Luckless Carlton forward Charlie Curnow is facing a tough road to recovery following his latest setback after fracturing his patella in a light session with his brother, Ed.

The 23-year-old missed the entirety of the 2020 season with a previous knee injury that added to an already-riddled career.

Curnow underwent surgery in March and had his season drawn to a premature close by April, with his last game in the navy blue coming in Round 15 last year.

The Carlton spearhead will continue to battle against the setbacks in an effort to make a miraculous return to the AFL.

Sports medicine expert Dr Peter Larkins told The Herald Sun that stress injuries to the patella are uncommon in the football world, with Curnow's latest injury a warning sign that his body isn't coping well with the physical strains of AFL training.

Dr Larkins said the injury could be “career-altering” for the luckless forward.

“Once he broke the patella (last year), it changes the shape of the patella and it potentially changes the cushioning surface of the patella quite a bit,” Dr Larkins said.

“So what happened, when he got back to training after they repaired the broken patella, he was getting stress in the bone.

“That was the reason he had to back off at a fairly low level and I didn’t think that augured well when he was trying to get back in the early days of this season.

“Now that he has had a recurrence of that patella stress again, it really means that the bone is not coping with the loads of AFL training.

“There is a lot of pressure that goes through the front of the knee and therefore through the kneecap in any sporting situation.

“When you fracture the patella you will damage the cartilage, so the likelihood of developing degeneration or arthritis goes up enormously after you break a patella bone; the ability for it to absorb shock and absorb jarring means it doesn’t like stress.

“Therefore, the way that he would go about training for the rest of his career I think could be altered … it is certainly career-altering for him.

“The bone itself isn’t coping naturally, so they are trying to make it stronger.

“We don’t talk about this sort of injury very often …. because normally the patella doesn’t really get stress fractures.

“The last time we had someone getting stress in a patella was Tom Scully when he played at Melbourne … but he didn’t have a fractured patella, which Curnow had.

“Curnow’s patella will never look the same again on any scan or any X-ray he has for the rest of his life.”

Dr Larkins added that Curnow may need to alter the way he trains for the remainder of his career.

“I am concerned about his ability to absorb AFL training loads,” Dr Larkins said.

“There is a concern that he will never get back to the level of fitness required to be an elite AFL player, which he is capable of being based on talent, there is no question about that.

“But I am still looking at the upside of getting this surgery done and getting the bone strengthened up.”

Curnow has played 58 games and has kicked 77 goals since being drafted to the Blues in 2015.