Search Results (190)

Background/Objectives: One-stage revision has become an increasingly accepted strategy for the treatment of chronic periprosthetic joint infection (PJI) of the knee in carefully selected patients. The use of a resorbable defensive antibacterial coating (DAC^® hydrogel) represents an attractive adjunct to reduce bacterial adhesion and biofilm formation on revision implants. However, evidence regarding its long-term performance is limited. Methods: We retrospectively reviewed 52 consecutive patients undergoing one-stage revision for knee PJI or an infected spacer between 2014 and 2023 using a standardized surgical and antimicrobial protocol including local application of DAC hydrogel loaded with vancomycin alone or vancomycin plus meropenem. Clinical, microbiological, and radiographic outcomes were evaluated. Infection-free survival was assessed using Kaplan–Meier analysis. Results: Forty-eight patients underwent revision for PJI and four for septic spacers. Four patients were unavailable for final evaluation. At follow-up of 7.7 ± 2.9 years (range 2.5–12.2 years), 47 of 48 clinically evaluable patients remained infection-free, corresponding to a crude infection-free proportion of 97.9%. Kaplan–Meier infection-free survivorship at 12 years was 98.1% (95% CI, 87.1–99.7%). Mean Knee Society Score improved from 47.7 to 84.4 points, while functional KSS improved from 41.9 to 82.9 points. Pain at rest decreased from 6.9 to 0.7 and pain during movement from 8.1 to 1.6 on the visual analogue scale. Conclusions: This series represents, to our knowledge, the longest reported follow-up of one-stage knee revision using the DAC hydrogel coating. The favorable outcomes observed with this hybrid fixation strategy support further investigation of this approach in larger, long-term, comparative multicenter studies. Full article

Background/Objectives: Studies consistently demonstrate that microprocessor-controlled prosthetic knees (MPKs) improve mobility and quality of life for people with lower limb loss or absence by enhancing balance and reducing falls. However, the extent to which these benefits apply across demographic groups remains unclear. Therefore, we conducted a literature review to evaluate how representative and transferable research on MPKs is across different populations, and which factors influence this. Methods: Using systematic review principles and PRISMA guidelines, 27 studies were analysed from databases including Cochrane, CINAHL, MEDLINE, and PubMed, as of 20th September 2025. The included studies primarily focused on young-to-middle-aged adults, men, individuals with trauma-related amputation, and higher mobility levels. Results: We found that older adults, women, and individuals with amputation caused by vascular disease or diabetes were under-represented in MPK research. Moreover, variability in time since amputation complicates the generalisability of findings, as this factor significantly influences adaptation and functional outcomes. Conclusions: While evidence supports MPKs’ effectiveness in enhancing mobility and reducing the risk of falls, their benefits may not fully apply to under-represented groups, such as older adults, women, or low-activity users. Future research should prioritise more diverse participant samples to improve the generalisation of MPK outcomes across different demographics and functional levels. Full article

Background/Objectives: Lower-limb amputation significantly impacts autonomy and daily functioning. Microprocessor-controlled prosthetic knees (MPKs) improve mobility, safety, and quality of life compared with non-microprocessor prosthetic knees (nMPKs). Despite general benefits, differences among MPK models remain unclear. The goal of this investigation was to evaluate functional mobility and patient-reported outcomes in active transfemoral amputees using a new MPK (PROTEOR QUATTRO) compared with existing MPKs. Methods: In this multicenter cross-over clinical trial, active transfemoral amputees were assessed using patient-specific functional scales (PSFS), standardized locomotor capacity tests (6MWT, 10mWT, HAI, SAI) and satisfaction and quality-of-life questionnaires (PEQ-A, SF-36, ESAT). Biomechanical data collection was performed during walking test, to examine gait symmetry indices. Results: The QUATTRO MPK was associated with significantly higher PSFS scores, reflecting higher self-rated ability in performing chosen daily life activities compared with patient’s current prosthesis. Standardized locomotor tests revealed comparable performance between devices. Biomechanical analyses showed similar symmetry indices for QUATTRO and other MPKs. Patient-reported outcomes showed an improvement in physical health with QUATTRO, while overall satisfaction remained similar. Conclusions: QUATTRO improved patient-perceived ability to perform meaningful daily-life activities while maintaining comparable performance on standardized locomotor tests. These results highlight the importance of patient-centered assessments in identifying functional benefits that may guide individualized prosthetic prescriptions for active transfemoral amputees. Full article

Background: Lower limb prosthesis users commonly exhibit gait asymmetry that may increase metabolic demand. Gait asymmetry, therefore, is frequently targeted in rehabilitation to improve walking efficiency. This review aimed to investigate whether interventions that improve gait asymmetry reduce metabolic demand in unilateral lower limb prosthesis users. Methods: A search of relevant English-language articles was conducted using PubMed and CINAHL, yielding a total of 1067 records. Following title, abstract, and full-text screening, 10 studies met eligibility requirements and were included in the qualitative synthesis. Data extraction focused on participant characteristics, gait asymmetry measures, metabolic outcomes, and intervention characteristics. Results: Four main intervention categories were identified: advanced prosthetic knees and ankles, prosthetic mass manipulation, feedback-based gait interventions, and exercise-based training. Across studies, changes in gait symmetry were not consistently associated with reductions in metabolic demand. Interventions targeting ankle function showed the most consistent reductions in metabolic demand, particularly during demanding walking tasks. In contrast, distal prosthetic mass addition consistently increased metabolic demand and worsened gait symmetry. Conclusion: Current evidence does not support a consistent or direct relationship between gait symmetry and metabolic demand in lower limb prosthesis users. Gait asymmetry may not be inherently metabolically disadvantageous and may represent an energetically optimal adaptation. Full article

Background: The natural motion of the human knee involves a combination of rotation and translation, resulting in a variable Instantaneous Center of Rotation (ICR) throughout the gait cycle. Traditional prosthetic knee designs often fail to reproduce this complex kinematic behavior. Objectives: This study aims to propose a customized, biomimetic knee mechanism through the synthesis of a four-bar linkage capable of approximating the physiological ICR trajectory with high precision. Methods: A Genetic Algorithm (GA) was implemented to optimize the geometric parameters of the four-bar mechanism, specifically its link lengths and inter-link angles. The optimization process is based on Freudenstein’s equation, which analytically relates the input and output angles of the linkage to the lengths of its links. The desired ICR trajectory was derived from experimental data, and the objective function minimized the Euclidean error between the generated and target trajectories. Results: The proposed method yielded customized mechanisms that closely approximate the target ICR curves, achieving an overall mean Euclidean tracking error of 1.95% (±1.68%) across diverse patient profiles, with a best-case optimization error as low as 0.355%. Furthermore, the GA demonstrated high computational efficiency, converging on optimal geometric configurations in an average execution time of just 3.98 min. Conclusions: These numerical results validate the robustness of the GA in navigating the design space while strictly adhering to kinematic constraints, Grashof’s condition, and anatomical motion limits. The integration of Freudenstein’s equation with GA-based optimization techniques enables the customized synthesis of four-bar linkages with a high capacity to reproduce the physiological kinematics of the knee. This computational approach could be highly beneficial for the design of polycentric knee prostheses, as it reduces design and manufacturing time by providing the initial parameters for the development of the four-bar mechanism, ultimately ensuring a better biomechanical fit between prosthetic and natural human movement. Full article

Background: The Mercer Universal Prosthesis (MUP), designed with a default “neutral” (vertical) socket alignment, was developed to simplify transtibial prosthetic fitting, reduce labor costs, and improve access to prosthetic care in low-resource settings. Methods: This present longitudinal study evaluated biomechanical and functional outcomes at baseline, 6 months, and 12 months in 20 transtibial amputees fitted with the MUP. Results: Functional outcomes, assessed using the SF-36, showed significant improvement in overall health scores at 12 months (p < 0.001), while physical function and energy/fatigue domains remained unchanged (p = 0.686 and p = 0.211, respectively). Biomechanically, sagittal kinematics, measured using inertial motion capture, revealed significant limb × time interactions for hip flexion, knee flexion, and ankle plantarflexion. At 6 months, maximum hip flexion (−7°, p = 0.008) and knee flexion (−11°, p = 0.005) of the prosthetic limb were decreased versus baseline. At 12 months, the only observed difference was increased maximum ankle plantarflexion of the intact limb (+5° vs. baseline, p = 0.016). Muscle effort, quantified via the integral of EMG throughout the gait cycle, did not differ significantly between prosthetic and intact limbs across time points. Gait symmetry index (GSI) scores for hip, knee, and ankle range of motion trended toward gradual improvement but without statistical significance (p > 0.05). Conclusions: The MUP performance was maintained over 12 months, with stable biomechanical performance and meaningful quality-of-life gains. These findings support its potential as a cost-effective solution to expand prosthetic accessibility in low- and middle-income countries. Full article

Objective: Serum albumin/creatinine ratio (sACR) integrates nutritional–inflammatory status and renal reserve. We evaluated its ability to predict 1-year reintervention for symptomatic graft occlusion in patients undergoing prosthetic above-knee femoropopliteal bypass for peripheral artery disease (PAD). Methods: This single-center retrospective study included 132 adults (7 women, 125 men) who underwent Dacron above-knee femoropopliteal bypass. The primary analysis evaluated preoperative sACR as a continuous variable. For descriptive comparisons and Kaplan–Meier visualization, patients were stratified according to the median preoperative sACR value (3.77), yielding two groups: <3.77 vs. ≥3.77. The primary endpoint was reintervention for symptomatic graft occlusion confirmed by imaging. Discrimination was assessed using ROC analysis, and the ROC-derived cutoff was interpreted as an exploratory threshold rather than a validated clinical decision point. Associations with 1-year reintervention were assessed using Cox proportional hazards regression analysis (age, diabetes, hypertension, smoking, coronary artery disease, hemodialysis-dependent chronic kidney disease, hemoglobin level, GFR, total protein level, antiplatelet use, and anticoagulant use). Results: Most baseline characteristics were comparable between groups; however, hemodialysis-dependent chronic kidney disease was more frequent in the low-sACR group. Reintervention occurred significantly more often in the low-sACR group from month 1 onward. sACR significantly discriminated 1-year events (AUC = 0.736; p < 0.001). The optimal cutoff was ≤3.7 (sensitivity 90.9%, specificity 64.6%). Higher sACR was associated with lower 1-year event risk in both univariate and multivariate models (adjusted HR 0.61, 95% CI 0.43–0.87; p = 0.007). Conclusions: Preoperative sACR is a practical biomarker associated with early and 1-year reintervention risk after prosthetic above-knee femoropopliteal bypass and may aid perioperative risk stratification. Full article

Magnetorheological (MR) dampers enable semi-active control in prosthetic knees by providing rapidly adjustable resistance with low mechanical complexity. This paper evaluates three torque level control methodologies for a transfemoral prosthetic leg incorporating an MR damper: a model-based feedforward strategy, an adaptive inverse-dynamics controller, and a robust inverse-dynamics controller. A Lagrange-based planar leg model with explicit force-to-torque mapping is formulated, and a reference knee trajectory is estimated from measurable gait variables using a cubic polynomial model whose order is selected through least-squares RMSE analysis. Each controller is assessed using knee-angle tracking accuracy and control effort to capture the practical trade-off between motion quality and energy demand. Results demonstrated that the adaptive inverse-dynamics controller has the smallest tracking error but requires the highest effort, whereas the robust inverse-dynamics approach realizes approximately the same tracking performance with reduced effort, thereby suggesting the best accuracy–effort compromise in the present work. Results, likewise, examined actuator feasibility by considering the MR damper as the primary dissipative element and the DC motor as a supplemental active actuator required when damping alone cannot satisfy the commanded knee torque. Full article

Background: Total knee arthroplasty in patients with hemophilia remains the most effective surgical intervention for end-stage hemophilic arthropathy, yet it poses unique surgical and perioperative challenges that are rarely encountered in standard osteoarthritis cases. This article synthesizes technical, anatomical, and perioperative considerations specific to hemophilic patients and integrates prospective clinical data derived exclusively from the hemophilic cohort of our long-term study (twenty patients, twenty knees; 2015–2024). Emphasis is placed on deformity correction, bone loss management, implant selection, hemostatic strategies, transfusion patterns, and perioperative pitfalls. The objective is to provide a comprehensive narrative reference for surgeons managing complex hemophilic knees, consolidating both evidence-based recommendations and practical perioperative “tips and tricks” accumulated across more than a decade of clinical experience. Methods: This prospective observational study evaluated twenty consecutive male patients with hemophilia who underwent primary total knee arthroplasty for advanced hemophilic arthropathy between 2015 and 2024 at our institution. The following variables were collected: operative time measured from skin incision to skin closure, postoperative transfusion requirement, length of hospitalization measured in days, early postoperative complications, and functional recovery as assessed by the Knee Society Score. Early complications included postoperative bleeding or hematoma, superficial or deep infection, and stiffness requiring intensive physiotherapy or manipulation under anesthesia. Results: The mean age at the time of surgery was 44.8 years with a standard deviation of 7.2 years, ranging from 31 to 59 years. The mean operative time in the hemophilic cohort was 154.54 min with a standard deviation of 18.36 min. The range of operative time was from 120 to 180 min. Nine of the twenty patients, representing 45 percent, required postoperative blood transfusion. The mean length of hospital stay in the hemophilic cohort was 12.3 days with a standard deviation of 2.38 days, ranging from 9 to 17 days. The mean Knee Society Score improved from 38 points preoperatively to 82 points at final follow-up, representing a mean increase of 44 points. Conclusions: Total knee arthroplasty in hemophilic patients is safe and effective when specialized surgical techniques, comprehensive synovectomy, precise deformity correction, optimized hemostasis, and structured postoperative coagulation factor replacement are implemented. Functional outcomes and prosthetic survival are excellent in experienced centers. Full article

Background/Objectives: Prosthetic joint infection following total knee arthroplasty remains a significant public health challenge. Automated surveillance systems are increasingly used for national monitoring of surgical site infections after arthroplasty. This study assessed the performance of the French ISO-ORTHO automated surveillance indicator after primary total knee arthroplasty by comparing automated surveillance data with exhaustive clinical follow-up. It also reported the incidence of surgical site infections during the initial years of activity of a tertiary care university hospital. Methods: A retrospective cohort analysis of primary total knee arthroplasties performed between January 2016 and December 2018 was conducted using exhaustive clinical chart review and the French ISO-ORTHO automated surveillance system. Prosthetic joint infections were diagnosed according to the 2018 International Consensus Meeting criteria. The local ISO-ORTHO results were compared with the national ISO-ORTHO rates. Results: Clinical chart review identified 1138 primary total knee arthroplasties and five prosthetic joint infections. Prosthetic joint infection incidence was 0.44% with a mean follow-up of 40.5 months. ISO-ORTHO was not yet implemented in 2016. Between 2017 and 2018, ISO-ORTHO identified 519 procedures and one prosthetic joint infection, compared with 807 procedures and three infections identified by clinical review. Conclusions: The French ISO-ORTHO surveillance indicator aided local and national monitoring of surgical site infections after total knee arthroplasty, but discrepancies with clinical chart review highlighted important limitations of automated monitoring and the importance of prolonged clinical follow-up. Future surveillance strategies could integrate these complementary approaches to improve prosthetic joint infection detection. Full article

Background: Perioperative antibiotic prophylaxis (PAP) is effective for infection prevention in implant-related surgery, with infections being the most feared complications. A total of 15% of all antibiotics in hospitals are used for surgical prophylaxis but less than 50% of them are used according to the guidelines. International guidelines recommend only a single preoperative dose for all surgical procedures. We have developed and implemented new recommendations for PAP duration in primary hip and knee arthroplasty at the University Department for Orthopaedic Surgery. Methods: The development and implementation of new recommendations regarding PAP duration were performed via the following steps: pre-interventional analysis; identification of barriers and facilitators using the Flottorp framework; analyzing the data and preparation of a tailored implementation strategy based on an educational group meeting with the development of new consented to recommendations; and dissemination; followed by postinterventional analysis of PAP duration compliance 6 months later. Results: Before the intervention, 70% of PAP was used inappropriately (longer than 24 h). The major recognized barriers were fear of prosthetic joint infection (PJI) and a lack of concern regarding global antimicrobial resistance problems. Major facilitators were a low local PJI incidence rate (0.28%), etiology of PJI and existing local experience with a single-dose regime. After implementation of new recommendations regarding the duration of PAP, the postinterventional analysis showed that 80% of PAP was used according to the new recommendations, with a significant reduction in prolonged PAP use (from 70% to 12%), leading to an important decline in antimicrobial consumption. Conclusions: Our study showed that a tailored strategy in the development and implementation of new recommendations is complex and time consuming, although necessary for successful clinical practice change. Full article

The available literature provides limited and inadequate data regarding the association between intraoperative knee kinematics, long-term clinical outcomes and survivorship after total knee arthroplasty (TKA). This study aimed to examine the potential relationship between specific intraoperative kinematics laxity assessment, acquired with a computer navigation system, and the long-term clinical outcomes and survivorship in patients undergoing TKA. This study consists of a retrospective cohort analysis of consecutive TKA procedures, in which a surgical navigation system was utilized to intra-operatively assess bone resections, implant positioning and gap balancing. The intraoperative kinematic parameters included varus-valgus laxity at 0° (VV 0) and 30° of flexion (VV 30), anterior–posterior displacement at 90° of flexion (AP 90), and passive range of motion (ROM). Different prosthesis designs were used, with a predominance of the posterior stabilized (PS)-type implant. The Knee Injury and Osteo-arthritis Outcome Score (KOOS) was used to investigate patients’ clinical and functional status. Survival was analyzed with the Kaplan–Meier method. Between-group comparisons were performed using the Mann–Whitney U test. A univariate logistic regression analysis was conducted to identify factors associated with clinical failure. Of 165 eligible patients, 120 were included in the final analysis, with a mean follow-up of 7.7 ± 2.8 years. Revision surgery was required in seven cases, representing surgical failure and an overall survival rate of 94.2%, with survival probabilities of 98.8%, 97.4%, and 93.6% at 6, 8, and 10 years, respectively. Clinical failure (KOOS < 70 in three domains) occurred in 23 patients. No intra-operative surgical parameters, including Hip-Knee-Ankle angle, Preoperative KL grade, prostheses design, VV 0, VV 30, AP 90 and ROM, or demographic variables, were found to be statistically correlated with clinical failure at follow-up. Although, in this navigated TKA cohort, survivorship was acceptable and consistent with previously reported benchmarks, it was not possible to reliably predict survival probability based solely on the intra-operative laxity parameters measured. Nevertheless, the use of surgical navigation can help surgeons accurately assess bone resections and the balance of prosthetic components. Full article

Objective: This study investigates the optimization of surface EMG (sEMG) classification for seven transtibial movements using short analysis windows (64 ms) suitable for real-time control of below-knee prostheses. Methods: We systematically evaluated feature engineering strategies, dimensionality reduction techniques, and classification approaches using linear Support Vector Machines on four-channel sEMG data from the transtibial region. We compared amplitude-based versus derivative-based time-domain features, integrated frequency-domain features, and implemented multi-window majority voting with 50% overlap. Results: Evaluated across nine subjects (four male, five female), the optimized system achieves a population-level accuracy of $70.16\%\pm 7.09\%$ with multi-window majority voting (per-subject range: 60.71–78.57%), with voting consistently improving accuracy over single-window classification by $+7.06$% on average. We demonstrate that PCA provides zero benefit for linear classifiers when all features are retained. Documented failed approaches include adaptive windowing and spectral entropy features. Conclusion: Careful feature engineering combining time-domain (MAV2, RMS, VAR, MAX, LOG, IEMG) and frequency-domain features (MPF, MF, band powers) with multi-window voting substantially recovers accuracy losses from aggressive window reduction while maintaining sub-100 ms latency suitable for prosthetic control. This work provides a validated methodology across multiple subjects for optimizing EMG classification latency–accuracy trade-offs, demonstrates that PCA is unnecessary for linear classifiers with well-engineered features, and documents negative results to guide future prosthetic control research. Full article

Background: Peri-prosthetic joint infection (PJI) following total knee arthroplasty complicated by soft tissue compromise presents a major reconstructive challenge. Successful management requires the eradication of infection while restoring durable soft tissue coverage and limb function. This study reports the outcomes of a patient-specific, multidisciplinary orthoplastic approach to complex knee PJI. Methods: We retrospectively reviewed five patients with complex infected knee arthroplasty and associated soft tissue compromise managed at our institution between 2021 and 2025 by a single orthopaedic surgeon and two plastic reconstructive surgeons. All cases required personalized management, including the use of custom spacers, patient-specific orthopaedic reconstruction, and individualized soft tissue reconstruction techniques. Data collected included patient demographics, infection characteristics, reconstructive techniques, and functional outcomes. Results: All patients achieved durable soft tissue coverage and infection eradication at final follow-up. Of the five patients, one underwent primary closure of a persistent sinus, one required a local axial bi-pedicled flap for sinus control and soft tissue closure, two were managed with medial gastrocnemius flaps, and one complex case with an associated bone defect required a custom-designed spacer to achieve stability and dead-space management. Conclusions: In this retrospective case series, we aim to demonstrate that complex knee PJI with associated soft tissue defects may be successfully managed with an individualized, multidisciplinary strategy. We aim to demonstrate the feasibility of such an approach in a tertiary referral centre and to highlight the importance of customisation in achieving infection control and limb preservation. Full article

Compliant mechanisms have contributed to many advances in soft robotics, and there is strong motivation to translate these ideas to assistive devices where adaptive motion at the human interface is required. This work presents novel reconfigurable compliant joints (RCJs) as a parameterized joint element for functional biomimicry in lower-extremity joints for prosthetic knees and ankle–foot orthoses, with concepts that extend to other limb joints. The RCJ uses a rigid hub and outer ring joined by an array of flexible links with centerlines defined by cubic Bézier curves. Link shapes are organized into four Bézier classes (A–D), with base types using 10, 12, or 14 uniformly distributed link slots and variants generated by modifying active-link count and distribution, forming a structured morphology space of 12 configurations for machine design. Dual-extrusion 3D-printed prototypes are characterized by a custom testing apparatus using a 2.2 kN load cell at 25 mm/s over a 0–90° rotation range across six recorded load cycles to measure torque–angle curves and stiffness under large deformations. Angle-dependent stiffness is evaluated over three fixed intervals (0–30°, 30–60°, and 60–90°) to quantify multi-stage behavior. A 2-dimensional corotational frame model and a Simscape Multibody model, including a rolling-contact knee configuration, use the same parameterization to relate geometry, nonlinear mechanics, and system-level motion. Experiments and simulations show multi-stage torque–angle profiles and predictable stiffness modulation across all configurations, with both magnitude and transition angle tunable through Bézier class and active-link distribution, positioning the RCJ as a CAD/CAE-compatible joint architecture for assistive devices or wearable robotic systems and a basis for advancing functional biomimicry in compliant mechanism design. Full article