Introduction
Anatomy
Cause
Symptoms
Diagnosis
Non-surgical treatment
Surgical treatment
Rehabilitation
Prevention
Patella tendon rupture is a tear of the patella tendon. The injury tends to occur among younger, recreationally active people, but the exact frequency of occurrence is not clearly known.
Patella is the medical name for what is commonly known as the kneecap, and the patella tendon is the band of tissues that connects the lower end of the quadriceps (a group of four thigh muscles above the knee cap) and kneecap with the tibia (one of the two bones of the lower leg). It serves the important function of extending the knee, i.e. straightening the leg. A rupture of this tendon therefore causes a complete disruption of the knee’s function to extend, making it a debilitating injury.
The rupture occurs as a result of rapid contraction of the quadriceps while the knee is in flexion (bent) as the patient falls.
Certain pre-existing conditions can predispose the kneecap tendon for such an injury. These conditions include inflammation or small tears in the tendon, known as tendinopathy, due to repetitive “micro-traumas” over time; tendon degeneration; and previous injections of steroid into the tendon.
Systemic diseases, such as systemic lupus erythematosus (SLE), may also increase the risk of patella tendon rupture because the tendon is chronically inflamed.
A popping sound and tearing sensation followed by severe disabling pain below the kneecap is felt by the patient during the injury. He will then notice intense swelling of the knee with difficulty in bearing weight.
The injury can usually be diagnosed when the doctor palpates the knee and feels a defect along the tendon, and when he observes that the knee cannot be straightened. An X-ray of the affected area will also show that the kneecap has moved up along the thigh.
Immobilisation of the knee in extension by a brace or plaster has a limited role in treating patella tendon rupture. With non-surgical treatment, the healing between the tendon ends may be less than optimal and the period for immobilisation is lengthened, which in turn slows down the rate of rehabilitation. Full knee extension will not be restored if the patella tendon does not recover to its original length, causing tension after the treatment. Occasionally, non-surgical treatment may be useful in cases of partial patella tendon tears.
Early surgical repair is the usual treatment of choice as the result is more predictable. The torn tendon ends will be opposed by suture in its near anatomical position under general or regional anaesthesia. Additionally, drill holes may be created if necessary through the patella or tibia bone for anchorage of the tendon ends if the rupture occurs close to the bone.
After the surgery, a cast or brace is often used to protect the area during the rehabilitation process. Rehabilitation is an integral part of the treatment as it gives the knee the time to regain its normal functions and strength. The repaired tendon usually takes 6 to 12 weeks to heal but may take up to 6 to 12 months for it to return to its normal strength and function.
Regular training of the lower limbs, especially the quadriceps and hamstring muscles, helps to prevent overuse of the patella tendon. Flexibility training of the knee muscle is equally important in avoiding the occurrence of patella tendonitis/tendinopathy, which is a risk factor for patella tendon rupture. Once symptoms of patella tendinitis, such as pain or tightness below the kneecap, are detected, it is recommended to stop or change the training programme and seek early medical advice to prevent further injury to the muscle and tendon.