OVERVIEW
Patellar tendon is the “cord” that binds the muscles to the bones, a hard band of fibrous connective tissue. The tendons, though they are made to withstand strain, do not, however, have any elasticity, and can be torn off, if a significant force is applied.
The role of the patellar tendon for the knee is to connect the lower pole of the patella to the upper part of the tibia, and to transfer forces from the quadriceps femoris muscle. When it “cooperates” with the quadriceps tendon and the quadriceps femori muscle itself, the knee makes the extension motion. The patella, however, stops working properly when a rupture (partial or total) occurs, namely, when it is torn.
The tears may not extend throughout the whole length, but some “fibers” might have been cut off the tendon, and it can still remain intact. This is the case of a partial rupture. When it is, however cut into two pieces and becomes detached from the patella, then we are talking about a total rupture - it is mainly a sports injury, which basically requires a surgical treatment.

HIGH RISK GROUPS
Rupture to the patellar tendon requires a significant force. A fall with a direct collision upon the anterior surface of the knee is a frequent cause. Jumping and landing on a flexed knee when the foot is on the ground is another one. In addition, a weak tendon is very likely to be torn off, due to its degeneration from chronic conditions (kidney failure, rheumatoid arthritis, diabetes, etc.).
The same happens if an inflammation and swelling coexist, a condition called the “jumper’s knee”, as it is a tendonitis that occurs mainly to those who are involved in jumping and running. The American Academy of Orthopedic Surgeons (AAOS) also “accuse” the use of corticosteroids and anabolic steroids which lead to increased weakness of the muscles and tendons.

WHICH ARE THE SYMPTOMS?
Patients with a patellar tendon rupture can not walk, as the knee is unstable or “loose”, it hurts and it is swollen, and it does not extend fully. The patella can be shifted upwards, as it is pulled by the quadriceps tendon and there is nothing to hold it.
The orthopaedist shall obtain a detailed history of the patient, before examining the knee. Diagnosis is confirmed through a simple X-ray that will show if there is a total rupture, while an MRI shall indicate the extent of the lesion and, at the same time, preclude another injury with the same symptoms.

WHICH IS THE BEST TREATMENT?
The choice of treatment depends on the type and size of the rupture, the age and activity level of the patient. For very small and medium thick ruptures – always in terms with the functional requirements of the patient - conservative treatment, knee immobilization with a functional splint, crutches for 3-6 weeks, and physical therapies that will also strengthen the quadriceps femori muscle and will help the patient regain the range of motion.
However, in traumatic ruptures that are total, surgery is considered to be a one-way road, and, indeed, the sooner it is performed, the better, so that there is no scarring and tendon shrinkage. The goal of the surgeon is to fix the tendon onto the patella, in order for it to have 85-90% of the function of the healthy tendon, post-operatively. Thus, sutures are placed on the tendon and bone sutures are made at the point of its insertion. Bone tunnels are frequently used, in order for the fixation of the tendon to be secure, and for the knee mobilization to take place sooner, post-operatively. If the extent of the damage is much greater than what the initial diagnosis has shown, or if the rupture is extensive, meshes, wires or sutures, which may need to be removed in a subsequent surgery, may be used to hold the patella. If the tendon has considerably “shortened” before surgery, then its reattachment is extremely difficult. In this case, a graft originating from the patient, can be used.
Sutures are removed two weeks after surgery. A functional splint or a long splint boot will protect the surgically treated area, while the partial loading of the foot can be done over a 2-4 week period, and its full loading, in 4-6 weeks. Strengthening exercises are required next. The timeframe for the return to regular activities ranges from 6 to 12 months.