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Background: A hip flexion contracture (HFC) results in an inability to extend the hip by reducing the ROM of the affected hip. The condition affects one in four patients with above-knee amputations on the amputation side. While HFC in other disorders is known to decrease hip ROM and increase pelvic tilt during gait, its impact on the gait of patients with above-knee amputations remains unexplored. Typically, prosthetists design the socket with a flexion angle matching the HFC, potentially leading to compensations during the posterior stance phase of the gait cycle. To our knowledge, little is known about how or whether these compensations relate to the socket's flexion alignment., Questions/purposes: (1) Is the presence of HFC associated with modifications of spatiotemporal and kinematic parameters during gait in patients with an above-knee amputation? (2) Is there a correlation between the socket flexion angle and the spatiotemporal and kinematic parameters during gait in patients with an above-knee amputation with and without HFC?, Methods: A comparative observational study was conducted between February 2022 and June 2023. Thirty-two participants with unilateral above-knee amputations who had undergone amputation at least 1 year prior and had a minimum of 1 month of experience with their current prostheses were eligible for consideration and included in the study. After the trial, 1 of 32 participants was excluded due to other impairments affecting gait, and 9% (3 of 32) were excluded because of pain or discomfort during data acquisition on their gait, leaving 88% (28 of 32) of participants included in the analysis. The median (IQR) age of participants in the HFC group (n = 13) was 50 years (26 to 56); 85% (11) were male and 15% (2) were female. The median (IQR) age of participants in the noHFC group (n = 15) was 41 years (32 to 56), and 100% were male. Time since amputation was similar between groups (HFC median 8 years [IQR 3 to 21], noHFC median 6 years [IQR 1 to 9], difference of medians 2; p = 0.31). Thirty-two percent (9 of 28) of patients were classified according to the Medicare Functional Classification Level system as K4 (exceeding basic ambulation skills) and 68% (19 of 28) were classified as K3 (ability to walk with variable cadence and traverse most environmental barriers). Clinical and prosthetic measurements were made, which comprised measurement of the HFC using a hand-held goniometer with the patient in the modified Thomas test position, the socket flexion alignment, and the difference (δ) between the HFC and socket flexion alignment. A gait analysis was performed with an optoelectronic system equipped with six infrared cameras and two force plates to analyze the time-distance and kinematic parameters of gait. To answer our first question, we quantitively compared the gait spatiotemporal and kinematic parameters between groups, and for the second question, we evaluated the correlations between the same parameters and prosthesis alignment for both groups., Results: During gait, the HFC group exhibited reduced mean ± SD residual hip ROM in comparison with the noHFC group (35° ± 6° versus 44° ± 6°, mean difference -9° [95% CI -13° to -6°]; p < 0.001), increased pelvic tilt (11° ± 6° versus 7° ± 3°, mean difference 4° [95% CI 1° to 8°]; p = 0.02), increased pelvic rotation (12° ± 3° versus 9° ± 2°, mean difference 3° [95% CI 2° to 6°]; p < 0.001), and increased trunk rotation (15° ± 5° and 12° ± 2°, mean difference 3° [95% CI 0° to 6°]; p = 0.04). Greater δ correlated with decreased ROM in the contralateral hip (r = -0.71; p = 0.006), pelvis (r = -0.77; p = 0.002), and trunk (r = -0.58; p = 0.04) in the sagittal plane and with increased residual hip ROM (r = 0.62; p = 0.02). In terms of spatiotemporal gait parameters, in the HFC group, the δ correlated with an increase in contralateral step width (r = 0.58; p = 0.04) and a decrease in prosthetic step length (r = -0.65; p = 0.02)., Conclusion: Our findings further suggest that physiotherapists should consider the pelvic and trunk compensations associated with HFC in their rehabilitation because of potential long-term effects, such as low back pain or osteoarthritis. In addition, the correlation between the socket flexion angle and the parameters involved may support prosthetists in their choices of prosthetic settings. For now, we cannot consider these compensations as an impaired gait syndrome, and future studies are needed to evaluate their impact on patients' quality of life., Level of Evidence: Level III, therapeutic study., Competing Interests: Each author certifies that there are no funding or commercial associations (consultancies, stock ownership, equity interest, patent/licensing arrangements, etc.) that might pose a conflict of interest in connection with the submitted article related to the author or any immediate family members. All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research® editors and board members are on file with the publication and can be viewed on request., (Copyright © 2024 by the Association of Bone and Joint Surgeons.)

Maintaining forward walking during human locomotion requires mechanical joint work, mainly provided by the ankle-foot in non-amputees. In lower-limb amputees, their metabolic overconsumption is generally attributed to reduced propulsion. However, it remains unclear how altered walking patterns resulting from amputation affect energy exchange. The purpose of this retrospective study was to investigate the impact of self-selected walking speed (SSWS) on mechanical works generated by the ankle-foot and by the entire lower limbs depending on the level of amputation. 155 participants, including 47 non-amputees (NAs), 40 unilateral transtibial amputees (TTs) and 68 unilateral transfemoral amputees (TFs), walked at their SSWS. Positive push-off work done by the trailing limb (W StS + ) and its associated ankle-foot (W ankle-foot + ), as well as negative collision work done by the leading limb (W StS - ) were analysed during the transition from prosthetic limb to contralateral limb. An ANCOVA was performed to assess the effect of amputation level on mechanical works, while controlling for SSWS effect. After adjusting for SSWS, NAs produce more push-off work with both their biological ankle-foot and trailing limb than amputees do on prosthetic side. Using the same type of prosthetic feet, TTs and TFs can generate the same amount of prosthetic W ankle-foot + , while prosthetic W StS + is significantly higher for TTs and remains constant with SSWS for TFs. Surprisingly and contrary to theoretical expectations, the lack of propulsion at TFs' prosthetic limb did not affect their contralateral W StS - , for which a difference is significant only between NAs and TTs. Further studies should investigate the relationship between the TFs' inability to increase prosthetic limb push-off work and metabolic expenditure., 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 © 2024 Elsevier Ltd. All rights reserved.)

In vivo characterization of intervertebral disc (IVD) mechanical properties and microstructure could give an insight into the onset and progression of disc pathologies. Ultrasound shearwave elastography provided promising results in children, but feasibility in adult lumbar discs, which are deep in the abdomen, was never proved. The aim of this work was to determine the feasibility and reliability of ultrasound assessment of lumbar IVD in adults. Thirty asymptomatic adults were included (22 to 67 years old). Subjects were lying supine, and the annulus fibrosus of the L3-L4 IVD was imaged by conventional ultrasonography and shearwave elastography. Shear wave speed (SWS) and lamellar thickness were measured. Reliability was determined through repeated measurements acquired by three operators. Average SWS in AF at the L3L4 level was 4.0 ± 0.9 m/s, with an inter-operator uncertainty of 8.7%, while lamellar thickness was 255 ± 27 µm with an uncertainty of 9.6%. Measurement was not feasible in one out of four subjects with BMI > 24 kg/m² (overweight). Ultrasound assessment of annulus fibrosus revealed feasible, within certain limitations, and reproducible. This method gives an insight into disc microstructure and mechanical properties, and it could be applied for the early detection or follow-up of disc pathologies., Competing Interests: Declaration of Competing Interest No conflict of interest to disclose., (Copyright © 2023 IPEM. Published by Elsevier Ltd. All rights reserved.)

Objective: This study aimed to evaluate the long-term stability of surgical maxillary expansion using patient-specific fixation implants (PSFIs) without intraoral retention., Materials and Methods: Fifteen patients who had undergone segmented Le Fort I osteotomy and PSFIs with available preoperative (t0) early (t1) and 1-year follow-up computed tomography (CT) scans (t2) were evaluated. The early and 1-year 3D models were superimposed to transfer the bony landmarks; the distances between each pair of landmarks at the different time points were then measured. The distances between the canines and second molars were also measured directly on the CT scans., Results: The achieved maxillary expansions ranged from a median of 4.39 (2.00-6.27) mm at the greater palatine foramina to a median of 2.14 (1.56-2 > 83) mm at the canine level of the palatal bone. One year postoperatively, the changes in skeletal diameters ranged from a median of - 0.53 (- 1.65 to 0.41) mm at the greater palatine foramina (p = 0.12) to 0.17 (- 0.09 to 0.32) mm at the canine level of the palatal bone (p = 0.56). Changes in dental arch diameters ranged from a median of - 0.6 (- 2 to 0.00) mm between the second molars to - 1.3 (- 1.8 to - 0.25) mm between the canines (P < 0.05)., Conclusion: This study showed the stability of maxillary expansion osteotomy using PSFIs, even without postoperative intraoral retention., Clinical Relevance: PSFIs are a reliable method for the surgical treatment of transverse maxillary discrepancy. PFSIs are easy-to-use and improve surgical accuracy., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Maxillomandibular deformity (MMD) and body posture appear to be correlated. However, no systematic literature review of the available evidence to support this correlation has been performed to date. The aim of this study was to conduct a systematic literature review on posture and MMD. This systematic literature review was registered in the PROSPERO database. Systematic searches of the MEDLINE, Scopus, Cochrane Library, and Web of Science databases were performed. In total, 13 clinical studies were included. Nine found a significant association between MMD and body posture or body balance: two studies showed a correlation between increased cervical lordosis and skeletal class III MMD, two studies showed an interaction between mandibular deviation and scoliosis, four studies demonstrated a significant association between lumbar column and pelvis anatomy and MMD, and one study found a correlation between displacement of the centre of mass and MMD. However, the level of evidence is low; the methods used to evaluate body posture and MMD were inconsistent. Orthognathic surgery could modify body posture. Although there seems to be an interaction between body posture and facial deformity, the number of studies is too small and the level of evidence too low to strongly support this association., (Copyright © 2021 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.)

Persons with above-knee amputation have increased energy consumption and greater difficulty in negotiating uphill and downhill slopes. Walking on slopes requires an adaptation of the positive and negative work performed by the joints of the lower limb to propel the center of mass. Modern prosthetic feet and knees can only partially adapt to changes in inclination, and the redistribution of joint work among persons with above-knee amputation is not described in the literature. Level, upslope and downslope walking (at 5% and 12% inclinations) were investigated for twelve subjects with transfemoral amputation fitted with an Energy Storing And Return foot (ESAR) and a Microprocessor controlled Prosthetic Knee (MPK) versus a control group of seventeen asymptomatic subjects. Lower limb joint and individual limb power and work were compared between prosthetic, contralateral and control limbs. The prosthesis dissipates less energy than the joints of the lower limb of the control group when descending the slope, but the demand on the contralateral limb is limited by a lower speed and step length. The huge deficit of positive work produced by the prosthetic ankle cannot be compensated by the residual hip during level and slope ascent which transfers the demand for energy production to the contralateral limb up to 40% on a 12% slope. This study highlights that prosthetic devices (ESAR foot and MPK) for persons with above-knee amputation present some limitations during slope walking that cannot be compensated by the residual hip and increase the work performed by the contralateral limb., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Subject-specific tensioning of ligaments is essential for the stability of the knee joint and represents a challenging aspect in the development of finite element models. We aimed to introduce and evaluate a new procedure for the quantification of ligament prestrains from biplanar X-ray and CT data. Subject-specific model evaluation was performed by comparing predicted femorotibial kinematics with the in vitro response of six cadaveric specimens. The differences obtained using personalized models were comparable to those reported in similar studies in the literature. This study is the first step toward the use of simplified, personalized knee FE models in clinical context such as ligament balancing.

Skin Marker (SM) based motion capture is the most widespread technique used for motion analysis. Yet, the accuracy is often hindered by Soft Tissue Artifact (STA). This is a major issue in clinical gait analysis where kinematic results are used for decision-making. It also has a considerable influence on the results of rigid body and Finite Element (FE) musculoskeletal models that rely on SM-based kinematics to estimate muscle, contact and ligament forces. Current techniques devised to compensate for STA, in particular multi-body optimization methods, often consider simplified joint models. Although joint personalization with anatomical constraints has improved kinematic estimation, these models yet don't represent a fully reliable solution to the STA problem, thus allowing us to envisage an alternative approach. In this perspective, we propose to develop a conceptual FE-based model of the lower limb for STA compensation and evaluate it for 66 healthy subjects under level walking motor task. Both hip and knee joint kinematics were analyzed, considering both rotational and translational joint motion. Results showed that STA caused underestimation of the hip joint kinematics (up to 2.2°) for all rotational DoF, and overestimation of knee joint kinematics (up to 12°) except in flexion/extension. Joint kinematics, in particular the knee joint, appeared to be sensitive to soft tissue stiffness parameters (rotational and translational mean difference up to 1.5° and 3.4 mm). Analysis of the results using alternative joint representations highlighted the versatility of the proposed modeling approach. This work paves the way for using personalized models to compensate for STA in healthy subjects and different activities., 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 © 2021 Elsevier Ltd. All rights reserved.)