Knee Injuries
The knee joint is the largest and one of the most complex joints in the human body. It is also a joint that is used for almost every activity from standing up to walking to changing direction while running with the ball on the field. The knee joint is a marvel of functional anatomy, situated at the intersection of the femur, tibia, and patella. Its primary function is to provide stability and mobility, enabling us to perform a range of activities.
SUMMARY OF FUNCTIONAL ANATOMY
The knee joint is a hinge joint, allowing flexion and extension, much like a door swinging open and closed. The major bones involved are the femur, which forms the upper portion, and the tibia, which comprises the lower part of the joint. The patella, or kneecap, lies in front of the joint and aids in the distribution of forces and protecting the knee during movements.
Additionally, the knee joint relies on an intricate system of ligaments, tendons, and muscles. Four primary ligaments provide essential stability: the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medial collateral ligament (MCL), and lateral collateral ligament (LCL). These ligaments provide stability by preventing excessive forward, backward, and lateral movement of the knee.
The surrounding muscles, including the quadriceps, hamstrings, and calf muscles, play a crucial role in generating movement and stability. The quadriceps muscles extend the knee, while the hamstrings flex it. The articular cartilage, synovial fluid and menisci within the joint facilitate smooth motion and reduce friction.
Understanding the knee’s functional anatomy is essential for addressing injuries within physiotherapy. Repetitive activities can result in what is known as “overuse injuries” such as tendinopathies, arthritis & bursitis. A combination of speed and force can result in an acute traumatic injury such as ligament sprains, muscle tears and meniscus lesions. Any disruption or injury to any one of the structures in the knee can result in pain, instability, reduced mobility and poor or altered biomechanics. Let’s have a look at some common injuries we usually encounter.
Jumper’s Knee:
Jumper’s knee, also known as patellar tendinopathy or patellar tendinitis, is a condition characterized by pain and inflammation in the patellar tendon. It’s often provoked by sports and activities that involve repetitive jumping or running, such as netball and athletics. Overuse and strain on the tendon can lead to this condition, causing pain just below the kneecap. Jumper’s knee is typically load-related, meaning that it is directly related to the increase in demand on the quadriceps muscles.
When you prepare to jump (assume the bent-knees position), the patella tendon stores energy which is then transmitted when the quadriceps muscles quickly contract during the spring action of jumping. Upon landing from such a powerful jump, the muscles around the knee including the quadriceps and of course, the patella tendon, eccentrically control the forces and weight of the body. The patella tendon evidently takes on quite a crucial role in absorbing and transmitting forces. Now, think of how repetitive this entire process is during certain sports. It certainly places a high demand on the patella tendon subsequently resulting in what we call, Jumper’s knee.
Runner’s Knee:
Runner’s knee, also known as patellofemoral pain syndrome (PFPS), is a common condition among athletes, particularly runners. It’s characterized by pain felt around or behind the patella due to irritation of the cartilage on the undersurface of the patella. When the knee moves inward and outward excessively during running, it can cause poor tracking and poor alignment of the patella. Running with poor patella tracking and poor alignment can then cause poor distribution of load on the joint resulting in degradation of the cartilage under the patella.
Contributing factors to runner’s knee can be both intrinsic and extrinsic involving the hip and knee joint.
Contributing factors:
- Muscle imbalances
- Altered biomechanics when running eg. flat feet
- Incorrect form while training
- Incorrect training shoes
- Changing training surfaces
ACL tear:
The anterior cruciate ligament (ACL) tears are often associated with meniscus tears resulting from the limb twisting with the foot anchored to the ground or while rotation occurs within the knee joint while it is bent. Such an incident commonly occurs on the rugby or soccer field, or in similar sports and activities. The ACL primarily provides stability within the knee to prevent excessive forward translation of the tibia relative to the femur. The ACL also helps to control and resist rotational movements within the knee during movement. While the ACL exerts control of all these multi-directional forces within the knee, it becomes susceptible to sustaining a tear whether partial or complete, when the anterior and rotational forces placed on the ACL are maximal.
Common symptoms:
- An audible “pop” or “crack” at the time of injury
- Feeling a loss of stability in the knee
- Swelling, widespread tenderness
- Pain in the knee
- Movement restriction – inability to fully extend the knee
- Tenderness at the medial side of the joint
Meniscus Lesion
The menisci are shock absorbers that distribute the weight and force in the knee. Meniscal lesions, as we know, can happen in the same instance as a result of the same forces applied on the knee joint when the ACL (or any other ligament) is torn. This is then considered an acute or traumatic lesion. The menisci can also develop degenerative meniscal tears as a result of life-long, repetitive forces that have been placed on the knee joint.
Common Symptoms:
- Joint line tenderness
- Popping/clicking sound and intermittent residual pain.
- Pain and stiffness after maintaining a flexed knee position for some time
- Pain and stiffness in weight-bearing flexed knee positions eg. squat
- “Catching”, or the knee joint getting “stuck”
These are just a few of the injuries that are typically seen in knee joints. Of course, much like any other injury it is always recommended to seek assessment, diagnosis and treatment. Some injuries, such as severe ACL and meniscus tears may require surgery, whereas some can be remedied conservatively with physiotherapy rehabilitation. Preventative strengthening can help you to avoid sustaining overuse injuries and assist you in recovering from traumatic injuries with a little more ease.
