Cavovarus feet are complex deformities in multiple planes. There is little consensus on the best way to address deformities. Furthermore there are various different phenotypes and we have previously described 4 distinct forefoot morphotypes that exist. It has been hypothesised that the various morphotypes could benefit from differing surgical strategies.

However, identification of forefoot morphotypes has only been possible thus far using specialised semi-automated software and 3D animating software to manually identify morphotypes. It is therefore not straightforward to identify which patients may benefit from which surgery and this is not translatable to surgeons outside of a specialist centre.

The utility of this classification has been thus far limited to research. There is a burning need to explore ways in which identification of forefoot morphotypes can be translated to other centres using techniques such as basic imaging or clinical examination to identify patients with different morphotypes.

At Royal National Orthopaedic Hospital (RNOH) we have a large, complex cohort of patients with neuromuscular foot and ankle deformity and cavovarus feet. We also have access to advanced imaging techniques which we employ in routine care of our patients. We further have access to the software and previous research tools used to identify forefoot morphotypes.

We have for many years been examining cavovarus feet and documenting the various clinical findings. We also run teaching clinics combined with registrars where patients are routinely examined as part of routine care and pre-operative work up.

Therefore we are ideally and uniquely placed to carry out this research which is an extension of our previous work. Our primary aim is to identify a reproducible method of distinguishing between the various forefoot morphotypes in cavovarus feet in patients with Charcot Marie Tooth disease (CMT). This will include investigating the utility of clinical examination and manual measurements (without specialised software) on weightbearing CT (WBCT). We will also aim to examine the reproducibility of any techniques such as clinical examination.

Inclusion Criteria:

• Adult patients aged ≥ 18 years
• Clinical diagnosis of cavovarus foot deformity, AND confirmed Charcot-Marie-Tooth disease or other hereditary sensorimotor neuropathy
• Already under the care of the Foot & Ankle Unit at RNOH.

Additionally, for PROSPECTIVE element:

• Capacity to provide written informed consent

Additionally, for the RETROSPECTIVE element:

• Previously assessed for cavovarus feet at RNOH
• Forefoot morphotype previously identified using Disior Bonelogic software
• Clinical examination findings documented in medical notes.

Exclusion Criteria:

• Previous surgery to the hindfoot or midfoot
• Age under 18 years

For the PROSPECTIVE element:

• Unable to consent

For the RETROSPECTIVE element:

• Participant has previously withdrawn consent for use of their data in line with NHS Opt-out
• Insufficient clinical examination data recorded in medical notes.

Patients with CMT and cavovarus feet