Georgi Iwan Wassilew

Aims: Periacetabular osteotomy (PAO) is the primary surgical treatment for developmental dysplasia of the hip (DDH), providing considerable pain relief and improved joint function. Return to sport (RTS) is a key outcome for young, active patients. This study aimed to identify preoperative predictors of RTS timing and develop a machine-learning-based prediction model to optimize patient counselling.Methods: This retrospective analysis of prospectively collected data included 235 patients who underwent PAO between January 2019 and December 2023. Preoperative variables, including demographic, functional, and psychological assessments, were analyzed. RTS was assessed at three, six, and 12 months postoperatively. Logistic regression with recursive feature elimination and a conditional inference tree (ctree) model were used to identify predictors of RTS.Results: At three months, 102 patients (43%) had returned to sports, increasing to 182 (77%) at six months and 223 (95%) at 12 months. Key predictors of early RTS included the minimally invasive surgical approach, higher preoperative physical activity (≥ two sessions/week), lower anxiety scores, and higher Hip disability and Osteoarthritis Outcome Score (HOOS) pain scores. Male sex and older age were associated with delayed RTS. The ctree model stratified patients based on their likelihood of early RTS, providing an individualized prognosis.Conclusion: PAO enables early RTS in over 90% of patients within the first year. The use of a minimally invasive approach allowing immediate active hip flexion, higher preoperative activity levels, and lower anxiety scores significantly improves RTS timing. The machine-learning model provides precise, individualized RTS predictions, offering a valuable tool for patient counselling and rehabilitation planning.Cite this article: Bone Jt Open 2025;6(6 Supple B):33–42.

Introduction: The dynamic lumbopelvic interaction has gained increasing importance in hip-preserving surgery, even though the coexistence of lumbopelvic malalignment with pre-arthritic hip deformities has been poorly studied. This study aimed to examine (I) the frequency of static and functional lumbopelvic malalignment (II) and to compare the lumbopelvic alignment between symptomatic mild to severe hip dysplasia (HD) and impingement-driven acetabular retroversion (AR). Methods: Sagittal lumbopelvic radiographs were reviewed in standing, relaxed-seated and deep-seated position for pelvic incidence (PI), pelvic tilt (PT), lumbar lordosis (LL), and sacral slope (SS). Static lumbopelvic alignment was classified as “Flatback”, “Normal”, or “Hyperlordotic” and functional lumbopelvic alignment was categorized as “Stiff”, “Normal”, and “Hypermobile”. Static and functional (Δ between the above-mentioned positions) lumbopelvic parameters were compared among HD, borderline hip dysplasia (BHD), and AR. Results: Ninety-eight patients undergoing hip-preserving surgery for HD ( n = 47), BHD ( n = 36), and AR ( n = 15) were prospectively enrolled. Static lumbopelvic malalignment occurred in 44.9% of patients (44/98), with “Hyperlordotic” alignment being the most frequent (36/44). Additionally, 28.6% of patients (28/98) exhibited functional lumbopelvic malalignment. Static lumbopelvic parameters showed differences between hip instability and impingement, with lower PI (42° vs. 57.3°, p = 0.001; 42° vs. 53.7°, p = 0.01) and PT (5.6° vs. 15.8°, p < 0.001; 5.6° vs. 12.4°, p = 0.01) in AR patients compared to HD and BHD in standing position. Moreover, SS was significantly lower in AR (40.9° vs. 50.1°, p = 0.02) and BHD (43.8° vs. 50.1°, p = 0.05) compared to HD in deep-seated position. Significant differences in functional lumbopelvic parameters were observed only between HD and BHD in PT (Δ standing – deep-seated position, 7.1° vs. -1.2°, p = 0.04). Conclusion: Static and functional lumbopelvic malalignment is prevalent in patients with pre-arthritic hip deformities. While static lumbopelvic parameters vary between instability- and impingement-driven hip deformities, functional lumbopelvic alignment is quite similar among HD, BHD, and AR.

Implantate für den künstlichen Gelenkersatz und die Versorgung von Knochenbrüchen werden meist gut vertragen. Für mögliche Komplikationen stehen interdisziplinäre Diagnostikmaßnahmen zur Verfügung. Eine Vielzahl an Studien wie auch Registerdaten geben Überblicksinformationen. Metallallergie wird als Problemauslöser kontrovers diskutiert, da klare Überblicksdaten fehlen. So ist „Implantatallergie“ meist eine Ausschlussdiagnose. Article published online: 04 February 2025 © 2025. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany

Aims: Periacetabular osteotomy (PAO) is well established for acetabular reorientation and has shown successful improvement in patient-reported outcome measures (PROMs). Nevertheless, studies focusing on postoperative outcomes related to patient individual factors are still underrepresented. Therefore, this study aimed to analyze the functional outcome and activity level in relation to patient sex with a minimum follow-up of two years after PAO for mild to severe hip dysplasia.Methods: A single-centre study was conducted, enrolling patients undergoing PAO and completing a preoperative and postoperative radiological and clinical outcome assessment. The PROMs were assessed using the modified Harris Hip Score (mHHS), the Hip disability and Osteoarthritis Outcome Score (HOOS) with the subscales for pain, sport, activities of daily living (ADL), and quality of life (QoL), and the University of California, Los Angeles (UCLA) activity score. Kendall’s tau were calculated for correlation analyses.Results: In total, 145 patients (28 male, 117 female) were included. The PROMs improved significantly across males and females at the latest follow-up. Female patients had significantly lower preoperative PROMs: mHHS (47 vs 57.4; p = 0.002); HOOS pain (44.9 vs 60; p = 0.003), sport (47 vs 57.4; p = 0.002), ADL (58.9 vs 69.3; p = 0.032), and QoL (26.8 vs 39.3; p = 0.009); and UCLA (5.6 vs 6.7, p = 0.042) scores. Males showed higher postoperative UCLA scores (7.5 vs 6.7; p = 0.03). Kendall’s tau showed significant negative correlation between BMI and UCLA scores in females and males (-0.21 to -0.29; p = 0.002/0.048), while BMI and HOOS sport (-0.16; p = 0.015) and ADL (-0.2; p = 0.003), as well as QoL (-0.14; p = 0.031) and preoperative acetabular inclination (-0.13; p = 0.049) were only significantly negatively correlated in females.Conclusion: Patient sex affects PROMs before and after PAO. Female patients experience higher improvement in hip function and activity level, due to poorer preoperative PROMs than males. Thus, these data are particularly interesting in providing preoperative guidance regarding postoperative outcome expectations.Cite this article: Bone Jt Open 2024;6(1):35–42.

Background/Objectives: This study evaluated the learning curve for robotic-assisted total knee arthroplasty (RA TKA) performed by three experienced surgeons, focusing on procedure duration, surgeon satisfaction, and confidence. Methods: A prospective study was conducted with three senior arthroplasty surgeons, each performing 15 RA TKA procedures using the Triathlon Knee System with the Robotic Arm Interactive Orthopedic (RIO) System. Data on preparation, cut-to-suture, and breakdown times were collected. Surgeon anxiety levels were measured preoperatively using the STAI-6 scale, while postoperative satisfaction and confidence were assessed via a questionnaire. Statistical analysis was conducted using GraphPad Prism. Results: Of 50 scheduled surgeries, 45 were completed. The average cut-to-suture time was 1 h 38 min, with significant time reductions in robotic-specific steps as experience increased. Comparing the first five surgeries to the last five, the time for navigation hardware mounting, landmarks registration, femur and tibia registration, and bone preparation decreased by up to 30% (p < 0.001 to p = 0.025). General instrument preparation time decreased by 20% (p = 0.004). Surgeon anxiety levels dropped, indicating increased comfort with the system, while postoperative surveys showed increased satisfaction and confidence. Conclusions: The study demonstrated a substantial learning curve for RA TKA, with improved efficiency and surgeon confidence by the fifteenth procedure. These findings highlight the potential for streamlined workflows and guide training for new adopters of robotic knee arthroplasty.

Chondrosarcoma (CS) is a rare malignant bone sarcoma that primarily affects cartilage cells in the femur and pelvis. While most subtypes exhibit slow growth with a very good prognosis, some aggressive subtypes have a poorer overall survival. CS is known for its resistance to chemotherapy and radiotherapy, leaving surgery as the sole effective therapeutic option. Cold physical plasma (CPP) has been explored in vitro as a potential therapy, demonstrating positive anti-tumor effects on CS cells. This study investigated the synergistic effects of combining CPP with cytostatics on CS cells. The chemotherapeutic agents cisplatin, doxorubicin, and vincristine were applied to two CS cell lines (CAL-78 and SW1353). After determining their IC₂₀ and IC₅₀, they were combined with CPP in both cell lines to assess their impact on the cell proliferation, viability, metabolism, and apoptosis. This combined approach significantly reduced the cell proliferation and viability while increasing the apoptosis signals compared to cytostatic therapy alone. The combination of CPP and chemotherapeutic drugs shows promise in targeting chemoresistant CS cells, potentially improving the prognosis for patients in clinical settings.

Shoulder pain is a common issue often linked to conditions such as subacromial impingement or rotator cuff lesions. The role of the acromion in these symptoms remains a subject of debate. This study aims to establish standardized values for commonly used acromion dimensions based on whole-body MRI scans of a large and healthy population and to investigate potential correlations between acromion shape and influencing factors such as sex, age, BMI, dominant hand, and shoulder pain. The study used whole-body MRI scans from the Study of Health in Pomerania, a German population-based study. Acromion index, acromion tilt, and acromion slope were measured. Interrater variability was tested with two independent, trained viewers on 100 MRI sequences before actual measurements started. Descriptive statistics and logistic regression were used to evaluate the results. We could define reference values based on a shoulder-healthy population for each acromion parameter within the 2.5 to 97.5 percentile. No significant differences were found in acromion slope, tilt, and index between male and female participants. No significant correlations were observed between acromion morphology and anthropometric parameters such as height, weight, or BMI. No significant differences were observed in acromion parameters between dominant and non-dominant hands or stated pain intensity. This study provides valuable reference values for acromion-related parameters, offering insight into the anatomy of a healthy shoulder. The findings indicate no significant differences in acromion morphology based on sex, weight, BMI, or dominant hand. Further research is necessary to ascertain the clinical implications of these reference values. The establishment of standardized reference values opens new possibilities for enhancing clinical decision making regarding surgical interventions, such as acromioplasty.

Background: Bone marrow-derived mesenchymal stromal cells (BM-MSCs) are used in regenerative medicine and related research involving immunomodulatory, anti-inflammatory, anti-fibrotic and regenerative functions. Isolation of BM-MSCs from samples obtained during total hip arthroplasty (THA) is routinely possible. Advanced age and comorbidities of the majority of patients undergoing THA limit their applicability. Our study aimed to evaluate the potential of bone marrow obtained during periacetabular osteotomy (PAO) as a novel source of BM-MSCs from young donors by analyzing cell yield and cell characteristics. Methods: Bone samples were obtained from the anterior Os ilium or superior Os pubis during PAO and from the femoral cavity during primary THA. Isolation of bone marrow-derived mononuclear cells (BM-MNCs) was performed by density gradient centrifugation. The samples from PAO and THA patients were compared in terms of BM-MSC yield, colony formation and the proportion of BM-MSCs within the BM-MNC population using flow cytometry analysis. The cells were characterized based on the expression of BM-MSC-specific surface markers. The functionality of the cells was compared by quantifying post-thaw viability, metabolic activity, proliferation capacity, senescence-associated beta galactosidase (SA-β-gal) expression, trilineage differentiation potential and major secretome proteins. Results: Isolation of BM-MNCs was possible in a reliable and reproducible manner when using bone from PAO containing more than 0.24 g bone marrow. PAO patients were younger than patients of the THA group. Bone obtained during PAO contained less bone marrow and led to a lower BM-MSC number after the first cell culture passage compared to BM-MSCs obtained during THA. BM-MSCs from PAO samples are characterized by a higher proliferation capacity. This results in a higher yield in cell culture passage two, when normalized to the sample weight. BM-MSCs from PAO patients showed increased secretion of TGF-β1, TIMP2, and VEGF upon osteogenic differentiation. BM-MSCs from PAO and THA patients revealed similar results regarding the onset of SA-β-gal expression and trilineage differentiation capacity. Conclusions: We suggest that bone obtained during PAO is a promising novel source for BM-MSCs from young donors. Limited absolute cell yield due to low sample weight must be considered in early cell culture passages and might be critical for the range of clinical applications possible for BM-MSCs from this source. The higher proliferation capacity and increased growth factor secretion of BM-MSCs from young donors may be beneficial for future regenerative cell therapies, in vitro models, and tissue engineering.

Psychologic comorbidities have been identified as risk factors for poor outcomes in orthopedic procedures, but their influence on the outcome of hip-preserving periacetabular osteotomy (PAO) remains uncertain. This retrospective cohort study aimed to assess the impact of patients’ psychological health on the outcome of PAO in patients with hip dysplasia (HD) and acetabular retroversion (AR). The study included 110 patients undergoing PAO for HD or AR between 2019 and 2021. Standardized questionnaires were administered to assess psychological factors, postoperative hip function, and activity level (mean follow-up: 25 months). Linear regression analyses were used to examine the associations between psychological factors and postoperative hip function and activity level. Both HD and AR patients showed improved postoperative hip function and activity levels. Linear regression analyses revealed that depression significantly impaired postoperative outcomes in both groups, whereas somatization negatively influenced the outcome in AR patients. General health perceptions significantly contributed to an improved postoperative outcome. These findings highlight the importance of concomitantly addressing psychologically relevant factors in order to improve patient outcomes after PAO procedures. Future prospective studies should continue to investigate the impact of various psychological factors and explore possibilities of incorporating psychological support into routine postoperative care for these patient cohorts.