Search

Bone-anchored limbs (BALs) are socket prosthesis alternatives, directly fixing to residual bone via osseointegrated implant. There is a need to quantify multi-level effects of rehabilitation for transfemoral BAL users (i.e. changes in joint loading and movement patterns). Our primary objective was determining feasibility of using optimal control to predict gait biomechanics compared to ground-truth experimental data from transfemoral BAL users. A secondary objective was examining biomechanical effects from estimated changes in hip abductor muscle strength. We developed and validated a workflow for predicting gait biomechanics in four transfemoral BAL users and investigated the biomechanical effects of altered hip abductor strengths.

Background: A bone-anchored limb (BAL) is an alternative to a traditional socket-type prosthesis for people with transfemoral amputation. Early laboratory-based evidence suggests improvement in joint and limb loading mechanics during walking with a BAL compared to socket prosthesis use. However, changes in cumulative joint and limb loading measures, which may be predictive of degenerative joint disease progression, remain unknown., Research Question: Do cumulative total limb and hip joint loading during walking change using a BAL for people with unilateral transfemoral amputation, compared to prior socket prosthesis use?, Methods: A case-series cohort of eight participants with prior unilateral transfemoral amputation who underwent BAL hardware implantation surgery were retrospectively analyzed (4 M/4 F; BMI: 27.7 ± 3.1 kg/m 2 ; age: 50.4 ± 10.2 years). Daily step count and whole-body motion capture data were collected before (using socket prosthesis) and one-year after BAL hardware implantation. Cumulative total limb and hip joint loading and between-limb loading symmetry metrics were calculated during overground walking at both time points and compared using Cohen's d effect sizes., Results: One year after BAL hardware implantation, participants demonstrated bilateral increases in cumulative total limb loading (amputated: d = -0.65; intact: d = -0.72) and frontal-plane hip moment (amputated: d = -1.29; intact: d = -1.68). Total limb loading and hip joint loading in all planes remained asymmetric over time, with relative overloading of the intact limb in all variables of interest at the one-year point., Significance: Despite increases in cumulative total limb and hip joint loading, between-limb loading asymmetries persist. Habitual loading asymmetry has been implicated in contributing to negative long-term joint health and onset or progression of degenerative joint diseases. Improved understanding of methods to address habitual loading asymmetries is needed to optimize rehabilitation and long-term joint health as people with transfemoral amputation increase physical activity when using a BAL., Competing Interests: Declaration of Competing Interest The authors declare that they have no known conflicting financial or personal interests that could have appeared to inappropriately influence the results presented in this work., (Published by Elsevier B.V.)

Objective: People with Marfan syndrome (MFS) have clinical symptoms of hip pain, but to date, there is limited knowledge about hip-related structural abnormalities in these patients. Therefore, the purpose of this cross-sectional study was to assess hip-related structural abnormalities and patient-reported outcomes (PRO) in a cohort of patients with MFS compared to healthy controls., Methods: Nineteen individuals with MFS (17 females, 39.8±11.5 years) and 19 age, sex, and body mass index-matched healthy, asymptomatic individuals (17 females, 36.2±12.5 years) underwent radiographic imaging and unilateral hip MRI. The Scoring Osteoarthritis with MRI (SHOMRI) technique was used to assess hip-related morphological abnormalities between the MFS and control groups. All participants completed the Hip disability and Osteoarthritis Outcome Score (HOOS) to assess hip-related symptoms, pain, and function during activities of daily living (ADL) and quality of life (QOL)., Results: The MFS group exhibited higher lateral center edge angles (p < .001). Despite similar severity of femoral cartilage damage (p = 1.0), the MFS group exhibited a higher severity (p = 0.046) of acetabular cartilage degeneration (1.21±1.08) compared to the controls (0.53±1.02). There were no between-group differences in severity of labral pathology, subchondral cysts, or edema. Individuals with MFS also self-reported significantly lower HOOS symptoms (p = 0.003), pain (p = 0.014), ADL (p = 0.028), and QOL (p = 0.014) sub-scores, indicating worse hip-related PRO in MFS., Conclusion: Our study results suggest that individuals with MFS exhibit early signs of acetabular cartilage degeneration and poor hip-related clinical outcomes compared to healthy individuals. Future work should investigate the underlying biomechanical mechanisms associated with hip joint degeneration in the MFS population., (© 2024. The Author(s), under exclusive licence to International Skeletal Society (ISS).)

For some individuals with severe socket-related problems, prosthesis osseointegration directly connects a prosthesis to the residual limb creating a bone-anchored limb (BAL). We compared dynamic gait stability and between-limb stability symmetry, as measured by the Margin of Stability (MoS) and the Normalized Symmetry Index (NSI), for people with unilateral transfemoral amputation before and one-year after BAL implantation. The MoS provides a mechanical construct to assess dynamic gait stability and infer center of mass and limb control by relating the center of mass and velocity to the base of support. Before and one-year after BAL implantation, 19 participants walked overground at self-selected speeds. We quantified dynamic gait stability anteriorly and laterally at foot strike and at the minimum lateral MoS value. After implantation, we observed decreased lateral MoS at foot strike for the amputated (MoS mean(SD) %height; pre: 6.6(2.3), post: 5.9(1.3), d = 0.45) and intact limb (pre: 6.2(1.2), post: 5.8(1.0), d = 0.38) and increased between-limb MoS symmetry at foot strike (NSI mean(SD) %; anterior-pre: 10.3(7.3), post: 8.4(3.6), d = 0.23; lateral-pre: 18.8(12.4), post: 12.4(4.9), d = 0.47) and at minimum lateral stability (pre: 28.1(18.1), post: 19.2(6.8), d = 0.50). Center of mass control using a BAL resulted in dynamic gait stability more similar between limbs and may have reduced the adoption of functional asymmetries. We suggest that improved between-limb MoS symmetry after BAL implantation is likely due to subtle changes in individual limb MoS values at self-selected walking speeds resulting in an overall positive impact on fall risk through improved center of mass and prosthetic limb control., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: [Dr. Jason W. Stoneback is a paid consultant for AQ Solutions. No additional competing financial or non-financial interests which could or appear to influence the interpretation or presentation of this work are declared]., (Published by Elsevier Ltd.)

Purpose: People with lower-limb loss participate in less physical activity than able-bodied individuals, which increases the mortality risk and incidence of metabolic syndromes. This study evaluated the effect of lower-limb prosthesis osseointegration on physical activity, including daily steps and stepping cadence., Methods: Free-living walking activity was assessed from 14 patients scheduled to undergo prosthesis osseointegration at two time points (within 2 weeks prior to osseointegration surgery and 12-months following). Daily step count, stepping time, number of walking bouts, average step cadence per bout, maximum step cadence per bout, and time spent in bands of step cadence were compared before and after osseointegration., Results: Twelve months after prosthesis osseointegration, participants increased daily steps, daily stepping time, average step cadence, and maximum cadence per walking bout compared to pre-osseointegration., Conclusions: Participants engaged in more daily steps, higher stepping cadence, and longer bouts at higher cadence one year following osseointegration compared to when using a socket prosthesis. As a novel intervention that is becoming more common, it is important to understand walking activity outcomes as these are critical for long-term health.

» Patient-reported outcome measures (PROMs) are essential for measuring quality and functional outcomes after implantation of osseointegrated bone anchored limbs for patients with lower extremity amputation.» Using a novel assessment criterion with 8 domains, this study assessed all commonly used PROMs for their efficiency and comprehensiveness.» Comprehensiveness was scored according to the presence or absence of PROM questions related to these 8 domains (maximum score = 60): mobility (15 items), prosthesis (14 items), pain (10 items), psychosocial status (10 items), independence/self-care (4 items), quality of life/satisfaction (4 items), osseoperception (1 item), general information (1 item), and vitality (1 item).» The efficiency scores were calculated by dividing the comprehensiveness score by the total number of questions answered by the patients with higher scores being deemed more efficient.» The most comprehensive PROMs were Orthotics and Prosthetics User's Survey-Lower Extremity Functional Status (OPUS-LEFS) (score = 36), Prosthesis Evaluation Questionnaire (PEQ) (score = 31), and Questionnaire for Persons with a Transfemoral Amputation (score = 27).» The most efficient PROMs were the OPUS-LEFS (score = 1.8) and European Quality of Life (score = 1.4)., Competing Interests: Disclosure: The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article (http://links.lww.com/JBJSREV/B76)., (Copyright © 2024 by The Journal of Bone and Joint Surgery, Incorporated.)

Patients with transfemoral amputation (TFA) are at an increased risk of secondary musculoskeleteal comorbidities, primarily due to asymmetric joint loading. Amputated limb muscle weakness is also prevalent in the TFA population, yet all factors that contribute to muscle strength and thus joint loading are not well understood. Our objective was to bilaterally compare gluteus medius (GMED) muscle factors (volume, fatty infiltration, moment arm) that all contribute to joint loading in patients with TFA. Quantitative magnetic resonance (MR) images of the hip were collected from eight participants with unilateral TFA (2M/6F; age: 47.3 ± 14.7 y/o; BMI: 25.4 ± 5.3 kg/m 2 ; time since amputation: 20.6 ± 15.0 years) and used to calculate normalized GMED muscle volume and fatty infiltration. Six participants participated in an instrumented gait analysis session that collected whole-body kinematics during overground walking. Subject-specific musculoskeletal models were used to calculate bilateral GMED (anterior, middle, posterior) moment arms and frontal plane hip joint angles across three gait cycles. Differences in volume, fatty infiltration, hip adduction-abduction angle, and peak moment arms were compared between limbs using paired Cohen's d effect sizes. Volume was smaller by 36.3 ± 18.8% (d = 1.7) and fatty infiltration was greater by 6.4 ± 7.8% (d = 0.8) in the amputated limb GMED compared to the intact limb. The amputated limb GMED abduction moment arms were smaller compared to the intact limb for both overground walking (anterior: d = 0.9; middle: d = 0.1.2) and during normal range of motion (anterior: d = 0.8; middle: d = 0.8) while bilateral hip adduction-abduction angles were similar during overground walking (d = 0.5). These results indicate that in patients with TFA, the amputated limb GMED is biomechanically disadvantaged compared to the intact limb, which may contribute to the etiology of secondary comorbidities. This population might benefit from movement retraining to lengthen the amputated limb GMED abduction moment arm during gait., (© 2023. The Author(s) under exclusive licence to Biomedical Engineering Society.)

Background: Low back pain (LBP) is more prevalent in patients with transfemoral amputation using socket prostheses than able-bodied individuals, in part due to altered spinal loading caused by aberrant lumbopelvic movement patterns. Early evidence surrounding bone-anchored limb functional outcomes is promising, yet it remains unknown if this novel prosthesis influences LBP or movement patterns known to increase its risk., Research Question: How are self-reported measures of LBP and lumbopelvic movement coordination patterns altered when using a unilateral transfemoral bone-anchored limb compared to a socket prosthesis?, Methods: Fourteen patients with unilateral transfemoral amputation scheduled to undergo intramedullary hardware implantation for bone-anchored limbs due to failed socket use were enrolled in this longitudinal observational cohort study (7 F/7 M, Age: 50.2±12.0 years). The modified Oswestry Disability Index (mODI) (self-reported questionnaire) and whole-body motion capture during overground walking were collected before (with socket prosthesis) and 12-months following bone-anchored limb implantation. Lumbopelvic total range of motion (ROM) and continuous relative phase (CRP) segment angles were calculated during 10 bilateral gait cycles. mODI, total ROM, CRP and CRP variabilities were compared between time points., Results: mODI scores were significantly reduced 12-months after intramedullary hardware implantation for the bone-anchored limb (P = 0.013). Sagittal plane trunk and pelvis total ROM during gait were reduced after implantation (P = 0.001 and P < 0.001, respectively). CRP values were increased (more anti-phase) in the sagittal plane during single limb stance and reduced (more in-phase) in the transverse plane during pre-swing of the amputated limb gait cycle (P << 0.001 and P = 0.029, respectively). No differences in CRP values were found in the frontal plane., Significance: Decreases in mODI scores and lumbopelvic ROM, paired with the changes in lumbopelvic coordination, indicate that bone-anchored limbs may reduce LBP symptoms and reduce compensatory movement patterns for people with unilateral transfemoral amputation., Competing Interests: Declaration of Competing Interest The authors have no conflicts of interest to disclose., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Femoral deformities are common in developmental dysplasia of the hip (DDH), but decisions about how to treat them are not standardized. Of interest are deformities that may be akin to cam femoroacetabular impingement (FAI). We used three-dimensional and two-dimensional measures to clarify the similarities and differences in proximal femur shape variation among female patients with DDH ( n  = 68) or cam FAI ( n  = 60). Three-dimensional measures included femoral head asphericity, as well as shape variation using statistical shape modeling and principal component analysis (PCA). Two-dimensional measures included the α-angle, head-neck offset (HNO) and the neck-shaft angle (NSA). Significant shape variations were captured in the first five PCA modes, with the greatest shared variation between groups being the length from the lesser trochanter to the femoral head and greater trochanter height. Variations unique to DDH were irregularities at different areas of the femoral head, but not at the lateral femoral head-neck junction where variation was strong in FAI. The FAI group also had unique variations in greater trochanter shape. DDH femoral heads were less spherical, as indicated by larger sphere-fitting errors ( P  < 0.001). Radiographically, the DDH group had significantly smaller α-angles ( P  < 0.001), larger head-neck offsets ( P  = 0.02) and larger NSAs ( P  < 0.001). Both the articular and extra-articular regions of the proximal femur have distinct shape features in DDH and cam FAI that can uniquely affect the biomechanics of each disorder. Accordingly, approaches to addressing each disorder should be unique., Competing Interests: None declared., (© The Author(s) 2024. Published by Oxford University Press.)

Objective: This randomized controlled superiority trial will determine if an 18-month telehealth walking exercise self-management program produces clinically meaningful changes in walking exercise sustainability compared to attention-control education for veterans living with lower-limb amputation., Methods: Seventy-eight participants with lower-limb amputation (traumatic or nontraumatic) aged 50 to 89 years will be enrolled. Two groups will complete 6 one-on-one intervention sessions, and 6 group sessions over an 18-month intervention period. The experimental arm will receive a self-management program focusing on increasing walking exercise and the control group will receive attention-control education specific to healthy aging. Daily walking step count (primary outcome) will be continuously monitored using an accelerometer over the 18-month study period. Secondary outcomes are designed to assess potential translation of the walking exercise intervention into conventional amputation care across the Veteran Affairs Amputation System of Care. These secondary outcomes include measures of intervention reach, efficacy, likelihood of clinical adoption, potential for clinical implementation, and ability of participants to maintain long-term exercise behavior., Impact: The unique rehabilitation paradigm used in this study addresses the problem of chronic sedentary lifestyles following lower-limb amputation through a telehealth home-based walking exercise self-management model. The approach includes 18 months of exercise support from clinicians and peers. Trial results will provide rehabilitation knowledge necessary for implementing clinical translation of self-management interventions to sustain walking exercise for veterans living with lower-limb amputation, resulting in a healthier lifestyle., (© The Author(s) 2023. Published by Oxford University Press on behalf of the American Physical Therapy Association. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Background: People with lower-limb amputation (LLA) are routinely prescribed a socket prosthesis; however, many socket prosthesis users experience severe complications with the fit of their prosthesis including residual limb wounds and pain. Osseointegration is a procedure that creates a direct connection between the bone and prosthetic limb through a bone-anchored prosthesis, eliminating the need for a socket interface. It is offered as a secondary procedure to people with LLA who experience significant complications with socket prostheses., Objectives: To evaluate change in disability and function 1 year postosseointegration compared with preosseointegration in people with LLA., Study Design: Single group, pretest, and post-test., Methods: Twelve participants (9 transfemoral and 3 transtibial amputations, age: 44 ± 10 years, 7 female participants, 14 ± 12 years since amputation) with unilateral LLA underwent osseointegration with press-fit implants. Disability was measured with the World Health Organization Disability Assessment Schedule 2.0, and function was measured with both Prosthetic Limb Users Mobility Survey and the Activities-Specific Balance Confidence Scale. Questionnaires were administered preosseointegration and 1 year postosseointegration. Paired t tests assessed change in outcomes between time points., Results: Postosseointegration, participants demonstrated reduced disability measured with World Health Organization Disability Assessment Schedule 2.0 (%Δ = -52.6, p = 0.01), improved mobility measured with Prosthetic Limb Users Mobility Survey (%Δ = 21.8, P < 0.01), and improved balance confidence measured with the Activities-Specific Balance Confidence Scale (%Δ = 28.4, P < 0.01)., Conclusions: Participants report less disability and greater function in their prosthesis postosseointegration. Osseointegration is a novel procedure for people experiencing complications with their socket prosthesis, and this study is the first to show improvements in disability postosseointegration., (Copyright © 2022 International Society for Prosthetics and Orthotics.)

Patients with transfemoral amputation (TFA) are up to six times more likely to develop hip osteoarthritis (OA) in either or both the intact and residual limb, which is primarily attributed to habitually altered joint loading due to compensatory movement patterns. However, joint loading patterns differ between limbs, which confounds the understanding of loading-induced OA etiology across limbs. It remains unknown if altered loading due to amputation results in bony shape changes at the hip, which is a known etiological factor in the development of hip OA. Retrospective computed tomography images were collected of the residual limb for 31 patients with unilateral TFA (13F/18M; age: 51.7 ± 9.9 y/o; time since amputation: 13.7 ± 12.4 years) and proximal femur for a control group of 29 patients (13F/16M; age: 42.0 ± 12.27 years) and used to create 3D geometries of the proximal femur. Femoral 3D geometric variation was quantified using statistical shape modeling (SSM), a computational tool which placed 2048 corresponding particles on each geometry. Independent modes of variation were created using principal component analysis. 2D radiographic measures of the proximal femur, including common measures such as α-angle, head neck offset, and neck shaft angle, were quantified on digitally reconstructed radiographs (DRRs). SSM results were then compared to 2D measures using Pearson correlation coefficients (r). Two-sample t-tests were used to determine if there were significant differences between the TFA and control group means of 2D radiographic measurements (p < 0.05). Patients with TFA had greater femoral head asphericity within the SSM, which was moderately correlated to head-neck offset (r = -0.54) and α-angle (r = 0.63), as well as greater trochanteric torsion, which was strongly correlated to the novel radiographic measure of trochanteric torsion (r = -0.78), compared to controls. For 2D measures, the neck-shaft angle was smaller in the TFA group compared to the control group (p = 0.01) while greater trochanter height was larger in the TFA group compared to the control group (p = 0.04). These results indicate altered loading from transfemoral prosthesis use changes proximal femur bony morphology, including femoral head asphericity and greater trochanter changes. Greater trochanter morphologic changes, though not a known factor to OA, affect moment arm and line of action of the primary hip abductors, the major muscles which contribute to joint loading and hip stability. Thus, chronic altered loading of the amputated limb hip, whether under- or overloading, results in bony changes to the proximal femur which may contribute to the etiological progression and development of OA., Competing Interests: Declaration of competing interest There are no competing interests to disclose., (Copyright © 2023 Elsevier Inc. All rights reserved.)

People with unilateral transfemoral amputation using socket prostheses are at increased risk for developing osteoarthritis in both the residual hip and intact lower-limb joints. Osseointegrated prostheses are a surgical alternative to socket prostheses that directly attach to the residual femur via a bone-anchored implant, however their multi-joint loading effect is largely unknown. Our objective was to establish how osseointegrated prostheses influence joint loading during walking. Motion capture data (kinematics, ground reaction forces) were collected from 12 participants at baseline, with socket prostheses, and 12-months after prosthesis osseointegration during overground walking at self-selected speeds. Subject-specific musculoskeletal models were developed at each timepoint relative to osseointegration. Internal joint moments were calculated using inverse dynamics, muscle and joint reaction forces (JRFs) were estimated with static optimization. Changes in internal joint moments, JRFs, and joint loading-symmetry were compared using statistical parametric mapping (p≤ 0.05) before and after osseointegration. Amputated limb hip flexion moments and anterior JRFs decreased during terminal stance (p = 0.002, <0.001; respectively), while amputated limb hip abduction moments increased during mid-stance (p < 0.001), amputated hip rotation moment changed from internal to external throughout early stance (p < 0.001). Intact limb hip extension and knee flexion moments (p = 0.028, 0.032; respectively), superior and resultant knee JRFs (p = 0.046, 0.049; respectively) decreased during the loading response following prosthesis osseointegration. These results may indicate that the direct loading transmission of these novel prostheses create a more typical mechanical environment in bilateral joints, which is comparable with loading observed in able-bodied individuals and could decrease the risk of development or progression of osteoarthritis., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Background: Dissatisfaction with socket prostheses has led to the development of bone-anchored prostheses through osseointegration for people with transfemoral amputation, eliminating the need for a prosthetic socket. Gait deviations of transfemoral prosthesis users may be linked to increased risk of osteoarthritis, and it remains unknown if gait biomechanics change following osseointegration. The purpose of this case series was to evaluate the longitudinal changes in joint kinetics one year post-osseointegration in patients with transfemoral amputation during walking., Methods: Knee, hip, and trunk internal moments were evaluated in the prosthetic and intact limbs during walking at a self-selected speed in four participants pre- and one-year post-osseointegration. Longitudinal changes were quantified using the percent change (%∆) in peak joint moments between the two time points and Cohen's d (d) effect size was used to determine the magnitude of effect on joint moments during walking one year following osseointegration., Findings: Participants demonstrated increased peak knee extension moment (224 ± 308%∆, d = -1.31) in the prosthetic limb, while demonstrating reduced peak knee extension moment (-43 ± 34%∆, d = 1.82) in the intact limb post-osseointegration. Participants demonstrated bilateral reduction of peak hip extension moment (prosthetic: -22 ± 37%∆, d = 0.86; intact: -29 ± 10%∆, d = 1.27) and bilateral increase of peak hip abduction moment (prosthetic: 45 ± 40%∆, d = 1.20; intact: 23 ± 44%∆, d = 0.74) post-osseointegration. Participants demonstrated reduced peak trunk moments on both the prosthetic (extension: -31 ± 16%∆, d = 1.51; lateral flexion: -21 ± 20%∆, d = 0.63) and intact side (extension: -7 ± 22%∆, d = 0.38; lateral flexion: -22 ± 18%∆, d = 1.12) post-osseointegration., Interpretation: This case series suggests improved gait symmetry in individuals with transfemoral amputation one year following osseointegration, justifying future investigation., Competing Interests: Declaration of Competing Interest Dr. Jason Stoneback serves as a consultant for Revivo, an osseointegration device company, and Exer Al, a software company that investigates rehabilitation in osseointegration. Dr. Stoneback is a stake shareholder and receives funding from Exer Al. All other authors declare that they have no known conflicting financial interests or personal relationships that have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Ltd.)

Background: More than half of patients with lower-limb amputation who use socket prostheses experience at least one fall annually. These falls are primarily attributed to reduced proprioception which negatively affects balance. A promising alternative to socket prostheses are osseointegrated prostheses that involve direct fixation of the prosthetic limb to the residual limb through a bone-anchored implant, yet its effect on balance remains unknown., Research Question: Do osseointegrated prostheses change static and dynamic balance, as well as patient reported measures of balance confidence, compared to a socket prosthesis?, Methods: A sample of 10 patients with unilateral transfemoral amputation scheduled to undergo prosthesis osseointegration were enrolled (6 F/4 M, BMI: 26.7 ± 2.9 kg/m 2 , Age: 46.1 ± 6.3 years). Motion capture data during quiet standing (eyes opened and eyes closed) and overground walking at a self-selected speed, and the Activities-Specific Balance Confidence (ABC) scale, were collected before (with socket prosthesis) and 12-months following osseointegration. Postural sway via the center of pressure (COP), variability of spatiotemporal parameters, and ABC scores were compared using a repeated measures design before and after osseointegration., Results: Following prosthesis osseointegration, COP path length and 95 % confidence ellipse area were reduced during quiet standing (d = 0.75, P = 0.09; d = 0.52, P = 0.29, respectively) and the variability of step width and length were reduced during overground walking (d = 0.50, P = 0.06; d = 0.72, P = 0.06, respectively). Furthermore, patients reported significantly improved ABC scores with an osseointegrated prosthesis compared to a socket prosthesis (d = -1.36, P = 0.01)., Significance: Improvements in postural sway, reductions in gait variability, and greater balance confidence indicate that osseointegrated prostheses improve balance for people with unilateral transfemoral amputation., Competing Interests: Conflict of Interest Statement The authors have no conflicts of interest to disclose., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Gender biases and inequities are prevalent across many scientific fields and biomechanics is likely no exception. While progress has been made to support women in the field, especially at biomechanics society conferences, the recent COVID-19 pandemic has exacerbated professional isolation. The International Women in Biomechanics (IWB) community started in July 2020 with the mission of fostering an environment for women and other under-represented genders in biomechanics to gain year-round support, visibility, and allyship. Nearly 700 biomechanists have joined the IWB community from over 300 universities/organizations and 33 countries. Our community ranges in career stages and professions and interacts through a forum-style platform, teleconference meetings, and social media. In 2021, we conducted a survey to identify the needs, concerns, and issues faced by individuals in the IWB community. We received 144 responses from members in 16 countries. Our survey revealed three primary needs for women in biomechanics: supportive working environments, career planning support, and addressing workplace gender bias. These results, in conjunction with scientific evidence on workforce gender bias, helped us identify three key areas to meet our mission: Member Support, Community Outreach, and Empowering Allyship. Several levels of support are required in these three areas to ensure a lasting, positive, and sustainable impact on gender equity in biomechanics. We conclude by providing our perspectives on an evidence-based call to action to continue addressing gender bias and inequity at the individual, institutional, and scientific society levels. These actions can collectively enhance our allyship for women in the field of biomechanics., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Cartilage contact pressures are major factors in osteoarthritis etiology and are commonly estimated using finite element analysis (FEA). FEA models often include subject-specific joint geometry, but lack subject-specific joint kinematics and muscle forces. Musculoskeletal models use subject-specific kinematics and muscle forces but often lack methods for estimating cartilage contact pressures. Our objective was to adapt an elastic foundation (EF) contact model within OpenSim software to predict hip cartilage contact pressures and compare results to validated FEA models. EF and FEA models were built for five subjects. In the EF models, kinematics and muscle forces were applied and pressure was calculated as a function of cartilage overlap depth. Cartilage material properties were perturbed to find the best match to pressures from FEA. EF models with elastic modulus = 15 MPa and Poisson's ratio = 0.475 yielded results most comparable to FEA, with peak pressure differences of 4.34 ± 1.98 MPa (% difference = 39.96 ± 24.64) and contact area differences of 3.73 ± 2.92% (% difference = 13.4 ± 11.3). Peak pressure location matched between FEA and EF for 3 of 5 subjects, thus we do not recommend this model if the location of peak contact pressure is critically important to the research question. Contact area magnitudes and patterns matched reasonably between FEA and EF, suggesting that this model may be useful for questions related to those variables, especially if researchers desire inclusion of subject-specific geometry, kinematics, muscle forces, and dynamic motion in a computationally efficient framework., (© 2022. The Author(s) under exclusive licence to Biomedical Engineering Society.)

Background: Patients with transfemoral amputation and socket prostheses are at a heightened risk of developing musculoskeletal overuse injuries, commonly due to altered joint biomechanics. Osseointegrated prostheses, which involve direct anchorage of the prosthesis to the residual limb through a bone anchored prosthesis, are a novel alternative to sockets yet their biomechanical effect is largely unknown., Methods: Four patients scheduled to undergo unilateral transfemoral prosthesis osseointegration completed two data collections (baseline with socket prosthesis and 12-months after prosthesis osseointegration) in which whole-body kinematics and ground reaction forces were collected during stand-to-sit tasks. Trunk, pelvis, and hip kinematics, and the surrounding muscle forces, were calculated using subject-specific musculoskeletal models developed in OpenSim. Peak joint angles and muscle forces were compared between timepoints using Cohen's d effect sizes., Findings: Compared to baseline with socket prostheses, patients with osseointegrated prostheses demonstrated reduced lateral trunk bending (d = 1.46), pelvic obliquity (d = 1.09), and rotation (d = 1.77) toward the amputated limb during the stand to sit task. This was accompanied by increased amputated limb hip flexor, abductor, and rotator muscle forces (d> > 0.8)., Interpretation: Improved lumbopelvic movement patterns and stabilizing muscle forces when using an osseointegrated prosthesis indicate that this novel prosthesis type likely reduces the risk of the development and/or progression of overuse injuries, such as low back pain and osteoarthritis. We attribute the increased muscle hip muscle forces to the increased load transmission between the osseointegrated prosthesis and residual limb, which allows a greater eccentric ability of the amputated limb to control lowering during the stand-to-sit task., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Developmental dysplasia of the hip (DDH) is strongly associated with an increased risk for hip osteoarthritis. Skeletal deformities undeniably contribute to detrimental biomechanical loading in dysplastic hips, but cannot explain all types of damage and symptoms that patients with DDH experience. Characterizing the geometry and function of the muscles spanning the hip is a logical next step in our progression of knowledge about DDH pathomechanics. In this study, we compared skeletal geometry, muscle volumes, intramuscular fatty infiltration, moment arms, and isometric strength in patients with DDH (N = 20) to healthy controls (N = 15). Femoral coverage was significantly less in patients (p < 0.001, Cohen's d effect size = 2.2), femoral neck-shaft angles were larger (p = 0.001, d = 1.3), and hip joint centers (HJCs) were more lateral (p = 0.001, d = 1.3). These skeletal abnormalities were associated with smaller abductor muscle moment arms in patients with DDH (e.g., gluteus medius [GMED]: p = 0.001, d = 1.2). Patients with DDH also had larger GMED volumes (p = 0.02, d = 0.83), but no differences in fatty infiltration, compared to controls. Isometric strength of the hip abductors, extensors, and flexors was lower in patients, but not significantly different from controls. The abnormal skeletal geometry, lateralized HJC, and reduced muscle moment arms represent a chronic biomechanical disadvantage under which patients with DDH operate. This phenomenon causes increased demand on the abductor muscles and results in high medially and superiorly directed joint reaction forces, which can explain reports of superomedial femoral cartilage damage in patients. The abnormal muscle geometry and function, in context with abnormal skeletal structure, are likely strong, but underappreciated, contributors to damaging loads in DDH., (© 2021 Orthopaedic Research Society. Published by Wiley Periodicals LLC.)

Developmental dysplasia of the hip (DDH) causes hip instability and early-onset osteoarthritis. The focus on pathomechanics in DDH has centered on the shallow acetabulum, however there is growing awareness of the role of femoral deformities in joint damage. The objective of this study was to determine the influence of femoral version (FV) on the muscle and joint reaction forces (JRFs) of dysplastic hips during gait. Magnetic resonance images, in-vivo gait data, and musculoskeletal models were used to calculate JRFs and simulate changes due to varying FV deformities. Rotation about the long axis of the femur was added in the musculoskeletal models to simulate FV values from -5° (relative retroversion) to + 35° (increased anteversion). In our simulations, FV deformities caused the largest changes to the anteroposterior and resultant JRFs. From a normal FV of 15°, a 15° increase in femoral anteversion caused JRFs to be less posterior in early stance (Δ = 0.43 ± 0.22 xbodyweight) and more anterior in late stance (Δ = 0.60 ± 14 xbodyweight). Relative retroversion caused anteroposterior changes that were similar to anteversion in early stance but opposite in late stance. Resultant JRFs experienced the largest changes during late stance where anteversion raised the peak by 0.48 ± 0.15 xbodyweight and relative retroversion lowered the peak by 0.32 ± 0.30 xbodyweight. Increasing anteversion increased hip flexor and abductor muscle forces, which caused the changes in JRFs. Identifying how FV deformities influence hip joint loading can elucidate their role in the mechanisms of hip degeneration in patients with DDH., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Background: Developmental dysplasia of the hip is characterized by abnormal acetabular and femoral geometries that alter joint loading and increase the risk of hip osteoarthritis. Current understanding of biomechanics in this population remains isolated to the hip and largely focused on level-ground walking, which may not capture the variable loading conditions that contribute to symptoms and intra-articular damage., Methods: Thirty young adult females (15 with dysplasia) underwent gait analysis during level, 10° incline, and 10° decline walking while whole-body kinematics, ground reaction forces, and electromyography (EMG) were recorded. Low back, hip, and knee joint kinematics and internal joint moments were calculated using a 15-segment model and integrated EMG was calculated within the functional phases of gait. Dependent variables (peak joint kinematics, moments, and integrated EMG) were compared across groups with a one-way ANOVA with multiple comparisons controlled for using the Benjamini-Hochberg method (α = 0.05)., Findings: During level and incline walking, patients with developmental dysplasia of the hip had significantly lower trunk flexion angles, lumbar and knee extensor moments, and erector spinae activity than controls. Patients with developmental dysplasia of the hip also demonstrated reduced rectus femoris activity during loading of level walking and increased gluteus maximus activity during mid-stance of decline walking., Interpretation: Patients with developmental dysplasia of the hip adopt compensations both proximal and distal to the hip, which vary depending on the slope of walking. Furthering the understanding of multi-joint biomechanical compensations is important for understanding the mechanism of osteoarthritis development as well as secondary conditions., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Rehabilitation for patients with developmental dysplasia of the hip (DDH) addresses modifiable factors in an effort to reduce symptoms and prevent or delay the development of osteoarthritis, yet its effect on joint mechanics remains unknown. Our objective was to establish how rehabilitation (muscle strengthening and movement training), simulated with a musculoskeletal model and probabilistic analyses, alters hip joint reaction forces (JRF) in patients with DDH during a single limb squat. In four patients with DDH, hip abductor strengthening was simulated by increasing the maximum isometric force value between 0 and 32.6% and movement training was simulated by decreasing the hip adduction angle between 0 and 10° relative to baseline. 2,000 Monte Carlo simulations were performed separately to simulate strengthening and movement training, from which 99% confidence bounds and sensitivity factors were calculated. Our results indicated that simulated movement training aimed at decreasing hip adduction had a substantially larger influence on hip JRF than strengthening, as indicated by 99% confidence bounds of the resultant JRF (0.88 ± 0.55 xBW vs. 0.31 ± 0.12 xBW, respectively). Relative to baseline, movement training that resulted in a 10° decrease in hip adduction decreased the resultant JRF by 0.78 ± 0.65 xBW, while strengthening the abductors by 17.6% increased resultant JRF by 0.18 ± 0.06 xBW. To our knowledge, these results are the first to provide evidence pertaining to the effect of rehabilitation on joint mechanics in patients with DDH and can be used to inform more targeted interventions., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Developmental dysplasia of the hip (DDH) is characterized by abnormal bony anatomy, which causes detrimental hip joint loading and leads to secondary osteoarthritis. Hip joint loading depends, in part, on muscle-induced joint reaction forces (JRFs), and therefore, is influenced by hip muscle moment arm lengths (MALs) and lines of action (LoAs). The current study used subject-specific musculoskeletal models and in-vivo motion analysis to quantify the effects of DDH bony anatomy on dynamic muscle MALs, LoAs, and their contributions to JRF peaks during early (~17%) and late-stance (~52%) of gait. Compared to healthy hips (N = 15, 16-39 y/o), the abductor muscles in patients with untreated DDH (N = 15, 16-39 y/o) had smaller abduction MALs (e.g. anterior gluteus medius, 35.3 vs. 41.6 mm in early stance, 45.4 vs. 52.6 mm late stance, p ≤ 0.01) and more medially-directed LoAs. Abduction-adduction and rotation MALs also differed for major hip flexors such as rectus femoris and iliacus. The altered MALs in DDH corresponded to higher hip abductor forces, medial JRFs (1.26 vs. 0.87 × BW early stance, p = 0.03), and resultant JRFs (5.71 vs. 4.97 × BW late stance, p = 0.05). DDH anatomy not only affected hip muscle force generation in the primary plane of function, but also their out-of-plane mechanics, which collectively elevated JRFs. Overall, hip muscle MALs and their contributions to JRFs were significantly altered by DDH bony anatomy. Therefore, to better understand the mechanisms of joint degeneration and improve the efficacy of treatments for DDH, the dynamic anatomy-force relationships and multi-planar functions of the whole hip musculature must be collectively considered., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Acetabular dysplasia is primarily characterized by an altered acetabular geometry that results in deficient coverage of the femoral head, and is a known cause of hip osteoarthritis. Periacetabular osteotomy (PAO) is a surgical reorientation of the acetabulum to normalize coverage, yet its effect on joint loading is unknown. Our objective was to establish how PAO, simulated with a musculoskeletal model and probabilistic analysis, alters hip joint reaction forces (JRF) in two representative patients of two different acetabular dysplasia subgroups: anterolateral and posterolateral coverage deficiencies. PAO reorientation was simulated within the musculoskeletal model by adding three surgical degrees of freedom to the acetabulum relative to the pelvis (acetabular adduction, acetabular extension, medial translation of the hip joint center). Monte Carlo simulations were performed to generate 2000 unique PAO reorientations for each patient; from which 99% confidence bounds and sensitivity factors were calculated to assess the influence of input variability (PAO reorientation) on output (hip JRF) during gait. Our results indicate that reorientation of the acetabulum alters the lines of action of the hip musculature. Specifically, as the hip joint center was medialized, the moment arm of the hip abductor muscles was increased, which in turn increased the mechanical force-generating capacity of these muscles and decreased joint loading. Independent of subgroup, hip JRF was most sensitive to hip joint center medialization. Results from this study improve understanding of how PAO reorientation affects muscle function differently dependent upon acetabular dysplasia subgrouping and can be used to inform more targeted surgical interventions., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Although increasing evidence suggests that abnormal femur geometry in developmental dysplasia of the hip (DDH) may contribute to intra-articular damage and the development of hip osteoarthritis, a comprehensive 3D description of femoral abnormalities in DDH remains incomplete. Statistical shape modeling (SSM) was used to quantify three-dimensional (3D) geometric variation among femurs in female patients with DDH and control subjects. SSM correspondence points (n = 8,192) were placed on each femur using a gradient descent energy function to derive mean DDH and control femoral shapes and principal component analysis (PCA) was then used to describe shape variation. PCA results were associated with common 2D radiographic measures of femur shape using general linear models. For patients with DDH, the first eight principal components (modes) captured 90.9% of the cumulative variance accounted for (VAF). Notably, mode 2 captured 23.6% VAF and described variation in femoral version, the neck-shaft angle, and femoral neck length, while mode 3 captured 16.4% VAF and described variation in femoral version, femoral head size, and femoral offset. SSM captured complex geometric deformities in DDH, which may not be fully described by 2D measures of the acetabulum and proximal femur alone. By determining the primary shape variations among femurs in cases of DDH, SSM may further understanding of pathologies on the femoral side of dysplastic hips, in context with more commonly recognized acetabular deformities. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res., (© 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.)

The objective of this investigation was to identify demands from core muscles that corresponded with trunk movement compensations during bilateral step ambulation in people with unilateral transtibial amputation (TTA). Trunk rotational angular momentum (RAM) was measured using motion capture and bilateral surface EMG was measured from four bilateral core muscles during step ascent and descent tasks in people with TTA and healthy controls. During step ascent, the TTA group generated larger mediolateral (P = 0.01) and axial (P = 0.01) trunk RAM toward the leading limb when stepping onto the intact limb than the control group, which corresponded with high demand from the bilateral erector spinae and oblique muscles. During step descent, the TTA group generated larger trunk RAM in the sagittal (P < 0.01), frontal (P < 0.01), and transverse planes (P = 0.01) than the control group, which was an effect of falling onto the intact limb. To maintain balance and arrest trunk RAM, core muscle demand was larger throughout the loading period of step descent in the TTA group. However, asymmetric trunk movement compensations did not correspond to asymmetric core muscle demand during either task, indicating a difference in motor control compensations dependent on the leading limb., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Background: Patients with transtibial amputation adopt trunk movement compensations that alter effort and increase the risk of developing low back pain. However, the effort required to achieve high-demand tasks, such as step ascent and descent, remains unknown., Methods: Kinematics were collected during bilateral step ascent and descent tasks from two groups: 1) seven patients with unilateral transtibial amputation and 2) seven healthy control subjects. Trunk kinetic effort was quantified using translational and rotational segmental moments (time rate of change of segmental angular momentum). Peak moments during the loading period were compared across limbs and across groups., Findings: During step ascent, patients with transtibial amputation generated larger sagittal trunk translational moments when leading with the amputated limb compared to the intact limb (P=0.01). The amputation group also generated larger trunk rotational moments in the frontal and transverse planes when leading with either limb compared to the healthy group (P=0.01, P<0.01, respectively). During step descent, the amputation group generated larger trunk translational and rotational moments in all three planes when leading with the intact limb compared to the healthy group (P<0.017)., Interpretation: This investigation identifies how differing trunk movement compensations, identified using the separation of angular momentum, require higher kinetic effort during stepping tasks in patients with transtibial amputation compared to healthy individuals. Compensations that produce identified increased and asymmetric trunk segmental moments, may increase the risk of the development of low back pain in patients with amputation., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Joint kinetic measurement is a fundamental tool used to quantify compensatory movement patterns in participants with transtibial amputation (TTA). Joint kinetics are calculated through inverse dynamics (ID) and depend on segment kinematics, external forces, and both segment and prosthetic inertial parameters (PIPS); yet the individual influence of PIPs on ID is unknown. The objective of this investigation was to assess the importance of parameterizing PIPs when calculating ID using a probabilistic analysis. A series of Monte Carlo simulations were performed to assess the influence of uncertainty in PIPs on ID. Multivariate input distributions were generated from experimentally measured PIPs (foot/shank: mass, center of mass (COM), moment of inertia) of ten prostheses and output distributions were hip and knee joint kinetics. Confidence bounds (2.5-97.5%) and sensitivity of outputs to model input parameters were calculated throughout one gait cycle. Results demonstrated that PIPs had a larger influence on joint kinetics during the swing period than the stance period (e.g., maximum hip flexion/extension moment confidence bound size: stance = 5.6 N·m, swing: 11.4 N·m). Joint kinetics were most sensitive to shank mass during both the stance and swing periods. Accurate measurement of prosthesis shank mass is necessary to calculate joint kinetics with ID in participants with TTA with passive prostheses consisting of total contact carbon fiber sockets and dynamic elastic response feet during walking., (Copyright © 2017 by ASME.)