Tendons are the soft tissue that connects muscles to bone. The quadriceps tendon is responsible for straightening the knee. The four quadriceps muscles converge just above the kneecap (patella) and form the quadriceps tendon which attaches to the patella. Quadriceps tendon tears are relatively uncommon injuries which occur most frequently in middle-aged men. Typically the mechanism of injury involves a sudden muscle contraction on a bent knee. In that moment, the tendon pulls away from the top part of the patella. Patient's often describe "feeling a pop" along with immediate pain and swelling. Walking is nearly impossible as well.
A history of inflammation (tendinitis) in the quadriceps tendon is often reported by patients sustaining quad tendon ruptures. Additionally, there are a number of chronic diseases which can impair blood flow and predispose to tendon injury such as chronic kidney disease, gout, diabetes, and rheumatoid arthritis. Chronic steroid use has been shown to increase the rate of quad tendon injury.
Generally an orthopedic surgeon can diagnose a quad tendon tear based on physical examination alone. Often there is a palpable defect immediately above the patella. The patient will have considerable weakness when trying to extend the knee even against gravity.
X-rays can often be used to confirm the diagnosis. A lateral (side view) x-ray will frequently show the patella sagging closer to the tibia (shin bone) since there is no longer any pull from the quad tendon.
An MRI is not necessary to diagnose a complete tear, but can be helpful in evaluating a partial tear. Additionally, since an MRI shows soft tissues well, the quality of the tendon and exact location of the tear can be evaluated with MRI.
Nonsurgical treatment is generally only appropriate for small partial tears.
Most people with complete tears or high-grade partial tears will require surgery to repair the torn tendon. This is typically done in an outpatient setting so the patient can go home following the surgery. At the time of the procedure, the surgeon attaches the torn quadriceps tendon back to the patella. To do this, the surgeon places strong sutures through the tendon and then threads the sutures through drill holes in the patella. The sutures are then tied at the bottom of the patella. Most surgeons prefer to repair this injury within 2 weeks in order to avoid scarring of the tendon in a shortened position.
Fortunately major complications are uncommon following quad tendon repair. Infections, blood clots, and wound healing problems can rarely occur. More commonly, patients report weakness performing everyday activities including climbing stairs. This complication can largely be avoided with proper physical therapy and a home exercise program. If the tendon does re-tear following surgery, it usually occurs within the first 6 months.
Most surgeons place the leg into a knee immobilizing brace for some period of time (usually 4 to 8 weeks) following surgery. The exact amount of time in the brace may vary depending on age, activity level, quality of the tendon, and surgeon preference. It is critical to follow your surgeons recommendations and postoperative protocol to achieve an optimal result. While most patients are able to resume normal activities including exercise by 6 months, most patients report needing an entire year before reaching all functional goals.