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Karin Gravare Silbernagel - University of Delaware. Newark, DE, US

Karin Gravare Silbernagel

Professor, Physical Therapy | University of Delaware


Prof. Silbernagel's research aims to advance the understanding of tendon and ligament injuries and repair.





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Karin Grävare Silbernagel 93. Achilles Tendinopathy and Achilles Tendon Ruptures w/ Karin Silbernagel Karin Silbernagel - Rehabilitation of achilles injuries in athletes - #SportsKonres 2019




Karin Grävare Silbernagel PT, ATC, PhD is a Professor & Associate Chair in the Department of Physical Therapy and the Director of the Center for Human Research Coordination at the University of Delaware, Newark, DE. She has been a Physical Therapist and Athletic Trainer for 30 years and performed research on tendon injuries for 20 years. Her expertise is in orthopaedics and musculoskeletal injury with a focus on tendon and ligament injury. At University of Delaware she is the principal investigator of the Delaware Tendon Research Group and the Delaware ACL Research Group. Her work has been directly integrated into the clinical guidelines for treatment of patients with tendon injuries. She has presented her research at numerous conferences and published in peer-reviewed journals (140+ published articles to date). She has also been invited to speak about her research at conferences nationally and internationally. As the principal investigator of Tendon Research Group at the University of Delaware she is working to advance understanding of tendon injuries and repair so that tailored treatments can be developed. Her research approach is to evaluate tendon health and recovery by quantifying tendon composition, structure, and mechanical properties, as well as patients’ impairments and symptoms. She consults with professional sports team relating to tendon injuries and she is a consultant to the NFL's Musculoskeletal Committee. Her research is funded by the NIH, Foundation for Physical Therapy, Swedish Research Council for Sport Science, and Swedish Research Council.

Industry Expertise (1)

Health and Wellness

Areas of Expertise (5)

Achilles Tendinopathy

Patellar Tendinopathy

Achilles Tendon Rupture

Tendon Rupture

Knee Injuries

Media Appearances (5)

Matchmakers for research

University of Delaware  online


“Everyone wants a treatment for their problem,” said Karin Grävare Silbernagel, director of the University of Delaware’s Center for Human Research Coordination and professor in the Department of Physical Therapy in the College of Health Sciences. “Volunteers can be heroes by being part of the research.”

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Does Early Mobilization Improve Achilles Tendon Outcomes?

Orrthopedics This Week  online


Study authors included Susanna Aufwerber, PT, Ph.D., Paul W. Ackermann, M.D., Ph.D. and Josefine E. Naili, PT, Ph.D., all from the Karolinska Institute, Stockholm, Sweden. Karin Grävare Silbernagel, PT, ATC, Ph.D. of the University of Delaware, Newark, also contributed to the study.

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FB Barcelona  online


For her part, Dr. Karin Grävare Silbernagel, associate professor at the University of Delaware, analysed both tendinopathy and ruptures of the Achilles tendon. She explained that Achilles rupture occurs suddenly, has a cumulative incidence among athletes under 45 years of age of 5.4% and rarely presents previous symptoms.

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Kevin Durant's Achilles Tendon: What to Know

Heathline  online


“When it happens you feel a sharp pain, and often the person thinks someone hit them or stepped on them in the back of the Achilles tendon, you can also hear a loud pop that all the surrounding individuals will hear,” said Karin Grävare Silbernagel, PhD, a physical therapist and associate professor at the University of Delaware. “After the initial pain you actually have very minor symptoms and that is why this sometimes goes undiagnosed.”

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NIH gives UD professor $2.3 million for study of Achilles injuries

University of Delaware  online


University of Delaware assistant professor Karin Grävare Silbernagel (Physical Therapy) received a five-year, $2.3 million Research Project Grant (R01) from the National Institute of Arthritis and Musculoskeletal and Skin Diseases to study Achilles tendinopathy. This overuse injury is most prevalent in active individuals between the ages of 35 and 55, but occurs in people of all ages and activity levels.

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Articles (5)

Effect of Symptom Duration on Injury Severity and Recovery in Patients With Achilles Tendinopathy

Orthopaedic Journal of Sports Medicine

2023 Background: Achilles tendinopathy is a common overuse condition. Distinguishing between early- and late-stage tendinopathy may have implications on treatment decisions and recovery expectations. Purpose: To compare the effects of time and baseline measures of tendon health on outcomes among patients with varying symptom durations after 16 weeks of comprehensive exercise treatment.

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Overload in a Rat in Vivo Model of Synergist Ablation Induces Tendon Multi-scale Structural and Functional Degeneration

Journal of Biomechanical Engineering

2023 Tendon degeneration is typically described as an overuse injury with little distinction made between magnitude of load (overload) and number of cycles (overuse). Further, in vivo animal models of tendon degeneration are mostly overuse models, where tendon damage is caused with high number of load cycles. As a result, there is a lack of knowledge of how isolated overload leads to degeneration. A surgical model of synergist ablation (SynAb) overloads the target tendon, plantaris, by ablating its synergist tendon, Achilles. The objective of this study was to evaluate the structural and functional changes that occur following overload of plantaris tendon in a rat SynAb model.

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Presence of early radiographic features of osteoarthritis differs between subgroups 5 years after anterior cruciate ligament injury

Osteoarthritis and Cartilage

2023 Purpose: Outcomes after anterior cruciate ligament (ACL) rupture vary highly across individuals. Data suggests up to 35% of patients do not return to pre-injury sport, anywhere from 12-27% of patients sustain a second injury, and over 50% develop posttraumatic osteoarthritis (OA). These data suggest there may be subgroups that exist among those who have ruptured their ACL. Posttraumatic osteoarthritis (PTOA) in the knee joint is one of many concerning long-term outcomes facing individuals who have torn their ACL. Recent data suggest that 50-80% of individuals develop PTOA within 10 years of ACL reconstruction (ACLR). Most who undergo ACLR are young and active, leaving them at a high risk of developing PTOA in young adulthood. There is a need to identify characteristics of individuals who are at greater risk for negative long-term outcomes enabling insight into targeted treatments.

Challenging the assumption of uniformity in patellar tendon structure: Regional patellar tendon morphology and mechanical properties in vivo

Journal of Orthopaedic Research

2023 Patellar tendons are assumed to be uniform in morphology and mechanical properties despite a higher prevalence of tendinopathies observed in the medial region. The purpose of this study was to compare the thickness, length, viscosity, and shear modulus of the medial, central, and lateral regions of healthy patellar tendons of young males and females in vivo. B‐mode ultrasound and continuous shear wave elastography were performed on 35 patellar tendons (17 females, 18 males) over three regions of interest. A linear mixed‐effects model (α = 0.05) was used to determine differences between the three regions and sexes followed by pairwise comparisons for significant findings. The lateral region (mean (95% CI) = 0.34 (0.31‐0.37) cm) was thinner compared to the medial (0.41 (0.39‐0.44) cm, p < 0.001), and central (0.41 (0.39‐0.44) cm, p < 0.001) regions regardless of sex.

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Differences in Recovery of Tendon Health Explained by Midportion Achilles Tendinopathy Subgroups: A 6-Month Follow-up

Journal of Orthopaedic & Sports Physical Therapy

2023 OBJECTIVES: To (1) evaluate whether the defining characteristics of previously reported Achilles tendinopathy subgroups were reproducible in a cohort with midportion Achilles tendinopathy and (2) compare recovery trajectories and outcomes. DESIGN: Prospective single cohort study. METHODS: Participants (n = 114; 57 women; age [mean ± standard deviation]: 47 ± 12 years) received the Silbernagel protocol and were evaluated at baseline, and at 8, 16, and 24 weeks. Subgroups were identified using mixture modeling. Main effects of group and time, and interaction effects were evaluated using linear mixed models for 23 outcome measures representing symptoms, lower extremity function, tendon structure, psychological factors, and patient-related factors. Recovery trajectories were reported descriptively to reflect clinically meaningful change for outcomes.

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Research Grants (2)

Recovery of symptoms, function, tendon structure and mechanical properties in patients with Achilles Tendinopathy: A comparison between men and women.

NIH NIAMS R01 $2,313,323

04/01/2018 - 03/31/2024 The goal of this project is to evaluate the time-course of recovery in terms of tendon structure and viscoelastic properties along with symptoms and muscle-tendon function in 100 men and 100 women with Achilles tendinopathy treated with an exercise program

Neuromuscular Electrical Stimulation for Achilles Tendon Rupture Rehabilitation

NIH NIAMS R21 AR077282 $545,150

05/01/2021 - 04/30/2024 The objective of this study is to develop and evaluate a NMES rehabilitation protocol for surgically-treated Achilles tendon ruptures. This study is divided into two aims. Aim 1 will determine parameters of the NMES protocol based on measurements of tendon mechanical properties. Aim 2 will evaluate the feasibility and preliminary efficacy of NMES protocol as a self-applied intervention.

Accomplishments (7)

Spotlight Speaker, Orthopaedic Research Society Annual Meeting (professional)


Legacy Fund New Investigator Research Grant Award, American Academy of Sports Physical Therapy (professional)


Nominated, UD Midcareer Research Excellence Award (professional)


Selected to attend Faculty Success Bootcamp through National Center for Faculty Development and Diversity (NCFDD) (professional)


Excellence in Research Award, College of Health Sciences, University of Delaware (professional)


IJSPT Best Case Study Award (professional)


EATA Research to Reality Award (professional)


Education (3)

University of Gothenburg: PhD, Medicine (Orthopaedics) 2006

University of Gothenburg: MSc, Physical Therapy 2001

Boston University: BS, Physical Therapy 1990

Affiliations (6)

  • Delaware Tendon Research Group
  • National Athletic Trainers Association
  • European Society of Sports Traumatology, Knee Surgery and Arthroscopy
  • American Physical Therapy Association : National, Delaware Chapter, Orthopaedic, Sports Physical Therapy and Research section (Academy)
  • Orthopaedic Research Society
  • American College of Rheumatology

Languages (1)

  • English

Event Appearances (6)

Spotlight Speaker

(2023) Orthopaedic Research Society Annual Meeting  Dallas, Texas

Achilles tendinopathy treatment and return to sport. Lower extremity tendinopathy: Testing and Evaluation

(2021) Mountain Land Running Summit  Park City, Utah

Non-Operative Management and Post-Operative Rehabilitation

(2021) ISAKOS Webinar on Achilles tendon rupture  Virtual

Current concept in the clinical treatment of tendinopathy

(2020) Team Concept Conference, American Academy of Sports Physical Therapy  Virtual

Use of ultrasound in practice, with a focus on the Achilles, and for research

(2020) AOFAS Allied Health Conference  Virtual

Keynote Lecture: Achilles tendon rupture treatment and expectations for recovery

(2020) La Trobe Sport and Exercise Medicine Research Centre Sports Medicine Student Showcase  Virtual