Explainer: What is a stress fracture and why does it happen?

Sportstar caught up with former Indian team physio John Gloster to know about stress reaction and stress fracture.

Bumrah was ruled out of the South Africa T20Is because of a back injury. | Photo Credit: AP

As the Indian cricket fans await an update on Jasprit Bumrah’s injury ahead of the T20 World Cup, the BCCI is still optimistic about the pace spearhead’s participation in the tournament.

While Bumrah’s latest reports suggest the injury is not as grave as it was thought earlier, Sportstar caught up with former Indian team physio John Gloster to know about stress reaction and stress fracture.

What is a stress fracture?

It is very unfortunate for any athlete, particularly Jasprit, to have this injury at this particular time because these types of injuries are quite debilitating. My best wishes go out to him for his recovery.

These injuries aren’t uncommon, we tend to see them more in young fast bowlers. When I’m talking about stress fractures, I’m not talking about a particular stress fracture related to an individual because they are all very different.

I’m not familiar with Jasprit’s history or case, so we will talk generally. But the worst thing about a stress fracture is that it does take a player out of the game. And it can be cricket, tennis, javelin throw – any sport that involves repeated hyper-extension stresses. It takes them out of the game for a significant period of time.

We need to differentiate between a stress reaction and a stress fracture. They are both stress injuries to bone, and a stress reaction is a precursor to a stress fracture. If you repeatedly stress any bone without any protection for that bone, then it causes inflammation in the bone – we call it bone edema or a ‘bone bruise’.

It’s like any bruise - if you keep poking at a bruise, it stays bruised. Same with bone – if we keep repeatedly loading that piece of bone with the same stresses, that bone edema area will eventually turn into a stress fracture.

Remodeling or reforming of new bone is a normal reaction to loading of any bone. However, if the process of the remodeling is outstripped by the resorption (removal) of that bone then that causes a stress fracture.

In other words, when bony load exceeds the bone capacity and there’s an imbalance between the bone resorption (by the bone’s osteoclast cells) and the bone formation process (by the osteoblast cells) within the bone then that’s what leads to the the breakdown of that segment of bone (stress fracture).

Also understand that this piece of bone (the pars) which we are talking about in the lower back is very small. During the delivery action of bowling the entire force of that that is going through a piece of bone which has a x-sectional area of only 0.75 sq.cm on each side (for a total x-sectional area of 1.5cm² for each neural arch).

So it’s a very tiny little piece of bone. And that’s usually where these lumbar stress fractures occur. So what happens is if we can’t protect that piece of bone and repeatedly keep loading that, it starts to get bruised, which is the stress reaction. It eventually turns into a stress fracture and can crack right through; that’s sort of the end stage.

How much time can it take to recover?

It is very individual and depends on a number of factors. Those factors can also be the ones that contributed to the injury in the first place. Some of those factors could be things like nutrition, hormone levels, Vitamin D-III and calcium levels as well as the more obvious ones like the bowling action (more so if it is in the younger cohort with first time incidence), training, poor gym programs or through direct bowling ‘overload’ or spikes in load.

In order to allow this to recover, we need to firstly eliminate the stressor - in this case it’s the act of bowling or any other activity that loads or stresses the pars bone in the low back (example, weights in the gym). Along with this we need to ensure that all the internal parameters like the blood markers are good, nutrition is addressed, etc and then the process of healing starts.

It could be anywhere between a couple of weeks and six months. If it is a simple bone stress reaction, they can resolve anywhere between eight to 10 weeks.

But if it has been diagnosed as a stress fracture, it can take up to six months.

If a player has a really good physiological and medical history and has undertaken a protective rehab programme, then that can be accelerated to three months or so. That also depends on the extent of the fracture and at what stage it is at. But one needs to understand that all these bones that are subject to stress rely on and require shock absorbers around them. Another major contributor or precursor to stress injury in bones is fatigue, particularly muscle fatigue in those muscles that help support the spine.

So, if muscles fatigue or they are not adequately prepared for the efforts you are going to put them under, and they start getting tired, they stop supporting the bony structures they are designed to support. For a fast bowler, the calf muscles are particularly important, believe it or not. Calves are the primary shock absorbers for the forces that come from the foot up through the leg into the spine. So, if your calf is fatiguing, and your hamstring/Quadriceps complex also fatigues , your glute muscles and core stabilisers fatigue, then you are putting that tiny little bone under undue stress.

If you repeatedly do that, you will end up with a bone stress injury. Time frames for recovery can be anywhere between two to 10 weeks for stress reactions, while it may take anywhere up to six months for stress fractures.

What is the recovery process?

We go back and look at all the parameters, we look at the load and work out why it happened in the first place. For a bowler like Bumrah, people say, “Oh, it happens because of his action…” but I don’t agree with that because he has been bowling with that action for probably 15 years or more now. So I don’t think it’s because of his action.

So most fractures occur because of changing the load (training, match bowling loads and gym) and either repeatedly overloading without the adequate rest periods, or after a period of rest and then a spike in load, that’s probably one of the most dangerous ones.

We have the ability to monitor load very closely these days with the GPS and other tracking devices. But one of the things that I look at is monitoring the fatigue component I mentioned, and this can be determined by a number of things – even poor sleep patterns can cascade into physiological fatigue.

‘Fatigue’ can arise from several sources: poor nutrition, poor muscle preparation (training), over-training, even environmental factors that lead to dehydration etc. One must also consider ‘neural fatigue’, which can lead to poor muscular protection of the spine. When the neural (nerve) tissue is stressed, that can cause muscle to behave differently. And then, if those key muscle groups mentioned before start to shut down because they are fatigued, they stop protecting this primary structure.

So, we revisit load, action, blood & physiological markers to determine why this possibly happened in the first place. The easier part of this injury is the actual physical rehab. There are some really good set protocols that exist for rehabilitating spinal stress injuries in this cohort. One such protocol that is important is to keep this player in a period of what we call ‘active rest’ as much as possible; ie, they rest from the aggravating activities (in this case the hyperextension, rotation, lateral flexion and compression spinal movements), we remove those so that area is resting and the bone bruise and the fracture is healing. But at the same time, keep the player doing other activities to keep them cardiovascularly fit, activate key supporting muscle groups and modify their nutritional inputs if required along with their bowling action if that was a source of their issue in the first place.

The aim is to get all the muscles fired up and help to protect that bone area from further stress.

So, the rehab programmes are really good these days, and I think we have accelerated the return of most stress injuries based on the information and data we have recorded from previous stress injury cases. It’s a very structured program now and well supervised.

Someone with a previous history, who has been in a well managed environment, someone like him, would be in the shorter three to four months rather than a six month bracket.

Can it be career threatening?

For some individuals, yes. But more so in the younger age bracket. So, if you are a fast bowler who has, what we call a ‘bilateral stress fractures’ of the pars, this can cause a condition called spondylolisthesis (where you have stress fractures on either side of the vertebrae and one vertebrae slips forward or backward on another one). If this happens at a young age, for example, between the 14 to 17-18 age bracket, the chances of that young bowler maintaining their career as a fast bowler is limited.

Stress fractures that are one-sided and don’t have a spondylolisthesis component do significantly better. Anybody who has stress fracture now in the current environment and current management, pretty much all of them return to high-level cricket. For somebody like Bumrah, this is certainly not career threatening.