Publications by authors named "Amy L Lenz"

Background: Tibiotalar arthrodesis and total ankle replacement are current standards for treating end-stage ankle osteoarthritis. Our clinical understanding of biomechanical causes and risk factors for subtalar secondary osteoarthritis development following surgical treatment is limited. The objective of this retrospective study was to investigate subchondral bone morphometric differences of individuals treated with a tibiotalar arthrodesis or ankle arthroplasty that may influence subtalar joint measurements during overground walking; results were compared between surgical groups, their unaffected limb, and asymptomatic controls.

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Background: Charcot-Marie-Tooth disease (CMT), a common inherited neurologic disorder, significantly impacts the morphology of foot bones, particularly the talus. The disease has been classified into types based on specific mutations, with the most common being CMT type 1 (CMT1; demyelinating) and CMT type 2 (CMT2; axonal). However, the specific osseous morphologic variations in CMT patients and their major genetic subgroups remain insufficiently understood, posing challenges in clinical management and surgical intervention.

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Increasing utilization of weight-bearing computed tomography and fluoroscopy has driven the need for standardization of 3 dimensional (3D) measurements in the foot and ankle. These emerging imaging modalities are currently used to evaluate foot and ankle conditions including ankle osteoarthritis, progressive collapsing foot deformity, midfoot instability, and hallux valgus. This study aims first to provide a comprehensive review of clinical studies that have utilized these 3D methodologies.

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This study aimed to validate the use of weightbearing computed tomography against conventional computed tomography and against bead tracking for markerless tracking of key foot and ankle bones. A left cadaveric limb was implanted with tantalum beads and underwent conventional computed tomography and weightbearing computed tomography scanning, followed by biplane fluoroscopy motion capture to simulate gait. Bone models from conventional computed tomography and weightbearing computed tomography were compared for surface differences and kinematic analysis across six joints.

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The ankle infrequently develops primary osteoarthritis (OA), especially when compared to the hip and the knee. Ankle OA instead generally develops only after trauma. The consequences of end-stage ankle OA can nonetheless be extremely debilitating, with impairment comparable to that of end-stage kidney disease or congestive heart failure.

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Article Synopsis
  • - The study investigates advancements in foot and ankle biomechanics using new technologies like biplane fluoroscopy and weightbearing CT to assess motion and structure under realistic conditions.
  • - Researchers highlight the importance of standardized 3D coordinate systems for accurately analyzing foot and ankle alignment, noting that variations across studies can lead to inconsistent data.
  • - The impact of different foot deformities on coordinate systems was evaluated in four patient groups, suggesting that automated systems aligning with clinical anatomy are preferred for accurate assessment over principal component axes, which may not correspond to relevant anatomical planes.
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Article Synopsis
  • * By testing ten pairs of human cadaveric feet, researchers found that while both arches affect the collapse of the longitudinal arch and forefoot abduction, the MLA has a stronger influence compared to the TTA.
  • * The results highlight that although weakness in the TTA significantly impacts certain aspects of PCFD, it doesn't surpass the influence of the MLA, which may inform better treatment approaches for flatfoot conditions.
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Accurate anatomical coordinate systems for the foot and ankle are critical for interpreting their complex biomechanics. The tibial superior-inferior axis is crucial for analyzing joint kinematics, influencing bone motion analysis during gait using CT imaging and biplane fluoroscopy. However, the lack of consensus on how to define the tibial axis has led to variability in research, hindering generalizability.

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Background: Advanced varus ankle osteoarthritis is a debilitating disease that can present with limited physical function, severe pain, and diminished quality of life. Weightbearing computed tomography enables submillimeter 3-dimensional visualization, computational analyses, and enhanced diagnoses in reporting complex degenerative changes more accurately.

Research Question: This study set to compare static posture weightbearing joint angle differences in healthy and varus ankle osteoarthritis patients (compensated and non-compensated).

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Purpose Of Review: Musculoskeletal imaging serves a critical role in clinical care and orthopaedic research. Image-based modeling is also gaining traction as a useful tool in understanding skeletal morphology and mechanics. However, there are fewer studies on advanced imaging and modeling in pediatric populations.

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Accurate analysis of bone position and orientation in foot and ankle studies relies on anatomical coordinate systems (ACS). Reliable ACSs are necessary for many biomechanical and clinical studies, especially those including weightbearing computed tomography and biplane fluoroscopy. Existing ACS approaches suffer from limitations such as manual input, oversimplifications, or non-physiological methods.

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Tarsometatarsal joint arthrodesis is used to treat a variety of injuries and deformities in the midfoot. However, the surgical technique has not been optimized, in part due to limited knowledge of morphologic features and variation in the related joints. Previous research has relied primarily on dissection-based anatomical analysis, but quantitative imaging may allow for a more sophisticated description of this complex.

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Progressive collapsing foot deformity (PCFD) is characterized by a progressive subluxation of the peritalar bones and respective joints. Two-dimensional conventional radiographs are limited in their ability to visualize the peritalar bones and joints with adequate detail to describe the complex three-dimensional deformity. An improved understanding of the relationship between joint coverage and deformity would allow clinicians to use coverage analysis to distinguish among the stages of PCFD.

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Statistical shape modeling is an indispensable tool in the quantitative analysis of anatomies. Particle-based shape modeling (PSM) is a state-of-the-art approach that enables the learning of population-level shape representation from medical imaging data (e.g.

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Advancements in volumetric imaging makes it possible to generate high-resolution three-dimensional reconstructions of bones in throughout the foot and ankle. The use of weightbearing computed tomography allows for the analysis of joint relationships in a consistent natural position that can be used for statistical shape modeling. Using statistical shape modeling, a population-based statistical model is created that can be used to compare mean bone shape morphology and identify anatomical modes of variation.

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Femoroacetabular impingement syndrome (FAIS) is a motion-related pathology of the hip characterized by pain, morphological abnormalities of the proximal femur, and an elevated risk of joint deterioration and hip osteoarthritis. Activities that require deep flexion are understood to induce impingement in cam FAIS patients, however, less demanding activities such as walking and pivoting may induce pain as well as alterations in kinematics and joint stability. Still, the paucity of quantitative descriptions of cam FAIS has hindered understanding underlying hip joint mechanics during such activities.

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Traditionally, two-dimensional conventional radiographs have been the primary tool to measure the complex morphology of the foot and ankle. However, the subtalar, talonavicular, and calcaneocuboid joints are challenging to assess due to their bone morphology and locations within the ankle. Weightbearing computed tomography is a novel high-resolution volumetric imaging mechanism that allows detailed generation of 3D bone reconstructions.

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Much of our current understanding of age-related declines in mobility has been aided by decades of investigations on the role of muscle-tendon units spanning major lower extremity joints (e.g., hip, knee and ankle) for powering locomotion.

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Background: There is no consensus surgical treatment algorithm for talar body fractures, with authors recommending both soft tissue-only and osteotomy-based approaches. This study evaluates talar dome access via dual approaches to the talar dome through anterolateral transligamentous (ATL) and modified posteromedial (mPM) approaches.

Methods: Ten cadaveric legs (5 matched pairs) were included.

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Objectives: Compare accessible area of the posterior tibial plateau through a modified posteromedial (PM) approach before and after tenotomy of the medial head gastrocnemius. We report the outcomes of 8 patients who underwent gastrocnemius tenotomy during PM approach.

Methods: A modified PM approach was performed on 10 cadaveric legs, and the surgically accessible area was outlined.

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Cam-type femoroacetabular impingement (FAI) syndrome is a painful, structural hip disorder. Herein, we investigated hip joint mechanics through in vivo, dynamic measurement of the bone-to-bone distance between the femoral head and acetabulum in patients with cam FAI syndrome and morphologically screened controls. We hypothesized that individuals with cam FAI syndrome would have larger changes in bone-to-bone distance compared to the control group, which we would interpret as altered joint mechanics as signified by greater movement of the femoral head as it articulates within the acetabulum.

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Background: In vivo measurements of tibiotalar and subtalar joint motion following TAR are unavailable. Using biplane fluoroscopy, we tested the hypothesis that the prosthetic tibiotalar joint and adjacent subtalar joint would demonstrate kinematic and range of motion differences compared to the contralateral untreated limb, and control participants.

Methods: Six patients of 41 identified candidates that all underwent unilateral Zimmer TAR (5.

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Injuries to the Lisfranc complex may require surgical fixation, the stability of which may be correlated with bone mineral density (BMD). However, there is limited research on regional BMD variations in the Lisfranc complex. This study used quantitative micro-CT to characterize regional BMD in the four bones (medial cuneiform, intermediate cuneiform, first metatarsal, and second metatarsal) of this complex.

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Background: Posterior talar body fractures are rare injuries without a consensus surgical approach. This study evaluates the accessible area of the talar dome through 2 posteromedial approach intervals (posteromedial [PM] and modified posteromedial [mPM]) both with and without distraction.

Methods: Ten male cadaveric legs (5 matched pairs) were included.

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Despite decades of research since its first description, subtalar joint instability remains a diagnostic enigma within the concept of hindfoot instability. This could be attributed to current imaging techniques, which are impeded by two-dimensional measurements. Therefore, we used weightbearing computed tomography imaging to quantify three-dimensional displacement associated with subtalar joint instability.

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