A Study of Common Knee Injuries in Rugby.

As rugby is a full contact sport, it produces a variety of different injuries over the entire body. There is not an exact prescribed way of tackling or taking the ball into contact, so people play in different ways and these alternative interpretations of the rules may contribute to a large number of injuries. Looking at studies done on injuries in rugby, it can be seen they all have similar methods of categorizing the type of injury and its severity. They pinpoint where on the body the injury is and then grade its severity by how many days are lost in training or play.

Common Injuries in Rugby

When looking at rugby injuries there are some areas of the body that are more prone to injuries than others. The most common area of injury is the thigh; most of these injuries are either hamstring strains or ”dead legs”. Hamstring injuries are common due to the ‘stop-start’ nature of the game: a sudden burst of speed can cause a strain in a cold hamstring. Head and neck injuries occur regularly in rugby, usually in forwards, due to scrums collapsing and with close contact in and around rucks. Knee injuries however, along with head and neck injuries, are probably among the most serious injuries in rugby. They may not be the most common, but they can be very severe. On average 10 knee injuries per club per season results in a mean 353 days of absence due to injury. (Dallalana et al. 2007)

The two most commonly occuring and written about injuries in rugby are damage to the ACL (Anterior Cruciate Ligaments) and MCL (Medial Collateral Ligament). A complete rupture of the ACL causes an average of 254 days out and accounted for 2 of 3 retirements due to knee injuries (Dallalana et al. 2007). A MCL tear grade 1, which is the most common and least severe, can cause a minimum of 15 days out. (Dallalana et al.2007)

Studies aim to find out which areas of the game cause the most injuries in order to develop rules to prevent these happening. It has been proven that contact between players accounts for most of the injuries during a game. Tackling, rucks and mauls cause the least amount of injuries, probably due to the fact that players are in control when tackling. The occurrence of injury has been shown to be higher when being tackled compared to making the tackle. (Dallalana et al. 2007) This could be because players are not sure where and when the tackler will be, which limits the ball carrier's ability to avoid injury. Unlike rucks and mauls where changes in the rules can prevent injuries, it would be harder to make the tackle safer without changing the nature of the game. Coaches could be encouraged to teach correct falling techniques as it has been shown that a lot of injuries are due to the way players fall.

Effect of Match Duration on Injury

There is no clear-cut conclusion about what effect time in the match has in relation to occurrence of injuries. One idea is that injuries are fewest in the first quarter of the match. This could be due to players being fully warmed up and fresh at the beginning. Considering fatigue, a theory could be proposed that there would be more injuries in the last quarter due to fatigue. Levels of fitness would also have to be considered, and these would be associated with the stage in the season. For example you would expect players to be fittest at the beginning of the season due to the intense pre-season fitness regimes. The failure of recent suudies to show higher injury rates as the match progresses could be due to the introduction of substitutions of players in 1997, giving coaches an opportunity to substitute fatigued players.

Knee Stability

For a knee to be stable, it relies heavily on ligaments to support it. Knees can only move on one plain and it’s the ligament’s job to prevent any other movements. This is unlike the shoulder and the hip joint, which have their movements limited by the bones. Knee ligament injuries always result in more serious long-term problems than a fracture or a break. This is due to bones being able to regenerate themselves to their previous strength: ligaments are unable to do this. Knee injuries are quite often misdiagnosed as patients report feeling something break: nothing shows up on a radiograph and they are sent home. Usually if they feel a break and there is no bone damage, then it is likely to be a major ligament rupture.

Anterior Cruciate Ligaments (ACL)

The ACL is one of four ligaments that connects the thigh to the shinbone. These ligaments are there to stabilize and keep the knee moving in a controlled manner. The MCL, the ligament down the inside of your knee, works with the LCL, which is on the outside of the knee, to stabilize the side-to-side movements. The other two ligaments are deep inside the knee between the shinbone and the thigh. These ligaments cross over each other at the back. The PCL connects the thigh to the back of the shinbone, the ACL connects to the front of the shinbone. They both control front-to-back stability. The ACL also prevents the rotation of the shinbone and the excessive forward movement of the shin in relation to the thigh.

ACL injuries usually happen as a result of falling awkwardly in a tackle or the knee twisting in an unfamiliar way while trying to change direction quickly. All the injuries are due to the ligament being overstretched in the wrong direction and it either completely snaps (rupture) or it tears. This snap makes a loud ‘pop’ noise from inside the knee. When ligaments rupture they cause the blood vessels to rupture as well which fills the knee with blood, causing excessive swelling. This does not always happen immediately because ACL injuries can give players the impression they can carry on but, as soon as the knee is put under any strain it becomes unstable. A torn ACL is extremely painful immediately after the injury and can result in widespread tenderness around the top of the shin and the bottom of the thigh. If this occurs during a rugby match it is crucial to stretcher off and avoid movement of the knee.

A classic cause of this injury in rugby would be if a tackle was made from behind, down at the ankles. The foot would get stuck in the ground and the weight would then cause excessive forward movement of the shin in relation to the thigh due to the leg being bent. Completely rupturing the ACL would prevent the player taking any further part in the game.

Medial Collateral Ligament (MCL)

As previously stated, the MCL is on the inside of the knee and stabilizes the side-to-side movements. Its function is to prevent the widening and overstretching of the inner portion of the joint; it tries to do this by resisting forces applied to the outside of the knee.

Ligament Injury Grading

Damage to the ligament can cause a strain of different severities. These severities are graded and each grade shows the following side effects:

Grade 1

• There is minor tearing of the fibres of the ligaments.
• Mild tenderness on the inside of the knee over the ligament
• Usually there is no swelling

Grade 2

• There is more extensive ligament damage
• Loses a bit of stability
• Significantly more tenderness especially around the inside of the knee
• Slight swelling occurs.

Grade 3

• This is a complete rupture of the ligaments
• Shows severe instability
• Pain can vary; can sometimes be less painful than grade 2 tears.
  (McRae & Kinninmonth, 1997)

Common Causes of Knee Injury

The most common occurrence of this injury in rugby is during a side on tackle. The weight of the tackler causes the knee to stretch inwards which causes the tear. This is not really preventable especially with tackles being so unpredictable. This is more likely to occur in forwards due to the high contact levels in such short areas. For backs, MCL injuries occur usually when running with the ball: the player’s boot can get planted in the ground and when he tries to change direction, the foot doesn’t move, causing the knee to buckle inwards.

Conclusion

With the nature of rugby being very physical with lots of contact, it is not surprising that there are regular serious injuries. There is scope for more research to be done in the field of rugby injuries to try to prevent so many happening, especially looking into the tackle and ways of trying to make it safer without ruining the game. Also different training programmes should be considered in order to prevent knee injuries occurring at the top level. If a club plays one first-team match per week and one second-team match every other week, they would have an average of two players unavailable to play each week because of knee injuries (Dallalana et al. 2007). This loss of player availability is a serious problem and will only be improved following further detailed study.

References

Dallalana, R.J., Brooks, J.H.M., Kemp, S.P.T., Williams, A.M. (2007). The Epidemiology of Knee Injuries in English Professional Rugby Union. American Journal of Sports Medicine (Online) 35.5, 818-830.

Dandy, D.J., Edwards, D.J., (2003) Essential Orthopaedics and Trauma. 4th Ed. Cambridge: Churchill Livingstone.

Holtzhausen, L.J., Schewellnus, M.P., Jakoet, I., Pretorius, A.L. (2006). The incidence and nature of injuries in South African rugby player in the rugby Super 12 competition. SAMJ (Online) 96.12, 1260-1265.

McRae, R., Kinninmonth, A.W.G. (1997) Orthopaedics and Trauma. Glasgow: Churchill Livingstone.