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Patellar tendon rupture

A patellar tendon rupture is a complete breaking of the patellar tendon under the kneecap.

Causes of patellar tendon rupture include:

• direct blow or cut to the tendon
• stress combined with pre-existing weakness in the tendon (possibly from one of - steroid injection into the area, gout, repetitive exercise strain, arthritis, diabetes, growths)

Symptoms include difficulty straightening the knee against gravity compared to the other side, and a tender, painful gap below the kneecap. X-ray may show patella alta (high riding kneecap).

The patient is usually under 40 years of age. Above that age, similar injury forces usually results instead in rupture of the quadriceps tendon above the kneecap.

It is vital that surgery be done early to pull the tendon back to its normal place (with circlage wires) or complications are very likely, and include a high riding kneecap with pain in the front of the knee. Joint cartilage damage may follow. The kneecap may also get stuck down with scar tissue (arthrofibrosis).

Over-enthusiastic repair with insufficient rehab may lead to a low-riding kneecap, patella baja (which is drastic).