About

Scott Delp is the James H. Clark Professor in the School of Engineering at Stanford University, where he also holds positions as a Professor of Bioengineering, Mechanical Engineering, and by courtesy, of Orthopaedic Surgery. His work is centered on the intersection of artificial intelligence, medicine, and imaging, with a focus on advancing healthcare through innovative research in these areas. As a key figure at the Stanford Center for Artificial Intelligence in Medicine & Imaging (AIMI), he contributes to the development of AI-driven solutions for medical imaging and healthcare applications, aiming to improve patient outcomes and transform medical practices.

Research topics

• Computer Science
• Artificial Intelligence
• Medicine
• Machine Learning
• Physical medicine and rehabilitation
• Simulation
• Psychology
• Physical therapy
• Engineering
• Human–computer interaction
• Pathology
• Social Science
• Sociology
• Internal medicine
• Embedded system
• Political Science
• Nursing
• Public relations
• Mathematics
• Statistics
• Social psychology
• Neuroscience
• Radiology
• Surgery

Selected publications

• BMI and Varus Malalignment Compound to Define a High-Risk Phenotype for Compartment-Specific Knee Osteoarthritis Progression

  medRxiv · 2026-04-17

  articleOpen access

  Objectives: Knee osteoarthritis (KOA) is a leading cause of disability, yet which patients will experience structural decline remains unclear. Body mass index (BMI) and lower limb alignment are established risk factors for KOA, but their independent and interactive effects on compartment-specific cartilage loss and total knee replacement (TKR) have not been characterized at scale. Methods: We analyzed 5,832 limbs from 3,016 participants in the Osteoarthritis Initiative followed over 7 years. Cartilage thickness in the weight-bearing medial and lateral femur and tibia was quantified, and lower limb alignment was measured using hip-knee-ankle (HKA) angle obtained from full-limb radiographs. Linear mixed-effects models estimated the independent and interactive effects of BMI and lower limb alignment on longitudinal cartilage thinning, and mixed-effects logistic regression modeled TKR risk. Results: BMI and +10° varus, the rate of medial femur cartilage thinning was 243.5% faster than the reference rate. In the lateral compartment, BMI and valgus alignment were independently associated with faster cartilage thinning, with no significant interaction. TKR risk increased exponentially with HKA deviation (odds ratio [OR] = 1.38 per 1°; ~five-fold at 5° malalignment) but was not associated with BMI. Conclusion: BMI and lower limb alignment influence structural KOA progression through compartment-specific pathways. The multiplicative interaction in the medial compartment identifies high BMI combined with varus malalignment as a discrete high-risk phenotype, with implications for clinical risk stratification and disease-modifying intervention design.

  PublisherDOI

• Detecting artificially impaired balance in human locomotion: metrics, perturbation effects and detection thresholds

  Journal of Experimental Biology · 2025-05-15 · 6 citations

  articleOpen access

  Measuring balance is important for detecting impairments and developing interventions to prevent falls, but there is no consensus on which method is most effective. Many balance metrics derived from steady-state walking data have been proposed, such as step-width variability, step-time variability, foot placement predictability, maximum Lyapunov exponent and margin of stability. Recently, perturbation-based metrics such as center of mass displacement have also been explored. Perturbations typically involve unexpected disturbances applied to the subject. In this study we collected walking data from 10 healthy human subjects while walking normally and while impairing balance with ankle braces, eye-blocking masks and pneumatic jets on their legs. In some walking trials we also applied mechanical perturbations to the pelvis. We obtained a comprehensive biomechanics dataset and compared the ability of various metrics to detect impaired balance using steady-state walking and perturbation recovery data. We also compared metric performance using thresholds informed by data from multiple subjects versus subject-specific thresholds. We found that step-width variability, step-time variability and foot placement predictability, using steady-state data and subject-specific thresholds, detected impaired balance with the highest accuracy (≥86%), whereas other metrics were less effective (≤68%). Incorporating perturbation data did not improve accuracy of these metrics, although this comparison was limited by the small amount of perturbation data included and analyzed. Subject-specific baseline measurements improved the detection of changes in balance ability. Thus, in clinical practice, taking baseline measurements might improve the detection of impairment due to aging or disease progression.

  PublisherOA PDFDOI

• Hamstring Muscle Architecture and Microstructure Changes Following 9-weeks of Nordic Hamstring Exercise Training

  Proceedings on CD-ROM - International Society for Magnetic Resonance in Medicine. Scientific Meeting and Exhibition/Proceedings of the International Society for Magnetic Resonance in Medicine, Scientific Meeting and Exhibition · 2025-09-16

  article

  Motivation: Evaluate long-term muscle adaptations across the full volume of all four hamstrings in response to Nordic hamstring exercise (NHE) to enhance injury prevention strategies. Goal(s): Examine how 9-weeks of supervised NHE-training affects architecture (volume, fiber length, angle, and curvature) and microstructure (MD, RD, FA, and T2) of Biceps femoris short head (BFsh), Biceps femoris long head (BFlh), Semitendinosus (ST), and Semimembranosus (SM). Approach: 11 subjects underwent MRI scans (Dixon, DTI, and T2) pre and post 9-weeks NHE-training. Results: NHE-training increased hamstring volume with greater hypertrophy in ST and BFsh muscles. Hypertrophy was accompanied by increases in both length and cross-section of muscle fibers. Impact: This study examines architectural and microstructural adaptations of the hamstrings following 9-weeks of Nordic hamstring exercise training. Findings reveal significant, but non-uniform hypertrophy among hamstrings accompanied by increase in length and size of the muscle fibers, advancing injury prevention strategies.

  PublisherDOI

• Running with an Exotendon Reduces Compressive Knee Contact Force

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-11-20

  preprintOpen accessSenior author

  Abstract An exotendon—a spring that couples the dynamics of the legs when attached to a runner’s shoes—reduces the energetic cost of running, but the effects on joint contact forces are unknown. This study examined whether running with an exotendon alters the forces in the hip, knee and ankle. We used muscle-driven simulations of experimental data to compute compressive and shear contact forces at the hip, knee, and ankle joints for five participants running at 2.7 m/s with and without an exotendon. We found that runners using the exotendon experienced a 9.4% reduction in peak knee compressive contact force (1.0 ± 0.6 BW; P =0.036), and no change in the peak knee shear contact force. The primary contributor to this reduction was lower forces in the quadriceps muscles, which decreased their contribution to peak knee compressive contact force by 14.2% (-0.9 ± 0.6 BW; P=0.026). We observed no change in the peak compressive or shear contact forces in the hip or ankle joints. Though the exotendon was not originally designed to reduce joint forces, our findings highlight the ability of this simple device to make changes to gait that reduce both energetic cost and compressive knee force.

  PublisherOA PDFDOI

• Personalised gait retraining for medial compartment knee osteoarthritis: a randomised controlled trial

  The Lancet Rheumatology · 2025-08-12 · 18 citations

  articleOpen access
  PublisherOA PDFDOI

• Hamstring muscle architecture and microstructure changes following Nordic hamstring exercise training and detraining

  Journal of sport and health science/Journal of Sport and Health Science · 2025-06-25 · 4 citations

  articleOpen access

  • Nine weeks of Nordic hamstring exercise training substantially increased hamstring muscle volume as well as fiber length and cross-section. • Nordic hamstring exercise induced non-uniform adaptations across the 4 hamstring muscles; the hypertrophy and fiber length elongation were greater in the semitendinosus and biceps femoris short head compared to the semimembranosus and biceps femoris long head. • Upon 3 weeks of detraining, gains in fiber length underwent rapid reversal, but gains in volume and fiber cross-section were mostly retained, which underscores the need for consistent training to sustain all the protective benefits imparted by the exercise. Background While Nordic hamstring exercise (NHE) training has been shown to reduce hamstring strains, the muscle-specific adaptations to NHE across the 4 hamstrings remain unclear. This study investigates architectural and microstructural adaptations of the biceps femoris short head (BFsh), biceps femoris long head (BFlh), semitendinosus (ST), and semimembranosus (SM) in response to an NHE intervention. Methods Eleven subjects completed 9 weeks of supervised NHE training followed by 3 weeks of detraining. Magnetic resonance imaging was performed at pre-training, post-training, and detraining to assess architectural (volume, fiber tract length, and fiber tract angle) and microstructural (axial (AD), mean (MD), radial (RD) diffusivities, and fractional anisotropy (FA)) parameters of the 4 hamstrings. Results NHE training induced significant but non-uniform hamstring muscle hypertrophy (BFsh: 22%, BFlh: 9%, ST: 26%, SM: 6%) and fiber tract length increase (BFsh: 11%, BFlh: 7%, ST: 18%, SM: 10%). AD (5%), MD (4%), and RD (5%) showed significant increases, but fiber tract angle and FA remained unchanged. After detraining, only ST showed a significant reduction (8%) in volume, which remained higher than the pre-training value. While fiber tract lengths returned to baseline, AD, MD, and RD remained higher than pre-training levels for all hamstrings. Conclusion The 9-week NHE training substantially increased hamstring muscle volume with greater hypertrophy in ST and BFsh. Hypertrophy was accompanied by increases in fiber tract lengths and cross-sections (increased RD). After 3 weeks of detraining, fiber tract length gains across all hamstrings declined, emphasizing the importance of sustained training to maintain all the protective adaptations.

  PublisherDOI

• Knee and Hip Joint Dynamics Differ between Sprinting and Nordic Hamstring Exercises

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-08-21

  preprintOpen accessSenior author

  Abstract Background Sprinting and Nordic hamstring exercise (NHE) programs are common training modalities used to reduce hamstring injury risk, but the differences in the biomechanical demands of sprinting and the NHE are unclear. The purpose of this study was to compare knee and hip joint kinematics and kinetics, and hamstrings muscle-tendon unit (MTU) length and velocity during the flight phase of sprinting and the NHE. Methods We collected motion capture and force data from fourteen young athletic participants (8 males and 6 females) as they ran at a range of speeds (4–8 m/s) and performed the NHE. We used this experimental data and a musculoskeletal model to compute joint angles, moments, work, and power and to estimate the hamstrings MTU length and velocity for all running speeds and the NHE. Results The peak knee flexion moment at running speeds of 6 m/s and above was greater than for the NHE ( p < 0.001). Peak negative knee flexion power at all running speeds was higher than during the NHE ( p < 0.001). Negative knee flexion work at running speeds of 6 m/s and slower was less than during the NHE ( p < 0.001). Peak hamstrings length and lengthening velocity were greater ( p < 0.001) for all running speeds compared to the NHE. Conclusion Sprinting puts the hamstrings at longer hamstrings lengths and higher hamstrings lengthening velocities than the NHE. The NHE requires participants to generate peak knee flexion moments that are smaller than the peak knee flexion moments generated during top speed sprinting and peak negative knee flexion powers that are less than 5% of sprinting. However, the duration of each NHE repetition is approximately 60 times longer than the hamstrings lengthening portion of the flight phase of running, resulting in comparable negative knee work. The results of this study provide necessary quantitative information to compare the biomechanical demands of sprinting and the NHE.

  PublisherOA PDFDOI

• PREDICTING SAVINGS IN THE METABOLIC COST OF RUNNING WITH AN EXOTENDON

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-04-21 · 1 citations

  preprintOpen accessSenior author

  ABSTRACT The exotendon is a passive device that reduces the energetic cost of running at 2.7 m/s, but its potential benefits at higher speeds remain unknown. Experimental testing is challenging because of the wide range of conditions that must be tested. Here, we use muscle-driven simulations to overcome this challenge and inform exotendon design. We validated a simulation framework that estimates changes in energy expenditure, body kinematics, and muscle activations when simulated subjects run with and without an exotendon. Simulations of people running at 4 m/s with the exotendon that saved energy at 2.7 m/s predicted a 10% reduction in energy cost compared to natural running. We then performed simulations of 25 designs and found that many of the designs saved energy. A longer, stiffer exotendon yielded slightly greater energy savings (12%). Longer and more compliant exotendons offered little savings. We plan to test a limited set of our simulation predictions in an experiment to evaluate their accuracy and assess how an exotendon impacts running performance at 4 m/s. The purpose of this paper is to present the simulation results and to make predictions about the performance of the runner-exotendon system in experiments. This paper has been posted before the experiments have begun to avoid informing the predictions from the experimental results.

  PublisherOA PDFDOI

• PATIENT-SPECIFIC CARTILAGE PRESSURES ARE RELATED TO OSTEOARTHRITIS PROGRESSION AND DISEASE SEVERITY

  Osteoarthritis and Cartilage · 2025-04-01

  article
  PublisherDOI

• A simplified wearable device powered by a generative EMG network for hand-gesture recognition and gait prediction

  Nature Sensors · 2025-12-01 · 11 citations

  article
  PublisherDOI

Recent grants

• NIH Grant U54EB020405

  NIH · $23.2M · 2019

• NIH Grant R01HD046814

  NIH · $1.4M · 2010

• NIH Grant R01GM107340

  NIH · $1.9M · 2019

• NIH Grant R24HD065690

  NIH · $4.2M · 2015

• NIH Grant R01HD033929

  NIH · $2.6M · 2012

Frequent coauthors

• Garry E. Gold

  108 shared

• Jennifer L. Hicks

  Georgetown University

  100 shared

• Gary S. Beaupré

  78 shared

• Thor F. Besier

  University of Auckland

  56 shared

• Michael Schwartz

  Gillette Children's Specialty Healthcare

  44 shared

• Łukasz Kidziński

  43 shared

• Scott D. Uhlrich

  42 shared

• Silvia S. Blemker

  Purdue University West Lafayette

  36 shared