Moritz Florian Mayr

Background: Frailty and sarcopenia are overlapping syndromes that increase adverse outcomes in older adults. Computed tomography (CT) is a reference standard for body composition analysis, but manual segmentation is time-consuming. This exploratory study used a fully automated deep learning model (DLM) to investigate associations between CT-derived muscle quality and quantity and clinical frailty. Methods: We performed a retrospective, cross-sectional secondary analysis of 53 geriatric surgical patients (mean age 77.4 ± 4.4 years). A DLM segmented skeletal muscle (SM), subcutaneous and visceral adipose tissue at the third lumbar vertebral level. Intermuscular adipose tissue (IMAT) was quantified exclusively within the erector spinae muscle and is therefore reported as a surrogate marker of trunk muscle quality rather than whole-muscle myosteatosis. Frailty was assessed with the Clinical Frailty Scale (CFS), handgrip strength and the Timed Up and Go (TUG) test. Because functional testing was incomplete, effective sample sizes varied ( n = 21–53) and are reported for every model. Results: In the total cohort, a higher IMAT Index was associated with lower handgrip strength ( ρ = −0.434, p = 0.004, n = 43) and remained independent after adjustment for age, sex, BMI and ASA status (B = −1.808, 95% CI −2.994 to −0.622, p = 0.004, n = 42). Its association with the CFS was borderline univariately ( ρ = 0.273, p = 0.051, n = 52) and absent after adjustment ( p = 0.184, n = 51). Neither index was independently associated with TUG performance ( p = 0.134 and p = 0.071, n = 25). In an exploratory sex-stratified analysis, the IMAT Index correlated with the CFS in women ( ρ = 0.727, p < 0.001, n = 19) but not in men. Because the female subgroup was small ( n = 20), no sex-stratified regression or interaction test was performed. Conclusions: In this small, retrospective, cross-sectional cohort, an erector-spinae-based IMAT Index was associated with handgrip strength but not independently with global clinical frailty. Automated opportunistic CT analysis may therefore identify specific muscle weakness rather than global frailty. The observed sex differences are hypothesis-generating and require confirmation in larger, adequately powered longitudinal studies.

Purpose: Distinguishing physiological meniscus mobility from pathological extrusion remains a clinical challenge, particularly regarding the prevention of osteoarthritis. While cadaveric studies suggest that meniscectomy increases contact stress, the in vivo dynamics of the healthy meniscus under load—specifically the role of the meniscotibial (coronary) ligament—remain poorly defined. This study aimed to establish a physiological reference standard for load transmission and contact area kinematics in the healthy knee. Methods: In a biomechanical MRI study, nine healthy male subjects underwent high-resolution 3T MRI with prospective motion correction. Knee joints were scanned in an unloaded state and under a physiological axial load of 400 N. We performed 3D segmentation to quantify changes in cartilage-to-cartilage and cartilage-to-meniscus contact areas, differentiating between femoral and tibial interfaces. Results: Axial loading significantly increased the direct cartilage-to-cartilage contact area, with a predominant increase in the medial compartment (+ 15.0%) compared to the lateral compartment (+ 6.7%), reflecting the physiological adduction moment. Conversely, the overall meniscus-to-cartilage contact area decreased. A detailed compartmental analysis revealed a distinct kinematic pattern: while the femoral-meniscal contact area significantly decreased due to relative motion, the tibial-meniscal contact area remained stable. Conclusion: This study defines the in vivo healthy baseline of knee contact mechanics. The results demonstrate that under physiological load, the healthy meniscus undergoes controlled radial displacement to facilitate direct cartilage contact. Crucially, the stability of the tibial contact area supports the hypothesis that the meniscotibial (coronary) ligament acts as a primary anchor, preventing excessive extrusion at the tibial interface. These data serve as a vital benchmark for evaluating meniscus repair techniques and differentiating physiological mobility from pathological failure.

Implant–associated infections and aseptic loosening of prosthesis due to insufficient secondary stability continue to present a challenging issue in arthroplasty. Potential solutions include bioactive coatings to promote osseointegration. With this in mind, this study aims to investigate and compare thin bioactive and bioresorbable β-tricalcium phosphate (β-TCP) and calcium alka-li orthophosphate (GB14) coatings, both produced via high velocity suspension flame spraying. To achieve an additional antibacterial effect and to prevent infections through aerosolized contamination, Cu-doped β-TCP supraparticles (SP) are incorporated into the coatings. β-TCP and GB14 coatings with 0.5 wt.% Cu-doped β-TCP SP each were investigated. According to ISO EN 10993–14, a degradation test was performed in TRIS-buffer at pH 7.4 over 120 h. Biocompatibility testing was performed on human osteoblasts using live/dead staining on days 1, 3 and 7 to simultaneously visualize viable and non-viable cells, while cytotoxicity was assessed over a 3 d period with the cytotoxicity assay. To evaluate the antibacterial efficacy, safe airborne antibacterial assays using S. aureus and E. coli were performed. Our investigations demonstrate that Cu is released from the coatings over a period of 120 h. The released Cu-amount results in a significant reduction in colony forming units across all coatings, while only negligibly imparing the behavior of the human osteoblasts. Both coatings exhibit high biocompatibility, with cell counts varying depending on the amount of Cu released. Cytotoxicity testing showed no cytotoxic effects for the samples examined.

Background: Rupture of the ACL is a common injury among men and women athletes. While planning the surgical ACL reconstruction procedure, the eventual graft’s diameter is extremely important. Many parameters are therefore evaluated pre-surgery to ensure access to reliable data for estimating the graft diameter. Considering this, magnetic resonance imaging (MRI), particularly qualitative analyses of the hamstring tendons, offers a promising approach. Methods: In a retrospective analysis, we carried out 3D segmentation of the gracilis (GT) and semitendinosus tendon (ST) utilizing MRI with varying slice thicknesses and field strengths. The cross-sectional area (CSA) was calculated on different levels (by relying on the models we had thus created) to generate a mean of CSA with six specific segments. We then correlated the mean CSA with the diameter of the graft measured during surgery. Results: A total of 32 patients were included (12 female, 20 male) in this retrospective analysis. We observed the largest CSA in segment 10 mm–0 (16.8 ± 6.1) with differences between men and women. The graft size and tendon diameter correlated significantly in all segments throughout our study cohort. The strongest correlation was apparent in the segment 10 mm–0 (r = 0.552). Conclusions: MRI-based 3D segmentation and the STGT CSA represent a reliable method for estimating preoperatively a quadrupled hamstring graft diameter. The 10 mm–0 mm segment above the joint line showed a strong correlation, making it an ideal reference for graft planning.

Implant-associated infections and aseptic loosening of prosthesis due to insufficient secondary stability continue to present a challenging issue in arthroplasty. Potential solutions include bioactive coatings to promote osseointegration. With this in mind, this project aims to investigate and compare thin bioactive and bioresorbable β-tricalcium phosphate and calcium alkaliphosphate coatings, both produced via High Velocity Suspension Flame Spraying. To achieve an additional antibacterial effect, Cu-doped TCP supraparticles are incorporated into the coatings. β-TCP and GB14 coatings with 0.5 wt.% Cu-doped TCP supraparticles each were investigated. According to ISO EN 10993-14, a degradation test was performed in TRIS-buffer at pH 7.4 over 120 hours. Biocompatibility tests were performed on human osteoblasts. Live/Dead staining was performed on day 1, 3 and 7 to visualize live and dead cells. Furthermore, cytotoxicity was evaluated over 3 days using the LDH assay. To determine the antibacterial efficacy Safe Airborne Antibacterial Assays using Staphylococcus aureus and Escherichia coli were performed. Our investigations demonstrate that copper is released from the coatings over a period of 120 hours. Both coatings exhibit good biocompatibility, with cell counts varying depending on the amount of Cu released. Cytotoxicity testing showed no cytotoxic effects for the samples examined. Cu-doping of the coatings achieved a significant reduction in colony-forming units across all coatings.

Background: The surgical treatment of adolescent idiopathic scoliosis (AIS) is influenced by factors such as skeletal maturity, curve magnitude, progression, and spinal flexibility. The assessment of spinal flexibility is crucial for surgical planning; supine bending radiographs are commonly used but there is no consensus on the optimal technique. Fulcrum bending radiographs (FBRs) have shown better prediction of post-surgery correction compared to supine bending radiographs. New radiological techniques allow a significant reduction in radiation exposure. This study aims to compare spinal flexibility assessment and radiation exposure between FBRs and standing side-bending radiographs (SSRs) using biplanar stereoradiography. Materials and Methods: Twenty-five consecutive AIS patients scheduled for surgery were included in this prospective cohort study. Exclusion criteria were non-idiopathic etiology, age younger than 12 years, and older than 18 years. Pre-surgery FBRs and SSRs were performed, and the Cobb angles were measured. Flexibility and correction rates were calculated. Dose–area products (DAPs) were recorded. Statistical analysis was conducted using the Wilcoxon signed-rank test and Spearman correlation. Results: The mean pre-surgery Cobb angle of the thoracic curve was 66.3°. The FBR was superior to SSR for assessing flexibility for thoracic curves and provided a better prediction for post-surgery correction. There was no significant difference in lumbar curves between FBR and SSR. The mean DAP for SSRs was 0.81 Gy*cm² compared to 3.42 Gy*cm² for FBR, indicating a lower radiation exposure using SSRs. Conclusions: FBRs are superior for flexibility assessment of thoracic curves in AIS and offers a better prediction of post-surgery correction compared to SSRs. However, FBR is associated with a higher radiation exposure.

Background: In ACL reconstruction, it is desirable to assess preoperatively whether a sufficient graft diameter can be achieved with the planned tendon graft. The present study investigated the effect of the location of the cross-sectional area (CSA) measurement of the hamstring tendons in preoperative MRI on the correlation of the CSA with the intraoperative graft diameter. In addition, we analyzed whether the measurement results of examiners with different skill levels were comparable. Methods: A total of 32 subjects undergoing a single bundle ACL reconstruction using an autologous ipsilateral quadrupled hamstring graft (STGT) were included. The CSA of the semitendinosus and gracilis tendon was determined in preoperative MRI on six defined levels by three examiners. The intraclass correlation coefficient between the measurements of these observers was determined. The correlation between the sum of the CSA of both tendons (CSA STGT) and the graft diameter was investigated. Results: The interrater reliability was excellent on most of the investigated levels. A significant correlation between CSA STGT and the graft diameter was seen on all levels. The strongest correlation was found on the level 10 mm above the joint line. Conclusions: The measurement of the CSA STGT in the preoperative MRI 10 mm above the joint line enabled a good assessment of the achievable graft diameter in ACL reconstruction, independent of the examiners’ training level.

Purpose: We aim to compare radiation exposure and implant-related complications of the freehand (FH) technique versus intraoperative image-guided navigation (IN) for pedicle screw placement in adolescent idiopathic scoliosis (AIS) and estimate associated lifetime attributable cancer risks. Methods: A retrospective analysis of prospectively collected data from 40 consecutive AIS patients treated with pedicle screw instrumentation using the FH technique was performed. The dose area product (DAP) and effective dose (ED) were calculated. Screw-related complications were analysed, and the age- and gender-specific lifetime attributable cancer risks were estimated. The results were compared to previously published data on IN used during surgery for AIS. Results: There were no implant-related complications in our cohort. Implant density was 86.6%. The mean Cobb angle of the main curve was 75.2° (SD ± 17.7) preoperatively and 27.7° (SD ± 10.8) postoperatively. The mean ED of our cohort and published data for the FH technique was significantly lower compared to published data on the IN technique (p < 0.001). The risk for radiogenic cancer for our FH technique AIS cohort was 0.0014% for male patients and 0.0029% for female patients. Corresponding risks for IN were significantly higher (p < 0.001), ranging from 0.0071 to 0.124% and from 0.0144 to 0.253% for male and female patients, respectively. Conclusion: The routine use of intraoperative navigation in AIS surgery does not necessarily reduce implant-related complications but may increase radiation exposure to the patient.

Background: The treatment of grafts with vancomycin for ligament reconstruction in knee surgery is the current standard. However, high antibiotic concentrations have chondrotoxic effects. Purpose: To test the chondrotoxicity of clindamycin, gentamicin and vancomycin in comparable concentrations. In vitro and in vivo effective concentrations hugely vary from drug to drug. To allow for comparisons between these three commonly used antibiotics, the concentration ranges frequently used in orthopedic surgical settings were tested. Study Design: Controlled laboratory study. Methods: Human cartilage from 10 specimens was used to isolate chondrocytes. The chondrocytes were treated with clindamycin (1 mg/mL and 0.5 mg/mL), gentamicin (10 mg/mL and 5 mg/mL) or vancomycin (10 mg/mL and 5 mg/mL), at concentrations used for preoperative infection prophylaxis in ligament surgery. Observations were taken over a period of 7 days. A control of untreated chondrocytes was included. To test the chondrotoxicity, a lactate dehydrogenase (LDH) test and a water-soluble tetrazolium salt (WST-1) assay were performed on days 1, 3 and 7. In addition, microscopic examinations were performed after fluorescence staining of the cells at the same time intervals. Results: All samples showed a reasonable vitality of the cartilage cells after 72 h. However, clindamycin and gentamicin both showed higher chondrotoxicity in all investigations compared to vancomycin. After a period of 7 days, only chondrocytes treated with vancomycin showed reasonable vitality. Conclusions: The preoperative treatment of ligament grafts with vancomycin is the most reasonable method for infection prophylaxis, in accordance with the current study results regarding chondrotoxicity; however, clindamycin and gentamicin cover a wider anti-bacterial spectrum. Clinical Relevance: The prophylactic antibiotic treatment of ligament grafts at concentrations of 5 mg/mL or 10 mg/mL vancomycin is justifiable and reasonable. In specific cases, even the use of gentamicin and clindamycin is appropriate.