Raphael Thys
The implants were used for Lin's cranioplasty surgery in July last year. - ST
SINGAPORE (The Straits Times/Asia News Network): When Danny Lin fell in a carpark in November 2020, he injured his head so badly that he could remember only slipping into a coma for about 10 days.
The memory of how the incident happened was completely wiped clean.
"The next moment, when I woke up, the doctors told me that there was some swelling in my brain and that I needed a craniotomy," the 46-year-old headhunter told The Straits Times.
A craniotomy is an operation which involves temporarily removing parts of the skull to ease pressure on the brain due to swelling or bleeding.
Recalling the first day Lin was admitted to hospital, his doctor, Assistant Professor Sein Lwin, a visiting consultant neurosurgeon at National University Hospital, said he found a small blood clot in the right side of the brain.
"He was slowly losing consciousness," noted Prof Sein. "So we repeated the scan, and the clot grew bigger."
This was because the swelling led to pressure building up within the brain, he added.
Bruises were also seen on both sides of the brain due to the impact of the injury, said Prof Sein.
To relieve this pressure, two bone flaps in the skull were removed to help reduce swelling.
Luckily for Lin, the swelling came down in about a week.
"Only 40 per cent of patients fully recover from such injuries and can resume normal activities, while the majority still end up bed-bound. So he's really lucky," said Prof Sein.
The next hurdle, however, was to fix the gaps in Mr Lin's skull, using customised implants - in a surgery known as cranioplasty.
Once a patient's bone has been temporarily removed from his skull, there is a small window - of around six to eight weeks - for surgeons to reinstate and return the bone to its original place.
Beyond that timeframe, the bone tissue will gradually degrade due to the lack of blood flow and nutrients, such that it becomes akin to a foreign body once it is returned to the patient. This can cause infection and other complications, said Prof Sein.
However, for cases like Lin's, a timeframe of three to six months would be needed to ensure that the swelling comes down entirely, before the surgeons can embark on the cranioplasty surgery, said Prof Sein.
He turned to local medtech company Osteopore International to customise two implants - which were about one-third the size of Lin's skull - for him.
Osteopore's co-founder, Professor Teoh Swee Hin, who was also the president's chair of the Nanyang Technological University's School of Chemical and Biomedical Engineering, said its implants are biodegradable and serve as a scaffold for new bone to grow.
These implants are made primarily from a material known as polycaprolactone (PCL), a type of polymer.
"As PCL degrades slowly, over a course of 18 to 24 months, the body's cells are given enough time to do their work, which is to create new bone," said Prof Teoh.
Another ingredient used in the scaffold is tricalcium phosphate - a type of mineral which is key in ensuring the health and density of the new bone.
Both materials help to create a conducive micro-architecture for natural tissue regeneration.
In the past, the use of titanium implants had long been the norm. However, in the long term, these are prone to rejection by the body and can cause infection, he added.
"Titanium also does not conform well to the contours of the skull, and the material can easily expand," said Prof Teoh.
The implants, which cost between $10,000 and $20,000 in total, were used for Lin's cranioplasty surgery in July last year.
Some of Lin's own bone marrow - which are a rich source of stem cells - were also tapped to help accelerate bone growth. Stem cells are like the body's "master cells" and can be programmed to create bones, skin grafts and a range of other body parts.
The operation turned out to be a success and Lin was discharged from hospital within two weeks, said Prof Sein.
A review of his case in January - just six months after his surgery - showed new bone growth.
"We would still need to monitor his case for another year or so to ensure good bone strength and density," he added.
Prof Sein previously operated on two other patients with Osteopore's implants, but this is the first time he has done a cranioplasty with an implant of this size.
"Lin has been recovering well, so I'm optimistic," he said.
Only a small scar can be seen on the side of Lin's head, but otherwise, much of his life has resumed to normality.
Lin said: "I've already been able to go back to work since then and everything went by smoothly. For that, I'm very thankful."