Cesar de Cesar Netto

Dr. de Cesar Netto's research program studies the foot and ankle under physiologic load. It uses weightbearing CT (WBCT), three-dimensional analysis and enabling technologies to understand, classify and correct complex deformity and instability. Three connected areas have defined the work: weightbearing CT as a research and clinical platform, progressive collapsing foot deformity (PCFD), and multidirectional ankle instability. Of his more than 310 peer-reviewed publications, about 80 involve weightbearing CT and more than 70 address flatfoot or PCFD.

 

Weightbearing CT: building the platform

His work with WBCT began during his research years in Baltimore. It became one of the first bodies of evidence for the technology in foot and ankle surgery.

• Load changes the picture (2017). His JBJS paper compared weightbearing and non-weightbearing cone beam CT in flexible adult-acquired flatfoot. It showed that conventional supine imaging underestimates the deformity.
• Building the community (2016 onward). He helped found the Weightbearing CT International Study Group, which became the International Weight Bearing CT Society. He served as its Secretary, Treasurer, Vice President and President.
• Reliability (2019). He published early reliability work showing how investigator experience affects WBCT measurements.
• Foot and Ankle Offset (2020). His group introduced Foot and Ankle Offset (Foot Ankle Int), a semi-automatic, multiplanar measure of overall hindfoot alignment. It is now widely used in WBCT research.
• Textbook (2020). He co-edited the first textbook dedicated to WBCT in the foot and ankle (Springer). He also co-authored the 13,000-scan analysis of WBCT's effect on cost, radiation and time.
• Three-dimensional distance and coverage mapping (2021 onward). This moved the field beyond two-dimensional angles. The maps quantify joint congruency and subluxation across the whole articular surface, first at the subtalar joint (Foot Ankle Int 2021) and then at the Chopart joint (Sci Rep 2022).
• Automation and planning (2025 to 2026). More recent work focuses on automation and surgical planning at the Duke GRAV-ET Lab. Examples include automated versus manual measurement and the Subtalar Joint Offset (Foot Ankle Int 2025). The lab has also developed WBCT-based predictive surgical planning (J Foot Ankle Surg 2026), virtual osteotomy simulation and 3D printing for classification.

 

Progressive collapsing foot deformity: from observation to classification to outcomes

The PCFD work follows a clear sequence. Each step builds on the one before it.

1. Combining imaging (2018 to 2021). Combined WBCT and MRI assessment of flexible flatfoot asked which patients were at risk of collapse. This work won the Best Research Project award at FLAMECIPP 2018 and Distinguished Research at EFAS 2018, and was published in Foot Ankle Surg in 2021.
2. Identifying the key marker (2019 to 2020). His JBJS 2019 case-control study identified middle facet subluxation of the subtalar joint as a marker of peritalar subluxation. A 2020 follow-up in Foot Ankle Int compared the posterior and middle facets and found the middle facet to be the earlier sign. This made middle facet subluxation a central measurement in the field.
3. Renaming and reclassifying the disease (2019 to 2020). He organized and chaired the expert consensus meeting at the Hospital for Special Surgery in November 2019. The group published its work as a nine-paper series in Foot Ankle Int in 2020. The series replaced "adult-acquired flatfoot deformity" with "progressive collapsing foot deformity" and introduced the five-class PCFD classification. It also set consensus indications for WBCT, osteotomies, fusions and ligament reconstruction. Dr. de Cesar Netto was senior author of the classification paper and first author of the WBCT consensus.
4. Validating the classification (2022 to 2026). His group and others then tested the classification:
   • reliability (Foot Ankle Int 2022)
   • diagnostic accuracy (Foot Ankle Int 2022)
   • the effect of WBCT on classification (Foot Ankle Int 2023)
   • radiographic threshold values for each class in a large cohort (Foot Ankle Int 2026)
5. Mapping the deformity in 3D (2021 to 2024). Distance and coverage maps showed peritalar subluxation in three dimensions. Related studies examined the Chopart joint, ankle and syndesmotic changes, lateral impingement, and the transverse arch.
6. Linking anatomy to symptoms and outcomes (2023 to 2025). In 2023 (Foot Ankle Int) he showed that correcting peritalar subluxation improves patient-reported outcomes; this work was named an AAOS Top Paper in Foot and Ankle. His JBJS 2025 paper compared asymptomatic flatfeet with symptomatic PCFD. It established peritalar subluxation as the main driver of symptoms.
7. Toward precision treatment (2025 to 2026). Current work covers:
   • predictive WBCT surgical planning, supported by an AOFAS grant
   • a novel interosseous talocalcaneal ligament reconstruction technique (J Foot Ankle Surg 2025)
   • subtalar joint dynamics across disease progression, and predictors of failed conservative treatment (Foot Ankle Surg 2026)
   The 2026 AOFAS J. Leonard Goldner Award recognized his cadaveric study of combined interosseous talocalcaneal and spring ligament reconstruction. The study used simulated walking.

He reconvened the PCFD consensus group in April 2025 to update the framework with the evidence gathered since 2020.

 

Multidirectional ankle instability

This area grew out of his syndesmosis research. It challenges the traditional view of ankle sprains as isolated lateral injuries.

• Syndesmotic instability in surgery (2018 to 2021). Cadaveric studies tested intraoperative assessment of syndesmotic instability. They introduced the tap test (Injury 2018) and compared it with the Cotton test (Injury 2021).
• The medial side (2021). A review of chronic medial (deltoid) ankle instability in Foot Ankle Clin drew attention to the medial ligaments.
• Detecting subtle instability with 3D mapping (2022 to 2025). A WBCT distance mapping pilot study (J Foot Ankle 2022) led to his cadaveric diagnostic study in JBJS 2025. That study showed 3D WBCT distance mapping can detect subtle syndesmotic instability that standard measurements miss. It won Best Research Study at the FLAMECIPP Triennial Meeting in 2023. Normal values for the syndesmotic space with and without external rotation stress followed in Foot Ankle Int in 2024.
• Defining the concept (2023). With Victor Valderrabano, he defined multidirectional chronic ankle instability (Foot Ankle Clin 2023). This is the combined involvement of the lateral, medial and syndesmotic ligaments after rotational injury.
• Clinical evidence (2026). A prospective cohort (Foot Ankle Surg 2026) documented combined multiligament instability in patients with chronic symptoms after rotational ankle injuries. Collaborative work on adding deltoid and syndesmotic reconstruction to the Broström procedure followed (Foot Ankle Orthop 2026).
• Automated detection (2024 to 2026). Automated, contralateral-referenced 3D analysis continues this work and has been recognized several times:
  • the 2024 AOFAS Goldner Award for a mentee-led study
  • the ORS New Investigator Recognition Award in 2022 and 2026
  • the 2026 AOFAS Robert Anderson Award, for showing that apparent syndesmotic widening is an unreliable sign of true fibular instability

An Arthrex investigator-initiated grant (2026 to 2027) now supports WBCT evaluation of isolated and combined deltoid injuries. The topic is also a frequent subject of his invited lectures and visiting professorships, including at the University of São Paulo (2024) and the Rizzoli Institute in Bologna (2025). It connects directly to his role at the FIFA Medical Centre of Excellence at Duke.

 

Unifying theme

Across all three areas, the program follows the same path. It first establishes that weightbearing, three-dimensional imaging reveals what conventional methods miss. It then turns those findings into validated measurements and classifications, and finally links them to patient outcomes and surgical decisions.