I'm Luke Johnson

I live and work in Vancouver, BC
I write about research and other interests here


Fediverse usability: Lemmy/Mbin/PieFed communities on Mastodon

Back in the day, I used to spend a lot of time on Reddit. I still skim through the top posts on certain subreddits from time to time, but the site has now been sliding down the inevitable and crudely-named ensh*ttification spiral for some time. As with most social media platforms, there are alternatives on the Fediverse: platforms like Lemmy, Mbin and PieFed. These are formatted like Reddit: each page has a list of posts ordered using an algorithm that takes into account both recency and popularity (based on upvotes and downvotes). Clicking on each post will take you to that post’s comments, arranged in a similar way.

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Research summary: cartilage health after Perthes’ disease

That’s right, you get two summaries for the price of one this month. By a quirk of the peer review process and copyediting timeline, two of my PhD thesis chapters were published as journal articles within a week of each other! See here for my summary of the other one.

The article summarised here investigates the role of Perthes’ disease—a condition which can cause a permanent change to the shape of the hip joint (deformity) during childhood—in how cartilage health changes during adolescence and young adulthood. The full text is available open access in Osteoarthritis and Cartilage Open as:

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Research summary: Perthes’ disease and hip impingement

Changes to the shape of the hip joint caused by Perthes’ disease are linked to problems such as hip pain and arthritis later in life. But how exactly does deformity result in bad outcomes? One part of my PhD thesis looked into this question, and is available open access in the Journal of Pediatric Orthopaedics as:

Johnson LG, Zhang H, Joseph B, et al. 2025. Anterior hip clearance in residual Legg-Calvé-Perthes disease. J Pediatr Orthop.

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100 Block Rock

Another favourite illustration I produced for Discorder magazine is the very first one I contributed—way back in January 2021! Accompanying a review for “100 Block Rock”, a compliation album of music by artists based in Vancouver’s Downtown Eastside (DTES), this assignment really gave me a chance to explore some themes of hope and community based on the album’s lyrics.

A circular frame incorporates a red outline, black triangular motifs, and compass directions starting with north to the right. Inside the frame is a graphic of a centred heart in red atop a pillar, flanked by a mint green leaf and black-outlined feather. Curved claws protrude from the heart as if it is the palm of a bear's paw. Mint green embellishments fit in the square corners outside the frame. Many of the outlines and details are filled with tiny song lyrics.

The cover image for “100 Block Rock”, based on a sidewalk mosaic at Hastings and Main

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Dr Luke Johnson, PhD

This will take some getting used to…

This will take some getting used to…

Yesterday afternoon, I successfully defended my PhD Thesis: Advanced MR Imaging and Modelling of Legg–Calvé–Perthes Disease. It was a much more pleasant experience than I expected/feared, but this might be down to luck. All of my examiners were very kind and supportive, which isn’t always the case.

Everybody approaches their oral defence differently. Some people spend the time making sure they could answer any potential question, but my approach in the lead-up was to make sure I was well-rested and relaxed. I think it worked! There is one piece of advice I received that I shall pass on: make sure you decide in advance what you are going to wear. Having one fewer thing to think about as you prepare on the day is invaluable.

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Two Website Updates

As I write this, my PhD defence is in less than 48 hours’ time! This last weekend I wanted to make sure I relaxed properly, so to avoid psyching myself out with intrusive thoughts I’ve been doing some housekeeping with the website for usability and adaptiveness. I then added a comments feature as well for good measure.

Housekeeping

The main update here was to tidy up dark mode. Previously it was a bit of a mess; some text and other elements would switch to light colours, but the background would stay light. No more! It should be working nicely and more easily on the eyes now.

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Elevator Music

A cartoon-style elevator scene framed by the opened doors. The environment and a pair of men in business suits are depicted with little detail and in greyscale. A young woman with an afro is centred facing the viewer with her eyes closed in contentment. She is wearing headphones and apparently levitating about six inches off the ground, while around her head an imagined scene of colourful clouds fills the elevator.

Every so often here at UBC (about twice a year) I’ve contributed illustrations to Discorder magazine, the print wing of the student radio station CiTR. I’ll be the first to admit my illustration skills are hit and miss at best—it’s a good thing I don’t get paid—but I was digging through old files and realized I’d never really shared them. That’s about to change!

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Research summary: shape analysis of Perthes’ disease deformity

This post is a summary of recent work in collaboration with Prof Andrew Anderson and Dr Joseph Mozingo at the University of Utah, and Dr Harry Kim at the Texas Scottish Rite Hospital for Children. It was recently published in the International Journal of Computer-Assisted Radiology and Surgery as:

Johnson LG, Mozingo JD, Atkins PR, et al. 2024. A framework for three-dimensional statistical shape modeling of the proximal femur in Legg–Calvé–Perthes disease. Int J Comput Assist Radiol Surg.

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View from above

A photograph of Vancouver taken from Mount Seymour at sunset. The city is partially obscured by thin, snow-covered trees.

View of Vancouver from the Mount Seymour ski area, taken in February 2023. UBC is behind the middle tree, on the furthest peninsula.

Research posts: the plan

I don’t want to mix my work and research updates in with the eclectic “blog” posts, so they have their own section on this site. Here’s the plan: over the next days and weeks I’ll post lay summaries of my past publications and conference abstracts.

Hopefully I can then keep this going every time I have something new to share, be it a new paper, conference blog, career update and so on.

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