Sports participants who injure their knee were more than twice as likely to have knee replacement (KR) surgery later on than those who had other types of sports-related injuries, the findings of the study have confirmed. Funded by Musculoskeletal Australia and quantifying the likelihood of KR surgery and associated healthcare cost burden 10 to 15 years after sports injury, the research is the first study to evaluate the population burden of KR in people who have previously sustained a sports-related knee injury.

The study, led by Ilana Ackerman, an Associate Professor of Research at the School of Public Health and Preventive Medicine at Monash University, linked two datasets capturing public and private hospital admissions and emergency department presentations in Victoria including sports injury presentations from 2000–2005 (64,038 of which 7205 were knee injuries) and KR admissions from 2000–2015. After adjusting for potential cofounders, the study found that having a sports-related knee injury more than doubled the hazard of subsequent KR, compared to all other sports injuries.

‘We’ve known for many years about the link between knee joint injury and later knee osteoarthritis (OA) but we haven’t really had an understanding of what that looks like in terms of future knee replacement at the population level,’ Ilana says. ‘To see that having a sports-related knee injury more than doubles your likelihood of having a knee replacement within 15 years is quite a startling finding. And that could be the knee joint injury itself leading to OA but also people might already have early knee OA which is exacerbated by the sports injury and then maybe that is speeding up the time to knee replacement.’

Ilana says previous research has shown a significant growth in sports injury rates in Victoria, even after accounting for increasing sports participation in general, and this could translate to a marked growth in future knee OA cases. Almost half of the patient cohort who sustained sports injuries were aged 20–29 years and sporting injuries were shown to be more common among males (78 per cent of all injuries). KR was shown as being more common among the 50–59, 60–69 and over 70 age groups most of the KRs were performed for OA.

‘In our study, the average time to knee replacement surgery was under nine years so it is concerning that people could be having knee replacement surgery at a relatively young age,’ Ilana says. ‘We know that the risk of failure of a knee replacement is much higher in younger patients, potentially requiring revision surgery it’s always best to delay knee replacement as long as possible. It is concerning that a significant proportion of these injuries are occurring in younger people and that’s where we need to be focusing on injury prevention, raising awareness of the potential longer-term impacts of injuries and ensuring that people have access to effective rehabilitation of injuries.’

For physiotherapists, this means it is crucial to undertake effective rehabilitation of patients who experience a knee injury, and to make sure that the patient’s return-to-sport is well planned. ‘From the patient perspective, this is best done in conjunction with their physiotherapist who understands the strength, fitness and biomechanical needs that are required for their specific sport,’ Ilana says.

‘The average time to knee replacement surgery was under nine years so it is concerning that people could be having knee replacement surgery at a relatively young age.’

For the broader sporting population it also has far-reaching implications. Ilana says the findings can be used to improve awareness of sporting injuries and potential outcomes down the line. ‘I think it [the findings] can be used to promote and support participation in injury prevention programs and there are several well-established injury prevention programs available.

‘In the AFL you’ve got the Footy First program, while Netball Australia has the KNEE Program. Soccer also has the FIFA 11+ program. To use the Footy First program as an example, the program was developed using evidence, expert consensus and feedback from the football community. They’re all well-known programs, but we really need to promote the uptake of those so that they become standard care for injury prevention.’

Ornella Clavisi, the general manager of consumer service at Musculoskeletal Australia, says the decision to fund the research centred around its impact on identifying and exploring the link between having a sports injury and going on to subsequently receive knee replacement surgery. Ornella says one of the key messages to come out of the research is the importance of targeted intervention strategies to support injury prevention.

‘It’s important to start early in order to get people thinking about looking after their health and initiatives or what it is they need to do to prevent injuries in the future. That is something that we would be looking into,’ Ornella says. ‘One of the things that we’re looking at, in particular, is the attributable risk of having knee injury and then going on to get knee replacement surgery—and the timeframe from injury to surgery.

‘What is clear from this research is that people need to be aware around having an effective rehabilitation period and not going back to sport too early, to reduce the risk of re-injury, especially after knee reconstruction. And it’s about having the appropriate advice and tools to make informed decisions around that.’

The report highlights that the findings of the study can be used to develop evidence-informed policy recommendations that support health promotion activities, and notes that the ultimate goal is to reduce the frequency of sports injuries that could result in knee OA, Ornella says.

‘I think understanding that there is a link between being injured, developing knee OA or subsequent knee replacement surgery is not something the community is aware of,’ Ornella says. ‘But I also think, particularly for the older age group or people in their mid-40s who might be going out and still playing sport, our bodies aren’t the same. We need to think about taking care of ourselves and the limitations of what we can do, and at least having that conversation and having that evidence in front of us to say “you’re more likely to be injured and you really need to start thinking about what you do when you’re playing sport”.’

The research, ‘Likelihood of knee replacement surgery up to 15 years after sports injury: A population-level data linkage study’, was co-authored with Megan Bohensky, APA Sports Physiotherapist Dr Joanne Kemp and Richard de Steiger. Click here to view the paper.

Associate Professor Ilana Ackerman, APAM, is a musculoskeletal epidemiologist in the School of Public Health and Preventive Medicine at Monash University and an experienced physiotherapist. Ilana’s research program includes clinical and population-based studies that aim to quantify the personal and societal burden of osteoarthritis.  She is chair of the Editorial Board for the Journal of Physiotherapy and sits on the National Advisory Council of the APA.