PhD: Foot Biomechanics for the Next Generation of Total Ankle Replacement

PhD: Foot Biomechanics for the Next Generation of Total Ankle Replacement

Research cut-off: 6 November 2026
Institution: Cardiff University, Cardiff School of Engineering
Application details in the project information: deadline 5 January 2027; planned start October 2027; advertised duration 3.5 years full-time or part-time equivalent.

Quick Decision

This is a focused biomechanics doctorate for work at the boundary of orthopaedic engineering, dynamic imaging and computational modelling. The stated doctoral question is how the midfoot adapts when ankle function is altered by end-stage ankle osteoarthritis or total ankle replacement (TAR), and how those adaptations relate to loading around the foot and implant. Cardiff's human movement and biplanar X-ray resources, the named staff's imaging/biomechanics profiles, and the wider EASE-ankle OA consortium form the strongest documented research assets.

The project information describes the studentship as fully funded and gives reference CH DLA 27, a 3.5-year duration, an October 2027 start and a 5 January 2027 deadline. The exact funding body, stipend, fee coverage and international-student conditions were not confirmed in an accessible Cardiff project-specific award page. EASE's £12m EPSRC programme grant supports a research collaboration; that grant alone does not establish the student's award terms. The next useful step is to obtain the written studentship terms and ask the named academics about the cohort, imaging protocol and supervision split.

The research could add mechanistic evidence about foot-bone motion and loading. It should not be read as a clinical trial or as a promise that a particular implant, operation or rehabilitation strategy will improve patient outcomes. Recent TAR imaging studies are small, and one-year randomized evidence has not established overall superiority of TAR over ankle fusion.

Research Problem and Doctoral Work

What is unsolved and why it matters

The project information describes end-stage ankle osteoarthritis as a cause of pain and reduced mobility, and frames TAR as an alternative to ankle fusion that aims to preserve motion. The research question moves beyond the replaced ankle itself: it asks how the midfoot responds when ankle mechanics change and whether those responses are associated with joint loading and the implant's mechanical environment.

Clinical evidence gives important boundaries to that question. The UK TARVA randomized trial allocated 303 participants aged 50–85 years with end-stage ankle osteoarthritis to TAR or fusion. At 52 weeks, both groups had improved, but the trial did not show a statistically significant overall difference in its primary walking/standing outcome; the authors describe the result as inconclusive for TAR superiority. The trial's follow-up, implant/technique heterogeneity and patient eligibility limit what it can say about long-term performance or individual subgroups. The TARVA trial report therefore supports careful comparison, not a claim that one procedure is clinically better for every patient.

The National Joint Registry 2026 executive summary reports an overall 10-year cumulative revision estimate of about 9.5% for ankle replacements. It cautions that the figure is likely a modest underestimate because some ankle revisions may not be captured, and that implant-level outcomes vary. Registry revision is a population-level endpoint; it does not measure the midfoot mechanics proposed here. The AAOS 2026 ankle osteoarthritis guideline is clinical guidance for ankle OA management, not validation of any particular imaging or modelling hypothesis.

Work, methods and potential outputs

The project information advertises four connected tasks: measure midfoot compensation in people with ankle OA and after TAR; combine biplanar videoradiography (BVR)/dynamic X-ray with gait analysis; use subject-specific computational modelling; and investigate associations with joint loading and the mechanical environment experienced by ankle implants. The project presents these findings as evidence that may inform future implant design and rehabilitation. That is a prospective contribution, not a guaranteed design change or clinical benefit.

The project description states that Cardiff's BVR facility can measure three-dimensional motion of individual foot bones during functional activity with sub-millimetre accuracy. Cardiff's official facility pages independently confirm a high-speed, bespoke biplanar X-ray laboratory integrated with movement analysis, plus force platforms, electromyography, treadmill and related human-movement equipment. The facility's public descriptions do not independently quantify the project's sub-millimetre accuracy claim. Cardiff's Medical Engineering Research Group also lists a MicroCT room and clinical assessment space; MRI access is stated in the project information and should be confirmed for this study.

Recent original research illustrates both the opportunity and the limits:

• A 2025 bi-plane fluoroscopy study compared 11 TAR patients with 11 participants with natural ankles. It reported physiological movement patterns after TAR but significantly reduced range of motion; in deep-squat and kneeling positions, measured angles were 30–40% of the natural-ankle group. This is Level IV evidence from a small, specific cohort, not a result for every implant or patient. See Mikami et al. (2025).
• A 2024 videofluoroscopic feasibility study analyzed eight postoperative participants, five with fixed-bearing and three with mobile-bearing implants. It found no significant group difference in measured tibiotalar motion during gait, but explicitly described the work as underpowered. It shows feasibility more than design equivalence. See Abbott et al. (2024).
• A 2023 dynamic finite-element study compared intact, total talar replacement and TAR conditions using one healthy participant's MRI and gait data. Its model suggested implant-related changes in ankle motion and force transmission through the midfoot. The single-subject geometry and modelling assumptions make this hypothesis-generating evidence, not patient-outcome evidence. See Chen et al. (2023).
• A 2024 4D-CT and modelling study measured 12 healthy participants during a standardized simulated stance phase and used four post-fracture cases as clinical comparisons. It demonstrates a possible way to combine observed kinematics with estimated internal contact mechanics; it did not study TAR patients. See Postolka et al. (2024).
• A 2024 study using three cadaveric feet proposed four kinematic synergies to describe ankle and foot-bone coupling. Its compact model supports the premise that foot motion is coordinated, but the small in-vitro sample and controlled postures do not represent dynamic movement after TAR. See Conconi et al. (2024).
• A validation study of 10 healthy volunteers compared a four-segment optical foot model with bi-planar X-ray radiostereometric tracking during walking. Agreement varied by measure and plane. It helps define what conventional movement capture can estimate, but is not a post-TAR validation. See Valevicius et al. (2024).

Taken together, these studies make the advertised combination of bone-level imaging, whole-foot movement and modelling scientifically relevant. The specific patient groups, number of participants, functional tasks, clinical measures, model validation strategy and link to implant outcomes are not stated. Potential angles such as comparing groups or testing whether movement measures explain load estimates should be treated as questions for the supervisors, not as confirmed work packages.

School, Programme and Field Context

The PhD is advertised through Cardiff School of Engineering, with Cardiff University as the degree institution. The project's wider research collaboration is Engineering Advanced Solutions for End-stage Ankle Osteoarthritis (EASE-ankle OA), a five-year, £12m EPSRC programme led by the University of Sheffield and involving Cardiff, Leeds, Birmingham and Warwick, plus NHS, industrial and international partners. Participation in that consortium does not establish a joint or double degree; the application instructions specify Doctor of Philosophy (Engineering) at Cardiff.

Cardiff's current rankings page lists QS World University Rankings at =179 for 2027, ARWU at 201–300 for 2026, and THE World University Rankings at 201–250 for 2026. These are overall institutional rankings, not a ranking of biomedical engineering, orthopaedics or ankle biomechanics. In REF 2021 Unit of Assessment 12 (Engineering), Cardiff reports an overall GPA of 3.35, with 40% of the assessed activity at four-star and 56% at three-star. This broad engineering assessment gives research-context evidence but cannot predict this project's supervision or outcomes; see Cardiff's REF Engineering results.

The Engineering research degree page describes a standard full-time PhD as three years and a part-time route as five to seven years; doctoral researchers have at least two qualified academic supervisors, annual progress review and approved research training. The project information instead advertises 3.5 years. These may refer to a project-specific funded period rather than a different award, but the relationship between registration, funding and writing-up time should be confirmed. The stated start month, October 2027, is one of Cardiff's listed research-degree start dates. The programme page gives IELTS 6.5 overall with at least 5.5 in each subskill, or an accepted alternative.

Supervisor and Lab Assessment

Professor Cathy Holt is Professor of Biomechanics and Orthopaedic Engineering, directs the Musculoskeletal Biomechanics Research Facility (MSKBRF), and is available for postgraduate supervision. Cardiff describes her research in 3D motion analysis, orthopaedic biomechanics and functional classification of joint disease and surgical intervention; her profile reports leadership or collaboration on programmes attracting more than £25m in external funding. These are relevant experience signals, not evidence of a guaranteed supervision arrangement. See the Cardiff profile for Professor Cathy Holt.

Dr David Williams leads in-vivo imaging research at MSKBRF and combines advanced imaging, musculoskeletal biomechanics and computational modelling. His profile lists the Open-Source Computational Ankle Model (OSCAM) as an active project and says he is available for postgraduate supervision. The project information invites discussion with Dr Williams or Prof Holt and identifies Prof C. A. Holt in the contact field; it does not specify a formal lead/co-supervisor split. See the Cardiff profile for Dr David Williams.

Cardiff's Medical Engineering Research Group reports that MSKBRF opened in 2017 as a Cardiff University/Welsh Government jointly funded initiative. Its facilities include a clinical movement laboratory, motion-capture cameras, force plates, surface EMG, instrumented stairs and treadmill, and a bespoke pulsed biplanar X-ray system. The university's MSKBRF page describes synchronized motion analysis and biplanar fluoroscopy; its equipment inventory lists high-speed imaging and additional tools. These resources fit the advertised measurements. Actual access, protocol readiness, staff support, MRI availability and use of NHS clinical space remain study-specific questions.

The named team also has recent work relevant to method and measurement. Dr Williams's Cardiff profile lists a 2026 paper, “Less is more: downsampling X-ray images improves pose estimation accuracy”, and a 2025 co-authored article on standardizing 3D foot and ankle imaging measurements. The former signals ongoing X-ray processing work; the latter is a measurement-standardization review, not a primary clinical TAR study. The field papers above therefore help contextualize the proposed work, while the public profiles do not establish that the Cardiff group has already validated this exact post-TAR midfoot protocol.

Funding, Application and Living Cost

The project information describes full funding and gives CH DLA 27 as the application reference, but does not state the stipend amount, fee amount, budget for research/training, or award terms. The EASE programme grant is a separate research award: its published £12m amount should not be interpreted as the amount or contractual coverage of this studentship. The key question is which scheme funds this position and what is included over the advertised 3.5 years.

Cardiff's general funded doctoral-centre information says international students holding a UKRI studentship receive a fee discount so they are not charged the home/international fee difference. Cardiff's EPSRC studentship page likewise describes full funding and fee discounts, while noting that international places are capped. These are general policies; they do not confirm that CH DLA 27 is a qualifying EPSRC/UKRI award or that this specific place is open to every fee status. UKRI's training grant guidance lists a 2026/27 full-time minimum stipend of £21,805 and a fee level of £5,238. The October 2027 stipend rate had not been set at the 6 November 2026 research cut-off.

Cardiff's research-fee page, at the time reviewed, still displayed a 2025/26 annual fee schedule for science-based postgraduate research of £5,006 for UK students and £26,700 for international students and said that it would be updated. Those historical figures are not a reliable fee forecast for October 2027; see Cardiff postgraduate research fees. The project award letter, if offered, is more important than this old schedule.

Cardiff's 2026/27 living-cost calculator estimates £13,510.92 for 52 weeks in a private four-bedroom shared house, including £500 per month rent before bills. The estimated postgraduate university-hall budget is £16,835.78 per 52 weeks. The private-share estimate is £8,294.08 below the current £21,805 UKRI minimum when compared mechanically; this is not an award projection or guaranteed disposable balance. It excludes future inflation and individual variation, and visa, relocation, travel or other one-off expenses may apply. Confirm which items the studentship separately pays.

The project details give a 5 January 2027 application deadline and October 2027 start. The specified route is a Cardiff PhD in Engineering application, with CV, statement/cover letter, two references and transcripts; applicants are told to identify the project and supervisors and use reference CH DLA 27 in the funding section. Check the live Cardiff Engineering application page for any updated steps. Cardiff's institutional information page confirms the university is based in Cardiff, Wales, United Kingdom.

Applicant Fit and Preparation

The stated academic routes are a first-class or good 2:1 degree (or equivalent) in Engineering, or an MSc/MEng in Mechanical Engineering, Biomedical Engineering, Computer Science or another relevant area. Musculoskeletal biomechanics knowledge is desired. Laboratory or field experience, MATLAB/Python coding and interest in applying technology to joint-function research are described as advantages, not mandatory entry conditions.

A strong application should make the quantitative preparation legible: relevant mechanics, programming, imaging/data analysis, experimental design or human-movement projects; what was personally done; and how uncertainty or measurement error was handled. Applicants without prior foot biomechanics may explain how they would bridge their existing engineering/computing background to clinical movement research. These are preparation suggestions inferred from the advertised work, not additional admission requirements.

The opportunity says applicants whose first language is not English need IELTS 6.5 or equivalent; Cardiff's programme page specifies the 5.5-per-subskill rule. Confirm the accepted evidence and any exemptions for the 2027 cohort. The project details list CV, personal statement or covering letter, two references and current transcripts. Because the project is defined, the application instruction is to identify its title and supervisors in the proposal area rather than invent a separate doctoral question.

Career directions described by the training plan include academia, healthcare technology and industry. Plausible adjacent roles include musculoskeletal biomechanics research, medical imaging and motion-analysis development, computational biomechanics, orthopaedic-device research and clinical engineering. EngineeringUK's 2026 update, using 2025 Labour Force Survey data, reports 6.3 million people in UK engineering and technology roles—about 19% of UK jobs. This is broad sector context, not a forecast for foot-biomechanics jobs or project graduates, and no alumni placement data was found. See EngineeringUK's workforce update.

Next Actions and Questions to Verify

Before applying

1. Ask Cardiff and the named academics to identify the funder and formal scheme behind CH DLA 27, the annual stipend, fee coverage, international fee-difference policy and research/training allowance.
2. Confirm that international applicants are eligible for this exact award, whether the award pays the full fee for their fee status, and which costs such as visa, healthcare surcharge or relocation are outside it.
3. Confirm the 5 January 2027 deadline, October 2027 start, 3.5 years of funding, and how these relate to Cardiff's standard Engineering PhD registration length.
4. Ask whether IELTS 6.5 requires 5.5 in each subskill and which equivalent tests or exemptions apply.

At interview

1. Ask which participant groups are planned—ankle OA, post-TAR, healthy comparison or other—and the expected sample size, recruitment route and clinical outcome measures.
2. Clarify the movement tasks, BVR/MRI availability, imaging dose and participant burden, and whether the core protocol already has ethics, NHS and radiation-governance approvals.
3. Ask how measured bone motion, gait measures and subject-specific models will be combined and validated before drawing conclusions about joint loading or implant environment.
4. Confirm the primary and secondary supervisors, the role of clinical collaborators, meeting arrangements and how Cardiff/EASE partner interactions work.

Before accepting

Obtain the award terms in writing, including funded months, fee status coverage, stipend, extension arrangements, research allowance and what happens if clinical recruitment or data collection takes longer than planned. Treat future stipend rates and current living-cost estimates as planning references only.

Evidence and Sources

Project, consortium, university and training

• University of Sheffield: EASE-ankle OA programme and £12m EPSRC award
• Cardiff Medical Engineering Research Group
• Cardiff MSKBRF
• Cardiff MSKBRF equipment inventory
• Professor Cathy Holt: Cardiff profile
• Dr David Williams: Cardiff profile
• Cardiff Engineering postgraduate research programme
• Cardiff University rankings
• Cardiff REF 2021 Engineering results
• Cardiff institutional location and facts

Clinical evidence and recent research

• TARVA randomized trial
• National Joint Registry 2026 executive summary
• AAOS ankle osteoarthritis clinical practice guideline
• Mikami et al. (2025), in-vivo TAR kinematics
• Abbott et al. (2024), fixed-bearing versus mobile-bearing motion
• Chen et al. (2023), foot finite-element comparison
• Conconi et al. (2024), foot/ankle kinematic coupling
• Postolka et al. (2024), hindfoot imaging and modelling
• Valevicius et al. (2024), multi-segment foot model validation
• Williams et al. (2026), X-ray pose-estimation methods
• Kruger et al. (2025), 3D foot/ankle measurement standardization

Funding, fees, living cost and careers

• Cardiff funded doctoral-centre information
• Cardiff EPSRC studentships
• UKRI training grant holder guidance
• Cardiff postgraduate research fees
• Cardiff living-cost calculator
• EngineeringUK engineering and technology workforce update