The patella tendon is a strong band of tissue that connects the kneecap (patella) to the shinbone (tibia). Collagen fibres arranged in a parallel pattern form the tendon, granting it high levels of strength and flexibility. Located just below the kneecap, the patella tendon is part of the makeup of the extensor mechanism of the knee, which is responsible for the extension of the knee joint, allowing us to straighten our legs and stand up.
A patella tendon rupture, also known as a patella tendon tear, occurs when there is a tear (either partial or complete) of the patella tendon. It can make it difficult or even impossible to extend the knee joint or straighten the leg. Thus, impairing a person’s ability to walk, run, or perform other activities which require the use of the knee joint.
There are 3 types of patella tendon rupture, these are:
Partial tear: tendon is damaged but not completely separated.
Complete tear: tendon is fully ruptured and no longer connected to the kneecap (patella) or shinbone (tibia).
Avulsion tear: tendon torn away from the bone, pulling a fragment of bone along.
A patella tendon rupture is characterised into 3 grades depending on severity, these are:
Grade 1: tendon is partially torn, but the fibres are still intact enabling the knee to still bear weight, and perform some movements.
Grade 2: tendon is significantly damaged, with partial tearing of the fibres leading to difficulty in bearing weight and experiencing pain, swelling, and weakness.
Grade 3: tendon is completely torn or detached from the patella or tibia, resulting in the inability to straighten the leg or bear weight on the affected leg.
What causes a patella tendon rupture?
A patella tendon rupture is typically the result of a sudden and forceful movement of the knee, or by a direct blow or impact to the front of the knee.
The following are some of the most prevalent causes of a patellar tendon rupture:
Direct blow to the knee, such as a fall or a sports-related collision
Repetitive stress on the tendon stems from intense knee-related activities
Degenerative changes lead to weakening of the tendon, making it more prone to injuries
Pre-existing medical conditions can increase the likelihood of a rupture
Existing knee injuries can cause a complete rupture of the patella tendon
What are the symptoms of a patella tendon rupture?
Symptoms of a patella tendon rupture include:
A loud “pop” or “snap” when an injury occurs
Severely impaired walking and standing ability
Swelling and bruising around the affected knee
Inability to bear weight on the affected leg
Sudden burst of severe pain at the time of injury
If you notice any of the symptoms, make an appointment with an orthopaedic specialist to get an accurate diagnosis and treatment.
Dr Puah KL is our Senior Consultant Orthopaedic Surgeon at Artisan Sports & Orthopaedic Surgery. He used to serve the sports service of Singapore General Hospital - the highest volume trauma centre for orthopaedics in Singapore.
Yes. When the tear first occurs, the individual will experience a sudden and intense jolt in the front of the knee (depending on the severity of the tear), resulting in an inability to move or bear weight on the affected leg.
In the subsequent hours and days, swelling will develop around the knee, and it will be tender to the touch.
Who is at risk of a patella tendon rupture in Singapore?
Patella tendon rupture can occur in anyone, but the following factors increase your risk:
Athletes: patella tendon ruptures are common among athletes of football, volleyball, and basketball.
Gender: men are generally more prone to patella tendon rupture than women.
Age: people aged 40-60 tend to suffer from this injury as a result of an overall weakened tendon consistently under high levels of stress.
Steroid use: continuous steroid usage weakens the tendons and thus, increases the likelihood of a rupture.
Chronic knee problems: individuals with a history of knee issues may be at higher risk of a rupture.
How is patella tendon rupture diagnosed?
Diagnosis of patellar tendon rupture occurs in the following ways:
Physical examination and medical history: inform your orthopaedist of the potential activities that may have led to an injury such as trauma, exercise, or sports. Physically the area of injury will be examined and several motion tests will be conducted to review the injury.