Scholars@Duke
Louis Edwin DeFrate

Louis Edwin DeFrate

Laszlo Ormandy Distinguished Professor of Orthopaedic Surgery
Orthopaedic Surgery
lou.defrate@duke.edu
MSRB Room 379, Box 3093 DUMC, Durham, NC 27710
Room 379, Medical Sciences Research Building, Box 3093 Med. Ctr., Durham, NC 27710

Scholarly Works - Journal articles

The application of transfer learning to T1ρ MRI tibiofemoral cartilage segmentation.

Journal article J Biomech · January 2026 Proteoglycans are critical to the ability of cartilage to withstand loading, and their concentration can be probed in vivo through measurement of T1ρ MRI relaxation times. Machine learning models have demonstrated the potential to replace manual segmentati ... Full text Link to item Cite

A deep learning-based approach for measuring patellar cartilage deformations from knee MR images.

Journal article J Biomech · November 2025 While knee osteoarthritis (OA) is a leading cause of disability in the United States, OA within the patellofemoral joint is understudied compared to the tibiofemoral joint. Mechanical alterations to cartilage may be among the first changes indicative of ea ... Full text Link to item Cite

Resting Supine for 45 Minutes Yields Consistent Baseline Lumbar Intervertebral Disc Height in Asymptomatic Participants.

Journal article Ann Biomed Eng · August 2025 PURPOSE: Intervertebral disc (IVD) height fluctuates diurnally as the spine is exposed to periods of high and low loading. Therefore, accounting for loading history prior to measuring in vivo IVD height is important when investigating IVD mechanics. Howeve ... Full text Link to item Cite

Tibiofemoral cartilage strain and recovery following a 3-mile run measured using deep learning segmentation of bone and cartilage.

Journal article Osteoarthr Cartil Open · March 2025 OBJECTIVE: We sought to measure the deformation of tibiofemoral cartilage immediately following a 3-mile treadmill run, as well as the recovery of cartilage thickness the following day. To enable these measurements, we developed and validated deep learning ... Full text Link to item Cite

Does Tibial Plateau Slope and Depth Influence ACL Strain In Vivo?

Journal article Orthop J Sports Med · December 2024 BACKGROUND: The anterior cruciate ligament (ACL) is loaded under tension when the tibia translates anteriorly relative to the femur. The shape of the articular surfaces of the tibiofemoral joint may influence the amount of anterior tibial translation under ... Full text Link to item Cite

A comparison of three methods for establishing an ACL reference length in vivo.

Journal article J Biomech · November 2024 As anterior cruciate ligament (ACL) injuries are highly prevalent among active individuals, it is vital to better understand the loading conditions which lead to injury. One method for doing so is through measurement of dynamic, in vivo ACL strain. To meas ... Full text Link to item Cite

High angular resolution diffusion imaging (HARDI) of porcine menisci: a comparison of diffusion tensor imaging and generalized q-sampling imaging.

Journal article Quant Imaging Med Surg · April 3, 2024 BACKGROUND: Diffusion magnetic resonance imaging (MRI) allows for the quantification of water diffusion properties in soft tissues. The goal of this study was to characterize the 3D collagen fiber network in the porcine meniscus using high angular resoluti ... Full text Link to item Cite

Influence of running on femoroacetabular joint bone-to-bone distances.

Journal article Journal of orthopaedic research : official publication of the Orthopaedic Research Society · April 2024 There is limited data quantifying the influence of running on hip cartilage mechanics. The goal of this investigation was to quantify changes in hip joint bone-to-bone distance in response to a 3-mile treadmill run. We acquired magnetic resonance (MR) imag ... Full text Cite

The effects of a 6-month weight loss intervention on physical function and serum biomarkers in older adults with and without osteoarthritis.

Journal article Osteoarthr Cartil Open · September 2023 OBJECTIVE: To examine the effects of a 6-month weight loss intervention on physical function, inflammatory biomarkers, and metabolic biomarkers in both those with and without osteoarthritis (OA). DESIGN: 59 individuals ≥60 years old with obesity and a func ... Full text Link to item Cite

Automated segmentation and prediction of intervertebral disc morphology and uniaxial deformations from MRI.

Journal article Osteoarthr Cartil Open · September 2023 OBJECTIVE: The measurement of in vivo intervertebral disc (IVD) mechanics may be used to understand the etiology of IVD degeneration and low back pain (LBP). To this end, our lab has developed methods to measure IVD morphology and uniaxial compressive defo ... Full text Link to item Cite

Auto-segmentation of the tibia and femur from knee MR images via deep learning and its application to cartilage strain and recovery.

Journal article J Biomech · March 2023 The ability to efficiently and reproducibly generate subject-specific 3D models of bone and soft tissue is important to many areas of musculoskeletal research. However, methodologies requiring such models have largely been limited by lengthy manual segment ... Full text Link to item Cite

The Interplay of Biomechanical and Biological Changes Following Meniscus Injury.

Journal article Curr Rheumatol Rep · February 2023 PURPOSE OF REVIEW: Meniscus injury often leads to joint degeneration and post-traumatic osteoarthritis (PTOA) development. Therefore, the purpose of this review is to outline the current understanding of biomechanical and biological repercussions following ... Full text Link to item Cite

Elevated In Vivo ACL Strain Is Associated With a Straight Knee in Both the Sagittal and the Coronal Planes.

Journal article Am J Sports Med · February 2023 BACKGROUND: Noncontact anterior cruciate ligament (ACL) injuries typically occur during deceleration movements such as landing or cutting. However, conflicting data have left the kinematic mechanisms leading to these injuries unclear. Quantifying the influ ... Full text Link to item Cite

In vivo intervertebral disc mechanical deformation following a treadmill walking "stress test" is inversely related to T1rho relaxation time.

Journal article Osteoarthritis Cartilage · January 2023 OBJECTIVE: To assess the in vivo relationship between the mechanical response of intervertebral discs (IVDs) to dynamic activity and IVD biochemical composition assessed via T1rho relaxation imaging. DESIGN: Eighteen asymptomatic participants with no histo ... Full text Link to item Cite

The Predicted Position of the Knee Near the Time of ACL Rupture Is Similar Between 2 Commonly Observed Patterns of Bone Bruising on MRI.

Journal article Am J Sports Med · January 2023 BACKGROUND: Bone bruises observed on magnetic resonance imaging (MRI) can provide insight into the mechanisms of noncontact anterior cruciate ligament (ACL) injury. However, it remains unclear whether the position of the knee near the time of injury differ ... Full text Link to item Cite

Predictors of Lumbar Spine Degeneration and Low Back Pain in the Community: The Johnston County Osteoarthritis Project.

Journal article Arthritis Care Res (Hoboken) · October 2022 OBJECTIVE: To determine the incidence and worsening of lumbar spine structure and low back pain (LBP) and whether they are predicted by demographic characteristics or clinical characteristics or appendicular joint osteoarthritis (OA). METHODS: Paired basel ... Full text Link to item Cite

Use of a Novel Multimodal Imaging Technique to Model In Vivo Quadriceps Force and ACL Strain During Dynamic Activity.

Journal article Am J Sports Med · August 2022 BACKGROUND: Quadriceps loading of the anterior cruciate ligament (ACL) may play a role in the noncontact mechanism of ACL injury. Musculoskeletal modeling techniques are used to estimate the intrinsic force of the quadriceps acting at the knee joint. PURPO ... Full text Link to item Cite

In vivo fluid transport in human intervertebral discs varies by spinal level and disc region.

Journal article JOR Spine · June 2022 BACKGROUND: The lumbar discs are large, dense tissues that are primarily avascular, and cells residing in the central region of the disc are up to 6-8 mm from the nearest blood vessel in adults. To maintain homeostasis, disc cells rely on nutrient transpor ... Full text Link to item Cite

Design and validation of a semi-automatic bone segmentation algorithm from MRI to improve research efficiency.

Journal article Sci Rep · May 12, 2022 Segmentation of medical images into different tissue types is essential for many advancements in orthopaedic research; however, manual segmentation techniques can be time- and cost-prohibitive. The purpose of this work was to develop a semi-automatic segme ... Full text Link to item Cite

Lumbar intervertebral disc diurnal deformations and T2 and T1rho relaxation times vary by spinal level and disc region.

Journal article Eur Spine J · March 2022 PURPOSE: Magnetic resonance imaging (MRI) is routinely used to evaluate spine pathology; however, standard imaging findings weakly correlate to low back pain. Abnormal disc mechanical function is implicated as a cause of back pain but is not assessed using ... Full text Open Access Link to item Cite

Obesity impacts the mechanical response and biochemical composition of patellofemoral cartilage: An in vivo, MRI-based investigation.

Journal article J Biomech · March 2022 Obesity is a primary risk factor for osteoarthritis. While previous work has addressed relationships between in vivo cartilage mechanics, composition, and obesity in the tibiofemoral joint, there is limited information on these relationships in the patello ... Full text Link to item Cite

Mechanical metrics may show improved ability to predict osteoarthritis compared to T1rho mapping.

Journal article J Biomech · December 2, 2021 Changes in cartilage structure and composition are commonly observed during the progression of osteoarthritis (OA). Importantly, quantitative magnetic resonance imaging (MRI) methods, such as T1rho relaxation imaging, can noninvasively provide in vivo metr ... Full text Link to item Cite

Diabetes is associated with a lower minimum moment of inertia among older women: An analysis of 3D reconstructions of clinical CT scans.

Journal article J Biomech · November 9, 2021 Hip fractures are a significant burden on the aging population, often resulting in reduced mobility, loss of independence, and elevated risk of mortality. While fracture risk is generally inversely related to bone mineral density (BMD), people with diabete ... Full text Link to item Cite

Immune cell profiles in synovial fluid after anterior cruciate ligament and meniscus injuries.

Journal article Arthritis Res Ther · November 4, 2021 BACKGROUND: Anterior cruciate ligament (ACL) and meniscus tears are common knee injuries. Despite the high rate of post-traumatic osteoarthritis (PTOA) following these injuries, the contributing factors remain unclear. In this study, we characterized the i ... Full text Open Access Link to item Cite

Meniscus cell regional phenotypes: Dedifferentiation and reversal by biomaterial embedding.

Journal article J Orthop Res · October 2021 Meniscus injuries are common and a major cause of long-term joint degeneration and disability. Current treatment options are limited, so novel regenerative therapies or tissue engineering strategies are urgently needed. The development of new therapies is ... Full text Link to item Cite

Increasing BMI increases lumbar intervertebral disc deformation following a treadmill walking stress test.

Journal article J Biomech · May 24, 2021 High body mass index (BMI) and obesity have been implicated as risk factors for lumbar degenerative disc disease and low back pain. Despite this, there is limited in vivo data to quantify how obesity influences the mechanical function of intervertebral dis ... Full text Link to item Cite

Patellar Tendon Orientation and Strain Are Predictors of ACL Strain In Vivo During a Single-Leg Jump.

Journal article Orthop J Sports Med · March 2021 BACKGROUND: There is little in vivo data that describe the relationships between patellar tendon orientation, patellar tendon strain, and anterior cruciate ligament (ACL) strain during dynamic activities. Quantifying how the quadriceps load the ACL via the ... Full text Open Access Link to item Cite

Effect of walking on in vivo tibiofemoral cartilage strain in ACL-deficient versus intact knees.

Journal article J Biomech · February 12, 2021 Anterior cruciate ligament (ACL) rupture alters knee kinematics and contributes to premature development of osteoarthritis. However, there is limited data regarding the in vivo biomechanical response of tibiofemoral cartilage to activities of daily living ... Full text Link to item Cite

Distribution of Bone Contusion Patterns in Acute Noncontact Anterior Cruciate Ligament-Torn Knees.

Journal article Am J Sports Med · February 2021 BACKGROUND: Bone contusions are commonly observed on magnetic resonance imaging (MRI) in individuals who have sustained a noncontact anterior cruciate ligament (ACL) injury. Time from injury to image acquisition affects the ability to visualize these bone ... Full text Link to item Cite

Obesity alters the collagen organization and mechanical properties of murine cartilage.

Journal article Sci Rep · January 15, 2021 Osteoarthritis is a debilitating disease characterized by cartilage degradation and altered cartilage mechanical properties. Furthermore, it is well established that obesity is a primary risk factor for osteoarthritis. The purpose of this study was to inve ... Full text Open Access Link to item Cite

Four-Point Bending Testing for Mechanical Assessment of Mouse Bone Structural Properties.

Journal article Methods Mol Biol · 2021 One of the primary functions of bone is to support the skeleton by withstanding load. In the diseased state, bone's ability to perform this function is altered. Quantification of the features of bone that support its functional behavior, and how they may c ... Full text Link to item Cite

The Characteristic Recovery Time as a Novel, Noninvasive Metric for Assessing In Vivo Cartilage Mechanical Function.

Journal article Ann Biomed Eng · December 2020 Osteoarthritis (OA) is a disease characterized by the degeneration of cartilage tissue, and is a leading cause of disability in the United States. The clinical diagnosis of OA includes the presence of pain and radiographic imaging findings, which typically ... Full text Link to item Cite

The Influence of Obesity and Meniscal Coverage on In Vivo Tibial Cartilage Thickness and Strain.

Journal article Orthop J Sports Med · December 2020 BACKGROUND: Obesity, which potentially increases loading at the knee, is a common and modifiable risk factor for the development of knee osteoarthritis. The menisci play an important role in distributing joint loads to the underlying cartilage. However, th ... Full text Link to item Cite

Dose and Recovery Response of Patellofemoral Cartilage Deformations to Running.

Journal article Orthop J Sports Med · December 2020 BACKGROUND: Running is a common recreational activity that provides many health benefits. However, it remains unclear how patellofemoral cartilage is affected by varied running distances and how long it takes the cartilage to recover to its baseline state ... Full text Link to item Cite

Reconsidering Reciprocal Length Patterns of the Anteromedial and Posterolateral Bundles of the Anterior Cruciate Ligament During In Vivo Gait.

Journal article Am J Sports Med · July 2020 BACKGROUND: Some cadaveric studies have indicated that the anterior cruciate ligament (ACL) consists of anteromedial and posterolateral bundles that display reciprocal function with regard to knee flexion. However, several in vivo imaging studies have sugg ... Full text Link to item Cite

Inflammatory, Structural, and Pain Biochemical Biomarkers May Reflect Radiographic Disc Space Narrowing: The Johnston County Osteoarthritis Project.

Journal article J Orthop Res · May 2020 The purpose of this work is to determine the relationship between biomarkers of inflammation, structure, and pain with radiographic disc space narrowing (DSN) in community-based participants. A total of 74 participants (37 cases and 37 controls) enrolled i ... Full text Link to item Cite

Quantifying the biochemical state of knee cartilage in response to running using T1rho magnetic resonance imaging.

Journal article Sci Rep · February 5, 2020 Roughly 20% of Americans run annually, yet how this exercise influences knee cartilage health is poorly understood. To address this question, quantitative magnetic resonance imaging (MRI) can be used to infer the biochemical state of cartilage. Specificall ... Full text Open Access Link to item Cite

Comparison of Cartilage Mechanical Properties Measured During Creep and Recovery.

Journal article Sci Rep · January 31, 2020 The diagnosis of osteoarthritis (OA) currently depends on the presence of pain and radiographic imaging findings, which generally do not present until later stages of the disease when the condition is difficult to treat. Therefore, earlier detection of OA ... Full text Link to item Cite

In vivo attachment site to attachment site length and strain of the ACL and its bundles during the full gait cycle measured by MRI and high-speed biplanar radiography.

Journal article J Biomech · January 2, 2020 The purpose of this study was to measure in vivo attachment site to attachment site lengths and strains of the anterior cruciate ligament (ACL) and its bundles throughout a full cycle of treadmill gait. To obtain these measurements, models of the femur, ti ... Full text Link to item Cite

In Vivo Anterior Cruciate Ligament Deformation During a Single-Legged Jump Measured by Magnetic Resonance Imaging and High-Speed Biplanar Radiography.

Journal article Am J Sports Med · November 2019 BACKGROUND: The in vivo mechanics of the anterior cruciate ligament (ACL) and its bundles during dynamic activities are not completely understood. An improved understanding of how the ACL stabilizes the knee is likely to aid in the identification and preve ... Full text Link to item Cite

Meniscus-Derived Matrix Scaffolds Promote the Integrative Repair of Meniscal Defects.

Journal article Sci Rep · June 18, 2019 Meniscal tears have a poor healing capacity, and damage to the meniscus is associated with significant pain, disability, and progressive degenerative changes in the knee joint that lead to osteoarthritis. Therefore, strategies to promote meniscus repair an ... Full text Open Access Link to item Cite

In vivo assessment of the interaction of patellar tendon tibial shaft angle and anterior cruciate ligament elongation during flexion.

Journal article J Biomech · June 11, 2019 A potential cause of non-contact anterior cruciate ligament (ACL) injury is landing on an extended knee. In line with this hypothesis, studies have shown that the ACL is elongated with decreasing knee flexion angle. Furthermore, at low flexion angles the p ... Full text Link to item Cite

Osteoarthritis year in review 2018: mechanics.

Journal article Osteoarthritis Cartilage · March 2019 OBJECTIVE: To review recent biomechanics literature focused on the interactions between biomechanics and articular cartilage health, particularly focused on macro-scale and human studies. DESIGN: A literature search was conducted in PubMed using the search ... Full text Link to item Cite

A New Stress Test for Knee Joint Cartilage.

Journal article Sci Rep · February 19, 2019 Cartilage metabolism-both the synthesis and breakdown of cartilage constituents and architecture-is influenced by its mechanical loading. Therefore, physical activity is often recommended to maintain cartilage health and to treat or slow the progression of ... Full text Link to item Cite

Activities of daily living influence tibial cartilage T1rho relaxation times.

Journal article J Biomech · January 3, 2019 Quantitative T1rho magnetic resonance imaging (MRI) can potentially help identify early-stage osteoarthritis (OA) by non-invasively assessing proteoglycan concentration in articular cartilage. T1rho relaxation times are negatively correlated with proteogly ... Full text Link to item Cite

Selective Enzymatic Digestion of Proteoglycans and Collagens Alters Cartilage T1rho and T2 Relaxation Times.

Journal article Ann Biomed Eng · January 2019 Our objective was to determine the relationship of T1rho and T2 relaxation mapping to the biochemical and biomechanical properties of articular cartilage through selective digestion of proteoglycans and collagens. Femoral condyles were harvested from porci ... Full text Link to item Cite

Effects of Anterior Cruciate Ligament Deficiency on Tibiofemoral Cartilage Thickness and Strains in Response to Hopping.

Journal article Am J Sports Med · January 2019 BACKGROUND: Changes in knee kinematics after anterior cruciate ligament (ACL) injury may alter loading of the cartilage and thus affect its homeostasis, potentially leading to the development of posttraumatic osteoarthritis. However, there are limited in v ... Full text Link to item Cite

A Comparison of Knee Abduction Angles Measured by a 3D Anatomic Coordinate System Versus Videographic Analysis: Implications for Anterior Cruciate Ligament Injury.

Journal article Orthop J Sports Med · January 2019 BACKGROUND: Knee positions involved in noncontact anterior cruciate ligament (ACL) injury have been studied via analysis of injury videos. Positions of high ACL strain have been identified in vivo. These methods have supported different hypotheses regardin ... Full text Link to item Cite

Automatic registration of MRI-based joint models to high-speed biplanar radiographs for precise quantification of in vivo anterior cruciate ligament deformation during gait.

Journal article J Biomech · November 16, 2018 Understanding in vivo joint mechanics during dynamic activity is crucial for revealing mechanisms of injury and disease development. To this end, laboratories have utilized computed tomography (CT) to create 3-dimensional (3D) models of bone, which are the ... Full text Link to item Cite

Obesity alters the in vivo mechanical response and biochemical properties of cartilage as measured by MRI.

Journal article Arthritis Res Ther · October 17, 2018 BACKGROUND: Obesity is a primary risk factor for the development of knee osteoarthritis (OA). However, there remains a lack of in vivo data on the influence of obesity on knee cartilage mechanics and composition. The purpose of this study was to determine ... Full text Link to item Cite

In Vivo Assessment of Exercise-Induced Glenohumeral Cartilage Strain.

Journal article Orthop J Sports Med · July 2018 BACKGROUND: The human shoulder joint is the most mobile joint in the body. While in vivo shoulder kinematics under minimally loaded conditions have been studied, it is unclear how glenohumeral cartilage responds to high-demand loaded exercise. HYPOTHESIS: ... Full text Open Access Link to item Cite

Determination of the Position of the Knee at the Time of an Anterior Cruciate Ligament Rupture for Male Versus Female Patients by an Analysis of Bone Bruises.

Journal article Am J Sports Med · June 2018 BACKGROUND: The incidence of anterior cruciate ligament (ACL) ruptures is 2 to 4 times higher in female athletes as compared with their male counterparts. As a result, a number of recent studies have addressed the hypothesis that female and male patients s ... Full text Link to item Cite

A magnetic resonance imaging framework for quantifying intervertebral disc deformation in vivo: Reliability and application to diurnal variations in lumbar disc shape.

Journal article J Biomech · April 11, 2018 Low back pain is a significant socioeconomic burden in the United States and lumbar intervertebral disc degeneration is frequently implicated as a cause. The discs play an important mechanical role in the spine, yet the relationship between disc function a ... Full text Open Access Link to item Cite

Year in review: mechanics

Journal article Osteoarthritis and Cartilage · April 2018 Full text Cite

A comparison of patellofemoral cartilage morphology and deformation in anterior cruciate ligament deficient versus uninjured knees.

Journal article J Biomech · January 23, 2018 Anterior cruciate ligament (ACL) deficient patients have an increased rate of patellofemoral joint (PFJ) osteoarthritis (OA) as compared to the general population. Although the cause of post-injury OA is multi-factorial, alterations in joint biomechanics m ... Full text Link to item Cite

In Vivo Tibial Cartilage Strains in Regions of Cartilage-to-Cartilage Contact and Cartilage-to-Meniscus Contact in Response to Walking.

Journal article Am J Sports Med · October 2017 BACKGROUND: There are currently limited human in vivo data characterizing the role of the meniscus in load distribution within the tibiofemoral joint. Purpose/Hypothesis: The purpose was to compare the strains experienced in regions of articular cartilage ... Full text Link to item Cite

Effects of ACL graft placement on in vivo knee function and cartilage thickness distributions.

Journal article J Orthop Res · June 2017 Injuries to the anterior cruciate ligament (ACL) frequently lead to early-onset osteoarthritis. Despite advancement in surgical techniques, ACL reconstruction has a limited ability to prevent these degenerative changes. While previous studies have investig ... Full text Link to item Cite

Relationship between T1rho magnetic resonance imaging, synovial fluid biomarkers, and the biochemical and biomechanical properties of cartilage.

Journal article J Biomech · April 11, 2017 Non-invasive techniques for quantifying early biochemical and biomechanical changes in articular cartilage may provide a means of more precisely assessing osteoarthritis (OA) progression. The goals of this study were to determine the relationship between T ... Full text Link to item Cite

Matrix metalloproteinase activity and prostaglandin E2 are elevated in the synovial fluid of meniscus tear patients.

Journal article Connect Tissue Res · 2017 PURPOSE: Meniscus tears are a common knee injury and are associated with the development of post-traumatic osteoarthritis (OA). The purpose of this study is to evaluate potential OA mediators in the synovial fluid and serum of meniscus tear subjects compar ... Full text Link to item Cite

An analysis of changes in in vivo cartilage thickness of the healthy ankle following dynamic activity.

Journal article J Biomech · September 6, 2016 Abnormal cartilage loading after injury is believed to be an important factor leading to post-traumatic ankle osteoarthritis. Due to the viscoelastic behavior of cartilage, it is possible to measure localized cartilage strains from changes in thickness fol ... Full text Link to item Cite

Effect of normal gait on in vivo tibiofemoral cartilage strains.

Journal article J Biomech · September 6, 2016 Altered cartilage loading is believed to be associated with osteoarthritis development. However, there are limited data regarding the influence of normal gait, an essential daily loading activity, on cartilage strains. In this study, 8 healthy subjects wit ... Full text Link to item Cite

Knee Kinematics During Noncontact Anterior Cruciate Ligament Injury as Determined From Bone Bruise Location.

Journal article Am J Sports Med · October 2015 BACKGROUND: The motions causing noncontact anterior cruciate ligament (ACL) injury remain unclear. Tibiofemoral bone bruises are believed to be the result of joint impact near the time of ACL rupture. The locations and frequencies of these bone bruises hav ... Full text Link to item Cite

In vivo cartilage strain increases following medial meniscal tear and correlates with synovial fluid matrix metalloproteinase activity.

Journal article J Biomech · June 1, 2015 Meniscal tears are common injuries, and while partial meniscectomy is a frequent treatment option, general meniscus loss is a risk factor for the development of osteoarthritis. The goal of this study was to measure the in vivo tibiofemoral cartilage contac ... Full text Open Access Link to item Cite

In vivo measurement of localized tibiofemoral cartilage strains in response to dynamic activity.

Journal article Am J Sports Med · February 2015 BACKGROUND: Altered local mechanical loading may disrupt normal cartilage homeostasis and play a role in the progression of osteoarthritis. Currently, there are limited data quantifying local cartilage strains in response to dynamic activity in normal or i ... Full text Link to item Cite

The effects of femoral graft placement on cartilage thickness after anterior cruciate ligament reconstruction.

Journal article J Biomech · January 3, 2014 Altered joint motion has been thought to be a contributing factor in the long-term development of osteoarthritis after ACL reconstruction. While many studies have quantified knee kinematics after ACL injury and reconstruction, there is limited in vivo data ... Full text Link to item Cite

High body mass index is associated with increased diurnal strains in the articular cartilage of the knee.

Journal article Arthritis Rheum · October 2013 OBJECTIVE: Obesity is an important risk factor for osteoarthritis (OA) and is associated with changes in both the biomechanical and inflammatory environments within the joint. However, the relationship between obesity and cartilage deformation is not fully ... Full text Link to item Cite

Effects of cartilage impact with and without fracture on chondrocyte viability and the release of inflammatory markers.

Journal article J Orthop Res · August 2013 Post-traumatic arthritis (PTA) frequently develops after intra-articular fracture of weight bearing joints. Loss of cartilage viability and post-injury inflammation have both been implicated as possible contributing factors to PTA progression. To further i ... Full text Link to item Cite

In vivo measurement of ACL length and relative strain during walking.

Journal article J Biomech · February 1, 2013 Although numerous studies have addressed the effects of ACL injury and reconstruction on knee joint motion, there is currently little data available describing in vivo ACL strain during activities of daily living. Data describing in vivo ACL strain during ... Full text Link to item Cite

Diurnal variations in articular cartilage thickness and strain in the human knee.

Journal article J Biomech · February 1, 2013 Due to the biphasic viscoelastic nature of cartilage, joint loading may result in deformations that require times on the order of hours to fully recover. Thus, cartilaginous tissues may exhibit cumulative strain over the course of each day. The goal of thi ... Full text Link to item Cite

The effects of a valgus collapse knee position on in vivo ACL elongation.

Journal article Ann Biomed Eng · January 2013 There are conflicting data regarding what motions increase ACL injury risk. More specifically, the mechanical role of valgus collapse positions during ACL injury remains controversial. Our objective was to evaluate ACL elongation in a model that mimics kne ... Full text Link to item Cite

Immunofluorescence-guided atomic force microscopy to measure the micromechanical properties of the pericellular matrix of porcine articular cartilage.

Journal article J R Soc Interface · November 7, 2012 The pericellular matrix (PCM) is a narrow region that is rich in type VI collagen that surrounds each chondrocyte within the extracellular matrix (ECM) of articular cartilage. Previous studies have demonstrated that the chondrocyte micromechanical environm ... Full text Link to item Cite

The effect of modified Broström-Gould repair for lateral ankle instability on in vivo tibiotalar kinematics.

Journal article Am J Sports Med · September 2012 BACKGROUND: Lateral ankle instability leads to an increased risk of tibiotalar joint osteoarthritis. Previous studies have found abnormal tibiotalar joint motions with lateral ankle instability that may contribute to this increased incidence of osteoarthri ... Full text Link to item Cite

A biomechanical role for perlecan in the pericellular matrix of articular cartilage.

Journal article Matrix Biol · July 2012 Chondrocytes are surrounded by a narrow pericellular matrix (PCM) that is biochemically, structurally, and biomechanically distinct from the bulk extracellular matrix (ECM) of articular cartilage. While the PCM is often defined by the presence of type VI c ... Full text Link to item Cite

The effect of femoral tunnel placement on ACL graft orientation and length during in vivo knee flexion.

Journal article J Biomech · July 7, 2011 Anatomically placed grafts are believed to more closely restore the function of the ACL. This study measured the effect of femoral tunnel placement on graft orientation and length during weight-bearing flexion. Both knees of twelve patients where the graft ... Full text Link to item Cite

Acute joint pathology and synovial inflammation is associated with increased intra-articular fracture severity in the mouse knee.

Journal article Osteoarthritis Cartilage · July 2011 OBJECTIVE: Post-traumatic arthritis is a frequent cause of disability and occurs most commonly and predictably after articular fracture. The objective of this investigation was to examine the effect of fracture severity on acute joint pathology in a novel ... Full text Link to item Cite

Cartilage viability and catabolism in the intact porcine knee following transarticular impact loading with and without articular fracture.

Journal article J Orthop Res · April 2011 Posttraumatic arthritis commonly develops following articular fracture. The objective of this study was to develop a closed joint model of transarticular impact with and without creation of an articular fracture that maintains the physiologic environment d ... Full text Link to item Cite

The effects of femoral graft placement on in vivo knee kinematics after anterior cruciate ligament reconstruction.

Journal article J Biomech · March 15, 2011 Achieving anatomical graft placement remains a concern in Anterior Cruciate Ligament (ACL) reconstruction. The purpose of this study was to quantify the effect of femoral graft placement on the ability of ACL reconstruction to restore normal knee kinematic ... Full text Link to item Cite

Measurement of in vivo anterior cruciate ligament strain during dynamic jump landing.

Journal article J Biomech · February 3, 2011 Despite recent attention in the literature, anterior cruciate ligament (ACL) injury mechanisms are controversial and incidence rates remain high. One explanation is limited data on in vivo ACL strain during high-risk, dynamic movements. The objective of th ... Full text Link to item Cite

In vivo cartilage contact strains in patients with lateral ankle instability.

Journal article J Biomech · September 17, 2010 Damage to the anterior talofibular ligament (ATFL) and cacaneofibular ligament (CFL) during an ankle sprain may be linked to the development of osteoarthritis. Although altered tibiotalar kinematics have been demonstrated, the effects of lateral ankle inst ... Full text Link to item Cite

Increased tibiofemoral cartilage contact deformation in patients with anterior cruciate ligament deficiency.

Journal article Arthritis Rheum · December 2009 OBJECTIVE: To investigate the in vivo cartilage contact biomechanics of the tibiofemoral joint following anterior cruciate ligament (ACL) injury. METHODS: Eight patients with an isolated ACL injury in 1 knee, with the contralateral side intact, participate ... Full text Link to item Cite

In vivo kinematics of the tibiotalar joint after lateral ankle instability.

Journal article Am J Sports Med · November 2009 BACKGROUND: Previous studies have suggested that injury to the anterior talofibular ligament (ATFL) may be linked to altered kinematics and the development of osteoarthritis of the ankle joint. However, the effects of ATFL injury on the in vivo kinematics ... Full text Link to item Cite

Femoral tunnel placement during anterior cruciate ligament reconstruction: an in vivo imaging analysis comparing transtibial and 2-incision tibial tunnel-independent techniques.

Journal article Am J Sports Med · October 2009 BACKGROUND: Recent studies have questioned the ability of the transtibial technique to place the anterior cruciate ligament graft within the footprint of the anterior cruciate ligament on the femur. There are limited data directly comparing the abilities o ... Full text Link to item Cite

Three-dimensional analysis of cervical spine motion: reliability of a computer assisted magnetic tracking device compared to inclinometer.

Journal article Eur Spine J · February 2009 We aimed to investigate the reliability and reproducibility of a magnetic tracking technique for the assessment of overall cervical spine motion (principal and coupled movements). Ten asymptomatic male volunteers with a mean age of 29.3 years (range 20-37 ... Full text Link to item Cite

Reconstruction technique affects femoral tunnel placement in ACL reconstruction.

Journal article Clin Orthop Relat Res · June 2008 Grafts placed too anteriorly on the femur are reportedly a common cause of failure in anterior cruciate ligament reconstruction. Some studies suggest more anatomic femoral tunnel placement improves kinematics. The ability of the transtibial technique and a ... Full text Link to item Cite

The effect of anterior cruciate ligament deficiency and reconstruction on the patellofemoral joint.

Journal article Am J Sports Med · June 2008 BACKGROUND: Little is known about the effect of anterior cruciate ligament deficiency and reconstruction on the patellofemoral joint. HYPOTHESIS: Anterior cruciate ligament deficiency changes the patellofemoral joint biomechanics. Reconstruction of the lig ... Full text Link to item Cite

The quantification of the origin area of the deep forearm musculature on the interosseous ligament.

Journal article Bull NYU Hosp Jt Dis · 2008 The diagnosis and treatment of injuries involving rupture of the interosseous ligament remain challenging. Few studies have considered the effects of rupture of the interosseous ligament on deep forearm muscle function. The objective of this study was to q ... Link to item Cite

The coupled motion of the femur and patella during in vivo weightbearing knee flexion.

Journal article J Biomech Eng · December 2007 The movement of the knee joint consists of a coupled motion between the tibiofemoral and patellofemoral articulations. This study measured the six degrees-of-freedom kinematics of the tibia, femur, and patella using dual-orthogonal fluoroscopy and magnetic ... Full text Link to item Cite

Function of posterior cruciate ligament bundles during in vivo knee flexion.

Journal article Am J Sports Med · September 2007 BACKGROUND: The biomechanical functions of the anterolateral and posteromedial bundles of the posterior cruciate ligament over the range of flexion of the knee joint remain unclear. HYPOTHESIS: The posterior cruciate ligament bundles have minimal length at ... Full text Link to item Cite

The prediction of stress-relaxation of ligaments and tendons using the quasi-linear viscoelastic model.

Journal article Biomech Model Mechanobiol · July 2007 Recent studies have questioned the ability of the quasi-linear viscoelastic (QLV) model to predict stresses and strains in response to loading conditions other than those used to fit the model. The objective of this study was to evaluate the ability of sev ... Full text Link to item Cite

The effects of ACL deficiency on mediolateral translation and varus-valgus rotation.

Journal article Acta Orthop · June 2007 BACKGROUND: The anterior cruciate ligament (ACL) constrains the anterior translation and axial rotation of the tibia. However, the effect of ACL injury on the mediolateral translation and varus-valgus rotation of the tibia is unknown. Because of the obliqu ... Full text Link to item Cite

The in vivo kinematics of the anteromedial and posterolateral bundles of the anterior cruciate ligament during weightbearing knee flexion.

Journal article Am J Sports Med · April 2007 BACKGROUND: Recently, double-bundle anterior cruciate ligament reconstruction has been advocated. However, there are little data on the in vivo biomechanics of the anteromedial and posterolateral bundles of the anterior cruciate ligament. Our objective was ... Full text Link to item Cite

The effect of anterior cruciate ligament deficiency on the in vivo elongation of the medial and lateral collateral ligaments.

Journal article Am J Sports Med · February 2007 BACKGROUND: Although anterior cruciate ligament deficiency has been shown to lead to joint degeneration, few quantitative data have been reported on its effect on soft tissue structures surrounding the knee joint. HYPOTHESIS: Anterior cruciate ligament def ... Full text Link to item Cite

The biomechanical function of the patellar tendon during in-vivo weight-bearing flexion.

Journal article J Biomech · 2007 Few studies have investigated the function of the patellar tendon in-vivo. This study quantified the three-dimensional (3D) kinematics of the patellar tendon during weight-bearing flexion. Eleven subjects were imaged using magnetic resonance (MR). Sagittal ... Full text Link to item Cite

In vivo kinematics of the knee after anterior cruciate ligament reconstruction: a clinical and functional evaluation.

Journal article Am J Sports Med · December 2006 BACKGROUND: Recent follow-up studies have reported a high incidence of joint degeneration in patients with anterior cruciate ligament reconstruction. Abnormal kinematics after anterior cruciate ligament reconstruction have been thought to contribute to the ... Full text Link to item Cite

The 6 degrees of freedom kinematics of the knee after anterior cruciate ligament deficiency: an in vivo imaging analysis.

Journal article Am J Sports Med · August 2006 BACKGROUND: Previous studies of knee joint function after anterior cruciate ligament deficiency have focused on measuring anterior-posterior translation and internal-external rotation. Few studies have measured the effects of anterior cruciate ligament def ... Full text Link to item Cite

Anterior cruciate ligament deficiency alters the in vivo motion of the tibiofemoral cartilage contact points in both the anteroposterior and mediolateral directions.

Journal article J Bone Joint Surg Am · August 2006 BACKGROUND: Quantifying the effects of anterior cruciate ligament deficiency on joint biomechanics is critical in order to better understand the mechanisms of joint degeneration in anterior cruciate ligament-deficient knees and to improve the surgical trea ... Full text Link to item Cite

Comparison of the ACL and ACL graft forces before and after ACL reconstruction: an in-vitro robotic investigation.

Journal article Acta Orthop · April 2006 BACKGROUND: Long-term follow-up studies have indicated that there is an increased incidence of arthrosis following anterior cruciate ligament (ACL) reconstruction, suggesting that the reconstruction may not reproduce intact ACL biomechanics. We studied not ... Full text Link to item Cite

The measurement of the variation in the surface strains of Achilles tendon grafts using imaging techniques.

Journal article J Biomech · 2006 Uniaxial tensile tests are commonly used to characterize the structural and material properties of tendons and ligaments. During these tests, the stress and strain distributions applied to the specimen are assumed to be uniform. However, few studies have i ... Full text Link to item Cite

Erratum to "The change in length of the medial and lateral collateral ligaments during in vivo knee flexion".

Journal article Knee · January 2006 The collateral ligaments of the knee are important in maintaining knee stability. However, little data has been reported on the in vivo function of the collateral ligaments. The objective of this study was to investigate the change in length of different f ... Full text Link to item Cite

The measurement of the variation in the surface strains of achilles tendon grafts using imaging techniques

Journal article Proceedings of the 2005 Summer Bioengineering Conference · December 1, 2005 Cite

The development of an orthogonal fluoroscopic and MR imaging technique for accurately measuring in vivo knee joint kinematics

Journal article Proceedings of the 2005 Summer Bioengineering Conference · December 1, 2005 Cite

The prediction of the stress-strain behavior of ligaments and tendons

Journal article Proceedings of the 2005 Summer Bioengineering Conference · December 1, 2005 Cite

The change in length of the medial and lateral collateral ligaments during in vivo knee flexion.

Journal article Knee · October 2005 The collateral ligaments of the knee are important in maintaining knee stability. However, little data has been reported on the in vivo function of the collateral ligaments. The objective of this study was to investigate the change in length of different f ... Full text Link to item Cite

The cartilage thickness distribution in the tibiofemoral joint and its correlation with cartilage-to-cartilage contact.

Journal article Clin Biomech (Bristol) · August 2005 OBJECTIVE: The objective of this study was to investigate whether regions of cartilage in the tibiofemoral joint where cartilage-to-cartilage contact occurred was thicker than other regions. DESIGN: In vivo human subjects. BACKGROUND: The thickness of the ... Full text Link to item Cite

In vivo kinematics of the ACL during weight-bearing knee flexion.

Journal article J Orthop Res · March 2005 No study has investigated the three-dimensional morphological changes of the anterior cruciate ligament (ACL) during functional activities in vivo. The purpose of this study was to analyze the elongation, rotation (twist), and orientation of the ACL during ... Full text Link to item Cite

The effect of anterior cruciate ligament reconstruction on knee joint kinematics under simulated muscle loads.

Journal article Am J Sports Med · February 2005 BACKGROUND: Numerous studies have investigated anterior stability of the knee during the anterior drawer test after anterior cruciate ligament reconstruction. Few studies have evaluated anterior cruciate ligament reconstruction under physiological loads. P ... Full text Link to item Cite

In vivo articular cartilage contact kinematics of the knee: an investigation using dual-orthogonal fluoroscopy and magnetic resonance image-based computer models.

Journal article Am J Sports Med · January 2005 BACKGROUND: Quantifying the in vivo cartilage contact mechanics of the knee may improve our understanding of the mechanisms of joint degeneration and may therefore improve the surgical repair of the joint after injury. OBJECTIVE: To measure tibiofemoral ar ... Full text Link to item Cite

In vivo function of the posterior cruciate ligament during weightbearing knee flexion.

Journal article Am J Sports Med · December 2004 BACKGROUND: Current knowledge of posterior cruciate ligament function is mainly based on in vitro cadaveric studies. There are few studies on the in vivo function of the posterior cruciate ligament. The objective of the study was to quantify the multidimen ... Full text Link to item Cite

In vivo tibiofemoral contact analysis using 3D MRI-based knee models.

Journal article J Biomech · October 2004 This paper quantified the motion of the tibiofemoral contact points during in vivo weight bearing flexion using MRI- based 3D knee models and two orthogonal fluoroscopic images. The contact points on the medial and lateral tibial plateau were calculated by ... Full text Link to item Cite

The effect of posterior knee capsulotomy on posterior tibial translation during posterior cruciate ligament tibial inlay reconstruction.

Journal article Am J Sports Med · September 2004 PURPOSE: To measure the biomechanical effect of the surgical capsulotomy made during a posterior cruciate ligament reconstruction using the tibial inlay technique. HYPOTHESIS: The posterior capsule contributes to posterior tibial stability. STUDY DESIGN: C ... Full text Link to item Cite

In vivo elongation of the anterior cruciate ligament and posterior cruciate ligament during knee flexion.

Journal article Am J Sports Med · September 2004 BACKGROUND: Most knowledge regarding cruciate ligament function is based on in vitro experiments. PURPOSE: To investigate the in vivo elongation of the functional bundles of the anterior cruciate ligament and posterior cruciate ligament during weightbearin ... Full text Link to item Cite

The effect of tibiofemoral joint kinematics on patellofemoral contact pressures under simulated muscle loads.

Journal article J Orthop Res · July 2004 Altered patellofemoral joint contact pressures are thought to contribute to patellofemoral joint symptoms. However, little is known about the relationship between tibiofemoral joint kinematics and patellofemoral joint contact pressures. The objective of th ... Full text Link to item Cite

The effect of length on the structural properties of an Achilles tendon graft as used in posterior cruciate ligament reconstruction.

Journal article Am J Sports Med · June 2004 BACKGROUND: The clinical outcomes of posterior cruciate ligament reconstruction are varied. No previous studies have investigated the effect of graft length on the structural properties of the graft. HYPOTHESIS: Graft length significantly affects the struc ... Full text Link to item Cite

Effect of the posterior cruciate ligament on posterior stability of the knee in high flexion.

Journal article J Biomech · May 2004 Most biomechanical studies of the knee have focused on knee flexion angles between 0 degrees and 120 degrees. The posterior cruciate ligament (PCL) has been shown to constrain posterior laxity of the knee in this range of flexion. However, little is known ... Full text Link to item Cite

Feasibility of using orthogonal fluoroscopic images to measure in vivo joint kinematics.

Journal article J Biomech Eng · April 2004 Accurately determining in vivo knee kinematics is still a challenge in biomedical engineering. This paper presents an imaging technique using two orthogonal images to measure 6 degree-of-freedom (DOF) knee kinematics during weight-bearing flexion. Using th ... Full text Link to item Cite

In situ forces of the anterior and posterior cruciate ligaments in high knee flexion: an in vitro investigation.

Journal article J Orthop Res · March 2004 The function of the anterior and posterior cruciate ligaments (ACL and PCL) in the first 120 degrees of flexion has been reported extensively, but little is known of their behavior at higher flexion angles. The aim of this investigation was to study the ef ... Full text Link to item Cite

Kinematics of the knee at high flexion angles: an in vitro investigation.

Journal article J Orthop Res · January 2004 Restoration of knee function after total knee, meniscus, or cruciate ligament surgery requires an understanding of knee behavior throughout the entire range of knee motion. However, little data are available regarding knee kinematics and kinetics at flexio ... Full text Link to item Cite

The effect of posterior cruciate ligament reconstruction on patellofemoral contact pressures in the knee joint under simulated muscle loads.

Journal article Am J Sports Med · 2004 BACKGROUND: The mechanism of cartilage degeneration in the patellofemoral joint (PFJ) and medial compartment of the knee following posterior cruciate ligament (PCL) injury remains unclear. PCL reconstruction has been recommended to restore kinematics and p ... Full text Link to item Cite

In vivo tibiofemoral contact analysis using 3D MRI-based Knee model

Journal article Journal of Biomechanics · 2004 Cite

Determination of optimal graft lengths for posterior cruciate ligament reconstruction--a theoretical analysis.

Journal article J Biomech Eng · April 2003 Various graft materials have been used in posterior cruciate ligament (PCL) reconstruction. However, it is unclear if these grafts can reproduce the structural behavior of the PCL. This paper analyzed the effect of graft length on the structural behavior o ... Full text Link to item Cite

The biomechanical effect of posterior cruciate ligament reconstruction on knee joint function. Kinematic response to simulated muscle loads.

Journal article Am J Sports Med · 2003 BACKGROUND: The effectiveness of posterior cruciate ligament reconstruction in restoring normal kinematics under physiologic loading is unknown. HYPOTHESIS: Posterior cruciate ligament reconstruction does not restore normal knee kinematics under muscle loa ... Full text Link to item Cite

Biomechanical consequences of PCL deficiency in the knee under simulated muscle loads--an in vitro experimental study.

Journal article J Orthop Res · July 2002 The mechanism of chronic degeneration of the knee after posterior cruciate ligament (PCL) injury is still not clearly understood. While numerous biomechanical studies have been conducted to investigate the function of the PCL with regard to antero-posterio ... Full text Link to item Cite

A minimally invasive method for the determination of force in the interosseous ligament.

Journal article Clin Biomech (Bristol) · December 2001 OBJECTIVE: The objective was to develop and utilize a minimally invasive testing system to determine the force in the interosseous ligament under axial compressive loads across the range of motion of the human forearm. DESIGN: Eleven fresh frozen human cad ... Full text Link to item Cite

Magnetic tracking/virtual reality based system for comprehensive kinematic assessment of the cervical spine

Journal article American Society of Mechanical Engineers Bioengineering Division Publication BED · December 1, 1999 A magnetic tracking/virtual reality based system for comprehensive kinematic assessment of the cervical spine is described. The system is designed to enable accurate and precise measurement, description, and control of the movements of the head relative to ... Cite

Virtual reality assisted visual feedback of cervical spine kinematics for improved control of active range-of-motion maneuvers

Journal article American Society of Mechanical Engineers Bioengineering Division Publication BED · December 1, 1999 The current study investigated the efficacy of virtual reality (VR) assisted visual feedback for improving control of voluntary movements of the cervical spine during performance of active range-of-motion maneuvers. Active range-of-motion was assessed in 1 ... Cite

Axial rotation limits cervical spine flexion-extension range of motion

Journal article American Society of Mechanical Engineers Bioengineering Division Publication BED · December 1, 1997 Cite

Virtual reality assisted measurement of in-vivo cervical spine kinematics

Journal article American Society of Mechanical Engineers Bioengineering Division Publication BED · December 1, 1997 Cite