There's a lot that's high-tech about joint replacement surgery these days.
But there's also a lot of drilling, scraping, sawing and hammering.
"In some ways, it's a lot like carpentry," Dr Ju Zhang says.
It's certainly not the sort of procedure you want to repeat unnecessarily, but Zhang says in the past 20 years in New Zealand, nearly one in 10 hip replacements have been revisions and one in five knee replacements are unsatisfactory.
In 2016, the Chinese-born Kiwi created Formus Labs to help increase the success rate.
"Joint replacement surgery has never been an exact science, so a relatively high number of surgeries require revision, which hugely impacts a patient's life," he says.
Until now, there hasn't been the technology to accurately predict and model what every patient's new joint should look like for their unique body and needs, meaning people sometimes had a poorly fitted joint.
"X-Rays and CT scans show the body as-is and from there educated guesses determine the size and type of replacement joint to be used."
A key issue is that there are many different sizes of replacement parts - and the right stem has to be put into the right-sized socket and, importantly, at the right inclination. Zhang has calculated that for a hip replacement, there are 11,000 different combinations of prosthetic implants and placement options.
Zhang, who has sat in on dozens of surgeries during the process of developing his product, says a surgeon's experience has been the main factor for selecting the right size implant, at the right inclination. He says it's usual for a sales rep from a prosthetics supplier to be on hand during the surgery with a large number of different balls and stems.
Formus' software uses 3D modelling and AI to help an orthopaedic surgeon select the right combination of ball and stem, and insert it at the right inclination.
The surgeon still makes the final choice, but the aim is to cut it down to a small number of options.
Zhang says through more accurate prosthetic selection, and general workflow and efficiency improvements, his product could save the NZ health system around $15m per year.
The startup was born out of Zhang's studies at Auckland University, where he gained a PhD in 2013 in bioengineering and for "Development of an automatic pipeline for building a large-population statistical model of human femur morphology".
Zhang's parents, who came to New Zealand when he was a young child, had their hearts set on him becoming a doctor, but his first love was engineering. They reached a happy compromise in the middle when Zhang discovered the field of biomedical engineering.
His co-founders were two Auckland University academics, Professor Thor Besier, who set up Stanford University's Human Performance Lab, and Associate Professor Justin Fernandez and software engineer Antonije Velevski.
Formus Labs gained backing from Auckland University's commercialisation arm, Uniservices, plus Cure Kids Ventures, the Crown angel investment agency now known as NZ Growth Capital Partners, and several US venture capital investors - raising around $2 million all up as its product went through development, testing, then key ISO 13485 certification - a medical standard recognised by the FDA in the US and regulators in other major markets.
Ten staff have been hired along the way, and medical heavyweights added to the board like Nicholas Giori, an orthopedics professor at Stanford and chief of orthopedic surgery at Veterans Affairs Hospital in Palo Alto (aka the middle of Silicon Valley), and Oxford lecturer in orthopedic surgery Paul Monk, who is currently with Auckland's UniSports.
Ex-Apple man helps out
The medical academics were joined by Vignesh Kumar, an Aucklander who went to the US as a Fulbright Scholar, worked for Apple in Cupertino as an engineering project manager before returning to NZ in 2018 to set himself up as a tech investor, director and startup adviser (it was Kumar who first dragged the mild-mannered Zhang into the Herald's office).
Clinical development of Formus Labs' product has been assisted by surgeons in NZ, Australia and the US, who have used it in some 200 surgeries during clinical trials.
And the startup was recently qualified as an approved supplier for Zimmer Biomet - the US$8 billion annual revenue, NYSE-listed giant that controls around 40 per cent of the device market for hip and knee replacements
Now, on the eve of Formus' commercial launch in New Zealand and Australia (a "soft launch" is planned for the first quarter of next year), Zhang says the company will look to raise US$5m ($6.7m) in a Series A round.
Some of the funds will be used for a push into the North American market.
But Zhang is also keen to further develop a new product, Formus Spine - "an AI-driven automated planning platform for spinal fusion surgery" that was demonstrated at the New Zealand Orthopaedic Association conference held in Wellington during October.
He also wants Formus Labs' software to be used not just in pre-operation planning, but inside the operating theatre. This will require more software development and machine-learning smarts of course, but Zhang thinks his real secret sauce is that after sitting in on so many operations, he knows how orthopedic surgeons think.
And he also points out that his company's product is now keenly required.
Our ageing population is already putting pressure on the system.
Now Covid-19 has created a huge backlog of elective surgeries n NZ and worldwide, including orthopedic procedures. Pre-operative planning software can help streamline the preparation, provision, and delivery of the backlog of joint replacements.
Although Zhang has global ambitions, Formus Labs is, for now, based at Cloud 9 - a collective of 13 companies that are independent, but based in Auckland University's Auckland Bioengineering Institute (ABI) building, putting them in close contact with researchers.
That puts it in good company. The Cloud 9 cohort includes JunoFem - whose FemFit measures internal pressure along the wall of the vagina and sends real-time feedback to a mobile app.
Newsmaking companies to come out of ABI include Soul Machines, StretchSense. Formus Labs hopes to join their ranks.