Increased Humeral Retrotorsion is not a Risk Factor for Overuse Injury of the Throwing Shoulder in Elite Youth Handball Athletes.

PURPOSE: To identify the potential role of humeral retrotorsion (HRT) and range of motion (ROM) as a risk factor for shoulder overuse injury in elite youth handball players. The hypothesis was that increased HRT is associated with an increased risk of shoulder overuse injury. METHODS: Over two seasons, 258 elite youth handball players (52% boys; age:14±0.8years) were included. Pre-season assessment included HRT and glenohumeral internal (IR) and external (ER) rotational ROM using ultrasound and a manual goniometer. Sports-specific adaptations between male and female athletes and the dominant and nondominant shoulder were calculated. In addition, players completed standardized questionnaires over the 2018-2019 or 2019-20 season and reported any shoulder overuse symptoms using the Western Ontario Shoulder Index questionnaire. RESULTS: Comparing male and female players showed significantly decreased HRT and decreased internal ROM in the dominant side of male athletes (p≤0.027). No other difference was found. Significant side-to-side differences between the dominant and non-dominant shoulder were found for HRT, IR, and ER, regardless of sex (p<0.001). For total range of motion (TROM), only female athletes showed a significant increase in the dominant arm (p=0.032). The dominant side showed a significantly higher glenohumeral internal rotation deficit (GIRD) in male athletes than in female athletes (10°±17° vs. 5°±10°, p=0.011). Adaptations in HRT, ER gain, and TROM gain were not significant. Over the course of the two seasons, 20 athletes reported shoulder overuse injuries. Although GIRD was borderline non-significant (p=0.056), none of the parameters tested were significantly associated with shoulder overuse injuries. CONCLUSION: Despite significant side-to-side differences and sport-specific adaptations, individual pre-season screening of humeral retrotorsion and soft tissue adaptations does not identify elite youth handball athletes at increased risk of shoulder overuse injury.

A Narrative Review of the Roles of Chondromodulin-I (Cnmd) in Adult Cartilage Tissue.

Articular cartilage is crucial for joint function but its avascularity limits intrinsic repair, leading to conditions like osteoarthritis (OA). Chondromodulin-I (Cnmd) has emerged as a key molecule in cartilage biology, with potential implications for OA therapy. Cnmd is primarily expressed in cartilage and plays an important role in chondrocyte proliferation, cartilage homeostasis, and the blocking of angiogenesis. In vivo and in vitro studies on Cnmd, also suggest an involvement in bone repair and in delaying OA progression. Its downregulation correlates with OA severity, indicating its potential as a therapeutic target. Further research is needed to fully understand the mode of action of Cnmd and its beneficial implications for managing OA. This comprehensive review aims to elucidate the molecular characteristics of Cnmd, from its expression pattern, role in cartilage maintenance, callus formation during bone repair and association with OA.

Total blood loss and early clinical outcomes under different tranexamic acid regimes in total knee arthroplasty.

BACKGROUND: Many different regimes of intravenous and local tranexamic acid (TXA) reduce total blood loss (TBL) in patients undergoing total knee arthroplasty (TKA). However, the most effective TXA regime in reducing blood loss might not be most beneficial for the patient. The aim of the present study was to investigate the effect of commonly used TXA regimes on blood loss and on early clinical outcomes. METHODS: We performed this monocentric retrospective study in patients undergoing primary TKA. Primary outcome was the estimated TBL. Secondary outcomes were the rates of adverse events (AE) as well as the range of motion (ROM), mobility and pain intensity during the first three physiotherapy sessions (PTS). RESULTS: We analysed the data of 1250 TKAs. 5 different TXA regimes were applied. TBL (mean ± SE) was 953 ± 64 ml (2xiv), 999 ± 19 ml (2xiv + 1xlocal), 1075 ± 19 ml (1xiv + 1xlocal), 1191 ± 39 ml (1xlocal) and 1241 ± 48 ml (1xiv) (p < 0.01). In the linear regression model for TBL a lower number of TXA applications was a predictor for increased blood loss (p < 0.01). AE rates were lowest under 2xiv (0%) and 2xiv + 1xlocal (4.8%). Highest mobility and lowest pain intensity were observed under 1x iv and 2x iv. The largest portions of fully mobile patients on day three were observed under 1xiv (100%), 2xiv (100%) and 2xiv + 1local TXA (86.9%). CONCLUSION: Our results suggest that multiple applications of TXA are more effective in decreasing blood loss than excessive dosing of TXA. Interestingly, local use of TXA might be associated with higher pain intensity and decreased mobility on the first days after surgery.

Trends in Shoulder Arthroplasty in Germany: A 10-Year Epidemiological Analysis of Patients with Primary Osteoarthritis of the Shoulder.

Shoulder arthroplasty has significantly gained popularity in orthopedic surgery, driven by progress in prosthesis design and surgical techniques. This study explored the epidemiology of shoulder arthroplasty, analyzing healthcare data from 2012 to 2022 for primary osteoarthritis of the shoulder. The data included patient demographics and types of surgical procedures. Data analysis indicates a higher utilization rate of reverse total shoulder arthroplasty (RTSA; n = 41,251) over total- (TSA; n = 18,679) and hemiarthroplasty (HSA; n = 12,827) for primary shoulder osteoarthritis. Overall, a significant increase in RTSA procedures from n = 2237 (2012) to n = 5415 (2022) was observed, representing more than a two-fold increase of 121.1%. The relative proportion of RTSA among all types of shoulder arthroplasty increased from 39% (2012) to 68.6% (2022), while HSA decreased and TSA essentially remained constant. Age analysis identified the following peaks: RTSA, 77 ± 7 y; HSA, 68 ± 12 y; and TSA, 67 ± 10 y. Among the over 60s, significantly more women were treated with any type of prosthesis, whereas in young patients (45 to 59 y), more men received HSA or TSA. Our study confirms that RTSA has become the preferred choice for elderly patients in Germany, reflecting the prevailing preference despite varying patient ages and conditions, with a noted difference in sex in treatment prevalence.

Modeling Myeloma Dissemination In Vitro with hMSC-interacting Subpopulations of INA-6 Cells and Their Aggregation/Detachment Dynamics.

Multiple myeloma involves early dissemination of malignant plasma cells across the bone marrow; however, the initial steps of dissemination remain unclear. Human bone marrow-derived mesenchymal stromal cells (hMSC) stimulate myeloma cell expansion (e.g., IL6) and simultaneously retain myeloma cells via chemokines (e.g., CXCL12) and adhesion factors. Hence, we hypothesized that the imbalance between cell division and retention drives dissemination. We present an in vitro model using primary hMSCs cocultured with INA-6 myeloma cells. Time-lapse microscopy revealed proliferation and attachment/detachment dynamics. Separation techniques (V-well adhesion assay and well plate sandwich centrifugation) were established to isolate MSC-interacting myeloma subpopulations that were characterized by RNA sequencing, cell viability, and apoptosis. Results were correlated with gene expression data (n = 837) and survival of patients with myeloma (n = 536). On dispersed hMSCs, INA-6 saturate hMSC surface before proliferating into large homotypic aggregates, from which single cells detached completely. On confluent hMSCs, aggregates were replaced by strong heterotypic hMSC-INA-6 interactions, which modulated apoptosis time dependently. Only INA-6 daughter cells (nMA-INA6) detached from hMSCs by cell division but sustained adherence to hMSC-adhering mother cells (MA-INA6). Isolated nMA-INA6 indicated hMSC autonomy through superior viability after IL6 withdrawal and upregulation of proliferation-related genes. MA-INA6 upregulated adhesion and retention factors (CXCL12), that, intriguingly, were highly expressed in myeloma samples from patients with longer overall and progression-free survival, but their expression decreased in relapsed myeloma samples. Altogether, in vitro dissemination of INA-6 is driven by detaching daughter cells after a cycle of hMSC-(re)attachment and proliferation, involving adhesion factors that represent a bone marrow-retentive phenotype with potential clinical relevance. SIGNIFICANCE: Novel methods describe in vitro dissemination of myeloma cells as detachment of daughter cells after cell division. Myeloma adhesion genes were identified that counteract in vitro detachment with potential clinical relevance.

[Individualized surgical treatment of sarcomas of the extremities]. / Chirurgische Therapieindividualisierung bei Sarkomen der Extremitäten.

Sarcomas of the extremities are rare entities, the treatment of which requires special expertise. Even if the treatment of patients is always interdisciplinary, the surgical R0 resection is the key point of each curatively intended treatment. In addition to resection in sano, the aim is to preserve the extremities and function, so that defect reconstruction after resection plays a decisive role. Due to the heterogeneity of tumors as well as their localization and extent, reconstruction is always an individually adapted treatment. Modular tumor endoprostheses are often used in this context, which can be constructed according to the size of the defect. The transplantation of autologous or allogeneic bone is also frequently used alone or as an additive procedure. Patient-specific (mega)prostheses are used particularly for pelvic tumors. Defect reconstruction using scaffold-based procedures from the field of tissue engineering is being tested as a promising procedure for the future. This article provides an overview of the treatment principles for sarcomas of the extremities and their individual reconstruction options.

Zirconium as a Promising Synovial Biomarker for Loose Cemented Knee Prosthesis.

BACKGROUND: Aseptic loosening is the most common mode of failure after total knee arthroplasty. Despite this, the diagnosis often remains challenging and mainly relies on imaging modalities. Until today, no biomarker exists to aid in diagnosing loosening of the implants. As zirconium (Zr) is often found in bone cement, where it serves as radiopacifier, this study aimed to establish Zr as a synovial biomarker for loosened cemented knee prostheses. METHODS: A total of 31 patients scheduled for revision of a cemented knee prostheses were included. In all patients, the initial used cement contained Zr. After arthrotomy, specimens of synovial fluid were taken and levels of Zr were measured by inductively coupled plasma mass spectrometry. Depending on the necessary amount of force for explantation, the implants were graded "loose" or "well-fixed". Preoperative radiographs were evaluated by 2 independent physicians. RESULTS: The concentration of Zr in the synovial fluid differed significantly (P < .001) between the "loose" (mean 170.9 µg/L, range 0 to 1941 µg/L) and the "well-fixed" (mean 0.6 µg/L, range 0 to 6 µg/L) implants. The receiver operating characteristic analysis revealed 0.25 µg/l as an optimal cutoff value leading to a sensitivity of 0.84, a specificity of 0.92, a positive predictive value of 0.94, and a negative predictive value of 0.79. There was no significant difference in the diagnostic performance compared to radiographs (P = .66). CONCLUSIONS: Zirconium proved to be a reliable novel synovial biomarker for diagnosing aseptic loosening of knee prothesis fixed with cement containing Zr. This biomarker should not be interpreted in isolation, but in combination with existing diagnostic tools.

Orthopaedics and Trauma Surgery in Germany in 2023 - Will We Have Sufficient Doctors in the Future? / Orthopädie und Unfallchirurgie 2023 ­ haben wir genug Nachwuchs?

There has been a growing shortage of physicians in Germany in recent years. In this study, we analyse the situation facing orthopaedic hospitals and trauma centres.Between 22 November and 5 December 2022, a web-based questionnaire was sent out by the Academy of the German Trauma Society (AUC) and by the Society of Leading Orthopaedic and Trauma Surgeons (VLOU).The questionnaire was answered by 185 heads of department. Of the responses, 20% came from university hospitals or major trauma centres, and a third from regional or local clinics. More than half of the hospital departments (55%) had a median of 2.7 vacant doctor positions. Among those hospitals, 47% had a vacant position for a consultant, 33% for a board-certified specialist, and 89% for a junior doctor. Within the university hospitals, only one third had vacant doctor positions. The responding heads of department gave negative feedback regarding the number of applications, the qualifications of young doctors, and their motivation for scientific work (in university hospitals).More than half of the responding hospitals had vacant doctor positions. If we are to counteract the growing shortage of doctors in orthopaedics and trauma surgery, the number of clinical doctors in general and the working conditions in hospitals have to be improved. Teaching hospitals should try to improve the training of medical students with a view to inspiring greater motivation to work in orthopaedics and trauma surgery.

Current Trends in Orthopaedics and Trauma in Germany.

During the Guest Nation Symposium (cobranded with the Deutsche Gesellschaft für Orthopädie und Unfallchirurgie, Deutsche Gesellschaft für Orthopädie und Orthopädische Chirurgie, and Deutsche Gesellschaft für Unfallchirurgie) at the 2023 American Academy of Orthopaedic Surgeons Congress in Las Vegas, the goal was to compile nationally important content from German orthopaedics and trauma surgery. This resulted in a mix of content on the latest developments in trauma care, knee arthroplasty, spinopelvic importance for hip arthroplasty, stemless shoulder endoprostheses, joint preservation for ankle osteoarthritis, trauma education, and research. Of course, this is only a small selection of the important issues that are being driven forward in Germany.

Impaired FADD/BID signaling mediates cross-resistance to immunotherapy in Multiple Myeloma.

The treatment landscape in multiple myeloma (MM) is shifting from genotoxic drugs to immunotherapies. Monoclonal antibodies, immunoconjugates, T-cell engaging antibodies and CART cells have been incorporated into routine treatment algorithms, resulting in improved response rates. Nevertheless, patients continue to relapse and the underlying mechanisms of resistance remain poorly understood. While Impaired death receptor signaling has been reported to mediate resistance to CART in acute lymphoblastic leukemia, this mechanism yet remains to be elucidated in context of novel immunotherapies for MM. Here, we describe impaired death receptor signaling as a novel mechanism of resistance to T-cell mediated immunotherapies in MM. This resistance seems exclusive to novel immunotherapies while sensitivity to conventional anti-tumor therapies being preserved in vitro. As a proof of concept, we present a confirmatory clinical case indicating that the FADD/BID axis is required for meaningful responses to novel immunotherapies thus we report impaired death receptor signaling as a novel resistance mechanism to T-cell mediated immunotherapy in MM.

Setting the distal and posterior condyle of the femoral component to restore the medial pre-arthritic femoral articular surface results in better outcomes after total knee arthroplasty.

PURPOSE: The present study of total knee arthroplasty (TKA) describes an intra-operative method that determines the direction and quantifies the magnitude of deviation of the distal and the posterior medial and lateral (DM, PM, DL, and PL) condyle of the femoral component relative to the pre-arthritic femoral articular surface. For each femoral condyle, the deviations were categorized, and an analysis determined which had better or worse Forgotten Joint Score (FJS), Oxford Knee Score (OKS), and WOMAC scores at 1-year follow-up. METHODS: Four academic arthroplasty surgeons supervised a cemented primary CR TKA (Triathlon, Stryker) on 120 consecutive patients. 103 that completed patient-reported outcome measures (PROMs) were analyzed. The surgeon determined the direction and the magnitude of deviation of the condyle of the femoral component by intraoperatively measuring the thickness of the femoral resection, adding compensations of 1 mm for the saw kerf and 2 mm for worn cartilage, and then subtracting the thickness of the femoral component's condyle. For each femoral condyle, a Kruskal-Wallis test determined the categories of deviation with clinically important and significantly different 1-year PROMs. RESULTS: A 1 to 2.5 mm and 3 mm or more proximal deviation of the DM condyle of the femoral component worsened the median FJS by 35 and 40 points, OKS by 9 and 14 points, and WOMAC score by 9 and 17 points, respectively, relative to those with a -0.5 to 0.5 mm deviation (p < 0.01). A 1 to 2.5 mm and 3 mm or more anterior deviation of the PM condyle of the femoral component worsened the FJS by 34 and 48 points, OKS by 7 and 13 points, and WOMAC scores by 8 and 16 points, respectively (p < 0.01). Deviations of the DL and PL condyle of the femoral component did not affect PROMs (p ≥ 0.13). CONCLUSIONS: Although many factors can affect PROM, such as patient expectations, the surgeon should understand that setting the DM and the PM condyles of the femoral component within 1 mm of the patient's pre-arthritic femoral articular surface can potentially result in better FJS, OKS, and WOMAC scores at 1 year. LEVEL OF EVIDENCE: II, Prospective cohort study.

The AMADEUS score is not a sufficient predictor for functional outcome after autologous chondrocyte implantation (ACI) of the knee: data from the German Cartilage Registry (KnorpelRegister DGOU).

INTRODUCTION: The AMADEUS (Area Measurement And DEpth and Underlying Structures) score has advanced to a commonly used tool for MRI-based chondral defect severity grading prior to cartilage knee surgery. It was the intention of this study to assess the AMADEUS for a potential correlation with clinical data by patient-reported outcome measures (PROMs). METHODS: A total of 51 patients undergoing ACI (autologous chondrocyte implantation) between 2016 and 2022 were found eligible and retrospectively analyzed. All patients were registered in the German Cartilage Registry prior to surgery and follow-up data were collected using the Knee Osteoarthritis Outcome score (KOOS), the International Knee Documentation Committee (IKDC) Form and the numeric rating scale (NRS). Pre-operative MRI images were scored by three raters using the AMADEUS classification system, and an overall AMADEUS score was calculated which was subsequently correlated with pre- and post-operative PROMs. RESULTS: Mean patient age was 32.67 ± 8.37 years and mean defect size area 343.04 mm2 ± 139.45 mm2. No correlative capacity of the pre- and postoperative IKDC, KOOS or NRS scores was found with the AMADEUS final score or any of its subscores. From the pre- to postoperative visit, a significant improvement of the PROMs (IKDC: 45.53 ± 21.00 vs. 59.83 ± 17.93, p = 0.04; KOOS Pain: 58.00 ± 16.70 vs. 76.06 ± 19.20, p = 0.03; KOOS ADL: 64.17 ± 18.76 vs. 82.11 ± 16.68, p < 0.01; KOOS Sports: 26.11 ± 18.52 vs. 50.56 ± 23.94, p = 0.01; KOOS QOL: 25.50 ± 14.26 ± 45.28 ± 19.03, p = 0.00) was found. Intraclass correlation coefficients showed an overall good interrater agreement for the AMADEUS total score (ICC = 0.75). CONCLUSIONS: Study results suggest no correlative capacity of the AMADEUS with routinely used PROMs in patients undergoing ACI. Therefore, radiographically assessed cartilage defect characteristics poorly translate to pre- and postoperative patient-reported outcome data.

Epidemiology and Trends in Cartilage Surgery of the Foot and Ankle in Germany: An Analysis of National Healthcare Billing and Reporting Data from 2006 to 2020.

Background and objectives: Cartilage surgery constitutes a standard intervention in foot and ankle procedures. Currently, there is a lack of epidemiological data on its frequency, age distribution, and surgical options for cartilage surgery. This study aimed to investigate the current landscape of cartilage surgery in Germany and identify the most common procedures from an epidemiological standpoint. Materials and methods: Medical billing and reporting data from the Federal Statistical Office of Germany, encompassing the period 2006-2020, was examined, including all foot and ankle cartilage surgical procedures (summarized under OPS codes 5-812 and 5-801). The dataset incorporated information on the affected joint, patient age and sex, and surgery type. Each surgical procedure was categorized as "debridement", "regeneration" or "refixation". Linear and nonlinear regression analyses were employed, with a statistical significance threshold of 0.05. Results: From the total of 136,501 procedures conducted during the study period, the most frequently performed interventions were microfracture (58,252) and chondroplasty (56,135), and thus, debridement procedures were in the leading position. The use of acellular membranes was the most used regenerative technique (n = 11,414). At the ankle joint, interventions were mostly arthroscopic and in men, while foot cartilage surgeries were preferably performed via open surgery and mostly in women. Age distribution analysis revealed two primary peaks: the first in the 20-25-year-old group (ankle and foot) and the second in the 45-50-year-old group (ankle) and 55-60-year-old group (foot). Refixation and regenerative procedures were more frequent among younger individuals, while debriding procedures were more frequent among older individuals. Regenerative procedures, particularly in the ankle, significantly increased over time. Conclusions: Cartilage surgery of the foot and ankle was common, with two primary age groups predominantly affected. Notably, recent years have witnessed a considerable rise in cartilage regenerative procedures.

Patient-specific articulating spacer for two-stage shoulder arthroplasty exchange.

OBJECTIVE: Two-stage exchange with an antibiotic-loaded polymethylmethacrylate (PMMA) spacer is standard treatment for chronic periprosthetic joint infection of the shoulder. We present a safe and simple technique for patient-specific spacer implants. INDICATION: (Chronic) periprosthetic joint infection of the shoulder. RELATIVE CONTRAINDICATIONS: Known allergy against components of PMMA bone cements. Inadequate compliance for two-stage exchange. Patient is unfit to undergo two-stage exchange. SURGICAL TECHNIQUE: Hardware removal, histologic and microbiologic samples, and debridement. Preparation of targeted or calculated antibiotic-loaded PMMA. Tailoring of patient-specific spacer. Spacer implantation. POSTOPERATIVE MANAGEMENT: Rehabilitation protocol. Antibiotic treatment. Reimplantation after successful eradication of infection.

Handmade articulating spacer for two-stage exchange at the knee.

OBJECTIVE: Two-stage exchange with implantation of a temporary spacer is considered gold standard treatment for chronic periprosthetic joint infection of the knee. This article describes a simple and safe technique for handmade articulating spacers at the knee. INDICATION: Chronic or relapsing periprosthetic joint infection of the knee. RELATIVE CONTRAINDICATIONS: Known allergy against components of polymethylmethacrylate (PMMA) bone cements or admixed antibiotics. Inadequate compliance for two-stage exchange. Patient not able to undergo two-stage exchange. Bony defect situation at the tibia or femur leading to collateral ligament insufficiency. Soft tissue damage with need for plastic temporary vacuum-assisted wound closure (VAC) therapy. SURGICAL TECHNIQUE: Removal of the prosthesis, thorough debridement of necrotic and granulation tissue, tailoring bone cement with antibiotics. Preparation of a tibial and femoral stem. Customizing the tibial and femoral articulating spacer components to bony anatomy and soft tissue tension. Confirmation of correct position by intraoperative radiography. POSTOPERATIVE MANAGEMENT: Protection of the spacer with an external brace. Restricted weight-bearing. Passive range of motion as possible. Intravenous-followed by oral antibiotics. Reimplantation after successful treatment of infection.

Handmade spacers for two-stage exchange at the hip.

OBJECTIVE: Two-stage exchange with implantation of a temporary spacer is the gold standard treatment for chronic periprosthetic joint infection of the hip. This article describes a simple and safe technique for handmade spacers at the hip. INDICATION: Periprosthetic joint infection of the hip. Septic arthritis of the native joint. CONTRAINDICATIONS: Known allergy against components of polymethylmethacrylate bone cements. Inadequate compliance for two-stage exchange. Patient unfit to undergo two-stage exchange. Bony defect situation at the acetabulum impeding stable reduction of the spacer. Bone loss at the femur jeopardizing stable fixation of the stem. Soft tissue damage with need for plastic temporary vacuum-assisted wound closure (VAC) therapy. SURGICAL TECHNIQUE: Tailoring bone cement with antibiotics. Preparation of a metal endoskeleton. Molding of spacer stem and head by hand. Customizing spacer off-sets to bony anatomy and soft tissue tension. Implantation assuring rotational stability at the femur with a bone cement collar. Confirmation of correct position by intraoperative radiography. POSTOPERATIVE MANAGEMENT: Restricted weight-bearing. Range of motion as possible. Reimplantation after successful treatment of infection.

Does radiolucency really predict loose components in revision shoulder arthroplasty?

OBJECTIVE: The number of shoulder arthroplasties is increasing along with the need for revision surgeries. Determining the stability of the implant is crucial in preoperative planning. This study aims to investigate whether radiolucent lines (RLL) in preoperative radiographs predict component loosening. MATERIALS AND METHODS: Preoperative radiographs of 93 cases in 88 patients who underwent shoulder arthroplasty revision were evaluated regarding the presence of RLL. Correlation analyses were performed for radiographic findings and demographic factors (age, gender, BMI, prior surgeries) compared to intraoperative findings. RESULTS: The presence of RLL around the humeral component correlated with loosening (p < 0.001, Phi 0.511), and the distal zones 3 and 5 showed the strongest correlation (Phi 0.536). While RLL in only one zone did not predict loosening (p = 0.337), RLL present in two or more zones showed correlation with loosening (p < 0.001). Risk factors associated with loosening were a higher age at the time of revision surgery (p = 0.030) and the number of zones with RLL (p < 0.001). The glenoid component was loose in 39.0% of the cases; 5.5% of the glenoid components with RLL were stable. Nevertheless, the presence of RLL was highly associated with loosening (p < 0.001, Phi 0.603). A longer time between implantation and revision correlated with loosening of the glenoid component (p = 0.046). CONCLUSION: While RLL do not predict loosening of the implant in general, occurrence in more than one zone correlates with loosening. If located in distal zones and with increasing number of zones with RLL, the correlation becomes even stronger and loosening is more likely.

Efficacy of post-operative partial weight-bearing after total knee arthroplasty - a prospective observational trial.

PURPOSE: There is little evidence proving the concept of partial weight-bearing to be efficient and feasible. Using insole pressure measurement systems, this study aimed to explore the compliance to prescribed weight-bearing restrictions after total knee arthroplasty (TKA). METHODS: 50 patients after TKA were recruited in a prospective manner. They were advised to limit weight-bearing of the affected limb to 200 N. True load was measured via insole force-sensors on day one after surgery (M1) and before discharge (M2). Compliance to the rehabilitation protocol was the primary outcome parameter. RESULTS: At M1 and M2 compliance to the rehabilitation protocol was 0% und 2%, respectively. 84% (M1) and 90% (M2) of patients overloaded the affected limb during every step. The affected limb was loaded with 50% ± 14% (M1) and 57% ± 17% (M2) of body weight. Patients older than 65 loaded the affected limb on average 17% (M1) and 34% (M2) more than their younger counterparts did. This difference was even more pronounced when walking stairs up (49% increase on average) and down (53% increase on average). CONCLUSION: Surgeons must take into consideration that the ability to maintain partial weight-bearing after TKA is highly dependent on the age of the patient and the achievable load reduction is determined by the patient's body weight.

Demographics and Etiology for Lower Extremity Amputations-Experiences of an University Orthopaedic Center in Germany.

Background and Objectives: Currently, the worldwide incidence of major amputations in the general population is decreasing whereas the incidence of minor amputations is increasing. The purpose of our study was to analyze whether this trend is reflected among orthopaedic patients treated with lower extremity amputation in our orthopaedic university institution. Materials and Methods: We conducted a single-center retrospective study and included patients referred to our orthopaedic department for lower extremity amputation (LEA) between January 2007 and December 2019. Acquired data were the year of amputation, age, sex, level of amputation and cause of amputation. T test and Chi² test were performed to compare age and amputation rates between males and females; significance was defined as p < 0.05. Linear regression and multivariate logistic regression models were used to test time trends and to calculate probabilities for LEA. Results: A total of 114 amputations of the lower extremity were performed, of which 60.5% were major amputations. The number of major amputations increased over time with a rate of 0.6 amputation/year. Men were significantly more often affected by LEA than women. Age of LEA for men was significantly below the age of LEA for women (men: 54.8 ± 2.8 years, women: 64.9 ± 3.2 years, p = 0.021). Main causes leading to LEA were tumors (28.9%) and implant-associated complications (25.4%). Implant-associated complications and age raised the probability for major amputation, whereas malformation, angiopathies and infections were more likely to cause a minor amputation. Conclusions: Among patients in our orthopaedic institution, etiology of amputations of the lower extremity is multifactorial and differs from other surgical specialties. The number of major amputations has increased continuously over the past years. Age and sex, as well as diagnosis, influence the type and level of amputation.