Welcome to the very first edition of The Learn.Physio Journal Club!

Thanks for tuning in and reading! I'm going to kick off my first review summarising 2 recent articles that are very important to me as a clinician - injury prevention programs and ACL reconstruction rehab.

Firstly, I cover a recent systematic review and meta-analysis looking at injury prevention in female soccer/football. Then I look at a paper showing some fascinating insight to strength and hop performance measures in the ACLR patient 5 years after their reconstruction. 

So without further ado, let's get into it!
Injury prevention programs in sport have been researched extensively for many years in many different sporting codes, across both males and females; however examining the specific effects of injury prevention programs in female soccer athletes has not been clearly established. 

With the rise of women's sporting codes across Australia and the rest of the world, in particular soccer, it would be prudent for key stakeholders of each soccer organisation to understand what are the main injuries sustained in soccer, and what are the key components of injury prevention programs, to ensure that our best soccer talent can stay on the paddock. 

A group of world leading researchers here in Melbourne recently conducted a systematic review and meta-analysis to try and answer these questions. The authors identified 12 studies that met the inclusion criteria of their systematic review and meta-analysis. These 12 studies had nearly 12,000 athletes (with a mean age range from 11 years old through to 23 years old) to analyse which is tremendous strength to this review. 

The most common intervention applied to the female soccer players was a ''neuromuscular training program'' which is a broad term that encompasses multiple training components such as strength, agility, balance, plyometric exercises, running drills and mobility exercises. There was only 1 included trial in this review that had 1 training component only (Nordic Hamstring strengthening). 

When the authors crunched the numbers; compared to a control group within each individual study (who all performed their ''usual'' warm-up before training and games), they found the following: 
  • 27% reduction in overall injury incidence in female soccer athletes when multiple training components are performed (significant difference) 
  • 45% ACL injury risk reduction in female soccer athletes when multiple training components are performed (significant difference) 
  • 17% knee injury risk reduction in female soccer athletes when multiple training components are performed (non-significant difference) 
  • 22% ankle injury risk reduction in female soccer athletes when multiple training components are performed (non-significant difference)
  • 29% hip/groin injury risk reduction in female soccer athletes when multiple training components are performed (non-significant difference)
  • 40% hamstring injury risk reduction in female soccer athletes when multiple training components are performed (non-significant difference)

Despite the limitations to this systematic review and meta-analysis (low level of evidence and inconsistent injury definitions and reporting of injury), two key findings did shine through. 

First and foremost, multiple component injury prevention programs have the power to reduce all types of lower limb injuries (ACL, knee, hip, groin, hamstring, ankle) in female soccer athletes by 27%.

Secondly, to the injury that can have the most significant impact on a player and a team in the short term, and to the individual in the long term - the ACL injury - they can be reduced by nearly 50% with the implementation of a multiple training component injury prevention program. 

These findings are an important step forward for all key stakeholders involved in junior and senior female soccer, not just here in Australia, but all around the world. When you look at these findings presented by Crossley et al (2020) and combine it with previous findings from Sugimoto et al (2014) which showed that neuromuscular training programs performed for at least 30mins per week reduce the risk of ACL injuries in females by 68%.

From a practical perspective what this means is that whatever has been previously used as a 10-15mins warm-up (or ''usual'' routine) can be simply replaced by a new 10-15min warm up that includes strengthening exercises, balance drills, plyometrics and agility drills. If this program is conducted before each training session per week (usually 2x per week) and every game (usually 1x per week) it goes to show how little time each week young female athletes need to commit to, to have a significant impact on their ability to play and perform in the sports that they love, but also reduce the risk of sustaining a significant ACL injury that can impact them in the short term, but can and will most certainly impact them in the long term. 
Reference Links 
Functional testing of the ACLR athlete is strongly advocated for when determining the athlete's readiness to return to sport. A common discharge milestone for any given strength test or functional test is >90% limb symmetry index (LSI); as it has been shown to reduce knee re-injury risk, have better knee symptoms and QOL, and reduced risk of knee osteoarthritis.

However, using LSI as an outcome measure has been challenged recently as it has been found that it may in fact over-estimate the function of the athlete as the uninjured limb can be a poor and unreliable reference point to compare to. 

LSI = injured limb / uninjured limb x 100
What is not often found in the literature are follow up studies on strength and performance after 2 years post-op, so Patterson et al (2020) set about looking at functional test results 1-5 years following ACLR. 

They also wanted to know how the performance in these tests compared against healthy controls who have never had an ACLR.

So Brooke and her team of researchers gathered data on 4 lower limb performance tests that were performed at baseline (1 year post-op) and then once again at follow-up (5 years follow-up) post ACLR. These tests were: 

  • Single leg hop test
  • Triple crossover hop test
  • Side hop test
  • 1 - leg rise test

59 patients were able to be evaluated on complete data sets at baseline (1 year post-op) and at 5 year follow-up. The average age of the participants at baseline testing was 29 years of age with a mean BMI 24.9 (increased 25.6 at 5 year follow up). 

Prior to ACLR 88% of the group participated in the level 1 or 2 sports. At 1 year post-op 34% participated in level 1 or 2 sports and 24% participated in level 3 sports and 42% were now classified as being sedentary. At 5 year follow-up, 41% were participating in level 1-2 sports, 47% level 3 sports and only 12% sedentary. 

Note: Reference data from healthy controls were of a younger age group 5 years (hop tests) and 3 years (single leg rise)

Functional performance in ACLR limb did not change between 1 and 5 year follow-up; except for single leg hop test which actually increased significantly. 

In contrast the uninjured limb decreased performance between 1 and 5 year follow up; most notable for triple crossover, side hop test and single leg rise test. This lead to the LSI scores for the single leg hop test, side hop test and one leg rise test to increase. 

At 1 year post op ACLR, only the single leg hop test for both ACLR and uninjured limbs were significantly lower than the healthy control (even when adjusting and accounting for age and BMI). 

At 5 year post-op ACLR the side hop test LSI was the only test to be significantly lower than the healthy controls. 

Function changes between ACLR limbs and uninjured limbs during the first 5 years - however the biggest changes occur in the previously uninjured limb and not the ACLR limb. As a result this decline in performance of the uninjured limb gives the athlete a better LSI score, that will over-estimate how well the athlete is in fact doing. 

These fascinating findings reinforce the need to tread very carefully when using LSI as an outcome measure to determine readiness to return to sport, or give a previous ACLR patient an indication of their lower limb performance that may be influencing their QOL or risk of knee OA progression. 

It seems that a more sensible outcome measure would be to use post-injury data (within weeks of the acute ACL injury) of the athletes uninjured limb as a reference point to be used at a later date as per Wellsandt et al; or use normative data from healthy controls to compare against. 

Hop testing provides a highly accessible and low cost alternative to isokinetic and biomechanical testing, but they can not and should not be used in isolation to assume that someone has adequate quadriceps and hamstring strength (which <90% LSI is known to increase knee reinjury risk). ACLR patients have a great capacity to compensate throughout a functional task like a hop test, most commonly through the hip, despite being able to achieve the goal and have equal hop distance (Kotsifaki et al 2020).

In summary, clinicians need to be very cautious of using hop tests in clinical practice in isolation as the previously uninjured limb at the time of testing can be a very poor and unreliable reference point - ultimately over-estimating the athletes' readiness to return to sport. In a perfect world, we would all measure the single leg hop performance of the uninjured limb soon after the ACL injury when the patient is at the fittest and strongest - this will provide a better benchmark for clinicians to work towards in order to get the athlete back to. 

In the event that we cannot get pre-op injury data, using normative data of healthy controls would be a sensible option. What this study also highlights is the need for ACLR patients to make a longer commitment to their knee (way beyond 12 months and to be honest, a life-long commitment) to ensure that function, quality of life remain to be high and the impact of knee osteoarthritis changes that occur over time are reduced. 


Thanks for reading and staying up to date. I look forward to sharing more in the future.

If you enjoyed the reviews, I'd be grateful if you told your colleagues about the Learn.Physio Journal Club.

Stay Tuned for our Next Issue

Copyright © *|CURRENT_YEAR|* *|LIST:COMPANY|*, All rights reserved.

Our mailing address is:

Want to change how you receive these emails?
You can update your preferences or unsubscribe from this list.