bacterial growth inhibition when compared to NaCl-treated controls. Vancomycin-loaded tapes showed an additional twofold and eightfold increase of bacterial growth inhibition compared to vancomycin-loaded wires at day 1 and 2, respectively. Elution tests at day 1 revealed high levels of vancomycin concentration in vancomycin loaded tapes and wires. Additionally, the concentration in vancomycin loaded tapes was 14-fold higher when compared to vancomycin loaded wires. Incubating suture tapes and cerclage wires in vancomycin solution showed a good short-term antibacterial activity compared to controls. Considering the ease of vancomycin application on suture tapes or wires, our method could represent an attractive therapeutic strategy in biofilm prevention in orthopedic surgery.

Effect of Mobilization on the Day of Surgery After Total Hip Arthroplasty in Elderly, Obese, and Severely Diseased Patients.

BACKGROUND: Mobilization on the day of surgery after total hip arthroplasty (THA) is widely used. However, elderly, obese and severely diseased patients are often excluded from early mobilization. Therefore, it was our aim to investigate the effect of mobilization on the day of surgery with focus on these patients. METHODS: 167 patients underwent THA via direct anterior approach. Exclusion criterion was the use of wound drainage. The patients were randomly allocated to two groups. Day 0 group was mobilized 4 hours after surgery, day 1 group the day after surgery. Primary outcome was the time to readiness for discharge (TRD). Secondary outcome was the occurrence of adverse events (vertigo, nausea, vomiting, severe pain) on the day of surgery. Group comparisons were calculated with respect to elderly (age ≥75 years), obese (BMI ≥30 kg/m2) and severely diseased patients (ASA≥3). RESULTS: TRD was shorter in day 0 group (3.25 vs 3.99 days, P < .01). The rate of adverse events on the day of surgery was similar in both groups (0.28 vs 0.25, P = .73). TRD differences were higher within all subgroups (3.85vs4.81; 3.25vs4.39; 4.08vs5.11days) while the rate of immediate adverse events was reduced (0.15vs0.24; 0.25vs0.3; 0.25vs0.33). Within 90 days 3 patients of group 0 underwent revision surgery, none of group 1 (P = .12). CONCLUSION: Mobilization on the day of surgery reduces the TRD without increasing the rate of immediate adverse events, regardless of age, BMI and ASA score. Future studies are needed to investigate if early mobility increases the 90-days complication rate.

Accurate implant fit and leg alignment after cruciate-retaining patient-specific total knee arthroplasty.

BACKGROUND: For improved outcomes in total knee arthroplasty (TKA) correct implant fitting and positioning are crucial. In order to facilitate a best possible implant fitting and positioning patient-specific systems have been developed. However, whether or not these systems allow for better implant fitting and positioning has yet to be elucidated. For this reason, the aim was to analyse the novel patient-specific cruciate retaining knee replacement system iTotal™ CR G2 that utilizes custom-made implants and instruments for its ability to facilitate accurate implant fitting and positioning including correction of the hip-knee-ankle angle (HKA). METHODS: We assessed radiographic results of 106 patients who were treated with the second generation of a patient-specific cruciate retaining knee arthroplasty using iTotal™ CR G2 (ConforMIS Inc.) for tricompartmental knee osteoarthritis (OA) using custom-made implants and instruments. The implant fit and positioning as well as the correction of the mechanical axis (hip-knee-ankle angle, HKA) and restoration of the joint line were determined using pre- and postoperative radiographic analyses. RESULTS: On average, HKA was corrected from 174.4° ± 4.6° preoperatively to 178.8° ± 2.2° postoperatively and the coronal femoro-tibial angle was adjusted on average 4.4°. The measured preoperative tibial slope was 5.3° ± 2.2° (mean +/- SD) and the average postoperative tibial slope was 4.7° ± 1.1° on lateral views. The joint line was well preserved with an average modified Insall-Salvati index of 1.66 ± 0.16 pre- and 1.67 ± 0.16 postoperatively. The overall accuracy of fit of implant components was decent with a measured medial overhang of more than 1 mm (1.33 mm ± 0.32 mm) in 4 cases only. Further, a lateral overhang of more than 1 mm (1.8 mm ± 0.63) (measured in the anterior-posterior radiographs) was observed in 11 cases, with none of the 106 patients showing femoral notching. CONCLUSION: The patient-specific iTotal™ CR G2 total knee replacement system facilitated a proper fitting and positioning of the implant components. Moreover, a good restoration of the leg axis towards neutral alignment was achieved as planned. Nonetheless, further clinical follow-up studies are necessary to validate our findings and to determine the long-term impact of using this patient- specific system.

The human arthritic hip joint is a source of mesenchymal stromal cells (MSCs) with extensive multipotent differentiation potential.

BACKGROUND: While multiple in vitro studies examined mesenchymal stromal cells (MSCs) derived from bone marrow or hyaline cartilage, there is little to no data about the presence of MSCs in the joint capsule or the ligamentum capitis femoris (LCF) of the hip joint. Therefore, this in vitro study examined the presence and differentiation potential of MSCs isolated from the bone marrow, arthritic hyaline cartilage, the LCF and full-thickness samples of the anterior joint capsule of the hip joint. METHODS: MSCs were isolated and multiplied in adherent monolayer cell cultures. Osteogenesis and adipogenesis were induced in monolayer cell cultures for 21 days using a differentiation medium containing specific growth factors, while chondrogenesis in the presence of TGF-ß1 was performed using pellet-culture for 27 days. Control cultures were maintained for comparison over the same duration of time. The differentiation process was analyzed using histological and immunohistochemical stainings as well as semiquantitative RT-PCR for measuring the mean expression levels of tissue-specific genes. RESULTS: This in vitro research showed that the isolated cells from all four donor tissues grew plastic-adherent and showed similar adipogenic and osteogenic differentiation capacity as proven by the histological detection of lipid droplets or deposits of extracellular calcium and collagen type I. After 27 days of chondrogenesis proteoglycans accumulated in the differentiated MSC-pellets from all donor tissues. Immunohistochemical staining revealed vast amounts of collagen type II in all differentiated MSC-pellets, except for those from the LCF. Interestingly, all differentiated MSCs still showed a clear increase in mean expression of adipogenic, osteogenic and chondrogenic marker genes. In addition, the examination of an exemplary selected donor sample revealed that cells from all four donor tissues were clearly positive for the surface markers CD44, CD73, CD90 and CD105 by flow cytometric analysis. CONCLUSIONS: This study proved the presence of MSC-like cells in all four examined donor tissues of the hip joint. No significant differences were observed during osteogenic or adipogenic differentiation depending on the source of MSCs used. Further research is necessary to fully determine the tripotent differentiation potential of cells isolated from the LCF and capsule tissue of the hip joint.

Revision knee arthroplasty with rotating hinge systems in patients with gross ligament instability.

PURPOSE: The clinical and radiographic outcomes after revision total knee arthroplasty (TKA) for instability with two rotating hinge knee prostheses were compared. METHODS: Fifty-one patients revised for TKA instability were prospectively randomized to either the Link Endo-Model (N = 26) or the EnduRo (N = 25). Clinical and radiographic outcome scores were compared pre-operatively and at 12 months' follow-up. Failure mechanisms were recorded. RESULTS: Age, BMI, operation, and tourniquet-time did not differ significantly between groups. Radiographic evaluation demonstrated correct implant alignment. The Endo-Model was implanted with a higher slope (p = 0.0001) and the mechanical lower extremity axis was straighter (p = 0.0323). Except for the patient function Knee Society Score and the Physical Health Component Summary Score in the EnduRo group, all clinical scores (range of motion/knee function Knee Society Score/Oxford Knee Score/Visual Analog Scale/Mental Health Component Summary Score) improved significantly for both prosthesis designs during the follow-up period. The Visual Analog Scale and Mental Health Component Summary score were significantly better (p = 0.045 and p = 0.0148) in the Endo-Model group at the 12 months' follow-up. In the EnduRo group 2 patients (8%) and in the Endo-Model group 1 patient (3.8%) had to be revised for infection. CONCLUSION: Both prosthetic designs provide significant improvement in pain and function scores after TKA revision for gross instability. We found slight advantages in favor of the Endo-Model; however, no design yielded superior results throughout the study.

Case report - calcification of the medial collateral ligament of the knee with simultaneous calcifying tendinitis of the rotator cuff.

BACKGROUND: Calcification of the medial collateral ligament (MCL) of the knee is a very rare disease. We report on a case of a patient with a calcifying lesion within the MCL and simultaneous calcifying tendinitis of the rotator cuff in both shoulders. CASE PRESENTATION: Calcification of the MCL was diagnosed both via x-ray and magnetic resonance imaging (MRI) and was successfully treated surgically. Calcifying tendinitis of the rotator cuff was successfully treated applying conservative methods. CONCLUSION: This is the first case report of a patient suffering from both a calcifying lesion within the medial collateral ligament and calcifying tendinitis of the rotator cuff in both shoulders. Clinical symptoms, radio-morphological characteristics and macroscopic features were very similar and therefore it can be postulated that the underlying pathophysiology is the same in both diseases. Our experience suggests that magnetic resonance imaging and x-ray are invaluable tools for the diagnosis of this inflammatory calcifying disease of the ligament, and that surgical repair provides a good outcome if conservative treatment fails. It seems that calcification of the MCL is more likely to require surgery than calcifying tendinitis of the rotator cuff. However, the exact reason for this remains unclear to date.

[Total knee arthroplasty. Patient-specific instruments and implants]. / Totalendoprothetischer Kniegelenksersatz. Patientenspezifische Instrumente und Implantate.

This article describes the concept and surgical technique of patient-specific total knee arthroplasty. Patient-specific implants and instruments are designed and fabricated based on computed tomography (CT) data of the leg. The disposable patient-specific drill guides and cutting-jigs are manufactured taking into consideration the anatomical and biomechanical axes of the knee joint and mediating the efficient pre-navigation of the osseous saw-cuts, without the need for additional navigation or balancing aids. The surgical plan is made on the basis of the CT data. The implantation technique comprises the following steps: distal femoral resection, tibial resection, balancing and femur preparation, tibia preparation, optional patellar resurfacing, trialling of the test components, and implantation of the final components. By using this patient-specific implant system, which includes not only personalized, single-use instruments, but also individualized implants, the surgeon is able to provide endoprosthetic treatment that broadly restores the patient's own knee anatomy and knee kinematics. Preliminary studies have proven the concept and data on this technology are promising so far; however, like a new implant, they are usually limited. In particular, comparative long-term clinical data are still to come.

Mimicking breast cancer-induced bone metastasis in vivo: current transplantation models and advanced humanized strategies.

Bone metastasis is a complication that occurs in 80 % of women with advanced breast cancer. Despite the prevalence of bone metastatic disease, the avenues for its clinical management are still restricted to palliative treatment options. In fact, the underlying mechanisms of breast cancer osteotropism have not yet been fully elucidated due to a lack of suitable in vivo models that are able to recapitulate the human disease. In this work, we review the current transplantation-based models to investigate breast cancer-induced bone metastasis and delineate the strengths and limitations of the use of different grafting techniques, tissue sources, and hosts. We further show that humanized xenograft models incorporating human cells or tissue grafts at the primary tumor site or the metastatic site mimic more closely the human disease. Tissue-engineered constructs are emerging as a reproducible alternative to recapitulate functional humanized tissues in these murine models. The development of advanced humanized animal models may provide better platforms to investigate the mutual interactions between human cancer cells and their microenvironment and ultimately improve the translation of preclinical drug trials to the clinic.

Mono- versus polyaxial locking plates in distal femur fractures: a prospective randomized multicentre clinical trial.

PURPOSE: Treatment of complex fractures of the distal femur utilizing monoaxial locking plates (e.g. Less Invasive Stabilisation System, LISS®, Synthes) is considered to be superior to conventional plating systems. Due to the limitation that the thread forces the screw into pre-determined positions, modifications have been made to allow screw positioning within a range of 30° (Non Contact Bridging, NCB®-DF, Zimmer). For the first time, this multicenter prospective randomized clinical trial (RCT) investigates the outcome of LISS® vs. NCB®-DF treatment following complex fractures of the distal femur. METHODS: Since June 2008, 27 patients with a fracture of the distal femur (AO ASIF 33-A-C and periprosthetic fractures) were enrolled in this study by four university trauma centres in southern Germany. Clinical (e.g. range of motion, Oxford knee score, Tegner score) and radiological (e.g. axis deviation, secondary loss of realignment) follow-ups were conducted one and six weeks, as well as three, six, and 12 months after the operation. RESULTS: This study comprises data of 27 patients (8 male, 19 female; 15 NCB®-DF, 12 LISS®). Polyaxial osteosynthesis using the NCB® system tended to result in better functional knee scores and a higher range of motion. Interestingly, fracture union tended to be more rapid using the polyaxial plating system. CONCLUSIONS: We present the analysis of a multicenter prospective RCT to compare the monoaxial LISS® vs. the polyaxial NCB®-DF treatment following complex fractures of the distal femur. NCB®-DF treatment tended to result in better functional and radiological outcomes than LISS® treatment. LEVEL OF EVIDENCE: Level I.

How Framing Bias Impacts Preferences for Innovation in Bone Tissue Engineering.

It is currently unknown if surgeons and biomaterial scientists &or tissue engineers (BS&orTE) process and evaluate information in similar or different (un)biased ways. For the gold standard of surgery to move "from bench to bedside," there must naturally be synergies between these key stakeholders' perspectives. Because only a small number of biomaterials and tissue engineering innovations have been translated into the clinic today, we hypothesized that this lack of translation is rooted in the psychology of surgeons and BS&orTE. Presently, both clinicians and researchers doubt the compatibility of surgery and research in their daily routines. This has led to the use of a metaphorical expression "squaring of the circle," which implies an unsolvable challenge. As bone tissue engineering belongs to the top five research areas in tissue engineering, we choose the field of bone defect treatment options for our bias study. Our study uses an online survey instrument for data capture such as incorporating a behavioral economics cognitive framing experiment methodology. Our study sample consisted of surgeons (n = 208) and BS&orTE (n = 59). And we used a convenience sampling method, with participants (conference attendants) being approached both in person and through email between October 22, 2022, and March 13, 2023. We find no distinct positive-negative cognitive framing differences by occupation. That is, any framing bias present in this surgical decision-making setting does not appear to differ significantly between surgeon and BS&orTE specialization. When we explored within-group differences by frames, we see statistically significant (p < 0.05) results for surgeons in the positive frame ranking autologous bone graft transplantation lower than surgeons in the negative frame. Furthermore, surgeons in the positive frame rank Ilizarov bone transport method higher than surgeons in the negative frame (p < 0.05).

Acute osteomyelitis of the humerus mimicking malignancy: Streptococcus pneumoniae as exceptional pathogen in an immunocompetent adult.

BACKGROUND: Chronic osteomyelitis due to direct bone trauma or vascular insufficiency is a frequent problem in orthopaedic surgery. In contrast, acute haematogenous osteomyelitis represents a rare entity that almost exclusively affects prepubescent children or immunodeficient adults. CASE PRESENTATION: In this article, we report the case of acute pneumococcal osteomyelitis of the humerus in an immunocompetent and otherwise healthy 44-year-old male patient presenting with minor inflammation signs and misleading clinical features. CONCLUSIONS: The diagnosis had to be confirmed by open biopsy which allowed the initiation of a targeted therapy. A case of pneumococcal osteomyelitis of a long bone, lacking predisposing factors or trauma, is unique in adults and has not been reported previously.

The Concept of Scaffold-Guided Bone Regeneration for the Treatment of Long Bone Defects: Current Clinical Application and Future Perspective.

The treatment of bone defects remains a challenging clinical problem with high reintervention rates, morbidity, and resulting significant healthcare costs. Surgical techniques are constantly evolving, but outcomes can be influenced by several parameters, including the patient's age, comorbidities, systemic disorders, the anatomical location of the defect, and the surgeon's preference and experience. The most used therapeutic modalities for the regeneration of long bone defects include distraction osteogenesis (bone transport), free vascularized fibular grafts, the Masquelet technique, allograft, and (arthroplasty with) mega-prostheses. Over the past 25 years, three-dimensional (3D) printing, a breakthrough layer-by-layer manufacturing technology that produces final parts directly from 3D model data, has taken off and transformed the treatment of bone defects by enabling personalized therapies with highly porous 3D-printed implants tailored to the patient. Therefore, to reduce the morbidities and complications associated with current treatment regimens, efforts have been made in translational research toward 3D-printed scaffolds to facilitate bone regeneration. Three-dimensional printed scaffolds should not only provide osteoconductive surfaces for cell attachment and subsequent bone formation but also provide physical support and containment of bone graft material during the regeneration process, enhancing bone ingrowth, while simultaneously, orthopaedic implants supply mechanical strength with rigid, stable external and/or internal fixation. In this perspective review, we focus on elaborating on the history of bone defect treatment methods and assessing current treatment approaches as well as recent developments, including existing evidence on the advantages and disadvantages of 3D-printed scaffolds for bone defect regeneration. Furthermore, it is evident that the regulatory framework and organization and financing of evidence-based clinical trials remains very complex, and new challenges for non-biodegradable and biodegradable 3D-printed scaffolds for bone regeneration are emerging that have not yet been sufficiently addressed, such as guideline development for specific surgical indications, clinically feasible design concepts for needed multicentre international preclinical and clinical trials, the current medico-legal status, and reimbursement. These challenges underscore the need for intensive exchange and open and honest debate among leaders in the field. This goal can be addressed in a well-planned and focused stakeholder workshop on the topic of patient-specific 3D-printed scaffolds for long bone defect regeneration, as proposed in this perspective review.

Femur reconstruction in 3D ultrasound for orthopedic surgery planning.

PURPOSE: Derotation varisation osteotomy of the proximal femur in pediatric patients usually relies on 2-dimensional X-ray imaging, as CT and MRI still are disadvantageous when applied in small children either due to a high radiation exposure or the need of anesthesia. This work presents a radiation-free non-invasive tool to 3D-reconstruct the femur surface and measure relevant angles for orthopedic diagnosis and surgery planning from 3D ultrasound scans instead. METHODS: Multiple tracked ultrasound recordings are segmented, registered and reconstructed to a 3D femur model allowing for manual measurements of caput-collum-diaphyseal (CCD) and femoral anteversion (FA) angles. Novel contributions include the design of a dedicated phantom model to mimic the application ex vivo, an iterative registration scheme to overcome movements of a relative tracker only attached to the skin, and a technique to obtain the angle measurements. RESULTS: We obtained sub-millimetric surface reconstruction accuracy from 3D ultrasound on a custom 3D-printed phantom model. On a pre-clinical pediatric patient cohort, angular measurement errors were [Formula: see text] and eventually [Formula: see text] for CCD and FA angles, respectively, both within the clinically acceptable range. To obtain these results, multiple refinements of the acquisition protocol were necessary, ultimately reaching success rates of up to 67% for achieving sufficient surface coverage and femur reconstructions that allow for geometric measurements. CONCLUSION: Given sufficient surface coverage of the femur, clinically acceptable characterization of femoral anatomy is feasible from non-invasive 3D ultrasound. The acquisition protocol requires leg repositioning, which can be overcome using the presented algorithm. In the future, improvements of the image processing pipeline and more extensive surface reconstruction error assessments could enable more personalized orthopedic surgery planning using cutting templates.

Total hip replacement in developmental dysplasia using an oval-shaped cementless press-fit cup.

PURPOSE: Acetabular roof deficiency due to subluxation of the femoral head (Hartofilakidis type II) increases the complexity of total hip arthroplasty. In these cases some form of support is usually required, to reach stable fixation of the acetabular component. Pursuing this aim, the oval-shaped cementless cranial socket could be an alternative to conventional treatment options. METHODS: Between 1998 and 2008, 37 patients (40 hips) underwent primary total hip arthroplasty using the cranial socket (mean follow-up 5.6 years, range 26 to 133 months). In a retrospective study we compared these clinical and radiological results with the results of a matched control group consisting of 35 patients (40 hips) treated with a standard cementless hemispherical cup in combination with bulk femoral autografting (mean follow-up 6.9 years, range 30 to 151 months). RESULTS: There were no statistically significant differences in the HHS (p=0.205) or the SF-36 (p=0.26) between both groups. There was no prosthesis failure due to septic or aseptic loosening. Time of surgery was significantly shorter in the cranial socket group (p<0.001). The acetabular component could be placed in the ideal rotational hip centre in 24 (60%) hips in the cranial socket group and 32 (80%) hips in the control group, respectively. CONCLUSIONS: Our study indicates, that the cranial socket can be an alternative treatment option for the reconstruction of acetabular deficiency in osteoarthritis secondary to developmental dysplasia.

Dental and Orthopaedic Implant Loosening: Overlap in Gene Expression Regulation.

Objectives: Endoprosthetic loosening still plays a major role in orthopaedic and dental surgery and includes various cellular immune processes within peri-implant tissues. Although the dental and orthopaedic processes vary in certain parts, the clinical question arises whether there are common immune regulators of implant loosening. Analyzing the key gene expressions common to both processes reveals the mechanisms of osteoclastogenesis within periprosthetic tissues of orthopaedic and dental origin. Methods: Donor peripheral blood mononuclear cells (PBMCs) and intraoperatively obtained periprosthetic fibroblast-like cells (PPFs) were (co-)cultured with [± macrophage-colony stimulating factor (MCSF) and Receptor Activator of NF-κB ligand (RANKL)] in transwell and monolayer culture systems and examined for osteoclastogenic regulations [MCSF, RANKL, osteoprotegerin (OPG), and tumor necrosis factor alpha (TNFα)] as well as the ability of bone resorption. Sequencing analysis compared dental and orthopaedic (co-)cultures. Results: Monolayer co-cultures of both origins expressed high levels of OPG, resulting in inhibition of osteolysis shown by resorption assay on dentin. The high OPG-expression, low RANKL/OPG ratios and a resulting inhibition of osteolysis were displayed by dental and orthopaedic PPFs in monolayer even in the presence of MCSF and RANKL, acting as osteoprotective and immunoregulatory cells. The osteoprotective function was only observed in monolayer cultures of dental and orthopaedic periprosthetic cells and downregulated in the transwell system. In transwell co-cultures of PBMCs/PPFs profound changes of gene expression, with a significant decrease of OPG (20-fold dental versus 100 fold orthopaedic), were identified. Within transwell cultures, which offer more in vivo like conditions, RANKL/OPG ratios displayed similar high levels to the original periprosthetic tissue. For dental and orthopaedic implant loosening, overlapping findings in principal component and heatmap analysis were identified. Conclusions: Thus, periprosthetic osteoclastogenesis may be a correlating immune process in orthopaedic and dental implant failure leading to comparable reactions with regard to osteoclast formation. The transwell cultures system may provide an in vivo like model for the exploration of orthopaedic and dental implant loosening.

A humanised rat model of osteosarcoma reveals ultrastructural differences between bone and mineralised tumour tissue.

Current xenograft animal models fail to accurately replicate the complexity of human bone disease. To gain translatable and clinically valuable data from animal models, new in vivo models need to be developed that mimic pivotal aspects of human bone physiology as well as its diseased state. Above all, an advanced bone disease model should promote the development of new treatment strategies and facilitate the conduction of common clinical interventional procedures. Here we describe the development and characterisation of an orthotopic humanised tissue-engineered osteosarcoma (OS) model in a recently genetically engineered x-linked severe combined immunodeficient (X-SCID) rat. For the first time in a genetically modified rat, our results show the successful implementation of an orthotopic humanised tissue-engineered bone niche supporting the growth of a human OS cell line including its metastatic spread to the lung. Moreover, we studied the inter- and intraspecies differences in ultrastructural composition of bone and calcified tissue produced by the tumour, pointing to the crucial role of humanised animal models.

Popliteal entrapment syndrome caused by fibular osteochondroma.

Osteochondromas are the most common tumors of bone. In adolescence, they usually present as a painless growing mass. Femoropopliteal vascular complications associated with an osteochondroma are rare, with most cases involving pseudoaneurysms. This report describes an exceptional case of a popliteal entrapment syndrome caused by a proximal fibular osteochondroma.