A discoid meniscus is an abnormally shaped meniscus (cartilage that cushions the bones of the knee) present in 1% to 3% of people born in the United States. The condition is the result of abnormal formation of the meniscus during development in the womb. While some people may be unaware of their discoid meniscus and never experience symptoms related to it, they live at a higher risk of injury than those born with a normal meniscus. A discoid meniscus is commonly detected in childhood or adolescence, and often requires surgical intervention. Physical therapists provide treatment prior to and following surgery, and for conditions not requiring surgery.
What is Discoid Meniscus?
Our knees contain 2 cushions between our thigh bone (femur) and shin bone (tibia), made of cartilage called meniscus. The meniscus is normally crescent-shaped. Its role is to provide stability to the knee joint and absorb forces when we stand and move. Both menisci are attached to the shin bone (tibia) by the meniscofemoral ligament.
A discoid meniscus is present at birth. It occurs when the cartilage does not properly develop, resulting in a thicker disc- or oval-shaped meniscus. The defect most often occurs in the meniscus on the outer (lateral) part of the knee joint. Approximately 20% of individuals diagnosed with a discoid meniscus have it in both knees.
There are 3 types of discoid menisci. The classifications are:
- Incomplete Discoid Meniscus. The shape of the meniscus is a bit wider and thicker than a normal meniscus.
- Complete Discoid Meniscus. The shape of the meniscus is significantly wider than a normal meniscus, covering the shin bone (tibia).
- Wrisberg-Ligament Meniscus. The normally present meniscofemoral ligament is absent.
Their abnormal shape and thickness make discoid menisci more prone to injury and tearing. The meniscus tissue is often not capable of healing itself due to its limited blood supply, which is required for tissue healing.
Meniscal injuries most commonly occur in activities that require sudden stopping, pivoting, and "cutting," such as in sports. Pain may also be present, sometimes without a specific injury to, or a tear in, the discoid meniscus.
In some cases, arthroscopic surgery may be required to reshape the abnormal meniscus to make it as normal as possible.
How Does it Feel?
With a discoid meniscus or torn discoid meniscus, you may experience:
- Pain in your knee, most often on the outer (lateral) side of the leg.
- Sharp pain with running, jumping, cutting, or deep squatting.
- Swelling in the knee.
- Tenderness on the outer side, or less commonly on the inner side, of the knee.
- Catching or locking of the knee while walking or squatting.
- Loss of knee motion, particularly getting "stuck," while fully bending or straightening the knee.
- Loss of strength in the quadriceps (thigh) muscle.
- Discomfort with daily activities, like walking up and down stairs.
How Is It Diagnosed?
Diagnosis of a discoid meniscus begins with a thorough medical history and physical examination. Your physical therapist will assess different measures of the knee area, such as motion, strength, flexibility, tenderness, and swelling. Your physical therapist will perform several tests specific to the knee joint, and may ask you to briefly demonstrate the activities or positions that cause your pain, such as walking, squatting, and stepping up or down stairs.
If your physical therapist suspects there may be an injury inside the knee joint, such as a discoid meniscus, the therapist will likely recommend a referral to an orthopedic physician for diagnostic imaging, such as ultrasound, x-ray, or MRI. An MRI, which looks at bones, muscles, and cartilage, is the best imaging source to identify a discoid meniscus and a tear in the meniscus.
How Can a Physical Therapist Help?
When you have been diagnosed with a discoid meniscus, your physical therapist will work with you to develop a plan to help achieve your specific goals. If surgery is needed, your physical therapist will work with you after surgery. To do so, your physical therapist will select treatment strategies in any or all of the following areas:
Range of Motion. An injury or surgery to the knee joint causes the joint to be irritated, often resulting in swelling and stiffness, resulting in loss of normal motion. While it is important to regain your normal knee motion, it is also important to allow your injury to heal, without placing excessive stress on the healing joint. Your physical therapist will assess your motion, design gentle exercises to help you regain normal range of motion, and establish a plan that will balance joint protection with motion restoration.
Strength Training. Your physical therapist will teach you exercises to strengthen the muscles around the knee, so that each muscle is able to properly perform its job, and stresses are eased, so the knee joint is properly protected.
Manual Therapy.Physical therapists are trained in manual (hands-on) therapy. If needed, your physical therapist will gently move your knee cap (patella) or patellar tendon and surrounding muscles to improve their motion, flexibility, and strength. These techniques can target areas that are difficult to treat on your own.
Pain Management. Many pain-relief strategies may be implemented; the most beneficial with knee pain is to apply ice to the area, and decrease or eliminate specific activities for a certain length of time. Your physical therapist will help to identify specific movements or activities that continue to aggravate your knee joint, and will design an individual treatment plan for you, beginning with a period of rest, and gradually adding a return to certain activities as appropriate.
Functional Training.Physical therapists are experts at training athletes to function at their best. Your physical therapist will assess your movements, and teach you to adjust them to relieve any extra stress in your knee.
Education. Your physical therapist will work with you to identify and change any external factors causing your pain, such as exercise selection, footwear, or the amount of exercises you complete. Your physical therapist will develop a personal exercise program to help you return to your desired activities.
Can this Injury or Condition be Prevented?
A discoid meniscus is present at birth and, therefore, cannot be prevented. Maintaining appropriate lower-extremity mobility and muscular strength are the best methods for preventing any type of knee injury. Unfortunately, the structure of some individuals’ menisci can increase the risk of sustaining an injury. It is imperative to be aware of any knee pain that you experience, particularly with squatting, running, or cutting, as these are signs of a potential knee injury. Identifying and addressing these injuries early is helpful in their treatment.
Real Life Experiences
Ashleigh is a 15-year-old girl who has been playing soccer since she was in the first grade. She plays with her high school team during the week, and competes in tournaments with her club team on the weekends. Last weekend, while she was running and cutting in her soccer game, she felt a sharp pain in her right knee. She was able to finish playing, but after the game, she told her dad her knee was hurting. She said it had begun getting sore during one of the practices that week, but she didn’t want to tell her coach because she was worried she would not be allowed to continue to play. Now she said she felt like her knee was swollen. Her dad immediately called their local physical therapist.
Ashleigh's physical therapist performed a comprehensive health history and examination. The physical examination revealed that Ashleigh’s knee was tender, swollen, and that she had lost leg motion and strength. Because Ashleigh’s knee was so tender, her physical therapist referred her to an orthopedic surgeon. Her MRI results showed that Ashleigh had a discoid meniscus in her right knee that required surgery.
Ashleigh underwent an outpatient arthroscopic surgery, which required 2 small incision holes in the front of her knee. She was able to return home the same day. After her surgery, Ashleigh returned to physical therapy. Ashleigh used crutches for about 2 weeks after her surgery, until her leg was strong enough to walk without support. Together, Ashleigh and her physical therapist, father, and coach developed a treatment plan to help get her back on the soccer field. The treatment process began with exercises to regain motion and strength.
After about 2 months, when her knee was less tender and she had met some of the goals set in physical therapy, Ashleigh began light running, in preparation for her return to soccer. Throughout her rehabilitation, Ashleigh and her physical therapist worked together to improve the ways she moved, including her sqatting, running, and jumping form, in order to decrease the chance of her developing another knee injury. Along with her physical therapist, coach, and parents, Ashleigh developed a gradual reintegration plan for her return to soccer.
A month later, Ashleigh was back playing soccer! In order to minimize her risk of further knee problems, she continued to perform the daily exercises her physical therapist had prescribed. She also changed her routine to allow for adequate warm-up time before and after each practice. At the end of the season, thanks to Ashleigh’s goal scoring, her team won the high-school state championship!