Are you familiar with the most common knee injuries?

Knee injuries can be divided into two categories: acute injuries, and overuse injuries. This page provides an overview of the most common injuries from both of these categories.

Acute injuries occur most often in sports where there is a high risk of falling, or where there are a lot of contact. These injuries occur instantly and without warning.

Overuse injuries develop over time and are not the result of one inciting event. The cause is usually from overloading over a period. The good news is that these can be prevented by (amongst other things) adjusting the training load in relation to one's abilities for performance and tolerance.

Even though acute injuries often occur unexpectedly, it is still possible to aid in their prevention. 

Acute knee injuries

Anterior cruciate ligament injuries

Cruciate ligaments are like seatbelts that prohibit unwanted movements as well as contributing to stability in the knee joint. ACL injuries are especially common in sports with sudden changes in direction such as football, basketball, handball and downhill skiing. This type of injury results in an extended rehabilitation period away from competitive sport (often up to 12 months). Therefore, it is important to try to prevent them.

Surgery following an ACL injury is not a given. On the contrary, about 50% of ACL injuries in Norway today are treated conservatively (rehabilitation without surgery). Many in this situation have good results. A football player or downhill skier at the elite level with an ACL injury often receives surgical treatment while a cross-country skier, cyclist, or runner can more often do without.

Rehabilitation with a physiotherapist is hard whether or not surgery is involved. Close follow-up for at least 6 to 12 months is necessary to maintain all aspects of the rehabilitation process. The decision to return to sport should be made by the athlete in conjunction with their doctor, physiotherapist, and trainer.

Posterior cruciate ligament

Injuries to the posterior cruciate ligament (PCL) are far less common than ACL injuries. Sports-related injuries account for 50% of PCL injuries while the remainder is the result of traffic accidents. Posterior cruciate ligament injuries without any additional injuries involving other structures in the knee are usually treated by following an intensive rehabilitation training program. Surgery is not usually involved. The results are often good. Surgery may be necessary if there are additional injuries involving other structures in the knee. Following a PCL injury, it is estimated to take a minimum 6 months of rehabilitation before the athlete can return to sport.

Meniscal injuries

There are two menisci in each knee joint: the medial meniscus and the lateral meniscus. They are located on either side of the knee and they function as shock absorbers as well as contributing to the stability of the knee joint. It is more common to injure the medial meniscus (the one on the inside of the knee).

Acute meniscal injuries are most common in younger athletes. Changes due to ageing (degenerative changes) of the meniscus happen over time, usually amongst middle-aged and older adults. It is important to distinguish between these two types of injuries as they are treated differently. Surgery is often necessary with acute injuries, either to remove part of the meniscus or to repair it. Degenerative injuries should first and foremost be treated with physical exercise, and most people will recover just fine without surgery.

Having close follow-up during the rehabilitation process is important. The meniscus will gradually be able to handle more weight-bearing activities. The training program should reflect this by increasing demands on the athlete - as long as their knee can handle it.

Collateral ligament injuries

There are two strong ligaments (the medial and the lateral collateral ligaments) located on either side of the knee. These connect the shinbone to the thighbone and prevent it from being pushed out to the sides. It is more common to injure the medial collateral ligament (on the inside of the knee). Injuries to the lateral collateral ligament on the outside of the knee are far less common but tend to be more complicated due to the potential for additional injuries to ligaments and tendons in that area. Following rehabilitation, the athlete can typically return to sport without any further problems.

Dislocated kneecap

A dislocated kneecap is a common injury for active teenagers and young adults. It is more frequent in girls than boys. The injury can result from a direct hit, but it is more often associated with a twisting motion and no contact. A dislocated kneecap will almost always involve the kneecap going outwards. This process can lead to damage along the middle edge of the kneecap. Most first time injuries of this type are treated without surgery. The focus of rehabilitation is to minimise the risk of a re-injury.

Overuse knee injuries

Jumper's knee

Jumper's knee is an overuse injury that often affects athletes in sports that involve a lot of jumping. It is widespread in sports such as volleyball and basketball and twice as common in male than female athletes. Pain is exacerbated by heavy loads placed on the tendons, e.g., by jumping or quick changes in direction.

Treatment for jumper's knee usually takes a long time. Many athletes want to know if they can continue to participate in sports as normal, but the answer to this varies.  With rehabilitation for jumper's knee, one should map out, adjust, and customise the total training program.

Anterior knee pain / Patellofemoral pain syndrome (PFPS)

Knee pain is extremely common amongst adolescents who play sports, and patellofemoral pain syndrome (PFPS) is the most common condition. PFPS accounts for 50% of non-specific knee pain. PFPS is most common in the 16-25 age group and especially in cycling and running sports.

Several potential factors might lead to an athlete developing PFPS. Gender is one of these factors; female athletes have 1.5 - 3 times higher incidence of PFPS than their male counterparts. The treatment of PFPS has a holistic approach that takes into consideration all the potential factors that might have caused the condition. Load management is still one of the most important aspects of effective treatment of PFPS, and the athlete's total training program should be summarised and evaluated. The return to sport should be gradual and well-structured with an important role played by the coaching staff.

Osgood-Schlatter and Sinding-Larsen-Johansson diseases

Both are common conditions in growing adolescents, and they employ the same treatments. Boys between the ages of 12 and 15, i.e. in the middle of their growth-spurt, are the most at-risk but the condition also affects girls.

The most important aspect when treating these conditions is to adjust the daily level of activity. This might involve refraining from certain activities which cause a lot of pain for a while so that the symptoms can subside.

It is important to emphasise that one can still be active with either of these conditions, but it may be wise to take the total amount of exercise into account. Then it will be possible to determine which activities to continue and which to avoid for a while. Guidance from a physiotherapist with expertise in the area is recommended so that they can assist the athlete to maintain participation in the sport in which they are active. This should also be done in collaboration with the coach(es). The long-term outcome is positive.