The Meniscus (also known as cartilage) is a fibrocartilage in the knee that has a very unique shape, design and purpose. The purpose of the meniscus is act as a shock absorber and space filler between the bones of the knee. The menisci are of a “C” shape which corresponds and is contoured to the surface of the femur. They also have a wedge-like shape to them that helps with stability. This would be similar to the wedges used as door stops or a slice of an apple.
As stated, the meniscus is the primary shock absorber in the knee. It helps to dissipate the forces in the knee caused by all activities such as sitting, walking, running, jumping, cutting, etc. The goal is to disperse the forces over a greater area as opposed to isolating them.
If you look at the meniscus, you can see both the “C” shape and the wedge shape of the meniscus.
SYMPTOMS OF MENISCAL INJURIES
Meniscal injures are tears in the meniscus and are fairly common. The typical mechanism of injury is a twisting and flexing motion of the knee. There are several different types of tears that can occur, degenerative, front to back or bucket handle. These injuries must be addressed, due to the fact that if left untreated, further damage to the meniscus or the articular surface cartilage at ends of the femur or tibia can occur.
Symptoms of a meniscus tear may include but are not limited to the following:
- Pain along the either the medial (inside) or lateral (outside) joint line
- Popping or clicking in the knee
- Locking of the knee joint
EVALUATION OF MENISCAL INJURIES
Accurate diagnosis starts with the patient history, the mechanism of the injury and the physical examination. Dr. Lowe will ask a series of questions to get an idea as to how your injury occurred and what symptoms that you are having. He will then perform specific tests to try and determine the diagnosis. Many times this alone will not reveal any injury to the meniscus. An MRI may be ordered to help rule out a tear or other injury to the knee joint.
TREATMENT OF MENISCAL INJURIES
The majority of the time, tears of the meniscus need to be surgically corrected to prevent further injury of the knee joint. This is due to the fact that the meniscus has a limited blood supply. Only the outside third of the meniscus is supplied with blood. This is considered the red zone. Tears in this area can heal if repaired. Tears on the inner third of the meniscus, the white zone, is not supplied with blood and will not heal.
Surgical treatment of meniscal tears involves an arthroscopic procedure. This is where Dr. Lowe inserts a small camera and various instruments into the joint and performs the procedure through usually two small incision portals. These portals are made just below the patella and on both sides of the patellar tendon. Dependant upon the location and type of tear, Dr. Lowe will decide if he can repair the tear or if removal of the torn area has to be done. Removal of the involved area is known as a partial menisectomy. The goal is to leave as much of the healthy meniscal tissue as possible. If Dr. Lowe feels that the tear is in a location that should heal with surgical intervention, he will perform a meniscal repair using either of two methods.
An "All-Inside" meniscal repari technique uses Smith & Nephew FasT-Fix sutures implanted through the incision portals without any other incisions. An "Open Meniscal Repair" requires an additional incision and inside-to-outside Smith & Nephew Zone-Specific sutures are used. Dr. Lowe will determine during surgery which method is most appropriate to use.
EXAMPLES OF MENISCAL INJURIES
Below are some operative photos of various meniscal tears and their treatment(s).
Normal Meniscus Torn Meniscus
Torn section shaved out Meniscus repaired