Normative values of ankle strength and its importance for rehabilitation and return to activity: A cross-sectional study.

Abstract

Background

Ankle normative values are limited compared to isokinetic knee assessments. Chronic ankle instability correlates with agonist-antagonist imbalances, decreased evertor/invertor ratio, and plantar flexion deficits. Strengthening programs targeting evertor/invertor and dorsiflexor/plantar flexor balance help reduce injury recurrence. Bilateral neuromuscular deficits compromise the contralateral side, rendering healthy limbs unsuitable as recovery references. Defining normative healthy ankle parameters is crucial for establishing precise limits in non-surgical treatments and sports return criteria. While the limb symmetry index (LSI) is used for knees with a cutoff of > 90%, no such standardization exists for the ankle.

Aim

To comprehensively evaluate isokinetic ankle strength profiles in non-athletic individuals.

Methods

This is a cross-sectional study. Two hundred ankles were evaluated using the Biodex 3 System to assess eversion, inversion, dorsiflexion, and plantar flexion. Healthy individuals with an active lifestyle and no previous injuries were evaluated. The Maximum Torque, Agonist/Antagonist Ratio, LSI, and Muscular Deficiency Index (MDI) and the correlation with demographic variables were evaluated.

Results

The mean age (mean ± SD) was 38.5 ± 13.5 years, and the body mass index (BMI) was 25.8 ± 4.2 in 69 men and 31 women. The mean maximum torque values by gender were (mean ± SD): 22.3 ± 6.6 female (F) and 33.4 ± 9.9 male (M) N/m for eversion; 30.10 ± 10.0 (F) and 37.0 ± 11.6 N/m (M) for inversion, 37.4 ± 10.0 (F) and 53.6 ± 13.0 N/m (M) for dorsiflexion, and 100.4 ± 37.2 (F) and 158.1 ± 33.4 (M) N/m for flexion. There was no correlation between age or BMI and maximum torque. The evertors/invertors ratio was 88.8%, and the dorsiflexors/plantar flexors ratio was 36.1%. The MDI and LSI were balanced between sides for every movement, having an average global difference of less than 10%.

Conclusion

These findings provide gender-specific normative isokinetic values for the ankle in healthy, physically active adults. These reference parameters-especially LSI and MDI above 90%-can support clinical decision-making in rehabilitation planning and return-to-sport assessment, offering objective benchmarks for functional recovery.

Department

Description

Provenance

Subjects

Ankle ligament injuries, Ankle tendinopathies, Dynamometry, Isokinetic strength, Isokinetics

Citation

Published Version (Please cite this version)

10.5312/wjo.v16.i10.108858

Publication Info

da Fonseca, Lucas Furtado, Madhan Jeyaraman, Naveen Jeyaraman, Thiago Resende Inojossa, Eduardo Souza Maciel, Cesar de Cesar Netto, Nacime Salomão Mansur, Diego Costa Astur, et al. (2025). Normative values of ankle strength and its importance for rehabilitation and return to activity: A cross-sectional study. World journal of orthopedics, 16(10). p. 108858. 10.5312/wjo.v16.i10.108858 Retrieved from https://hdl.handle.net/10161/33751.

This is constructed from limited available data and may be imprecise. To cite this article, please review & use the official citation provided by the journal.

Scholars@Duke

de Cesar Netto

Cesar de Cesar Netto

Associate Professor of Orthopaedic Surgery

The desire to explore, research, and understand things in great detail has been the driving force throughout my career. This passion drew me to Foot and Ankle, a subspecialty expanding in orthopedic knowledge with many unsolved mysteries. After completing my Medical School, Orthopedic Residency, and Foot and Ankle Fellowship at the renowned University of Sao Paulo, ranked number one in Latin America for several years, and after five years of clinical practice in Brazil, this desire to explore and understand also brought me to the United States. As part of my Ph.D. program with the University of Sao Paulo, I joined as a visiting scientist and research fellow for Dr. Lew Schon at the traditional MedStar Union Memorial Hospital in Baltimore-MD, where I developed an animal model of induced Achilles tendinopathy. 

As a practicing physician in Brazil, I achieved multiple goals in my early career. Academics have been a large component of my practice, allowing me to participate in young physicians' education and challenge my understanding of orthopedic fundamentals. As the elected Chief of Orthopaedic Residents from 2011 to 2013, I presented 245 lectures to orthopedic surgeons and in multidisciplinary conferences. My practice as an orthopedic surgeon in Sao Paulo allowed me to combine the Brazilian enthusiasm for soccer, serving as the team physician and Foot and Ankle advisor for the professional soccer team Sport Club Corinthians Paulista for almost five years.

As a Foot and Ankle surgeon, I constantly sought to confront the unsolved questions in our orthopedic practices. During my Ph.D. studies with the University of Sao Paulo, I aimed to maximize my research experience and clinical exposure. During my time in Maryland, I have engaged in multiple research projects, collaborating with MedStar Union Memorial and Johns Hopkins University to evaluate and clinically implement innovative imaging techniques, including weight-bearing CT, dynamic CT, 3D MRI, and metal artifact reduction sequence (MARS) MRI.

I was also amazed by the American medical system's resources that create opportunities for motivated physicians to excel in clinical work, educational teaching endeavors, and research investigations. While this balance requires dedication and precise time management, I have been fortunate to work with a variety of mentors who demonstrated to me how great it could be to practice in the US. With that in mind, I ended up deciding to pursue the Academic Pathway of the ABOS Certification. I have completed a total of three Orthopedic Foot and Ankle Fellowships in the US. The first was at the University of Alabama at Birmingham (UAB), the second at the Hospital for Special Surgery (HSS) in New York City, and the third and final at MedStar Union Memorial Hospital in Baltimore-MD. It was a long but very pleasant and rewarding pathway that allowed me to grow as a person, as a clinician, and as a surgeon while being fortunate to create lifetime bonds with several mentors. Once I was done with my fellowships, my objective was to combine my unique background with my innovative and instructive training and apply the acquired knowledge as an Academic Assistant Professor at the Department of Orthopedics of the Carver College of Medicine at the University of Iowa.

The almost four years in Iowa City have been a blast! The leadership of the Orthopedic Department entirely and constantly supported me, and together, we achieved a lot in a relatively short amount of time. I utilized my academic start-up grant to acquire the first Weight-Bearing CT scanner in the Country that allows the hip, knee, foot, and ankle to be scanned under load simultaneously. With the scanner, I founded and served as the Director of the University of Iowa Orthopedic Functional Imaging Research Laboratory (OFIRL), which rapidly achieved an established, recognized position in the research and orthopedic foot and ankle community. I also had the unique opportunity to care for the State of Iowa community suffering from orthopedic foot and ankle problems, always excelling in providing high-quality and passionate clinical and surgical care. I’ll be forever grateful to my leadership, partners, and colleagues in Iowa City, as well as my patients, who gave me the utmost opportunity to care for them.

As an Associate Professor in the Department of Orthopedics at Duke University, I hope to contribute further to the American society and North Carolina Community, taking excellent care of patients, teaching and mentoring medical students, residents, and fellows, and helping the orthopedic foot and ankle surgery research to excel.


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