What Is Medial Compartment Of The Knee

The medial compartment of the knee, a critical area for stability and function, is frequently impacted by various conditions, from osteoarthritis to meniscal tears. Understanding its anatomy, function, and potential problems is crucial for both medical professionals and individuals seeking to maintain their knee health.

Anatomy of the Medial Compartment

The medial compartment is one of three compartments within the knee joint, the other two being the lateral and patellofemoral compartments. It’s situated on the inner side of the knee and primarily involves the articulation between the medial condyle of the femur (the thigh bone) and the medial tibial plateau (the top of the shin bone). Several key structures define and support this compartment:

• Medial Femoral Condyle: This is the rounded end of the femur on the medial (inner) side of the knee. Its smooth, articular cartilage allows for low-friction movement against the tibia.
• Medial Tibial Plateau: Located at the top of the tibia, this relatively flat surface articulates with the medial femoral condyle. Like the femoral condyle, it is covered with articular cartilage.
• Medial Meniscus: A C-shaped piece of fibrocartilage situated between the medial femoral condyle and the medial tibial plateau. It acts as a shock absorber, distributing weight evenly and providing stability.
• Medial Collateral Ligament (MCL): A broad, strong ligament running along the medial side of the knee joint. It connects the femur to the tibia and is the primary stabilizer against valgus forces (forces that push the knee inward).
• Joint Capsule: The fibrous capsule that surrounds the entire knee joint, providing further stability and containing synovial fluid, which lubricates the joint.
• Muscles and Tendons: Several muscles and their tendons contribute to the function and stability of the medial compartment. These include parts of the quadriceps (specifically the vastus medialis obliquus or VMO), the hamstrings (specifically the semimembranosus and semitendinosus), and the pes anserinus tendons (sartorius, gracilis, and semitendinosus).

Function of the Medial Compartment

The medial compartment plays a vital role in the overall function of the knee. Its primary functions include:

• Weight Bearing: The medial compartment bears a significant portion of the body's weight, particularly during activities such as walking, running, and standing. The medial meniscus helps to distribute this weight evenly, preventing excessive stress on the articular cartilage.
• Stability: The MCL is crucial for providing stability against valgus forces, preventing the knee from buckling inward. The medial meniscus also contributes to stability by deepening the articulation between the femur and tibia.
• Shock Absorption: The medial meniscus acts as a shock absorber, cushioning the impact between the femur and tibia during movement. This helps to protect the articular cartilage from damage.
• Smooth Movement: The smooth articular cartilage on the femoral condyle and tibial plateau allows for low-friction movement, enabling the knee to bend, straighten, and rotate with ease.
• Proprioception: Sensory receptors within the joint capsule, ligaments, and menisci provide information to the brain about the position and movement of the knee. This proprioceptive feedback is essential for balance and coordination.

Common Problems Affecting the Medial Compartment

The medial compartment is susceptible to various injuries and conditions, which can cause pain, stiffness, and reduced function. Some of the most common problems include:

• Medial Meniscal Tears: Tears of the medial meniscus are common, particularly in athletes involved in pivoting or twisting sports. These tears can result from acute trauma or gradual degeneration. Symptoms include pain, swelling, catching or locking of the knee, and difficulty bearing weight.
• Medial Collateral Ligament (MCL) Injuries: MCL sprains or tears typically occur due to a valgus force applied to the knee, often during sports activities. The severity of the injury can range from a mild sprain (Grade I) to a complete tear (Grade III). Symptoms include pain, swelling, bruising, and instability of the knee.
• Medial Compartment Osteoarthritis: Osteoarthritis (OA) is a degenerative joint disease that affects the articular cartilage. In the medial compartment, OA can lead to cartilage breakdown, bone-on-bone contact, pain, stiffness, and reduced range of motion. This is often associated with varus deformity (bow-leggedness), which increases the load on the medial compartment.
• Bone Bruises (Contusions): These injuries involve bleeding within the bone and can occur due to direct trauma or impact. Bone bruises in the medial compartment can cause pain, swelling, and stiffness.
• Stress Fractures: Although less common, stress fractures can occur in the medial tibial plateau due to repetitive stress, especially in athletes involved in endurance activities. Symptoms include gradual onset of pain that worsens with activity.
• Chondral Defects: These are injuries to the articular cartilage, ranging from minor surface damage to full-thickness cartilage loss. Chondral defects in the medial compartment can cause pain, swelling, and catching or locking of the knee.
• Osteochondritis Dissecans (OCD): This condition involves the separation of a piece of cartilage and underlying bone from the end of the femur or tibia. OCD lesions in the medial compartment can cause pain, swelling, and locking of the knee.

Risk Factors for Medial Compartment Problems

Several factors can increase the risk of developing problems in the medial compartment of the knee:

• Age: The risk of osteoarthritis increases with age as the articular cartilage naturally wears down over time.
• Obesity: Excess weight puts increased stress on the knee joints, accelerating cartilage breakdown and increasing the risk of osteoarthritis.
• Previous Knee Injuries: Prior injuries to the knee, such as meniscal tears or ligament sprains, can increase the risk of developing osteoarthritis later in life.
• Sports Participation: Athletes involved in high-impact or pivoting sports are at higher risk for meniscal tears, ligament injuries, and cartilage damage.
• Malalignment: Varus (bow-legged) or valgus (knock-kneed) alignment of the legs can unevenly distribute weight across the knee joint, increasing the risk of osteoarthritis in the medial or lateral compartment, respectively.
• Muscle Weakness: Weakness of the muscles surrounding the knee, particularly the quadriceps and hamstrings, can contribute to instability and increase the risk of injury.
• Genetics: Some individuals may be genetically predisposed to developing osteoarthritis or other knee problems.
• Occupation: Jobs that involve repetitive kneeling, squatting, or heavy lifting can increase the risk of knee problems.

Diagnosis of Medial Compartment Problems

Diagnosing medial compartment problems typically involves a combination of:

• Medical History and Physical Examination: A doctor will ask about your symptoms, past injuries, and activity level. They will then perform a physical examination to assess the range of motion, stability, and tenderness of the knee.
• Imaging Tests:
  • X-rays: X-rays can help to identify osteoarthritis, bone fractures, and malalignment of the knee.
  • Magnetic Resonance Imaging (MRI): MRI provides detailed images of the soft tissues, including the meniscus, ligaments, and cartilage. It is useful for diagnosing meniscal tears, ligament injuries, and cartilage damage.
  • Ultrasound: Ultrasound can be used to evaluate ligaments and tendons around the knee.
  • Bone Scan: A bone scan may be used to identify stress fractures or other bone abnormalities.

Treatment Options for Medial Compartment Problems

Treatment for medial compartment problems varies depending on the specific condition, its severity, and the individual's activity level and overall health. Treatment options can be broadly categorized as:

• Non-Surgical Treatment:
  • Rest: Avoiding activities that aggravate the symptoms is often the first step in treatment.
  • Ice: Applying ice to the knee for 15-20 minutes at a time, several times a day, can help to reduce pain and swelling.
  • Compression: Using a compression bandage can help to control swelling and provide support to the knee.
  • Elevation: Elevating the leg above the heart can also help to reduce swelling.
  • Pain Medications: Over-the-counter pain relievers such as acetaminophen (Tylenol) or ibuprofen (Advil, Motrin) can help to manage pain. In some cases, a doctor may prescribe stronger pain medications.
  • Physical Therapy: Physical therapy is an important part of treatment for many medial compartment problems. A physical therapist can teach you exercises to strengthen the muscles around the knee, improve range of motion, and enhance stability.
  • Bracing: A knee brace can provide support and stability to the knee. Different types of braces are available, depending on the specific condition. For example, a hinged knee brace may be used for MCL injuries, while an unloader brace may be used for medial compartment osteoarthritis to shift weight away from the affected area.
  • Injections:
    • Corticosteroid Injections: Corticosteroid injections can provide temporary pain relief by reducing inflammation.
    • Hyaluronic Acid Injections (Viscosupplementation): Hyaluronic acid is a naturally occurring substance in the joint fluid that helps to lubricate the joint. Hyaluronic acid injections can help to improve joint lubrication and reduce pain.
    • Platelet-Rich Plasma (PRP) Injections: PRP injections involve injecting concentrated platelets from the patient's own blood into the knee. Platelets contain growth factors that can promote healing.
• Surgical Treatment: Surgical treatment may be necessary for certain medial compartment problems that do not respond to non-surgical treatment. Common surgical procedures include:
  • Arthroscopic Meniscectomy: This procedure involves removing the damaged portion of the medial meniscus. It is typically performed arthroscopically, using small incisions and a camera.
  • Meniscal Repair: If the meniscal tear is amenable to repair, the surgeon may attempt to repair the tear with sutures. Meniscal repair is generally preferred over meniscectomy, as it preserves the meniscus and helps to prevent future osteoarthritis.
  • MCL Reconstruction: In cases of severe MCL tears, the ligament may need to be reconstructed using a graft.
  • Cartilage Restoration Procedures: Various procedures can be used to treat cartilage damage in the medial compartment, including:
    • Microfracture: This procedure involves creating small fractures in the underlying bone to stimulate the growth of new cartilage.
    • Osteochondral Autograft Transplantation (OATS): This procedure involves transplanting plugs of healthy cartilage and bone from a non-weight-bearing area of the knee to the damaged area.
    • Autologous Chondrocyte Implantation (ACI): This procedure involves harvesting cartilage cells from the patient, growing them in a lab, and then implanting them back into the knee.
  • High Tibial Osteotomy (HTO): This procedure is used to correct malalignment of the leg, typically varus deformity in patients with medial compartment osteoarthritis. The surgeon cuts and realigns the tibia to shift weight away from the medial compartment.
  • Knee Replacement (Arthroplasty): In severe cases of osteoarthritis, when other treatments have failed, knee replacement surgery may be necessary. This involves replacing the damaged joint surfaces with artificial implants. Knee replacement can be either partial (unicompartmental) or total, depending on the extent of the damage.

Rehabilitation After Treatment

Rehabilitation is a crucial part of the recovery process after treatment for medial compartment problems, whether surgical or non-surgical. The goals of rehabilitation include:

• Reducing Pain and Swelling: Modalities such as ice, compression, and elevation can help to reduce pain and swelling.
• Restoring Range of Motion: Exercises to improve flexibility and range of motion are essential for restoring normal knee function.
• Strengthening Muscles: Strengthening the muscles around the knee, particularly the quadriceps, hamstrings, and calf muscles, is important for providing stability and support to the joint.
• Improving Balance and Proprioception: Exercises to improve balance and proprioception (awareness of body position) can help to prevent re-injury.
• Returning to Activities: Gradually returning to activities, as tolerated, is the ultimate goal of rehabilitation.

A physical therapist can develop an individualized rehabilitation program based on the specific condition, treatment, and the individual's goals.

Prevention of Medial Compartment Problems

While it is not always possible to prevent medial compartment problems, there are several steps that can be taken to reduce the risk:

• Maintain a Healthy Weight: Maintaining a healthy weight can reduce stress on the knee joints and lower the risk of osteoarthritis.
• Strengthen Muscles: Strengthening the muscles around the knee can provide stability and support to the joint.
• Use Proper Technique: When participating in sports or other activities, using proper technique can help to prevent injuries.
• Wear Appropriate Footwear: Wearing supportive shoes can help to align the legs and distribute weight evenly across the knee joint.
• Avoid Overuse: Avoiding overuse and allowing adequate rest can help to prevent stress fractures and other overuse injuries.
• Address Malalignment: If you have varus or valgus malalignment of the legs, talk to your doctor about treatment options, such as orthotics or surgery.

Conclusion

The medial compartment of the knee is a complex and crucial area for knee function. Understanding its anatomy, function, common problems, and treatment options is essential for maintaining knee health. Whether you are an athlete seeking to prevent injuries or an individual managing osteoarthritis, a proactive approach to knee care can help to keep you active and pain-free. If you experience persistent knee pain or other symptoms, it is important to seek medical attention for proper diagnosis and treatment.