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Dirk Zajonz,1,2,* Florian Prager,1,* Melanie Edel,1,2 Robert Möbius,1,2 Alexandros Daikos,1 Johannes KM Fakler,1 Christoph Josten,1,2 Jürgen Kratzsch,3 Andreas Roth1,2 1Department of Orthopaedics, Trauma and Plastic Surgery, University Hospital Leipzig, Leipzig, Germany; 2ZESBO – Zentrum zur Erforschung der Stuetz- und Bewegungsorgane, Leipzig, Germany; 3Institute of Laboratory Medicine, Clinical Chemistry and Molecular Diagnostics, University of Leipzig, Leipzig, Germany *These authors contributed equally to this work Background: The importance of the vitamin D homeostasis in infections is already known. However, its significance in periprosthetic infections (PPIs) after total hip arthroplasty and total knee arthroplasty is largely unexplored. The aim of the study is to precisely analyze the vitamin D balance in patients with PPIs after total hip arthroplasty and total knee arthroplasty. Here, cases with primary endoprosthesis implants and aseptic loosening are used as comparison groups.Materials and methods: In this prospective matched-pair analysis, patients with PPI at the hip and knee joints were included in the study group (SG). The control groups (CGs) consisted of patients with primary implants (CG I) and who underwent replacement surgery due to aseptic loosening (CG II). In addition to 25 OH vitamin D3 and calcium, bone mineral and protein parameters were determined. An osteoporosis-specific questionnaire was collected.Results: There are no significant differences in the 25 OH-vitamin D levels between the SG (17.9±8.9) and both CGs (CG I: 16.8±6.90; CG II: 19.7±7.90). However, compared with the SG, significantly higher levels of calcium (Ca) and bone-specific alkaline phosphatase were found in both CGs in comparison with the SG. Significantly lower values concerning the protein balance in PPI were conspicuous. Acute PPI showed a significant reduction in 25 OH vitamin D3 compared with chronic infections (8.3±5.98 vs 21.6±8.40, P=0.002). Calcium and protein balance were also significantly reduced in acute PPIs.Conclusion: Acute PPIs of the hip and knee joints show a significantly reduced calcium and 25 OH vitamin D3 levels as well as lowered proteins (albumin and total protein) compared with chronic infections as well as primary endoprostheses and aseptic replacement operations. Substitution of vitamin D3 and calcium with simultaneous adaptation of the protein balance is recommended in all PPIs, especially in the acute PPI. Keywords: periprosthetic infection, protein deficiency, THA, TKA, vitamin D deficiency

Background: Brain biopsy is required for the accurate specification and further diagnosis of intracranial findings. The conventional stereotactic frames are used clinically for biopsies and offer the highest possible precision. Unfortunately, they come with some insurmountable technical and logistical limitations. The aim of the present work is to determine the clinical precision in the needle biopsy of the human brain using a new patient-specific stereotactic navigation device based on 3D printing., Methods: MRI data sets of human cadaver heads were used to plan 32 intracranial virtual biopsy targets located in different brain regions. Based on these data, 16 individualized stereotactic frames were 3D-printed. After the intraoperative application of the stereotactic device to the cadaver's head, the actual needle position was verified by postoperative CT., Results: Thirty-two brain areas were successfully biopsied. The target point accuracy was 1.05 ± 0.63 mm, which represents the difference between the planned and real target points. The largest target point deviation was in the coronal plane at 0.60 mm; the smallest was in the transverse plane (0.45 mm)., Conclusions: Three-dimensional-printed, personalized stereotactic frames or platforms are an alternative to the commonly used frame-based and frameless stereotactic systems. They are particularly advantageous in terms of accuracy, reduced medical imaging, and significantly simplified intraoperative handling.

The use of stereotactic frames is a common practice in neurosurgical interventions such as brain biopsy and deep brain stimulation. However, conventional stereotactic frames have been shown to require modification and adaptation regarding patient and surgeon comfort as well as the increasing demand for individualized medical treatment. To meet these requirements for carrying out state-of-the-art neurosurgery, a 3D print-based, patient-specific stereotactic system was developed and examined for technical accuracy. Sixteen patient-specific frames, each with two target points, were additively manufactured from PA12 using the Multi Jet Fusion process. The 32 target points aim to maximize the variability of biopsy targets and depths for tissue sample retrieval in the brain. Following manufacturing, the frames were measured three-dimensionally using an optical scanner. The frames underwent an autoclave sterilization process prior to rescanning. The scan-generated models were compared with the planned CAD models and the deviation of the planned target points in the XY-plane, Z-direction and in the resulting direction were determined. Significantly lower ( p < 0.01) deviations were observed when comparing CAD vs. print and print vs. sterile in the Z-direction (0.17 mm and 0.06 mm, respectively) than in the XY-plane (0.46 mm and 0.16 mm, respectively). The resulting target point deviation (0.51 mm) and the XY-plane (0.46 mm) are significantly higher ( p < 0.01) in the CAD vs. print comparison than in the print vs. sterile comparison (0.18 mm and 0.16 mm, respectively). On average, the results from the 32 target positions examined exceeded the clinically required accuracy for a brain biopsy (2 mm) by more than four times. The patient-specific stereotaxic frames meet the requirements of modern neurosurgical navigation and make no compromises when it comes to accuracy. In addition, the material is suitable for autoclave sterilization due to resistance to distortion.

Background: Optical neuronavigation systems using infrared light to create a virtual reality image of the brain allow the surgeon to track instruments in real time. Due to the high vulnerability of the brain, neurosurgical interventions must be performed with a high precision. The aim of the experimental cadaveric study was to determine the application accuracy of a frameless optical neuronavigation system as guide for craniotomies by determining the target point deviation of predefined target points at the skull surface in the area of access to the cerebrum, cerebellum and the pituitary fossa. On each of the five canine cadaver heads ten target points were marked in a preoperative computed tomography (CT) scan. These target points were found on the cadaver skulls using the optical neuronavigation system. Then a small drill hole (1.5 mm) was drilled at these points. Subsequently, another CT scan was made. Both CT data sets were fused into the neuronavigation software, and the actual target point coordinates were identified. The target point deviation was determined as the difference between the planned and drilled target point coordinates. The calculated deviation was compared between two observers., Results: The analysis of the target point accuracies of all dogs in both observers taken together showed a median target point deviation of 1.57 mm (range: 0.42 to 5.14 mm). No significant differences were found between the observers or the different areas of target regions., Conclusion: The application accuracy of the described system is similar to the accuracy of other optical neuronavigation systems previously described in veterinary medicine, in which mean values of 1.79 to 4.3 mm and median target point deviations of 0.79 to 3.53 mm were determined., (© 2023. The Author(s).)

The aim of the project was to develop a patient-specific stereotactic system that allows simultaneous and thus time-saving treatment of both cerebral hemispheres and that contains all spatial axes and can be used as a disposable product. Furthermore, the goal was to reduce the size and weight of the stereotactic system compared to conventional systems to keep the strain on the patient, who is awake during the operation, to a minimum. In addition, the currently mandatory computed tomography should be avoided in order not to expose the patient to harmful X-ray radiation as well as to eliminate errors in the fusion of CT and MRI data.3D printing best meets the requirements in terms of size and weight: on the one hand, the use of plastic has considerable potential for weight reduction. On the other hand, the free choice of the individual components offers the possibility to optimize the size and shape of the stereotactic system and to adapt it to the individual circumstances while maintaining the same precision. The all-in-one stereotactic system was produced by means of the Multi Jet Fusion process. As a result, the components are highly precise, stable in use, lightweight and sterilizable. The number of individual components and interfaces, which in their interaction are potential sources of error, was significantly reduced. In addition, on-site manufacturing leads to faster availability of the system.Within the project, a patient-specific stereotaxy system was developed, printed, and assembled, which enables the execution of deep brain stimulation via only three bone anchors located on the skull. Pre-developed MRI markers, which can be screwed directly onto the bone anchors via the sleeves, eliminate the need for a CT scan completely. The fusion of the data, which is no longer required, suggests an improvement in target accuracy., (© 2023. Springer Nature Switzerland AG.)

Introduction: Individuals with Parkinsonian disorders often face limited access to specialized physiotherapy and movement training due to staff shortages and increasing disease incidence, resulting in a rapid decline in mobility and feelings of despair. Addressing these challenges requires allocating adequate resources and implementing specialized training programs to ensure comprehensive care and support. Regarding these problems, a computer software was invented that might serve as an additional home-based extension to conventional physiotherapy., Methods: The trial took place in a rehabilitation center where every patient received equivalent treatment apart from the training program that was set up to be investigated over 3 weeks. Seventy four Patients were included and randomized between two intervention and one control group. Intervention group 1 (IG1) trained with the computer-based system two times a week while Intervention group 2 (IG2) received five training sessions a week. Using the markerless Microsoft Kinect® camera, participants controlled a digital avatar with their own body movements. UPDRS-III and Clinical measurements were performed before and after the three-week period., Results: Patients in all groups improved in UPDRS-III pre and post intervention whereas reduction rates were higher for IG1 (-10.89%) and IG2 (-14.04%) than for CG (-7.74%). Differences between the groups were not significant (value of ps CG/IG1 0.225, CG/IG2 0.347). Growth rates for the arm abduction angle were significantly higher in IG1 (11.6%) and IG2 (9.97%) than in CG (1.87%) (value of ps CG/IG1 0.006 and CG/IG2 0.018), as was the 5-steps-distance (CG 10.86% vs. IG1 24.5% vs. UG2 26.22%, value of ps CG/IG1 0.011 and CG/IG2 0.031)., Discussion: The study shows the beneficial effects of computer-based training and substantiates the assumption of a similar impact in a home-based setting. The utilized software is feasible for such interventions and meets with the patient's approval. Group dynamics seem to have an additional supporting effect for the aspired objective of improving mobility and should be seen as an essential aspect of video games in therapy., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Barth, Möbius, Themann, Güresir, Matzke, Winkler and Grunert.)

Objective  The aim of this work was the development of an augmented reality system including the functionality of conventional surgical navigation systems. Methods  An application software for the Augmented Reality System HoloLens 2 from Microsoft was developed. It detects the position of the patient as well as position of surgical instruments in real time and displays it within the two-dimensional (2D) magnetic resonance imaging or computed tomography (CT) images. The surgical pointer instrument, including a pattern that is recognized by the HoloLens 2 sensors, was created with three-dimensional (3D) printing. The technical concept was demonstrated at a cadaver skull to identify anatomical landmarks. Results  With the help of the HoloLens 2 and its sensors, the real-time position of the surgical pointer instrument could be shown. The position of the 3D-printed pointer with colored pattern could be recognized within 2D-CT images when stationary and in motion at a cadaver skull. Feasibility could be demonstrated for the clinical application of transsphenoidal pituitary surgery. Conclusion  The HoloLens 2 has a high potential for use as a surgical navigation system. With subsequent studies, a further accuracy evaluation will be performed receiving valid data for comparison with conventional surgical navigation systems. In addition to transsphenoidal pituitary surgery, it could be also applied for other surgical disciplines., Competing Interests: Conflict of Interest None declared., (Thieme. All rights reserved.)

Three-dimensional (3D) printing techniques for patient-individual medicine has found its way into veterinary neurosurgery. Because of the high accuracy of 3D printed specific neurosurgical navigation devices, it seems to be a safe and reliable option to use patient-individual constructions for sampling brain tissue. Due to the complexity and vulnerability of the brain a particularly precise and safe procedure is required. In a recent cadaver study a better accuracy for the 3D printed MRI-based patient individual stereotactic brain biopsy device for dogs is determined compared to the accuracies of other biopsy systems which are currently used in veterinary medicine. This case report describes the clinical use of this 3D printed MRI-based patient individual brain biopsy device for brain sampling in three dogs. The system was characterized by a simple handling. Furthermore, it was an effective and reliable tool to gain diagnostic brain biopsy samples in dogs with no significant side effects., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Gutmann, Flegel, Müller, Möbius, Matiasek, König, Winkler and Grunert.)

Background: Intraoperative proximal femoral fractures (IPFF) are relevant complications during total hip arthroplasty. Fixation using cerclage wires (CW) represents a minimally-invasive technique to address these fractures through the same surgical approach. The goal of treatment is to mobilise the patient as early as possible, which requires high primary stability. This study aimed to compare different cerclage wire configurations fixing IPFF with regard to biomechanical primary stability., Methods: Standardised IPFF (type II, Modified Mallory Classification) were created in human fresh frozen femora and were fixed either by two or three CW (1.6 mm, stainless steel). All cadaveric specimens (n = 42) were randomised to different groups (quasi-static, dynamic) or subgroups (2 CW, 3 CW) stratified by bone mineral density determined by Dual Energy X-ray Absorptiometry. Using a biomechanical testing setup, quasi-static and dynamic cyclic failure tests were carried out. Cyclic loading started from 200 N to 500 N at 1 Hz with increasing peak load by 250 N every 100 cycles until failure occurred or maximum load (5250 N) reached. The change of fracture gap size was optically captured., Results: No significant differences in failure load after quasi-static (p = 0.701) or dynamic cyclic loading (p = 0.132) were found between the experimental groups. In the quasi-static load testing, all constructs resisted 250% of the body weight (BW) of their corresponding body donor. In the dynamic cyclic load testing, all but one construct (treated by 3 CW) resisted 250% BW., Conclusions: Based on this in vitro data, both two and three CW provided sufficient primary stability according to the predefined minimum failure load (250% BW) to resist. The authors recommend the treatment using two CW because it reduces the risk of vascular injury and shortens procedure time., (© 2022. The Author(s).)

Background: All current total hip arthroplasty (THA) systems are modular in design. Only during the operation femoral head and stem get connected by a Morse taper junction. The junction is realized by hammer blows from the surgeon. Decisive for the junction strength is the maximum force acting once in the direction of the neck axis, which is mainly influenced by the applied impulse and surrounding soft tissues. This leads to large differences in assembly forces between the surgeries. This study aimed to quantify the assembly forces of different surgeons under influence of surrounding soft tissue., Methods: First, a measuring system, consisting of a prosthesis and a hammer, was developed. Both components are equipped with a piezoelectric force sensor. Initially, in situ experiments on human cadavers were carried out using this system in order to determine the actual assembly forces and to characterize the influence of human soft tissues. Afterwards, an in vitro model in the form of an artificial femur (Sawbones Europe AB, Malmo, Sweden) with implanted measuring stem embedded in gelatine was developed. The gelatine mixture was chosen in such a way that assembly forces applied to the model corresponded to those in situ. A study involving 31 surgeons was carried out on the aforementioned in vitro model, in which the assembly forces were determined., Results: A model was developed, with the influence of human soft tissues being taken into account. The assembly forces measured on the in vitro model were, on average, 2037.2 N ± 724.9 N, ranging from 822.5 N to 3835.2 N. The comparison among the surgeons showed no significant differences in sex (P = 0.09), work experience (P = 0.71) and number of THAs performed per year (P = 0.69)., Conclusions: All measured assembly forces were below 4 kN, which is recommended in the literature. This could lead to increased corrosion following fretting in the head-neck interface. In addition, there was a very wide range of assembly forces among the surgeons, although other influencing factors such as different implant sizes or materials were not taken into account. To ensure optimal assembly force, the impaction should be standardized, e.g., by using an appropriate surgical instrument., (© 2021. The Author(s).)

Background: Malnutrition caused by protein and vitamin deficiencies is a significant negative prognostic factor in surgical wound healing disorders and infections. Particularly in elective surgery, preoperative compensation of deficiencies is advisable to avoid negative postoperative consequences. This study examined the nutritional and protein balance of patients with periprosthetic hip and knee joint infections., Material and Methods: Patients with periprosthetic hip or knee joint infections constituted the study group (SG). Control group I (CG I) included patients with primary implants and CG II included patients who required revision surgery because of aseptic loosening. Relevant nutritional and protein parameters were determined via analysis of peripheral venous blood samples. In addition, a questionnaire was used to evaluate the nutritional and eating patterns of all patients. The nutritional risk screening (NRS) 2002 score and body mass index (BMI) were also calculated for all participants., Results: Differences were found in the albumin level (SG: 36.23 ± 7.34, CG I: 44.37 ± 3.32, p < 0.001, CG II: 44.06 ± 4.24, p < 0.001) and total protein in serum (SG: 65.42 ± 8.66, CG I: 70.80 ± 5.33, p = 0.004, CG II: 71.22 ± 5.21, p = 0.004). The number of patients with lowered albumin levels (SG 19/61, CG I 1/78, CG II 2/55) and total protein in serum (SG: 12/61, CG I 5/78, CG II 2/55) also showed considerable variation. The number of patients with a NRS 2002 score ≥3 differed significantly between SG and both CGs (SG: 5/61, CG I 1/78, CG II 0/55); however, these differences could not be confirmed using BMI., Conclusion: As expected, lowered albumin and total protein levels were observed in PJI due to the acute phase reaction. The NRS can be performed to exclude nutritional deficiency, which cannot be excluded based on BMI. In cases of periprosthetic joint infection it is reasonable to compensate the nutritional deficiency with dietary supplements.

Background: Knee joint arthrodesis is an established treatment for periprosthetic infections (PPI) providing stability and pain relief. In this study the outcome after arthrodesis of the knee joint for persistent infections was compared and evaluated depending on the surgical procedure (intramedullary vs. extramedullary)., Material and Methods: In a retrospective case analysis, all patients who underwent knee joint arthrodesis between 1 January 2010 and 31 December 2016 were identified and divided into two groups: IMA and EMA. All patients were examined clinically and radiologically and the patient files were evaluated. In addition, the FIM score, the LEFS, the WHOQOL-BREF and NRS were evaluated., Results: The median LEFS score for the IMA group was 26 points and in the EMA group 2 points (p = 0.03). The IMA patients showed a median pain scale at rest of 0 and during exercise of 2. The EMA group recorded a pain scale of 3 at rest and 5 during exercise (p = 0.28 at rest; p = 0.43 during exercise). In the IMA group the median postsurgical leg length difference was -2.0 cm and -2.5 cm in the EMA group (p = 0.31). At the end of the follow-up examinations, the FIM score of patients in the IMA group was 74.5 points and 22 points in the EMA group (p = 0.07)., Conclusion: The study showed that no arthrodesis procedure is obviously superior with respect to the postoperative outcome. The IMA combines advantages especially in the early phase after surgery in terms of function as well as patient comfort and is therefore currently the procedure of choice. The attending physician should be familiar with the advantages and disadvantages of the various procedures in order to be able to make an individual decision and thus maximize the chance of treatment success.

Introduction: In addition to abrasion-induced osteolysis and ensuing instabilities, the polyethylene (PE) abrasion of total hip arthroplasty (THA) inlays can also cause gait instability due to the decentralization of the hip joint. The current literature yields, as yet, insufficient findings whether these two factors are linked directly or indirectly to a higher risk for periprosthetic proximal femoral fractures (PPFF). The aim of our retrospective evaluation is to analyse the impact of PE abrasion on the pathology of PPFF in patients with THA., Material and Methods: The retrospective evaluation comprises all PPFF in patients with THA in the period from 01/2010 up to 12/2016. The study group (SG) included 66 cases (n = 66). The control group (CG) was comprised of patients with asymptomatic THA (n = 66), who were treated by our outpatient department including routine check-ups and X-ray examinations. We used the matched-pair methodology to scale the period of postsurgical care of the CG to the lifetime of the implant up to PPFF in the SG. We included epidemiologic data, radiological femoral head decentralization, osteolysis (Gruen classification), instabilities, acetabular cup position, and implant properties in our analysis. For the SG, we also included intra-operative signs of abrasion., Findings: The SG showed significantly higher numbers of decentralized THA as signs of inlay erosion with 73% compared to only 41% in the CG (p > 0.001). The SG showed 1 ± 0.68 mm hip joint decentralization as to 0.5 ± 0.59 mm in the CG (p = 0.004). We found significantly more cases of osteolysis in the SG (n = 25) than in the CG (n = 13) (p = 0.003). We found no notable differences in acetabular cup inclination or anteversion as well as cup size. However, differences were significant in femoral head size (SG 32 ± 2.3 mm, CG 36 ± 2.4 mm; p = 0.042) and head material. We found more widespread use of metal femoral heads in the SG than in the CG (SG 1:1, CG 1:21; p = 0.001)., Conclusion: PPFF patients showed significantly higher rates of inlay erosion, resulting in femoral head decentralization and osteolysis. The higher rate of fracture is likely caused by the increasing instability of the implant fixation due to abrasion-induced osteolysis and the associated degradation of bone quality. It is conceivable that the abrasion and decentralization of the THA can also lead to gait instability, and thus, a higher proneness to falls. Gait instability can also be aggravated by increased granulation tissue and effusion due to the inlay abrasion. Although this cannot be substantiated by the investigation. In patients with decentralization of the THA and osteolysis, a radiological follow-up should be performed, and in case of gait instability (femoral head and) inlay replacements should be considered.